mongoose.c

// Copyright (c) 2004-2013 Sergey Lyubka
// Copyright (c) 2013-2025 Cesanta Software Limited
// All rights reserved
//
// This software is dual-licensed: you can redistribute it and/or modify
// it under the terms of the GNU General Public License version 2 as
// published by the Free Software Foundation. For the terms of this
// license, see http://www.gnu.org/licenses/
//
// You are free to use this software under the terms of the GNU General
// Public License, but WITHOUT ANY WARRANTY; without even the implied
// warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
// See the GNU General Public License for more details.
//
// Alternatively, you can license this software under a commercial
// license, as set out in https://www.mongoose.ws/licensing/
//
// SPDX-License-Identifier: GPL-2.0-only or commercial

#include "mongoose.h"

#ifdef MG_ENABLE_LINES
#line 1 "src/base64.c"
#endif


static int mg_base64_encode_single(int c) {
  if (c < 26) {
    return c + 'A';
  } else if (c < 52) {
    return c - 26 + 'a';
  } else if (c < 62) {
    return c - 52 + '0';
  } else {
    return c == 62 ? '+' : '/';
  }
}

static int mg_base64_decode_single(int c) {
  if (c >= 'A' && c <= 'Z') {
    return c - 'A';
  } else if (c >= 'a' && c <= 'z') {
    return c + 26 - 'a';
  } else if (c >= '0' && c <= '9') {
    return c + 52 - '0';
  } else if (c == '+') {
    return 62;
  } else if (c == '/') {
    return 63;
  } else if (c == '=') {
    return 64;
  } else {
    return -1;
  }
}

size_t mg_base64_update(unsigned char ch, char *to, size_t n) {
  unsigned long rem = (n & 3) % 3;
  if (rem == 0) {
    to[n] = (char) mg_base64_encode_single(ch >> 2);
    to[++n] = (char) ((ch & 3) << 4);
  } else if (rem == 1) {
    to[n] = (char) mg_base64_encode_single(to[n] | (ch >> 4));
    to[++n] = (char) ((ch & 15) << 2);
  } else {
    to[n] = (char) mg_base64_encode_single(to[n] | (ch >> 6));
    to[++n] = (char) mg_base64_encode_single(ch & 63);
    n++;
  }
  return n;
}

size_t mg_base64_final(char *to, size_t n) {
  size_t saved = n;
  // printf("---[%.*s]\n", n, to);
  if (n & 3) n = mg_base64_update(0, to, n);
  if ((saved & 3) == 2) n--;
  // printf("    %d[%.*s]\n", n, n, to);
  while (n & 3) to[n++] = '=';
  to[n] = '\0';
  return n;
}

size_t mg_base64_encode(const unsigned char *p, size_t n, char *to, size_t dl) {
  size_t i, len = 0;
  if (dl > 0) to[0] = '\0';
  if (dl < ((n / 3) + (n % 3 ? 1 : 0)) * 4 + 1) return 0;
  for (i = 0; i < n; i++) len = mg_base64_update(p[i], to, len);
  len = mg_base64_final(to, len);
  return len;
}

size_t mg_base64_decode(const char *src, size_t n, char *dst, size_t dl) {
  const char *end = src == NULL ? NULL : src + n;  // Cannot add to NULL
  size_t len = 0;
  if (dl < n / 4 * 3 + 1) goto fail;
  while (src != NULL && src + 3 < end) {
    int a = mg_base64_decode_single(src[0]),
        b = mg_base64_decode_single(src[1]),
        c = mg_base64_decode_single(src[2]),
        d = mg_base64_decode_single(src[3]);
    if (a == 64 || a < 0 || b == 64 || b < 0 || c < 0 || d < 0) {
      goto fail;
    }
    dst[len++] = (char) ((a << 2) | (b >> 4));
    if (src[2] != '=') {
      dst[len++] = (char) ((b << 4) | (c >> 2));
      if (src[3] != '=') dst[len++] = (char) ((c << 6) | d);
    }
    src += 4;
  }
  dst[len] = '\0';
  return len;
fail:
  if (dl > 0) dst[0] = '\0';
  return 0;
}

#ifdef MG_ENABLE_LINES
#line 1 "src/dns.c"
#endif








struct dns_data {
  struct dns_data *next;
  struct mg_connection *c;
  uint64_t expire;
  uint16_t txnid;
};

static void mg_sendnsreq(struct mg_connection *, struct mg_str *, int,
                         struct mg_dns *, bool);

static void mg_dns_free(struct dns_data **head, struct dns_data *d) {
  LIST_DELETE(struct dns_data, head, d);
  free(d);
}

void mg_resolve_cancel(struct mg_connection *c) {
  struct dns_data *tmp, *d;
  struct dns_data **head = (struct dns_data **) &c->mgr->active_dns_requests;
  for (d = *head; d != NULL; d = tmp) {
    tmp = d->next;
    if (d->c == c) mg_dns_free(head, d);
  }
}

static size_t mg_dns_parse_name_depth(const uint8_t *s, size_t len, size_t ofs,
                                      char *to, size_t tolen, size_t j,
                                      int depth) {
  size_t i = 0;
  if (tolen > 0 && depth == 0) to[0] = '\0';
  if (depth > 5) return 0;
  // MG_INFO(("ofs %lx %x %x", (unsigned long) ofs, s[ofs], s[ofs + 1]));
  while (ofs + i + 1 < len) {
    size_t n = s[ofs + i];
    if (n == 0) {
      i++;
      break;
    }
    if (n & 0xc0) {
      size_t ptr = (((n & 0x3f) << 8) | s[ofs + i + 1]);  // 12 is hdr len
      // MG_INFO(("PTR %lx", (unsigned long) ptr));
      if (ptr + 1 < len && (s[ptr] & 0xc0) == 0 &&
          mg_dns_parse_name_depth(s, len, ptr, to, tolen, j, depth + 1) == 0)
        return 0;
      i += 2;
      break;
    }
    if (ofs + i + n + 1 >= len) return 0;
    if (j > 0) {
      if (j < tolen) to[j] = '.';
      j++;
    }
    if (j + n < tolen) memcpy(&to[j], &s[ofs + i + 1], n);
    j += n;
    i += n + 1;
    if (j < tolen) to[j] = '\0';  // Zero-terminate this chunk
    // MG_INFO(("--> [%s]", to));
  }
  if (tolen > 0) to[tolen - 1] = '\0';  // Make sure make sure it is nul-term
  return i;
}

static size_t mg_dns_parse_name(const uint8_t *s, size_t n, size_t ofs,
                                char *dst, size_t dstlen) {
  return mg_dns_parse_name_depth(s, n, ofs, dst, dstlen, 0, 0);
}

size_t mg_dns_parse_rr(const uint8_t *buf, size_t len, size_t ofs,
                       bool is_question, struct mg_dns_rr *rr) {
  const uint8_t *s = buf + ofs, *e = &buf[len];

  memset(rr, 0, sizeof(*rr));
  if (len < sizeof(struct mg_dns_header)) return 0;  // Too small
  if (len > 512) return 0;  //  Too large, we don't expect that
  if (s >= e) return 0;     //  Overflow

  if ((rr->nlen = (uint16_t) mg_dns_parse_name(buf, len, ofs, NULL, 0)) == 0)
    return 0;
  s += rr->nlen + 4;
  if (s > e) return 0;
  rr->atype = (uint16_t) (((uint16_t) s[-4] << 8) | s[-3]);
  rr->aclass = (uint16_t) (((uint16_t) s[-2] << 8) | s[-1]);
  if (is_question) return (size_t) (rr->nlen + 4);

  s += 6;
  if (s > e) return 0;
  rr->alen = (uint16_t) (((uint16_t) s[-2] << 8) | s[-1]);
  if (s + rr->alen > e) return 0;
  return (size_t) (rr->nlen + rr->alen + 10);
}

bool mg_dns_parse(const uint8_t *buf, size_t len, struct mg_dns_message *dm) {
  const struct mg_dns_header *h = (struct mg_dns_header *) buf;
  struct mg_dns_rr rr;
  size_t i, n, num_answers, ofs = sizeof(*h);
  memset(dm, 0, sizeof(*dm));

  if (len < sizeof(*h)) return 0;                // Too small, headers dont fit
  if (mg_ntohs(h->num_questions) > 1) return 0;  // Sanity
  num_answers = mg_ntohs(h->num_answers);
  if (num_answers > 10) {
    MG_DEBUG(("Got %u answers, ignoring beyond 10th one", num_answers));
    num_answers = 10;  // Sanity cap
  }
  dm->txnid = mg_ntohs(h->txnid);

  for (i = 0; i < mg_ntohs(h->num_questions); i++) {
    if ((n = mg_dns_parse_rr(buf, len, ofs, true, &rr)) == 0) return false;
    // MG_INFO(("Q %lu %lu %hu/%hu", ofs, n, rr.atype, rr.aclass));
    ofs += n;
  }
  for (i = 0; i < num_answers; i++) {
    if ((n = mg_dns_parse_rr(buf, len, ofs, false, &rr)) == 0) return false;
    // MG_INFO(("A -- %lu %lu %hu/%hu %s", ofs, n, rr.atype, rr.aclass,
    // dm->name));
    mg_dns_parse_name(buf, len, ofs, dm->name, sizeof(dm->name));
    ofs += n;

    if (rr.alen == 4 && rr.atype == 1 && rr.aclass == 1) {
      dm->addr.is_ip6 = false;
      memcpy(&dm->addr.ip, &buf[ofs - 4], 4);
      dm->resolved = true;
      break;  // Return success
    } else if (rr.alen == 16 && rr.atype == 28 && rr.aclass == 1) {
      dm->addr.is_ip6 = true;
      memcpy(&dm->addr.ip, &buf[ofs - 16], 16);
      dm->resolved = true;
      break;  // Return success
    }
  }
  return true;
}

static void dns_cb(struct mg_connection *c, int ev, void *ev_data) {
  struct dns_data *d, *tmp;
  struct dns_data **head = (struct dns_data **) &c->mgr->active_dns_requests;
  if (ev == MG_EV_POLL) {
    uint64_t now = *(uint64_t *) ev_data;
    for (d = *head; d != NULL; d = tmp) {
      tmp = d->next;
      // MG_DEBUG ("%lu %lu dns poll", d->expire, now));
      if (now > d->expire) mg_error(d->c, "DNS timeout");
    }
  } else if (ev == MG_EV_READ) {
    struct mg_dns_message dm;
    int resolved = 0;
    if (mg_dns_parse(c->recv.buf, c->recv.len, &dm) == false) {
      MG_ERROR(("Unexpected DNS response:"));
      mg_hexdump(c->recv.buf, c->recv.len);
    } else {
      // MG_VERBOSE(("%s %d", dm.name, dm.resolved));
      for (d = *head; d != NULL; d = tmp) {
        tmp = d->next;
        // MG_INFO(("d %p %hu %hu", d, d->txnid, dm.txnid));
        if (dm.txnid != d->txnid) continue;
        if (d->c->is_resolving) {
          if (dm.resolved) {
            dm.addr.port = d->c->rem.port;  // Save port
            d->c->rem = dm.addr;            // Copy resolved address
            MG_DEBUG(
                ("%lu %s is %M", d->c->id, dm.name, mg_print_ip, &d->c->rem));
            mg_connect_resolved(d->c);
#if MG_ENABLE_IPV6
          } else if (dm.addr.is_ip6 == false && dm.name[0] != '\0' &&
                     c->mgr->use_dns6 == false) {
            struct mg_str x = mg_str(dm.name);
            mg_sendnsreq(d->c, &x, c->mgr->dnstimeout, &c->mgr->dns6, true);
#endif
          } else {
            mg_error(d->c, "%s DNS lookup failed", dm.name);
          }
        } else {
          MG_ERROR(("%lu already resolved", d->c->id));
        }
        mg_dns_free(head, d);
        resolved = 1;
      }
    }
    if (!resolved) MG_ERROR(("stray DNS reply"));
    c->recv.len = 0;
  } else if (ev == MG_EV_CLOSE) {
    for (d = *head; d != NULL; d = tmp) {
      tmp = d->next;
      mg_error(d->c, "DNS error");
      mg_dns_free(head, d);
    }
  }
}

static bool mg_dns_send(struct mg_connection *c, const struct mg_str *name,
                        uint16_t txnid, bool ipv6) {
  struct {
    struct mg_dns_header header;
    uint8_t data[256];
  } pkt;
  size_t i, n;
  memset(&pkt, 0, sizeof(pkt));
  pkt.header.txnid = mg_htons(txnid);
  pkt.header.flags = mg_htons(0x100);
  pkt.header.num_questions = mg_htons(1);
  for (i = n = 0; i < sizeof(pkt.data) - 5; i++) {
    if (name->buf[i] == '.' || i >= name->len) {
      pkt.data[n] = (uint8_t) (i - n);
      memcpy(&pkt.data[n + 1], name->buf + n, i - n);
      n = i + 1;
    }
    if (i >= name->len) break;
  }
  memcpy(&pkt.data[n], "\x00\x00\x01\x00\x01", 5);  // A query
  n += 5;
  if (ipv6) pkt.data[n - 3] = 0x1c;  // AAAA query
  // memcpy(&pkt.data[n], "\xc0\x0c\x00\x1c\x00\x01", 6);  // AAAA query
  // n += 6;
  return mg_send(c, &pkt, sizeof(pkt.header) + n);
}

static void mg_sendnsreq(struct mg_connection *c, struct mg_str *name, int ms,
                         struct mg_dns *dnsc, bool ipv6) {
  struct dns_data *d = NULL;
  if (dnsc->url == NULL) {
    mg_error(c, "DNS server URL is NULL. Call mg_mgr_init()");
  } else if (dnsc->c == NULL) {
    dnsc->c = mg_connect(c->mgr, dnsc->url, NULL, NULL);
    if (dnsc->c != NULL) {
      dnsc->c->pfn = dns_cb;
      // dnsc->c->is_hexdumping = 1;
    }
  }
  if (dnsc->c == NULL) {
    mg_error(c, "resolver");
  } else if ((d = (struct dns_data *) calloc(1, sizeof(*d))) == NULL) {
    mg_error(c, "resolve OOM");
  } else {
    struct dns_data *reqs = (struct dns_data *) c->mgr->active_dns_requests;
    d->txnid = reqs ? (uint16_t) (reqs->txnid + 1) : 1;
    d->next = (struct dns_data *) c->mgr->active_dns_requests;
    c->mgr->active_dns_requests = d;
    d->expire = mg_millis() + (uint64_t) ms;
    d->c = c;
    c->is_resolving = 1;
    MG_VERBOSE(("%lu resolving %.*s @ %s, txnid %hu", c->id, (int) name->len,
                name->buf, dnsc->url, d->txnid));
    if (!mg_dns_send(dnsc->c, name, d->txnid, ipv6)) {
      mg_error(dnsc->c, "DNS send");
    }
  }
}

void mg_resolve(struct mg_connection *c, const char *url) {
  struct mg_str host = mg_url_host(url);
  c->rem.port = mg_htons(mg_url_port(url));
  if (mg_aton(host, &c->rem)) {
    // host is an IP address, do not fire name resolution
    mg_connect_resolved(c);
  } else {
    // host is not an IP, send DNS resolution request
    struct mg_dns *dns = c->mgr->use_dns6 ? &c->mgr->dns6 : &c->mgr->dns4;
    mg_sendnsreq(c, &host, c->mgr->dnstimeout, dns, c->mgr->use_dns6);
  }
}

#ifdef MG_ENABLE_LINES
#line 1 "src/event.c"
#endif






void mg_call(struct mg_connection *c, int ev, void *ev_data) {
#if MG_ENABLE_PROFILE
  const char *names[] = {
      "EV_ERROR",    "EV_OPEN",      "EV_POLL",      "EV_RESOLVE",
      "EV_CONNECT",  "EV_ACCEPT",    "EV_TLS_HS",    "EV_READ",
      "EV_WRITE",    "EV_CLOSE",     "EV_HTTP_MSG",  "EV_HTTP_CHUNK",
      "EV_WS_OPEN",  "EV_WS_MSG",    "EV_WS_CTL",    "EV_MQTT_CMD",
      "EV_MQTT_MSG", "EV_MQTT_OPEN", "EV_SNTP_TIME", "EV_USER"};
  if (ev != MG_EV_POLL && ev < (int) (sizeof(names) / sizeof(names[0]))) {
    MG_PROF_ADD(c, names[ev]);
  }
#endif
  // Fire protocol handler first, user handler second. See #2559
  if (c->pfn != NULL) c->pfn(c, ev, ev_data);
  if (c->fn != NULL) c->fn(c, ev, ev_data);
}

void mg_error(struct mg_connection *c, const char *fmt, ...) {
  char buf[64];
  va_list ap;
  va_start(ap, fmt);
  mg_vsnprintf(buf, sizeof(buf), fmt, &ap);
  va_end(ap);
  MG_ERROR(("%lu %ld %s", c->id, c->fd, buf));
  c->is_closing = 1;             // Set is_closing before sending MG_EV_CALL
  mg_call(c, MG_EV_ERROR, buf);  // Let user handler override it
}

#ifdef MG_ENABLE_LINES
#line 1 "src/flash.c"
#endif





#if MG_OTA != MG_OTA_NONE && MG_OTA != MG_OTA_CUSTOM

static char *s_addr;      // Current address to write to
static size_t s_size;     // Firmware size to flash. In-progress indicator
static uint32_t s_crc32;  // Firmware checksum

bool mg_ota_flash_begin(size_t new_firmware_size, struct mg_flash *flash) {
  bool ok = false;
  if (s_size) {
    MG_ERROR(("OTA already in progress. Call mg_ota_end()"));
  } else {
    size_t half = flash->size / 2;
    s_crc32 = 0;
    s_addr = (char *) flash->start + half;
    MG_DEBUG(("FW %lu bytes, max %lu", new_firmware_size, half));
    if (new_firmware_size < half) {
      ok = true;
      s_size = new_firmware_size;
      MG_INFO(("Starting OTA, firmware size %lu", s_size));
    } else {
      MG_ERROR(("Firmware %lu is too big to fit %lu", new_firmware_size, half));
    }
  }
  return ok;
}

bool mg_ota_flash_write(const void *buf, size_t len, struct mg_flash *flash) {
  bool ok = false;
  if (s_size == 0) {
    MG_ERROR(("OTA is not started, call mg_ota_begin()"));
  } else {
    size_t len_aligned_down = MG_ROUND_DOWN(len, flash->align);
    if (len_aligned_down) ok = flash->write_fn(s_addr, buf, len_aligned_down);
    if (len_aligned_down < len) {
      size_t left = len - len_aligned_down;
      char tmp[flash->align];
      memset(tmp, 0xff, sizeof(tmp));
      memcpy(tmp, (char *) buf + len_aligned_down, left);
      ok = flash->write_fn(s_addr + len_aligned_down, tmp, sizeof(tmp));
    }
    s_crc32 = mg_crc32(s_crc32, (char *) buf, len);  // Update CRC
    MG_DEBUG(("%#x %p %lu -> %d", s_addr - len, buf, len, ok));
    s_addr += len;
  }
  return ok;
}

bool mg_ota_flash_end(struct mg_flash *flash) {
  char *base = (char *) flash->start + flash->size / 2;
  bool ok = false;
  if (s_size) {
    size_t size = (size_t) (s_addr - base);
    uint32_t crc32 = mg_crc32(0, base, s_size);
    if (size == s_size && crc32 == s_crc32) ok = true;
    MG_DEBUG(("CRC: %x/%x, size: %lu/%lu, status: %s", s_crc32, crc32, s_size,
              size, ok ? "ok" : "fail"));
    s_size = 0;
    if (ok) ok = flash->swap_fn();
  }
  MG_INFO(("Finishing OTA: %s", ok ? "ok" : "fail"));
  return ok;
}

#endif

#ifdef MG_ENABLE_LINES
#line 1 "src/fmt.c"
#endif




static bool is_digit(int c) {
  return c >= '0' && c <= '9';
}

static int addexp(char *buf, int e, int sign) {
  int n = 0;
  buf[n++] = 'e';
  buf[n++] = (char) sign;
  if (e > 400) return 0;
  if (e < 10) buf[n++] = '0';
  if (e >= 100) buf[n++] = (char) (e / 100 + '0'), e -= 100 * (e / 100);
  if (e >= 10) buf[n++] = (char) (e / 10 + '0'), e -= 10 * (e / 10);
  buf[n++] = (char) (e + '0');
  return n;
}

static int xisinf(double x) {
  union {
    double f;
    uint64_t u;
  } ieee754 = {x};
  return ((unsigned) (ieee754.u >> 32) & 0x7fffffff) == 0x7ff00000 &&
         ((unsigned) ieee754.u == 0);
}

static int xisnan(double x) {
  union {
    double f;
    uint64_t u;
  } ieee754 = {x};
  return ((unsigned) (ieee754.u >> 32) & 0x7fffffff) +
             ((unsigned) ieee754.u != 0) >
         0x7ff00000;
}

static size_t mg_dtoa(char *dst, size_t dstlen, double d, int width, bool tz) {
  char buf[40];
  int i, s = 0, n = 0, e = 0;
  double t, mul, saved;
  if (d == 0.0) return mg_snprintf(dst, dstlen, "%s", "0");
  if (xisinf(d)) return mg_snprintf(dst, dstlen, "%s", d > 0 ? "inf" : "-inf");
  if (xisnan(d)) return mg_snprintf(dst, dstlen, "%s", "nan");
  if (d < 0.0) d = -d, buf[s++] = '-';

  // Round
  saved = d;
  if (tz) {
    mul = 1.0;
    while (d >= 10.0 && d / mul >= 10.0) mul *= 10.0;
  } else {
    mul = 0.1;
  }

  while (d <= 1.0 && d / mul <= 1.0) mul /= 10.0;
  for (i = 0, t = mul * 5; i < width; i++) t /= 10.0;

  d += t;

  // Calculate exponent, and 'mul' for scientific representation
  mul = 1.0;
  while (d >= 10.0 && d / mul >= 10.0) mul *= 10.0, e++;
  while (d < 1.0 && d / mul < 1.0) mul /= 10.0, e--;
  // printf(" --> %g %d %g %g\n", saved, e, t, mul);

  if (tz && e >= width && width > 1) {
    n = (int) mg_dtoa(buf, sizeof(buf), saved / mul, width, tz);
    // printf(" --> %.*g %d [%.*s]\n", 10, d / t, e, n, buf);
    n += addexp(buf + s + n, e, '+');
    return mg_snprintf(dst, dstlen, "%.*s", n, buf);
  } else if (tz && e <= -width && width > 1) {
    n = (int) mg_dtoa(buf, sizeof(buf), saved / mul, width, tz);
    // printf(" --> %.*g %d [%.*s]\n", 10, d / mul, e, n, buf);
    n += addexp(buf + s + n, -e, '-');
    return mg_snprintf(dst, dstlen, "%.*s", n, buf);
  } else {
    int targ_width = width;
    for (i = 0, t = mul; t >= 1.0 && s + n < (int) sizeof(buf); i++) {
      int ch = (int) (d / t);
      if (n > 0 || ch > 0) buf[s + n++] = (char) (ch + '0');
      d -= ch * t;
      t /= 10.0;
    }
    // printf(" --> [%g] -> %g %g (%d) [%.*s]\n", saved, d, t, n, s + n, buf);
    if (n == 0) buf[s++] = '0';
    while (t >= 1.0 && n + s < (int) sizeof(buf)) buf[n++] = '0', t /= 10.0;
    if (s + n < (int) sizeof(buf)) buf[n + s++] = '.';
    // printf(" 1--> [%g] -> [%.*s]\n", saved, s + n, buf);
    if (!tz && n > 0) targ_width = width + n;
    for (i = 0, t = 0.1; s + n < (int) sizeof(buf) && n < targ_width; i++) {
      int ch = (int) (d / t);
      buf[s + n++] = (char) (ch + '0');
      d -= ch * t;
      t /= 10.0;
    }
  }

  while (tz && n > 0 && buf[s + n - 1] == '0') n--;  // Trim trailing zeroes
  if (tz && n > 0 && buf[s + n - 1] == '.') n--;           // Trim trailing dot
  n += s;
  if (n >= (int) sizeof(buf)) n = (int) sizeof(buf) - 1;
  buf[n] = '\0';
  return mg_snprintf(dst, dstlen, "%s", buf);
}

static size_t mg_lld(char *buf, int64_t val, bool is_signed, bool is_hex) {
  const char *letters = "0123456789abcdef";
  uint64_t v = (uint64_t) val;
  size_t s = 0, n, i;
  if (is_signed && val < 0) buf[s++] = '-', v = (uint64_t) (-val);
  // This loop prints a number in reverse order. I guess this is because we
  // write numbers from right to left: least significant digit comes last.
  // Maybe because we use Arabic numbers, and Arabs write RTL?
  if (is_hex) {
    for (n = 0; v; v >>= 4) buf[s + n++] = letters[v & 15];
  } else {
    for (n = 0; v; v /= 10) buf[s + n++] = letters[v % 10];
  }
  // Reverse a string
  for (i = 0; i < n / 2; i++) {
    char t = buf[s + i];
    buf[s + i] = buf[s + n - i - 1], buf[s + n - i - 1] = t;
  }
  if (val == 0) buf[n++] = '0';  // Handle special case
  return n + s;
}

static size_t scpy(void (*out)(char, void *), void *ptr, char *buf,
                          size_t len) {
  size_t i = 0;
  while (i < len && buf[i] != '\0') out(buf[i++], ptr);
  return i;
}

size_t mg_xprintf(void (*out)(char, void *), void *ptr, const char *fmt, ...) {
  size_t len = 0;
  va_list ap;
  va_start(ap, fmt);
  len = mg_vxprintf(out, ptr, fmt, &ap);
  va_end(ap);
  return len;
}

size_t mg_vxprintf(void (*out)(char, void *), void *param, const char *fmt,
                   va_list *ap) {
  size_t i = 0, n = 0;
  while (fmt[i] != '\0') {
    if (fmt[i] == '%') {
      size_t j, k, x = 0, is_long = 0, w = 0 /* width */, pr = ~0U /* prec */;
      char pad = ' ', minus = 0, c = fmt[++i];
      if (c == '#') x++, c = fmt[++i];
      if (c == '-') minus++, c = fmt[++i];
      if (c == '0') pad = '0', c = fmt[++i];
      while (is_digit(c)) w *= 10, w += (size_t) (c - '0'), c = fmt[++i];
      if (c == '.') {
        c = fmt[++i];
        if (c == '*') {
          pr = (size_t) va_arg(*ap, int);
          c = fmt[++i];
        } else {
          pr = 0;
          while (is_digit(c)) pr *= 10, pr += (size_t) (c - '0'), c = fmt[++i];
        }
      }
      while (c == 'h') c = fmt[++i];  // Treat h and hh as int
      if (c == 'l') {
        is_long++, c = fmt[++i];
        if (c == 'l') is_long++, c = fmt[++i];
      }
      if (c == 'p') x = 1, is_long = 1;
      if (c == 'd' || c == 'u' || c == 'x' || c == 'X' || c == 'p' ||
          c == 'g' || c == 'f') {
        bool s = (c == 'd'), h = (c == 'x' || c == 'X' || c == 'p');
        char tmp[40];
        size_t xl = x ? 2 : 0;
        if (c == 'g' || c == 'f') {
          double v = va_arg(*ap, double);
          if (pr == ~0U) pr = 6;
          k = mg_dtoa(tmp, sizeof(tmp), v, (int) pr, c == 'g');
        } else if (is_long == 2) {
          int64_t v = va_arg(*ap, int64_t);
          k = mg_lld(tmp, v, s, h);
        } else if (is_long == 1) {
          long v = va_arg(*ap, long);
          k = mg_lld(tmp, s ? (int64_t) v : (int64_t) (unsigned long) v, s, h);
        } else {
          int v = va_arg(*ap, int);
          k = mg_lld(tmp, s ? (int64_t) v : (int64_t) (unsigned) v, s, h);
        }
        for (j = 0; j < xl && w > 0; j++) w--;
        for (j = 0; pad == ' ' && !minus && k < w && j + k < w; j++)
          n += scpy(out, param, &pad, 1);
        n += scpy(out, param, (char *) "0x", xl);
        for (j = 0; pad == '0' && k < w && j + k < w; j++)
          n += scpy(out, param, &pad, 1);
        n += scpy(out, param, tmp, k);
        for (j = 0; pad == ' ' && minus && k < w && j + k < w; j++)
          n += scpy(out, param, &pad, 1);
      } else if (c == 'm' || c == 'M') {
        mg_pm_t f = va_arg(*ap, mg_pm_t);
        if (c == 'm') out('"', param);
        n += f(out, param, ap);
        if (c == 'm') n += 2, out('"', param);
      } else if (c == 'c') {
        int ch = va_arg(*ap, int);
        out((char) ch, param);
        n++;
      } else if (c == 's') {
        char *p = va_arg(*ap, char *);
        if (pr == ~0U) pr = p == NULL ? 0 : strlen(p);
        for (j = 0; !minus && pr < w && j + pr < w; j++)
          n += scpy(out, param, &pad, 1);
        n += scpy(out, param, p, pr);
        for (j = 0; minus && pr < w && j + pr < w; j++)
          n += scpy(out, param, &pad, 1);
      } else if (c == '%') {
        out('%', param);
        n++;
      } else {
        out('%', param);
        out(c, param);
        n += 2;
      }
      i++;
    } else {
      out(fmt[i], param), n++, i++;
    }
  }
  return n;
}

#ifdef MG_ENABLE_LINES
#line 1 "src/fs.c"
#endif




struct mg_fd *mg_fs_open(struct mg_fs *fs, const char *path, int flags) {
  struct mg_fd *fd = (struct mg_fd *) calloc(1, sizeof(*fd));
  if (fd != NULL) {
    fd->fd = fs->op(path, flags);
    fd->fs = fs;
    if (fd->fd == NULL) {
      free(fd);
      fd = NULL;
    }
  }
  return fd;
}

void mg_fs_close(struct mg_fd *fd) {
  if (fd != NULL) {
    fd->fs->cl(fd->fd);
    free(fd);
  }
}

struct mg_str mg_file_read(struct mg_fs *fs, const char *path) {
  struct mg_str result = {NULL, 0};
  void *fp;
  fs->st(path, &result.len, NULL);
  if ((fp = fs->op(path, MG_FS_READ)) != NULL) {
    result.buf = (char *) calloc(1, result.len + 1);
    if (result.buf != NULL &&
        fs->rd(fp, (void *) result.buf, result.len) != result.len) {
      free((void *) result.buf);
      result.buf = NULL;
    }
    fs->cl(fp);
  }
  if (result.buf == NULL) result.len = 0;
  return result;
}

bool mg_file_write(struct mg_fs *fs, const char *path, const void *buf,
                   size_t len) {
  bool result = false;
  struct mg_fd *fd;
  char tmp[MG_PATH_MAX];
  mg_snprintf(tmp, sizeof(tmp), "%s..%d", path, rand());
  if ((fd = mg_fs_open(fs, tmp, MG_FS_WRITE)) != NULL) {
    result = fs->wr(fd->fd, buf, len) == len;
    mg_fs_close(fd);
    if (result) {
      fs->rm(path);
      fs->mv(tmp, path);
    } else {
      fs->rm(tmp);
    }
  }
  return result;
}

bool mg_file_printf(struct mg_fs *fs, const char *path, const char *fmt, ...) {
  va_list ap;
  char *data;
  bool result = false;
  va_start(ap, fmt);
  data = mg_vmprintf(fmt, &ap);
  va_end(ap);
  result = mg_file_write(fs, path, data, strlen(data));
  free(data);
  return result;
}

// This helper function allows to scan a filesystem in a sequential way,
// without using callback function:
//      char buf[100] = "";
//      while (mg_fs_ls(&mg_fs_posix, "./", buf, sizeof(buf))) {
//        ...
static void mg_fs_ls_fn(const char *filename, void *param) {
  struct mg_str *s = (struct mg_str *) param;
  if (s->buf[0] == '\0') {
    mg_snprintf((char *) s->buf, s->len, "%s", filename);
  } else if (strcmp(s->buf, filename) == 0) {
    ((char *) s->buf)[0] = '\0';  // Fetch next file
  }
}

bool mg_fs_ls(struct mg_fs *fs, const char *path, char *buf, size_t len) {
  struct mg_str s = {buf, len};
  fs->ls(path, mg_fs_ls_fn, &s);
  return buf[0] != '\0';
}

#ifdef MG_ENABLE_LINES
#line 1 "src/fs_fat.c"
#endif



#if MG_ENABLE_FATFS
#include <ff.h>

static int mg_days_from_epoch(int y, int m, int d) {
  y -= m <= 2;
  int era = y / 400;
  int yoe = y - era * 400;
  int doy = (153 * (m + (m > 2 ? -3 : 9)) + 2) / 5 + d - 1;
  int doe = yoe * 365 + yoe / 4 - yoe / 100 + doy;
  return era * 146097 + doe - 719468;
}

static time_t mg_timegm(const struct tm *t) {
  int year = t->tm_year + 1900;
  int month = t->tm_mon;  // 0-11
  if (month > 11) {
    year += month / 12;
    month %= 12;
  } else if (month < 0) {
    int years_diff = (11 - month) / 12;
    year -= years_diff;
    month += 12 * years_diff;
  }
  int x = mg_days_from_epoch(year, month + 1, t->tm_mday);
  return 60 * (60 * (24L * x + t->tm_hour) + t->tm_min) + t->tm_sec;
}

static time_t ff_time_to_epoch(uint16_t fdate, uint16_t ftime) {
  struct tm tm;
  memset(&tm, 0, sizeof(struct tm));
  tm.tm_sec = (ftime << 1) & 0x3e;
  tm.tm_min = ((ftime >> 5) & 0x3f);
  tm.tm_hour = ((ftime >> 11) & 0x1f);
  tm.tm_mday = (fdate & 0x1f);
  tm.tm_mon = ((fdate >> 5) & 0x0f) - 1;
  tm.tm_year = ((fdate >> 9) & 0x7f) + 80;
  return mg_timegm(&tm);
}

static int ff_stat(const char *path, size_t *size, time_t *mtime) {
  FILINFO fi;
  if (path[0] == '\0') {
    if (size) *size = 0;
    if (mtime) *mtime = 0;
    return MG_FS_DIR;
  } else if (f_stat(path, &fi) == 0) {
    if (size) *size = (size_t) fi.fsize;
    if (mtime) *mtime = ff_time_to_epoch(fi.fdate, fi.ftime);
    return MG_FS_READ | MG_FS_WRITE | ((fi.fattrib & AM_DIR) ? MG_FS_DIR : 0);
  } else {
    return 0;
  }
}

static void ff_list(const char *dir, void (*fn)(const char *, void *),
                    void *userdata) {
  DIR d;
  FILINFO fi;
  if (f_opendir(&d, dir) == FR_OK) {
    while (f_readdir(&d, &fi) == FR_OK && fi.fname[0] != '\0') {
      if (!strcmp(fi.fname, ".") || !strcmp(fi.fname, "..")) continue;
      fn(fi.fname, userdata);
    }
    f_closedir(&d);
  }
}

static void *ff_open(const char *path, int flags) {
  FIL f;
  unsigned char mode = FA_READ;
  if (flags & MG_FS_WRITE) mode |= FA_WRITE | FA_OPEN_ALWAYS | FA_OPEN_APPEND;
  if (f_open(&f, path, mode) == 0) {
    FIL *fp;
    if ((fp = calloc(1, sizeof(*fp))) != NULL) {
      memcpy(fp, &f, sizeof(*fp));
      return fp;
    }
  }
  return NULL;
}

static void ff_close(void *fp) {
  if (fp != NULL) {
    f_close((FIL *) fp);
    free(fp);
  }
}

static size_t ff_read(void *fp, void *buf, size_t len) {
  UINT n = 0, misalign = ((size_t) buf) & 3;
  if (misalign) {
    char aligned[4];
    f_read((FIL *) fp, aligned, len > misalign ? misalign : len, &n);
    memcpy(buf, aligned, n);
  } else {
    f_read((FIL *) fp, buf, len, &n);
  }
  return n;
}

static size_t ff_write(void *fp, const void *buf, size_t len) {
  UINT n = 0;
  return f_write((FIL *) fp, (char *) buf, len, &n) == FR_OK ? n : 0;
}

static size_t ff_seek(void *fp, size_t offset) {
  f_lseek((FIL *) fp, offset);
  return offset;
}

static bool ff_rename(const char *from, const char *to) {
  return f_rename(from, to) == FR_OK;
}

static bool ff_remove(const char *path) {
  return f_unlink(path) == FR_OK;
}

static bool ff_mkdir(const char *path) {
  return f_mkdir(path) == FR_OK;
}

struct mg_fs mg_fs_fat = {ff_stat,  ff_list, ff_open,   ff_close,  ff_read,
                          ff_write, ff_seek, ff_rename, ff_remove, ff_mkdir};
#endif

#ifdef MG_ENABLE_LINES
#line 1 "src/fs_packed.c"
#endif




struct packed_file {
  const char *data;
  size_t size;
  size_t pos;
};

#if MG_ENABLE_PACKED_FS
#else
const char *mg_unpack(const char *path, size_t *size, time_t *mtime) {
  if (size != NULL) *size = 0;
  if (mtime != NULL) *mtime = 0;
  (void) path;
  return NULL;
}
const char *mg_unlist(size_t no) {
  (void) no;
  return NULL;
}
#endif

struct mg_str mg_unpacked(const char *path) {
  size_t len = 0;
  const char *buf = mg_unpack(path, &len, NULL);
  return mg_str_n(buf, len);
}

static int is_dir_prefix(const char *prefix, size_t n, const char *path) {
  // MG_INFO(("[%.*s] [%s] %c", (int) n, prefix, path, path[n]));
  return n < strlen(path) && strncmp(prefix, path, n) == 0 &&
         (n == 0 || path[n] == '/' || path[n - 1] == '/');
}

static int packed_stat(const char *path, size_t *size, time_t *mtime) {
  const char *p;
  size_t i, n = strlen(path);
  if (mg_unpack(path, size, mtime)) return MG_FS_READ;  // Regular file
  // Scan all files. If `path` is a dir prefix for any of them, it's a dir
  for (i = 0; (p = mg_unlist(i)) != NULL; i++) {
    if (is_dir_prefix(path, n, p)) return MG_FS_DIR;
  }
  return 0;
}

static void packed_list(const char *dir, void (*fn)(const char *, void *),
                        void *userdata) {
  char buf[MG_PATH_MAX], tmp[sizeof(buf)];
  const char *path, *begin, *end;
  size_t i, n = strlen(dir);
  tmp[0] = '\0';  // Previously listed entry
  for (i = 0; (path = mg_unlist(i)) != NULL; i++) {
    if (!is_dir_prefix(dir, n, path)) continue;
    begin = &path[n + 1];
    end = strchr(begin, '/');
    if (end == NULL) end = begin + strlen(begin);
    mg_snprintf(buf, sizeof(buf), "%.*s", (int) (end - begin), begin);
    buf[sizeof(buf) - 1] = '\0';
    // If this entry has been already listed, skip
    // NOTE: we're assuming that file list is sorted alphabetically
    if (strcmp(buf, tmp) == 0) continue;
    fn(buf, userdata);  // Not yet listed, call user function
    strcpy(tmp, buf);   // And save this entry as listed
  }
}

static void *packed_open(const char *path, int flags) {
  size_t size = 0;
  const char *data = mg_unpack(path, &size, NULL);
  struct packed_file *fp = NULL;
  if (data == NULL) return NULL;
  if (flags & MG_FS_WRITE) return NULL;
  if ((fp = (struct packed_file *) calloc(1, sizeof(*fp))) != NULL) {
    fp->size = size;
    fp->data = data;
  }
  return (void *) fp;
}

static void packed_close(void *fp) {
  if (fp != NULL) free(fp);
}

static size_t packed_read(void *fd, void *buf, size_t len) {
  struct packed_file *fp = (struct packed_file *) fd;
  if (fp->pos + len > fp->size) len = fp->size - fp->pos;
  memcpy(buf, &fp->data[fp->pos], len);
  fp->pos += len;
  return len;
}

static size_t packed_write(void *fd, const void *buf, size_t len) {
  (void) fd, (void) buf, (void) len;
  return 0;
}

static size_t packed_seek(void *fd, size_t offset) {
  struct packed_file *fp = (struct packed_file *) fd;
  fp->pos = offset;
  if (fp->pos > fp->size) fp->pos = fp->size;
  return fp->pos;
}

static bool packed_rename(const char *from, const char *to) {
  (void) from, (void) to;
  return false;
}

static bool packed_remove(const char *path) {
  (void) path;
  return false;
}

static bool packed_mkdir(const char *path) {
  (void) path;
  return false;
}

struct mg_fs mg_fs_packed = {
    packed_stat,  packed_list, packed_open,   packed_close,  packed_read,
    packed_write, packed_seek, packed_rename, packed_remove, packed_mkdir};

#ifdef MG_ENABLE_LINES
#line 1 "src/fs_posix.c"
#endif


#if MG_ENABLE_POSIX_FS

#ifndef MG_STAT_STRUCT
#define MG_STAT_STRUCT stat
#endif

#ifndef MG_STAT_FUNC
#define MG_STAT_FUNC stat
#endif

static int p_stat(const char *path, size_t *size, time_t *mtime) {
#if !defined(S_ISDIR)
  MG_ERROR(("stat() API is not supported. %p %p %p", path, size, mtime));
  return 0;
#else
#if MG_ARCH == MG_ARCH_WIN32
  struct _stati64 st;
  wchar_t tmp[MG_PATH_MAX];
  MultiByteToWideChar(CP_UTF8, 0, path, -1, tmp, sizeof(tmp) / sizeof(tmp[0]));
  if (_wstati64(tmp, &st) != 0) return 0;
  // If path is a symlink, windows reports 0 in st.st_size.
  // Get a real file size by opening it and jumping to the end
  if (st.st_size == 0 && (st.st_mode & _S_IFREG)) {
    FILE *fp = _wfopen(tmp, L"rb");
    if (fp != NULL) {
      fseek(fp, 0, SEEK_END);
      if (ftell(fp) > 0) st.st_size = ftell(fp);  // Use _ftelli64 on win10+
      fclose(fp);
    }
  }
#else
  struct MG_STAT_STRUCT st;
  if (MG_STAT_FUNC(path, &st) != 0) return 0;
#endif
  if (size) *size = (size_t) st.st_size;
  if (mtime) *mtime = st.st_mtime;
  return MG_FS_READ | MG_FS_WRITE | (S_ISDIR(st.st_mode) ? MG_FS_DIR : 0);
#endif
}

#if MG_ARCH == MG_ARCH_WIN32
struct dirent {
  char d_name[MAX_PATH];
};

typedef struct win32_dir {
  HANDLE handle;
  WIN32_FIND_DATAW info;
  struct dirent result;
} DIR;

#if 0
int gettimeofday(struct timeval *tv, void *tz) {
  FILETIME ft;
  unsigned __int64 tmpres = 0;

  if (tv != NULL) {
    GetSystemTimeAsFileTime(&ft);
    tmpres |= ft.dwHighDateTime;
    tmpres <<= 32;
    tmpres |= ft.dwLowDateTime;
    tmpres /= 10;  // convert into microseconds
    tmpres -= (int64_t) 11644473600000000;
    tv->tv_sec = (long) (tmpres / 1000000UL);
    tv->tv_usec = (long) (tmpres % 1000000UL);
  }
  (void) tz;
  return 0;
}
#endif

static int to_wchar(const char *path, wchar_t *wbuf, size_t wbuf_len) {
  int ret;
  char buf[MAX_PATH * 2], buf2[MAX_PATH * 2], *p;
  strncpy(buf, path, sizeof(buf));
  buf[sizeof(buf) - 1] = '\0';
  // Trim trailing slashes. Leave backslash for paths like "X:\"
  p = buf + strlen(buf) - 1;
  while (p > buf && p[-1] != ':' && (p[0] == '\\' || p[0] == '/')) *p-- = '\0';
  memset(wbuf, 0, wbuf_len * sizeof(wchar_t));
  ret = MultiByteToWideChar(CP_UTF8, 0, buf, -1, wbuf, (int) wbuf_len);
  // Convert back to Unicode. If doubly-converted string does not match the
  // original, something is fishy, reject.
  WideCharToMultiByte(CP_UTF8, 0, wbuf, (int) wbuf_len, buf2, sizeof(buf2),
                      NULL, NULL);
  if (strcmp(buf, buf2) != 0) {
    wbuf[0] = L'\0';
    ret = 0;
  }
  return ret;
}

DIR *opendir(const char *name) {
  DIR *d = NULL;
  wchar_t wpath[MAX_PATH];
  DWORD attrs;

  if (name == NULL) {
    SetLastError(ERROR_BAD_ARGUMENTS);
  } else if ((d = (DIR *) calloc(1, sizeof(*d))) == NULL) {
    SetLastError(ERROR_NOT_ENOUGH_MEMORY);
  } else {
    to_wchar(name, wpath, sizeof(wpath) / sizeof(wpath[0]));
    attrs = GetFileAttributesW(wpath);
    if (attrs != 0Xffffffff && (attrs & FILE_ATTRIBUTE_DIRECTORY)) {
      (void) wcscat(wpath, L"\\*");
      d->handle = FindFirstFileW(wpath, &d->info);
      d->result.d_name[0] = '\0';
    } else {
      free(d);
      d = NULL;
    }
  }
  return d;
}

int closedir(DIR *d) {
  int result = 0;
  if (d != NULL) {
    if (d->handle != INVALID_HANDLE_VALUE)
      result = FindClose(d->handle) ? 0 : -1;
    free(d);
  } else {
    result = -1;
    SetLastError(ERROR_BAD_ARGUMENTS);
  }
  return result;
}

struct dirent *readdir(DIR *d) {
  struct dirent *result = NULL;
  if (d != NULL) {
    memset(&d->result, 0, sizeof(d->result));
    if (d->handle != INVALID_HANDLE_VALUE) {
      result = &d->result;
      WideCharToMultiByte(CP_UTF8, 0, d->info.cFileName, -1, result->d_name,
                          sizeof(result->d_name), NULL, NULL);
      if (!FindNextFileW(d->handle, &d->info)) {
        FindClose(d->handle);
        d->handle = INVALID_HANDLE_VALUE;
      }
    } else {
      SetLastError(ERROR_FILE_NOT_FOUND);
    }
  } else {
    SetLastError(ERROR_BAD_ARGUMENTS);
  }
  return result;
}
#endif

static void p_list(const char *dir, void (*fn)(const char *, void *),
                   void *userdata) {
#if MG_ENABLE_DIRLIST
  struct dirent *dp;
  DIR *dirp;
  if ((dirp = (opendir(dir))) == NULL) return;
  while ((dp = readdir(dirp)) != NULL) {
    if (!strcmp(dp->d_name, ".") || !strcmp(dp->d_name, "..")) continue;
    fn(dp->d_name, userdata);
  }
  closedir(dirp);
#else
  (void) dir, (void) fn, (void) userdata;
#endif
}

static void *p_open(const char *path, int flags) {
#if MG_ARCH == MG_ARCH_WIN32
  const char *mode = flags == MG_FS_READ ? "rb" : "a+b";
  wchar_t b1[MG_PATH_MAX], b2[10];
  MultiByteToWideChar(CP_UTF8, 0, path, -1, b1, sizeof(b1) / sizeof(b1[0]));
  MultiByteToWideChar(CP_UTF8, 0, mode, -1, b2, sizeof(b2) / sizeof(b2[0]));
  return (void *) _wfopen(b1, b2);
#else
  const char *mode = flags == MG_FS_READ ? "rbe" : "a+be";  // e for CLOEXEC
  return (void *) fopen(path, mode);
#endif
}

static void p_close(void *fp) {
  fclose((FILE *) fp);
}

static size_t p_read(void *fp, void *buf, size_t len) {
  return fread(buf, 1, len, (FILE *) fp);
}

static size_t p_write(void *fp, const void *buf, size_t len) {
  return fwrite(buf, 1, len, (FILE *) fp);
}

static size_t p_seek(void *fp, size_t offset) {
#if (defined(_FILE_OFFSET_BITS) && _FILE_OFFSET_BITS == 64) ||  \
    (defined(_POSIX_C_SOURCE) && _POSIX_C_SOURCE >= 200112L) || \
    (defined(_XOPEN_SOURCE) && _XOPEN_SOURCE >= 600)
  if (fseeko((FILE *) fp, (off_t) offset, SEEK_SET) != 0) (void) 0;
#else
  if (fseek((FILE *) fp, (long) offset, SEEK_SET) != 0) (void) 0;
#endif
  return (size_t) ftell((FILE *) fp);
}

static bool p_rename(const char *from, const char *to) {
  return rename(from, to) == 0;
}

static bool p_remove(const char *path) {
  return remove(path) == 0;
}

static bool p_mkdir(const char *path) {
  return mkdir(path, 0775) == 0;
}

#else

static int p_stat(const char *path, size_t *size, time_t *mtime) {
  (void) path, (void) size, (void) mtime;
  return 0;
}
static void p_list(const char *path, void (*fn)(const char *, void *),
                   void *userdata) {
  (void) path, (void) fn, (void) userdata;
}
static void *p_open(const char *path, int flags) {
  (void) path, (void) flags;
  return NULL;
}
static void p_close(void *fp) {
  (void) fp;
}
static size_t p_read(void *fd, void *buf, size_t len) {
  (void) fd, (void) buf, (void) len;
  return 0;
}
static size_t p_write(void *fd, const void *buf, size_t len) {
  (void) fd, (void) buf, (void) len;
  return 0;
}
static size_t p_seek(void *fd, size_t offset) {
  (void) fd, (void) offset;
  return (size_t) ~0;
}
static bool p_rename(const char *from, const char *to) {
  (void) from, (void) to;
  return false;
}
static bool p_remove(const char *path) {
  (void) path;
  return false;
}
static bool p_mkdir(const char *path) {
  (void) path;
  return false;
}
#endif

struct mg_fs mg_fs_posix = {p_stat,  p_list, p_open,   p_close,  p_read,
                            p_write, p_seek, p_rename, p_remove, p_mkdir};

#ifdef MG_ENABLE_LINES
#line 1 "src/http.c"
#endif













static int mg_ncasecmp(const char *s1, const char *s2, size_t len) {
  int diff = 0;
  if (len > 0) do {
      int c = *s1++, d = *s2++;
      if (c >= 'A' && c <= 'Z') c += 'a' - 'A';
      if (d >= 'A' && d <= 'Z') d += 'a' - 'A';
      diff = c - d;
    } while (diff == 0 && s1[-1] != '\0' && --len > 0);
  return diff;
}

bool mg_to_size_t(struct mg_str str, size_t *val);
bool mg_to_size_t(struct mg_str str, size_t *val) {
  size_t i = 0, max = (size_t) -1, max2 = max / 10, result = 0, ndigits = 0;
  while (i < str.len && (str.buf[i] == ' ' || str.buf[i] == '\t')) i++;
  if (i < str.len && str.buf[i] == '-') return false;
  while (i < str.len && str.buf[i] >= '0' && str.buf[i] <= '9') {
    size_t digit = (size_t) (str.buf[i] - '0');
    if (result > max2) return false;  // Overflow
    result *= 10;
    if (result > max - digit) return false;  // Overflow
    result += digit;
    i++, ndigits++;
  }
  while (i < str.len && (str.buf[i] == ' ' || str.buf[i] == '\t')) i++;
  if (ndigits == 0) return false;  // #2322: Content-Length = 1 * DIGIT
  if (i != str.len) return false;  // Ditto
  *val = (size_t) result;
  return true;
}

// Chunk deletion marker is the MSB in the "processed" counter
#define MG_DMARK ((size_t) 1 << (sizeof(size_t) * 8 - 1))

// Multipart POST example:
// --xyz
// Content-Disposition: form-data; name="val"
//
// abcdef
// --xyz
// Content-Disposition: form-data; name="foo"; filename="a.txt"
// Content-Type: text/plain
//
// hello world
//
// --xyz--
size_t mg_http_next_multipart(struct mg_str body, size_t ofs,
                              struct mg_http_part *part) {
  struct mg_str cd = mg_str_n("Content-Disposition", 19);
  const char *s = body.buf;
  size_t b = ofs, h1, h2, b1, b2, max = body.len;

  // Init part params
  if (part != NULL) part->name = part->filename = part->body = mg_str_n(0, 0);

  // Skip boundary
  while (b + 2 < max && s[b] != '\r' && s[b + 1] != '\n') b++;
  if (b <= ofs || b + 2 >= max) return 0;
  // MG_INFO(("B: %zu %zu [%.*s]", ofs, b - ofs, (int) (b - ofs), s));

  // Skip headers
  h1 = h2 = b + 2;
  for (;;) {
    while (h2 + 2 < max && s[h2] != '\r' && s[h2 + 1] != '\n') h2++;
    if (h2 == h1) break;
    if (h2 + 2 >= max) return 0;
    // MG_INFO(("Header: [%.*s]", (int) (h2 - h1), &s[h1]));
    if (part != NULL && h1 + cd.len + 2 < h2 && s[h1 + cd.len] == ':' &&
        mg_ncasecmp(&s[h1], cd.buf, cd.len) == 0) {
      struct mg_str v = mg_str_n(&s[h1 + cd.len + 2], h2 - (h1 + cd.len + 2));
      part->name = mg_http_get_header_var(v, mg_str_n("name", 4));
      part->filename = mg_http_get_header_var(v, mg_str_n("filename", 8));
    }
    h1 = h2 = h2 + 2;
  }
  b1 = b2 = h2 + 2;
  while (b2 + 2 + (b - ofs) + 2 < max && !(s[b2] == '\r' && s[b2 + 1] == '\n' &&
                                           memcmp(&s[b2 + 2], s, b - ofs) == 0))
    b2++;

  if (b2 + 2 >= max) return 0;
  if (part != NULL) part->body = mg_str_n(&s[b1], b2 - b1);
  // MG_INFO(("Body: [%.*s]", (int) (b2 - b1), &s[b1]));
  return b2 + 2;
}

void mg_http_bauth(struct mg_connection *c, const char *user,
                   const char *pass) {
  struct mg_str u = mg_str(user), p = mg_str(pass);
  size_t need = c->send.len + 36 + (u.len + p.len) * 2;
  if (c->send.size < need) mg_iobuf_resize(&c->send, need);
  if (c->send.size >= need) {
    size_t i, n = 0;
    char *buf = (char *) &c->send.buf[c->send.len];
    memcpy(buf, "Authorization: Basic ", 21);  // DON'T use mg_send!
    for (i = 0; i < u.len; i++) {
      n = mg_base64_update(((unsigned char *) u.buf)[i], buf + 21, n);
    }
    if (p.len > 0) {
      n = mg_base64_update(':', buf + 21, n);
      for (i = 0; i < p.len; i++) {
        n = mg_base64_update(((unsigned char *) p.buf)[i], buf + 21, n);
      }
    }
    n = mg_base64_final(buf + 21, n);
    c->send.len += 21 + (size_t) n + 2;
    memcpy(&c->send.buf[c->send.len - 2], "\r\n", 2);
  } else {
    MG_ERROR(("%lu oom %d->%d ", c->id, (int) c->send.size, (int) need));
  }
}

struct mg_str mg_http_var(struct mg_str buf, struct mg_str name) {
  struct mg_str entry, k, v, result = mg_str_n(NULL, 0);
  while (mg_span(buf, &entry, &buf, '&')) {
    if (mg_span(entry, &k, &v, '=') && name.len == k.len &&
        mg_ncasecmp(name.buf, k.buf, k.len) == 0) {
      result = v;
      break;
    }
  }
  return result;
}

int mg_http_get_var(const struct mg_str *buf, const char *name, char *dst,
                    size_t dst_len) {
  int len;
  if (dst != NULL && dst_len > 0) {
    dst[0] = '\0';  // If destination buffer is valid, always nul-terminate it
  }
  if (dst == NULL || dst_len == 0) {
    len = -2;  // Bad destination
  } else if (buf->buf == NULL || name == NULL || buf->len == 0) {
    len = -1;  // Bad source
  } else {
    struct mg_str v = mg_http_var(*buf, mg_str(name));
    if (v.buf == NULL) {
      len = -4;  // Name does not exist
    } else {
      len = mg_url_decode(v.buf, v.len, dst, dst_len, 1);
      if (len < 0) len = -3;  // Failed to decode
    }
  }
  return len;
}

static bool isx(int c) {
  return (c >= '0' && c <= '9') || (c >= 'a' && c <= 'f') ||
         (c >= 'A' && c <= 'F');
}

int mg_url_decode(const char *src, size_t src_len, char *dst, size_t dst_len,
                  int is_form_url_encoded) {
  size_t i, j;
  for (i = j = 0; i < src_len && j + 1 < dst_len; i++, j++) {
    if (src[i] == '%') {
      // Use `i + 2 < src_len`, not `i < src_len - 2`, note small src_len
      if (i + 2 < src_len && isx(src[i + 1]) && isx(src[i + 2])) {
        mg_str_to_num(mg_str_n(src + i + 1, 2), 16, &dst[j], sizeof(uint8_t));
        i += 2;
      } else {
        return -1;
      }
    } else if (is_form_url_encoded && src[i] == '+') {
      dst[j] = ' ';
    } else {
      dst[j] = src[i];
    }
  }
  if (j < dst_len) dst[j] = '\0';  // Null-terminate the destination
  return i >= src_len && j < dst_len ? (int) j : -1;
}

static bool isok(uint8_t c) {
  return c == '\n' || c == '\r' || c == '\t' || c >= ' ';
}

int mg_http_get_request_len(const unsigned char *buf, size_t buf_len) {
  size_t i;
  for (i = 0; i < buf_len; i++) {
    if (!isok(buf[i])) return -1;
    if ((i > 0 && buf[i] == '\n' && buf[i - 1] == '\n') ||
        (i > 3 && buf[i] == '\n' && buf[i - 1] == '\r' && buf[i - 2] == '\n'))
      return (int) i + 1;
  }
  return 0;
}
struct mg_str *mg_http_get_header(struct mg_http_message *h, const char *name) {
  size_t i, n = strlen(name), max = sizeof(h->headers) / sizeof(h->headers[0]);
  for (i = 0; i < max && h->headers[i].name.len > 0; i++) {
    struct mg_str *k = &h->headers[i].name, *v = &h->headers[i].value;
    if (n == k->len && mg_ncasecmp(k->buf, name, n) == 0) return v;
  }
  return NULL;
}

// Is it a valid utf-8 continuation byte
static bool vcb(uint8_t c) {
  return (c & 0xc0) == 0x80;
}

// Get character length (valid utf-8). Used to parse method, URI, headers
static size_t clen(const char *s, const char *end) {
  const unsigned char *u = (unsigned char *) s, c = *u;
  long n = (long) (end - s);
  if (c > ' ' && c < '~') return 1;  // Usual ascii printed char
  if ((c & 0xe0) == 0xc0 && n > 1 && vcb(u[1])) return 2;  // 2-byte UTF8
  if ((c & 0xf0) == 0xe0 && n > 2 && vcb(u[1]) && vcb(u[2])) return 3;
  if ((c & 0xf8) == 0xf0 && n > 3 && vcb(u[1]) && vcb(u[2]) && vcb(u[3]))
    return 4;
  return 0;
}

// Skip until the newline. Return advanced `s`, or NULL on error
static const char *skiptorn(const char *s, const char *end, struct mg_str *v) {
  v->buf = (char *) s;
  while (s < end && s[0] != '\n' && s[0] != '\r') s++, v->len++;  // To newline
  if (s >= end || (s[0] == '\r' && s[1] != '\n')) return NULL;    // Stray \r
  if (s < end && s[0] == '\r') s++;                               // Skip \r
  if (s >= end || *s++ != '\n') return NULL;                      // Skip \n
  return s;
}

static bool mg_http_parse_headers(const char *s, const char *end,
                                  struct mg_http_header *h, size_t max_hdrs) {
  size_t i, n;
  for (i = 0; i < max_hdrs; i++) {
    struct mg_str k = {NULL, 0}, v = {NULL, 0};
    if (s >= end) return false;
    if (s[0] == '\n' || (s[0] == '\r' && s[1] == '\n')) break;
    k.buf = (char *) s;
    while (s < end && s[0] != ':' && (n = clen(s, end)) > 0) s += n, k.len += n;
    if (k.len == 0) return false;                     // Empty name
    if (s >= end || clen(s, end) == 0) return false;  // Invalid UTF-8
    if (*s++ != ':') return false;  // Invalid, not followed by :
    // if (clen(s, end) == 0) return false;        // Invalid UTF-8
    while (s < end && (s[0] == ' ' || s[0] == '\t')) s++;  // Skip spaces
    if ((s = skiptorn(s, end, &v)) == NULL) return false;
    while (v.len > 0 && (v.buf[v.len - 1] == ' ' || v.buf[v.len - 1] == '\t')) {
      v.len--;  // Trim spaces
    }
    // MG_INFO(("--HH [%.*s] [%.*s]", (int) k.len, k.buf, (int) v.len, v.buf));
    h[i].name = k, h[i].value = v;  // Success. Assign values
  }
  return true;
}

int mg_http_parse(const char *s, size_t len, struct mg_http_message *hm) {
  int is_response, req_len = mg_http_get_request_len((unsigned char *) s, len);
  const char *end = s == NULL ? NULL : s + req_len, *qs;  // Cannot add to NULL
  const struct mg_str *cl;
  size_t n;
  bool version_prefix_valid;

  memset(hm, 0, sizeof(*hm));
  if (req_len <= 0) return req_len;

  hm->message.buf = hm->head.buf = (char *) s;
  hm->body.buf = (char *) end;
  hm->head.len = (size_t) req_len;
  hm->message.len = hm->body.len = (size_t) -1;  // Set body length to infinite

  // Parse request line
  hm->method.buf = (char *) s;
  while (s < end && (n = clen(s, end)) > 0) s += n, hm->method.len += n;
  while (s < end && s[0] == ' ') s++;  // Skip spaces
  hm->uri.buf = (char *) s;
  while (s < end && (n = clen(s, end)) > 0) s += n, hm->uri.len += n;
  while (s < end && s[0] == ' ') s++;  // Skip spaces
  is_response = hm->method.len > 5 &&
                (mg_ncasecmp(hm->method.buf, "HTTP/", 5) == 0);
  if ((s = skiptorn(s, end, &hm->proto)) == NULL) return false;
  // If we're given a version, check that it is HTTP/x.x
  version_prefix_valid = hm->proto.len > 5 &&
                         (mg_ncasecmp(hm->proto.buf, "HTTP/", 5) == 0);
  if (!is_response && hm->proto.len > 0 &&
    (!version_prefix_valid || hm->proto.len != 8 ||
    (hm->proto.buf[5] < '0' || hm->proto.buf[5] > '9') ||
    (hm->proto.buf[6] != '.') ||
    (hm->proto.buf[7] < '0' || hm->proto.buf[7] > '9'))) {
    return -1;
  }

  // If URI contains '?' character, setup query string
  if ((qs = (const char *) memchr(hm->uri.buf, '?', hm->uri.len)) != NULL) {
    hm->query.buf = (char *) qs + 1;
    hm->query.len = (size_t) (&hm->uri.buf[hm->uri.len] - (qs + 1));
    hm->uri.len = (size_t) (qs - hm->uri.buf);
  }

  // Sanity check. Allow protocol/reason to be empty
  // Do this check after hm->method.len and hm->uri.len are finalised
  if (hm->method.len == 0 || hm->uri.len == 0) return -1;

  if (!mg_http_parse_headers(s, end, hm->headers,
                             sizeof(hm->headers) / sizeof(hm->headers[0])))
    return -1;  // error when parsing
  if ((cl = mg_http_get_header(hm, "Content-Length")) != NULL) {
    if (mg_to_size_t(*cl, &hm->body.len) == false) return -1;
    hm->message.len = (size_t) req_len + hm->body.len;
  }

  // mg_http_parse() is used to parse both HTTP requests and HTTP
  // responses. If HTTP response does not have Content-Length set, then
  // body is read until socket is closed, i.e. body.len is infinite (~0).
  //
  // For HTTP requests though, according to
  // http://tools.ietf.org/html/rfc7231#section-8.1.3,
  // only POST and PUT methods have defined body semantics.
  // Therefore, if Content-Length is not specified and methods are
  // not one of PUT or POST, set body length to 0.
  //
  // So, if it is HTTP request, and Content-Length is not set,
  // and method is not (PUT or POST) then reset body length to zero.
  if (hm->body.len == (size_t) ~0 && !is_response &&
      mg_strcasecmp(hm->method, mg_str("PUT")) != 0 &&
      mg_strcasecmp(hm->method, mg_str("POST")) != 0) {
    hm->body.len = 0;
    hm->message.len = (size_t) req_len;
  }

  // The 204 (No content) responses also have 0 body length
  if (hm->body.len == (size_t) ~0 && is_response &&
      mg_strcasecmp(hm->uri, mg_str("204")) == 0) {
    hm->body.len = 0;
    hm->message.len = (size_t) req_len;
  }
  if (hm->message.len < (size_t) req_len) return -1;  // Overflow protection

  return req_len;
}

static void mg_http_vprintf_chunk(struct mg_connection *c, const char *fmt,
                                  va_list *ap) {
  size_t len = c->send.len;
  mg_send(c, "        \r\n", 10);
  mg_vxprintf(mg_pfn_iobuf, &c->send, fmt, ap);
  if (c->send.len >= len + 10) {
    mg_snprintf((char *) c->send.buf + len, 9, "%08lx", c->send.len - len - 10);
    c->send.buf[len + 8] = '\r';
    if (c->send.len == len + 10) c->is_resp = 0;  // Last chunk, reset marker
  }
  mg_send(c, "\r\n", 2);
}

void mg_http_printf_chunk(struct mg_connection *c, const char *fmt, ...) {
  va_list ap;
  va_start(ap, fmt);
  mg_http_vprintf_chunk(c, fmt, &ap);
  va_end(ap);
}

void mg_http_write_chunk(struct mg_connection *c, const char *buf, size_t len) {
  mg_printf(c, "%lx\r\n", (unsigned long) len);
  mg_send(c, buf, len);
  mg_send(c, "\r\n", 2);
  if (len == 0) c->is_resp = 0;
}

// clang-format off
static const char *mg_http_status_code_str(int status_code) {
  switch (status_code) {
    case 100: return "Continue";
    case 101: return "Switching Protocols";
    case 102: return "Processing";
    case 200: return "OK";
    case 201: return "Created";
    case 202: return "Accepted";
    case 203: return "Non-authoritative Information";
    case 204: return "No Content";
    case 205: return "Reset Content";
    case 206: return "Partial Content";
    case 207: return "Multi-Status";
    case 208: return "Already Reported";
    case 226: return "IM Used";
    case 300: return "Multiple Choices";
    case 301: return "Moved Permanently";
    case 302: return "Found";
    case 303: return "See Other";
    case 304: return "Not Modified";
    case 305: return "Use Proxy";
    case 307: return "Temporary Redirect";
    case 308: return "Permanent Redirect";
    case 400: return "Bad Request";
    case 401: return "Unauthorized";
    case 402: return "Payment Required";
    case 403: return "Forbidden";
    case 404: return "Not Found";
    case 405: return "Method Not Allowed";
    case 406: return "Not Acceptable";
    case 407: return "Proxy Authentication Required";
    case 408: return "Request Timeout";
    case 409: return "Conflict";
    case 410: return "Gone";
    case 411: return "Length Required";
    case 412: return "Precondition Failed";
    case 413: return "Payload Too Large";
    case 414: return "Request-URI Too Long";
    case 415: return "Unsupported Media Type";
    case 416: return "Requested Range Not Satisfiable";
    case 417: return "Expectation Failed";
    case 418: return "I'm a teapot";
    case 421: return "Misdirected Request";
    case 422: return "Unprocessable Entity";
    case 423: return "Locked";
    case 424: return "Failed Dependency";
    case 426: return "Upgrade Required";
    case 428: return "Precondition Required";
    case 429: return "Too Many Requests";
    case 431: return "Request Header Fields Too Large";
    case 444: return "Connection Closed Without Response";
    case 451: return "Unavailable For Legal Reasons";
    case 499: return "Client Closed Request";
    case 500: return "Internal Server Error";
    case 501: return "Not Implemented";
    case 502: return "Bad Gateway";
    case 503: return "Service Unavailable";
    case 504: return "Gateway Timeout";
    case 505: return "HTTP Version Not Supported";
    case 506: return "Variant Also Negotiates";
    case 507: return "Insufficient Storage";
    case 508: return "Loop Detected";
    case 510: return "Not Extended";
    case 511: return "Network Authentication Required";
    case 599: return "Network Connect Timeout Error";
    default: return "";
  }
}
// clang-format on

void mg_http_reply(struct mg_connection *c, int code, const char *headers,
                   const char *fmt, ...) {
  va_list ap;
  size_t len;
  mg_printf(c, "HTTP/1.1 %d %s\r\n%sContent-Length:            \r\n\r\n", code,
            mg_http_status_code_str(code), headers == NULL ? "" : headers);
  len = c->send.len;
  va_start(ap, fmt);
  mg_vxprintf(mg_pfn_iobuf, &c->send, fmt, &ap);
  va_end(ap);
  if (c->send.len > 16) {
    size_t n = mg_snprintf((char *) &c->send.buf[len - 15], 11, "%-10lu",
                           (unsigned long) (c->send.len - len));
    c->send.buf[len - 15 + n] = ' ';  // Change ending 0 to space
  }
  c->is_resp = 0;
}

static void http_cb(struct mg_connection *, int, void *);
static void restore_http_cb(struct mg_connection *c) {
  mg_fs_close((struct mg_fd *) c->pfn_data);
  c->pfn_data = NULL;
  c->pfn = http_cb;
  c->is_resp = 0;
}

char *mg_http_etag(char *buf, size_t len, size_t size, time_t mtime);
char *mg_http_etag(char *buf, size_t len, size_t size, time_t mtime) {
  mg_snprintf(buf, len, "\"%lld.%lld\"", (int64_t) mtime, (int64_t) size);
  return buf;
}

static void static_cb(struct mg_connection *c, int ev, void *ev_data) {
  if (ev == MG_EV_WRITE || ev == MG_EV_POLL) {
    struct mg_fd *fd = (struct mg_fd *) c->pfn_data;
    // Read to send IO buffer directly, avoid extra on-stack buffer
    size_t n, max = MG_IO_SIZE, space;
    size_t *cl = (size_t *) &c->data[(sizeof(c->data) - sizeof(size_t)) /
                                     sizeof(size_t) * sizeof(size_t)];
    if (c->send.size < max) mg_iobuf_resize(&c->send, max);
    if (c->send.len >= c->send.size) return;  // Rate limit
    if ((space = c->send.size - c->send.len) > *cl) space = *cl;
    n = fd->fs->rd(fd->fd, c->send.buf + c->send.len, space);
    c->send.len += n;
    *cl -= n;
    if (n == 0) restore_http_cb(c);
  } else if (ev == MG_EV_CLOSE) {
    restore_http_cb(c);
  }
  (void) ev_data;
}

// Known mime types. Keep it outside guess_content_type() function, since
// some environments don't like it defined there.
// clang-format off
#define MG_C_STR(a) { (char *) (a), sizeof(a) - 1 }
static struct mg_str s_known_types[] = {
    MG_C_STR("html"), MG_C_STR("text/html; charset=utf-8"),
    MG_C_STR("htm"), MG_C_STR("text/html; charset=utf-8"),
    MG_C_STR("css"), MG_C_STR("text/css; charset=utf-8"),
    MG_C_STR("js"), MG_C_STR("text/javascript; charset=utf-8"),
    MG_C_STR("mjs"), MG_C_STR("text/javascript; charset=utf-8"),
    MG_C_STR("gif"), MG_C_STR("image/gif"),
    MG_C_STR("png"), MG_C_STR("image/png"),
    MG_C_STR("jpg"), MG_C_STR("image/jpeg"),
    MG_C_STR("jpeg"), MG_C_STR("image/jpeg"),
    MG_C_STR("woff"), MG_C_STR("font/woff"),
    MG_C_STR("ttf"), MG_C_STR("font/ttf"),
    MG_C_STR("svg"), MG_C_STR("image/svg+xml"),
    MG_C_STR("txt"), MG_C_STR("text/plain; charset=utf-8"),
    MG_C_STR("avi"), MG_C_STR("video/x-msvideo"),
    MG_C_STR("csv"), MG_C_STR("text/csv"),
    MG_C_STR("doc"), MG_C_STR("application/msword"),
    MG_C_STR("exe"), MG_C_STR("application/octet-stream"),
    MG_C_STR("gz"), MG_C_STR("application/gzip"),
    MG_C_STR("ico"), MG_C_STR("image/x-icon"),
    MG_C_STR("json"), MG_C_STR("application/json"),
    MG_C_STR("mov"), MG_C_STR("video/quicktime"),
    MG_C_STR("mp3"), MG_C_STR("audio/mpeg"),
    MG_C_STR("mp4"), MG_C_STR("video/mp4"),
    MG_C_STR("mpeg"), MG_C_STR("video/mpeg"),
    MG_C_STR("pdf"), MG_C_STR("application/pdf"),
    MG_C_STR("shtml"), MG_C_STR("text/html; charset=utf-8"),
    MG_C_STR("tgz"), MG_C_STR("application/tar-gz"),
    MG_C_STR("wav"), MG_C_STR("audio/wav"),
    MG_C_STR("webp"), MG_C_STR("image/webp"),
    MG_C_STR("zip"), MG_C_STR("application/zip"),
    MG_C_STR("3gp"), MG_C_STR("video/3gpp"),
    {0, 0},
};
// clang-format on

static struct mg_str guess_content_type(struct mg_str path, const char *extra) {
  struct mg_str entry, k, v, s = mg_str(extra), asterisk = mg_str_n("*", 1);
  size_t i = 0;

  // Shrink path to its extension only
  while (i < path.len && path.buf[path.len - i - 1] != '.') i++;
  path.buf += path.len - i;
  path.len = i;

  // Process user-provided mime type overrides, if any
  while (mg_span(s, &entry, &s, ',')) {
    if (mg_span(entry, &k, &v, '=') &&
        (mg_strcmp(asterisk, k) == 0 || mg_strcmp(path, k) == 0))
      return v;
  }

  // Process built-in mime types
  for (i = 0; s_known_types[i].buf != NULL; i += 2) {
    if (mg_strcmp(path, s_known_types[i]) == 0) return s_known_types[i + 1];
  }

  return mg_str("text/plain; charset=utf-8");
}

static int getrange(struct mg_str *s, size_t *a, size_t *b) {
  size_t i, numparsed = 0;
  for (i = 0; i + 6 < s->len; i++) {
    struct mg_str k, v = mg_str_n(s->buf + i + 6, s->len - i - 6);
    if (memcmp(&s->buf[i], "bytes=", 6) != 0) continue;
    if (mg_span(v, &k, &v, '-')) {
      if (mg_to_size_t(k, a)) numparsed++;
      if (v.len > 0 && mg_to_size_t(v, b)) numparsed++;
    } else {
      if (mg_to_size_t(v, a)) numparsed++;
    }
    break;
  }
  return (int) numparsed;
}

void mg_http_serve_file(struct mg_connection *c, struct mg_http_message *hm,
                        const char *path,
                        const struct mg_http_serve_opts *opts) {
  char etag[64], tmp[MG_PATH_MAX];
  struct mg_fs *fs = opts->fs == NULL ? &mg_fs_posix : opts->fs;
  struct mg_fd *fd = NULL;
  size_t size = 0;
  time_t mtime = 0;
  struct mg_str *inm = NULL;
  struct mg_str mime = guess_content_type(mg_str(path), opts->mime_types);
  bool gzip = false;

  if (path != NULL) {
    // If a browser sends us "Accept-Encoding: gzip", try to open .gz first
    struct mg_str *ae = mg_http_get_header(hm, "Accept-Encoding");
    if (ae != NULL) {
      char *ae_ = mg_mprintf("%.*s", ae->len, ae->buf);
      if (ae_ != NULL && strstr(ae_, "gzip") != NULL) {
        mg_snprintf(tmp, sizeof(tmp), "%s.gz", path);
        fd = mg_fs_open(fs, tmp, MG_FS_READ);
        if (fd != NULL) gzip = true, path = tmp;
      }
      free(ae_);
    }
    // No luck opening .gz? Open what we've told to open
    if (fd == NULL) fd = mg_fs_open(fs, path, MG_FS_READ);
  }

  // Failed to open, and page404 is configured? Open it, then
  if (fd == NULL && opts->page404 != NULL) {
    fd = mg_fs_open(fs, opts->page404, MG_FS_READ);
    path = opts->page404;
    mime = guess_content_type(mg_str(path), opts->mime_types);
  }

  if (fd == NULL || fs->st(path, &size, &mtime) == 0) {
    mg_http_reply(c, 404, opts->extra_headers, "Not found\n");
    mg_fs_close(fd);
    // NOTE: mg_http_etag() call should go first!
  } else if (mg_http_etag(etag, sizeof(etag), size, mtime) != NULL &&
             (inm = mg_http_get_header(hm, "If-None-Match")) != NULL &&
             mg_strcasecmp(*inm, mg_str(etag)) == 0) {
    mg_fs_close(fd);
    mg_http_reply(c, 304, opts->extra_headers, "");
  } else {
    int n, status = 200;
    char range[100];
    size_t r1 = 0, r2 = 0, cl = size;

    // Handle Range header
    struct mg_str *rh = mg_http_get_header(hm, "Range");
    range[0] = '\0';
    if (rh != NULL && (n = getrange(rh, &r1, &r2)) > 0) {
      // If range is specified like "400-", set second limit to content len
      if (n == 1) r2 = cl - 1;
      if (r1 > r2 || r2 >= cl) {
        status = 416;
        cl = 0;
        mg_snprintf(range, sizeof(range), "Content-Range: bytes */%lld\r\n",
                    (int64_t) size);
      } else {
        status = 206;
        cl = r2 - r1 + 1;
        mg_snprintf(range, sizeof(range),
                    "Content-Range: bytes %llu-%llu/%llu\r\n", (uint64_t) r1,
                    (uint64_t) (r1 + cl - 1), (uint64_t) size);
        fs->sk(fd->fd, r1);
      }
    }
    mg_printf(c,
              "HTTP/1.1 %d %s\r\n"
              "Content-Type: %.*s\r\n"
              "Etag: %s\r\n"
              "Content-Length: %llu\r\n"
              "%s%s%s\r\n",
              status, mg_http_status_code_str(status), (int) mime.len, mime.buf,
              etag, (uint64_t) cl, gzip ? "Content-Encoding: gzip\r\n" : "",
              range, opts->extra_headers ? opts->extra_headers : "");
    if (mg_strcasecmp(hm->method, mg_str("HEAD")) == 0) {
      c->is_resp = 0;
      mg_fs_close(fd);
    } else {
      // Track to-be-sent content length at the end of c->data, aligned
      size_t *clp = (size_t *) &c->data[(sizeof(c->data) - sizeof(size_t)) /
                                        sizeof(size_t) * sizeof(size_t)];
      c->pfn = static_cb;
      c->pfn_data = fd;
      *clp = cl;
    }
  }
}

struct printdirentrydata {
  struct mg_connection *c;
  struct mg_http_message *hm;
  const struct mg_http_serve_opts *opts;
  const char *dir;
};

#if MG_ENABLE_DIRLIST
static void printdirentry(const char *name, void *userdata) {
  struct printdirentrydata *d = (struct printdirentrydata *) userdata;
  struct mg_fs *fs = d->opts->fs == NULL ? &mg_fs_posix : d->opts->fs;
  size_t size = 0;
  time_t t = 0;
  char path[MG_PATH_MAX], sz[40], mod[40];
  int flags, n = 0;

  // MG_DEBUG(("[%s] [%s]", d->dir, name));
  if (mg_snprintf(path, sizeof(path), "%s%c%s", d->dir, '/', name) >
      sizeof(path)) {
    MG_ERROR(("%s truncated", name));
  } else if ((flags = fs->st(path, &size, &t)) == 0) {
    MG_ERROR(("%lu stat(%s): %d", d->c->id, path, errno));
  } else {
    const char *slash = flags & MG_FS_DIR ? "/" : "";
    if (flags & MG_FS_DIR) {
      mg_snprintf(sz, sizeof(sz), "%s", "[DIR]");
    } else {
      mg_snprintf(sz, sizeof(sz), "%lld", (uint64_t) size);
    }
#if defined(MG_HTTP_DIRLIST_TIME_FMT)
    {
      char time_str[40];
      struct tm *time_info = localtime(&t);
      strftime(time_str, sizeof time_str, "%Y/%m/%d %H:%M:%S", time_info);
      mg_snprintf(mod, sizeof(mod), "%s", time_str);
    }
#else
    mg_snprintf(mod, sizeof(mod), "%lu", (unsigned long) t);
#endif
    n = (int) mg_url_encode(name, strlen(name), path, sizeof(path));
    mg_printf(d->c,
              "  <tr><td><a href=\"%.*s%s\">%s%s</a></td>"
              "<td name=%lu>%s</td><td name=%lld>%s</td></tr>\n",
              n, path, slash, name, slash, (unsigned long) t, mod,
              flags & MG_FS_DIR ? (int64_t) -1 : (int64_t) size, sz);
  }
}

static void listdir(struct mg_connection *c, struct mg_http_message *hm,
                    const struct mg_http_serve_opts *opts, char *dir) {
  const char *sort_js_code =
      "<script>function srt(tb, sc, so, d) {"
      "var tr = Array.prototype.slice.call(tb.rows, 0),"
      "tr = tr.sort(function (a, b) { var c1 = a.cells[sc], c2 = b.cells[sc],"
      "n1 = c1.getAttribute('name'), n2 = c2.getAttribute('name'), "
      "t1 = a.cells[2].getAttribute('name'), "
      "t2 = b.cells[2].getAttribute('name'); "
      "return so * (t1 < 0 && t2 >= 0 ? -1 : t2 < 0 && t1 >= 0 ? 1 : "
      "n1 ? parseInt(n2) - parseInt(n1) : "
      "c1.textContent.trim().localeCompare(c2.textContent.trim())); });";
  const char *sort_js_code2 =
      "for (var i = 0; i < tr.length; i++) tb.appendChild(tr[i]); "
      "if (!d) window.location.hash = ('sc=' + sc + '&so=' + so); "
      "};"
      "window.onload = function() {"
      "var tb = document.getElementById('tb');"
      "var m = /sc=([012]).so=(1|-1)/.exec(window.location.hash) || [0, 2, 1];"
      "var sc = m[1], so = m[2]; document.onclick = function(ev) { "
      "var c = ev.target.rel; if (c) {if (c == sc) so *= -1; srt(tb, c, so); "
      "sc = c; ev.preventDefault();}};"
      "srt(tb, sc, so, true);"
      "}"
      "</script>";
  struct mg_fs *fs = opts->fs == NULL ? &mg_fs_posix : opts->fs;
  struct printdirentrydata d = {c, hm, opts, dir};
  char tmp[10], buf[MG_PATH_MAX];
  size_t off, n;
  int len = mg_url_decode(hm->uri.buf, hm->uri.len, buf, sizeof(buf), 0);
  struct mg_str uri = len > 0 ? mg_str_n(buf, (size_t) len) : hm->uri;

  mg_printf(c,
            "HTTP/1.1 200 OK\r\n"
            "Content-Type: text/html; charset=utf-8\r\n"
            "%s"
            "Content-Length:         \r\n\r\n",
            opts->extra_headers == NULL ? "" : opts->extra_headers);
  off = c->send.len;  // Start of body
  mg_printf(c,
            "<!DOCTYPE html><html><head><title>Index of %.*s</title>%s%s"
            "<style>th,td {text-align: left; padding-right: 1em; "
            "font-family: monospace; }</style></head>"
            "<body><h1>Index of %.*s</h1><table cellpadding=\"0\"><thead>"
            "<tr><th><a href=\"#\" rel=\"0\">Name</a></th><th>"
            "<a href=\"#\" rel=\"1\">Modified</a></th>"
            "<th><a href=\"#\" rel=\"2\">Size</a></th></tr>"
            "<tr><td colspan=\"3\"><hr></td></tr>"
            "</thead>"
            "<tbody id=\"tb\">\n",
            (int) uri.len, uri.buf, sort_js_code, sort_js_code2, (int) uri.len,
            uri.buf);
  mg_printf(c, "%s",
            "  <tr><td><a href=\"..\">..</a></td>"
            "<td name=-1></td><td name=-1>[DIR]</td></tr>\n");

  fs->ls(dir, printdirentry, &d);
  mg_printf(c,
            "</tbody><tfoot><tr><td colspan=\"3\"><hr></td></tr></tfoot>"
            "</table><address>Mongoose v.%s</address></body></html>\n",
            MG_VERSION);
  n = mg_snprintf(tmp, sizeof(tmp), "%lu", (unsigned long) (c->send.len - off));
  if (n > sizeof(tmp)) n = 0;
  memcpy(c->send.buf + off - 12, tmp, n);  // Set content length
  c->is_resp = 0;                          // Mark response end
}
#endif

// Resolve requested file into `path` and return its fs->st() result
static int uri_to_path2(struct mg_connection *c, struct mg_http_message *hm,
                        struct mg_fs *fs, struct mg_str url, struct mg_str dir,
                        char *path, size_t path_size) {
  int flags, tmp;
  // Append URI to the root_dir, and sanitize it
  size_t n = mg_snprintf(path, path_size, "%.*s", (int) dir.len, dir.buf);
  if (n + 2 >= path_size) {
    mg_http_reply(c, 400, "", "Exceeded path size");
    return -1;
  }
  path[path_size - 1] = '\0';
  // Terminate root dir with slash
  if (n > 0 && path[n - 1] != '/') path[n++] = '/', path[n] = '\0';
  if (url.len < hm->uri.len) {
    mg_url_decode(hm->uri.buf + url.len, hm->uri.len - url.len, path + n,
                  path_size - n, 0);
  }
  path[path_size - 1] = '\0';  // Double-check
  if (!mg_path_is_sane(mg_str_n(path, path_size))) {
    mg_http_reply(c, 400, "", "Invalid path");
    return -1;
  }
  n = strlen(path);
  while (n > 1 && path[n - 1] == '/') path[--n] = 0;  // Trim trailing slashes
  flags = mg_strcmp(hm->uri, mg_str("/")) == 0 ? MG_FS_DIR
                                               : fs->st(path, NULL, NULL);
  MG_VERBOSE(("%lu %.*s -> %s %d", c->id, (int) hm->uri.len, hm->uri.buf, path,
              flags));
  if (flags == 0) {
    // Do nothing - let's caller decide
  } else if ((flags & MG_FS_DIR) && hm->uri.len > 0 &&
             hm->uri.buf[hm->uri.len - 1] != '/') {
    mg_printf(c,
              "HTTP/1.1 301 Moved\r\n"
              "Location: %.*s/\r\n"
              "Content-Length: 0\r\n"
              "\r\n",
              (int) hm->uri.len, hm->uri.buf);
    c->is_resp = 0;
    flags = -1;
  } else if (flags & MG_FS_DIR) {
    if (((mg_snprintf(path + n, path_size - n, "/" MG_HTTP_INDEX) > 0 &&
          (tmp = fs->st(path, NULL, NULL)) != 0) ||
         (mg_snprintf(path + n, path_size - n, "/index.shtml") > 0 &&
          (tmp = fs->st(path, NULL, NULL)) != 0))) {
      flags = tmp;
    } else if ((mg_snprintf(path + n, path_size - n, "/" MG_HTTP_INDEX ".gz") >
                    0 &&
                (tmp = fs->st(path, NULL, NULL)) !=
                    0)) {  // check for gzipped index
      flags = tmp;
      path[n + 1 + strlen(MG_HTTP_INDEX)] =
          '\0';  // Remove appended .gz in index file name
    } else {
      path[n] = '\0';  // Remove appended index file name
    }
  }
  return flags;
}

static int uri_to_path(struct mg_connection *c, struct mg_http_message *hm,
                       const struct mg_http_serve_opts *opts, char *path,
                       size_t path_size) {
  struct mg_fs *fs = opts->fs == NULL ? &mg_fs_posix : opts->fs;
  struct mg_str k, v, part, s = mg_str(opts->root_dir), u = {NULL, 0}, p = u;
  while (mg_span(s, &part, &s, ',')) {
    if (!mg_span(part, &k, &v, '=')) k = part, v = mg_str_n(NULL, 0);
    if (v.len == 0) v = k, k = mg_str("/"), u = k, p = v;
    if (hm->uri.len < k.len) continue;
    if (mg_strcmp(k, mg_str_n(hm->uri.buf, k.len)) != 0) continue;
    u = k, p = v;
  }
  return uri_to_path2(c, hm, fs, u, p, path, path_size);
}

void mg_http_serve_dir(struct mg_connection *c, struct mg_http_message *hm,
                       const struct mg_http_serve_opts *opts) {
  char path[MG_PATH_MAX];
  const char *sp = opts->ssi_pattern;
  int flags = uri_to_path(c, hm, opts, path, sizeof(path));
  if (flags < 0) {
    // Do nothing: the response has already been sent by uri_to_path()
  } else if (flags & MG_FS_DIR) {
#if MG_ENABLE_DIRLIST
    listdir(c, hm, opts, path);
#else
    mg_http_reply(c, 403, "", "Forbidden\n");
#endif
  } else if (flags && sp != NULL && mg_match(mg_str(path), mg_str(sp), NULL)) {
    mg_http_serve_ssi(c, opts->root_dir, path);
  } else {
    mg_http_serve_file(c, hm, path, opts);
  }
}

static bool mg_is_url_safe(int c) {
  return (c >= '0' && c <= '9') || (c >= 'a' && c <= 'z') ||
         (c >= 'A' && c <= 'Z') || c == '.' || c == '_' || c == '-' || c == '~';
}

size_t mg_url_encode(const char *s, size_t sl, char *buf, size_t len) {
  size_t i, n = 0;
  for (i = 0; i < sl; i++) {
    int c = *(unsigned char *) &s[i];
    if (n + 4 >= len) return 0;
    if (mg_is_url_safe(c)) {
      buf[n++] = s[i];
    } else {
      mg_snprintf(&buf[n], 4, "%%%M", mg_print_hex, 1, &s[i]);
      n += 3;
    }
  }
  if (len > 0 && n < len - 1) buf[n] = '\0';  // Null-terminate the destination
  if (len > 0) buf[len - 1] = '\0';           // Always.
  return n;
}

void mg_http_creds(struct mg_http_message *hm, char *user, size_t userlen,
                   char *pass, size_t passlen) {
  struct mg_str *v = mg_http_get_header(hm, "Authorization");
  user[0] = pass[0] = '\0';
  if (v != NULL && v->len > 6 && memcmp(v->buf, "Basic ", 6) == 0) {
    char buf[256];
    size_t n = mg_base64_decode(v->buf + 6, v->len - 6, buf, sizeof(buf));
    const char *p = (const char *) memchr(buf, ':', n > 0 ? n : 0);
    if (p != NULL) {
      mg_snprintf(user, userlen, "%.*s", p - buf, buf);
      mg_snprintf(pass, passlen, "%.*s", n - (size_t) (p - buf) - 1, p + 1);
    }
  } else if (v != NULL && v->len > 7 && memcmp(v->buf, "Bearer ", 7) == 0) {
    mg_snprintf(pass, passlen, "%.*s", (int) v->len - 7, v->buf + 7);
  } else if ((v = mg_http_get_header(hm, "Cookie")) != NULL) {
    struct mg_str t = mg_http_get_header_var(*v, mg_str_n("access_token", 12));
    if (t.len > 0) mg_snprintf(pass, passlen, "%.*s", (int) t.len, t.buf);
  } else {
    mg_http_get_var(&hm->query, "access_token", pass, passlen);
  }
}

static struct mg_str stripquotes(struct mg_str s) {
  return s.len > 1 && s.buf[0] == '"' && s.buf[s.len - 1] == '"'
             ? mg_str_n(s.buf + 1, s.len - 2)
             : s;
}

struct mg_str mg_http_get_header_var(struct mg_str s, struct mg_str v) {
  size_t i;
  for (i = 0; v.len > 0 && i + v.len + 2 < s.len; i++) {
    if (s.buf[i + v.len] == '=' && memcmp(&s.buf[i], v.buf, v.len) == 0) {
      const char *p = &s.buf[i + v.len + 1], *b = p, *x = &s.buf[s.len];
      int q = p < x && *p == '"' ? 1 : 0;
      while (p < x &&
             (q ? p == b || *p != '"' : *p != ';' && *p != ' ' && *p != ','))
        p++;
      // MG_INFO(("[%.*s] [%.*s] [%.*s]", (int) s.len, s.buf, (int) v.len,
      // v.buf, (int) (p - b), b));
      return stripquotes(mg_str_n(b, (size_t) (p - b + q)));
    }
  }
  return mg_str_n(NULL, 0);
}

long mg_http_upload(struct mg_connection *c, struct mg_http_message *hm,
                    struct mg_fs *fs, const char *dir, size_t max_size) {
  char buf[20] = "0", file[MG_PATH_MAX], path[MG_PATH_MAX];
  long res = 0, offset;
  mg_http_get_var(&hm->query, "offset", buf, sizeof(buf));
  mg_http_get_var(&hm->query, "file", file, sizeof(file));
  offset = strtol(buf, NULL, 0);
  mg_snprintf(path, sizeof(path), "%s%c%s", dir, MG_DIRSEP, file);
  if (hm->body.len == 0) {
    mg_http_reply(c, 200, "", "%ld", res);  // Nothing to write
  } else if (file[0] == '\0') {
    mg_http_reply(c, 400, "", "file required");
    res = -1;
  } else if (mg_path_is_sane(mg_str(file)) == false) {
    mg_http_reply(c, 400, "", "%s: invalid file", file);
    res = -2;
  } else if (offset < 0) {
    mg_http_reply(c, 400, "", "offset required");
    res = -3;
  } else if ((size_t) offset + hm->body.len > max_size) {
    mg_http_reply(c, 400, "", "%s: over max size of %lu", path,
                  (unsigned long) max_size);
    res = -4;
  } else {
    struct mg_fd *fd;
    size_t current_size = 0;
    MG_DEBUG(("%s -> %lu bytes @ %ld", path, hm->body.len, offset));
    if (offset == 0) fs->rm(path);  // If offset if 0, truncate file
    fs->st(path, &current_size, NULL);
    if (offset > 0 && current_size != (size_t) offset) {
      mg_http_reply(c, 400, "", "%s: offset mismatch", path);
      res = -5;
    } else if ((fd = mg_fs_open(fs, path, MG_FS_WRITE)) == NULL) {
      mg_http_reply(c, 400, "", "open(%s): %d", path, errno);
      res = -6;
    } else {
      res = offset + (long) fs->wr(fd->fd, hm->body.buf, hm->body.len);
      mg_fs_close(fd);
      mg_http_reply(c, 200, "", "%ld", res);
    }
  }
  return res;
}

int mg_http_status(const struct mg_http_message *hm) {
  return atoi(hm->uri.buf);
}

static bool is_hex_digit(int c) {
  return (c >= '0' && c <= '9') || (c >= 'a' && c <= 'f') ||
         (c >= 'A' && c <= 'F');
}

static int skip_chunk(const char *buf, int len, int *pl, int *dl) {
  int i = 0, n = 0;
  if (len < 3) return 0;
  while (i < len && is_hex_digit(buf[i])) i++;
  if (i == 0) return -1;                     // Error, no length specified
  if (i > (int) sizeof(int) * 2) return -1;  // Chunk length is too big
  if (len < i + 1 || buf[i] != '\r' || buf[i + 1] != '\n') return -1;  // Error
  if (mg_str_to_num(mg_str_n(buf, (size_t) i), 16, &n, sizeof(int)) == false)
    return -1;                    // Decode chunk length, overflow
  if (n < 0) return -1;           // Error. TODO(): some checks now redundant
  if (n > len - i - 4) return 0;  // Chunk not yet fully buffered
  if (buf[i + n + 2] != '\r' || buf[i + n + 3] != '\n') return -1;  // Error
  *pl = i + 2, *dl = n;
  return i + 2 + n + 2;
}

static void http_cb(struct mg_connection *c, int ev, void *ev_data) {
  if (ev == MG_EV_READ || ev == MG_EV_CLOSE ||
      (ev == MG_EV_POLL && c->is_accepted && !c->is_draining &&
       c->recv.len > 0)) {  // see #2796
    struct mg_http_message hm;
    size_t ofs = 0;  // Parsing offset
    while (c->is_resp == 0 && ofs < c->recv.len) {
      const char *buf = (char *) c->recv.buf + ofs;
      int n = mg_http_parse(buf, c->recv.len - ofs, &hm);
      struct mg_str *te;  // Transfer - encoding header
      bool is_chunked = false;
      size_t old_len = c->recv.len;
      if (n < 0) {
        // We don't use mg_error() here, to avoid closing pipelined requests
        // prematurely, see #2592
        MG_ERROR(("HTTP parse, %lu bytes", c->recv.len));
        c->is_draining = 1;
        mg_hexdump(buf, c->recv.len - ofs > 16 ? 16 : c->recv.len - ofs);
        c->recv.len = 0;
        return;
      }
      if (n == 0) break;                 // Request is not buffered yet
      mg_call(c, MG_EV_HTTP_HDRS, &hm);  // Got all HTTP headers
      if (c->recv.len != old_len) {
        // User manipulated received data. Wash our hands
        MG_DEBUG(("%lu detaching HTTP handler", c->id));
        c->pfn = NULL;
        return;
      }
      if (ev == MG_EV_CLOSE) {           // If client did not set Content-Length
        hm.message.len = c->recv.len - ofs;  // and closes now, deliver MSG
        hm.body.len = hm.message.len - (size_t) (hm.body.buf - hm.message.buf);
      }
      if ((te = mg_http_get_header(&hm, "Transfer-Encoding")) != NULL) {
        if (mg_strcasecmp(*te, mg_str("chunked")) == 0) {
          is_chunked = true;
        } else {
          mg_error(c, "Invalid Transfer-Encoding");  // See #2460
          return;
        }
      } else if (mg_http_get_header(&hm, "Content-length") == NULL) {
        // #2593: HTTP packets must contain either Transfer-Encoding or
        // Content-length
        bool is_response = mg_ncasecmp(hm.method.buf, "HTTP/", 5) == 0;
        bool require_content_len = false;
        if (!is_response && (mg_strcasecmp(hm.method, mg_str("POST")) == 0 ||
                             mg_strcasecmp(hm.method, mg_str("PUT")) == 0)) {
          // POST and PUT should include an entity body. Therefore, they should
          // contain a Content-length header. Other requests can also contain a
          // body, but their content has no defined semantics (RFC 7231)
          require_content_len = true;
          ofs += (size_t) n;  // this request has been processed
        } else if (is_response) {
          // HTTP spec 7.2 Entity body: All other responses must include a body
          // or Content-Length header field defined with a value of 0.
          int status = mg_http_status(&hm);
          require_content_len = status >= 200 && status != 204 && status != 304;
        }
        if (require_content_len) {
          if (!c->is_client) mg_http_reply(c, 411, "", "");
          MG_ERROR(("Content length missing from %s", is_response ? "response" : "request"));
        }
      }

      if (is_chunked) {
        // For chunked data, strip off prefixes and suffixes from chunks
        // and relocate them right after the headers, then report a message
        char *s = (char *) c->recv.buf + ofs + n;
        int o = 0, pl, dl, cl, len = (int) (c->recv.len - ofs - (size_t) n);

        // Find zero-length chunk (the end of the body)
        while ((cl = skip_chunk(s + o, len - o, &pl, &dl)) > 0 && dl) o += cl;
        if (cl == 0) break;  // No zero-len chunk, buffer more data
        if (cl < 0) {
          mg_error(c, "Invalid chunk");
          break;
        }

        // Zero chunk found. Second pass: strip + relocate
        o = 0, hm.body.len = 0, hm.message.len = (size_t) n;
        while ((cl = skip_chunk(s + o, len - o, &pl, &dl)) > 0) {
          memmove(s + hm.body.len, s + o + pl, (size_t) dl);
          o += cl, hm.body.len += (size_t) dl, hm.message.len += (size_t) dl;
          if (dl == 0) break;
        }
        ofs += (size_t) (n + o);
      } else {  // Normal, non-chunked data
        size_t len = c->recv.len - ofs - (size_t) n;
        if (hm.body.len > len) break;  // Buffer more data
        ofs += (size_t) n + hm.body.len;
      }

      if (c->is_accepted) c->is_resp = 1;  // Start generating response
      mg_call(c, MG_EV_HTTP_MSG, &hm);     // User handler can clear is_resp
      if (c->is_accepted && !c->is_resp) {
        struct mg_str *cc = mg_http_get_header(&hm, "Connection");
        if (cc != NULL && mg_strcasecmp(*cc, mg_str("close")) == 0) {
          c->is_draining = 1;  // honor "Connection: close"
          break;
        }
      }
    }
    if (ofs > 0) mg_iobuf_del(&c->recv, 0, ofs);  // Delete processed data
  }
  (void) ev_data;
}

static void mg_hfn(struct mg_connection *c, int ev, void *ev_data) {
  if (ev == MG_EV_HTTP_MSG) {
    struct mg_http_message *hm = (struct mg_http_message *) ev_data;
    if (mg_match(hm->uri, mg_str("/quit"), NULL)) {
      mg_http_reply(c, 200, "", "ok\n");
      c->is_draining = 1;
      c->data[0] = 'X';
    } else if (mg_match(hm->uri, mg_str("/debug"), NULL)) {
      int level = (int) mg_json_get_long(hm->body, "$.level", MG_LL_DEBUG);
      mg_log_set(level);
      mg_http_reply(c, 200, "", "Debug level set to %d\n", level);
    } else {
      mg_http_reply(c, 200, "", "hi\n");
    }
  } else if (ev == MG_EV_CLOSE) {
    if (c->data[0] == 'X') *(bool *) c->fn_data = true;
  }
}

void mg_hello(const char *url) {
  struct mg_mgr mgr;
  bool done = false;
  mg_mgr_init(&mgr);
  if (mg_http_listen(&mgr, url, mg_hfn, &done) == NULL) done = true;
  while (done == false) mg_mgr_poll(&mgr, 100);
  mg_mgr_free(&mgr);
}

struct mg_connection *mg_http_connect(struct mg_mgr *mgr, const char *url,
                                      mg_event_handler_t fn, void *fn_data) {
  struct mg_connection *c = mg_connect(mgr, url, fn, fn_data);
  if (c != NULL) c->pfn = http_cb;
  return c;
}

struct mg_connection *mg_http_listen(struct mg_mgr *mgr, const char *url,
                                     mg_event_handler_t fn, void *fn_data) {
  struct mg_connection *c = mg_listen(mgr, url, fn, fn_data);
  if (c != NULL) c->pfn = http_cb;
  return c;
}

#ifdef MG_ENABLE_LINES
#line 1 "src/iobuf.c"
#endif





static size_t roundup(size_t size, size_t align) {
  return align == 0 ? size : (size + align - 1) / align * align;
}

int mg_iobuf_resize(struct mg_iobuf *io, size_t new_size) {
  int ok = 1;
  new_size = roundup(new_size, io->align);
  if (new_size == 0) {
    mg_bzero(io->buf, io->size);
    free(io->buf);
    io->buf = NULL;
    io->len = io->size = 0;
  } else if (new_size != io->size) {
    // NOTE(lsm): do not use realloc here. Use calloc/free only, to ease the
    // porting to some obscure platforms like FreeRTOS
    void *p = calloc(1, new_size);
    if (p != NULL) {
      size_t len = new_size < io->len ? new_size : io->len;
      if (len > 0 && io->buf != NULL) memmove(p, io->buf, len);
      mg_bzero(io->buf, io->size);
      free(io->buf);
      io->buf = (unsigned char *) p;
      io->size = new_size;
    } else {
      ok = 0;
      MG_ERROR(("%lld->%lld", (uint64_t) io->size, (uint64_t) new_size));
    }
  }
  return ok;
}

int mg_iobuf_init(struct mg_iobuf *io, size_t size, size_t align) {
  io->buf = NULL;
  io->align = align;
  io->size = io->len = 0;
  return mg_iobuf_resize(io, size);
}

size_t mg_iobuf_add(struct mg_iobuf *io, size_t ofs, const void *buf,
                    size_t len) {
  size_t new_size = roundup(io->len + len, io->align);
  mg_iobuf_resize(io, new_size);      // Attempt to resize
  if (new_size != io->size) len = 0;  // Resize failure, append nothing
  if (ofs < io->len) memmove(io->buf + ofs + len, io->buf + ofs, io->len - ofs);
  if (buf != NULL) memmove(io->buf + ofs, buf, len);
  if (ofs > io->len) io->len += ofs - io->len;
  io->len += len;
  return len;
}

size_t mg_iobuf_del(struct mg_iobuf *io, size_t ofs, size_t len) {
  if (ofs > io->len) ofs = io->len;
  if (ofs + len > io->len) len = io->len - ofs;
  if (io->buf) memmove(io->buf + ofs, io->buf + ofs + len, io->len - ofs - len);
  if (io->buf) mg_bzero(io->buf + io->len - len, len);
  io->len -= len;
  return len;
}

void mg_iobuf_free(struct mg_iobuf *io) {
  mg_iobuf_resize(io, 0);
}

#ifdef MG_ENABLE_LINES
#line 1 "src/json.c"
#endif




static const char *escapeseq(int esc) {
  return esc ? "\b\f\n\r\t\\\"" : "bfnrt\\\"";
}

static char json_esc(int c, int esc) {
  const char *p, *esc1 = escapeseq(esc), *esc2 = escapeseq(!esc);
  for (p = esc1; *p != '\0'; p++) {
    if (*p == c) return esc2[p - esc1];
  }
  return 0;
}

static int mg_pass_string(const char *s, int len) {
  int i;
  for (i = 0; i < len; i++) {
    if (s[i] == '\\' && i + 1 < len && json_esc(s[i + 1], 1)) {
      i++;
    } else if (s[i] == '\0') {
      return MG_JSON_INVALID;
    } else if (s[i] == '"') {
      return i;
    }
  }
  return MG_JSON_INVALID;
}

static double mg_atod(const char *p, int len, int *numlen) {
  double d = 0.0;
  int i = 0, sign = 1;

  // Sign
  if (i < len && *p == '-') {
    sign = -1, i++;
  } else if (i < len && *p == '+') {
    i++;
  }

  // Decimal
  for (; i < len && p[i] >= '0' && p[i] <= '9'; i++) {
    d *= 10.0;
    d += p[i] - '0';
  }
  d *= sign;

  // Fractional
  if (i < len && p[i] == '.') {
    double frac = 0.0, base = 0.1;
    i++;
    for (; i < len && p[i] >= '0' && p[i] <= '9'; i++) {
      frac += base * (p[i] - '0');
      base /= 10.0;
    }
    d += frac * sign;
  }

  // Exponential
  if (i < len && (p[i] == 'e' || p[i] == 'E')) {
    int j, exp = 0, minus = 0;
    i++;
    if (i < len && p[i] == '-') minus = 1, i++;
    if (i < len && p[i] == '+') i++;
    while (i < len && p[i] >= '0' && p[i] <= '9' && exp < 308)
      exp = exp * 10 + (p[i++] - '0');
    if (minus) exp = -exp;
    for (j = 0; j < exp; j++) d *= 10.0;
    for (j = 0; j < -exp; j++) d /= 10.0;
  }

  if (numlen != NULL) *numlen = i;
  return d;
}

// Iterate over object or array elements
size_t mg_json_next(struct mg_str obj, size_t ofs, struct mg_str *key,
                    struct mg_str *val) {
  if (ofs >= obj.len) {
    ofs = 0;  // Out of boundaries, stop scanning
  } else if (obj.len < 2 || (*obj.buf != '{' && *obj.buf != '[')) {
    ofs = 0;  // Not an array or object, stop
  } else {
    struct mg_str sub = mg_str_n(obj.buf + ofs, obj.len - ofs);
    if (ofs == 0) ofs++, sub.buf++, sub.len--;
    if (*obj.buf == '[') {  // Iterate over an array
      int n = 0, o = mg_json_get(sub, "$", &n);
      if (n < 0 || o < 0 || (size_t) (o + n) > sub.len) {
        ofs = 0;  // Error parsing key, stop scanning
      } else {
        if (key) *key = mg_str_n(NULL, 0);
        if (val) *val = mg_str_n(sub.buf + o, (size_t) n);
        ofs = (size_t) (&sub.buf[o + n] - obj.buf);
      }
    } else {  // Iterate over an object
      int n = 0, o = mg_json_get(sub, "$", &n);
      if (n < 0 || o < 0 || (size_t) (o + n) > sub.len) {
        ofs = 0;  // Error parsing key, stop scanning
      } else {
        if (key) *key = mg_str_n(sub.buf + o, (size_t) n);
        sub.buf += o + n, sub.len -= (size_t) (o + n);
        while (sub.len > 0 && *sub.buf != ':') sub.len--, sub.buf++;
        if (sub.len > 0 && *sub.buf == ':') sub.len--, sub.buf++;
        n = 0, o = mg_json_get(sub, "$", &n);
        if (n < 0 || o < 0 || (size_t) (o + n) > sub.len) {
          ofs = 0;  // Error parsing value, stop scanning
        } else {
          if (val) *val = mg_str_n(sub.buf + o, (size_t) n);
          ofs = (size_t) (&sub.buf[o + n] - obj.buf);
        }
      }
    }
    // MG_INFO(("SUB ofs %u %.*s", ofs, sub.len, sub.buf));
    while (ofs && ofs < obj.len &&
           (obj.buf[ofs] == ' ' || obj.buf[ofs] == '\t' ||
            obj.buf[ofs] == '\n' || obj.buf[ofs] == '\r')) {
      ofs++;
    }
    if (ofs && ofs < obj.len && obj.buf[ofs] == ',') ofs++;
    if (ofs > obj.len) ofs = 0;
  }
  return ofs;
}

int mg_json_get(struct mg_str json, const char *path, int *toklen) {
  const char *s = json.buf;
  int len = (int) json.len;
  enum { S_VALUE, S_KEY, S_COLON, S_COMMA_OR_EOO } expecting = S_VALUE;
  unsigned char nesting[MG_JSON_MAX_DEPTH];
  int i = 0;             // Current offset in `s`
  int j = 0;             // Offset in `s` we're looking for (return value)
  int depth = 0;         // Current depth (nesting level)
  int ed = 0;            // Expected depth
  int pos = 1;           // Current position in `path`
  int ci = -1, ei = -1;  // Current and expected index in array

  if (toklen) *toklen = 0;
  if (path[0] != '$') return MG_JSON_INVALID;

#define MG_CHECKRET(x)                                  \
  do {                                                  \
    if (depth == ed && path[pos] == '\0' && ci == ei) { \
      if (toklen) *toklen = i - j + 1;                  \
      return j;                                         \
    }                                                   \
  } while (0)

// In the ascii table, the distance between `[` and `]` is 2.
// Ditto for `{` and `}`. Hence +2 in the code below.
#define MG_EOO(x)                                            \
  do {                                                       \
    if (depth == ed && ci != ei) return MG_JSON_NOT_FOUND;   \
    if (c != nesting[depth - 1] + 2) return MG_JSON_INVALID; \
    depth--;                                                 \
    MG_CHECKRET(x);                                          \
  } while (0)

  for (i = 0; i < len; i++) {
    unsigned char c = ((unsigned char *) s)[i];
    if (c == ' ' || c == '\t' || c == '\n' || c == '\r') continue;
    switch (expecting) {
      case S_VALUE:
        // p("V %s [%.*s] %d %d %d %d\n", path, pos, path, depth, ed, ci, ei);
        if (depth == ed) j = i;
        if (c == '{') {
          if (depth >= (int) sizeof(nesting)) return MG_JSON_TOO_DEEP;
          if (depth == ed && path[pos] == '.' && ci == ei) {
            // If we start the object, reset array indices
            ed++, pos++, ci = ei = -1;
          }
          nesting[depth++] = c;
          expecting = S_KEY;
          break;
        } else if (c == '[') {
          if (depth >= (int) sizeof(nesting)) return MG_JSON_TOO_DEEP;
          if (depth == ed && path[pos] == '[' && ei == ci) {
            ed++, pos++, ci = 0;
            for (ei = 0; path[pos] != ']' && path[pos] != '\0'; pos++) {
              ei *= 10;
              ei += path[pos] - '0';
            }
            if (path[pos] != 0) pos++;
          }
          nesting[depth++] = c;
          break;
        } else if (c == ']' && depth > 0) {  // Empty array
          MG_EOO(']');
        } else if (c == 't' && i + 3 < len && memcmp(&s[i], "true", 4) == 0) {
          i += 3;
        } else if (c == 'n' && i + 3 < len && memcmp(&s[i], "null", 4) == 0) {
          i += 3;
        } else if (c == 'f' && i + 4 < len && memcmp(&s[i], "false", 5) == 0) {
          i += 4;
        } else if (c == '-' || ((c >= '0' && c <= '9'))) {
          int numlen = 0;
          mg_atod(&s[i], len - i, &numlen);
          i += numlen - 1;
        } else if (c == '"') {
          int n = mg_pass_string(&s[i + 1], len - i - 1);
          if (n < 0) return n;
          i += n + 1;
        } else {
          return MG_JSON_INVALID;
        }
        MG_CHECKRET('V');
        if (depth == ed && ei >= 0) ci++;
        expecting = S_COMMA_OR_EOO;
        break;

      case S_KEY:
        if (c == '"') {
          int n = mg_pass_string(&s[i + 1], len - i - 1);
          if (n < 0) return n;
          if (i + 1 + n >= len) return MG_JSON_NOT_FOUND;
          if (depth < ed) return MG_JSON_NOT_FOUND;
          if (depth == ed && path[pos - 1] != '.') return MG_JSON_NOT_FOUND;
          // printf("K %s [%.*s] [%.*s] %d %d %d %d %d\n", path, pos, path, n,
          //        &s[i + 1], n, depth, ed, ci, ei);
          //  NOTE(cpq): in the check sequence below is important.
          //  strncmp() must go first: it fails fast if the remaining length
          //  of the path is smaller than `n`.
          if (depth == ed && path[pos - 1] == '.' &&
              strncmp(&s[i + 1], &path[pos], (size_t) n) == 0 &&
              (path[pos + n] == '\0' || path[pos + n] == '.' ||
               path[pos + n] == '[')) {
            pos += n;
          }
          i += n + 1;
          expecting = S_COLON;
        } else if (c == '}') {  // Empty object
          MG_EOO('}');
          expecting = S_COMMA_OR_EOO;
          if (depth == ed && ei >= 0) ci++;
        } else {
          return MG_JSON_INVALID;
        }
        break;

      case S_COLON:
        if (c == ':') {
          expecting = S_VALUE;
        } else {
          return MG_JSON_INVALID;
        }
        break;

      case S_COMMA_OR_EOO:
        if (depth <= 0) {
          return MG_JSON_INVALID;
        } else if (c == ',') {
          expecting = (nesting[depth - 1] == '{') ? S_KEY : S_VALUE;
        } else if (c == ']' || c == '}') {
          if (depth == ed && c == '}' && path[pos - 1] == '.')
            return MG_JSON_NOT_FOUND;
          if (depth == ed && c == ']' && path[pos - 1] == ',')
            return MG_JSON_NOT_FOUND;
          MG_EOO('O');
          if (depth == ed && ei >= 0) ci++;
        } else {
          return MG_JSON_INVALID;
        }
        break;
    }
  }
  return MG_JSON_NOT_FOUND;
}

struct mg_str mg_json_get_tok(struct mg_str json, const char *path) {
  int len = 0, ofs = mg_json_get(json, path, &len);
  return mg_str_n(ofs < 0 ? NULL : json.buf + ofs,
                  (size_t) (len < 0 ? 0 : len));
}

bool mg_json_get_num(struct mg_str json, const char *path, double *v) {
  int n, toklen, found = 0;
  if ((n = mg_json_get(json, path, &toklen)) >= 0 &&
      (json.buf[n] == '-' || (json.buf[n] >= '0' && json.buf[n] <= '9'))) {
    if (v != NULL) *v = mg_atod(json.buf + n, toklen, NULL);
    found = 1;
  }
  return found;
}

bool mg_json_get_bool(struct mg_str json, const char *path, bool *v) {
  int found = 0, off = mg_json_get(json, path, NULL);
  if (off >= 0 && (json.buf[off] == 't' || json.buf[off] == 'f')) {
    if (v != NULL) *v = json.buf[off] == 't';
    found = 1;
  }
  return found;
}

bool mg_json_unescape(struct mg_str s, char *to, size_t n) {
  size_t i, j;
  for (i = 0, j = 0; i < s.len && j < n; i++, j++) {
    if (s.buf[i] == '\\' && i + 5 < s.len && s.buf[i + 1] == 'u') {
      //  \uXXXX escape. We process simple one-byte chars \u00xx within ASCII
      //  range. More complex chars would require dragging in a UTF8 library,
      //  which is too much for us
      if (mg_str_to_num(mg_str_n(s.buf + i + 2, 4), 16, &to[j],
                        sizeof(uint8_t)) == false)
        return false;
      i += 5;
    } else if (s.buf[i] == '\\' && i + 1 < s.len) {
      char c = json_esc(s.buf[i + 1], 0);
      if (c == 0) return false;
      to[j] = c;
      i++;
    } else {
      to[j] = s.buf[i];
    }
  }
  if (j >= n) return false;
  if (n > 0) to[j] = '\0';
  return true;
}

char *mg_json_get_str(struct mg_str json, const char *path) {
  char *result = NULL;
  int len = 0, off = mg_json_get(json, path, &len);
  if (off >= 0 && len > 1 && json.buf[off] == '"') {
    if ((result = (char *) calloc(1, (size_t) len)) != NULL &&
        !mg_json_unescape(mg_str_n(json.buf + off + 1, (size_t) (len - 2)),
                          result, (size_t) len)) {
      free(result);
      result = NULL;
    }
  }
  return result;
}

char *mg_json_get_b64(struct mg_str json, const char *path, int *slen) {
  char *result = NULL;
  int len = 0, off = mg_json_get(json, path, &len);
  if (off >= 0 && json.buf[off] == '"' && len > 1 &&
      (result = (char *) calloc(1, (size_t) len)) != NULL) {
    size_t k = mg_base64_decode(json.buf + off + 1, (size_t) (len - 2), result,
                                (size_t) len);
    if (slen != NULL) *slen = (int) k;
  }
  return result;
}

char *mg_json_get_hex(struct mg_str json, const char *path, int *slen) {
  char *result = NULL;
  int len = 0, off = mg_json_get(json, path, &len);
  if (off >= 0 && json.buf[off] == '"' && len > 1 &&
      (result = (char *) calloc(1, (size_t) len / 2)) != NULL) {
    int i;
    for (i = 0; i < len - 2; i += 2) {
      mg_str_to_num(mg_str_n(json.buf + off + 1 + i, 2), 16, &result[i >> 1],
                    sizeof(uint8_t));
    }
    result[len / 2 - 1] = '\0';
    if (slen != NULL) *slen = len / 2 - 1;
  }
  return result;
}

long mg_json_get_long(struct mg_str json, const char *path, long dflt) {
  double dv;
  long result = dflt;
  if (mg_json_get_num(json, path, &dv)) result = (long) dv;
  return result;
}

#ifdef MG_ENABLE_LINES
#line 1 "src/log.c"
#endif





int mg_log_level = MG_LL_INFO;
static mg_pfn_t s_log_func = mg_pfn_stdout;
static void *s_log_func_param = NULL;

void mg_log_set_fn(mg_pfn_t fn, void *param) {
  s_log_func = fn;
  s_log_func_param = param;
}

static void logc(unsigned char c) {
  s_log_func((char) c, s_log_func_param);
}

static void logs(const char *buf, size_t len) {
  size_t i;
  for (i = 0; i < len; i++) logc(((unsigned char *) buf)[i]);
}

#if MG_ENABLE_CUSTOM_LOG
// Let user define their own mg_log_prefix() and mg_log()
#else
void mg_log_prefix(int level, const char *file, int line, const char *fname) {
  const char *p = strrchr(file, '/');
  char buf[41];
  size_t n;
  if (p == NULL) p = strrchr(file, '\\');
  n = mg_snprintf(buf, sizeof(buf), "%-6llx %d %s:%d:%s", mg_millis(), level,
                  p == NULL ? file : p + 1, line, fname);
  if (n > sizeof(buf) - 2) n = sizeof(buf) - 2;
  while (n < sizeof(buf)) buf[n++] = ' ';
  logs(buf, n - 1);
}

void mg_log(const char *fmt, ...) {
  va_list ap;
  va_start(ap, fmt);
  mg_vxprintf(s_log_func, s_log_func_param, fmt, &ap);
  va_end(ap);
  logs("\r\n", 2);
}
#endif

static unsigned char nibble(unsigned c) {
  return (unsigned char) (c < 10 ? c + '0' : c + 'W');
}

#define ISPRINT(x) ((x) >= ' ' && (x) <= '~')
void mg_hexdump(const void *buf, size_t len) {
  const unsigned char *p = (const unsigned char *) buf;
  unsigned char ascii[16], alen = 0;
  size_t i;
  for (i = 0; i < len; i++) {
    if ((i % 16) == 0) {
      // Print buffered ascii chars
      if (i > 0) logs("  ", 2), logs((char *) ascii, 16), logc('\n'), alen = 0;
      // Print hex address, then \t
      logc(nibble((i >> 12) & 15)), logc(nibble((i >> 8) & 15)),
          logc(nibble((i >> 4) & 15)), logc('0'), logs("   ", 3);
    }
    logc(nibble(p[i] >> 4)), logc(nibble(p[i] & 15));  // Two nibbles, e.g. c5
    logc(' ');                                         // Space after hex number
    ascii[alen++] = ISPRINT(p[i]) ? p[i] : '.';        // Add to the ascii buf
  }
  while (alen < 16) logs("   ", 3), ascii[alen++] = ' ';
  logs("  ", 2), logs((char *) ascii, 16), logc('\n');
}

#ifdef MG_ENABLE_LINES
#line 1 "src/md5.c"
#endif



//  This code implements the MD5 message-digest algorithm.
//  The algorithm is due to Ron Rivest.  This code was
//  written by Colin Plumb in 1993, no copyright is claimed.
//  This code is in the public domain; do with it what you wish.
//
//  Equivalent code is available from RSA Data Security, Inc.
//  This code has been tested against that, and is equivalent,
//  except that you don't need to include two pages of legalese
//  with every copy.
//
//  To compute the message digest of a chunk of bytes, declare an
//  MD5Context structure, pass it to MD5Init, call MD5Update as
//  needed on buffers full of bytes, and then call MD5Final, which
//  will fill a supplied 16-byte array with the digest.

#if defined(MG_ENABLE_MD5) && MG_ENABLE_MD5

static void mg_byte_reverse(unsigned char *buf, unsigned longs) {
  if (MG_BIG_ENDIAN) {
    do {
      uint32_t t = (uint32_t) ((unsigned) buf[3] << 8 | buf[2]) << 16 |
                   ((unsigned) buf[1] << 8 | buf[0]);
      *(uint32_t *) buf = t;
      buf += 4;
    } while (--longs);
  } else {
    (void) buf, (void) longs;  // Little endian. Do nothing
  }
}

#define F1(x, y, z) (z ^ (x & (y ^ z)))
#define F2(x, y, z) F1(z, x, y)
#define F3(x, y, z) (x ^ y ^ z)
#define F4(x, y, z) (y ^ (x | ~z))

#define MD5STEP(f, w, x, y, z, data, s) \
  (w += f(x, y, z) + data, w = w << s | w >> (32 - s), w += x)

/*
 * Start MD5 accumulation.  Set bit count to 0 and buffer to mysterious
 * initialization constants.
 */
void mg_md5_init(mg_md5_ctx *ctx) {
  ctx->buf[0] = 0x67452301;
  ctx->buf[1] = 0xefcdab89;
  ctx->buf[2] = 0x98badcfe;
  ctx->buf[3] = 0x10325476;

  ctx->bits[0] = 0;
  ctx->bits[1] = 0;
}

static void mg_md5_transform(uint32_t buf[4], uint32_t const in[16]) {
  uint32_t a, b, c, d;

  a = buf[0];
  b = buf[1];
  c = buf[2];
  d = buf[3];

  MD5STEP(F1, a, b, c, d, in[0] + 0xd76aa478, 7);
  MD5STEP(F1, d, a, b, c, in[1] + 0xe8c7b756, 12);
  MD5STEP(F1, c, d, a, b, in[2] + 0x242070db, 17);
  MD5STEP(F1, b, c, d, a, in[3] + 0xc1bdceee, 22);
  MD5STEP(F1, a, b, c, d, in[4] + 0xf57c0faf, 7);
  MD5STEP(F1, d, a, b, c, in[5] + 0x4787c62a, 12);
  MD5STEP(F1, c, d, a, b, in[6] + 0xa8304613, 17);
  MD5STEP(F1, b, c, d, a, in[7] + 0xfd469501, 22);
  MD5STEP(F1, a, b, c, d, in[8] + 0x698098d8, 7);
  MD5STEP(F1, d, a, b, c, in[9] + 0x8b44f7af, 12);
  MD5STEP(F1, c, d, a, b, in[10] + 0xffff5bb1, 17);
  MD5STEP(F1, b, c, d, a, in[11] + 0x895cd7be, 22);
  MD5STEP(F1, a, b, c, d, in[12] + 0x6b901122, 7);
  MD5STEP(F1, d, a, b, c, in[13] + 0xfd987193, 12);
  MD5STEP(F1, c, d, a, b, in[14] + 0xa679438e, 17);
  MD5STEP(F1, b, c, d, a, in[15] + 0x49b40821, 22);

  MD5STEP(F2, a, b, c, d, in[1] + 0xf61e2562, 5);
  MD5STEP(F2, d, a, b, c, in[6] + 0xc040b340, 9);
  MD5STEP(F2, c, d, a, b, in[11] + 0x265e5a51, 14);
  MD5STEP(F2, b, c, d, a, in[0] + 0xe9b6c7aa, 20);
  MD5STEP(F2, a, b, c, d, in[5] + 0xd62f105d, 5);
  MD5STEP(F2, d, a, b, c, in[10] + 0x02441453, 9);
  MD5STEP(F2, c, d, a, b, in[15] + 0xd8a1e681, 14);
  MD5STEP(F2, b, c, d, a, in[4] + 0xe7d3fbc8, 20);
  MD5STEP(F2, a, b, c, d, in[9] + 0x21e1cde6, 5);
  MD5STEP(F2, d, a, b, c, in[14] + 0xc33707d6, 9);
  MD5STEP(F2, c, d, a, b, in[3] + 0xf4d50d87, 14);
  MD5STEP(F2, b, c, d, a, in[8] + 0x455a14ed, 20);
  MD5STEP(F2, a, b, c, d, in[13] + 0xa9e3e905, 5);
  MD5STEP(F2, d, a, b, c, in[2] + 0xfcefa3f8, 9);
  MD5STEP(F2, c, d, a, b, in[7] + 0x676f02d9, 14);
  MD5STEP(F2, b, c, d, a, in[12] + 0x8d2a4c8a, 20);

  MD5STEP(F3, a, b, c, d, in[5] + 0xfffa3942, 4);
  MD5STEP(F3, d, a, b, c, in[8] + 0x8771f681, 11);
  MD5STEP(F3, c, d, a, b, in[11] + 0x6d9d6122, 16);
  MD5STEP(F3, b, c, d, a, in[14] + 0xfde5380c, 23);
  MD5STEP(F3, a, b, c, d, in[1] + 0xa4beea44, 4);
  MD5STEP(F3, d, a, b, c, in[4] + 0x4bdecfa9, 11);
  MD5STEP(F3, c, d, a, b, in[7] + 0xf6bb4b60, 16);
  MD5STEP(F3, b, c, d, a, in[10] + 0xbebfbc70, 23);
  MD5STEP(F3, a, b, c, d, in[13] + 0x289b7ec6, 4);
  MD5STEP(F3, d, a, b, c, in[0] + 0xeaa127fa, 11);
  MD5STEP(F3, c, d, a, b, in[3] + 0xd4ef3085, 16);
  MD5STEP(F3, b, c, d, a, in[6] + 0x04881d05, 23);
  MD5STEP(F3, a, b, c, d, in[9] + 0xd9d4d039, 4);
  MD5STEP(F3, d, a, b, c, in[12] + 0xe6db99e5, 11);
  MD5STEP(F3, c, d, a, b, in[15] + 0x1fa27cf8, 16);
  MD5STEP(F3, b, c, d, a, in[2] + 0xc4ac5665, 23);

  MD5STEP(F4, a, b, c, d, in[0] + 0xf4292244, 6);
  MD5STEP(F4, d, a, b, c, in[7] + 0x432aff97, 10);
  MD5STEP(F4, c, d, a, b, in[14] + 0xab9423a7, 15);
  MD5STEP(F4, b, c, d, a, in[5] + 0xfc93a039, 21);
  MD5STEP(F4, a, b, c, d, in[12] + 0x655b59c3, 6);
  MD5STEP(F4, d, a, b, c, in[3] + 0x8f0ccc92, 10);
  MD5STEP(F4, c, d, a, b, in[10] + 0xffeff47d, 15);
  MD5STEP(F4, b, c, d, a, in[1] + 0x85845dd1, 21);
  MD5STEP(F4, a, b, c, d, in[8] + 0x6fa87e4f, 6);
  MD5STEP(F4, d, a, b, c, in[15] + 0xfe2ce6e0, 10);
  MD5STEP(F4, c, d, a, b, in[6] + 0xa3014314, 15);
  MD5STEP(F4, b, c, d, a, in[13] + 0x4e0811a1, 21);
  MD5STEP(F4, a, b, c, d, in[4] + 0xf7537e82, 6);
  MD5STEP(F4, d, a, b, c, in[11] + 0xbd3af235, 10);
  MD5STEP(F4, c, d, a, b, in[2] + 0x2ad7d2bb, 15);
  MD5STEP(F4, b, c, d, a, in[9] + 0xeb86d391, 21);

  buf[0] += a;
  buf[1] += b;
  buf[2] += c;
  buf[3] += d;
}

void mg_md5_update(mg_md5_ctx *ctx, const unsigned char *buf, size_t len) {
  uint32_t t;

  t = ctx->bits[0];
  if ((ctx->bits[0] = t + ((uint32_t) len << 3)) < t) ctx->bits[1]++;
  ctx->bits[1] += (uint32_t) len >> 29;

  t = (t >> 3) & 0x3f;

  if (t) {
    unsigned char *p = (unsigned char *) ctx->in + t;

    t = 64 - t;
    if (len < t) {
      memcpy(p, buf, len);
      return;
    }
    memcpy(p, buf, t);
    mg_byte_reverse(ctx->in, 16);
    mg_md5_transform(ctx->buf, (uint32_t *) ctx->in);
    buf += t;
    len -= t;
  }

  while (len >= 64) {
    memcpy(ctx->in, buf, 64);
    mg_byte_reverse(ctx->in, 16);
    mg_md5_transform(ctx->buf, (uint32_t *) ctx->in);
    buf += 64;
    len -= 64;
  }

  memcpy(ctx->in, buf, len);
}

void mg_md5_final(mg_md5_ctx *ctx, unsigned char digest[16]) {
  unsigned count;
  unsigned char *p;
  uint32_t *a;

  count = (ctx->bits[0] >> 3) & 0x3F;

  p = ctx->in + count;
  *p++ = 0x80;
  count = 64 - 1 - count;
  if (count < 8) {
    memset(p, 0, count);
    mg_byte_reverse(ctx->in, 16);
    mg_md5_transform(ctx->buf, (uint32_t *) ctx->in);
    memset(ctx->in, 0, 56);
  } else {
    memset(p, 0, count - 8);
  }
  mg_byte_reverse(ctx->in, 14);

  a = (uint32_t *) ctx->in;
  a[14] = ctx->bits[0];
  a[15] = ctx->bits[1];

  mg_md5_transform(ctx->buf, (uint32_t *) ctx->in);
  mg_byte_reverse((unsigned char *) ctx->buf, 4);
  memcpy(digest, ctx->buf, 16);
  memset((char *) ctx, 0, sizeof(*ctx));
}
#endif

#ifdef MG_ENABLE_LINES
#line 1 "src/mqtt.c"
#endif








#define MQTT_CLEAN_SESSION 0x02
#define MQTT_HAS_WILL 0x04
#define MQTT_WILL_RETAIN 0x20
#define MQTT_HAS_PASSWORD 0x40
#define MQTT_HAS_USER_NAME 0x80

struct mg_mqtt_pmap {
  uint8_t id;
  uint8_t type;
};

static const struct mg_mqtt_pmap s_prop_map[] = {
    {MQTT_PROP_PAYLOAD_FORMAT_INDICATOR, MQTT_PROP_TYPE_BYTE},
    {MQTT_PROP_MESSAGE_EXPIRY_INTERVAL, MQTT_PROP_TYPE_INT},
    {MQTT_PROP_CONTENT_TYPE, MQTT_PROP_TYPE_STRING},
    {MQTT_PROP_RESPONSE_TOPIC, MQTT_PROP_TYPE_STRING},
    {MQTT_PROP_CORRELATION_DATA, MQTT_PROP_TYPE_BINARY_DATA},
    {MQTT_PROP_SUBSCRIPTION_IDENTIFIER, MQTT_PROP_TYPE_VARIABLE_INT},
    {MQTT_PROP_SESSION_EXPIRY_INTERVAL, MQTT_PROP_TYPE_INT},
    {MQTT_PROP_ASSIGNED_CLIENT_IDENTIFIER, MQTT_PROP_TYPE_STRING},
    {MQTT_PROP_SERVER_KEEP_ALIVE, MQTT_PROP_TYPE_SHORT},
    {MQTT_PROP_AUTHENTICATION_METHOD, MQTT_PROP_TYPE_STRING},
    {MQTT_PROP_AUTHENTICATION_DATA, MQTT_PROP_TYPE_BINARY_DATA},
    {MQTT_PROP_REQUEST_PROBLEM_INFORMATION, MQTT_PROP_TYPE_BYTE},
    {MQTT_PROP_WILL_DELAY_INTERVAL, MQTT_PROP_TYPE_INT},
    {MQTT_PROP_REQUEST_RESPONSE_INFORMATION, MQTT_PROP_TYPE_BYTE},
    {MQTT_PROP_RESPONSE_INFORMATION, MQTT_PROP_TYPE_STRING},
    {MQTT_PROP_SERVER_REFERENCE, MQTT_PROP_TYPE_STRING},
    {MQTT_PROP_REASON_STRING, MQTT_PROP_TYPE_STRING},
    {MQTT_PROP_RECEIVE_MAXIMUM, MQTT_PROP_TYPE_SHORT},
    {MQTT_PROP_TOPIC_ALIAS_MAXIMUM, MQTT_PROP_TYPE_SHORT},
    {MQTT_PROP_TOPIC_ALIAS, MQTT_PROP_TYPE_SHORT},
    {MQTT_PROP_MAXIMUM_QOS, MQTT_PROP_TYPE_BYTE},
    {MQTT_PROP_RETAIN_AVAILABLE, MQTT_PROP_TYPE_BYTE},
    {MQTT_PROP_USER_PROPERTY, MQTT_PROP_TYPE_STRING_PAIR},
    {MQTT_PROP_MAXIMUM_PACKET_SIZE, MQTT_PROP_TYPE_INT},
    {MQTT_PROP_WILDCARD_SUBSCRIPTION_AVAILABLE, MQTT_PROP_TYPE_BYTE},
    {MQTT_PROP_SUBSCRIPTION_IDENTIFIER_AVAILABLE, MQTT_PROP_TYPE_BYTE},
    {MQTT_PROP_SHARED_SUBSCRIPTION_AVAILABLE, MQTT_PROP_TYPE_BYTE}};

void mg_mqtt_send_header(struct mg_connection *c, uint8_t cmd, uint8_t flags,
                         uint32_t len) {
  uint8_t buf[1 + sizeof(len)], *vlen = &buf[1];
  buf[0] = (uint8_t) ((cmd << 4) | flags);
  do {
    *vlen = len % 0x80;
    len /= 0x80;
    if (len > 0) *vlen |= 0x80;
    vlen++;
  } while (len > 0 && vlen < &buf[sizeof(buf)]);
  mg_send(c, buf, (size_t) (vlen - buf));
}

static void mg_send_u16(struct mg_connection *c, uint16_t value) {
  mg_send(c, &value, sizeof(value));
}

static void mg_send_u32(struct mg_connection *c, uint32_t value) {
  mg_send(c, &value, sizeof(value));
}

static uint8_t varint_size(size_t length) {
  uint8_t bytes_needed = 0;
  do {
    bytes_needed++;
    length /= 0x80;
  } while (length > 0);
  return bytes_needed;
}

static size_t encode_varint(uint8_t *buf, size_t value) {
  size_t len = 0;

  do {
    uint8_t b = (uint8_t) (value % 128);
    value /= 128;
    if (value > 0) b |= 0x80;
    buf[len++] = b;
  } while (value > 0);

  return len;
}

static size_t decode_varint(const uint8_t *buf, size_t len, size_t *value) {
  size_t multiplier = 1, offset;
  *value = 0;

  for (offset = 0; offset < 4 && offset < len; offset++) {
    uint8_t encoded_byte = buf[offset];
    *value += (encoded_byte & 0x7f) * multiplier;
    multiplier *= 128;

    if ((encoded_byte & 0x80) == 0) return offset + 1;
  }

  return 0;
}

static int mqtt_prop_type_by_id(uint8_t prop_id) {
  size_t i, num_properties = sizeof(s_prop_map) / sizeof(s_prop_map[0]);
  for (i = 0; i < num_properties; ++i) {
    if (s_prop_map[i].id == prop_id) return s_prop_map[i].type;
  }
  return -1;  // Property ID not found
}

// Returns the size of the properties section, without the
// size of the content's length
static size_t get_properties_length(struct mg_mqtt_prop *props, size_t count) {
  size_t i, size = 0;
  for (i = 0; i < count; i++) {
    size++;  // identifier
    switch (mqtt_prop_type_by_id(props[i].id)) {
      case MQTT_PROP_TYPE_STRING_PAIR:
        size += (uint32_t) (props[i].val.len + props[i].key.len +
                            2 * sizeof(uint16_t));
        break;
      case MQTT_PROP_TYPE_STRING:
        size += (uint32_t) (props[i].val.len + sizeof(uint16_t));
        break;
      case MQTT_PROP_TYPE_BINARY_DATA:
        size += (uint32_t) (props[i].val.len + sizeof(uint16_t));
        break;
      case MQTT_PROP_TYPE_VARIABLE_INT:
        size += varint_size((uint32_t) props[i].iv);
        break;
      case MQTT_PROP_TYPE_INT:
        size += (uint32_t) sizeof(uint32_t);
        break;
      case MQTT_PROP_TYPE_SHORT:
        size += (uint32_t) sizeof(uint16_t);
        break;
      case MQTT_PROP_TYPE_BYTE:
        size += (uint32_t) sizeof(uint8_t);
        break;
      default:
        return size;  // cannot parse further down
    }
  }

  return size;
}

// returns the entire size of the properties section, including the
// size of the variable length of the content
static size_t get_props_size(struct mg_mqtt_prop *props, size_t count) {
  size_t size = get_properties_length(props, count);
  size += varint_size(size);
  return size;
}

static void mg_send_mqtt_properties(struct mg_connection *c,
                                    struct mg_mqtt_prop *props, size_t nprops) {
  size_t total_size = get_properties_length(props, nprops);
  uint8_t buf_v[4] = {0, 0, 0, 0};
  uint8_t buf[4] = {0, 0, 0, 0};
  size_t i, len = encode_varint(buf, total_size);

  mg_send(c, buf, (size_t) len);
  for (i = 0; i < nprops; i++) {
    mg_send(c, &props[i].id, sizeof(props[i].id));
    switch (mqtt_prop_type_by_id(props[i].id)) {
      case MQTT_PROP_TYPE_STRING_PAIR:
        mg_send_u16(c, mg_htons((uint16_t) props[i].key.len));
        mg_send(c, props[i].key.buf, props[i].key.len);
        mg_send_u16(c, mg_htons((uint16_t) props[i].val.len));
        mg_send(c, props[i].val.buf, props[i].val.len);
        break;
      case MQTT_PROP_TYPE_BYTE:
        mg_send(c, &props[i].iv, sizeof(uint8_t));
        break;
      case MQTT_PROP_TYPE_SHORT:
        mg_send_u16(c, mg_htons((uint16_t) props[i].iv));
        break;
      case MQTT_PROP_TYPE_INT:
        mg_send_u32(c, mg_htonl((uint32_t) props[i].iv));
        break;
      case MQTT_PROP_TYPE_STRING:
        mg_send_u16(c, mg_htons((uint16_t) props[i].val.len));
        mg_send(c, props[i].val.buf, props[i].val.len);
        break;
      case MQTT_PROP_TYPE_BINARY_DATA:
        mg_send_u16(c, mg_htons((uint16_t) props[i].val.len));
        mg_send(c, props[i].val.buf, props[i].val.len);
        break;
      case MQTT_PROP_TYPE_VARIABLE_INT:
        len = encode_varint(buf_v, props[i].iv);
        mg_send(c, buf_v, (size_t) len);
        break;
    }
  }
}

size_t mg_mqtt_next_prop(struct mg_mqtt_message *msg, struct mg_mqtt_prop *prop,
                         size_t ofs) {
  uint8_t *i = (uint8_t *) msg->dgram.buf + msg->props_start + ofs;
  uint8_t *end = (uint8_t *) msg->dgram.buf + msg->dgram.len;
  size_t new_pos = ofs, len;
  prop->id = i[0];

  if (ofs >= msg->dgram.len || ofs >= msg->props_start + msg->props_size)
    return 0;
  i++, new_pos++;

  switch (mqtt_prop_type_by_id(prop->id)) {
    case MQTT_PROP_TYPE_STRING_PAIR:
      prop->key.len = (uint16_t) ((((uint16_t) i[0]) << 8) | i[1]);
      prop->key.buf = (char *) i + 2;
      i += 2 + prop->key.len;
      prop->val.len = (uint16_t) ((((uint16_t) i[0]) << 8) | i[1]);
      prop->val.buf = (char *) i + 2;
      new_pos += 2 * sizeof(uint16_t) + prop->val.len + prop->key.len;
      break;
    case MQTT_PROP_TYPE_BYTE:
      prop->iv = (uint8_t) i[0];
      new_pos++;
      break;
    case MQTT_PROP_TYPE_SHORT:
      prop->iv = (uint16_t) ((((uint16_t) i[0]) << 8) | i[1]);
      new_pos += sizeof(uint16_t);
      break;
    case MQTT_PROP_TYPE_INT:
      prop->iv = ((uint32_t) i[0] << 24) | ((uint32_t) i[1] << 16) |
                 ((uint32_t) i[2] << 8) | i[3];
      new_pos += sizeof(uint32_t);
      break;
    case MQTT_PROP_TYPE_STRING:
      prop->val.len = (uint16_t) ((((uint16_t) i[0]) << 8) | i[1]);
      prop->val.buf = (char *) i + 2;
      new_pos += 2 + prop->val.len;
      break;
    case MQTT_PROP_TYPE_BINARY_DATA:
      prop->val.len = (uint16_t) ((((uint16_t) i[0]) << 8) | i[1]);
      prop->val.buf = (char *) i + 2;
      new_pos += 2 + prop->val.len;
      break;
    case MQTT_PROP_TYPE_VARIABLE_INT:
      len = decode_varint(i, (size_t) (end - i), (size_t *) &prop->iv);
      new_pos = (!len) ? 0 : new_pos + len;
      break;
    default:
      new_pos = 0;
  }

  return new_pos;
}

void mg_mqtt_login(struct mg_connection *c, const struct mg_mqtt_opts *opts) {
  char client_id[21];
  struct mg_str cid = opts->client_id;
  size_t total_len = 7 + 1 + 2 + 2;
  uint8_t hdr[8] = {0, 4, 'M', 'Q', 'T', 'T', opts->version, 0};

  if (cid.len == 0) {
    mg_random_str(client_id, sizeof(client_id) - 1);
    client_id[sizeof(client_id) - 1] = '\0';
    cid = mg_str(client_id);
  }

  if (hdr[6] == 0) hdr[6] = 4;  // If version is not set, use 4 (3.1.1)
  c->is_mqtt5 = hdr[6] == 5;    // Set version 5 flag
  hdr[7] = (uint8_t) ((opts->qos & 3) << 3);  // Connection flags
  if (opts->user.len > 0) {
    total_len += 2 + (uint32_t) opts->user.len;
    hdr[7] |= MQTT_HAS_USER_NAME;
  }
  if (opts->pass.len > 0) {
    total_len += 2 + (uint32_t) opts->pass.len;
    hdr[7] |= MQTT_HAS_PASSWORD;
  }
  if (opts->topic.len > 0) {  // allow zero-length msgs, message.len is size_t
    total_len += 4 + (uint32_t) opts->topic.len + (uint32_t) opts->message.len;
    hdr[7] |= MQTT_HAS_WILL;
  }
  if (opts->clean || cid.len == 0) hdr[7] |= MQTT_CLEAN_SESSION;
  if (opts->retain) hdr[7] |= MQTT_WILL_RETAIN;
  total_len += (uint32_t) cid.len;
  if (c->is_mqtt5) {
    total_len += get_props_size(opts->props, opts->num_props);
    if (hdr[7] & MQTT_HAS_WILL)
      total_len += get_props_size(opts->will_props, opts->num_will_props);
  }

  mg_mqtt_send_header(c, MQTT_CMD_CONNECT, 0, (uint32_t) total_len);
  mg_send(c, hdr, sizeof(hdr));
  // keepalive == 0 means "do not disconnect us!"
  mg_send_u16(c, mg_htons((uint16_t) opts->keepalive));

  if (c->is_mqtt5) mg_send_mqtt_properties(c, opts->props, opts->num_props);

  mg_send_u16(c, mg_htons((uint16_t) cid.len));
  mg_send(c, cid.buf, cid.len);

  if (hdr[7] & MQTT_HAS_WILL) {
    if (c->is_mqtt5)
      mg_send_mqtt_properties(c, opts->will_props, opts->num_will_props);

    mg_send_u16(c, mg_htons((uint16_t) opts->topic.len));
    mg_send(c, opts->topic.buf, opts->topic.len);
    mg_send_u16(c, mg_htons((uint16_t) opts->message.len));
    mg_send(c, opts->message.buf, opts->message.len);
  }
  if (opts->user.len > 0) {
    mg_send_u16(c, mg_htons((uint16_t) opts->user.len));
    mg_send(c, opts->user.buf, opts->user.len);
  }
  if (opts->pass.len > 0) {
    mg_send_u16(c, mg_htons((uint16_t) opts->pass.len));
    mg_send(c, opts->pass.buf, opts->pass.len);
  }
}

uint16_t mg_mqtt_pub(struct mg_connection *c, const struct mg_mqtt_opts *opts) {
  uint16_t id = opts->retransmit_id;
  uint8_t flags = (uint8_t) (((opts->qos & 3) << 1) | (opts->retain ? 1 : 0));
  size_t len = 2 + opts->topic.len + opts->message.len;
  MG_DEBUG(("%lu [%.*s] <- [%.*s%c", c->id, (int) opts->topic.len,
            (char *) opts->topic.buf,
            (int) (opts->message.len <= 10 ? opts->message.len : 10),
            (char *) opts->message.buf, opts->message.len <= 10 ? ']' : ' '));
  if (opts->qos > 0) len += 2;
  if (c->is_mqtt5) len += get_props_size(opts->props, opts->num_props);

  if (opts->qos > 0 && id != 0) flags |= 1 << 3;
  mg_mqtt_send_header(c, MQTT_CMD_PUBLISH, flags, (uint32_t) len);
  mg_send_u16(c, mg_htons((uint16_t) opts->topic.len));
  mg_send(c, opts->topic.buf, opts->topic.len);
  if (opts->qos > 0) {  // need to send 'id' field
    if (id == 0) {      // generate new one if not resending
      if (++c->mgr->mqtt_id == 0) ++c->mgr->mqtt_id;
      id = c->mgr->mqtt_id;
    }
    mg_send_u16(c, mg_htons(id));
  }

  if (c->is_mqtt5) mg_send_mqtt_properties(c, opts->props, opts->num_props);

  if (opts->message.len > 0) mg_send(c, opts->message.buf, opts->message.len);
  return id;
}

void mg_mqtt_sub(struct mg_connection *c, const struct mg_mqtt_opts *opts) {
  uint8_t qos_ = opts->qos & 3;
  size_t plen = c->is_mqtt5 ? get_props_size(opts->props, opts->num_props) : 0;
  size_t len = 2 + opts->topic.len + 2 + 1 + plen;

  mg_mqtt_send_header(c, MQTT_CMD_SUBSCRIBE, 2, (uint32_t) len);
  if (++c->mgr->mqtt_id == 0) ++c->mgr->mqtt_id;
  mg_send_u16(c, mg_htons(c->mgr->mqtt_id));
  if (c->is_mqtt5) mg_send_mqtt_properties(c, opts->props, opts->num_props);

  mg_send_u16(c, mg_htons((uint16_t) opts->topic.len));
  mg_send(c, opts->topic.buf, opts->topic.len);
  mg_send(c, &qos_, sizeof(qos_));
}

int mg_mqtt_parse(const uint8_t *buf, size_t len, uint8_t version,
                  struct mg_mqtt_message *m) {
  uint8_t lc = 0, *p, *end;
  uint32_t n = 0, len_len = 0;

  memset(m, 0, sizeof(*m));
  m->dgram.buf = (char *) buf;
  if (len < 2) return MQTT_INCOMPLETE;
  m->cmd = (uint8_t) (buf[0] >> 4);
  m->qos = (buf[0] >> 1) & 3;

  n = len_len = 0;
  p = (uint8_t *) buf + 1;
  while ((size_t) (p - buf) < len) {
    lc = *((uint8_t *) p++);
    n += (uint32_t) ((lc & 0x7f) << 7 * len_len);
    len_len++;
    if (!(lc & 0x80)) break;
    if (len_len >= 4) return MQTT_MALFORMED;
  }
  end = p + n;
  if ((lc & 0x80) || (end > buf + len)) return MQTT_INCOMPLETE;
  m->dgram.len = (size_t) (end - buf);

  switch (m->cmd) {
    case MQTT_CMD_CONNACK:
      if (end - p < 2) return MQTT_MALFORMED;
      m->ack = p[1];
      break;
    case MQTT_CMD_PUBACK:
    case MQTT_CMD_PUBREC:
    case MQTT_CMD_PUBREL:
    case MQTT_CMD_PUBCOMP:
    case MQTT_CMD_SUBSCRIBE:
    case MQTT_CMD_SUBACK:
    case MQTT_CMD_UNSUBSCRIBE:
    case MQTT_CMD_UNSUBACK:
      if (p + 2 > end) return MQTT_MALFORMED;
      m->id = (uint16_t) ((((uint16_t) p[0]) << 8) | p[1]);
      p += 2;
      break;
    case MQTT_CMD_PUBLISH: {
      if (p + 2 > end) return MQTT_MALFORMED;
      m->topic.len = (uint16_t) ((((uint16_t) p[0]) << 8) | p[1]);
      m->topic.buf = (char *) p + 2;
      p += 2 + m->topic.len;
      if (p > end) return MQTT_MALFORMED;
      if (m->qos > 0) {
        if (p + 2 > end) return MQTT_MALFORMED;
        m->id = (uint16_t) ((((uint16_t) p[0]) << 8) | p[1]);
        p += 2;
      }
      if (p > end) return MQTT_MALFORMED;
      if (version == 5 && p + 2 < end) {
        len_len =
            (uint32_t) decode_varint(p, (size_t) (end - p), &m->props_size);
        if (!len_len) return MQTT_MALFORMED;
        m->props_start = (size_t) (p + len_len - buf);
        p += len_len + m->props_size;
      }
      if (p > end) return MQTT_MALFORMED;
      m->data.buf = (char *) p;
      m->data.len = (size_t) (end - p);
      break;
    }
    default:
      break;
  }
  return MQTT_OK;
}

static void mqtt_cb(struct mg_connection *c, int ev, void *ev_data) {
  if (ev == MG_EV_READ) {
    for (;;) {
      uint8_t version = c->is_mqtt5 ? 5 : 4;
      struct mg_mqtt_message mm;
      int rc = mg_mqtt_parse(c->recv.buf, c->recv.len, version, &mm);
      if (rc == MQTT_MALFORMED) {
        MG_ERROR(("%lu MQTT malformed message", c->id));
        c->is_closing = 1;
        break;
      } else if (rc == MQTT_OK) {
        MG_VERBOSE(("%lu MQTT CMD %d len %d [%.*s]", c->id, mm.cmd,
                    (int) mm.dgram.len, (int) mm.data.len, mm.data.buf));
        switch (mm.cmd) {
          case MQTT_CMD_CONNACK:
            mg_call(c, MG_EV_MQTT_OPEN, &mm.ack);
            if (mm.ack == 0) {
              MG_DEBUG(("%lu Connected", c->id));
            } else {
              MG_ERROR(("%lu MQTT auth failed, code %d", c->id, mm.ack));
              c->is_closing = 1;
            }
            break;
          case MQTT_CMD_PUBLISH: {
            MG_DEBUG(("%lu [%.*s] -> [%.*s%c", c->id, (int) mm.topic.len,
                      mm.topic.buf,
                      (int) (mm.data.len <= 10 ? mm.data.len : 10), mm.data.buf,
                      mm.data.len <= 10 ? ']' : ' '));
            if (mm.qos > 0) {
              uint16_t id = mg_ntohs(mm.id);
              uint32_t remaining_len = sizeof(id);
              if (c->is_mqtt5) remaining_len += 2;  // 3.4.2

              mg_mqtt_send_header(
                  c,
                  (uint8_t) (mm.qos == 2 ? MQTT_CMD_PUBREC : MQTT_CMD_PUBACK),
                  0, remaining_len);
              mg_send(c, &id, sizeof(id));

              if (c->is_mqtt5) {
                uint16_t zero = 0;
                mg_send(c, &zero, sizeof(zero));
              }
            }
            mg_call(c, MG_EV_MQTT_MSG, &mm);  // let the app handle qos stuff
            break;
          }
          case MQTT_CMD_PUBREC: {  // MQTT5: 3.5.2-1 TODO(): variable header rc
            uint16_t id = mg_ntohs(mm.id);
            uint32_t remaining_len = sizeof(id);  // MQTT5 3.6.2-1
            mg_mqtt_send_header(c, MQTT_CMD_PUBREL, 2, remaining_len);
            mg_send(c, &id, sizeof(id));  // MQTT5 3.6.1-1, flags = 2
            break;
          }
          case MQTT_CMD_PUBREL: {  // MQTT5: 3.6.2-1 TODO(): variable header rc
            uint16_t id = mg_ntohs(mm.id);
            uint32_t remaining_len = sizeof(id);  // MQTT5 3.7.2-1
            mg_mqtt_send_header(c, MQTT_CMD_PUBCOMP, 0, remaining_len);
            mg_send(c, &id, sizeof(id));
            break;
          }
        }
        mg_call(c, MG_EV_MQTT_CMD, &mm);
        mg_iobuf_del(&c->recv, 0, mm.dgram.len);
      } else {
        break;
      }
    }
  }
  (void) ev_data;
}

void mg_mqtt_ping(struct mg_connection *nc) {
  mg_mqtt_send_header(nc, MQTT_CMD_PINGREQ, 0, 0);
}

void mg_mqtt_pong(struct mg_connection *nc) {
  mg_mqtt_send_header(nc, MQTT_CMD_PINGRESP, 0, 0);
}

void mg_mqtt_disconnect(struct mg_connection *c,
                        const struct mg_mqtt_opts *opts) {
  size_t len = 0;
  if (c->is_mqtt5) len = 1 + get_props_size(opts->props, opts->num_props);
  mg_mqtt_send_header(c, MQTT_CMD_DISCONNECT, 0, (uint32_t) len);

  if (c->is_mqtt5) {
    uint8_t zero = 0;
    mg_send(c, &zero, sizeof(zero));  // reason code
    mg_send_mqtt_properties(c, opts->props, opts->num_props);
  }
}

struct mg_connection *mg_mqtt_connect(struct mg_mgr *mgr, const char *url,
                                      const struct mg_mqtt_opts *opts,
                                      mg_event_handler_t fn, void *fn_data) {
  struct mg_connection *c = mg_connect(mgr, url, fn, fn_data);
  if (c != NULL) {
    struct mg_mqtt_opts empty;
    memset(&empty, 0, sizeof(empty));
    mg_mqtt_login(c, opts == NULL ? &empty : opts);
    c->pfn = mqtt_cb;
  }
  return c;
}

struct mg_connection *mg_mqtt_listen(struct mg_mgr *mgr, const char *url,
                                     mg_event_handler_t fn, void *fn_data) {
  struct mg_connection *c = mg_listen(mgr, url, fn, fn_data);
  if (c != NULL) c->pfn = mqtt_cb, c->pfn_data = mgr;
  return c;
}

#ifdef MG_ENABLE_LINES
#line 1 "src/net.c"
#endif









size_t mg_vprintf(struct mg_connection *c, const char *fmt, va_list *ap) {
  size_t old = c->send.len;
  mg_vxprintf(mg_pfn_iobuf, &c->send, fmt, ap);
  return c->send.len - old;
}

size_t mg_printf(struct mg_connection *c, const char *fmt, ...) {
  size_t len = 0;
  va_list ap;
  va_start(ap, fmt);
  len = mg_vprintf(c, fmt, &ap);
  va_end(ap);
  return len;
}

static bool mg_atonl(struct mg_str str, struct mg_addr *addr) {
  uint32_t localhost = mg_htonl(0x7f000001);
  if (mg_strcasecmp(str, mg_str("localhost")) != 0) return false;
  memcpy(addr->ip, &localhost, sizeof(uint32_t));
  addr->is_ip6 = false;
  return true;
}

static bool mg_atone(struct mg_str str, struct mg_addr *addr) {
  if (str.len > 0) return false;
  memset(addr->ip, 0, sizeof(addr->ip));
  addr->is_ip6 = false;
  return true;
}

static bool mg_aton4(struct mg_str str, struct mg_addr *addr) {
  uint8_t data[4] = {0, 0, 0, 0};
  size_t i, num_dots = 0;
  for (i = 0; i < str.len; i++) {
    if (str.buf[i] >= '0' && str.buf[i] <= '9') {
      int octet = data[num_dots] * 10 + (str.buf[i] - '0');
      if (octet > 255) return false;
      data[num_dots] = (uint8_t) octet;
    } else if (str.buf[i] == '.') {
      if (num_dots >= 3 || i == 0 || str.buf[i - 1] == '.') return false;
      num_dots++;
    } else {
      return false;
    }
  }
  if (num_dots != 3 || str.buf[i - 1] == '.') return false;
  memcpy(&addr->ip, data, sizeof(data));
  addr->is_ip6 = false;
  return true;
}

static bool mg_v4mapped(struct mg_str str, struct mg_addr *addr) {
  int i;
  uint32_t ipv4;
  if (str.len < 14) return false;
  if (str.buf[0] != ':' || str.buf[1] != ':' || str.buf[6] != ':') return false;
  for (i = 2; i < 6; i++) {
    if (str.buf[i] != 'f' && str.buf[i] != 'F') return false;
  }
  // struct mg_str s = mg_str_n(&str.buf[7], str.len - 7);
  if (!mg_aton4(mg_str_n(&str.buf[7], str.len - 7), addr)) return false;
  memcpy(&ipv4, addr->ip, sizeof(ipv4));
  memset(addr->ip, 0, sizeof(addr->ip));
  addr->ip[10] = addr->ip[11] = 255;
  memcpy(&addr->ip[12], &ipv4, 4);
  addr->is_ip6 = true;
  return true;
}

static bool mg_aton6(struct mg_str str, struct mg_addr *addr) {
  size_t i, j = 0, n = 0, dc = 42;
  addr->scope_id = 0;
  if (str.len > 2 && str.buf[0] == '[') str.buf++, str.len -= 2;
  if (mg_v4mapped(str, addr)) return true;
  for (i = 0; i < str.len; i++) {
    if ((str.buf[i] >= '0' && str.buf[i] <= '9') ||
        (str.buf[i] >= 'a' && str.buf[i] <= 'f') ||
        (str.buf[i] >= 'A' && str.buf[i] <= 'F')) {
      unsigned long val = 0;  // TODO(): This loops on chars, refactor
      if (i > j + 3) return false;
      // MG_DEBUG(("%lu %lu [%.*s]", i, j, (int) (i - j + 1), &str.buf[j]));
      mg_str_to_num(mg_str_n(&str.buf[j], i - j + 1), 16, &val, sizeof(val));
      addr->ip[n] = (uint8_t) ((val >> 8) & 255);
      addr->ip[n + 1] = (uint8_t) (val & 255);
    } else if (str.buf[i] == ':') {
      j = i + 1;
      if (i > 0 && str.buf[i - 1] == ':') {
        dc = n;  // Double colon
        if (i > 1 && str.buf[i - 2] == ':') return false;
      } else if (i > 0) {
        n += 2;
      }
      if (n > 14) return false;
      addr->ip[n] = addr->ip[n + 1] = 0;  // For trailing ::
    } else if (str.buf[i] == '%') {       // Scope ID, last in string
      return mg_str_to_num(mg_str_n(&str.buf[i + 1], str.len - i - 1), 10,
                           &addr->scope_id, sizeof(uint8_t));
    } else {
      return false;
    }
  }
  if (n < 14 && dc == 42) return false;
  if (n < 14) {
    memmove(&addr->ip[dc + (14 - n)], &addr->ip[dc], n - dc + 2);
    memset(&addr->ip[dc], 0, 14 - n);
  }

  addr->is_ip6 = true;
  return true;
}

bool mg_aton(struct mg_str str, struct mg_addr *addr) {
  // MG_INFO(("[%.*s]", (int) str.len, str.buf));
  return mg_atone(str, addr) || mg_atonl(str, addr) || mg_aton4(str, addr) ||
         mg_aton6(str, addr);
}

struct mg_connection *mg_alloc_conn(struct mg_mgr *mgr) {
  struct mg_connection *c =
      (struct mg_connection *) calloc(1, sizeof(*c) + mgr->extraconnsize);
  if (c != NULL) {
    c->mgr = mgr;
    c->send.align = c->recv.align = c->rtls.align = MG_IO_SIZE;
    c->id = ++mgr->nextid;
    MG_PROF_INIT(c);
  }
  return c;
}

void mg_close_conn(struct mg_connection *c) {
  mg_resolve_cancel(c);  // Close any pending DNS query
  LIST_DELETE(struct mg_connection, &c->mgr->conns, c);
  if (c == c->mgr->dns4.c) c->mgr->dns4.c = NULL;
  if (c == c->mgr->dns6.c) c->mgr->dns6.c = NULL;
  // Order of operations is important. `MG_EV_CLOSE` event must be fired
  // before we deallocate received data, see #1331
  mg_call(c, MG_EV_CLOSE, NULL);
  MG_DEBUG(("%lu %ld closed", c->id, c->fd));
  MG_PROF_DUMP(c);
  MG_PROF_FREE(c);

  mg_tls_free(c);
  mg_iobuf_free(&c->recv);
  mg_iobuf_free(&c->send);
  mg_iobuf_free(&c->rtls);
  mg_bzero((unsigned char *) c, sizeof(*c));
  free(c);
}

struct mg_connection *mg_connect(struct mg_mgr *mgr, const char *url,
                                 mg_event_handler_t fn, void *fn_data) {
  struct mg_connection *c = NULL;
  if (url == NULL || url[0] == '\0') {
    MG_ERROR(("null url"));
  } else if ((c = mg_alloc_conn(mgr)) == NULL) {
    MG_ERROR(("OOM"));
  } else {
    LIST_ADD_HEAD(struct mg_connection, &mgr->conns, c);
    c->is_udp = (strncmp(url, "udp:", 4) == 0);
    c->fd = (void *) (size_t) MG_INVALID_SOCKET;
    c->fn = fn;
    c->is_client = true;
    c->fn_data = fn_data;
    MG_DEBUG(("%lu %ld %s", c->id, c->fd, url));
    mg_call(c, MG_EV_OPEN, (void *) url);
    mg_resolve(c, url);
  }
  return c;
}

struct mg_connection *mg_listen(struct mg_mgr *mgr, const char *url,
                                mg_event_handler_t fn, void *fn_data) {
  struct mg_connection *c = NULL;
  if ((c = mg_alloc_conn(mgr)) == NULL) {
    MG_ERROR(("OOM %s", url));
  } else if (!mg_open_listener(c, url)) {
    MG_ERROR(("Failed: %s, errno %d", url, errno));
    MG_PROF_FREE(c);
    free(c);
    c = NULL;
  } else {
    c->is_listening = 1;
    c->is_udp = strncmp(url, "udp:", 4) == 0;
    LIST_ADD_HEAD(struct mg_connection, &mgr->conns, c);
    c->fn = fn;
    c->fn_data = fn_data;
    mg_call(c, MG_EV_OPEN, NULL);
    if (mg_url_is_ssl(url)) c->is_tls = 1;  // Accepted connection must
    MG_DEBUG(("%lu %ld %s", c->id, c->fd, url));
  }
  return c;
}

struct mg_connection *mg_wrapfd(struct mg_mgr *mgr, int fd,
                                mg_event_handler_t fn, void *fn_data) {
  struct mg_connection *c = mg_alloc_conn(mgr);
  if (c != NULL) {
    c->fd = (void *) (size_t) fd;
    c->fn = fn;
    c->fn_data = fn_data;
    MG_EPOLL_ADD(c);
    mg_call(c, MG_EV_OPEN, NULL);
    LIST_ADD_HEAD(struct mg_connection, &mgr->conns, c);
  }
  return c;
}

struct mg_timer *mg_timer_add(struct mg_mgr *mgr, uint64_t milliseconds,
                              unsigned flags, void (*fn)(void *), void *arg) {
  struct mg_timer *t = (struct mg_timer *) calloc(1, sizeof(*t));
  if (t != NULL) {
    mg_timer_init(&mgr->timers, t, milliseconds, flags, fn, arg);
    t->id = mgr->timerid++;
  }
  return t;
}

long mg_io_recv(struct mg_connection *c, void *buf, size_t len) {
  if (c->rtls.len == 0) return MG_IO_WAIT;
  if (len > c->rtls.len) len = c->rtls.len;
  memcpy(buf, c->rtls.buf, len);
  mg_iobuf_del(&c->rtls, 0, len);
  return (long) len;
}

void mg_mgr_free(struct mg_mgr *mgr) {
  struct mg_connection *c;
  struct mg_timer *tmp, *t = mgr->timers;
  while (t != NULL) tmp = t->next, free(t), t = tmp;
  mgr->timers = NULL;  // Important. Next call to poll won't touch timers
  for (c = mgr->conns; c != NULL; c = c->next) c->is_closing = 1;
  mg_mgr_poll(mgr, 0);
#if MG_ENABLE_FREERTOS_TCP
  FreeRTOS_DeleteSocketSet(mgr->ss);
#endif
  MG_DEBUG(("All connections closed"));
#if MG_ENABLE_EPOLL
  if (mgr->epoll_fd >= 0) close(mgr->epoll_fd), mgr->epoll_fd = -1;
#endif
  mg_tls_ctx_free(mgr);
}

void mg_mgr_init(struct mg_mgr *mgr) {
  memset(mgr, 0, sizeof(*mgr));
#if MG_ENABLE_EPOLL
  if ((mgr->epoll_fd = epoll_create1(EPOLL_CLOEXEC)) < 0)
    MG_ERROR(("epoll_create1 errno %d", errno));
#else
  mgr->epoll_fd = -1;
#endif
#if MG_ARCH == MG_ARCH_WIN32 && MG_ENABLE_WINSOCK
  // clang-format off
  { WSADATA data; WSAStartup(MAKEWORD(2, 2), &data); }
  // clang-format on
#elif MG_ENABLE_FREERTOS_TCP
  mgr->ss = FreeRTOS_CreateSocketSet();
#elif defined(__unix) || defined(__unix__) || defined(__APPLE__)
  // Ignore SIGPIPE signal, so if client cancels the request, it
  // won't kill the whole process.
  signal(SIGPIPE, SIG_IGN);
#elif MG_ENABLE_TCPIP_DRIVER_INIT && defined(MG_TCPIP_DRIVER_INIT)
  MG_TCPIP_DRIVER_INIT(mgr);
#endif
  mgr->pipe = MG_INVALID_SOCKET;
  mgr->dnstimeout = 3000;
  mgr->dns4.url = "udp://8.8.8.8:53";
  mgr->dns6.url = "udp://[2001:4860:4860::8888]:53";
  mg_tls_ctx_init(mgr);
}

#ifdef MG_ENABLE_LINES
#line 1 "src/net_builtin.c"
#endif


#if defined(MG_ENABLE_TCPIP) && MG_ENABLE_TCPIP
#define MG_EPHEMERAL_PORT_BASE 32768
#define PDIFF(a, b) ((size_t) (((char *) (b)) - ((char *) (a))))

#ifndef MIP_TCP_KEEPALIVE_MS
#define MIP_TCP_KEEPALIVE_MS 45000  // TCP keep-alive period, ms
#endif

#define MIP_TCP_ACK_MS 150    // Timeout for ACKing
#define MIP_ARP_RESP_MS 100   // Timeout for ARP response
#define MIP_TCP_SYN_MS 15000  // Timeout for connection establishment
#define MIP_TCP_FIN_MS 1000   // Timeout for closing connection
#define MIP_TCP_WIN 6000      // TCP window size

struct connstate {
  uint32_t seq, ack;           // TCP seq/ack counters
  uint64_t timer;              // TCP keep-alive / ACK timer
  uint32_t acked;              // Last ACK-ed number
  size_t unacked;              // Not acked bytes
  uint8_t mac[6];              // Peer MAC address
  uint8_t ttype;               // Timer type. 0: ack, 1: keep-alive
#define MIP_TTYPE_KEEPALIVE 0  // Connection is idle for long, send keepalive
#define MIP_TTYPE_ACK 1        // Peer sent us data, we have to ack it soon
#define MIP_TTYPE_ARP 2        // ARP resolve sent, waiting for response
#define MIP_TTYPE_SYN 3        // SYN sent, waiting for response
#define MIP_TTYPE_FIN 4  // FIN sent, waiting until terminating the connection
  uint8_t tmiss;         // Number of keep-alive misses
  struct mg_iobuf raw;   // For TLS only. Incoming raw data
  bool fin_rcvd;         // We have received FIN from the peer
  bool twclosure;        // 3-way closure done
};

#pragma pack(push, 1)

struct lcp {
  uint8_t addr, ctrl, proto[2], code, id, len[2];
};

struct eth {
  uint8_t dst[6];  // Destination MAC address
  uint8_t src[6];  // Source MAC address
  uint16_t type;   // Ethernet type
};

struct ip {
  uint8_t ver;    // Version
  uint8_t tos;    // Unused
  uint16_t len;   // Length
  uint16_t id;    // Unused
  uint16_t frag;  // Fragmentation
#define IP_FRAG_OFFSET_MSK 0x1fff
#define IP_MORE_FRAGS_MSK 0x2000
  uint8_t ttl;    // Time to live
  uint8_t proto;  // Upper level protocol
  uint16_t csum;  // Checksum
  uint32_t src;   // Source IP
  uint32_t dst;   // Destination IP
};

struct ip6 {
  uint8_t ver;      // Version
  uint8_t opts[3];  // Options
  uint16_t len;     // Length
  uint8_t proto;    // Upper level protocol
  uint8_t ttl;      // Time to live
  uint8_t src[16];  // Source IP
  uint8_t dst[16];  // Destination IP
};

struct icmp {
  uint8_t type;
  uint8_t code;
  uint16_t csum;
};

struct arp {
  uint16_t fmt;    // Format of hardware address
  uint16_t pro;    // Format of protocol address
  uint8_t hlen;    // Length of hardware address
  uint8_t plen;    // Length of protocol address
  uint16_t op;     // Operation
  uint8_t sha[6];  // Sender hardware address
  uint32_t spa;    // Sender protocol address
  uint8_t tha[6];  // Target hardware address
  uint32_t tpa;    // Target protocol address
};

struct tcp {
  uint16_t sport;  // Source port
  uint16_t dport;  // Destination port
  uint32_t seq;    // Sequence number
  uint32_t ack;    // Acknowledgement number
  uint8_t off;     // Data offset
  uint8_t flags;   // TCP flags
#define TH_FIN 0x01
#define TH_SYN 0x02
#define TH_RST 0x04
#define TH_PUSH 0x08
#define TH_ACK 0x10
#define TH_URG 0x20
#define TH_ECE 0x40
#define TH_CWR 0x80
  uint16_t win;   // Window
  uint16_t csum;  // Checksum
  uint16_t urp;   // Urgent pointer
};

struct udp {
  uint16_t sport;  // Source port
  uint16_t dport;  // Destination port
  uint16_t len;    // UDP length
  uint16_t csum;   // UDP checksum
};

struct dhcp {
  uint8_t op, htype, hlen, hops;
  uint32_t xid;
  uint16_t secs, flags;
  uint32_t ciaddr, yiaddr, siaddr, giaddr;
  uint8_t hwaddr[208];
  uint32_t magic;
  uint8_t options[30 + sizeof(((struct mg_tcpip_if *) 0)->dhcp_name)];
};

#pragma pack(pop)

struct pkt {
  struct mg_str raw;  // Raw packet data
  struct mg_str pay;  // Payload data
  struct eth *eth;
  struct llc *llc;
  struct arp *arp;
  struct ip *ip;
  struct ip6 *ip6;
  struct icmp *icmp;
  struct tcp *tcp;
  struct udp *udp;
  struct dhcp *dhcp;
};

static void mg_tcpip_call(struct mg_tcpip_if *ifp, int ev, void *ev_data) {
  if (ifp->fn != NULL) ifp->fn(ifp, ev, ev_data);
}

static void send_syn(struct mg_connection *c);

static void mkpay(struct pkt *pkt, void *p) {
  pkt->pay =
      mg_str_n((char *) p, (size_t) (&pkt->raw.buf[pkt->raw.len] - (char *) p));
}

static uint32_t csumup(uint32_t sum, const void *buf, size_t len) {
  size_t i;
  const uint8_t *p = (const uint8_t *) buf;
  for (i = 0; i < len; i++) sum += i & 1 ? p[i] : ((uint32_t) p[i]) << 8;
  return sum;
}

static uint16_t csumfin(uint32_t sum) {
  while (sum >> 16) sum = (sum & 0xffff) + (sum >> 16);
  return mg_htons(~sum & 0xffff);
}

static uint16_t ipcsum(const void *buf, size_t len) {
  uint32_t sum = csumup(0, buf, len);
  return csumfin(sum);
}

static void settmout(struct mg_connection *c, uint8_t type) {
  struct mg_tcpip_if *ifp = c->mgr->ifp;
  struct connstate *s = (struct connstate *) (c + 1);
  unsigned n = type == MIP_TTYPE_ACK   ? MIP_TCP_ACK_MS
               : type == MIP_TTYPE_ARP ? MIP_ARP_RESP_MS
               : type == MIP_TTYPE_SYN ? MIP_TCP_SYN_MS
               : type == MIP_TTYPE_FIN ? MIP_TCP_FIN_MS
                                       : MIP_TCP_KEEPALIVE_MS;
  s->timer = ifp->now + n;
  s->ttype = type;
  MG_VERBOSE(("%lu %d -> %llx", c->id, type, s->timer));
}

static size_t ether_output(struct mg_tcpip_if *ifp, size_t len) {
  size_t n = ifp->driver->tx(ifp->tx.buf, len, ifp);
  if (n == len) ifp->nsent++;
  return n;
}

void mg_tcpip_arp_request(struct mg_tcpip_if *ifp, uint32_t ip, uint8_t *mac) {
  struct eth *eth = (struct eth *) ifp->tx.buf;
  struct arp *arp = (struct arp *) (eth + 1);
  memset(eth->dst, 255, sizeof(eth->dst));
  memcpy(eth->src, ifp->mac, sizeof(eth->src));
  eth->type = mg_htons(0x806);
  memset(arp, 0, sizeof(*arp));
  arp->fmt = mg_htons(1), arp->pro = mg_htons(0x800), arp->hlen = 6,
  arp->plen = 4;
  arp->op = mg_htons(1), arp->tpa = ip, arp->spa = ifp->ip;
  memcpy(arp->sha, ifp->mac, sizeof(arp->sha));
  if (mac != NULL) memcpy(arp->tha, mac, sizeof(arp->tha));
  ether_output(ifp, PDIFF(eth, arp + 1));
}

static void onstatechange(struct mg_tcpip_if *ifp) {
  if (ifp->state == MG_TCPIP_STATE_READY) {
    MG_INFO(("READY, IP: %M", mg_print_ip4, &ifp->ip));
    MG_INFO(("       GW: %M", mg_print_ip4, &ifp->gw));
    MG_INFO(("      MAC: %M", mg_print_mac, &ifp->mac));
  } else if (ifp->state == MG_TCPIP_STATE_IP) {
    MG_ERROR(("Got IP"));
    mg_tcpip_arp_request(ifp, ifp->gw, NULL);  // unsolicited GW ARP request
  } else if (ifp->state == MG_TCPIP_STATE_UP) {
    MG_ERROR(("Link up"));
    srand((unsigned int) mg_millis());
  } else if (ifp->state == MG_TCPIP_STATE_DOWN) {
    MG_ERROR(("Link down"));
  }
  mg_tcpip_call(ifp, MG_TCPIP_EV_ST_CHG, &ifp->state);
}

static struct ip *tx_ip(struct mg_tcpip_if *ifp, uint8_t *mac_dst,
                        uint8_t proto, uint32_t ip_src, uint32_t ip_dst,
                        size_t plen) {
  struct eth *eth = (struct eth *) ifp->tx.buf;
  struct ip *ip = (struct ip *) (eth + 1);
  memcpy(eth->dst, mac_dst, sizeof(eth->dst));
  memcpy(eth->src, ifp->mac, sizeof(eth->src));  // Use our MAC
  eth->type = mg_htons(0x800);
  memset(ip, 0, sizeof(*ip));
  ip->ver = 0x45;               // Version 4, header length 5 words
  ip->frag = mg_htons(0x4000);  // Don't fragment
  ip->len = mg_htons((uint16_t) (sizeof(*ip) + plen));
  ip->ttl = 64;
  ip->proto = proto;
  ip->src = ip_src;
  ip->dst = ip_dst;
  ip->csum = ipcsum(ip, sizeof(*ip));
  return ip;
}

static void tx_udp(struct mg_tcpip_if *ifp, uint8_t *mac_dst, uint32_t ip_src,
                   uint16_t sport, uint32_t ip_dst, uint16_t dport,
                   const void *buf, size_t len) {
  struct ip *ip =
      tx_ip(ifp, mac_dst, 17, ip_src, ip_dst, len + sizeof(struct udp));
  struct udp *udp = (struct udp *) (ip + 1);
  // MG_DEBUG(("UDP XX LEN %d %d", (int) len, (int) ifp->tx.len));
  udp->sport = sport;
  udp->dport = dport;
  udp->len = mg_htons((uint16_t) (sizeof(*udp) + len));
  udp->csum = 0;
  uint32_t cs = csumup(0, udp, sizeof(*udp));
  cs = csumup(cs, buf, len);
  cs = csumup(cs, &ip->src, sizeof(ip->src));
  cs = csumup(cs, &ip->dst, sizeof(ip->dst));
  cs += (uint32_t) (ip->proto + sizeof(*udp) + len);
  udp->csum = csumfin(cs);
  memmove(udp + 1, buf, len);
  // MG_DEBUG(("UDP LEN %d %d", (int) len, (int) ifp->frame_len));
  ether_output(ifp, sizeof(struct eth) + sizeof(*ip) + sizeof(*udp) + len);
}

static void tx_dhcp(struct mg_tcpip_if *ifp, uint8_t *mac_dst, uint32_t ip_src,
                    uint32_t ip_dst, uint8_t *opts, size_t optslen,
                    bool ciaddr) {
  // https://datatracker.ietf.org/doc/html/rfc2132#section-9.6
  struct dhcp dhcp = {1, 1, 6, 0, 0, 0, 0, 0, 0, 0, 0, {0}, 0, {0}};
  dhcp.magic = mg_htonl(0x63825363);
  memcpy(&dhcp.hwaddr, ifp->mac, sizeof(ifp->mac));
  memcpy(&dhcp.xid, ifp->mac + 2, sizeof(dhcp.xid));
  memcpy(&dhcp.options, opts, optslen);
  if (ciaddr) dhcp.ciaddr = ip_src;
  tx_udp(ifp, mac_dst, ip_src, mg_htons(68), ip_dst, mg_htons(67), &dhcp,
         sizeof(dhcp));
}

static const uint8_t broadcast[] = {255, 255, 255, 255, 255, 255};

// RFC-2131 #4.3.6, #4.4.1; RFC-2132 #9.8
static void tx_dhcp_request_sel(struct mg_tcpip_if *ifp, uint32_t ip_req,
                                uint32_t ip_srv) {
  uint8_t extra = (uint8_t) ((ifp->enable_req_dns ? 1 : 0) +
                             (ifp->enable_req_sntp ? 1 : 0));
  size_t len = strlen(ifp->dhcp_name);
  size_t olen = 21 + len + extra + 2 + 1;   // Total length of options
  uint8_t *opts = alloca(olen), *p = opts;  // Allocate options
  *p++ = 53, *p++ = 1, *p++ = 3;            // Type: DHCP request
  *p++ = 54, *p++ = 4, memcpy(p, &ip_srv, 4), p += 4;  // DHCP server ID
  *p++ = 50, *p++ = 4, memcpy(p, &ip_req, 4), p += 4;  // Requested IP
  *p++ = 12, *p++ = (uint8_t) (len & 255);             // DHCP host
  memcpy(p, ifp->dhcp_name, len), p += len;            // name
  *p++ = 55, *p++ = 2 + extra, *p++ = 1, *p++ = 3;     // GW, MASK
  if (ifp->enable_req_dns) *p++ = 6;                   // DNS
  if (ifp->enable_req_sntp) *p++ = 42;                 // SNTP
  *p++ = 255;                                          // End of options
  // assert((size_t) (p - opts) < olen);
  tx_dhcp(ifp, (uint8_t *) broadcast, 0, 0xffffffff, opts, olen, 0);
  MG_DEBUG(("DHCP req sent"));
}

// RFC-2131 #4.3.6, #4.4.5 (renewing: unicast, rebinding: bcast)
static void tx_dhcp_request_re(struct mg_tcpip_if *ifp, uint8_t *mac_dst,
                               uint32_t ip_src, uint32_t ip_dst) {
  uint8_t opts[] = {
      53, 1, 3,  // Type: DHCP request
      255        // End of options
  };
  tx_dhcp(ifp, mac_dst, ip_src, ip_dst, opts, sizeof(opts), true);
  MG_DEBUG(("DHCP req sent"));
}

static void tx_dhcp_discover(struct mg_tcpip_if *ifp) {
  uint8_t opts[] = {
      53, 1, 1,     // Type: DHCP discover
      55, 2, 1, 3,  // Parameters: ip, mask
      255           // End of options
  };
  tx_dhcp(ifp, (uint8_t *) broadcast, 0, 0xffffffff, opts, sizeof(opts), false);
  MG_DEBUG(("DHCP discover sent. Our MAC: %M", mg_print_mac, ifp->mac));
}

static struct mg_connection *getpeer(struct mg_mgr *mgr, struct pkt *pkt,
                                     bool lsn) {
  struct mg_connection *c = NULL;
  for (c = mgr->conns; c != NULL; c = c->next) {
    if (c->is_arplooking && pkt->arp &&
        memcmp(&pkt->arp->spa, c->rem.ip, sizeof(pkt->arp->spa)) == 0)
      break;
    if (c->is_udp && pkt->udp && c->loc.port == pkt->udp->dport) break;
    if (!c->is_udp && pkt->tcp && c->loc.port == pkt->tcp->dport &&
        lsn == c->is_listening && (lsn || c->rem.port == pkt->tcp->sport))
      break;
  }
  return c;
}

static void mac_resolved(struct mg_connection *c);

static void rx_arp(struct mg_tcpip_if *ifp, struct pkt *pkt) {
  if (pkt->arp->op == mg_htons(1) && pkt->arp->tpa == ifp->ip) {
    // ARP request. Make a response, then send
    // MG_DEBUG(("ARP op %d %M: %M", mg_ntohs(pkt->arp->op), mg_print_ip4,
    //          &pkt->arp->spa, mg_print_ip4, &pkt->arp->tpa));
    struct eth *eth = (struct eth *) ifp->tx.buf;
    struct arp *arp = (struct arp *) (eth + 1);
    memcpy(eth->dst, pkt->eth->src, sizeof(eth->dst));
    memcpy(eth->src, ifp->mac, sizeof(eth->src));
    eth->type = mg_htons(0x806);
    *arp = *pkt->arp;
    arp->op = mg_htons(2);
    memcpy(arp->tha, pkt->arp->sha, sizeof(pkt->arp->tha));
    memcpy(arp->sha, ifp->mac, sizeof(pkt->arp->sha));
    arp->tpa = pkt->arp->spa;
    arp->spa = ifp->ip;
    MG_DEBUG(("ARP: tell %M we're %M", mg_print_ip4, &arp->tpa, mg_print_mac,
              &ifp->mac));
    ether_output(ifp, PDIFF(eth, arp + 1));
  } else if (pkt->arp->op == mg_htons(2)) {
    if (memcmp(pkt->arp->tha, ifp->mac, sizeof(pkt->arp->tha)) != 0) return;
    if (pkt->arp->spa == ifp->gw) {
      // Got response for the GW ARP request. Set ifp->gwmac and IP -> READY
      memcpy(ifp->gwmac, pkt->arp->sha, sizeof(ifp->gwmac));
      if (ifp->state == MG_TCPIP_STATE_IP) {
        ifp->state = MG_TCPIP_STATE_READY;
        onstatechange(ifp);
      }
    } else {
      struct mg_connection *c = getpeer(ifp->mgr, pkt, false);
      if (c != NULL && c->is_arplooking) {
        struct connstate *s = (struct connstate *) (c + 1);
        memcpy(s->mac, pkt->arp->sha, sizeof(s->mac));
        MG_DEBUG(("%lu ARP resolved %M -> %M", c->id, mg_print_ip4, c->rem.ip,
                  mg_print_mac, s->mac));
        c->is_arplooking = 0;
        mac_resolved(c);
      }
    }
  }
}

static void rx_icmp(struct mg_tcpip_if *ifp, struct pkt *pkt) {
  // MG_DEBUG(("ICMP %d", (int) len));
  if (pkt->icmp->type == 8 && pkt->ip != NULL && pkt->ip->dst == ifp->ip) {
    size_t hlen = sizeof(struct eth) + sizeof(struct ip) + sizeof(struct icmp);
    size_t space = ifp->tx.len - hlen, plen = pkt->pay.len;
    if (plen > space) plen = space;
    struct ip *ip = tx_ip(ifp, pkt->eth->src, 1, ifp->ip, pkt->ip->src,
                          sizeof(struct icmp) + plen);
    struct icmp *icmp = (struct icmp *) (ip + 1);
    memset(icmp, 0, sizeof(*icmp));        // Set csum to 0
    memcpy(icmp + 1, pkt->pay.buf, plen);  // Copy RX payload to TX
    icmp->csum = ipcsum(icmp, sizeof(*icmp) + plen);
    ether_output(ifp, hlen + plen);
  }
}

static void rx_dhcp_client(struct mg_tcpip_if *ifp, struct pkt *pkt) {
  uint32_t ip = 0, gw = 0, mask = 0, lease = 0, dns = 0, sntp = 0;
  uint8_t msgtype = 0, state = ifp->state;
  // perform size check first, then access fields
  uint8_t *p = pkt->dhcp->options,
          *end = (uint8_t *) &pkt->raw.buf[pkt->raw.len];
  if (end < (uint8_t *) (pkt->dhcp + 1)) return;
  if (memcmp(&pkt->dhcp->xid, ifp->mac + 2, sizeof(pkt->dhcp->xid))) return;
  while (p + 1 < end && p[0] != 255) {  // Parse options RFC-1533 #9
    if (p[0] == 1 && p[1] == sizeof(ifp->mask) && p + 6 < end) {  // Mask
      memcpy(&mask, p + 2, sizeof(mask));
    } else if (p[0] == 3 && p[1] == sizeof(ifp->gw) && p + 6 < end) {  // GW
      memcpy(&gw, p + 2, sizeof(gw));
      ip = pkt->dhcp->yiaddr;
    } else if (ifp->enable_req_dns && p[0] == 6 && p[1] == sizeof(dns) &&
               p + 6 < end) {  // DNS
      memcpy(&dns, p + 2, sizeof(dns));
    } else if (ifp->enable_req_sntp && p[0] == 42 && p[1] == sizeof(sntp) &&
               p + 6 < end) {  // SNTP
      memcpy(&sntp, p + 2, sizeof(sntp));
    } else if (p[0] == 51 && p[1] == 4 && p + 6 < end) {  // Lease
      memcpy(&lease, p + 2, sizeof(lease));
      lease = mg_ntohl(lease);
    } else if (p[0] == 53 && p[1] == 1 && p + 6 < end) {  // Msg Type
      msgtype = p[2];
    }
    p += p[1] + 2;
  }
  // Process message type, RFC-1533 (9.4); RFC-2131 (3.1, 4)
  if (msgtype == 6 && ifp->ip == ip) {  // DHCPNACK, release IP
    ifp->state = MG_TCPIP_STATE_UP, ifp->ip = 0;
  } else if (msgtype == 2 && ifp->state == MG_TCPIP_STATE_UP && ip && gw &&
             lease) {  // DHCPOFFER
    // select IP, (4.4.1) (fallback to IP source addr on foul play)
    tx_dhcp_request_sel(ifp, ip,
                        pkt->dhcp->siaddr ? pkt->dhcp->siaddr : pkt->ip->src);
    ifp->state = MG_TCPIP_STATE_REQ;  // REQUESTING state
  } else if (msgtype == 5) {          // DHCPACK
    if (ifp->state == MG_TCPIP_STATE_REQ && ip && gw && lease) {  // got an IP
      ifp->lease_expire = ifp->now + lease * 1000;
      MG_INFO(("Lease: %u sec (%lld)", lease, ifp->lease_expire / 1000));
      // assume DHCP server = router until ARP resolves
      memcpy(ifp->gwmac, pkt->eth->src, sizeof(ifp->gwmac));
      ifp->ip = ip, ifp->gw = gw, ifp->mask = mask;
      ifp->state = MG_TCPIP_STATE_IP;  // BOUND state
      uint64_t rand;
      mg_random(&rand, sizeof(rand));
      srand((unsigned int) (rand + mg_millis()));
      if (ifp->enable_req_dns && dns != 0)
        mg_tcpip_call(ifp, MG_TCPIP_EV_DHCP_DNS, &dns);
      if (ifp->enable_req_sntp && sntp != 0)
        mg_tcpip_call(ifp, MG_TCPIP_EV_DHCP_SNTP, &sntp);
    } else if (ifp->state == MG_TCPIP_STATE_READY && ifp->ip == ip) {  // renew
      ifp->lease_expire = ifp->now + lease * 1000;
      MG_INFO(("Lease: %u sec (%lld)", lease, ifp->lease_expire / 1000));
    }  // TODO(): accept provided T1/T2 and store server IP for renewal (4.4)
  }
  if (ifp->state != state) onstatechange(ifp);
}

// Simple DHCP server that assigns a next IP address: ifp->ip + 1
static void rx_dhcp_server(struct mg_tcpip_if *ifp, struct pkt *pkt) {
  uint8_t op = 0, *p = pkt->dhcp->options,
          *end = (uint8_t *) &pkt->raw.buf[pkt->raw.len];
  if (end < (uint8_t *) (pkt->dhcp + 1)) return;
  // struct dhcp *req = pkt->dhcp;
  struct dhcp res = {2, 1, 6, 0, 0, 0, 0, 0, 0, 0, 0, {0}, 0, {0}};
  res.yiaddr = ifp->ip;
  ((uint8_t *) (&res.yiaddr))[3]++;                // Offer our IP + 1
  while (p + 1 < end && p[0] != 255) {             // Parse options
    if (p[0] == 53 && p[1] == 1 && p + 2 < end) {  // Message type
      op = p[2];
    }
    p += p[1] + 2;
  }
  if (op == 1 || op == 3) {         // DHCP Discover or DHCP Request
    uint8_t msg = op == 1 ? 2 : 5;  // Message type: DHCP OFFER or DHCP ACK
    uint8_t opts[] = {
        53, 1, msg,                 // Message type
        1,  4, 0,   0,   0,   0,    // Subnet mask
        54, 4, 0,   0,   0,   0,    // Server ID
        12, 3, 'm', 'i', 'p',       // Host name: "mip"
        51, 4, 255, 255, 255, 255,  // Lease time
        255                         // End of options
    };
    memcpy(&res.hwaddr, pkt->dhcp->hwaddr, 6);
    memcpy(opts + 5, &ifp->mask, sizeof(ifp->mask));
    memcpy(opts + 11, &ifp->ip, sizeof(ifp->ip));
    memcpy(&res.options, opts, sizeof(opts));
    res.magic = pkt->dhcp->magic;
    res.xid = pkt->dhcp->xid;
    if (ifp->enable_get_gateway) {
      ifp->gw = res.yiaddr;  // set gw IP, best-effort gwmac as DHCP server's
      memcpy(ifp->gwmac, pkt->eth->src, sizeof(ifp->gwmac));
    }
    tx_udp(ifp, pkt->eth->src, ifp->ip, mg_htons(67),
           op == 1 ? ~0U : res.yiaddr, mg_htons(68), &res, sizeof(res));
  }
}

static void rx_udp(struct mg_tcpip_if *ifp, struct pkt *pkt) {
  struct mg_connection *c = getpeer(ifp->mgr, pkt, true);
  if (c == NULL) {
    // No UDP listener on this port. Should send ICMP, but keep silent.
  } else {
    c->rem.port = pkt->udp->sport;
    memcpy(c->rem.ip, &pkt->ip->src, sizeof(uint32_t));
    struct connstate *s = (struct connstate *) (c + 1);
    memcpy(s->mac, pkt->eth->src, sizeof(s->mac));
    if (c->recv.len >= MG_MAX_RECV_SIZE) {
      mg_error(c, "max_recv_buf_size reached");
    } else if (c->recv.size - c->recv.len < pkt->pay.len &&
               !mg_iobuf_resize(&c->recv, c->recv.len + pkt->pay.len)) {
      mg_error(c, "oom");
    } else {
      memcpy(&c->recv.buf[c->recv.len], pkt->pay.buf, pkt->pay.len);
      c->recv.len += pkt->pay.len;
      mg_call(c, MG_EV_READ, &pkt->pay.len);
    }
  }
}

static size_t tx_tcp(struct mg_tcpip_if *ifp, uint8_t *dst_mac, uint32_t dst_ip,
                     uint8_t flags, uint16_t sport, uint16_t dport,
                     uint32_t seq, uint32_t ack, const void *buf, size_t len) {
#if 0
  uint8_t opts[] = {2, 4, 5, 0xb4, 4, 2, 0, 0};  // MSS = 1460, SACK permitted
  if (flags & TH_SYN) {
    // Handshake? Set MSS
    buf = opts;
    len = sizeof(opts);
  }
#endif
  struct ip *ip =
      tx_ip(ifp, dst_mac, 6, ifp->ip, dst_ip, sizeof(struct tcp) + len);
  struct tcp *tcp = (struct tcp *) (ip + 1);
  memset(tcp, 0, sizeof(*tcp));
  if (buf != NULL && len) memmove(tcp + 1, buf, len);
  tcp->sport = sport;
  tcp->dport = dport;
  tcp->seq = seq;
  tcp->ack = ack;
  tcp->flags = flags;
  tcp->win = mg_htons(MIP_TCP_WIN);
  tcp->off = (uint8_t) (sizeof(*tcp) / 4 << 4);
  // if (flags & TH_SYN) tcp->off = 0x70;  // Handshake? header size 28 bytes

  uint32_t cs = 0;
  uint16_t n = (uint16_t) (sizeof(*tcp) + len);
  uint8_t pseudo[] = {0, ip->proto, (uint8_t) (n >> 8), (uint8_t) (n & 255)};
  cs = csumup(cs, tcp, n);
  cs = csumup(cs, &ip->src, sizeof(ip->src));
  cs = csumup(cs, &ip->dst, sizeof(ip->dst));
  cs = csumup(cs, pseudo, sizeof(pseudo));
  tcp->csum = csumfin(cs);
  MG_VERBOSE(("TCP %M:%hu -> %M:%hu fl %x len %u", mg_print_ip4, &ip->src,
              mg_ntohs(tcp->sport), mg_print_ip4, &ip->dst,
              mg_ntohs(tcp->dport), tcp->flags, len));
  // mg_hexdump(ifp->tx.buf, PDIFF(ifp->tx.buf, tcp + 1) + len);
  return ether_output(ifp, PDIFF(ifp->tx.buf, tcp + 1) + len);
}

static size_t tx_tcp_pkt(struct mg_tcpip_if *ifp, struct pkt *pkt,
                         uint8_t flags, uint32_t seq, const void *buf,
                         size_t len) {
  uint32_t delta = (pkt->tcp->flags & (TH_SYN | TH_FIN)) ? 1 : 0;
  return tx_tcp(ifp, pkt->eth->src, pkt->ip->src, flags, pkt->tcp->dport,
                pkt->tcp->sport, seq, mg_htonl(mg_ntohl(pkt->tcp->seq) + delta),
                buf, len);
}

static struct mg_connection *accept_conn(struct mg_connection *lsn,
                                         struct pkt *pkt) {
  struct mg_connection *c = mg_alloc_conn(lsn->mgr);
  if (c == NULL) {
    MG_ERROR(("OOM"));
    return NULL;
  }
  struct connstate *s = (struct connstate *) (c + 1);
  s->seq = mg_ntohl(pkt->tcp->ack), s->ack = mg_ntohl(pkt->tcp->seq);
  memcpy(s->mac, pkt->eth->src, sizeof(s->mac));
  settmout(c, MIP_TTYPE_KEEPALIVE);
  memcpy(c->rem.ip, &pkt->ip->src, sizeof(uint32_t));
  c->rem.port = pkt->tcp->sport;
  MG_DEBUG(("%lu accepted %M", c->id, mg_print_ip_port, &c->rem));
  LIST_ADD_HEAD(struct mg_connection, &lsn->mgr->conns, c);
  c->is_accepted = 1;
  c->is_hexdumping = lsn->is_hexdumping;
  c->pfn = lsn->pfn;
  c->loc = lsn->loc;
  c->pfn_data = lsn->pfn_data;
  c->fn = lsn->fn;
  c->fn_data = lsn->fn_data;
  mg_call(c, MG_EV_OPEN, NULL);
  mg_call(c, MG_EV_ACCEPT, NULL);
  return c;
}

static size_t trim_len(struct mg_connection *c, size_t len) {
  struct mg_tcpip_if *ifp = c->mgr->ifp;
  size_t eth_h_len = 14, ip_max_h_len = 24, tcp_max_h_len = 60, udp_h_len = 8;
  size_t max_headers_len =
      eth_h_len + ip_max_h_len + (c->is_udp ? udp_h_len : tcp_max_h_len);
  size_t min_mtu = c->is_udp ? 68 /* RFC-791 */ : max_headers_len - eth_h_len;

  // If the frame exceeds the available buffer, trim the length
  if (len + max_headers_len > ifp->tx.len) {
    len = ifp->tx.len - max_headers_len;
  }
  // Ensure the MTU isn't lower than the minimum allowed value
  if (ifp->mtu < min_mtu) {
    MG_ERROR(("MTU is lower than minimum, capping to %lu", min_mtu));
    ifp->mtu = (uint16_t) min_mtu;
  }
  // If the total packet size exceeds the MTU, trim the length
  if (len + max_headers_len - eth_h_len > ifp->mtu) {
    len = ifp->mtu - max_headers_len + eth_h_len;
    if (c->is_udp) {
      MG_ERROR(("UDP datagram exceeds MTU. Truncating it."));
    }
  }

  return len;
}

long mg_io_send(struct mg_connection *c, const void *buf, size_t len) {
  struct mg_tcpip_if *ifp = c->mgr->ifp;
  struct connstate *s = (struct connstate *) (c + 1);
  uint32_t dst_ip = *(uint32_t *) c->rem.ip;
  len = trim_len(c, len);
  if (c->is_udp) {
    tx_udp(ifp, s->mac, ifp->ip, c->loc.port, dst_ip, c->rem.port, buf, len);
  } else {
    size_t sent =
        tx_tcp(ifp, s->mac, dst_ip, TH_PUSH | TH_ACK, c->loc.port, c->rem.port,
               mg_htonl(s->seq), mg_htonl(s->ack), buf, len);
    if (sent == 0) {
      return MG_IO_WAIT;
    } else if (sent == (size_t) -1) {
      return MG_IO_ERR;
    } else {
      s->seq += (uint32_t) len;
      if (s->ttype == MIP_TTYPE_ACK) settmout(c, MIP_TTYPE_KEEPALIVE);
    }
  }
  return (long) len;
}

static void handle_tls_recv(struct mg_connection *c) {
  size_t avail = mg_tls_pending(c);
  size_t min = avail > MG_MAX_RECV_SIZE ? MG_MAX_RECV_SIZE : avail;
  struct mg_iobuf *io = &c->recv;
  if (io->size - io->len < min && !mg_iobuf_resize(io, io->len + min)) {
    mg_error(c, "oom");
  } else {
    // Decrypt data directly into c->recv
    long n = mg_tls_recv(c, io->buf != NULL ? &io->buf[io->len] : io->buf,
                         io->size - io->len);
    if (n == MG_IO_ERR) {
      mg_error(c, "TLS recv error");
    } else if (n > 0) {
      // Decrypted successfully - trigger MG_EV_READ
      io->len += (size_t) n;
      mg_call(c, MG_EV_READ, &n);
    }  // else n < 0: outstanding data to be moved to c->recv
  }
}

static void read_conn(struct mg_connection *c, struct pkt *pkt) {
  struct connstate *s = (struct connstate *) (c + 1);
  struct mg_iobuf *io = c->is_tls ? &c->rtls : &c->recv;
  uint32_t seq = mg_ntohl(pkt->tcp->seq);
  uint32_t rem_ip;
  memcpy(&rem_ip, c->rem.ip, sizeof(uint32_t));
  if (pkt->tcp->flags & TH_FIN) {
    // If we initiated the closure, we reply with ACK upon receiving FIN
    // If we didn't initiate it, we reply with FIN as part of the normal TCP
    // closure process
    uint8_t flags = TH_ACK;
    s->ack = (uint32_t) (mg_htonl(pkt->tcp->seq) + pkt->pay.len + 1);
    s->fin_rcvd = true;
    if (c->is_draining && s->ttype == MIP_TTYPE_FIN) {
      if (s->seq == mg_htonl(pkt->tcp->ack)) {  // Simultaneous closure ?
        s->seq++;                               // Yes. Increment our SEQ
      } else {                                  // Otherwise,
        s->seq = mg_htonl(pkt->tcp->ack);       // Set to peer's ACK
      }
      s->twclosure = true;
    } else {
      flags |= TH_FIN;
      c->is_draining = 1;
      settmout(c, MIP_TTYPE_FIN);
    }
    tx_tcp(c->mgr->ifp, s->mac, rem_ip, flags, c->loc.port, c->rem.port,
           mg_htonl(s->seq), mg_htonl(s->ack), "", 0);
  } else if (pkt->pay.len == 0) {  // this is an ACK
    if (s->fin_rcvd && s->ttype == MIP_TTYPE_FIN) s->twclosure = true;
  } else if (seq != s->ack) {
    uint32_t ack = (uint32_t) (mg_htonl(pkt->tcp->seq) + pkt->pay.len);
    if (s->ack == ack) {
      MG_VERBOSE(("ignoring duplicate pkt"));
    } else {
      MG_VERBOSE(("SEQ != ACK: %x %x %x", seq, s->ack, ack));
      tx_tcp(c->mgr->ifp, s->mac, rem_ip, TH_ACK, c->loc.port, c->rem.port,
             mg_htonl(s->seq), mg_htonl(s->ack), "", 0);
    }
  } else if (io->size - io->len < pkt->pay.len &&
             !mg_iobuf_resize(io, io->len + pkt->pay.len)) {
    mg_error(c, "oom");
  } else {
    // Copy TCP payload into the IO buffer. If the connection is plain text,
    // we copy to c->recv. If the connection is TLS, this data is encrypted,
    // therefore we copy that encrypted data to the c->rtls iobuffer instead,
    // and then call mg_tls_recv() to decrypt it. NOTE: mg_tls_recv() will
    // call back mg_io_recv() which grabs raw data from c->rtls
    memcpy(&io->buf[io->len], pkt->pay.buf, pkt->pay.len);
    io->len += pkt->pay.len;

    MG_VERBOSE(("%lu SEQ %x -> %x", c->id, mg_htonl(pkt->tcp->seq), s->ack));
    // Advance ACK counter
    s->ack = (uint32_t) (mg_htonl(pkt->tcp->seq) + pkt->pay.len);
    s->unacked += pkt->pay.len;
    // size_t diff = s->acked <= s->ack ? s->ack - s->acked : s->ack;
    if (s->unacked > MIP_TCP_WIN / 2 && s->acked != s->ack) {
      // Send ACK immediately
      MG_VERBOSE(("%lu imm ACK %lu", c->id, s->acked));
      tx_tcp(c->mgr->ifp, s->mac, rem_ip, TH_ACK, c->loc.port, c->rem.port,
             mg_htonl(s->seq), mg_htonl(s->ack), NULL, 0);
      s->unacked = 0;
      s->acked = s->ack;
      if (s->ttype != MIP_TTYPE_KEEPALIVE) settmout(c, MIP_TTYPE_KEEPALIVE);
    } else {
      // if not already running, setup a timer to send an ACK later
      if (s->ttype != MIP_TTYPE_ACK) settmout(c, MIP_TTYPE_ACK);
    }

    if (c->is_tls && c->is_tls_hs) {
      mg_tls_handshake(c);
    } else if (c->is_tls) {
      handle_tls_recv(c);
    } else {
      // Plain text connection, data is already in c->recv, trigger MG_EV_READ
      mg_call(c, MG_EV_READ, &pkt->pay.len);
    }
  }
}

static void rx_tcp(struct mg_tcpip_if *ifp, struct pkt *pkt) {
  struct mg_connection *c = getpeer(ifp->mgr, pkt, false);
  struct connstate *s = c == NULL ? NULL : (struct connstate *) (c + 1);
#if 0
  MG_INFO(("%lu %hhu %d", c ? c->id : 0, pkt->tcp->flags, (int) pkt->pay.len));
#endif
  if (c != NULL && c->is_connecting && pkt->tcp->flags == (TH_SYN | TH_ACK)) {
    s->seq = mg_ntohl(pkt->tcp->ack), s->ack = mg_ntohl(pkt->tcp->seq) + 1;
    tx_tcp_pkt(ifp, pkt, TH_ACK, pkt->tcp->ack, NULL, 0);
    c->is_connecting = 0;  // Client connected
    settmout(c, MIP_TTYPE_KEEPALIVE);
    mg_call(c, MG_EV_CONNECT, NULL);  // Let user know
    if (c->is_tls_hs) mg_tls_handshake(c);
  } else if (c != NULL && c->is_connecting && pkt->tcp->flags != TH_ACK) {
    // mg_hexdump(pkt->raw.buf, pkt->raw.len);
    tx_tcp_pkt(ifp, pkt, TH_RST | TH_ACK, pkt->tcp->ack, NULL, 0);
  } else if (c != NULL && pkt->tcp->flags & TH_RST) {
    mg_error(c, "peer RST");  // RFC-1122 4.2.2.13
  } else if (c != NULL) {
#if 0
    MG_DEBUG(("%lu %d %M:%hu -> %M:%hu", c->id, (int) pkt->raw.len,
              mg_print_ip4, &pkt->ip->src, mg_ntohs(pkt->tcp->sport),
              mg_print_ip4, &pkt->ip->dst, mg_ntohs(pkt->tcp->dport)));
    mg_hexdump(pkt->pay.buf, pkt->pay.len);
#endif
    s->tmiss = 0;                         // Reset missed keep-alive counter
    if (s->ttype == MIP_TTYPE_KEEPALIVE)  // Advance keep-alive timer
      settmout(c,
               MIP_TTYPE_KEEPALIVE);  // unless a former ACK timeout is pending
    read_conn(c, pkt);  // Override timer with ACK timeout if needed
  } else if ((c = getpeer(ifp->mgr, pkt, true)) == NULL) {
    tx_tcp_pkt(ifp, pkt, TH_RST | TH_ACK, pkt->tcp->ack, NULL, 0);
  } else if (pkt->tcp->flags & TH_RST) {
    if (c->is_accepted) mg_error(c, "peer RST");  // RFC-1122 4.2.2.13
    // ignore RST if not connected
  } else if (pkt->tcp->flags & TH_SYN) {
    // Use peer's source port as ISN, in order to recognise the handshake
    uint32_t isn = mg_htonl((uint32_t) mg_ntohs(pkt->tcp->sport));
    tx_tcp_pkt(ifp, pkt, TH_SYN | TH_ACK, isn, NULL, 0);
  } else if (pkt->tcp->flags & TH_FIN) {
    tx_tcp_pkt(ifp, pkt, TH_FIN | TH_ACK, pkt->tcp->ack, NULL, 0);
  } else if (mg_htonl(pkt->tcp->ack) == mg_htons(pkt->tcp->sport) + 1U) {
    accept_conn(c, pkt);
  } else if (!c->is_accepted) {  // no peer
    tx_tcp_pkt(ifp, pkt, TH_RST | TH_ACK, pkt->tcp->ack, NULL, 0);
  } else {
    // MG_VERBOSE(("dropped silently.."));
  }
}

static void rx_ip(struct mg_tcpip_if *ifp, struct pkt *pkt) {
  uint16_t frag = mg_ntohs(pkt->ip->frag);
  if (frag & IP_MORE_FRAGS_MSK || frag & IP_FRAG_OFFSET_MSK) {
    if (pkt->ip->proto == 17) pkt->udp = (struct udp *) (pkt->ip + 1);
    if (pkt->ip->proto == 6) pkt->tcp = (struct tcp *) (pkt->ip + 1);
    struct mg_connection *c = getpeer(ifp->mgr, pkt, false);
    if (c) mg_error(c, "Received fragmented packet");
  } else if (pkt->ip->proto == 1) {
    pkt->icmp = (struct icmp *) (pkt->ip + 1);
    if (pkt->pay.len < sizeof(*pkt->icmp)) return;
    mkpay(pkt, pkt->icmp + 1);
    rx_icmp(ifp, pkt);
  } else if (pkt->ip->proto == 17) {
    pkt->udp = (struct udp *) (pkt->ip + 1);
    if (pkt->pay.len < sizeof(*pkt->udp)) return;
    mkpay(pkt, pkt->udp + 1);
    MG_VERBOSE(("UDP %M:%hu -> %M:%hu len %u", mg_print_ip4, &pkt->ip->src,
                mg_ntohs(pkt->udp->sport), mg_print_ip4, &pkt->ip->dst,
                mg_ntohs(pkt->udp->dport), (int) pkt->pay.len));
    if (ifp->enable_dhcp_client && pkt->udp->dport == mg_htons(68)) {
      pkt->dhcp = (struct dhcp *) (pkt->udp + 1);
      mkpay(pkt, pkt->dhcp + 1);
      rx_dhcp_client(ifp, pkt);
    } else if (ifp->enable_dhcp_server && pkt->udp->dport == mg_htons(67)) {
      pkt->dhcp = (struct dhcp *) (pkt->udp + 1);
      mkpay(pkt, pkt->dhcp + 1);
      rx_dhcp_server(ifp, pkt);
    } else {
      rx_udp(ifp, pkt);
    }
  } else if (pkt->ip->proto == 6) {
    pkt->tcp = (struct tcp *) (pkt->ip + 1);
    if (pkt->pay.len < sizeof(*pkt->tcp)) return;
    mkpay(pkt, pkt->tcp + 1);
    uint16_t iplen = mg_ntohs(pkt->ip->len);
    uint16_t off = (uint16_t) (sizeof(*pkt->ip) + ((pkt->tcp->off >> 4) * 4U));
    if (iplen >= off) pkt->pay.len = (size_t) (iplen - off);
    MG_VERBOSE(("TCP %M:%hu -> %M:%hu len %u", mg_print_ip4, &pkt->ip->src,
                mg_ntohs(pkt->tcp->sport), mg_print_ip4, &pkt->ip->dst,
                mg_ntohs(pkt->tcp->dport), (int) pkt->pay.len));
    rx_tcp(ifp, pkt);
  }
}

static void rx_ip6(struct mg_tcpip_if *ifp, struct pkt *pkt) {
  // MG_DEBUG(("IP %d", (int) len));
  if (pkt->ip6->proto == 1 || pkt->ip6->proto == 58) {
    pkt->icmp = (struct icmp *) (pkt->ip6 + 1);
    if (pkt->pay.len < sizeof(*pkt->icmp)) return;
    mkpay(pkt, pkt->icmp + 1);
    rx_icmp(ifp, pkt);
  } else if (pkt->ip6->proto == 17) {
    pkt->udp = (struct udp *) (pkt->ip6 + 1);
    if (pkt->pay.len < sizeof(*pkt->udp)) return;
    // MG_DEBUG(("  UDP %u %u -> %u", len, mg_htons(udp->sport),
    // mg_htons(udp->dport)));
    mkpay(pkt, pkt->udp + 1);
  }
}

static void mg_tcpip_rx(struct mg_tcpip_if *ifp, void *buf, size_t len) {
  struct pkt pkt;
  memset(&pkt, 0, sizeof(pkt));
  pkt.raw.buf = (char *) buf;
  pkt.raw.len = len;
  pkt.eth = (struct eth *) buf;
  // mg_hexdump(buf, len > 16 ? 16: len);
  if (pkt.raw.len < sizeof(*pkt.eth)) return;  // Truncated - runt?
  if (ifp->enable_mac_check &&
      memcmp(pkt.eth->dst, ifp->mac, sizeof(pkt.eth->dst)) != 0 &&
      memcmp(pkt.eth->dst, broadcast, sizeof(pkt.eth->dst)) != 0)
    return;
  if (ifp->enable_crc32_check && len > 4) {
    len -= 4;  // TODO(scaprile): check on bigendian
    uint32_t crc = mg_crc32(0, (const char *) buf, len);
    if (memcmp((void *) ((size_t) buf + len), &crc, sizeof(crc))) return;
  }
  if (pkt.eth->type == mg_htons(0x806)) {
    pkt.arp = (struct arp *) (pkt.eth + 1);
    if (sizeof(*pkt.eth) + sizeof(*pkt.arp) > pkt.raw.len) return;  // Truncated
    mg_tcpip_call(ifp, MG_TCPIP_EV_ARP, &pkt.raw);
    rx_arp(ifp, &pkt);
  } else if (pkt.eth->type == mg_htons(0x86dd)) {
    pkt.ip6 = (struct ip6 *) (pkt.eth + 1);
    if (pkt.raw.len < sizeof(*pkt.eth) + sizeof(*pkt.ip6)) return;  // Truncated
    if ((pkt.ip6->ver >> 4) != 0x6) return;                         // Not IP
    mkpay(&pkt, pkt.ip6 + 1);
    rx_ip6(ifp, &pkt);
  } else if (pkt.eth->type == mg_htons(0x800)) {
    pkt.ip = (struct ip *) (pkt.eth + 1);
    if (pkt.raw.len < sizeof(*pkt.eth) + sizeof(*pkt.ip)) return;  // Truncated
    // Truncate frame to what IP header tells us
    if ((size_t) mg_ntohs(pkt.ip->len) + sizeof(struct eth) < pkt.raw.len) {
      pkt.raw.len = (size_t) mg_ntohs(pkt.ip->len) + sizeof(struct eth);
    }
    if (pkt.raw.len < sizeof(*pkt.eth) + sizeof(*pkt.ip)) return;  // Truncated
    if ((pkt.ip->ver >> 4) != 4) return;                           // Not IP
    mkpay(&pkt, pkt.ip + 1);
    rx_ip(ifp, &pkt);
  } else {
    MG_DEBUG(("Unknown eth type %x", mg_htons(pkt.eth->type)));
    if (mg_log_level >= MG_LL_VERBOSE) mg_hexdump(buf, len >= 32 ? 32 : len);
  }
}

static void mg_tcpip_poll(struct mg_tcpip_if *ifp, uint64_t now) {
  struct mg_connection *c;
  bool expired_1000ms = mg_timer_expired(&ifp->timer_1000ms, 1000, now);
  ifp->now = now;

  if (expired_1000ms) {
#if MG_ENABLE_TCPIP_PRINT_DEBUG_STATS
    const char *names[] = {"down", "up", "req", "ip", "ready"};
    MG_INFO(("Status: %s, IP: %M, rx:%u, tx:%u, dr:%u, er:%u",
             names[ifp->state], mg_print_ip4, &ifp->ip, ifp->nrecv, ifp->nsent,
             ifp->ndrop, ifp->nerr));
#endif
  }
  // Handle gw ARP request timeout, order is important
  if (expired_1000ms && ifp->state == MG_TCPIP_STATE_IP) {
    ifp->state = MG_TCPIP_STATE_READY;  // keep best-effort MAC
    onstatechange(ifp);
  }
  // poll driver
  if (ifp->driver->poll) {
    bool up = ifp->driver->poll(ifp, expired_1000ms);
    // Handle physical interface up/down status
    if (expired_1000ms) {
      bool current = ifp->state != MG_TCPIP_STATE_DOWN;
      if (!up && ifp->enable_dhcp_client) ifp->ip = 0;
      if (up != current) {  // link state has changed
        ifp->state = up == false ? MG_TCPIP_STATE_DOWN
                     : ifp->enable_dhcp_client || ifp->ip == 0
                         ? MG_TCPIP_STATE_UP
                         : MG_TCPIP_STATE_IP;
        onstatechange(ifp);
      } else if (!ifp->enable_dhcp_client && ifp->state == MG_TCPIP_STATE_UP &&
                 ifp->ip) {
        ifp->state = MG_TCPIP_STATE_IP;  // ifp->fn has set an IP
        onstatechange(ifp);
      }
      if (ifp->state == MG_TCPIP_STATE_DOWN) MG_ERROR(("Network is down"));
      mg_tcpip_call(ifp, MG_TCPIP_EV_TIMER_1S, NULL);
    }
  }
  if (ifp->state == MG_TCPIP_STATE_DOWN) return;

  // DHCP RFC-2131 (4.4)
  if (ifp->enable_dhcp_client && expired_1000ms) {
    if (ifp->state == MG_TCPIP_STATE_UP) {
      tx_dhcp_discover(ifp);  // INIT (4.4.1)
    } else if (ifp->state == MG_TCPIP_STATE_READY &&
               ifp->lease_expire > 0) {  // BOUND / RENEWING / REBINDING
      if (ifp->now >= ifp->lease_expire) {
        ifp->state = MG_TCPIP_STATE_UP, ifp->ip = 0;  // expired, release IP
        onstatechange(ifp);
      } else if (ifp->now + 30UL * 60UL * 1000UL > ifp->lease_expire &&
                 ((ifp->now / 1000) % 60) == 0) {
        // hack: 30 min before deadline, try to rebind (4.3.6) every min
        tx_dhcp_request_re(ifp, (uint8_t *) broadcast, ifp->ip, 0xffffffff);
      }  // TODO(): Handle T1 (RENEWING) and T2 (REBINDING) (4.4.5)
    }
  }

  // Read data from the network
  if (ifp->driver->rx != NULL) {  // Simple polling driver, returns one frame
    size_t len =
        ifp->driver->rx(ifp->recv_queue.buf, ifp->recv_queue.size, ifp);
    if (len > 0) {
      ifp->nrecv++;
      mg_tcpip_rx(ifp, ifp->recv_queue.buf, len);
    }
  } else {  // Complex poll / Interrupt-based driver. Queues recvd frames
    char *buf;
    size_t len = mg_queue_next(&ifp->recv_queue, &buf);
    if (len > 0) {
      mg_tcpip_rx(ifp, buf, len);
      mg_queue_del(&ifp->recv_queue, len);
    }
  }

  // Process timeouts
  for (c = ifp->mgr->conns; c != NULL; c = c->next) {
    if ((c->is_udp && !c->is_arplooking) || c->is_listening || c->is_resolving)
      continue;
    struct connstate *s = (struct connstate *) (c + 1);
    uint32_t rem_ip;
    memcpy(&rem_ip, c->rem.ip, sizeof(uint32_t));
    if (ifp->now > s->timer) {
      if (s->ttype == MIP_TTYPE_ARP) {
        mg_error(c, "ARP timeout");
      } else if (c->is_udp) {
        continue;
      } else if (s->ttype == MIP_TTYPE_ACK && s->acked != s->ack) {
        MG_VERBOSE(("%lu ack %x %x", c->id, s->seq, s->ack));
        tx_tcp(ifp, s->mac, rem_ip, TH_ACK, c->loc.port, c->rem.port,
               mg_htonl(s->seq), mg_htonl(s->ack), NULL, 0);
        s->acked = s->ack;
      } else if (s->ttype == MIP_TTYPE_SYN) {
        mg_error(c, "Connection timeout");
      } else if (s->ttype == MIP_TTYPE_FIN) {
        c->is_closing = 1;
        continue;
      } else {
        if (s->tmiss++ > 2) {
          mg_error(c, "keepalive");
        } else {
          MG_VERBOSE(("%lu keepalive", c->id));
          tx_tcp(ifp, s->mac, rem_ip, TH_ACK, c->loc.port, c->rem.port,
                 mg_htonl(s->seq - 1), mg_htonl(s->ack), NULL, 0);
        }
      }

      settmout(c, MIP_TTYPE_KEEPALIVE);
    }
  }
}

// This function executes in interrupt context, thus it should copy data
// somewhere fast. Note that newlib's malloc is not thread safe, thus use
// our lock-free queue with preallocated buffer to copy data and return asap
void mg_tcpip_qwrite(void *buf, size_t len, struct mg_tcpip_if *ifp) {
  char *p;
  if (mg_queue_book(&ifp->recv_queue, &p, len) >= len) {
    memcpy(p, buf, len);
    mg_queue_add(&ifp->recv_queue, len);
    ifp->nrecv++;
  } else {
    ifp->ndrop++;
  }
}

void mg_tcpip_init(struct mg_mgr *mgr, struct mg_tcpip_if *ifp) {
  // If MAC address is not set, make a random one
  if (ifp->mac[0] == 0 && ifp->mac[1] == 0 && ifp->mac[2] == 0 &&
      ifp->mac[3] == 0 && ifp->mac[4] == 0 && ifp->mac[5] == 0) {
    ifp->mac[0] = 0x02;  // Locally administered, unicast
    mg_random(&ifp->mac[1], sizeof(ifp->mac) - 1);
    MG_INFO(("MAC not set. Generated random: %M", mg_print_mac, ifp->mac));
  }

  // Uf DHCP name is not set, use "mip"
  if (ifp->dhcp_name[0] == '\0') {
    memcpy(ifp->dhcp_name, "mip", 4);
  }
  ifp->dhcp_name[sizeof(ifp->dhcp_name) - 1] = '\0';  // Just in case

  if (ifp->driver->init && !ifp->driver->init(ifp)) {
    MG_ERROR(("driver init failed"));
  } else {
    size_t framesize = 1540;
    ifp->tx.buf = (char *) calloc(1, framesize), ifp->tx.len = framesize;
    if (ifp->recv_queue.size == 0)
      ifp->recv_queue.size = ifp->driver->rx ? framesize : 8192;
    ifp->recv_queue.buf = (char *) calloc(1, ifp->recv_queue.size);
    ifp->timer_1000ms = mg_millis();
    mgr->ifp = ifp;
    ifp->mgr = mgr;
    ifp->mtu = MG_TCPIP_MTU_DEFAULT;
    mgr->extraconnsize = sizeof(struct connstate);
    if (ifp->ip == 0) ifp->enable_dhcp_client = true;
    memset(ifp->gwmac, 255, sizeof(ifp->gwmac));  // Set best-effort to bcast
    mg_random(&ifp->eport, sizeof(ifp->eport));   // Random from 0 to 65535
    ifp->eport |= MG_EPHEMERAL_PORT_BASE;         // Random from
                                           // MG_EPHEMERAL_PORT_BASE to 65535
    if (ifp->tx.buf == NULL || ifp->recv_queue.buf == NULL) MG_ERROR(("OOM"));
  }
}

void mg_tcpip_free(struct mg_tcpip_if *ifp) {
  free(ifp->recv_queue.buf);
  free(ifp->tx.buf);
}

static void send_syn(struct mg_connection *c) {
  struct connstate *s = (struct connstate *) (c + 1);
  uint32_t isn = mg_htonl((uint32_t) mg_ntohs(c->loc.port));
  uint32_t rem_ip;
  memcpy(&rem_ip, c->rem.ip, sizeof(uint32_t));
  tx_tcp(c->mgr->ifp, s->mac, rem_ip, TH_SYN, c->loc.port, c->rem.port, isn, 0,
         NULL, 0);
}

static void mac_resolved(struct mg_connection *c) {
  if (c->is_udp) {
    c->is_connecting = 0;
    mg_call(c, MG_EV_CONNECT, NULL);
  } else {
    send_syn(c);
    settmout(c, MIP_TTYPE_SYN);
  }
}

void mg_connect_resolved(struct mg_connection *c) {
  struct mg_tcpip_if *ifp = c->mgr->ifp;
  uint32_t rem_ip;
  memcpy(&rem_ip, c->rem.ip, sizeof(uint32_t));
  c->is_resolving = 0;
  if (ifp->eport < MG_EPHEMERAL_PORT_BASE) ifp->eport = MG_EPHEMERAL_PORT_BASE;
  memcpy(c->loc.ip, &ifp->ip, sizeof(uint32_t));
  c->loc.port = mg_htons(ifp->eport++);
  MG_DEBUG(("%lu %M -> %M", c->id, mg_print_ip_port, &c->loc, mg_print_ip_port,
            &c->rem));
  mg_call(c, MG_EV_RESOLVE, NULL);
  c->is_connecting = 1;
  if (c->is_udp && (rem_ip == 0xffffffff || rem_ip == (ifp->ip | ~ifp->mask))) {
    struct connstate *s = (struct connstate *) (c + 1);
    memset(s->mac, 0xFF, sizeof(s->mac));  // global or local broadcast
    mac_resolved(c);
  } else if (ifp->ip && ((rem_ip & ifp->mask) == (ifp->ip & ifp->mask)) &&
             rem_ip != ifp->gw) {  // skip if gw (onstatechange -> READY -> ARP)
    // If we're in the same LAN, fire an ARP lookup.
    MG_DEBUG(("%lu ARP lookup...", c->id));
    mg_tcpip_arp_request(ifp, rem_ip, NULL);
    settmout(c, MIP_TTYPE_ARP);
    c->is_arplooking = 1;
  } else if ((*((uint8_t *) &rem_ip) & 0xE0) == 0xE0) {
    struct connstate *s = (struct connstate *) (c + 1);  // 224 to 239, E0 to EF
    uint8_t mcastp[3] = {0x01, 0x00, 0x5E};              // multicast group
    memcpy(s->mac, mcastp, 3);
    memcpy(s->mac + 3, ((uint8_t *) &rem_ip) + 1, 3);  // 23 LSb
    s->mac[3] &= 0x7F;
    mac_resolved(c);
  } else {
    struct connstate *s = (struct connstate *) (c + 1);
    memcpy(s->mac, ifp->gwmac, sizeof(ifp->gwmac));
    mac_resolved(c);
  }
}

bool mg_open_listener(struct mg_connection *c, const char *url) {
  c->loc.port = mg_htons(mg_url_port(url));
  return true;
}

static void write_conn(struct mg_connection *c) {
  long len = c->is_tls ? mg_tls_send(c, c->send.buf, c->send.len)
                       : mg_io_send(c, c->send.buf, c->send.len);
  if (len == MG_IO_ERR) {
    mg_error(c, "tx err");
  } else if (len > 0) {
    mg_iobuf_del(&c->send, 0, (size_t) len);
    mg_call(c, MG_EV_WRITE, &len);
  }
}

static void init_closure(struct mg_connection *c) {
  struct connstate *s = (struct connstate *) (c + 1);
  if (c->is_udp == false && c->is_listening == false &&
      c->is_connecting == false) {  // For TCP conns,
    uint32_t rem_ip;
    memcpy(&rem_ip, c->rem.ip, sizeof(uint32_t));
    tx_tcp(c->mgr->ifp, s->mac, rem_ip, TH_FIN | TH_ACK, c->loc.port,
           c->rem.port, mg_htonl(s->seq), mg_htonl(s->ack), NULL, 0);
    settmout(c, MIP_TTYPE_FIN);
  }
}

static void close_conn(struct mg_connection *c) {
  struct connstate *s = (struct connstate *) (c + 1);
  mg_iobuf_free(&s->raw);  // For TLS connections, release raw data
  mg_close_conn(c);
}

static bool can_write(struct mg_connection *c) {
  return c->is_connecting == 0 && c->is_resolving == 0 && c->send.len > 0 &&
         c->is_tls_hs == 0 && c->is_arplooking == 0;
}

void mg_mgr_poll(struct mg_mgr *mgr, int ms) {
  struct mg_connection *c, *tmp;
  uint64_t now = mg_millis();
  mg_timer_poll(&mgr->timers, now);
  if (mgr->ifp == NULL || mgr->ifp->driver == NULL) return;
  mg_tcpip_poll(mgr->ifp, now);
  for (c = mgr->conns; c != NULL; c = tmp) {
    tmp = c->next;
    struct connstate *s = (struct connstate *) (c + 1);
    mg_call(c, MG_EV_POLL, &now);
    MG_VERBOSE(("%lu .. %c%c%c%c%c %lu %lu", c->id, c->is_tls ? 'T' : 't',
                c->is_connecting ? 'C' : 'c', c->is_tls_hs ? 'H' : 'h',
                c->is_resolving ? 'R' : 'r', c->is_closing ? 'C' : 'c',
                mg_tls_pending(c), c->rtls.len));
    // order is important, TLS conn close with > 1 record in buffer (below)
    if (c->is_tls && (c->rtls.len > 0 || mg_tls_pending(c) > 0))
      handle_tls_recv(c);
    if (can_write(c)) write_conn(c);
    if (c->is_draining && c->send.len == 0 && s->ttype != MIP_TTYPE_FIN)
      init_closure(c);
    // For non-TLS, close immediately upon completing the 3-way closure
    // For TLS, handle any pending data (above) until MIP_TTYPE_FIN expires
    if (s->twclosure &&
        (!c->is_tls || (c->rtls.len == 0 && mg_tls_pending(c) == 0)))
      c->is_closing = 1;
    if (c->is_closing) close_conn(c);
  }
  (void) ms;
}

bool mg_send(struct mg_connection *c, const void *buf, size_t len) {
  struct mg_tcpip_if *ifp = c->mgr->ifp;
  bool res = false;
  uint32_t rem_ip;
  memcpy(&rem_ip, c->rem.ip, sizeof(uint32_t));
  if (ifp->ip == 0 || ifp->state != MG_TCPIP_STATE_READY) {
    mg_error(c, "net down");
  } else if (c->is_udp && (c->is_arplooking || c->is_resolving)) {
    // Fail to send, no target MAC or IP
    MG_VERBOSE(("still resolving..."));
  } else if (c->is_udp) {
    struct connstate *s = (struct connstate *) (c + 1);
    len = trim_len(c, len);  // Trimming length if necessary
    tx_udp(ifp, s->mac, ifp->ip, c->loc.port, rem_ip, c->rem.port, buf, len);
    res = true;
  } else {
    res = mg_iobuf_add(&c->send, c->send.len, buf, len);
  }
  return res;
}
#endif  // MG_ENABLE_TCPIP

#ifdef MG_ENABLE_LINES
#line 1 "src/ota_ch32v307.c"
#endif




#if MG_OTA == MG_OTA_CH32V307
// RM: https://www.wch-ic.com/downloads/CH32FV2x_V3xRM_PDF.html

static bool mg_ch32v307_write(void *, const void *, size_t);
static bool mg_ch32v307_swap(void);

static struct mg_flash s_mg_flash_ch32v307 = {
    (void *) 0x08000000,  // Start
    480 * 1024,           // Size, first 320k is 0-wait
    4 * 1024,             // Sector size, 4k
    4,                    // Align, 32 bit
    mg_ch32v307_write,
    mg_ch32v307_swap,
};

#define FLASH_BASE 0x40022000
#define FLASH_ACTLR (FLASH_BASE + 0)
#define FLASH_KEYR (FLASH_BASE + 4)
#define FLASH_OBKEYR (FLASH_BASE + 8)
#define FLASH_STATR (FLASH_BASE + 12)
#define FLASH_CTLR (FLASH_BASE + 16)
#define FLASH_ADDR (FLASH_BASE + 20)
#define FLASH_OBR (FLASH_BASE + 28)
#define FLASH_WPR (FLASH_BASE + 32)

MG_IRAM static void flash_unlock(void) {
  static bool unlocked;
  if (unlocked == false) {
    MG_REG(FLASH_KEYR) = 0x45670123;
    MG_REG(FLASH_KEYR) = 0xcdef89ab;
    unlocked = true;
  }
}

MG_IRAM static void flash_wait(void) {
  while (MG_REG(FLASH_STATR) & MG_BIT(0)) (void) 0;
}

MG_IRAM static void mg_ch32v307_erase(void *addr) {
  // MG_INFO(("%p", addr));
  flash_unlock();
  flash_wait();
  MG_REG(FLASH_ADDR) = (uint32_t) addr;
  MG_REG(FLASH_CTLR) |= MG_BIT(1) | MG_BIT(6);  // PER | STRT;
  flash_wait();
}

MG_IRAM static bool is_page_boundary(const void *addr) {
  uint32_t val = (uint32_t) addr;
  return (val & (s_mg_flash_ch32v307.secsz - 1)) == 0;
}

MG_IRAM static bool mg_ch32v307_write(void *addr, const void *buf, size_t len) {
  // MG_INFO(("%p %p %lu", addr, buf, len));
  // mg_hexdump(buf, len);
  flash_unlock();
  const uint16_t *src = (uint16_t *) buf, *end = &src[len / 2];
  uint16_t *dst = (uint16_t *) addr;
  MG_REG(FLASH_CTLR) |= MG_BIT(0);  // Set PG
  // MG_INFO(("CTLR: %#lx", MG_REG(FLASH_CTLR)));
  while (src < end) {
    if (is_page_boundary(dst)) mg_ch32v307_erase(dst);
    *dst++ = *src++;
    flash_wait();
  }
  MG_REG(FLASH_CTLR) &= ~MG_BIT(0);  // Clear PG
  return true;
}

MG_IRAM bool mg_ch32v307_swap(void) {
  return true;
}

// just overwrite instead of swap
MG_IRAM static void single_bank_swap(char *p1, char *p2, size_t s, size_t ss) {
  // no stdlib calls here
  for (size_t ofs = 0; ofs < s; ofs += ss) {
    mg_ch32v307_write(p1 + ofs, p2 + ofs, ss);
  }
  *((volatile uint32_t *) 0xbeef0000) |= 1U << 7;  // NVIC_SystemReset()
}

bool mg_ota_begin(size_t new_firmware_size) {
  return mg_ota_flash_begin(new_firmware_size, &s_mg_flash_ch32v307);
}

bool mg_ota_write(const void *buf, size_t len) {
  return mg_ota_flash_write(buf, len, &s_mg_flash_ch32v307);
}

bool mg_ota_end(void) {
  if (mg_ota_flash_end(&s_mg_flash_ch32v307)) {
    // Swap partitions. Pray power does not go away
    MG_INFO(("Swapping partitions, size %u (%u sectors)",
             s_mg_flash_ch32v307.size,
             s_mg_flash_ch32v307.size / s_mg_flash_ch32v307.secsz));
    MG_INFO(("Do NOT power off..."));
    mg_log_level = MG_LL_NONE;
    // TODO() disable IRQ, s_flash_irq_disabled = true;
    // Runs in RAM, will reset when finished
    single_bank_swap(
        (char *) s_mg_flash_ch32v307.start,
        (char *) s_mg_flash_ch32v307.start + s_mg_flash_ch32v307.size / 2,
        s_mg_flash_ch32v307.size / 2, s_mg_flash_ch32v307.secsz);
  }
  return false;
}
#endif

#ifdef MG_ENABLE_LINES
#line 1 "src/ota_dummy.c"
#endif



#if MG_OTA == MG_OTA_NONE
bool mg_ota_begin(size_t new_firmware_size) {
  (void) new_firmware_size;
  return true;
}
bool mg_ota_write(const void *buf, size_t len) {
  (void) buf, (void) len;
  return true;
}
bool mg_ota_end(void) {
  return true;
}
#endif

#ifdef MG_ENABLE_LINES
#line 1 "src/ota_esp32.c"
#endif


#if MG_ARCH == MG_ARCH_ESP32 && MG_OTA == MG_OTA_ESP32

static const esp_partition_t *s_ota_update_partition;
static esp_ota_handle_t s_ota_update_handle;
static bool s_ota_success;

// Those empty macros do nothing, but mark places in the code which could
// potentially trigger a watchdog reboot due to the log flash erase operation
#define disable_wdt()
#define enable_wdt()

bool mg_ota_begin(size_t new_firmware_size) {
  if (s_ota_update_partition != NULL) {
    MG_ERROR(("Update in progress. Call mg_ota_end() ?"));
    return false;
  } else {
    s_ota_success = false;
    disable_wdt();
    s_ota_update_partition = esp_ota_get_next_update_partition(NULL);
    esp_err_t err = esp_ota_begin(s_ota_update_partition, new_firmware_size,
                                  &s_ota_update_handle);
    enable_wdt();
    MG_DEBUG(("esp_ota_begin(): %d", err));
    s_ota_success = (err == ESP_OK);
  }
  return s_ota_success;
}

bool mg_ota_write(const void *buf, size_t len) {
  disable_wdt();
  esp_err_t err = esp_ota_write(s_ota_update_handle, buf, len);
  enable_wdt();
  MG_INFO(("esp_ota_write(): %d", err));
  s_ota_success = err == ESP_OK;
  return s_ota_success;
}

bool mg_ota_end(void) {
  esp_err_t err = esp_ota_end(s_ota_update_handle);
  MG_DEBUG(("esp_ota_end(%p): %d", s_ota_update_handle, err));
  if (s_ota_success && err == ESP_OK) {
    err = esp_ota_set_boot_partition(s_ota_update_partition);
    s_ota_success = (err == ESP_OK);
  }
  MG_DEBUG(("Finished ESP32 OTA, success: %d", s_ota_success));
  s_ota_update_partition = NULL;
  return s_ota_success;
}

#endif

#ifdef MG_ENABLE_LINES
#line 1 "src/ota_imxrt.c"
#endif




#if MG_OTA >= MG_OTA_RT1020 && MG_OTA <= MG_OTA_RT1170

static bool mg_imxrt_write(void *, const void *, size_t);
static bool mg_imxrt_swap(void);

#if MG_OTA <= MG_OTA_RT1060
#define MG_IMXRT_FLASH_START 0x60000000
#define FLEXSPI_NOR_INSTANCE 0
#elif MG_OTA == MG_OTA_RT1064
#define MG_IMXRT_FLASH_START 0x70000000
#define FLEXSPI_NOR_INSTANCE 1
#else  // RT1170
#define MG_IMXRT_FLASH_START 0x30000000
#define FLEXSPI_NOR_INSTANCE 1
#endif

#if MG_OTA == MG_OTA_RT1050
#define MG_IMXRT_SECTOR_SIZE (256 * 1024)
#define MG_IMXRT_PAGE_SIZE 512
#else
#define MG_IMXRT_SECTOR_SIZE (4 * 1024)
#define MG_IMXRT_PAGE_SIZE 256
#endif

// TODO(): fill at init, support more devices in a dynamic way
// TODO(): then, check alignment is <= 256, see Wizard's #251
static struct mg_flash s_mg_flash_imxrt = {
    (void *) MG_IMXRT_FLASH_START,  // Start,
    4 * 1024 * 1024,                // Size, 4mb
    MG_IMXRT_SECTOR_SIZE,           // Sector size
    MG_IMXRT_PAGE_SIZE,             // Align
    mg_imxrt_write,
    mg_imxrt_swap,
};

struct mg_flexspi_lut_seq {
  uint8_t seqNum;
  uint8_t seqId;
  uint16_t reserved;
};

struct mg_flexspi_mem_config {
  uint32_t tag;
  uint32_t version;
  uint32_t reserved0;
  uint8_t readSampleClkSrc;
  uint8_t csHoldTime;
  uint8_t csSetupTime;
  uint8_t columnAddressWidth;
  uint8_t deviceModeCfgEnable;
  uint8_t deviceModeType;
  uint16_t waitTimeCfgCommands;
  struct mg_flexspi_lut_seq deviceModeSeq;
  uint32_t deviceModeArg;
  uint8_t configCmdEnable;
  uint8_t configModeType[3];
  struct mg_flexspi_lut_seq configCmdSeqs[3];
  uint32_t reserved1;
  uint32_t configCmdArgs[3];
  uint32_t reserved2;
  uint32_t controllerMiscOption;
  uint8_t deviceType;
  uint8_t sflashPadType;
  uint8_t serialClkFreq;
  uint8_t lutCustomSeqEnable;
  uint32_t reserved3[2];
  uint32_t sflashA1Size;
  uint32_t sflashA2Size;
  uint32_t sflashB1Size;
  uint32_t sflashB2Size;
  uint32_t csPadSettingOverride;
  uint32_t sclkPadSettingOverride;
  uint32_t dataPadSettingOverride;
  uint32_t dqsPadSettingOverride;
  uint32_t timeoutInMs;
  uint32_t commandInterval;
  uint16_t dataValidTime[2];
  uint16_t busyOffset;
  uint16_t busyBitPolarity;
  uint32_t lookupTable[64];
  struct mg_flexspi_lut_seq lutCustomSeq[12];
  uint32_t reserved4[4];
};

struct mg_flexspi_nor_config {
  struct mg_flexspi_mem_config memConfig;
  uint32_t pageSize;
  uint32_t sectorSize;
  uint8_t ipcmdSerialClkFreq;
  uint8_t isUniformBlockSize;
  uint8_t reserved0[2];
  uint8_t serialNorType;
  uint8_t needExitNoCmdMode;
  uint8_t halfClkForNonReadCmd;
  uint8_t needRestoreNoCmdMode;
  uint32_t blockSize;
  uint32_t reserve2[11];
};

/* FLEXSPI memory config block related defintions */
#define MG_FLEXSPI_CFG_BLK_TAG (0x42464346UL)      // ascii "FCFB" Big Endian
#define MG_FLEXSPI_CFG_BLK_VERSION (0x56010400UL)  // V1.4.0

#define MG_FLEXSPI_LUT_SEQ(cmd0, pad0, op0, cmd1, pad1, op1)       \
  (MG_FLEXSPI_LUT_OPERAND0(op0) | MG_FLEXSPI_LUT_NUM_PADS0(pad0) | \
   MG_FLEXSPI_LUT_OPCODE0(cmd0) | MG_FLEXSPI_LUT_OPERAND1(op1) |   \
   MG_FLEXSPI_LUT_NUM_PADS1(pad1) | MG_FLEXSPI_LUT_OPCODE1(cmd1))

#define MG_CMD_SDR 0x01
#define MG_CMD_DDR 0x21
#define MG_DUMMY_SDR 0x0C
#define MG_DUMMY_DDR 0x2C
#define MG_DUMMY_RWDS_DDR 0x2D
#define MG_RADDR_SDR 0x02
#define MG_RADDR_DDR 0x22
#define MG_CADDR_DDR 0x23
#define MG_READ_SDR 0x09
#define MG_READ_DDR 0x29
#define MG_WRITE_SDR 0x08
#define MG_WRITE_DDR 0x28
#define MG_STOP 0

#define MG_FLEXSPI_1PAD 0
#define MG_FLEXSPI_2PAD 1
#define MG_FLEXSPI_4PAD 2
#define MG_FLEXSPI_8PAD 3

#define MG_FLEXSPI_QSPI_LUT                                                    \
  {                                                                            \
    [0] = MG_FLEXSPI_LUT_SEQ(MG_CMD_SDR, MG_FLEXSPI_1PAD, 0xEB, MG_RADDR_SDR,  \
                             MG_FLEXSPI_4PAD, 0x18),                           \
    [1] = MG_FLEXSPI_LUT_SEQ(MG_DUMMY_SDR, MG_FLEXSPI_4PAD, 0x06, MG_READ_SDR, \
                             MG_FLEXSPI_4PAD, 0x04),                           \
    [4 * 1 + 0] = MG_FLEXSPI_LUT_SEQ(MG_CMD_SDR, MG_FLEXSPI_1PAD, 0x05,        \
                                     MG_READ_SDR, MG_FLEXSPI_1PAD, 0x04),      \
    [4 * 3 + 0] = MG_FLEXSPI_LUT_SEQ(MG_CMD_SDR, MG_FLEXSPI_1PAD, 0x06,        \
                                     MG_STOP, MG_FLEXSPI_1PAD, 0x0),           \
    [4 * 5 + 0] = MG_FLEXSPI_LUT_SEQ(MG_CMD_SDR, MG_FLEXSPI_1PAD, 0x20,        \
                                     MG_RADDR_SDR, MG_FLEXSPI_1PAD, 0x18),     \
    [4 * 8 + 0] = MG_FLEXSPI_LUT_SEQ(MG_CMD_SDR, MG_FLEXSPI_1PAD, 0xD8,        \
                                     MG_RADDR_SDR, MG_FLEXSPI_1PAD, 0x18),     \
    [4 * 9 + 0] = MG_FLEXSPI_LUT_SEQ(MG_CMD_SDR, MG_FLEXSPI_1PAD, 0x02,        \
                                     MG_RADDR_SDR, MG_FLEXSPI_1PAD, 0x18),     \
    [4 * 9 + 1] = MG_FLEXSPI_LUT_SEQ(MG_WRITE_SDR, MG_FLEXSPI_1PAD, 0x04,      \
                                     MG_STOP, MG_FLEXSPI_1PAD, 0x0),           \
    [4 * 11 + 0] = MG_FLEXSPI_LUT_SEQ(MG_CMD_SDR, MG_FLEXSPI_1PAD, 0x60,       \
                                      MG_STOP, MG_FLEXSPI_1PAD, 0x0),          \
  }

#define MG_FLEXSPI_HYPER_LUT                                                  \
  {                                                                           \
    [0] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0xA0, MG_RADDR_DDR, \
                             MG_FLEXSPI_8PAD, 0x18),                          \
    [1] = MG_FLEXSPI_LUT_SEQ(MG_CADDR_DDR, MG_FLEXSPI_8PAD, 0x10,             \
                             MG_DUMMY_DDR, MG_FLEXSPI_8PAD, 0x0C),            \
    [2] = MG_FLEXSPI_LUT_SEQ(MG_READ_DDR, MG_FLEXSPI_8PAD, 0x04, MG_STOP,     \
                             MG_FLEXSPI_1PAD, 0x0),                           \
    [4 * 1 + 0] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,        \
                                     MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0),       \
    [4 * 1 + 1] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,        \
                                     MG_CMD_DDR, MG_FLEXSPI_8PAD, 0xAA),      \
    [4 * 1 + 2] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,        \
                                     MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x05),      \
    [4 * 1 + 3] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,        \
                                     MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x70),      \
    [4 * 2 + 0] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0xA0,       \
                                     MG_RADDR_DDR, MG_FLEXSPI_8PAD, 0x18),    \
    [4 * 2 + 1] =                                                             \
        MG_FLEXSPI_LUT_SEQ(MG_CADDR_DDR, MG_FLEXSPI_8PAD, 0x10,               \
                           MG_DUMMY_RWDS_DDR, MG_FLEXSPI_8PAD, 0x0B),         \
    [4 * 2 + 2] = MG_FLEXSPI_LUT_SEQ(MG_READ_DDR, MG_FLEXSPI_8PAD, 0x4,       \
                                     MG_STOP, MG_FLEXSPI_1PAD, 0x0),          \
    [4 * 3 + 0] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,        \
                                     MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0),       \
    [4 * 3 + 1] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,        \
                                     MG_CMD_DDR, MG_FLEXSPI_8PAD, 0xAA),      \
    [4 * 3 + 2] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,        \
                                     MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x05),      \
    [4 * 3 + 3] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,        \
                                     MG_CMD_DDR, MG_FLEXSPI_8PAD, 0xAA),      \
    [4 * 4 + 0] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,        \
                                     MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0),       \
    [4 * 4 + 1] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,        \
                                     MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x55),      \
    [4 * 4 + 2] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,        \
                                     MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x02),      \
    [4 * 4 + 3] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,        \
                                     MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x55),      \
    [4 * 5 + 0] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,        \
                                     MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0),       \
    [4 * 5 + 1] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,        \
                                     MG_CMD_DDR, MG_FLEXSPI_8PAD, 0xAA),      \
    [4 * 5 + 2] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,        \
                                     MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x05),      \
    [4 * 5 + 3] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,        \
                                     MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x80),      \
    [4 * 6 + 0] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,        \
                                     MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0),       \
    [4 * 6 + 1] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,        \
                                     MG_CMD_DDR, MG_FLEXSPI_8PAD, 0xAA),      \
    [4 * 6 + 2] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,        \
                                     MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x05),      \
    [4 * 6 + 3] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,        \
                                     MG_CMD_DDR, MG_FLEXSPI_8PAD, 0xAA),      \
    [4 * 7 + 0] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,        \
                                     MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0),       \
    [4 * 7 + 1] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,        \
                                     MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x55),      \
    [4 * 7 + 2] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,        \
                                     MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x02),      \
    [4 * 7 + 3] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,        \
                                     MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x55),      \
    [4 * 8 + 0] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,        \
                                     MG_RADDR_DDR, MG_FLEXSPI_8PAD, 0x18),    \
    [4 * 8 + 1] = MG_FLEXSPI_LUT_SEQ(MG_CADDR_DDR, MG_FLEXSPI_8PAD, 0x10,     \
                                     MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0),       \
    [4 * 8 + 2] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x30,       \
                                     MG_STOP, MG_FLEXSPI_1PAD, 0x0),          \
    [4 * 9 + 0] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,        \
                                     MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0),       \
    [4 * 9 + 1] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,        \
                                     MG_CMD_DDR, MG_FLEXSPI_8PAD, 0xAA),      \
    [4 * 9 + 2] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,        \
                                     MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x05),      \
    [4 * 9 + 3] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,        \
                                     MG_CMD_DDR, MG_FLEXSPI_8PAD, 0xA0),      \
    [4 * 10 + 0] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,       \
                                      MG_RADDR_DDR, MG_FLEXSPI_8PAD, 0x18),   \
    [4 * 10 + 1] = MG_FLEXSPI_LUT_SEQ(MG_CADDR_DDR, MG_FLEXSPI_8PAD, 0x10,    \
                                      MG_WRITE_DDR, MG_FLEXSPI_8PAD, 0x80),   \
    [4 * 11 + 0] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,       \
                                      MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0),      \
    [4 * 11 + 1] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,       \
                                      MG_CMD_DDR, MG_FLEXSPI_8PAD, 0xAA),     \
    [4 * 11 + 2] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,       \
                                      MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x05),     \
    [4 * 11 + 3] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,       \
                                      MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x80),     \
    [4 * 12 + 0] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,       \
                                      MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0),      \
    [4 * 12 + 1] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,       \
                                      MG_CMD_DDR, MG_FLEXSPI_8PAD, 0xAA),     \
    [4 * 12 + 2] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,       \
                                      MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x05),     \
    [4 * 12 + 3] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,       \
                                      MG_CMD_DDR, MG_FLEXSPI_8PAD, 0xAA),     \
    [4 * 13 + 0] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,       \
                                      MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0),      \
    [4 * 13 + 1] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,       \
                                      MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x55),     \
    [4 * 13 + 2] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,       \
                                      MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x02),     \
    [4 * 13 + 3] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,       \
                                      MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x55),     \
    [4 * 14 + 0] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,       \
                                      MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0),      \
    [4 * 14 + 1] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,       \
                                      MG_CMD_DDR, MG_FLEXSPI_8PAD, 0xAA),     \
    [4 * 14 + 2] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,       \
                                      MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x05),     \
    [4 * 14 + 3] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,       \
                                      MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x10),     \
  }

#define MG_LUT_CUSTOM_SEQ                          \
  {                                                \
    {.seqNum = 0, .seqId = 0, .reserved = 0},      \
        {.seqNum = 2, .seqId = 1, .reserved = 0},  \
        {.seqNum = 2, .seqId = 3, .reserved = 0},  \
        {.seqNum = 4, .seqId = 5, .reserved = 0},  \
        {.seqNum = 2, .seqId = 9, .reserved = 0},  \
        {.seqNum = 4, .seqId = 11, .reserved = 0}, \
  }

#define MG_FLEXSPI_LUT_OPERAND0(x) (((uint32_t) (((uint32_t) (x)))) & 0xFFU)
#define MG_FLEXSPI_LUT_NUM_PADS0(x) \
  (((uint32_t) (((uint32_t) (x)) << 8U)) & 0x300U)
#define MG_FLEXSPI_LUT_OPCODE0(x) \
  (((uint32_t) (((uint32_t) (x)) << 10U)) & 0xFC00U)
#define MG_FLEXSPI_LUT_OPERAND1(x) \
  (((uint32_t) (((uint32_t) (x)) << 16U)) & 0xFF0000U)
#define MG_FLEXSPI_LUT_NUM_PADS1(x) \
  (((uint32_t) (((uint32_t) (x)) << 24U)) & 0x3000000U)
#define MG_FLEXSPI_LUT_OPCODE1(x) \
  (((uint32_t) (((uint32_t) (x)) << 26U)) & 0xFC000000U)

#if MG_OTA == MG_OTA_RT1020 || MG_OTA == MG_OTA_RT1050
// RT102X and RT105x boards support ROM API version 1.4
struct mg_flexspi_nor_driver_interface {
  uint32_t version;
  int (*init)(uint32_t instance, struct mg_flexspi_nor_config *config);
  int (*program)(uint32_t instance, struct mg_flexspi_nor_config *config,
                 uint32_t dst_addr, const uint32_t *src);
  uint32_t reserved;
  int (*erase)(uint32_t instance, struct mg_flexspi_nor_config *config,
               uint32_t start, uint32_t lengthInBytes);
  uint32_t reserved2;
  int (*update_lut)(uint32_t instance, uint32_t seqIndex,
                    const uint32_t *lutBase, uint32_t seqNumber);
  int (*xfer)(uint32_t instance, char *xfer);
  void (*clear_cache)(uint32_t instance);
};
#elif MG_OTA <= MG_OTA_RT1064
// RT104x and RT106x support ROM API version 1.5
struct mg_flexspi_nor_driver_interface {
  uint32_t version;
  int (*init)(uint32_t instance, struct mg_flexspi_nor_config *config);
  int (*program)(uint32_t instance, struct mg_flexspi_nor_config *config,
                 uint32_t dst_addr, const uint32_t *src);
  int (*erase_all)(uint32_t instance, struct mg_flexspi_nor_config *config);
  int (*erase)(uint32_t instance, struct mg_flexspi_nor_config *config,
               uint32_t start, uint32_t lengthInBytes);
  int (*read)(uint32_t instance, struct mg_flexspi_nor_config *config,
              uint32_t *dst, uint32_t addr, uint32_t lengthInBytes);
  void (*clear_cache)(uint32_t instance);
  int (*xfer)(uint32_t instance, char *xfer);
  int (*update_lut)(uint32_t instance, uint32_t seqIndex,
                    const uint32_t *lutBase, uint32_t seqNumber);
  int (*get_config)(uint32_t instance, struct mg_flexspi_nor_config *config,
                    uint32_t *option);
};
#else
// RT117x support ROM API version 1.7
struct mg_flexspi_nor_driver_interface {
  uint32_t version;
  int (*init)(uint32_t instance, struct mg_flexspi_nor_config *config);
  int (*program)(uint32_t instance, struct mg_flexspi_nor_config *config,
                 uint32_t dst_addr, const uint32_t *src);
  int (*erase_all)(uint32_t instance, struct mg_flexspi_nor_config *config);
  int (*erase)(uint32_t instance, struct mg_flexspi_nor_config *config,
               uint32_t start, uint32_t lengthInBytes);
  int (*read)(uint32_t instance, struct mg_flexspi_nor_config *config,
              uint32_t *dst, uint32_t addr, uint32_t lengthInBytes);
  uint32_t reserved;
  int (*xfer)(uint32_t instance, char *xfer);
  int (*update_lut)(uint32_t instance, uint32_t seqIndex,
                    const uint32_t *lutBase, uint32_t seqNumber);
  int (*get_config)(uint32_t instance, struct mg_flexspi_nor_config *config,
                    uint32_t *option);
  int (*erase_sector)(uint32_t instance, struct mg_flexspi_nor_config *config,
                      uint32_t address);
  int (*erase_block)(uint32_t instance, struct mg_flexspi_nor_config *config,
                     uint32_t address);
  void (*hw_reset)(uint32_t instance, uint32_t resetLogic);
  int (*wait_busy)(uint32_t instance, struct mg_flexspi_nor_config *config,
                   bool isParallelMode, uint32_t address);
  int (*set_clock_source)(uint32_t instance, uint32_t clockSrc);
  void (*config_clock)(uint32_t instance, uint32_t freqOption,
                       uint32_t sampleClkMode);
};
#endif

#if MG_OTA <= MG_OTA_RT1064
#define MG_FLEXSPI_BASE 0x402A8000
#define flexspi_nor                                                          \
  (*((struct mg_flexspi_nor_driver_interface **) (*(uint32_t *) 0x0020001c + \
                                                  16)))
#else
#define MG_FLEXSPI_BASE 0x400CC000
#define flexspi_nor                                                          \
  (*((struct mg_flexspi_nor_driver_interface **) (*(uint32_t *) 0x0021001c + \
                                                  12)))
#endif

static bool s_flash_irq_disabled;

MG_IRAM static bool flash_page_start(volatile uint32_t *dst) {
  char *base = (char *) s_mg_flash_imxrt.start,
       *end = base + s_mg_flash_imxrt.size;
  volatile char *p = (char *) dst;
  return p >= base && p < end && ((p - base) % s_mg_flash_imxrt.secsz) == 0;
}

#if MG_OTA == MG_OTA_RT1050
// Configuration for Hyper flash memory
static struct mg_flexspi_nor_config default_config = {
    .memConfig =
        {
            .tag = MG_FLEXSPI_CFG_BLK_TAG,
            .version = MG_FLEXSPI_CFG_BLK_VERSION,
            .readSampleClkSrc = 3,  // ReadSampleClk_LoopbackFromDqsPad
            .csHoldTime = 3,
            .csSetupTime = 3,
            .columnAddressWidth = 3u,
            .controllerMiscOption =
                MG_BIT(6) | MG_BIT(4) | MG_BIT(3) | MG_BIT(0),
            .deviceType = 1,  // serial NOR
            .sflashPadType = 8,
            .serialClkFreq = 7,  // 133MHz
            .sflashA1Size = 64 * 1024 * 1024,
            .dataValidTime = {15, 0},
            .busyOffset = 15,
            .busyBitPolarity = 1,
            .lutCustomSeqEnable = 0x1,
            .lookupTable = MG_FLEXSPI_HYPER_LUT,
            .lutCustomSeq = MG_LUT_CUSTOM_SEQ,
        },
    .pageSize = 512,
    .sectorSize = 256 * 1024,
    .ipcmdSerialClkFreq = 1,
    .serialNorType = 1u,
    .blockSize = 256 * 1024,
    .isUniformBlockSize = true};
#else
// Note: this QSPI configuration works for RTs supporting QSPI
// Configuration for QSPI memory
static struct mg_flexspi_nor_config default_config = {
    .memConfig = {.tag = MG_FLEXSPI_CFG_BLK_TAG,
                  .version = MG_FLEXSPI_CFG_BLK_VERSION,
                  .readSampleClkSrc = 1,  // ReadSampleClk_LoopbackFromDqsPad
                  .csHoldTime = 3,
                  .csSetupTime = 3,
                  .controllerMiscOption = MG_BIT(4),
                  .deviceType = 1,  // serial NOR
                  .sflashPadType = 4,
                  .serialClkFreq = 7,  // 133MHz
                  .sflashA1Size = 8 * 1024 * 1024,
                  .lookupTable = MG_FLEXSPI_QSPI_LUT},
    .pageSize = 256,
    .sectorSize = 4 * 1024,
    .ipcmdSerialClkFreq = 1,
    .blockSize = 64 * 1024,
    .isUniformBlockSize = false};
#endif

// must reside in RAM, as flash will be erased
MG_IRAM static int flexspi_nor_get_config(
    struct mg_flexspi_nor_config **config) {
  *config = &default_config;
  return 0;
}

#if 0
// ROM API get_config call (ROM version >= 1.5)
MG_IRAM static int flexspi_nor_get_config(
    struct mg_flexspi_nor_config **config) {
  uint32_t options[] = {0xc0000000, 0x00};

  MG_ARM_DISABLE_IRQ();
  uint32_t status =
      flexspi_nor->get_config(FLEXSPI_NOR_INSTANCE, *config, options);
  if (!s_flash_irq_disabled) {
    MG_ARM_ENABLE_IRQ();
  }
  if (status) {
    MG_ERROR(("Failed to extract flash configuration: status %u", status));
  }
  return status;
}
#endif

MG_IRAM static void mg_spin(volatile uint32_t count) {
  while (count--) (void) 0;
}

MG_IRAM static void flash_wait(void) {
  while ((*((volatile uint32_t *) (MG_FLEXSPI_BASE + 0xE0)) & MG_BIT(1)) == 0)
    mg_spin(1);
}

MG_IRAM static bool flash_erase(struct mg_flexspi_nor_config *config,
                                void *addr) {
  if (flash_page_start(addr) == false) {
    MG_ERROR(("%p is not on a sector boundary", addr));
    return false;
  }

  void *dst = (void *) ((char *) addr - (char *) s_mg_flash_imxrt.start);

  bool ok = (flexspi_nor->erase(FLEXSPI_NOR_INSTANCE, config, (uint32_t) dst,
                                s_mg_flash_imxrt.secsz) == 0);
  MG_DEBUG(("Sector starting at %p erasure: %s", addr, ok ? "ok" : "fail"));
  return ok;
}

#if 0
// standalone erase call
MG_IRAM static bool mg_imxrt_erase(void *addr) {
  struct mg_flexspi_nor_config config, *config_ptr = &config;
  bool ret;
  // Interrupts must be disabled before calls to ROM API in RT1020 and 1060
  MG_ARM_DISABLE_IRQ();
  ret = (flexspi_nor_get_config(&config_ptr) == 0);
  if (ret) ret = flash_erase(config_ptr, addr);
  MG_ARM_ENABLE_IRQ();
  return ret;
}
#endif

MG_IRAM bool mg_imxrt_swap(void) {
  return true;
}

MG_IRAM static bool mg_imxrt_write(void *addr, const void *buf, size_t len) {
  struct mg_flexspi_nor_config config, *config_ptr = &config;
  bool ok = false;
  // Interrupts must be disabled before calls to ROM API in RT1020 and 1060
  MG_ARM_DISABLE_IRQ();
  if (flexspi_nor_get_config(&config_ptr) != 0) goto fwxit;
  if ((len % s_mg_flash_imxrt.align) != 0) {
    MG_ERROR(("%lu is not aligned to %lu", len, s_mg_flash_imxrt.align));
    goto fwxit;
  }
  if ((char *) addr < (char *) s_mg_flash_imxrt.start) {
    MG_ERROR(("Invalid flash write address: %p", addr));
    goto fwxit;
  }

  uint32_t *dst = (uint32_t *) addr;
  uint32_t *src = (uint32_t *) buf;
  uint32_t *end = (uint32_t *) ((char *) buf + len);
  ok = true;

  while (ok && src < end) {
    if (flash_page_start(dst) && flash_erase(config_ptr, dst) == false) {
      ok = false;
      break;
    }
    uint32_t status;
    uint32_t dst_ofs = (uint32_t) dst - (uint32_t) s_mg_flash_imxrt.start;
    if ((char *) buf >= (char *) s_mg_flash_imxrt.start) {
      // If we copy from FLASH to FLASH, then we first need to copy the source
      // to RAM
      size_t tmp_buf_size = s_mg_flash_imxrt.align / sizeof(uint32_t);
      uint32_t tmp[tmp_buf_size];

      for (size_t i = 0; i < tmp_buf_size; i++) {
        flash_wait();
        tmp[i] = src[i];
      }
      status = flexspi_nor->program(FLEXSPI_NOR_INSTANCE, config_ptr,
                                    (uint32_t) dst_ofs, tmp);
    } else {
      status = flexspi_nor->program(FLEXSPI_NOR_INSTANCE, config_ptr,
                                    (uint32_t) dst_ofs, src);
    }
    src = (uint32_t *) ((char *) src + s_mg_flash_imxrt.align);
    dst = (uint32_t *) ((char *) dst + s_mg_flash_imxrt.align);
    if (status != 0) {
      ok = false;
    }
  }
  MG_DEBUG(("Flash write %lu bytes @ %p: %s.", len, dst, ok ? "ok" : "fail"));
fwxit:
  if (!s_flash_irq_disabled) MG_ARM_ENABLE_IRQ();
  return ok;
}

// just overwrite instead of swap
MG_IRAM static void single_bank_swap(char *p1, char *p2, size_t s, size_t ss) {
  // no stdlib calls here
  for (size_t ofs = 0; ofs < s; ofs += ss) {
    mg_imxrt_write(p1 + ofs, p2 + ofs, ss);
  }
  *(volatile unsigned long *) 0xe000ed0c = 0x5fa0004;
}

bool mg_ota_begin(size_t new_firmware_size) {
  return mg_ota_flash_begin(new_firmware_size, &s_mg_flash_imxrt);
}

bool mg_ota_write(const void *buf, size_t len) {
  return mg_ota_flash_write(buf, len, &s_mg_flash_imxrt);
}

bool mg_ota_end(void) {
  if (mg_ota_flash_end(&s_mg_flash_imxrt)) {
    if (0) {  // is_dualbank()
      // TODO(): no devices so far
      *(volatile unsigned long *) 0xe000ed0c = 0x5fa0004;
    } else {
      // Swap partitions. Pray power does not go away
      MG_INFO(("Swapping partitions, size %u (%u sectors)",
               s_mg_flash_imxrt.size,
               s_mg_flash_imxrt.size / s_mg_flash_imxrt.secsz));
      MG_INFO(("Do NOT power off..."));
      mg_log_level = MG_LL_NONE;
      s_flash_irq_disabled = true;
      // Runs in RAM, will reset when finished
      single_bank_swap(
          (char *) s_mg_flash_imxrt.start,
          (char *) s_mg_flash_imxrt.start + s_mg_flash_imxrt.size / 2,
          s_mg_flash_imxrt.size / 2, s_mg_flash_imxrt.secsz);
    }
  }
  return false;
}

#endif

#ifdef MG_ENABLE_LINES
#line 1 "src/ota_mcxn.c"
#endif




#if MG_OTA == MG_OTA_MCXN

// - Flash phrase: 16 bytes; smallest portion programmed in one operation.
// - Flash page: 128 bytes; largest portion programmed in one operation.
// - Flash sector: 8 KB; smallest portion that can be erased in one operation.
// - Flash API mg_flash_driver->program: "start" and "len" must be page-size
// aligned; to use 'phrase', FMU register access is needed. Using ROM

static bool mg_mcxn_write(void *, const void *, size_t);
static bool mg_mcxn_swap(void);

static struct mg_flash s_mg_flash_mcxn = {
    (void *) 0,  // Start, filled at init
    0,           // Size, filled at init
    0,           // Sector size, filled at init
    0,           // Align, filled at init
    mg_mcxn_write,
    mg_mcxn_swap,
};

struct mg_flash_config {
  uint32_t addr;
  uint32_t size;
  uint32_t blocks;
  uint32_t page_size;
  uint32_t sector_size;
  uint32_t ffr[6];
  uint32_t reserved0[5];
  uint32_t *bootctx;
  bool useahb;
};

struct mg_flash_driver_interface {
  uint32_t version;
  uint32_t (*init)(struct mg_flash_config *);
  uint32_t (*erase)(struct mg_flash_config *, uint32_t start, uint32_t len,
                    uint32_t key);
  uint32_t (*program)(struct mg_flash_config *, uint32_t start, uint8_t *src,
                      uint32_t len);
  uint32_t (*verify_erase)(struct mg_flash_config *, uint32_t start,
                           uint32_t len);
  uint32_t (*verify_program)(struct mg_flash_config *, uint32_t start,
                             uint32_t len, const uint8_t *expected,
                             uint32_t *addr, uint32_t *failed);
  uint32_t reserved1[12];
  uint32_t (*read)(struct mg_flash_config *, uint32_t start, uint8_t *dest,
                   uint32_t len);
  uint32_t reserved2[4];
  uint32_t (*deinit)(struct mg_flash_config *);
};
#define mg_flash_driver \
  ((struct mg_flash_driver_interface *) (*((uint32_t *) 0x1303fc00 + 4)))
#define MG_MCXN_FLASK_KEY (('k' << 24) | ('e' << 16) | ('f' << 8) | 'l')

MG_IRAM static bool flash_sector_start(volatile uint32_t *dst) {
  char *base = (char *) s_mg_flash_mcxn.start,
       *end = base + s_mg_flash_mcxn.size;
  volatile char *p = (char *) dst;
  return p >= base && p < end && ((p - base) % s_mg_flash_mcxn.secsz) == 0;
}

MG_IRAM static bool flash_erase(struct mg_flash_config *config, void *addr) {
  if (flash_sector_start(addr) == false) {
    MG_ERROR(("%p is not on a sector boundary", addr));
    return false;
  }
  uint32_t dst =
      (uint32_t) addr - (uint32_t) s_mg_flash_mcxn.start;  // future-proof
  uint32_t status = mg_flash_driver->erase(config, dst, s_mg_flash_mcxn.secsz,
                                           MG_MCXN_FLASK_KEY);
  bool ok = (status == 0);
  if (!ok) MG_ERROR(("Flash write error: %lu", status));
  MG_DEBUG(("Sector starting at %p erasure: %s", addr, ok ? "ok" : "fail"));
  return ok;
}

#if 0
// read-while-write, no need to disable IRQs for standalone usage
MG_IRAM static bool mg_mcxn_erase(void *addr) {
  uint32_t status;
  struct mg_flash_config config;
  if ((status = mg_flash_driver->init(&config)) != 0) {
    MG_ERROR(("Flash driver init error: %lu", status));
    return false;
  }
  bool ok = flash_erase(&config, addr);
  mg_flash_driver->deinit(&config);
  return ok;
}
#endif

MG_IRAM static bool mg_mcxn_swap(void) {
  // TODO(): no devices so far
  return true;
}

static bool s_flash_irq_disabled;

MG_IRAM static bool mg_mcxn_write(void *addr, const void *buf, size_t len) {
  bool ok = false;
  uint32_t status;
  struct mg_flash_config config;
  if ((status = mg_flash_driver->init(&config)) != 0) {
    MG_ERROR(("Flash driver init error: %lu", status));
    return false;
  }
  if ((len % s_mg_flash_mcxn.align) != 0) {
    MG_ERROR(("%lu is not aligned to %lu", len, s_mg_flash_mcxn.align));
    goto fwxit;
  }
  if ((((size_t) addr - (size_t) s_mg_flash_mcxn.start) %
       s_mg_flash_mcxn.align) != 0) {
    MG_ERROR(("%p is not on a page boundary", addr));
    goto fwxit;
  }

  uint32_t *dst = (uint32_t *) addr;
  uint32_t *src = (uint32_t *) buf;
  uint32_t *end = (uint32_t *) ((char *) buf + len);
  ok = true;

  MG_ARM_DISABLE_IRQ();
  while (ok && src < end) {
    if (flash_sector_start(dst) && flash_erase(&config, dst) == false) {
      ok = false;
      break;
    }
    uint32_t dst_ofs = (uint32_t) dst - (uint32_t) s_mg_flash_mcxn.start;
    // assume source is in RAM or in a different bank or read-while-write
    status = mg_flash_driver->program(&config, dst_ofs, (uint8_t *) src,
                                      s_mg_flash_mcxn.align);
    src = (uint32_t *) ((char *) src + s_mg_flash_mcxn.align);
    dst = (uint32_t *) ((char *) dst + s_mg_flash_mcxn.align);
    if (status != 0) {
      MG_ERROR(("Flash write error: %lu", status));
      ok = false;
    }
  }
  if (!s_flash_irq_disabled) MG_ARM_ENABLE_IRQ();
  MG_DEBUG(("Flash write %lu bytes @ %p: %s.", len, dst, ok ? "ok" : "fail"));

fwxit:
  mg_flash_driver->deinit(&config);
  return ok;
}

// try to swap (honor dual image), otherwise just overwrite
MG_IRAM static void single_bank_swap(char *p1, char *p2, size_t s, size_t ss) {
  char *tmp = malloc(ss);
  // no stdlib calls here
  for (size_t ofs = 0; ofs < s; ofs += ss) {
    if (tmp != NULL)
      for (size_t i = 0; i < ss; i++) tmp[i] = p1[ofs + i];
    mg_mcxn_write(p1 + ofs, p2 + ofs, ss);
    if (tmp != NULL) mg_mcxn_write(p2 + ofs, tmp, ss);
  }
  *(volatile unsigned long *) 0xe000ed0c = 0x5fa0004;
}

bool mg_ota_begin(size_t new_firmware_size) {
  uint32_t status;
  struct mg_flash_config config;
  if ((status = mg_flash_driver->init(&config)) != 0) {
    MG_ERROR(("Flash driver init error: %lu", status));
    return false;
  }
  s_mg_flash_mcxn.start = (void *) config.addr;
  s_mg_flash_mcxn.size = config.size;
  s_mg_flash_mcxn.secsz = config.sector_size;
  s_mg_flash_mcxn.align = config.page_size;
  mg_flash_driver->deinit(&config);
  MG_DEBUG(
      ("%lu-byte flash @%p, using %lu-byte sectors with %lu-byte-aligned pages",
       s_mg_flash_mcxn.size, s_mg_flash_mcxn.start, s_mg_flash_mcxn.secsz,
       s_mg_flash_mcxn.align));
  return mg_ota_flash_begin(new_firmware_size, &s_mg_flash_mcxn);
}

bool mg_ota_write(const void *buf, size_t len) {
  return mg_ota_flash_write(buf, len, &s_mg_flash_mcxn);
}

bool mg_ota_end(void) {
  if (mg_ota_flash_end(&s_mg_flash_mcxn)) {
    if (0) {  // is_dualbank()
      // TODO(): no devices so far
      *(volatile unsigned long *) 0xe000ed0c = 0x5fa0004;
    } else {
      // Swap partitions. Pray power does not go away
      MG_INFO(("Swapping partitions, size %u (%u sectors)",
               s_mg_flash_mcxn.size,
               s_mg_flash_mcxn.size / s_mg_flash_mcxn.secsz));
      MG_INFO(("Do NOT power off..."));
      mg_log_level = MG_LL_NONE;
      s_flash_irq_disabled = true;
      // Runs in RAM, will reset when finished
      single_bank_swap(
          (char *) s_mg_flash_mcxn.start,
          (char *) s_mg_flash_mcxn.start + s_mg_flash_mcxn.size / 2,
          s_mg_flash_mcxn.size / 2, s_mg_flash_mcxn.secsz);
    }
  }
  return false;
}
#endif

#ifdef MG_ENABLE_LINES
#line 1 "src/ota_picosdk.c"
#endif




#if MG_OTA == MG_OTA_PICOSDK

// Both RP2040 and RP2350 have no flash, low-level flash access support in
// bootrom, and high-level support in Pico-SDK (2.0+ for the RP2350)
// - The RP2350 in RISC-V mode is not tested
// NOTE(): See OTA design notes

static bool mg_picosdk_write(void *, const void *, size_t);
static bool mg_picosdk_swap(void);

static struct mg_flash s_mg_flash_picosdk = {
    (void *) 0x10000000,  // Start; functions handle offset
#ifdef PICO_FLASH_SIZE_BYTES
    PICO_FLASH_SIZE_BYTES,  // Size, from board definitions
#else
    0x200000,  // Size, guess... is 2M enough ?
#endif
    FLASH_SECTOR_SIZE,  // Sector size, from hardware_flash
    FLASH_PAGE_SIZE,    // Align, from hardware_flash
    mg_picosdk_write,      mg_picosdk_swap,
};

#define MG_MODULO2(x, m) ((x) & ((m) -1))

static bool __no_inline_not_in_flash_func(flash_sector_start)(
    volatile uint32_t *dst) {
  char *base = (char *) s_mg_flash_picosdk.start,
       *end = base + s_mg_flash_picosdk.size;
  volatile char *p = (char *) dst;
  return p >= base && p < end &&
         MG_MODULO2(p - base, s_mg_flash_picosdk.secsz) == 0;
}

static bool __no_inline_not_in_flash_func(flash_erase)(void *addr) {
  if (flash_sector_start(addr) == false) {
    MG_ERROR(("%p is not on a sector boundary", addr));
    return false;
  }
  void *dst = (void *) ((char *) addr - (char *) s_mg_flash_picosdk.start);
  flash_range_erase((uint32_t) dst, s_mg_flash_picosdk.secsz);
  MG_DEBUG(("Sector starting at %p erasure", addr));
  return true;
}

static bool __no_inline_not_in_flash_func(mg_picosdk_swap)(void) {
  // TODO(): RP2350 might have some A/B functionality (DS 5.1)
  return true;
}

static bool s_flash_irq_disabled;

static bool __no_inline_not_in_flash_func(mg_picosdk_write)(void *addr,
                                                            const void *buf,
                                                            size_t len) {
  if ((len % s_mg_flash_picosdk.align) != 0) {
    MG_ERROR(("%lu is not aligned to %lu", len, s_mg_flash_picosdk.align));
    return false;
  }
  if ((((size_t) addr - (size_t) s_mg_flash_picosdk.start) %
       s_mg_flash_picosdk.align) != 0) {
    MG_ERROR(("%p is not on a page boundary", addr));
    return false;
  }

  uint32_t *dst = (uint32_t *) addr;
  uint32_t *src = (uint32_t *) buf;
  uint32_t *end = (uint32_t *) ((char *) buf + len);

#ifndef __riscv
  MG_ARM_DISABLE_IRQ();
#else
  asm volatile("csrrc zero, mstatus, %0" : : "i"(1 << 3) : "memory");
#endif
  while (src < end) {
    uint32_t dst_ofs = (uint32_t) dst - (uint32_t) s_mg_flash_picosdk.start;
    if (flash_sector_start(dst) && flash_erase(dst) == false) break;
    // flash_range_program() runs in RAM and handles writing up to
    // FLASH_PAGE_SIZE bytes. Source must not be in flash
    flash_range_program((uint32_t) dst_ofs, (uint8_t *) src,
                        s_mg_flash_picosdk.align);
    src = (uint32_t *) ((char *) src + s_mg_flash_picosdk.align);
    dst = (uint32_t *) ((char *) dst + s_mg_flash_picosdk.align);
  }
  if (!s_flash_irq_disabled) {
#ifndef __riscv
    MG_ARM_ENABLE_IRQ();
#else
    asm volatile("csrrs mstatus, %0" : : "i"(1 << 3) : "memory");
#endif
  }
  MG_DEBUG(("Flash write %lu bytes @ %p.", len, dst));
  return true;
}

// just overwrite instead of swap
static void __no_inline_not_in_flash_func(single_bank_swap)(char *p1, char *p2,
                                                            size_t s,
                                                            size_t ss) {
  char *tmp = malloc(ss);
  if (tmp == NULL) return;
#if PICO_RP2040
  uint32_t xip[256 / sizeof(uint32_t)];
  void *dst = (void *) ((char *) p1 - (char *) s_mg_flash_picosdk.start);
  size_t count = MG_ROUND_UP(s, ss);
  // use SDK function calls to get BootROM function pointers
  rom_connect_internal_flash_fn connect = (rom_connect_internal_flash_fn) rom_func_lookup(ROM_FUNC_CONNECT_INTERNAL_FLASH);
  rom_flash_exit_xip_fn xit = (rom_flash_exit_xip_fn) rom_func_lookup(ROM_FUNC_FLASH_EXIT_XIP);
  rom_flash_range_program_fn program = (rom_flash_range_program_fn) rom_func_lookup(ROM_FUNC_FLASH_RANGE_PROGRAM);
  rom_flash_flush_cache_fn flush = (rom_flash_flush_cache_fn) rom_func_lookup(ROM_FUNC_FLASH_FLUSH_CACHE);
  // no stdlib calls here.
  MG_ARM_DISABLE_IRQ();
  // 2nd bootloader (XIP) is in flash, SDK functions copy it to RAM on entry
  for (size_t i = 0; i < 256 / sizeof(uint32_t); i++)
    xip[i] = ((uint32_t *) (s_mg_flash_picosdk.start))[i];
  flash_range_erase((uint32_t) dst, count);
  // flash has been erased, no XIP to copy. Only BootROM calls possible
  for (uint32_t ofs = 0; ofs < s; ofs += ss) {
    for (size_t i = 0; i < ss; i++) tmp[i] = p2[ofs + i];
    __compiler_memory_barrier();
    connect();
    xit();
    program((uint32_t) dst + ofs, tmp, ss);
    flush();
    ((void (*)(void))((intptr_t) xip + 1))(); // enter XIP again
  }
  *(volatile unsigned long *) 0xe000ed0c = 0x5fa0004;  // AIRCR = SYSRESETREQ
#else
  // RP2350 has BootRAM and copies second bootloader there, SDK uses that copy,
  // It might also be able to take advantage of partition swapping
  rom_reboot_fn reboot = (rom_reboot_fn) rom_func_lookup(ROM_FUNC_REBOOT);
  for (size_t ofs = 0; ofs < s; ofs += ss) {
    for (size_t i = 0; i < ss; i++) tmp[i] = p2[ofs + i];
    mg_picosdk_write(p1 + ofs, tmp, ss);
  }
  reboot(BOOT_TYPE_NORMAL | 0x100, 1, 0, 0); // 0x100: NO_RETURN_ON_SUCCESS
#endif
}

bool mg_ota_begin(size_t new_firmware_size) {
  return mg_ota_flash_begin(new_firmware_size, &s_mg_flash_picosdk);
}

bool mg_ota_write(const void *buf, size_t len) {
  return mg_ota_flash_write(buf, len, &s_mg_flash_picosdk);
}

bool mg_ota_end(void) {
  if (mg_ota_flash_end(&s_mg_flash_picosdk)) {
    // Swap partitions. Pray power does not go away
    MG_INFO(("Swapping partitions, size %u (%u sectors)",
             s_mg_flash_picosdk.size,
             s_mg_flash_picosdk.size / s_mg_flash_picosdk.secsz));
    MG_INFO(("Do NOT power off..."));
    mg_log_level = MG_LL_NONE;
    s_flash_irq_disabled = true;
    // Runs in RAM, will reset when finished or return on failure
    single_bank_swap(
        (char *) s_mg_flash_picosdk.start,
        (char *) s_mg_flash_picosdk.start + s_mg_flash_picosdk.size / 2,
        s_mg_flash_picosdk.size / 2, s_mg_flash_picosdk.secsz);
  }
  return false;
}
#endif

#ifdef MG_ENABLE_LINES
#line 1 "src/ota_stm32f.c"
#endif




#if MG_OTA == MG_OTA_STM32F

static bool mg_stm32f_write(void *, const void *, size_t);
static bool mg_stm32f_swap(void);

static struct mg_flash s_mg_flash_stm32f = {
    (void *) 0x08000000,  // Start
    0,                    // Size, FLASH_SIZE_REG
    0,                    // Irregular sector size
    32,                   // Align, 256 bit
    mg_stm32f_write,
    mg_stm32f_swap,
};

#define MG_FLASH_BASE 0x40023c00
#define MG_FLASH_KEYR 0x04
#define MG_FLASH_SR 0x0c
#define MG_FLASH_CR 0x10
#define MG_FLASH_OPTCR 0x14
#define MG_FLASH_SIZE_REG_F7 0x1FF0F442
#define MG_FLASH_SIZE_REG_F4 0x1FFF7A22

#define STM_DBGMCU_IDCODE 0xE0042000
#define STM_DEV_ID (MG_REG(STM_DBGMCU_IDCODE) & (MG_BIT(12) - 1))
#define SYSCFG_MEMRMP 0x40013800

#define MG_FLASH_SIZE_REG_LOCATION \
  ((STM_DEV_ID >= 0x449) ? MG_FLASH_SIZE_REG_F7 : MG_FLASH_SIZE_REG_F4)

static size_t flash_size(void) {
  return (MG_REG(MG_FLASH_SIZE_REG_LOCATION) & 0xFFFF) * 1024;
}

MG_IRAM static int is_dualbank(void) {
  // only F42x/F43x series (0x419) support dual bank
  return STM_DEV_ID == 0x419;
}

MG_IRAM static void flash_unlock(void) {
  static bool unlocked = false;
  if (unlocked == false) {
    MG_REG(MG_FLASH_BASE + MG_FLASH_KEYR) = 0x45670123;
    MG_REG(MG_FLASH_BASE + MG_FLASH_KEYR) = 0xcdef89ab;
    unlocked = true;
  }
}

#define MG_FLASH_CONFIG_16_64_128 1   // used by STM32F7
#define MG_FLASH_CONFIG_32_128_256 2  // used by STM32F4 and F2

MG_IRAM static bool flash_page_start(volatile uint32_t *dst) {
  char *base = (char *) s_mg_flash_stm32f.start;
  char *end = base + s_mg_flash_stm32f.size;

  if (is_dualbank() && dst >= (uint32_t *) (base + (end - base) / 2)) {
    dst = (uint32_t *) ((uint32_t) dst - (end - base) / 2);
  }

  uint32_t flash_config = MG_FLASH_CONFIG_16_64_128;
  if (STM_DEV_ID >= 0x449) {
    flash_config = MG_FLASH_CONFIG_32_128_256;
  }

  volatile char *p = (char *) dst;
  if (p >= base && p < end) {
    if (p < base + 16 * 1024 * 4 * flash_config) {
      if ((p - base) % (16 * 1024 * flash_config) == 0) return true;
    } else if (p == base + 16 * 1024 * 4 * flash_config) {
      return true;
    } else if ((p - base) % (128 * 1024 * flash_config) == 0) {
      return true;
    }
  }
  return false;
}

MG_IRAM static int flash_sector(volatile uint32_t *addr) {
  char *base = (char *) s_mg_flash_stm32f.start;
  char *end = base + s_mg_flash_stm32f.size;
  bool addr_in_bank_2 = false;
  if (is_dualbank() && addr >= (uint32_t *) (base + (end - base) / 2)) {
    addr = (uint32_t *) ((uint32_t) addr - (end - base) / 2);
    addr_in_bank_2 = true;
  }
  volatile char *p = (char *) addr;
  uint32_t flash_config = MG_FLASH_CONFIG_16_64_128;
  if (STM_DEV_ID >= 0x449) {
    flash_config = MG_FLASH_CONFIG_32_128_256;
  }
  int sector = -1;
  if (p >= base && p < end) {
    if (p < base + 16 * 1024 * 4 * flash_config) {
      sector = (p - base) / (16 * 1024 * flash_config);
    } else if (p >= base + 64 * 1024 * flash_config &&
               p < base + 128 * 1024 * flash_config) {
      sector = 4;
    } else {
      sector = (p - base) / (128 * 1024 * flash_config) + 4;
    }
  }
  if (sector == -1) return -1;
  if (addr_in_bank_2) sector += 12;  // a bank has 12 sectors
  return sector;
}

MG_IRAM static bool flash_is_err(void) {
  return MG_REG(MG_FLASH_BASE + MG_FLASH_SR) & ((MG_BIT(7) - 1) << 1);
}

MG_IRAM static void flash_wait(void) {
  while (MG_REG(MG_FLASH_BASE + MG_FLASH_SR) & (MG_BIT(16))) (void) 0;
}

MG_IRAM static void flash_clear_err(void) {
  flash_wait();                                // Wait until ready
  MG_REG(MG_FLASH_BASE + MG_FLASH_SR) = 0xf2;  // Clear all errors
}

MG_IRAM static bool mg_stm32f_erase(void *addr) {
  bool ok = false;
  if (flash_page_start(addr) == false) {
    MG_ERROR(("%p is not on a sector boundary", addr));
  } else {
    int sector = flash_sector(addr);
    if (sector < 0) return false;
    uint32_t sector_reg = sector;
    if (is_dualbank() && sector >= 12) {
      // 3.9.8 Flash control register (FLASH_CR) for F42xxx and F43xxx
      // BITS[7:3]
      sector_reg -= 12;
      sector_reg |= MG_BIT(4);
    }
    flash_unlock();
    flash_wait();
    uint32_t cr = MG_BIT(1);       // SER
    cr |= MG_BIT(16);              // STRT
    cr |= (sector_reg & 31) << 3;  // sector
    MG_REG(MG_FLASH_BASE + MG_FLASH_CR) = cr;
    ok = !flash_is_err();
    MG_DEBUG(("Erase sector %lu @ %p %s. CR %#lx SR %#lx", sector, addr,
              ok ? "ok" : "fail", MG_REG(MG_FLASH_BASE + MG_FLASH_CR),
              MG_REG(MG_FLASH_BASE + MG_FLASH_SR)));
    // After we have erased the sector, set CR flags for programming
    // 2 << 8 is word write parallelism, bit(0) is PG. RM0385, section 3.7.5
    MG_REG(MG_FLASH_BASE + MG_FLASH_CR) = MG_BIT(0) | (2 << 8);
    flash_clear_err();
  }
  return ok;
}

MG_IRAM static bool mg_stm32f_swap(void) {
  // STM32 F42x/F43x support dual bank, however, the memory mapping
  // change will not be carried through a hard reset. Therefore, we will use
  // the single bank approach for this family as well.
  return true;
}

static bool s_flash_irq_disabled;

MG_IRAM static bool mg_stm32f_write(void *addr, const void *buf, size_t len) {
  if ((len % s_mg_flash_stm32f.align) != 0) {
    MG_ERROR(("%lu is not aligned to %lu", len, s_mg_flash_stm32f.align));
    return false;
  }
  uint32_t *dst = (uint32_t *) addr;
  uint32_t *src = (uint32_t *) buf;
  uint32_t *end = (uint32_t *) ((char *) buf + len);
  bool ok = true;
  MG_ARM_DISABLE_IRQ();
  flash_unlock();
  flash_clear_err();
  MG_REG(MG_FLASH_BASE + MG_FLASH_CR) = MG_BIT(0) | MG_BIT(9);  // PG, 32-bit
  flash_wait();
  MG_DEBUG(("Writing flash @ %p, %lu bytes", addr, len));
  while (ok && src < end) {
    if (flash_page_start(dst) && mg_stm32f_erase(dst) == false) break;
    *(volatile uint32_t *) dst++ = *src++;
    MG_DSB();  // ensure flash is written with no errors
    flash_wait();
    if (flash_is_err()) ok = false;
  }
  if (!s_flash_irq_disabled) MG_ARM_ENABLE_IRQ();
  MG_DEBUG(("Flash write %lu bytes @ %p: %s. CR %#lx SR %#lx", len, dst,
            ok ? "ok" : "fail", MG_REG(MG_FLASH_BASE + MG_FLASH_CR),
            MG_REG(MG_FLASH_BASE + MG_FLASH_SR)));
  MG_REG(MG_FLASH_BASE + MG_FLASH_CR) &= ~MG_BIT(0);  // Clear programming flag
  return ok;
}

// just overwrite instead of swap
MG_IRAM void single_bank_swap(char *p1, char *p2, size_t size) {
  // no stdlib calls here
  mg_stm32f_write(p1, p2, size);
  *(volatile unsigned long *) 0xe000ed0c = 0x5fa0004;
}

bool mg_ota_begin(size_t new_firmware_size) {
  s_mg_flash_stm32f.size = flash_size();
  return mg_ota_flash_begin(new_firmware_size, &s_mg_flash_stm32f);
}

bool mg_ota_write(const void *buf, size_t len) {
  return mg_ota_flash_write(buf, len, &s_mg_flash_stm32f);
}

bool mg_ota_end(void) {
  if (mg_ota_flash_end(&s_mg_flash_stm32f)) {
    // Swap partitions. Pray power does not go away
    MG_INFO(("Swapping partitions, size %u (%u sectors)",
             s_mg_flash_stm32f.size, STM_DEV_ID == 0x449 ? 8 : 12));
    MG_INFO(("Do NOT power off..."));
    mg_log_level = MG_LL_NONE;
    s_flash_irq_disabled = true;
    char *p1 = (char *) s_mg_flash_stm32f.start;
    char *p2 = p1 + s_mg_flash_stm32f.size / 2;
    size_t size = s_mg_flash_stm32f.size / 2;
    // Runs in RAM, will reset when finished
    single_bank_swap(p1, p2, size);
  }
  return false;
}
#endif

#ifdef MG_ENABLE_LINES
#line 1 "src/ota_stm32h5.c"
#endif




#if MG_OTA == MG_OTA_STM32H5

static bool mg_stm32h5_write(void *, const void *, size_t);
static bool mg_stm32h5_swap(void);

static struct mg_flash s_mg_flash_stm32h5 = {
    (void *) 0x08000000,  // Start
    2 * 1024 * 1024,      // Size, 2Mb
    8 * 1024,             // Sector size, 8k
    16,                   // Align, 128 bit
    mg_stm32h5_write,
    mg_stm32h5_swap,
};

#define MG_FLASH_BASE 0x40022000          // Base address of the flash controller
#define FLASH_KEYR (MG_FLASH_BASE + 0x4)  // See RM0481 7.11
#define FLASH_OPTKEYR (MG_FLASH_BASE + 0xc)
#define FLASH_OPTCR (MG_FLASH_BASE + 0x1c)
#define FLASH_NSSR (MG_FLASH_BASE + 0x20)
#define FLASH_NSCR (MG_FLASH_BASE + 0x28)
#define FLASH_NSCCR (MG_FLASH_BASE + 0x30)
#define FLASH_OPTSR_CUR (MG_FLASH_BASE + 0x50)
#define FLASH_OPTSR_PRG (MG_FLASH_BASE + 0x54)

static void flash_unlock(void) {
  static bool unlocked = false;
  if (unlocked == false) {
    MG_REG(FLASH_KEYR) = 0x45670123;
    MG_REG(FLASH_KEYR) = 0Xcdef89ab;
    MG_REG(FLASH_OPTKEYR) = 0x08192a3b;
    MG_REG(FLASH_OPTKEYR) = 0x4c5d6e7f;
    unlocked = true;
  }
}

static int flash_page_start(volatile uint32_t *dst) {
  char *base = (char *) s_mg_flash_stm32h5.start,
       *end = base + s_mg_flash_stm32h5.size;
  volatile char *p = (char *) dst;
  return p >= base && p < end && ((p - base) % s_mg_flash_stm32h5.secsz) == 0;
}

static bool flash_is_err(void) {
  return MG_REG(FLASH_NSSR) & ((MG_BIT(8) - 1) << 17);  // RM0481 7.11.9
}

static void flash_wait(void) {
  while ((MG_REG(FLASH_NSSR) & MG_BIT(0)) &&
         (MG_REG(FLASH_NSSR) & MG_BIT(16)) == 0) {
    (void) 0;
  }
}

static void flash_clear_err(void) {
  flash_wait();                                    // Wait until ready
  MG_REG(FLASH_NSCCR) = ((MG_BIT(9) - 1) << 16U);  // Clear all errors
}

static bool flash_bank_is_swapped(void) {
  return MG_REG(FLASH_OPTCR) & MG_BIT(31);  // RM0481 7.11.8
}

static bool mg_stm32h5_erase(void *location) {
  bool ok = false;
  if (flash_page_start(location) == false) {
    MG_ERROR(("%p is not on a sector boundary"));
  } else {
    uintptr_t diff = (char *) location - (char *) s_mg_flash_stm32h5.start;
    uint32_t sector = diff / s_mg_flash_stm32h5.secsz;
    uint32_t saved_cr = MG_REG(FLASH_NSCR);  // Save CR value
    flash_unlock();
    flash_clear_err();
    MG_REG(FLASH_NSCR) = 0;
    if ((sector < 128 && flash_bank_is_swapped()) ||
        (sector > 127 && !flash_bank_is_swapped())) {
      MG_REG(FLASH_NSCR) |= MG_BIT(31);  // Set FLASH_CR_BKSEL
    }
    if (sector > 127) sector -= 128;
    MG_REG(FLASH_NSCR) |= MG_BIT(2) | (sector << 6);  // Erase | sector_num
    MG_REG(FLASH_NSCR) |= MG_BIT(5);                  // Start erasing
    flash_wait();
    ok = !flash_is_err();
    MG_DEBUG(("Erase sector %lu @ %p: %s. CR %#lx SR %#lx", sector, location,
              ok ? "ok" : "fail", MG_REG(FLASH_NSCR), MG_REG(FLASH_NSSR)));
    // mg_hexdump(location, 32);
    MG_REG(FLASH_NSCR) = saved_cr;  // Restore saved CR
  }
  return ok;
}

static bool mg_stm32h5_swap(void) {
  uint32_t desired = flash_bank_is_swapped() ? 0 : MG_BIT(31);
  flash_unlock();
  flash_clear_err();
  // printf("OPTSR_PRG 1 %#lx\n", FLASH->OPTSR_PRG);
  MG_SET_BITS(MG_REG(FLASH_OPTSR_PRG), MG_BIT(31), desired);
  // printf("OPTSR_PRG 2 %#lx\n", FLASH->OPTSR_PRG);
  MG_REG(FLASH_OPTCR) |= MG_BIT(1);  // OPTSTART
  while ((MG_REG(FLASH_OPTSR_CUR) & MG_BIT(31)) != desired) (void) 0;
  return true;
}

static bool mg_stm32h5_write(void *addr, const void *buf, size_t len) {
  if ((len % s_mg_flash_stm32h5.align) != 0) {
    MG_ERROR(("%lu is not aligned to %lu", len, s_mg_flash_stm32h5.align));
    return false;
  }
  uint32_t *dst = (uint32_t *) addr;
  uint32_t *src = (uint32_t *) buf;
  uint32_t *end = (uint32_t *) ((char *) buf + len);
  bool ok = true;
  MG_ARM_DISABLE_IRQ();
  flash_unlock();
  flash_clear_err();
  MG_REG(FLASH_NSCR) = MG_BIT(1);  // Set programming flag
  while (ok && src < end) {
    if (flash_page_start(dst) && mg_stm32h5_erase(dst) == false) {
      ok = false;
      break;
    }
    *(volatile uint32_t *) dst++ = *src++;
    flash_wait();
    if (flash_is_err()) ok = false;
  }
  MG_ARM_ENABLE_IRQ();
  MG_DEBUG(("Flash write %lu bytes @ %p: %s. CR %#lx SR %#lx", len, dst,
            flash_is_err() ? "fail" : "ok", MG_REG(FLASH_NSCR),
            MG_REG(FLASH_NSSR)));
  MG_REG(FLASH_NSCR) = 0;  // Clear flags
  return ok;
}

bool mg_ota_begin(size_t new_firmware_size) {
  return mg_ota_flash_begin(new_firmware_size, &s_mg_flash_stm32h5);
}

bool mg_ota_write(const void *buf, size_t len) {
  return mg_ota_flash_write(buf, len, &s_mg_flash_stm32h5);
}

// Actual bank swap is deferred until reset, it is safe to execute in flash
bool mg_ota_end(void) {
  if(!mg_ota_flash_end(&s_mg_flash_stm32h5)) return false;
  *(volatile unsigned long *) 0xe000ed0c = 0x5fa0004;
  return true;
}
#endif

#ifdef MG_ENABLE_LINES
#line 1 "src/ota_stm32h7.c"
#endif




#if MG_OTA == MG_OTA_STM32H7 || MG_OTA == MG_OTA_STM32H7_DUAL_CORE

// - H723/735 RM 4.3.3: Note: The application can simultaneously request a read
// and a write operation through the AXI interface.
//   - We only need IRAM for partition swapping in the H723, however, all
//   related functions must reside in IRAM for this to be possible.
// - Linker files for other devices won't define a .iram section so there's no
// associated penalty

static bool mg_stm32h7_write(void *, const void *, size_t);
static bool mg_stm32h7_swap(void);

static struct mg_flash s_mg_flash_stm32h7 = {
    (void *) 0x08000000,  // Start
    0,                    // Size, FLASH_SIZE_REG
    128 * 1024,           // Sector size, 128k
    32,                   // Align, 256 bit
    mg_stm32h7_write,
    mg_stm32h7_swap,
};

#define FLASH_BASE1 0x52002000  // Base address for bank1
#define FLASH_BASE2 0x52002100  // Base address for bank2
#define FLASH_KEYR 0x04         // See RM0433 4.9.2
#define FLASH_OPTKEYR 0x08
#define FLASH_OPTCR 0x18
#define FLASH_SR 0x10
#define FLASH_CR 0x0c
#define FLASH_CCR 0x14
#define FLASH_OPTSR_CUR 0x1c
#define FLASH_OPTSR_PRG 0x20
#define FLASH_SIZE_REG 0x1ff1e880

#define IS_DUALCORE() (MG_OTA == MG_OTA_STM32H7_DUAL_CORE)

MG_IRAM static bool is_dualbank(void) {
  if (IS_DUALCORE()) {
    // H745/H755 and H747/H757 are running on dual core.
    // Using only the 1st bank (mapped to CM7), in order not to interfere
    // with the 2nd bank (CM4), possibly causing CM4 to boot unexpectedly.
    return false;
  }
  return (s_mg_flash_stm32h7.size < 2 * 1024 * 1024) ? false : true;
}

MG_IRAM static void flash_unlock(void) {
  static bool unlocked = false;
  if (unlocked == false) {
    MG_REG(FLASH_BASE1 + FLASH_KEYR) = 0x45670123;
    MG_REG(FLASH_BASE1 + FLASH_KEYR) = 0xcdef89ab;
    if (is_dualbank()) {
      MG_REG(FLASH_BASE2 + FLASH_KEYR) = 0x45670123;
      MG_REG(FLASH_BASE2 + FLASH_KEYR) = 0xcdef89ab;
    }
    MG_REG(FLASH_BASE1 + FLASH_OPTKEYR) = 0x08192a3b;  // opt reg is "shared"
    MG_REG(FLASH_BASE1 + FLASH_OPTKEYR) = 0x4c5d6e7f;  // thus unlock once
    unlocked = true;
  }
}

MG_IRAM static bool flash_page_start(volatile uint32_t *dst) {
  char *base = (char *) s_mg_flash_stm32h7.start,
       *end = base + s_mg_flash_stm32h7.size;
  volatile char *p = (char *) dst;
  return p >= base && p < end && ((p - base) % s_mg_flash_stm32h7.secsz) == 0;
}

MG_IRAM static bool flash_is_err(uint32_t bank) {
  return MG_REG(bank + FLASH_SR) & ((MG_BIT(11) - 1) << 17);  // RM0433 4.9.5
}

MG_IRAM static void flash_wait(uint32_t bank) {
  while (MG_REG(bank + FLASH_SR) & (MG_BIT(0) | MG_BIT(2))) (void) 0;
}

MG_IRAM static void flash_clear_err(uint32_t bank) {
  flash_wait(bank);                                      // Wait until ready
  MG_REG(bank + FLASH_CCR) = ((MG_BIT(11) - 1) << 16U);  // Clear all errors
}

MG_IRAM static bool flash_bank_is_swapped(uint32_t bank) {
  return MG_REG(bank + FLASH_OPTCR) & MG_BIT(31);  // RM0433 4.9.7
}

// Figure out flash bank based on the address
MG_IRAM static uint32_t flash_bank(void *addr) {
  size_t ofs = (char *) addr - (char *) s_mg_flash_stm32h7.start;
  if (!is_dualbank()) return FLASH_BASE1;
  return ofs < s_mg_flash_stm32h7.size / 2 ? FLASH_BASE1 : FLASH_BASE2;
}

// read-while-write, no need to disable IRQs for standalone usage
MG_IRAM static bool mg_stm32h7_erase(void *addr) {
  bool ok = false;
  if (flash_page_start(addr) == false) {
    MG_ERROR(("%p is not on a sector boundary", addr));
  } else {
    uintptr_t diff = (char *) addr - (char *) s_mg_flash_stm32h7.start;
    uint32_t sector = diff / s_mg_flash_stm32h7.secsz;
    uint32_t bank = flash_bank(addr);
    uint32_t saved_cr = MG_REG(bank + FLASH_CR);  // Save CR value

    flash_unlock();
    if (sector > 7) sector -= 8;

    flash_clear_err(bank);
    MG_REG(bank + FLASH_CR) = MG_BIT(5);             // 32-bit write parallelism
    MG_REG(bank + FLASH_CR) |= (sector & 7U) << 8U;  // Sector to erase
    MG_REG(bank + FLASH_CR) |= MG_BIT(2);            // Sector erase bit
    MG_REG(bank + FLASH_CR) |= MG_BIT(7);            // Start erasing
    ok = !flash_is_err(bank);
    MG_DEBUG(("Erase sector %lu @ %p %s. CR %#lx SR %#lx", sector, addr,
              ok ? "ok" : "fail", MG_REG(bank + FLASH_CR),
              MG_REG(bank + FLASH_SR)));
    MG_REG(bank + FLASH_CR) = saved_cr;  // Restore CR
  }
  return ok;
}

MG_IRAM static bool mg_stm32h7_swap(void) {
  if (!is_dualbank()) return true;
  uint32_t bank = FLASH_BASE1;
  uint32_t desired = flash_bank_is_swapped(bank) ? 0 : MG_BIT(31);
  flash_unlock();
  flash_clear_err(bank);
  // printf("OPTSR_PRG 1 %#lx\n", FLASH->OPTSR_PRG);
  MG_SET_BITS(MG_REG(bank + FLASH_OPTSR_PRG), MG_BIT(31), desired);
  // printf("OPTSR_PRG 2 %#lx\n", FLASH->OPTSR_PRG);
  MG_REG(bank + FLASH_OPTCR) |= MG_BIT(1);  // OPTSTART
  while ((MG_REG(bank + FLASH_OPTSR_CUR) & MG_BIT(31)) != desired) (void) 0;
  return true;
}

static bool s_flash_irq_disabled;

MG_IRAM static bool mg_stm32h7_write(void *addr, const void *buf, size_t len) {
  if ((len % s_mg_flash_stm32h7.align) != 0) {
    MG_ERROR(("%lu is not aligned to %lu", len, s_mg_flash_stm32h7.align));
    return false;
  }
  uint32_t bank = flash_bank(addr);
  uint32_t *dst = (uint32_t *) addr;
  uint32_t *src = (uint32_t *) buf;
  uint32_t *end = (uint32_t *) ((char *) buf + len);
  bool ok = true;
  MG_ARM_DISABLE_IRQ();
  flash_unlock();
  flash_clear_err(bank);
  MG_REG(bank + FLASH_CR) = MG_BIT(1);   // Set programming flag
  MG_REG(bank + FLASH_CR) |= MG_BIT(5);  // 32-bit write parallelism
  while (ok && src < end) {
    if (flash_page_start(dst) && mg_stm32h7_erase(dst) == false) {
      ok = false;
      break;
    }
    *(volatile uint32_t *) dst++ = *src++;
    flash_wait(bank);
    if (flash_is_err(bank)) ok = false;
  }
  if (!s_flash_irq_disabled) MG_ARM_ENABLE_IRQ();
  MG_DEBUG(("Flash write %lu bytes @ %p: %s. CR %#lx SR %#lx", len, dst,
            ok ? "ok" : "fail", MG_REG(bank + FLASH_CR),
            MG_REG(bank + FLASH_SR)));
  MG_REG(bank + FLASH_CR) &= ~MG_BIT(1);  // Clear programming flag
  return ok;
}

// just overwrite instead of swap
MG_IRAM static void single_bank_swap(char *p1, char *p2, size_t s, size_t ss) {
  // no stdlib calls here
  for (size_t ofs = 0; ofs < s; ofs += ss) {
    mg_stm32h7_write(p1 + ofs, p2 + ofs, ss);
  }
  *(volatile unsigned long *) 0xe000ed0c = 0x5fa0004;
}

bool mg_ota_begin(size_t new_firmware_size) {
  s_mg_flash_stm32h7.size = MG_REG(FLASH_SIZE_REG) * 1024;
  if (IS_DUALCORE()) {
    // Using only the 1st bank (mapped to CM7)
    s_mg_flash_stm32h7.size /= 2;
  }
  return mg_ota_flash_begin(new_firmware_size, &s_mg_flash_stm32h7);
}

bool mg_ota_write(const void *buf, size_t len) {
  return mg_ota_flash_write(buf, len, &s_mg_flash_stm32h7);
}

bool mg_ota_end(void) {
  if (mg_ota_flash_end(&s_mg_flash_stm32h7)) {
    if (is_dualbank()) {
      // Bank swap is deferred until reset, been executing in flash, reset
      *(volatile unsigned long *) 0xe000ed0c = 0x5fa0004;
    } else {
      // Swap partitions. Pray power does not go away
      MG_INFO(("Swapping partitions, size %u (%u sectors)",
               s_mg_flash_stm32h7.size,
               s_mg_flash_stm32h7.size / s_mg_flash_stm32h7.secsz));
      MG_INFO(("Do NOT power off..."));
      mg_log_level = MG_LL_NONE;
      s_flash_irq_disabled = true;
      // Runs in RAM, will reset when finished
      single_bank_swap(
          (char *) s_mg_flash_stm32h7.start,
          (char *) s_mg_flash_stm32h7.start + s_mg_flash_stm32h7.size / 2,
          s_mg_flash_stm32h7.size / 2, s_mg_flash_stm32h7.secsz);
    }
  }
  return false;
}
#endif

#ifdef MG_ENABLE_LINES
#line 1 "src/printf.c"
#endif




size_t mg_queue_vprintf(struct mg_queue *q, const char *fmt, va_list *ap) {
  size_t len = mg_snprintf(NULL, 0, fmt, ap);
  char *buf;
  if (len == 0 || mg_queue_book(q, &buf, len + 1) < len + 1) {
    len = 0;  // Nah. Not enough space
  } else {
    len = mg_vsnprintf((char *) buf, len + 1, fmt, ap);
    mg_queue_add(q, len);
  }
  return len;
}

size_t mg_queue_printf(struct mg_queue *q, const char *fmt, ...) {
  va_list ap;
  size_t len;
  va_start(ap, fmt);
  len = mg_queue_vprintf(q, fmt, &ap);
  va_end(ap);
  return len;
}

static void mg_pfn_iobuf_private(char ch, void *param, bool expand) {
  struct mg_iobuf *io = (struct mg_iobuf *) param;
  if (expand && io->len + 2 > io->size) mg_iobuf_resize(io, io->len + 2);
  if (io->len + 2 <= io->size) {
    io->buf[io->len++] = (uint8_t) ch;
    io->buf[io->len] = 0;
  } else if (io->len < io->size) {
    io->buf[io->len++] = 0;  // Guarantee to 0-terminate
  }
}

static void mg_putchar_iobuf_static(char ch, void *param) {
  mg_pfn_iobuf_private(ch, param, false);
}

void mg_pfn_iobuf(char ch, void *param) {
  mg_pfn_iobuf_private(ch, param, true);
}

size_t mg_vsnprintf(char *buf, size_t len, const char *fmt, va_list *ap) {
  struct mg_iobuf io = {(uint8_t *) buf, len, 0, 0};
  size_t n = mg_vxprintf(mg_putchar_iobuf_static, &io, fmt, ap);
  if (n < len) buf[n] = '\0';
  return n;
}

size_t mg_snprintf(char *buf, size_t len, const char *fmt, ...) {
  va_list ap;
  size_t n;
  va_start(ap, fmt);
  n = mg_vsnprintf(buf, len, fmt, &ap);
  va_end(ap);
  return n;
}

char *mg_vmprintf(const char *fmt, va_list *ap) {
  struct mg_iobuf io = {0, 0, 0, 256};
  mg_vxprintf(mg_pfn_iobuf, &io, fmt, ap);
  return (char *) io.buf;
}

char *mg_mprintf(const char *fmt, ...) {
  char *s;
  va_list ap;
  va_start(ap, fmt);
  s = mg_vmprintf(fmt, &ap);
  va_end(ap);
  return s;
}

void mg_pfn_stdout(char c, void *param) {
  putchar(c);
  (void) param;
}

static size_t print_ip4(void (*out)(char, void *), void *arg, uint8_t *p) {
  return mg_xprintf(out, arg, "%d.%d.%d.%d", p[0], p[1], p[2], p[3]);
}

static size_t print_ip6(void (*out)(char, void *), void *arg, uint16_t *p) {
  return mg_xprintf(out, arg, "[%x:%x:%x:%x:%x:%x:%x:%x]", mg_ntohs(p[0]),
                    mg_ntohs(p[1]), mg_ntohs(p[2]), mg_ntohs(p[3]),
                    mg_ntohs(p[4]), mg_ntohs(p[5]), mg_ntohs(p[6]),
                    mg_ntohs(p[7]));
}

size_t mg_print_ip4(void (*out)(char, void *), void *arg, va_list *ap) {
  uint8_t *p = va_arg(*ap, uint8_t *);
  return print_ip4(out, arg, p);
}

size_t mg_print_ip6(void (*out)(char, void *), void *arg, va_list *ap) {
  uint16_t *p = va_arg(*ap, uint16_t *);
  return print_ip6(out, arg, p);
}

size_t mg_print_ip(void (*out)(char, void *), void *arg, va_list *ap) {
  struct mg_addr *addr = va_arg(*ap, struct mg_addr *);
  if (addr->is_ip6) return print_ip6(out, arg, (uint16_t *) addr->ip);
  return print_ip4(out, arg, (uint8_t *) &addr->ip);
}

size_t mg_print_ip_port(void (*out)(char, void *), void *arg, va_list *ap) {
  struct mg_addr *a = va_arg(*ap, struct mg_addr *);
  return mg_xprintf(out, arg, "%M:%hu", mg_print_ip, a, mg_ntohs(a->port));
}

size_t mg_print_mac(void (*out)(char, void *), void *arg, va_list *ap) {
  uint8_t *p = va_arg(*ap, uint8_t *);
  return mg_xprintf(out, arg, "%02x:%02x:%02x:%02x:%02x:%02x", p[0], p[1], p[2],
                    p[3], p[4], p[5]);
}

static char mg_esc(int c, bool esc) {
  const char *p, *esc1 = "\b\f\n\r\t\\\"", *esc2 = "bfnrt\\\"";
  for (p = esc ? esc1 : esc2; *p != '\0'; p++) {
    if (*p == c) return esc ? esc2[p - esc1] : esc1[p - esc2];
  }
  return 0;
}

static char mg_escape(int c) {
  return mg_esc(c, true);
}

static size_t qcpy(void (*out)(char, void *), void *ptr, char *buf,
                   size_t len) {
  size_t i = 0, extra = 0;
  for (i = 0; i < len && buf[i] != '\0'; i++) {
    char c = mg_escape(buf[i]);
    if (c) {
      out('\\', ptr), out(c, ptr), extra++;
    } else {
      out(buf[i], ptr);
    }
  }
  return i + extra;
}

static size_t bcpy(void (*out)(char, void *), void *arg, uint8_t *buf,
                   size_t len) {
  size_t i, j, n = 0;
  const char *t =
      "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
  for (i = 0; i < len; i += 3) {
    uint8_t c1 = buf[i], c2 = i + 1 < len ? buf[i + 1] : 0,
            c3 = i + 2 < len ? buf[i + 2] : 0;
    char tmp[4] = {t[c1 >> 2], t[(c1 & 3) << 4 | (c2 >> 4)], '=', '='};
    if (i + 1 < len) tmp[2] = t[(c2 & 15) << 2 | (c3 >> 6)];
    if (i + 2 < len) tmp[3] = t[c3 & 63];
    for (j = 0; j < sizeof(tmp) && tmp[j] != '\0'; j++) out(tmp[j], arg);
    n += j;
  }
  return n;
}

size_t mg_print_hex(void (*out)(char, void *), void *arg, va_list *ap) {
  size_t bl = (size_t) va_arg(*ap, int);
  uint8_t *p = va_arg(*ap, uint8_t *);
  const char *hex = "0123456789abcdef";
  size_t j;
  for (j = 0; j < bl; j++) {
    out(hex[(p[j] >> 4) & 0x0F], arg);
    out(hex[p[j] & 0x0F], arg);
  }
  return 2 * bl;
}
size_t mg_print_base64(void (*out)(char, void *), void *arg, va_list *ap) {
  size_t len = (size_t) va_arg(*ap, int);
  uint8_t *buf = va_arg(*ap, uint8_t *);
  return bcpy(out, arg, buf, len);
}

size_t mg_print_esc(void (*out)(char, void *), void *arg, va_list *ap) {
  size_t len = (size_t) va_arg(*ap, int);
  char *p = va_arg(*ap, char *);
  if (len == 0) len = p == NULL ? 0 : strlen(p);
  return qcpy(out, arg, p, len);
}

#ifdef MG_ENABLE_LINES
#line 1 "src/queue.c"
#endif



#if (defined(__GNUC__) && (__GNUC__ > 4) ||                                \
     (defined(__GNUC_MINOR__) && __GNUC__ == 4 && __GNUC_MINOR__ >= 1)) || \
    defined(__clang__)
#define MG_MEMORY_BARRIER() __sync_synchronize()
#elif defined(_MSC_VER) && _MSC_VER >= 1700
#define MG_MEMORY_BARRIER() MemoryBarrier()
#elif !defined(MG_MEMORY_BARRIER)
#define MG_MEMORY_BARRIER()
#endif

// Every message in a queue is prepended by a 32-bit message length (ML).
// If ML is 0, then it is the end, and reader must wrap to the beginning.
//
//  Queue when q->tail <= q->head:
//  |----- free -----| ML | message1 | ML | message2 |  ----- free ------|
//  ^                ^                               ^                   ^
// buf              tail                            head                len
//
//  Queue when q->tail > q->head:
//  | ML | message2 |----- free ------| ML | message1 | 0 |---- free ----|
//  ^               ^                 ^                                  ^
// buf             head              tail                               len

void mg_queue_init(struct mg_queue *q, char *buf, size_t size) {
  q->size = size;
  q->buf = buf;
  q->head = q->tail = 0;
}

static size_t mg_queue_read_len(struct mg_queue *q) {
  uint32_t n = 0;
  MG_MEMORY_BARRIER();
  memcpy(&n, q->buf + q->tail, sizeof(n));
  assert(q->tail + n + sizeof(n) <= q->size);
  return n;
}

static void mg_queue_write_len(struct mg_queue *q, size_t len) {
  uint32_t n = (uint32_t) len;
  memcpy(q->buf + q->head, &n, sizeof(n));
  MG_MEMORY_BARRIER();
}

size_t mg_queue_book(struct mg_queue *q, char **buf, size_t len) {
  size_t space = 0, hs = sizeof(uint32_t) * 2;  // *2 is for the 0 marker
  if (q->head >= q->tail && q->head + len + hs <= q->size) {
    space = q->size - q->head - hs;  // There is enough space
  } else if (q->head >= q->tail && q->tail > hs) {
    mg_queue_write_len(q, 0);  // Not enough space ahead
    q->head = 0;               // Wrap head to the beginning
  }
  if (q->head + hs + len < q->tail) space = q->tail - q->head - hs;
  if (buf != NULL) *buf = q->buf + q->head + sizeof(uint32_t);
  return space;
}

size_t mg_queue_next(struct mg_queue *q, char **buf) {
  size_t len = 0;
  if (q->tail != q->head) {
    len = mg_queue_read_len(q);
    if (len == 0) {  // Zero (head wrapped) ?
      q->tail = 0;   // Reset tail to the start
      if (q->head > q->tail) len = mg_queue_read_len(q);  // Read again
    }
  }
  if (buf != NULL) *buf = q->buf + q->tail + sizeof(uint32_t);
  assert(q->tail + len <= q->size);
  return len;
}

void mg_queue_add(struct mg_queue *q, size_t len) {
  assert(len > 0);
  mg_queue_write_len(q, len);
  assert(q->head + sizeof(uint32_t) * 2 + len <= q->size);
  q->head += len + sizeof(uint32_t);
}

void mg_queue_del(struct mg_queue *q, size_t len) {
  q->tail += len + sizeof(uint32_t);
  assert(q->tail + sizeof(uint32_t) <= q->size);
}

#ifdef MG_ENABLE_LINES
#line 1 "src/rpc.c"
#endif



void mg_rpc_add(struct mg_rpc **head, struct mg_str method,
                void (*fn)(struct mg_rpc_req *), void *fn_data) {
  struct mg_rpc *rpc = (struct mg_rpc *) calloc(1, sizeof(*rpc));
  if (rpc != NULL) {
    rpc->method = mg_strdup(method);
    rpc->fn = fn;
    rpc->fn_data = fn_data;
    rpc->next = *head, *head = rpc;
  }
}

void mg_rpc_del(struct mg_rpc **head, void (*fn)(struct mg_rpc_req *)) {
  struct mg_rpc *r;
  while ((r = *head) != NULL) {
    if (r->fn == fn || fn == NULL) {
      *head = r->next;
      free((void *) r->method.buf);
      free(r);
    } else {
      head = &(*head)->next;
    }
  }
}

static void mg_rpc_call(struct mg_rpc_req *r, struct mg_str method) {
  struct mg_rpc *h = r->head == NULL ? NULL : *r->head;
  while (h != NULL && !mg_match(method, h->method, NULL)) h = h->next;
  if (h != NULL) {
    r->rpc = h;
    h->fn(r);
  } else {
    mg_rpc_err(r, -32601, "\"%.*s not found\"", (int) method.len, method.buf);
  }
}

void mg_rpc_process(struct mg_rpc_req *r) {
  int len, off = mg_json_get(r->frame, "$.method", &len);
  if (off > 0 && r->frame.buf[off] == '"') {
    struct mg_str method = mg_str_n(&r->frame.buf[off + 1], (size_t) len - 2);
    mg_rpc_call(r, method);
  } else if ((off = mg_json_get(r->frame, "$.result", &len)) > 0 ||
             (off = mg_json_get(r->frame, "$.error", &len)) > 0) {
    mg_rpc_call(r, mg_str(""));  // JSON response! call "" method handler
  } else {
    mg_rpc_err(r, -32700, "%m", mg_print_esc, (int) r->frame.len,
               r->frame.buf);  // Invalid
  }
}

void mg_rpc_vok(struct mg_rpc_req *r, const char *fmt, va_list *ap) {
  int len, off = mg_json_get(r->frame, "$.id", &len);
  if (off > 0) {
    mg_xprintf(r->pfn, r->pfn_data, "{%m:%.*s,%m:", mg_print_esc, 0, "id", len,
               &r->frame.buf[off], mg_print_esc, 0, "result");
    mg_vxprintf(r->pfn, r->pfn_data, fmt == NULL ? "null" : fmt, ap);
    mg_xprintf(r->pfn, r->pfn_data, "}");
  }
}

void mg_rpc_ok(struct mg_rpc_req *r, const char *fmt, ...) {
  va_list ap;
  va_start(ap, fmt);
  mg_rpc_vok(r, fmt, &ap);
  va_end(ap);
}

void mg_rpc_verr(struct mg_rpc_req *r, int code, const char *fmt, va_list *ap) {
  int len, off = mg_json_get(r->frame, "$.id", &len);
  mg_xprintf(r->pfn, r->pfn_data, "{");
  if (off > 0) {
    mg_xprintf(r->pfn, r->pfn_data, "%m:%.*s,", mg_print_esc, 0, "id", len,
               &r->frame.buf[off]);
  }
  mg_xprintf(r->pfn, r->pfn_data, "%m:{%m:%d,%m:", mg_print_esc, 0, "error",
             mg_print_esc, 0, "code", code, mg_print_esc, 0, "message");
  mg_vxprintf(r->pfn, r->pfn_data, fmt == NULL ? "null" : fmt, ap);
  mg_xprintf(r->pfn, r->pfn_data, "}}");
}

void mg_rpc_err(struct mg_rpc_req *r, int code, const char *fmt, ...) {
  va_list ap;
  va_start(ap, fmt);
  mg_rpc_verr(r, code, fmt, &ap);
  va_end(ap);
}

static size_t print_methods(mg_pfn_t pfn, void *pfn_data, va_list *ap) {
  struct mg_rpc *h, **head = (struct mg_rpc **) va_arg(*ap, void **);
  size_t len = 0;
  for (h = *head; h != NULL; h = h->next) {
    if (h->method.len == 0) continue;  // Ignore response handler
    len += mg_xprintf(pfn, pfn_data, "%s%m", h == *head ? "" : ",",
                      mg_print_esc, (int) h->method.len, h->method.buf);
  }
  return len;
}

void mg_rpc_list(struct mg_rpc_req *r) {
  mg_rpc_ok(r, "[%M]", print_methods, r->head);
}

#ifdef MG_ENABLE_LINES
#line 1 "src/sha1.c"
#endif
/* Copyright(c) By Steve Reid <steve@edmweb.com> */
/* 100% Public Domain */



union char64long16 {
  unsigned char c[64];
  uint32_t l[16];
};

#define rol(value, bits) (((value) << (bits)) | ((value) >> (32 - (bits))))

static uint32_t blk0(union char64long16 *block, int i) {
  if (MG_BIG_ENDIAN) {
  } else {
    block->l[i] = (rol(block->l[i], 24) & 0xFF00FF00) |
                  (rol(block->l[i], 8) & 0x00FF00FF);
  }
  return block->l[i];
}

/* Avoid redefine warning (ARM /usr/include/sys/ucontext.h define R0~R4) */
#undef blk
#undef R0
#undef R1
#undef R2
#undef R3
#undef R4

#define blk(i)                                                               \
  (block->l[i & 15] = rol(block->l[(i + 13) & 15] ^ block->l[(i + 8) & 15] ^ \
                              block->l[(i + 2) & 15] ^ block->l[i & 15],     \
                          1))
#define R0(v, w, x, y, z, i)                                          \
  z += ((w & (x ^ y)) ^ y) + blk0(block, i) + 0x5A827999 + rol(v, 5); \
  w = rol(w, 30);
#define R1(v, w, x, y, z, i)                                  \
  z += ((w & (x ^ y)) ^ y) + blk(i) + 0x5A827999 + rol(v, 5); \
  w = rol(w, 30);
#define R2(v, w, x, y, z, i)                          \
  z += (w ^ x ^ y) + blk(i) + 0x6ED9EBA1 + rol(v, 5); \
  w = rol(w, 30);
#define R3(v, w, x, y, z, i)                                        \
  z += (((w | x) & y) | (w & x)) + blk(i) + 0x8F1BBCDC + rol(v, 5); \
  w = rol(w, 30);
#define R4(v, w, x, y, z, i)                          \
  z += (w ^ x ^ y) + blk(i) + 0xCA62C1D6 + rol(v, 5); \
  w = rol(w, 30);

static void mg_sha1_transform(uint32_t state[5],
                              const unsigned char *buffer) {
  uint32_t a, b, c, d, e;
  union char64long16 block[1];

  memcpy(block, buffer, 64);
  a = state[0];
  b = state[1];
  c = state[2];
  d = state[3];
  e = state[4];
  R0(a, b, c, d, e, 0);
  R0(e, a, b, c, d, 1);
  R0(d, e, a, b, c, 2);
  R0(c, d, e, a, b, 3);
  R0(b, c, d, e, a, 4);
  R0(a, b, c, d, e, 5);
  R0(e, a, b, c, d, 6);
  R0(d, e, a, b, c, 7);
  R0(c, d, e, a, b, 8);
  R0(b, c, d, e, a, 9);
  R0(a, b, c, d, e, 10);
  R0(e, a, b, c, d, 11);
  R0(d, e, a, b, c, 12);
  R0(c, d, e, a, b, 13);
  R0(b, c, d, e, a, 14);
  R0(a, b, c, d, e, 15);
  R1(e, a, b, c, d, 16);
  R1(d, e, a, b, c, 17);
  R1(c, d, e, a, b, 18);
  R1(b, c, d, e, a, 19);
  R2(a, b, c, d, e, 20);
  R2(e, a, b, c, d, 21);
  R2(d, e, a, b, c, 22);
  R2(c, d, e, a, b, 23);
  R2(b, c, d, e, a, 24);
  R2(a, b, c, d, e, 25);
  R2(e, a, b, c, d, 26);
  R2(d, e, a, b, c, 27);
  R2(c, d, e, a, b, 28);
  R2(b, c, d, e, a, 29);
  R2(a, b, c, d, e, 30);
  R2(e, a, b, c, d, 31);
  R2(d, e, a, b, c, 32);
  R2(c, d, e, a, b, 33);
  R2(b, c, d, e, a, 34);
  R2(a, b, c, d, e, 35);
  R2(e, a, b, c, d, 36);
  R2(d, e, a, b, c, 37);
  R2(c, d, e, a, b, 38);
  R2(b, c, d, e, a, 39);
  R3(a, b, c, d, e, 40);
  R3(e, a, b, c, d, 41);
  R3(d, e, a, b, c, 42);
  R3(c, d, e, a, b, 43);
  R3(b, c, d, e, a, 44);
  R3(a, b, c, d, e, 45);
  R3(e, a, b, c, d, 46);
  R3(d, e, a, b, c, 47);
  R3(c, d, e, a, b, 48);
  R3(b, c, d, e, a, 49);
  R3(a, b, c, d, e, 50);
  R3(e, a, b, c, d, 51);
  R3(d, e, a, b, c, 52);
  R3(c, d, e, a, b, 53);
  R3(b, c, d, e, a, 54);
  R3(a, b, c, d, e, 55);
  R3(e, a, b, c, d, 56);
  R3(d, e, a, b, c, 57);
  R3(c, d, e, a, b, 58);
  R3(b, c, d, e, a, 59);
  R4(a, b, c, d, e, 60);
  R4(e, a, b, c, d, 61);
  R4(d, e, a, b, c, 62);
  R4(c, d, e, a, b, 63);
  R4(b, c, d, e, a, 64);
  R4(a, b, c, d, e, 65);
  R4(e, a, b, c, d, 66);
  R4(d, e, a, b, c, 67);
  R4(c, d, e, a, b, 68);
  R4(b, c, d, e, a, 69);
  R4(a, b, c, d, e, 70);
  R4(e, a, b, c, d, 71);
  R4(d, e, a, b, c, 72);
  R4(c, d, e, a, b, 73);
  R4(b, c, d, e, a, 74);
  R4(a, b, c, d, e, 75);
  R4(e, a, b, c, d, 76);
  R4(d, e, a, b, c, 77);
  R4(c, d, e, a, b, 78);
  R4(b, c, d, e, a, 79);
  state[0] += a;
  state[1] += b;
  state[2] += c;
  state[3] += d;
  state[4] += e;
  /* Erase working structures. The order of operations is important,
   * used to ensure that compiler doesn't optimize those out. */
  memset(block, 0, sizeof(block));
  a = b = c = d = e = 0;
  (void) a;
  (void) b;
  (void) c;
  (void) d;
  (void) e;
}

void mg_sha1_init(mg_sha1_ctx *context) {
  context->state[0] = 0x67452301;
  context->state[1] = 0xEFCDAB89;
  context->state[2] = 0x98BADCFE;
  context->state[3] = 0x10325476;
  context->state[4] = 0xC3D2E1F0;
  context->count[0] = context->count[1] = 0;
}

void mg_sha1_update(mg_sha1_ctx *context, const unsigned char *data,
                    size_t len) {
  size_t i, j;

  j = context->count[0];
  if ((context->count[0] += (uint32_t) len << 3) < j) context->count[1]++;
  context->count[1] += (uint32_t) (len >> 29);
  j = (j >> 3) & 63;
  if ((j + len) > 63) {
    memcpy(&context->buffer[j], data, (i = 64 - j));
    mg_sha1_transform(context->state, context->buffer);
    for (; i + 63 < len; i += 64) {
      mg_sha1_transform(context->state, &data[i]);
    }
    j = 0;
  } else
    i = 0;
  memcpy(&context->buffer[j], &data[i], len - i);
}

void mg_sha1_final(unsigned char digest[20], mg_sha1_ctx *context) {
  unsigned i;
  unsigned char finalcount[8], c;

  for (i = 0; i < 8; i++) {
    finalcount[i] = (unsigned char) ((context->count[(i >= 4 ? 0 : 1)] >>
                                      ((3 - (i & 3)) * 8)) &
                                     255);
  }
  c = 0200;
  mg_sha1_update(context, &c, 1);
  while ((context->count[0] & 504) != 448) {
    c = 0000;
    mg_sha1_update(context, &c, 1);
  }
  mg_sha1_update(context, finalcount, 8);
  for (i = 0; i < 20; i++) {
    digest[i] =
        (unsigned char) ((context->state[i >> 2] >> ((3 - (i & 3)) * 8)) & 255);
  }
  memset(context, '\0', sizeof(*context));
  memset(&finalcount, '\0', sizeof(finalcount));
}

#ifdef MG_ENABLE_LINES
#line 1 "src/sha256.c"
#endif
// https://github.com/B-Con/crypto-algorithms
// Author:     Brad Conte (brad AT bradconte.com)
// Disclaimer: This code is presented "as is" without any guarantees.
// Details:    Defines the API for the corresponding SHA1 implementation.
// Copyright:  public domain



#define ror(x, n) (((x) >> (n)) | ((x) << (32 - (n))))
#define ch(x, y, z) (((x) & (y)) ^ (~(x) & (z)))
#define maj(x, y, z) (((x) & (y)) ^ ((x) & (z)) ^ ((y) & (z)))
#define ep0(x) (ror(x, 2) ^ ror(x, 13) ^ ror(x, 22))
#define ep1(x) (ror(x, 6) ^ ror(x, 11) ^ ror(x, 25))
#define sig0(x) (ror(x, 7) ^ ror(x, 18) ^ ((x) >> 3))
#define sig1(x) (ror(x, 17) ^ ror(x, 19) ^ ((x) >> 10))

static const uint32_t mg_sha256_k[64] = {
    0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5, 0x3956c25b, 0x59f111f1,
    0x923f82a4, 0xab1c5ed5, 0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3,
    0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174, 0xe49b69c1, 0xefbe4786,
    0x0fc19dc6, 0x240ca1cc, 0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da,
    0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7, 0xc6e00bf3, 0xd5a79147,
    0x06ca6351, 0x14292967, 0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13,
    0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85, 0xa2bfe8a1, 0xa81a664b,
    0xc24b8b70, 0xc76c51a3, 0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070,
    0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5, 0x391c0cb3, 0x4ed8aa4a,
    0x5b9cca4f, 0x682e6ff3, 0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208,
    0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2};

void mg_sha256_init(mg_sha256_ctx *ctx) {
  ctx->len = 0;
  ctx->bits = 0;
  ctx->state[0] = 0x6a09e667;
  ctx->state[1] = 0xbb67ae85;
  ctx->state[2] = 0x3c6ef372;
  ctx->state[3] = 0xa54ff53a;
  ctx->state[4] = 0x510e527f;
  ctx->state[5] = 0x9b05688c;
  ctx->state[6] = 0x1f83d9ab;
  ctx->state[7] = 0x5be0cd19;
}

static void mg_sha256_chunk(mg_sha256_ctx *ctx) {
  int i, j;
  uint32_t a, b, c, d, e, f, g, h;
  uint32_t m[64];
  for (i = 0, j = 0; i < 16; ++i, j += 4)
    m[i] = (uint32_t) (((uint32_t) ctx->buffer[j] << 24) |
                       ((uint32_t) ctx->buffer[j + 1] << 16) |
                       ((uint32_t) ctx->buffer[j + 2] << 8) |
                       ((uint32_t) ctx->buffer[j + 3]));
  for (; i < 64; ++i)
    m[i] = sig1(m[i - 2]) + m[i - 7] + sig0(m[i - 15]) + m[i - 16];

  a = ctx->state[0];
  b = ctx->state[1];
  c = ctx->state[2];
  d = ctx->state[3];
  e = ctx->state[4];
  f = ctx->state[5];
  g = ctx->state[6];
  h = ctx->state[7];

  for (i = 0; i < 64; ++i) {
    uint32_t t1 = h + ep1(e) + ch(e, f, g) + mg_sha256_k[i] + m[i];
    uint32_t t2 = ep0(a) + maj(a, b, c);
    h = g;
    g = f;
    f = e;
    e = d + t1;
    d = c;
    c = b;
    b = a;
    a = t1 + t2;
  }

  ctx->state[0] += a;
  ctx->state[1] += b;
  ctx->state[2] += c;
  ctx->state[3] += d;
  ctx->state[4] += e;
  ctx->state[5] += f;
  ctx->state[6] += g;
  ctx->state[7] += h;
}

void mg_sha256_update(mg_sha256_ctx *ctx, const unsigned char *data,
                      size_t len) {
  size_t i;
  for (i = 0; i < len; i++) {
    ctx->buffer[ctx->len] = data[i];
    if ((++ctx->len) == 64) {
      mg_sha256_chunk(ctx);
      ctx->bits += 512;
      ctx->len = 0;
    }
  }
}

// TODO: make final reusable (remove side effects)
void mg_sha256_final(unsigned char digest[32], mg_sha256_ctx *ctx) {
  uint32_t i = ctx->len;
  if (i < 56) {
    ctx->buffer[i++] = 0x80;
    while (i < 56) {
      ctx->buffer[i++] = 0x00;
    }
  } else {
    ctx->buffer[i++] = 0x80;
    while (i < 64) {
      ctx->buffer[i++] = 0x00;
    }
    mg_sha256_chunk(ctx);
    memset(ctx->buffer, 0, 56);
  }

  ctx->bits += ctx->len * 8;
  ctx->buffer[63] = (uint8_t) ((ctx->bits) & 0xff);
  ctx->buffer[62] = (uint8_t) ((ctx->bits >> 8) & 0xff);
  ctx->buffer[61] = (uint8_t) ((ctx->bits >> 16) & 0xff);
  ctx->buffer[60] = (uint8_t) ((ctx->bits >> 24) & 0xff);
  ctx->buffer[59] = (uint8_t) ((ctx->bits >> 32) & 0xff);
  ctx->buffer[58] = (uint8_t) ((ctx->bits >> 40) & 0xff);
  ctx->buffer[57] = (uint8_t) ((ctx->bits >> 48) & 0xff);
  ctx->buffer[56] = (uint8_t) ((ctx->bits >> 56) & 0xff);
  mg_sha256_chunk(ctx);

  for (i = 0; i < 4; ++i) {
    digest[i] = (uint8_t) ((ctx->state[0] >> (24 - i * 8)) & 0xff);
    digest[i + 4] = (uint8_t) ((ctx->state[1] >> (24 - i * 8)) & 0xff);
    digest[i + 8] = (uint8_t) ((ctx->state[2] >> (24 - i * 8)) & 0xff);
    digest[i + 12] = (uint8_t) ((ctx->state[3] >> (24 - i * 8)) & 0xff);
    digest[i + 16] = (uint8_t) ((ctx->state[4] >> (24 - i * 8)) & 0xff);
    digest[i + 20] = (uint8_t) ((ctx->state[5] >> (24 - i * 8)) & 0xff);
    digest[i + 24] = (uint8_t) ((ctx->state[6] >> (24 - i * 8)) & 0xff);
    digest[i + 28] = (uint8_t) ((ctx->state[7] >> (24 - i * 8)) & 0xff);
  }
}

void mg_sha256(uint8_t dst[32], uint8_t *data, size_t datasz) {
  mg_sha256_ctx ctx;
  mg_sha256_init(&ctx);
  mg_sha256_update(&ctx, data, datasz);
  mg_sha256_final(dst, &ctx);
}

void mg_hmac_sha256(uint8_t dst[32], uint8_t *key, size_t keysz, uint8_t *data,
                    size_t datasz) {
  mg_sha256_ctx ctx;
  uint8_t k[64] = {0};
  uint8_t o_pad[64], i_pad[64];
  unsigned int i;
  memset(i_pad, 0x36, sizeof(i_pad));
  memset(o_pad, 0x5c, sizeof(o_pad));
  if (keysz < 64) {
    if (keysz > 0) memmove(k, key, keysz);
  } else {
    mg_sha256_init(&ctx);
    mg_sha256_update(&ctx, key, keysz);
    mg_sha256_final(k, &ctx);
  }
  for (i = 0; i < sizeof(k); i++) {
    i_pad[i] ^= k[i];
    o_pad[i] ^= k[i];
  }
  mg_sha256_init(&ctx);
  mg_sha256_update(&ctx, i_pad, sizeof(i_pad));
  mg_sha256_update(&ctx, data, datasz);
  mg_sha256_final(dst, &ctx);
  mg_sha256_init(&ctx);
  mg_sha256_update(&ctx, o_pad, sizeof(o_pad));
  mg_sha256_update(&ctx, dst, 32);
  mg_sha256_final(dst, &ctx);
}

#define rotr64(x, n) (((x) >> (n)) | ((x) << (64 - (n))))
#define ep064(x) (rotr64(x, 28) ^ rotr64(x, 34) ^ rotr64(x, 39))
#define ep164(x) (rotr64(x, 14) ^ rotr64(x, 18) ^ rotr64(x, 41))
#define sig064(x) (rotr64(x, 1) ^ rotr64(x, 8) ^ ((x) >> 7))
#define sig164(x) (rotr64(x, 19) ^ rotr64(x, 61) ^ ((x) >> 6))

static const uint64_t mg_sha256_k2[80] = {
    0x428a2f98d728ae22, 0x7137449123ef65cd, 0xb5c0fbcfec4d3b2f,
    0xe9b5dba58189dbbc, 0x3956c25bf348b538, 0x59f111f1b605d019,
    0x923f82a4af194f9b, 0xab1c5ed5da6d8118, 0xd807aa98a3030242,
    0x12835b0145706fbe, 0x243185be4ee4b28c, 0x550c7dc3d5ffb4e2,
    0x72be5d74f27b896f, 0x80deb1fe3b1696b1, 0x9bdc06a725c71235,
    0xc19bf174cf692694, 0xe49b69c19ef14ad2, 0xefbe4786384f25e3,
    0x0fc19dc68b8cd5b5, 0x240ca1cc77ac9c65, 0x2de92c6f592b0275,
    0x4a7484aa6ea6e483, 0x5cb0a9dcbd41fbd4, 0x76f988da831153b5,
    0x983e5152ee66dfab, 0xa831c66d2db43210, 0xb00327c898fb213f,
    0xbf597fc7beef0ee4, 0xc6e00bf33da88fc2, 0xd5a79147930aa725,
    0x06ca6351e003826f, 0x142929670a0e6e70, 0x27b70a8546d22ffc,
    0x2e1b21385c26c926, 0x4d2c6dfc5ac42aed, 0x53380d139d95b3df,
    0x650a73548baf63de, 0x766a0abb3c77b2a8, 0x81c2c92e47edaee6,
    0x92722c851482353b, 0xa2bfe8a14cf10364, 0xa81a664bbc423001,
    0xc24b8b70d0f89791, 0xc76c51a30654be30, 0xd192e819d6ef5218,
    0xd69906245565a910, 0xf40e35855771202a, 0x106aa07032bbd1b8,
    0x19a4c116b8d2d0c8, 0x1e376c085141ab53, 0x2748774cdf8eeb99,
    0x34b0bcb5e19b48a8, 0x391c0cb3c5c95a63, 0x4ed8aa4ae3418acb,
    0x5b9cca4f7763e373, 0x682e6ff3d6b2b8a3, 0x748f82ee5defb2fc,
    0x78a5636f43172f60, 0x84c87814a1f0ab72, 0x8cc702081a6439ec,
    0x90befffa23631e28, 0xa4506cebde82bde9, 0xbef9a3f7b2c67915,
    0xc67178f2e372532b, 0xca273eceea26619c, 0xd186b8c721c0c207,
    0xeada7dd6cde0eb1e, 0xf57d4f7fee6ed178, 0x06f067aa72176fba,
    0x0a637dc5a2c898a6, 0x113f9804bef90dae, 0x1b710b35131c471b,
    0x28db77f523047d84, 0x32caab7b40c72493, 0x3c9ebe0a15c9bebc,
    0x431d67c49c100d4c, 0x4cc5d4becb3e42b6, 0x597f299cfc657e2a,
    0x5fcb6fab3ad6faec, 0x6c44198c4a475817};

static void mg_sha384_transform(mg_sha384_ctx *ctx, const uint8_t data[]) {
  uint64_t m[80];
  uint64_t a, b, c, d, e, f, g, h;
  int i, j;

  for (i = 0, j = 0; i < 16; ++i, j += 8)
    m[i] = ((uint64_t) data[j] << 56) | ((uint64_t) data[j + 1] << 48) |
           ((uint64_t) data[j + 2] << 40) | ((uint64_t) data[j + 3] << 32) |
           ((uint64_t) data[j + 4] << 24) | ((uint64_t) data[j + 5] << 16) |
           ((uint64_t) data[j + 6] << 8) | ((uint64_t) data[j + 7]);
  for (; i < 80; ++i)
    m[i] = sig164(m[i - 2]) + m[i - 7] + sig064(m[i - 15]) + m[i - 16];

  a = ctx->state[0];
  b = ctx->state[1];
  c = ctx->state[2];
  d = ctx->state[3];
  e = ctx->state[4];
  f = ctx->state[5];
  g = ctx->state[6];
  h = ctx->state[7];

  for (i = 0; i < 80; ++i) {
    uint64_t t1 = h + ep164(e) + ch(e, f, g) + mg_sha256_k2[i] + m[i];
    uint64_t t2 = ep064(a) + maj(a, b, c);
    h = g;
    g = f;
    f = e;
    e = d + t1;
    d = c;
    c = b;
    b = a;
    a = t1 + t2;
  }

  ctx->state[0] += a;
  ctx->state[1] += b;
  ctx->state[2] += c;
  ctx->state[3] += d;
  ctx->state[4] += e;
  ctx->state[5] += f;
  ctx->state[6] += g;
  ctx->state[7] += h;
}

void mg_sha384_init(mg_sha384_ctx *ctx) {
  ctx->datalen = 0;
  ctx->bitlen[0] = 0;
  ctx->bitlen[1] = 0;
  ctx->state[0] = 0xcbbb9d5dc1059ed8;
  ctx->state[1] = 0x629a292a367cd507;
  ctx->state[2] = 0x9159015a3070dd17;
  ctx->state[3] = 0x152fecd8f70e5939;
  ctx->state[4] = 0x67332667ffc00b31;
  ctx->state[5] = 0x8eb44a8768581511;
  ctx->state[6] = 0xdb0c2e0d64f98fa7;
  ctx->state[7] = 0x47b5481dbefa4fa4;
}

void mg_sha384_update(mg_sha384_ctx *ctx, const uint8_t *data, size_t len) {
  size_t i;
  for (i = 0; i < len; ++i) {
    ctx->buffer[ctx->datalen] = data[i];
    ctx->datalen++;
    if (ctx->datalen == 128) {
      mg_sha384_transform(ctx, ctx->buffer);
      ctx->bitlen[1] += 1024;
      if (ctx->bitlen[1] < 1024) ctx->bitlen[0]++;
      ctx->datalen = 0;
    }
  }
}

void mg_sha384_final(uint8_t hash[48], mg_sha384_ctx *ctx) {
  size_t i = ctx->datalen;

  if (ctx->datalen < 112) {
    ctx->buffer[i++] = 0x80;
    while (i < 112) ctx->buffer[i++] = 0x00;
  } else {
    ctx->buffer[i++] = 0x80;
    while (i < 128) ctx->buffer[i++] = 0x00;
    mg_sha384_transform(ctx, ctx->buffer);
    memset(ctx->buffer, 0, 112);
  }

  ctx->bitlen[1] += ctx->datalen * 8;
  if (ctx->bitlen[1] < ctx->datalen * 8) ctx->bitlen[0]++;
  ctx->buffer[127] = (uint8_t) (ctx->bitlen[1]);
  ctx->buffer[126] = (uint8_t) (ctx->bitlen[1] >> 8);
  ctx->buffer[125] = (uint8_t) (ctx->bitlen[1] >> 16);
  ctx->buffer[124] = (uint8_t) (ctx->bitlen[1] >> 24);
  ctx->buffer[123] = (uint8_t) (ctx->bitlen[1] >> 32);
  ctx->buffer[122] = (uint8_t) (ctx->bitlen[1] >> 40);
  ctx->buffer[121] = (uint8_t) (ctx->bitlen[1] >> 48);
  ctx->buffer[120] = (uint8_t) (ctx->bitlen[1] >> 56);
  ctx->buffer[119] = (uint8_t) (ctx->bitlen[0]);
  ctx->buffer[118] = (uint8_t) (ctx->bitlen[0] >> 8);
  ctx->buffer[117] = (uint8_t) (ctx->bitlen[0] >> 16);
  ctx->buffer[116] = (uint8_t) (ctx->bitlen[0] >> 24);
  ctx->buffer[115] = (uint8_t) (ctx->bitlen[0] >> 32);
  ctx->buffer[114] = (uint8_t) (ctx->bitlen[0] >> 40);
  ctx->buffer[113] = (uint8_t) (ctx->bitlen[0] >> 48);
  ctx->buffer[112] = (uint8_t) (ctx->bitlen[0] >> 56);
  mg_sha384_transform(ctx, ctx->buffer);

  for (i = 0; i < 6; ++i) {
    hash[i * 8] = (uint8_t) ((ctx->state[i] >> 56) & 0xff);
    hash[i * 8 + 1] = (uint8_t) ((ctx->state[i] >> 48) & 0xff);
    hash[i * 8 + 2] = (uint8_t) ((ctx->state[i] >> 40) & 0xff);
    hash[i * 8 + 3] = (uint8_t) ((ctx->state[i] >> 32) & 0xff);
    hash[i * 8 + 4] = (uint8_t) ((ctx->state[i] >> 24) & 0xff);
    hash[i * 8 + 5] = (uint8_t) ((ctx->state[i] >> 16) & 0xff);
    hash[i * 8 + 6] = (uint8_t) ((ctx->state[i] >> 8) & 0xff);
    hash[i * 8 + 7] = (uint8_t) (ctx->state[i] & 0xff);
  }
}

void mg_sha384(uint8_t dst[48], uint8_t *data, size_t datasz) {
  mg_sha384_ctx ctx;
  mg_sha384_init(&ctx);
  mg_sha384_update(&ctx, data, datasz);
  mg_sha384_final(dst, &ctx);
}

#ifdef MG_ENABLE_LINES
#line 1 "src/sntp.c"
#endif






#define SNTP_TIME_OFFSET 2208988800U  // (1970 - 1900) in seconds
#define SNTP_MAX_FRAC 4294967295.0    // 2 ** 32 - 1

static uint64_t s_boot_timestamp = 0;  // Updated by SNTP

uint64_t mg_now(void) {
  return mg_millis() + s_boot_timestamp;
}

static int64_t gettimestamp(const uint32_t *data) {
  uint32_t sec = mg_ntohl(data[0]), frac = mg_ntohl(data[1]);
  if (sec) sec -= SNTP_TIME_OFFSET;
  return ((int64_t) sec) * 1000 + (int64_t) (frac / SNTP_MAX_FRAC * 1000.0);
}

int64_t mg_sntp_parse(const unsigned char *buf, size_t len) {
  int64_t epoch_milliseconds = -1;
  int mode = len > 0 ? buf[0] & 7 : 0;
  int version = len > 0 ? (buf[0] >> 3) & 7 : 0;
  if (len < 48) {
    MG_ERROR(("%s", "corrupt packet"));
  } else if (mode != 4 && mode != 5) {
    MG_ERROR(("%s", "not a server reply"));
  } else if (buf[1] == 0) {
    MG_ERROR(("%s", "server sent a kiss of death"));
  } else if (version == 4 || version == 3) {
    // int64_t ref = gettimestamp((uint32_t *) &buf[16]);
    int64_t origin_time = gettimestamp((uint32_t *) &buf[24]);
    int64_t receive_time = gettimestamp((uint32_t *) &buf[32]);
    int64_t transmit_time = gettimestamp((uint32_t *) &buf[40]);
    int64_t now = (int64_t) mg_millis();
    int64_t latency = (now - origin_time) - (transmit_time - receive_time);
    epoch_milliseconds = transmit_time + latency / 2;
    s_boot_timestamp = (uint64_t) (epoch_milliseconds - now);
  } else {
    MG_ERROR(("unexpected version: %d", version));
  }
  return epoch_milliseconds;
}

static void sntp_cb(struct mg_connection *c, int ev, void *ev_data) {
  uint64_t *expiration_time = (uint64_t *) c->data;
  if (ev == MG_EV_OPEN) {
    *expiration_time = mg_millis() + 3000;  // Store expiration time in 3s
  } else if (ev == MG_EV_CONNECT) {
    mg_sntp_request(c);
  } else if (ev == MG_EV_READ) {
    int64_t milliseconds = mg_sntp_parse(c->recv.buf, c->recv.len);
    if (milliseconds > 0) {
      s_boot_timestamp = (uint64_t) milliseconds - mg_millis();
      mg_call(c, MG_EV_SNTP_TIME, (uint64_t *) &milliseconds);
      MG_DEBUG(("%lu got time: %lld ms from epoch", c->id, milliseconds));
    }
    // mg_iobuf_del(&c->recv, 0, c->recv.len);  // Free receive buffer
    c->is_closing = 1;
  } else if (ev == MG_EV_POLL) {
    if (mg_millis() > *expiration_time) c->is_closing = 1;
  } else if (ev == MG_EV_CLOSE) {
  }
  (void) ev_data;
}

void mg_sntp_request(struct mg_connection *c) {
  if (c->is_resolving) {
    MG_ERROR(("%lu wait until resolved", c->id));
  } else {
    int64_t now = (int64_t) mg_millis();  // Use int64_t, for vc98
    uint8_t buf[48] = {0};
    uint32_t *t = (uint32_t *) &buf[40];
    double frac = ((double) (now % 1000)) / 1000.0 * SNTP_MAX_FRAC;
    buf[0] = (0 << 6) | (4 << 3) | 3;
    t[0] = mg_htonl((uint32_t) (now / 1000) + SNTP_TIME_OFFSET);
    t[1] = mg_htonl((uint32_t) frac);
    mg_send(c, buf, sizeof(buf));
  }
}

struct mg_connection *mg_sntp_connect(struct mg_mgr *mgr, const char *url,
                                      mg_event_handler_t fn, void *fnd) {
  struct mg_connection *c = NULL;
  if (url == NULL) url = "udp://time.google.com:123";
  if ((c = mg_connect(mgr, url, fn, fnd)) != NULL) {
    c->pfn = sntp_cb;
    sntp_cb(c, MG_EV_OPEN, (void *) url);
  }
  return c;
}

#ifdef MG_ENABLE_LINES
#line 1 "src/sock.c"
#endif











#if MG_ENABLE_SOCKET

#ifndef closesocket
#define closesocket(x) close(x)
#endif

#define FD(c_) ((MG_SOCKET_TYPE) (size_t) (c_)->fd)
#define S2PTR(s_) ((void *) (size_t) (s_))

#ifndef MSG_NONBLOCKING
#define MSG_NONBLOCKING 0
#endif

#ifndef AF_INET6
#define AF_INET6 10
#endif

#ifndef MG_SOCK_ERR
#define MG_SOCK_ERR(errcode) ((errcode) < 0 ? errno : 0)
#endif

#ifndef MG_SOCK_INTR
#define MG_SOCK_INTR(fd) (fd == MG_INVALID_SOCKET && MG_SOCK_ERR(-1) == EINTR)
#endif

#ifndef MG_SOCK_PENDING
#define MG_SOCK_PENDING(errcode) \
  (((errcode) < 0) && (errno == EINPROGRESS || errno == EWOULDBLOCK))
#endif

#ifndef MG_SOCK_RESET
#define MG_SOCK_RESET(errcode) \
  (((errcode) < 0) && (errno == EPIPE || errno == ECONNRESET))
#endif

union usa {
  struct sockaddr sa;
  struct sockaddr_in sin;
#if MG_ENABLE_IPV6
  struct sockaddr_in6 sin6;
#endif
};

static socklen_t tousa(struct mg_addr *a, union usa *usa) {
  socklen_t len = sizeof(usa->sin);
  memset(usa, 0, sizeof(*usa));
  usa->sin.sin_family = AF_INET;
  usa->sin.sin_port = a->port;
  memcpy(&usa->sin.sin_addr, a->ip, sizeof(uint32_t));
#if MG_ENABLE_IPV6
  if (a->is_ip6) {
    usa->sin.sin_family = AF_INET6;
    usa->sin6.sin6_port = a->port;
    usa->sin6.sin6_scope_id = a->scope_id;
    memcpy(&usa->sin6.sin6_addr, a->ip, sizeof(a->ip));
    len = sizeof(usa->sin6);
  }
#endif
  return len;
}

static void tomgaddr(union usa *usa, struct mg_addr *a, bool is_ip6) {
  a->is_ip6 = is_ip6;
  a->port = usa->sin.sin_port;
  memcpy(&a->ip, &usa->sin.sin_addr, sizeof(uint32_t));
#if MG_ENABLE_IPV6
  if (is_ip6) {
    memcpy(a->ip, &usa->sin6.sin6_addr, sizeof(a->ip));
    a->port = usa->sin6.sin6_port;
    a->scope_id = (uint8_t) usa->sin6.sin6_scope_id;
  }
#endif
}

static void setlocaddr(MG_SOCKET_TYPE fd, struct mg_addr *addr) {
  union usa usa;
  socklen_t n = sizeof(usa);
  if (getsockname(fd, &usa.sa, &n) == 0) {
    tomgaddr(&usa, addr, n != sizeof(usa.sin));
  }
}

static void iolog(struct mg_connection *c, char *buf, long n, bool r) {
  if (n == MG_IO_WAIT) {
    // Do nothing
  } else if (n <= 0) {
    c->is_closing = 1;  // Termination. Don't call mg_error(): #1529
  } else if (n > 0) {
    if (c->is_hexdumping) {
      MG_INFO(("\n-- %lu %M %s %M %ld", c->id, mg_print_ip_port, &c->loc,
               r ? "<-" : "->", mg_print_ip_port, &c->rem, n));
      mg_hexdump(buf, (size_t) n);
    }
    if (r) {
      c->recv.len += (size_t) n;
      mg_call(c, MG_EV_READ, &n);
    } else {
      mg_iobuf_del(&c->send, 0, (size_t) n);
      // if (c->send.len == 0) mg_iobuf_resize(&c->send, 0);
      if (c->send.len == 0) {
        MG_EPOLL_MOD(c, 0);
      }
      mg_call(c, MG_EV_WRITE, &n);
    }
  }
}

long mg_io_send(struct mg_connection *c, const void *buf, size_t len) {
  long n;
  if (c->is_udp) {
    union usa usa;
    socklen_t slen = tousa(&c->rem, &usa);
    n = sendto(FD(c), (char *) buf, len, 0, &usa.sa, slen);
    if (n > 0) setlocaddr(FD(c), &c->loc);
  } else {
    n = send(FD(c), (char *) buf, len, MSG_NONBLOCKING);
  }
  MG_VERBOSE(("%lu %ld %d", c->id, n, MG_SOCK_ERR(n)));
  if (MG_SOCK_PENDING(n)) return MG_IO_WAIT;
  if (MG_SOCK_RESET(n)) return MG_IO_RESET; // MbedTLS, see #1507
  if (n <= 0) return MG_IO_ERR;
  return n;
}

bool mg_send(struct mg_connection *c, const void *buf, size_t len) {
  if (c->is_udp) {
    long n = mg_io_send(c, buf, len);
    MG_DEBUG(("%lu %ld %lu:%lu:%lu %ld err %d", c->id, c->fd, c->send.len,
              c->recv.len, c->rtls.len, n, MG_SOCK_ERR(n)));
    iolog(c, (char *) buf, n, false);
    return n > 0;
  } else {
    return mg_iobuf_add(&c->send, c->send.len, buf, len);
  }
}

static void mg_set_non_blocking_mode(MG_SOCKET_TYPE fd) {
#if defined(MG_CUSTOM_NONBLOCK)
  MG_CUSTOM_NONBLOCK(fd);
#elif MG_ARCH == MG_ARCH_WIN32 && MG_ENABLE_WINSOCK
  unsigned long on = 1;
  ioctlsocket(fd, FIONBIO, &on);
#elif MG_ENABLE_RL
  unsigned long on = 1;
  ioctlsocket(fd, FIONBIO, &on);
#elif MG_ENABLE_FREERTOS_TCP
  const BaseType_t off = 0;
  if (setsockopt(fd, 0, FREERTOS_SO_RCVTIMEO, &off, sizeof(off)) != 0) (void) 0;
  if (setsockopt(fd, 0, FREERTOS_SO_SNDTIMEO, &off, sizeof(off)) != 0) (void) 0;
#elif MG_ENABLE_LWIP
  lwip_fcntl(fd, F_SETFL, O_NONBLOCK);
#elif MG_ARCH == MG_ARCH_AZURERTOS
  fcntl(fd, F_SETFL, O_NONBLOCK);
#elif MG_ARCH == MG_ARCH_TIRTOS
  int val = 0;
  setsockopt(fd, SOL_SOCKET, SO_BLOCKING, &val, sizeof(val));
  // SPRU524J section 3.3.3 page 63, SO_SNDLOWAT
  int sz = sizeof(val);
  getsockopt(fd, SOL_SOCKET, SO_SNDBUF, &val, &sz);
  val /= 2;  // set send low-water mark at half send buffer size
  setsockopt(fd, SOL_SOCKET, SO_SNDLOWAT, &val, sizeof(val));
#else
  fcntl(fd, F_SETFL, fcntl(fd, F_GETFL, 0) | O_NONBLOCK);  // Non-blocking mode
  fcntl(fd, F_SETFD, FD_CLOEXEC);                          // Set close-on-exec
#endif
}

bool mg_open_listener(struct mg_connection *c, const char *url) {
  MG_SOCKET_TYPE fd = MG_INVALID_SOCKET;
  bool success = false;
  c->loc.port = mg_htons(mg_url_port(url));
  if (!mg_aton(mg_url_host(url), &c->loc)) {
    MG_ERROR(("invalid listening URL: %s", url));
  } else {
    union usa usa;
    socklen_t slen = tousa(&c->loc, &usa);
    int rc, on = 1, af = c->loc.is_ip6 ? AF_INET6 : AF_INET;
    int type = strncmp(url, "udp:", 4) == 0 ? SOCK_DGRAM : SOCK_STREAM;
    int proto = type == SOCK_DGRAM ? IPPROTO_UDP : IPPROTO_TCP;
    (void) on;

    if ((fd = socket(af, type, proto)) == MG_INVALID_SOCKET) {
      MG_ERROR(("socket: %d", MG_SOCK_ERR(-1)));
#if defined(SO_EXCLUSIVEADDRUSE)
    } else if ((rc = setsockopt(fd, SOL_SOCKET, SO_EXCLUSIVEADDRUSE,
                                (char *) &on, sizeof(on))) != 0) {
      // "Using SO_REUSEADDR and SO_EXCLUSIVEADDRUSE"
      MG_ERROR(("setsockopt(SO_EXCLUSIVEADDRUSE): %d %d", on, MG_SOCK_ERR(rc)));
#elif defined(SO_REUSEADDR) && (!defined(LWIP_SOCKET) || SO_REUSE)
    } else if ((rc = setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, (char *) &on,
                                sizeof(on))) != 0) {
      // 1. SO_REUSEADDR semantics on UNIX and Windows is different.  On
      // Windows, SO_REUSEADDR allows to bind a socket to a port without error
      // even if the port is already open by another program. This is not the
      // behavior SO_REUSEADDR was designed for, and leads to hard-to-track
      // failure scenarios.
      //
      // 2. For LWIP, SO_REUSEADDR should be explicitly enabled by defining
      // SO_REUSE = 1 in lwipopts.h, otherwise the code below will compile but
      // won't work! (setsockopt will return EINVAL)
      MG_ERROR(("setsockopt(SO_REUSEADDR): %d", MG_SOCK_ERR(rc)));
#endif
#if MG_IPV6_V6ONLY
      // Bind only to the V6 address, not V4 address on this port
    } else if (c->loc.is_ip6 &&
               (rc = setsockopt(fd, IPPROTO_IPV6, IPV6_V6ONLY, (char *) &on,
                                sizeof(on))) != 0) {
      // See #2089. Allow to bind v4 and v6 sockets on the same port
      MG_ERROR(("setsockopt(IPV6_V6ONLY): %d", MG_SOCK_ERR(rc)));
#endif
    } else if ((rc = bind(fd, &usa.sa, slen)) != 0) {
      MG_ERROR(("bind: %d", MG_SOCK_ERR(rc)));
    } else if ((type == SOCK_STREAM &&
                (rc = listen(fd, MG_SOCK_LISTEN_BACKLOG_SIZE)) != 0)) {
      // NOTE(lsm): FreeRTOS uses backlog value as a connection limit
      // In case port was set to 0, get the real port number
      MG_ERROR(("listen: %d", MG_SOCK_ERR(rc)));
    } else {
      setlocaddr(fd, &c->loc);
      mg_set_non_blocking_mode(fd);
      c->fd = S2PTR(fd);
      MG_EPOLL_ADD(c);
      success = true;
    }
  }
  if (success == false && fd != MG_INVALID_SOCKET) closesocket(fd);
  return success;
}

static long recv_raw(struct mg_connection *c, void *buf, size_t len) {
  long n = 0;
  if (c->is_udp) {
    union usa usa;
    socklen_t slen = tousa(&c->rem, &usa);
    n = recvfrom(FD(c), (char *) buf, len, 0, &usa.sa, &slen);
    if (n > 0) tomgaddr(&usa, &c->rem, slen != sizeof(usa.sin));
  } else {
    n = recv(FD(c), (char *) buf, len, MSG_NONBLOCKING);
  }
  MG_VERBOSE(("%lu %ld %d", c->id, n, MG_SOCK_ERR(n)));
  if (MG_SOCK_PENDING(n)) return MG_IO_WAIT;
  if (MG_SOCK_RESET(n)) return MG_IO_RESET; // MbedTLS, see #1507
  if (n <= 0) return MG_IO_ERR;
  return n;
}

static bool ioalloc(struct mg_connection *c, struct mg_iobuf *io) {
  bool res = false;
  if (io->len >= MG_MAX_RECV_SIZE) {
    mg_error(c, "MG_MAX_RECV_SIZE");
  } else if (io->size <= io->len &&
             !mg_iobuf_resize(io, io->size + MG_IO_SIZE)) {
    mg_error(c, "OOM");
  } else {
    res = true;
  }
  return res;
}

// NOTE(lsm): do only one iteration of reads, cause some systems
// (e.g. FreeRTOS stack) return 0 instead of -1/EWOULDBLOCK when no data
static void read_conn(struct mg_connection *c) {
  if (ioalloc(c, &c->recv)) {
    char *buf = (char *) &c->recv.buf[c->recv.len];
    size_t len = c->recv.size - c->recv.len;
    long n = -1;
    if (c->is_tls) {
      // Do not read to the raw TLS buffer if it already has enough.
      // This is to prevent overflowing c->rtls if our reads are slow
      long m;
      if (c->rtls.len < 16 * 1024 + 40) {  // TLS record, header, MAC, padding
        if (!ioalloc(c, &c->rtls)) return;
        n = recv_raw(c, (char *) &c->rtls.buf[c->rtls.len],
                     c->rtls.size - c->rtls.len);
        if (n > 0) c->rtls.len += (size_t) n;
      }
      // there can still be > 16K from last iteration, always mg_tls_recv()
      m = c->is_tls_hs ? (long) MG_IO_WAIT : mg_tls_recv(c, buf, len);
      if (n == MG_IO_ERR || n == MG_IO_RESET) { // Windows, see #3031
        if (c->rtls.len == 0 || m < 0) {
          // Close only when we have fully drained both rtls and TLS buffers
          c->is_closing = 1;  // or there's nothing we can do about it.
          m = MG_IO_ERR;
        } else { // see #2885
          // TLS buffer is capped to max record size, even though, there can
          // be more than one record, give TLS a chance to process them.
        }
      } else if (c->is_tls_hs) {
        mg_tls_handshake(c);
      }
      n = m;
    } else {
      n = recv_raw(c, buf, len);
    }
    MG_DEBUG(("%lu %ld %lu:%lu:%lu %ld err %d", c->id, c->fd, c->send.len,
              c->recv.len, c->rtls.len, n, MG_SOCK_ERR(n)));
    iolog(c, buf, n, true);
  }
}

static void write_conn(struct mg_connection *c) {
  char *buf = (char *) c->send.buf;
  size_t len = c->send.len;
  long n = c->is_tls ? mg_tls_send(c, buf, len) : mg_io_send(c, buf, len);
  MG_DEBUG(("%lu %ld snd %ld/%ld rcv %ld/%ld n=%ld err=%d", c->id, c->fd,
            (long) c->send.len, (long) c->send.size, (long) c->recv.len,
            (long) c->recv.size, n, MG_SOCK_ERR(n)));
  iolog(c, buf, n, false);
}

static void close_conn(struct mg_connection *c) {
  if (FD(c) != MG_INVALID_SOCKET) {
#if MG_ENABLE_EPOLL
    epoll_ctl(c->mgr->epoll_fd, EPOLL_CTL_DEL, FD(c), NULL);
#endif
    closesocket(FD(c));
#if MG_ENABLE_FREERTOS_TCP
    FreeRTOS_FD_CLR(c->fd, c->mgr->ss, eSELECT_ALL);
#endif
  }
  mg_close_conn(c);
}

static void connect_conn(struct mg_connection *c) {
  union usa usa;
  socklen_t n = sizeof(usa);
  // Use getpeername() to test whether we have connected
  if (getpeername(FD(c), &usa.sa, &n) == 0) {
    c->is_connecting = 0;
    setlocaddr(FD(c), &c->loc);
    mg_call(c, MG_EV_CONNECT, NULL);
    MG_EPOLL_MOD(c, 0);
    if (c->is_tls_hs) mg_tls_handshake(c);
  } else {
    mg_error(c, "socket error");
  }
}

static void setsockopts(struct mg_connection *c) {
#if MG_ENABLE_FREERTOS_TCP || MG_ARCH == MG_ARCH_AZURERTOS || \
    MG_ARCH == MG_ARCH_TIRTOS
  (void) c;
#else
  int on = 1;
#if !defined(SOL_TCP)
#define SOL_TCP IPPROTO_TCP
#endif
  if (setsockopt(FD(c), SOL_TCP, TCP_NODELAY, (char *) &on, sizeof(on)) != 0)
    (void) 0;
  if (setsockopt(FD(c), SOL_SOCKET, SO_KEEPALIVE, (char *) &on, sizeof(on)) !=
      0)
    (void) 0;
#endif
}

void mg_connect_resolved(struct mg_connection *c) {
  int type = c->is_udp ? SOCK_DGRAM : SOCK_STREAM;
  int proto = type == SOCK_DGRAM ? IPPROTO_UDP : IPPROTO_TCP;
  int rc, af = c->rem.is_ip6 ? AF_INET6 : AF_INET;  // c->rem has resolved IP
  c->fd = S2PTR(socket(af, type, proto));           // Create outbound socket
  c->is_resolving = 0;                              // Clear resolving flag
  if (FD(c) == MG_INVALID_SOCKET) {
    mg_error(c, "socket(): %d", MG_SOCK_ERR(-1));
  } else if (c->is_udp) {
    MG_EPOLL_ADD(c);
#if MG_ARCH == MG_ARCH_TIRTOS
    union usa usa;  // TI-RTOS NDK requires binding to receive on UDP sockets
    socklen_t slen = tousa(&c->loc, &usa);
    if ((rc = bind(c->fd, &usa.sa, slen)) != 0)
      MG_ERROR(("bind: %d", MG_SOCK_ERR(rc)));
#endif
    setlocaddr(FD(c), &c->loc);
    mg_call(c, MG_EV_RESOLVE, NULL);
    mg_call(c, MG_EV_CONNECT, NULL);
  } else {
    union usa usa;
    socklen_t slen = tousa(&c->rem, &usa);
    mg_set_non_blocking_mode(FD(c));
    setsockopts(c);
    MG_EPOLL_ADD(c);
    mg_call(c, MG_EV_RESOLVE, NULL);
    rc = connect(FD(c), &usa.sa, slen);  // Attempt to connect
    if (rc == 0) {                       // Success
      setlocaddr(FD(c), &c->loc);
      mg_call(c, MG_EV_CONNECT, NULL);  // Send MG_EV_CONNECT to the user
    } else if (MG_SOCK_PENDING(rc)) {   // Need to wait for TCP handshake
      MG_DEBUG(("%lu %ld -> %M pend", c->id, c->fd, mg_print_ip_port, &c->rem));
      c->is_connecting = 1;
    } else {
      mg_error(c, "connect: %d", MG_SOCK_ERR(rc));
    }
  }
}

static MG_SOCKET_TYPE raccept(MG_SOCKET_TYPE sock, union usa *usa,
                              socklen_t *len) {
  MG_SOCKET_TYPE fd = MG_INVALID_SOCKET;
  do {
    memset(usa, 0, sizeof(*usa));
    fd = accept(sock, &usa->sa, len);
  } while (MG_SOCK_INTR(fd));
  return fd;
}

static void accept_conn(struct mg_mgr *mgr, struct mg_connection *lsn) {
  struct mg_connection *c = NULL;
  union usa usa;
  socklen_t sa_len = sizeof(usa);
  MG_SOCKET_TYPE fd = raccept(FD(lsn), &usa, &sa_len);
  if (fd == MG_INVALID_SOCKET) {
#if MG_ARCH == MG_ARCH_AZURERTOS || defined(__ECOS)
    // AzureRTOS, in non-block socket mode can mark listening socket readable
    // even it is not. See comment for 'select' func implementation in
    // nx_bsd.c That's not an error, just should try later
    if (errno != EAGAIN)
#endif
      MG_ERROR(("%lu accept failed, errno %d", lsn->id, MG_SOCK_ERR(-1)));
#if (MG_ARCH != MG_ARCH_WIN32) && !MG_ENABLE_FREERTOS_TCP && \
    (MG_ARCH != MG_ARCH_TIRTOS) && !MG_ENABLE_POLL && !MG_ENABLE_EPOLL
  } else if ((long) fd >= FD_SETSIZE) {
    MG_ERROR(("%ld > %ld", (long) fd, (long) FD_SETSIZE));
    closesocket(fd);
#endif
  } else if ((c = mg_alloc_conn(mgr)) == NULL) {
    MG_ERROR(("%lu OOM", lsn->id));
    closesocket(fd);
  } else {
    tomgaddr(&usa, &c->rem, sa_len != sizeof(usa.sin));
    LIST_ADD_HEAD(struct mg_connection, &mgr->conns, c);
    c->fd = S2PTR(fd);
    MG_EPOLL_ADD(c);
    mg_set_non_blocking_mode(FD(c));
    setsockopts(c);
    c->is_accepted = 1;
    c->is_hexdumping = lsn->is_hexdumping;
    c->loc = lsn->loc;
    c->pfn = lsn->pfn;
    c->pfn_data = lsn->pfn_data;
    c->fn = lsn->fn;
    c->fn_data = lsn->fn_data;
    MG_DEBUG(("%lu %ld accepted %M -> %M", c->id, c->fd, mg_print_ip_port,
              &c->rem, mg_print_ip_port, &c->loc));
    mg_call(c, MG_EV_OPEN, NULL);
    mg_call(c, MG_EV_ACCEPT, NULL);
  }
}

static bool can_read(const struct mg_connection *c) {
  return c->is_full == false;
}

static bool can_write(const struct mg_connection *c) {
  return c->is_connecting || (c->send.len > 0 && c->is_tls_hs == 0);
}

static bool skip_iotest(const struct mg_connection *c) {
  return (c->is_closing || c->is_resolving || FD(c) == MG_INVALID_SOCKET) ||
         (can_read(c) == false && can_write(c) == false);
}

static void mg_iotest(struct mg_mgr *mgr, int ms) {
#if MG_ENABLE_FREERTOS_TCP
  struct mg_connection *c;
  for (c = mgr->conns; c != NULL; c = c->next) {
    c->is_readable = c->is_writable = 0;
    if (skip_iotest(c)) continue;
    if (can_read(c))
      FreeRTOS_FD_SET(c->fd, mgr->ss, eSELECT_READ | eSELECT_EXCEPT);
    if (can_write(c)) FreeRTOS_FD_SET(c->fd, mgr->ss, eSELECT_WRITE);
    if (c->is_closing) ms = 1;
  }
  FreeRTOS_select(mgr->ss, pdMS_TO_TICKS(ms));
  for (c = mgr->conns; c != NULL; c = c->next) {
    EventBits_t bits = FreeRTOS_FD_ISSET(c->fd, mgr->ss);
    c->is_readable = bits & (eSELECT_READ | eSELECT_EXCEPT) ? 1U : 0;
    c->is_writable = bits & eSELECT_WRITE ? 1U : 0;
    if (c->fd != MG_INVALID_SOCKET)
      FreeRTOS_FD_CLR(c->fd, mgr->ss,
                      eSELECT_READ | eSELECT_EXCEPT | eSELECT_WRITE);
  }
#elif MG_ENABLE_EPOLL
  size_t max = 1;
  for (struct mg_connection *c = mgr->conns; c != NULL; c = c->next) {
    c->is_readable = c->is_writable = 0;
    if (c->rtls.len > 0 || mg_tls_pending(c) > 0) ms = 1, c->is_readable = 1;
    if (can_write(c)) MG_EPOLL_MOD(c, 1);
    if (c->is_closing) ms = 1;
    max++;
  }
  struct epoll_event *evs = (struct epoll_event *) alloca(max * sizeof(evs[0]));
  int n = epoll_wait(mgr->epoll_fd, evs, (int) max, ms);
  for (int i = 0; i < n; i++) {
    struct mg_connection *c = (struct mg_connection *) evs[i].data.ptr;
    if (evs[i].events & EPOLLERR) {
      mg_error(c, "socket error");
    } else if (c->is_readable == 0) {
      bool rd = evs[i].events & (EPOLLIN | EPOLLHUP);
      bool wr = evs[i].events & EPOLLOUT;
      c->is_readable = can_read(c) && rd ? 1U : 0;
      c->is_writable = can_write(c) && wr ? 1U : 0;
      if (c->rtls.len > 0 || mg_tls_pending(c) > 0) c->is_readable = 1;
    }
  }
  (void) skip_iotest;
#elif MG_ENABLE_POLL
  nfds_t n = 0;
  for (struct mg_connection *c = mgr->conns; c != NULL; c = c->next) n++;
  struct pollfd *fds = (struct pollfd *) alloca(n * sizeof(fds[0]));
  memset(fds, 0, n * sizeof(fds[0]));
  n = 0;
  for (struct mg_connection *c = mgr->conns; c != NULL; c = c->next) {
    c->is_readable = c->is_writable = 0;
    if (c->is_closing) ms = 1;
    if (skip_iotest(c)) {
      // Socket not valid, ignore
    } else {
      // Don't wait if TLS is ready
      if (c->rtls.len > 0 || mg_tls_pending(c) > 0) ms = 1;
      fds[n].fd = FD(c);
      if (can_read(c)) fds[n].events |= POLLIN;
      if (can_write(c)) fds[n].events |= POLLOUT;
      n++;
    }
  }

  // MG_INFO(("poll n=%d ms=%d", (int) n, ms));
  if (poll(fds, n, ms) < 0) {
#if MG_ARCH == MG_ARCH_WIN32
    if (n == 0) Sleep(ms);  // On Windows, poll fails if no sockets
#endif
    memset(fds, 0, n * sizeof(fds[0]));
  }
  n = 0;
  for (struct mg_connection *c = mgr->conns; c != NULL; c = c->next) {
    if (skip_iotest(c)) {
      // Socket not valid, ignore
    } else {
      if (fds[n].revents & POLLERR) {
        mg_error(c, "socket error");
      } else {
        c->is_readable =
            (unsigned) (fds[n].revents & (POLLIN | POLLHUP) ? 1 : 0);
        c->is_writable = (unsigned) (fds[n].revents & POLLOUT ? 1 : 0);
        if (c->rtls.len > 0 || mg_tls_pending(c) > 0) c->is_readable = 1;
      }
      n++;
    }
  }
#else
  struct timeval tv = {ms / 1000, (ms % 1000) * 1000}, tv_zero = {0, 0}, *tvp;
  struct mg_connection *c;
  fd_set rset, wset, eset;
  MG_SOCKET_TYPE maxfd = 0;
  int rc;

  FD_ZERO(&rset);
  FD_ZERO(&wset);
  FD_ZERO(&eset);
  tvp = ms < 0 ? NULL : &tv;
  for (c = mgr->conns; c != NULL; c = c->next) {
    c->is_readable = c->is_writable = 0;
    if (skip_iotest(c)) continue;
    FD_SET(FD(c), &eset);
    if (can_read(c)) FD_SET(FD(c), &rset);
    if (can_write(c)) FD_SET(FD(c), &wset);
    if (c->rtls.len > 0 || mg_tls_pending(c) > 0) tvp = &tv_zero;
    if (FD(c) > maxfd) maxfd = FD(c);
    if (c->is_closing) tvp = &tv_zero;
  }

  if ((rc = select((int) maxfd + 1, &rset, &wset, &eset, tvp)) < 0) {
#if MG_ARCH == MG_ARCH_WIN32
    if (maxfd == 0) Sleep(ms);  // On Windows, select fails if no sockets
#else
    MG_ERROR(("select: %d %d", rc, MG_SOCK_ERR(rc)));
#endif
    FD_ZERO(&rset);
    FD_ZERO(&wset);
    FD_ZERO(&eset);
  }

  for (c = mgr->conns; c != NULL; c = c->next) {
    if (FD(c) != MG_INVALID_SOCKET && FD_ISSET(FD(c), &eset)) {
      mg_error(c, "socket error");
    } else {
      c->is_readable = FD(c) != MG_INVALID_SOCKET && FD_ISSET(FD(c), &rset);
      c->is_writable = FD(c) != MG_INVALID_SOCKET && FD_ISSET(FD(c), &wset);
      if (c->rtls.len > 0 || mg_tls_pending(c) > 0) c->is_readable = 1;
    }
  }
#endif
}

static bool mg_socketpair(MG_SOCKET_TYPE sp[2], union usa usa[2]) {
  socklen_t n = sizeof(usa[0].sin);
  bool success = false;

  sp[0] = sp[1] = MG_INVALID_SOCKET;
  (void) memset(&usa[0], 0, sizeof(usa[0]));
  usa[0].sin.sin_family = AF_INET;
  *(uint32_t *) &usa->sin.sin_addr = mg_htonl(0x7f000001U);  // 127.0.0.1
  usa[1] = usa[0];

  if ((sp[0] = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)) != MG_INVALID_SOCKET &&
      (sp[1] = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)) != MG_INVALID_SOCKET &&
      bind(sp[0], &usa[0].sa, n) == 0 &&          //
      bind(sp[1], &usa[1].sa, n) == 0 &&          //
      getsockname(sp[0], &usa[0].sa, &n) == 0 &&  //
      getsockname(sp[1], &usa[1].sa, &n) == 0 &&  //
      connect(sp[0], &usa[1].sa, n) == 0 &&       //
      connect(sp[1], &usa[0].sa, n) == 0) {       //
    success = true;
  }
  if (!success) {
    if (sp[0] != MG_INVALID_SOCKET) closesocket(sp[0]);
    if (sp[1] != MG_INVALID_SOCKET) closesocket(sp[1]);
    sp[0] = sp[1] = MG_INVALID_SOCKET;
  }
  return success;
}

// mg_wakeup() event handler
static void wufn(struct mg_connection *c, int ev, void *ev_data) {
  if (ev == MG_EV_READ) {
    unsigned long *id = (unsigned long *) c->recv.buf;
    // MG_INFO(("Got data"));
    // mg_hexdump(c->recv.buf, c->recv.len);
    if (c->recv.len >= sizeof(*id)) {
      struct mg_connection *t;
      for (t = c->mgr->conns; t != NULL; t = t->next) {
        if (t->id == *id) {
          struct mg_str data = mg_str_n((char *) c->recv.buf + sizeof(*id),
                                        c->recv.len - sizeof(*id));
          mg_call(t, MG_EV_WAKEUP, &data);
        }
      }
    }
    c->recv.len = 0;  // Consume received data
  } else if (ev == MG_EV_CLOSE) {
    closesocket(c->mgr->pipe);         // When we're closing, close the other
    c->mgr->pipe = MG_INVALID_SOCKET;  // side of the socketpair, too
  }
  (void) ev_data;
}

bool mg_wakeup_init(struct mg_mgr *mgr) {
  bool ok = false;
  if (mgr->pipe == MG_INVALID_SOCKET) {
    union usa usa[2];
    MG_SOCKET_TYPE sp[2] = {MG_INVALID_SOCKET, MG_INVALID_SOCKET};
    struct mg_connection *c = NULL;
    if (!mg_socketpair(sp, usa)) {
      MG_ERROR(("Cannot create socket pair"));
    } else if ((c = mg_wrapfd(mgr, (int) sp[1], wufn, NULL)) == NULL) {
      closesocket(sp[0]);
      closesocket(sp[1]);
      sp[0] = sp[1] = MG_INVALID_SOCKET;
    } else {
      tomgaddr(&usa[0], &c->rem, false);
      MG_DEBUG(("%lu %p pipe %lu", c->id, c->fd, (unsigned long) sp[0]));
      mgr->pipe = sp[0];
      ok = true;
    }
  }
  return ok;
}

bool mg_wakeup(struct mg_mgr *mgr, unsigned long conn_id, const void *buf,
               size_t len) {
  if (mgr->pipe != MG_INVALID_SOCKET && conn_id > 0) {
    char *extended_buf = (char *) alloca(len + sizeof(conn_id));
    memcpy(extended_buf, &conn_id, sizeof(conn_id));
    memcpy(extended_buf + sizeof(conn_id), buf, len);
    send(mgr->pipe, extended_buf, len + sizeof(conn_id), MSG_NONBLOCKING);
    return true;
  }
  return false;
}

void mg_mgr_poll(struct mg_mgr *mgr, int ms) {
  struct mg_connection *c, *tmp;
  uint64_t now;

  mg_iotest(mgr, ms);
  now = mg_millis();
  mg_timer_poll(&mgr->timers, now);

  for (c = mgr->conns; c != NULL; c = tmp) {
    bool is_resp = c->is_resp;
    tmp = c->next;
    mg_call(c, MG_EV_POLL, &now);
    if (is_resp && !c->is_resp) {
      long n = 0;
      mg_call(c, MG_EV_READ, &n);
    }
    MG_VERBOSE(("%lu %c%c %c%c%c%c%c %lu %lu", c->id,
                c->is_readable ? 'r' : '-', c->is_writable ? 'w' : '-',
                c->is_tls ? 'T' : 't', c->is_connecting ? 'C' : 'c',
                c->is_tls_hs ? 'H' : 'h', c->is_resolving ? 'R' : 'r',
                c->is_closing ? 'C' : 'c', mg_tls_pending(c), c->rtls.len));
    if (c->is_resolving || c->is_closing) {
      // Do nothing
    } else if (c->is_listening && c->is_udp == 0) {
      if (c->is_readable) accept_conn(mgr, c);
    } else if (c->is_connecting) {
      if (c->is_readable || c->is_writable) connect_conn(c);
      //} else if (c->is_tls_hs) {
      //  if ((c->is_readable || c->is_writable)) mg_tls_handshake(c);
    } else {
      if (c->is_readable) read_conn(c);
      if (c->is_writable) write_conn(c);
    }

    if (c->is_draining && c->send.len == 0) c->is_closing = 1;
    if (c->is_closing) close_conn(c);
  }
}
#endif

#ifdef MG_ENABLE_LINES
#line 1 "src/ssi.c"
#endif




#ifndef MG_MAX_SSI_DEPTH
#define MG_MAX_SSI_DEPTH 5
#endif

#ifndef MG_SSI_BUFSIZ
#define MG_SSI_BUFSIZ 1024
#endif

#if MG_ENABLE_SSI
static char *mg_ssi(const char *path, const char *root, int depth) {
  struct mg_iobuf b = {NULL, 0, 0, MG_IO_SIZE};
  FILE *fp = fopen(path, "rb");
  if (fp != NULL) {
    char buf[MG_SSI_BUFSIZ], arg[sizeof(buf)];
    int ch, intag = 0;
    size_t len = 0;
    buf[0] = arg[0] = '\0';
    while ((ch = fgetc(fp)) != EOF) {
      if (intag && ch == '>' && buf[len - 1] == '-' && buf[len - 2] == '-') {
        buf[len++] = (char) (ch & 0xff);
        buf[len] = '\0';
        if (sscanf(buf, "<!--#include file=\"%[^\"]", arg) > 0) {
          char tmp[MG_PATH_MAX + MG_SSI_BUFSIZ + 10],
              *p = (char *) path + strlen(path), *data;
          while (p > path && p[-1] != MG_DIRSEP && p[-1] != '/') p--;
          mg_snprintf(tmp, sizeof(tmp), "%.*s%s", (int) (p - path), path, arg);
          if (depth < MG_MAX_SSI_DEPTH &&
              (data = mg_ssi(tmp, root, depth + 1)) != NULL) {
            mg_iobuf_add(&b, b.len, data, strlen(data));
            free(data);
          } else {
            MG_ERROR(("%s: file=%s error or too deep", path, arg));
          }
        } else if (sscanf(buf, "<!--#include virtual=\"%[^\"]", arg) > 0) {
          char tmp[MG_PATH_MAX + MG_SSI_BUFSIZ + 10], *data;
          mg_snprintf(tmp, sizeof(tmp), "%s%s", root, arg);
          if (depth < MG_MAX_SSI_DEPTH &&
              (data = mg_ssi(tmp, root, depth + 1)) != NULL) {
            mg_iobuf_add(&b, b.len, data, strlen(data));
            free(data);
          } else {
            MG_ERROR(("%s: virtual=%s error or too deep", path, arg));
          }
        } else {
          // Unknown SSI tag
          MG_ERROR(("Unknown SSI tag: %.*s", (int) len, buf));
          mg_iobuf_add(&b, b.len, buf, len);
        }
        intag = 0;
        len = 0;
      } else if (ch == '<') {
        intag = 1;
        if (len > 0) mg_iobuf_add(&b, b.len, buf, len);
        len = 0;
        buf[len++] = (char) (ch & 0xff);
      } else if (intag) {
        if (len == 5 && strncmp(buf, "<!--#", 5) != 0) {
          intag = 0;
        } else if (len >= sizeof(buf) - 2) {
          MG_ERROR(("%s: SSI tag is too large", path));
          len = 0;
        }
        buf[len++] = (char) (ch & 0xff);
      } else {
        buf[len++] = (char) (ch & 0xff);
        if (len >= sizeof(buf)) {
          mg_iobuf_add(&b, b.len, buf, len);
          len = 0;
        }
      }
    }
    if (len > 0) mg_iobuf_add(&b, b.len, buf, len);
    if (b.len > 0) mg_iobuf_add(&b, b.len, "", 1);  // nul-terminate
    fclose(fp);
  }
  (void) depth;
  (void) root;
  return (char *) b.buf;
}

void mg_http_serve_ssi(struct mg_connection *c, const char *root,
                       const char *fullpath) {
  const char *headers = "Content-Type: text/html; charset=utf-8\r\n";
  char *data = mg_ssi(fullpath, root, 0);
  mg_http_reply(c, 200, headers, "%s", data == NULL ? "" : data);
  free(data);
}
#else
void mg_http_serve_ssi(struct mg_connection *c, const char *root,
                       const char *fullpath) {
  mg_http_reply(c, 501, NULL, "SSI not enabled");
  (void) root, (void) fullpath;
}
#endif

#ifdef MG_ENABLE_LINES
#line 1 "src/str.c"
#endif


struct mg_str mg_str_s(const char *s) {
  struct mg_str str = {(char *) s, s == NULL ? 0 : strlen(s)};
  return str;
}

struct mg_str mg_str_n(const char *s, size_t n) {
  struct mg_str str = {(char *) s, n};
  return str;
}

static int mg_tolc(char c) {
  return (c >= 'A' && c <= 'Z') ? c + 'a' - 'A' : c;
}

int mg_casecmp(const char *s1, const char *s2) {
  int diff = 0;
  do {
    int c = mg_tolc(*s1++), d = mg_tolc(*s2++);
    diff = c - d;
  } while (diff == 0 && s1[-1] != '\0');
  return diff;
}

struct mg_str mg_strdup(const struct mg_str s) {
  struct mg_str r = {NULL, 0};
  if (s.len > 0 && s.buf != NULL) {
    char *sc = (char *) calloc(1, s.len + 1);
    if (sc != NULL) {
      memcpy(sc, s.buf, s.len);
      sc[s.len] = '\0';
      r.buf = sc;
      r.len = s.len;
    }
  }
  return r;
}

int mg_strcmp(const struct mg_str str1, const struct mg_str str2) {
  size_t i = 0;
  while (i < str1.len && i < str2.len) {
    int c1 = str1.buf[i];
    int c2 = str2.buf[i];
    if (c1 < c2) return -1;
    if (c1 > c2) return 1;
    i++;
  }
  if (i < str1.len) return 1;
  if (i < str2.len) return -1;
  return 0;
}

int mg_strcasecmp(const struct mg_str str1, const struct mg_str str2) {
  size_t i = 0;
  while (i < str1.len && i < str2.len) {
    int c1 = mg_tolc(str1.buf[i]);
    int c2 = mg_tolc(str2.buf[i]);
    if (c1 < c2) return -1;
    if (c1 > c2) return 1;
    i++;
  }
  if (i < str1.len) return 1;
  if (i < str2.len) return -1;
  return 0;
}

bool mg_match(struct mg_str s, struct mg_str p, struct mg_str *caps) {
  size_t i = 0, j = 0, ni = 0, nj = 0;
  if (caps) caps->buf = NULL, caps->len = 0;
  while (i < p.len || j < s.len) {
    if (i < p.len && j < s.len &&
        (p.buf[i] == '?' ||
         (p.buf[i] != '*' && p.buf[i] != '#' && s.buf[j] == p.buf[i]))) {
      if (caps == NULL) {
      } else if (p.buf[i] == '?') {
        caps->buf = &s.buf[j], caps->len = 1;     // Finalize `?` cap
        caps++, caps->buf = NULL, caps->len = 0;  // Init next cap
      } else if (caps->buf != NULL && caps->len == 0) {
        caps->len = (size_t) (&s.buf[j] - caps->buf);  // Finalize current cap
        caps++, caps->len = 0, caps->buf = NULL;       // Init next cap
      }
      i++, j++;
    } else if (i < p.len && (p.buf[i] == '*' || p.buf[i] == '#')) {
      if (caps && !caps->buf) caps->len = 0, caps->buf = &s.buf[j];  // Init cap
      ni = i++, nj = j + 1;
    } else if (nj > 0 && nj <= s.len && (p.buf[ni] == '#' || s.buf[j] != '/')) {
      i = ni, j = nj;
      if (caps && caps->buf == NULL && caps->len == 0) {
        caps--, caps->len = 0;  // Restart previous cap
      }
    } else {
      return false;
    }
  }
  if (caps && caps->buf && caps->len == 0) {
    caps->len = (size_t) (&s.buf[j] - caps->buf);
  }
  return true;
}

bool mg_span(struct mg_str s, struct mg_str *a, struct mg_str *b, char sep) {
  if (s.len == 0 || s.buf == NULL) {
    return false;  // Empty string, nothing to span - fail
  } else {
    size_t len = 0;
    while (len < s.len && s.buf[len] != sep) len++;  // Find separator
    if (a) *a = mg_str_n(s.buf, len);                // Init a
    if (b) *b = mg_str_n(s.buf + len, s.len - len);  // Init b
    if (b && len < s.len) b->buf++, b->len--;        // Skip separator
    return true;
  }
}

bool mg_str_to_num(struct mg_str str, int base, void *val, size_t val_len) {
  size_t i = 0, ndigits = 0;
  uint64_t max = val_len == sizeof(uint8_t)    ? 0xFF
                 : val_len == sizeof(uint16_t) ? 0xFFFF
                 : val_len == sizeof(uint32_t) ? 0xFFFFFFFF
                                               : (uint64_t) ~0;
  uint64_t result = 0;
  if (max == (uint64_t) ~0 && val_len != sizeof(uint64_t)) return false;
  if (base == 0 && str.len >= 2) {
    if (str.buf[i] == '0') {
      i++;
      base = str.buf[i] == 'b' ? 2 : str.buf[i] == 'x' ? 16 : 10;
      if (base != 10) ++i;
    } else {
      base = 10;
    }
  }
  switch (base) {
    case 2:
      while (i < str.len && (str.buf[i] == '0' || str.buf[i] == '1')) {
        uint64_t digit = (uint64_t) (str.buf[i] - '0');
        if (result > max / 2) return false;  // Overflow
        result *= 2;
        if (result > max - digit) return false;  // Overflow
        result += digit;
        i++, ndigits++;
      }
      break;
    case 10:
      while (i < str.len && str.buf[i] >= '0' && str.buf[i] <= '9') {
        uint64_t digit = (uint64_t) (str.buf[i] - '0');
        if (result > max / 10) return false;  // Overflow
        result *= 10;
        if (result > max - digit) return false;  // Overflow
        result += digit;
        i++, ndigits++;
      }
      break;
    case 16:
      while (i < str.len) {
        char c = str.buf[i];
        uint64_t digit = (c >= '0' && c <= '9')   ? (uint64_t) (c - '0')
                         : (c >= 'A' && c <= 'F') ? (uint64_t) (c - '7')
                         : (c >= 'a' && c <= 'f') ? (uint64_t) (c - 'W')
                                                  : (uint64_t) ~0;
        if (digit == (uint64_t) ~0) break;
        if (result > max / 16) return false;  // Overflow
        result *= 16;
        if (result > max - digit) return false;  // Overflow
        result += digit;
        i++, ndigits++;
      }
      break;
    default:
      return false;
  }
  if (ndigits == 0) return false;
  if (i != str.len) return false;
  if (val_len == 1) {
    *((uint8_t *) val) = (uint8_t) result;
  } else if (val_len == 2) {
    *((uint16_t *) val) = (uint16_t) result;
  } else if (val_len == 4) {
    *((uint32_t *) val) = (uint32_t) result;
  } else {
    *((uint64_t *) val) = (uint64_t) result;
  }
  return true;
}

#ifdef MG_ENABLE_LINES
#line 1 "src/timer.c"
#endif



#define MG_TIMER_CALLED 4

void mg_timer_init(struct mg_timer **head, struct mg_timer *t, uint64_t ms,
                   unsigned flags, void (*fn)(void *), void *arg) {
  t->id = 0, t->period_ms = ms, t->expire = 0;
  t->flags = flags, t->fn = fn, t->arg = arg, t->next = *head;
  *head = t;
}

void mg_timer_free(struct mg_timer **head, struct mg_timer *t) {
  while (*head && *head != t) head = &(*head)->next;
  if (*head) *head = t->next;
}

// t: expiration time, prd: period, now: current time. Return true if expired
bool mg_timer_expired(uint64_t *t, uint64_t prd, uint64_t now) {
  if (now + prd < *t) *t = 0;                    // Time wrapped? Reset timer
  if (*t == 0) *t = now + prd;                   // Firt poll? Set expiration
  if (*t > now) return false;                    // Not expired yet, return
  *t = (now - *t) > prd ? now + prd : *t + prd;  // Next expiration time
  return true;                                   // Expired, return true
}

void mg_timer_poll(struct mg_timer **head, uint64_t now_ms) {
  struct mg_timer *t, *tmp;
  for (t = *head; t != NULL; t = tmp) {
    bool once = t->expire == 0 && (t->flags & MG_TIMER_RUN_NOW) &&
                !(t->flags & MG_TIMER_CALLED);  // Handle MG_TIMER_NOW only once
    bool expired = mg_timer_expired(&t->expire, t->period_ms, now_ms);
    tmp = t->next;
    if (!once && !expired) continue;
    if ((t->flags & MG_TIMER_REPEAT) || !(t->flags & MG_TIMER_CALLED)) {
      t->fn(t->arg);
    }
    t->flags |= MG_TIMER_CALLED;
  }
}

#ifdef MG_ENABLE_LINES
#line 1 "src/tls_aes128.c"
#endif
/******************************************************************************
 *
 * THIS SOURCE CODE IS HEREBY PLACED INTO THE PUBLIC DOMAIN FOR THE GOOD OF ALL
 *
 * This is a simple and straightforward implementation of the AES Rijndael
 * 128-bit block cipher designed by Vincent Rijmen and Joan Daemen. The focus
 * of this work was correctness & accuracy.  It is written in 'C' without any
 * particular focus upon optimization or speed. It should be endian (memory
 * byte order) neutral since the few places that care are handled explicitly.
 *
 * This implementation of Rijndael was created by Steven M. Gibson of GRC.com.
 *
 * It is intended for general purpose use, but was written in support of GRC's
 * reference implementation of the SQRL (Secure Quick Reliable Login) client.
 *
 * See:    http://csrc.nist.gov/archive/aes/rijndael/wsdindex.html
 *
 * NO COPYRIGHT IS CLAIMED IN THIS WORK, HOWEVER, NEITHER IS ANY WARRANTY MADE
 * REGARDING ITS FITNESS FOR ANY PARTICULAR PURPOSE. USE IT AT YOUR OWN RISK.
 *
 *******************************************************************************/

/******************************************************************************/
#define AES_DECRYPTION 1  // whether AES decryption is supported
/******************************************************************************/

#define MG_ENCRYPT 1  // specify whether we're encrypting
#define MG_DECRYPT 0  // or decrypting





#if MG_TLS == MG_TLS_BUILTIN
/******************************************************************************
 *  AES_INIT_KEYGEN_TABLES : MUST be called once before any AES use
 ******************************************************************************/
static void aes_init_keygen_tables(void);

/******************************************************************************
 *  AES_SETKEY : called to expand the key for encryption or decryption
 ******************************************************************************/
static int aes_setkey(aes_context *ctx,  // pointer to context
                      int mode,          // 1 or 0 for Encrypt/Decrypt
                      const unsigned char *key,  // AES input key
                      unsigned int keysize);  // size in bytes (must be 16, 24, 32 for
                                      // 128, 192 or 256-bit keys respectively)
                                      // returns 0 for success

/******************************************************************************
 *  AES_CIPHER : called to encrypt or decrypt ONE 128-bit block of data
 ******************************************************************************/
static int aes_cipher(aes_context *ctx,       // pointer to context
                      const unsigned char input[16],  // 128-bit block to en/decipher
                      unsigned char output[16]);      // 128-bit output result block
                                              // returns 0 for success

/******************************************************************************
 *  GCM_CONTEXT : GCM context / holds keytables, instance data, and AES ctx
 ******************************************************************************/
typedef struct {
  int mode;             // cipher direction: encrypt/decrypt
  uint64_t len;         // cipher data length processed so far
  uint64_t add_len;     // total add data length
  uint64_t HL[16];      // precalculated lo-half HTable
  uint64_t HH[16];      // precalculated hi-half HTable
  unsigned char base_ectr[16];  // first counter-mode cipher output for tag
  unsigned char y[16];          // the current cipher-input IV|Counter value
  unsigned char buf[16];        // buf working value
  aes_context aes_ctx;  // cipher context used
} gcm_context;

/******************************************************************************
 *  GCM_SETKEY : sets the GCM (and AES) keying material for use
 ******************************************************************************/
static int gcm_setkey(
    gcm_context *ctx,   // caller-provided context ptr
    const unsigned char *key,   // pointer to cipher key
    const unsigned int keysize  // size in bytes (must be 16, 24, 32 for
                        // 128, 192 or 256-bit keys respectively)
);                      // returns 0 for success

/******************************************************************************
 *
 *  GCM_CRYPT_AND_TAG
 *
 *  This either encrypts or decrypts the user-provided data and, either
 *  way, generates an authentication tag of the requested length. It must be
 *  called with a GCM context whose key has already been set with GCM_SETKEY.
 *
 *  The user would typically call this explicitly to ENCRYPT a buffer of data
 *  and optional associated data, and produce its an authentication tag.
 *
 *  To reverse the process the user would typically call the companion
 *  GCM_AUTH_DECRYPT function to decrypt data and verify a user-provided
 *  authentication tag.  The GCM_AUTH_DECRYPT function calls this function
 *  to perform its decryption and tag generation, which it then compares.
 *
 ******************************************************************************/
static int gcm_crypt_and_tag(
    gcm_context *ctx,    // gcm context with key already setup
    int mode,            // cipher direction: MG_ENCRYPT (1) or MG_DECRYPT (0)
    const unsigned char *iv,     // pointer to the 12-byte initialization vector
    size_t iv_len,       // byte length if the IV. should always be 12
    const unsigned char *add,    // pointer to the non-ciphered additional data
    size_t add_len,      // byte length of the additional AEAD data
    const unsigned char *input,  // pointer to the cipher data source
    unsigned char *output,       // pointer to the cipher data destination
    size_t length,       // byte length of the cipher data
    unsigned char *tag,          // pointer to the tag to be generated
    size_t tag_len);     // byte length of the tag to be generated

/******************************************************************************
 *
 *  GCM_START
 *
 *  Given a user-provided GCM context, this initializes it, sets the encryption
 *  mode, and preprocesses the initialization vector and additional AEAD data.
 *
 ******************************************************************************/
static int gcm_start(
    gcm_context *ctx,  // pointer to user-provided GCM context
    int mode,          // MG_ENCRYPT (1) or MG_DECRYPT (0)
    const unsigned char *iv,   // pointer to initialization vector
    size_t iv_len,     // IV length in bytes (should == 12)
    const unsigned char *add,  // pointer to additional AEAD data (NULL if none)
    size_t add_len);   // length of additional AEAD data (bytes)

/******************************************************************************
 *
 *  GCM_UPDATE
 *
 *  This is called once or more to process bulk plaintext or ciphertext data.
 *  We give this some number of bytes of input and it returns the same number
 *  of output bytes. If called multiple times (which is fine) all but the final
 *  invocation MUST be called with length mod 16 == 0. (Only the final call can
 *  have a partial block length of < 128 bits.)
 *
 ******************************************************************************/
static int gcm_update(gcm_context *ctx,  // pointer to user-provided GCM context
                      size_t length,     // length, in bytes, of data to process
                      const unsigned char *input,  // pointer to source data
                      unsigned char *output);      // pointer to destination data

/******************************************************************************
 *
 *  GCM_FINISH
 *
 *  This is called once after all calls to GCM_UPDATE to finalize the GCM.
 *  It performs the final GHASH to produce the resulting authentication TAG.
 *
 ******************************************************************************/
static int gcm_finish(
    gcm_context *ctx,  // pointer to user-provided GCM context
    unsigned char *tag,        // ptr to tag buffer - NULL if tag_len = 0
    size_t tag_len);   // length, in bytes, of the tag-receiving buf

/******************************************************************************
 *
 *  GCM_ZERO_CTX
 *
 *  The GCM context contains both the GCM context and the AES context.
 *  This includes keying and key-related material which is security-
 *  sensitive, so it MUST be zeroed after use. This function does that.
 *
 ******************************************************************************/
static void gcm_zero_ctx(gcm_context *ctx);

/******************************************************************************
 *
 * THIS SOURCE CODE IS HEREBY PLACED INTO THE PUBLIC DOMAIN FOR THE GOOD OF ALL
 *
 * This is a simple and straightforward implementation of the AES Rijndael
 * 128-bit block cipher designed by Vincent Rijmen and Joan Daemen. The focus
 * of this work was correctness & accuracy.  It is written in 'C' without any
 * particular focus upon optimization or speed. It should be endian (memory
 * byte order) neutral since the few places that care are handled explicitly.
 *
 * This implementation of Rijndael was created by Steven M. Gibson of GRC.com.
 *
 * It is intended for general purpose use, but was written in support of GRC's
 * reference implementation of the SQRL (Secure Quick Reliable Login) client.
 *
 * See:    http://csrc.nist.gov/archive/aes/rijndael/wsdindex.html
 *
 * NO COPYRIGHT IS CLAIMED IN THIS WORK, HOWEVER, NEITHER IS ANY WARRANTY MADE
 * REGARDING ITS FITNESS FOR ANY PARTICULAR PURPOSE. USE IT AT YOUR OWN RISK.
 *
 *******************************************************************************/

static int aes_tables_inited = 0;  // run-once flag for performing key
                                   // expasion table generation (see below)
/*
 *  The following static local tables must be filled-in before the first use of
 *  the GCM or AES ciphers. They are used for the AES key expansion/scheduling
 *  and once built are read-only and thread safe. The "gcm_initialize" function
 *  must be called once during system initialization to populate these arrays
 *  for subsequent use by the AES key scheduler. If they have not been built
 *  before attempted use, an error will be returned to the caller.
 *
 *  NOTE: GCM Encryption/Decryption does NOT REQUIRE AES decryption. Since
 *  GCM uses AES in counter-mode, where the AES cipher output is XORed with
 *  the GCM input, we ONLY NEED AES encryption.  Thus, to save space AES
 *  decryption is typically disabled by setting AES_DECRYPTION to 0 in aes.h.
 */
// We always need our forward tables
static unsigned char FSb[256];     // Forward substitution box (FSb)
static uint32_t FT0[256];  // Forward key schedule assembly tables
static uint32_t FT1[256];
static uint32_t FT2[256];
static uint32_t FT3[256];

#if AES_DECRYPTION         // We ONLY need reverse for decryption
static unsigned char RSb[256];     // Reverse substitution box (RSb)
static uint32_t RT0[256];  // Reverse key schedule assembly tables
static uint32_t RT1[256];
static uint32_t RT2[256];
static uint32_t RT3[256];
#endif /* AES_DECRYPTION */

static uint32_t RCON[10];  // AES round constants

/*
 * Platform Endianness Neutralizing Load and Store Macro definitions
 * AES wants platform-neutral Little Endian (LE) byte ordering
 */
#define GET_UINT32_LE(n, b, i)                                               \
  {                                                                          \
    (n) = ((uint32_t) (b)[(i)]) | ((uint32_t) (b)[(i) + 1] << 8) |           \
          ((uint32_t) (b)[(i) + 2] << 16) | ((uint32_t) (b)[(i) + 3] << 24); \
  }

#define PUT_UINT32_LE(n, b, i)          \
  {                                     \
    (b)[(i)] = (unsigned char) ((n));           \
    (b)[(i) + 1] = (unsigned char) ((n) >> 8);  \
    (b)[(i) + 2] = (unsigned char) ((n) >> 16); \
    (b)[(i) + 3] = (unsigned char) ((n) >> 24); \
  }

/*
 *  AES forward and reverse encryption round processing macros
 */
#define AES_FROUND(X0, X1, X2, X3, Y0, Y1, Y2, Y3)          \
  {                                                         \
    X0 = *RK++ ^ FT0[(Y0) & 0xFF] ^ FT1[(Y1 >> 8) & 0xFF] ^ \
         FT2[(Y2 >> 16) & 0xFF] ^ FT3[(Y3 >> 24) & 0xFF];   \
                                                            \
    X1 = *RK++ ^ FT0[(Y1) & 0xFF] ^ FT1[(Y2 >> 8) & 0xFF] ^ \
         FT2[(Y3 >> 16) & 0xFF] ^ FT3[(Y0 >> 24) & 0xFF];   \
                                                            \
    X2 = *RK++ ^ FT0[(Y2) & 0xFF] ^ FT1[(Y3 >> 8) & 0xFF] ^ \
         FT2[(Y0 >> 16) & 0xFF] ^ FT3[(Y1 >> 24) & 0xFF];   \
                                                            \
    X3 = *RK++ ^ FT0[(Y3) & 0xFF] ^ FT1[(Y0 >> 8) & 0xFF] ^ \
         FT2[(Y1 >> 16) & 0xFF] ^ FT3[(Y2 >> 24) & 0xFF];   \
  }

#define AES_RROUND(X0, X1, X2, X3, Y0, Y1, Y2, Y3)          \
  {                                                         \
    X0 = *RK++ ^ RT0[(Y0) & 0xFF] ^ RT1[(Y3 >> 8) & 0xFF] ^ \
         RT2[(Y2 >> 16) & 0xFF] ^ RT3[(Y1 >> 24) & 0xFF];   \
                                                            \
    X1 = *RK++ ^ RT0[(Y1) & 0xFF] ^ RT1[(Y0 >> 8) & 0xFF] ^ \
         RT2[(Y3 >> 16) & 0xFF] ^ RT3[(Y2 >> 24) & 0xFF];   \
                                                            \
    X2 = *RK++ ^ RT0[(Y2) & 0xFF] ^ RT1[(Y1 >> 8) & 0xFF] ^ \
         RT2[(Y0 >> 16) & 0xFF] ^ RT3[(Y3 >> 24) & 0xFF];   \
                                                            \
    X3 = *RK++ ^ RT0[(Y3) & 0xFF] ^ RT1[(Y2 >> 8) & 0xFF] ^ \
         RT2[(Y1 >> 16) & 0xFF] ^ RT3[(Y0 >> 24) & 0xFF];   \
  }

/*
 *  These macros improve the readability of the key
 *  generation initialization code by collapsing
 *  repetitive common operations into logical pieces.
 */
#define ROTL8(x) ((x << 8) & 0xFFFFFFFF) | (x >> 24)
#define XTIME(x) ((x << 1) ^ ((x & 0x80) ? 0x1B : 0x00))
#define MUL(x, y) ((x && y) ? pow[(log[x] + log[y]) % 255] : 0)
#define MIX(x, y)                     \
  {                                   \
    y = ((y << 1) | (y >> 7)) & 0xFF; \
    x ^= y;                           \
  }
#define CPY128     \
  {                \
    *RK++ = *SK++; \
    *RK++ = *SK++; \
    *RK++ = *SK++; \
    *RK++ = *SK++; \
  }

/******************************************************************************
 *
 *  AES_INIT_KEYGEN_TABLES
 *
 *  Fills the AES key expansion tables allocated above with their static
 *  data. This is not "per key" data, but static system-wide read-only
 *  table data. THIS FUNCTION IS NOT THREAD SAFE. It must be called once
 *  at system initialization to setup the tables for all subsequent use.
 *
 ******************************************************************************/
void aes_init_keygen_tables(void) {
  int i, x, y, z;  // general purpose iteration and computation locals
  int pow[256];
  int log[256];

  if (aes_tables_inited) return;

  // fill the 'pow' and 'log' tables over GF(2^8)
  for (i = 0, x = 1; i < 256; i++) {
    pow[i] = x;
    log[x] = i;
    x = (x ^ XTIME(x)) & 0xFF;
  }
  // compute the round constants
  for (i = 0, x = 1; i < 10; i++) {
    RCON[i] = (uint32_t) x;
    x = XTIME(x) & 0xFF;
  }
  // fill the forward and reverse substitution boxes
  FSb[0x00] = 0x63;
#if AES_DECRYPTION  // whether AES decryption is supported
  RSb[0x63] = 0x00;
#endif /* AES_DECRYPTION */

  for (i = 1; i < 256; i++) {
    x = y = pow[255 - log[i]];
    MIX(x, y);
    MIX(x, y);
    MIX(x, y);
    MIX(x, y);
    FSb[i] = (unsigned char) (x ^= 0x63);
#if AES_DECRYPTION  // whether AES decryption is supported
    RSb[x] = (unsigned char) i;
#endif /* AES_DECRYPTION */
  }
  // generate the forward and reverse key expansion tables
  for (i = 0; i < 256; i++) {
    x = FSb[i];
    y = XTIME(x) & 0xFF;
    z = (y ^ x) & 0xFF;

    FT0[i] = ((uint32_t) y) ^ ((uint32_t) x << 8) ^ ((uint32_t) x << 16) ^
             ((uint32_t) z << 24);

    FT1[i] = ROTL8(FT0[i]);
    FT2[i] = ROTL8(FT1[i]);
    FT3[i] = ROTL8(FT2[i]);

#if AES_DECRYPTION  // whether AES decryption is supported
    x = RSb[i];

    RT0[i] = ((uint32_t) MUL(0x0E, x)) ^ ((uint32_t) MUL(0x09, x) << 8) ^
             ((uint32_t) MUL(0x0D, x) << 16) ^ ((uint32_t) MUL(0x0B, x) << 24);

    RT1[i] = ROTL8(RT0[i]);
    RT2[i] = ROTL8(RT1[i]);
    RT3[i] = ROTL8(RT2[i]);
#endif /* AES_DECRYPTION */
  }
  aes_tables_inited = 1;  // flag that the tables have been generated
}  // to permit subsequent use of the AES cipher

/******************************************************************************
 *
 *  AES_SET_ENCRYPTION_KEY
 *
 *  This is called by 'aes_setkey' when we're establishing a key for
 *  subsequent encryption.  We give it a pointer to the encryption
 *  context, a pointer to the key, and the key's length in bytes.
 *  Valid lengths are: 16, 24 or 32 bytes (128, 192, 256 bits).
 *
 ******************************************************************************/
static int aes_set_encryption_key(aes_context *ctx, const unsigned char *key,
                                  unsigned int keysize) {
  unsigned int i;                  // general purpose iteration local
  uint32_t *RK = ctx->rk;  // initialize our RoundKey buffer pointer

  for (i = 0; i < (keysize >> 2); i++) {
    GET_UINT32_LE(RK[i], key, i << 2);
  }

  switch (ctx->rounds) {
    case 10:
      for (i = 0; i < 10; i++, RK += 4) {
        RK[4] = RK[0] ^ RCON[i] ^ ((uint32_t) FSb[(RK[3] >> 8) & 0xFF]) ^
                ((uint32_t) FSb[(RK[3] >> 16) & 0xFF] << 8) ^
                ((uint32_t) FSb[(RK[3] >> 24) & 0xFF] << 16) ^
                ((uint32_t) FSb[(RK[3]) & 0xFF] << 24);

        RK[5] = RK[1] ^ RK[4];
        RK[6] = RK[2] ^ RK[5];
        RK[7] = RK[3] ^ RK[6];
      }
      break;

    case 12:
      for (i = 0; i < 8; i++, RK += 6) {
        RK[6] = RK[0] ^ RCON[i] ^ ((uint32_t) FSb[(RK[5] >> 8) & 0xFF]) ^
                ((uint32_t) FSb[(RK[5] >> 16) & 0xFF] << 8) ^
                ((uint32_t) FSb[(RK[5] >> 24) & 0xFF] << 16) ^
                ((uint32_t) FSb[(RK[5]) & 0xFF] << 24);

        RK[7] = RK[1] ^ RK[6];
        RK[8] = RK[2] ^ RK[7];
        RK[9] = RK[3] ^ RK[8];
        RK[10] = RK[4] ^ RK[9];
        RK[11] = RK[5] ^ RK[10];
      }
      break;

    case 14:
      for (i = 0; i < 7; i++, RK += 8) {
        RK[8] = RK[0] ^ RCON[i] ^ ((uint32_t) FSb[(RK[7] >> 8) & 0xFF]) ^
                ((uint32_t) FSb[(RK[7] >> 16) & 0xFF] << 8) ^
                ((uint32_t) FSb[(RK[7] >> 24) & 0xFF] << 16) ^
                ((uint32_t) FSb[(RK[7]) & 0xFF] << 24);

        RK[9] = RK[1] ^ RK[8];
        RK[10] = RK[2] ^ RK[9];
        RK[11] = RK[3] ^ RK[10];

        RK[12] = RK[4] ^ ((uint32_t) FSb[(RK[11]) & 0xFF]) ^
                 ((uint32_t) FSb[(RK[11] >> 8) & 0xFF] << 8) ^
                 ((uint32_t) FSb[(RK[11] >> 16) & 0xFF] << 16) ^
                 ((uint32_t) FSb[(RK[11] >> 24) & 0xFF] << 24);

        RK[13] = RK[5] ^ RK[12];
        RK[14] = RK[6] ^ RK[13];
        RK[15] = RK[7] ^ RK[14];
      }
      break;

    default:
      return -1;
  }
  return (0);
}

#if AES_DECRYPTION  // whether AES decryption is supported

/******************************************************************************
 *
 *  AES_SET_DECRYPTION_KEY
 *
 *  This is called by 'aes_setkey' when we're establishing a
 *  key for subsequent decryption.  We give it a pointer to
 *  the encryption context, a pointer to the key, and the key's
 *  length in bits. Valid lengths are: 128, 192, or 256 bits.
 *
 ******************************************************************************/
static int aes_set_decryption_key(aes_context *ctx, const unsigned char *key,
                                  unsigned int keysize) {
  int i, j;
  aes_context cty;         // a calling aes context for set_encryption_key
  uint32_t *RK = ctx->rk;  // initialize our RoundKey buffer pointer
  uint32_t *SK;
  int ret;

  cty.rounds = ctx->rounds;  // initialize our local aes context
  cty.rk = cty.buf;          // round count and key buf pointer

  if ((ret = aes_set_encryption_key(&cty, key, keysize)) != 0) return (ret);

  SK = cty.rk + cty.rounds * 4;

  CPY128  // copy a 128-bit block from *SK to *RK

      for (i = ctx->rounds - 1, SK -= 8; i > 0; i--, SK -= 8) {
    for (j = 0; j < 4; j++, SK++) {
      *RK++ = RT0[FSb[(*SK) & 0xFF]] ^ RT1[FSb[(*SK >> 8) & 0xFF]] ^
              RT2[FSb[(*SK >> 16) & 0xFF]] ^ RT3[FSb[(*SK >> 24) & 0xFF]];
    }
  }
  CPY128  // copy a 128-bit block from *SK to *RK
      memset(&cty, 0, sizeof(aes_context));  // clear local aes context
  return (0);
}

#endif /* AES_DECRYPTION */

/******************************************************************************
 *
 *  AES_SETKEY
 *
 *  Invoked to establish the key schedule for subsequent encryption/decryption
 *
 ******************************************************************************/
static int aes_setkey(aes_context *ctx,  // AES context provided by our caller
                      int mode,          // ENCRYPT or DECRYPT flag
                      const unsigned char *key,  // pointer to the key
                      unsigned int keysize)      // key length in bytes
{
  // since table initialization is not thread safe, we could either add
  // system-specific mutexes and init the AES key generation tables on
  // demand, or ask the developer to simply call "gcm_initialize" once during
  // application startup before threading begins. That's what we choose.
  if (!aes_tables_inited) return (-1);  // fail the call when not inited.

  ctx->mode = mode;    // capture the key type we're creating
  ctx->rk = ctx->buf;  // initialize our round key pointer

  switch (keysize)  // set the rounds count based upon the keysize
  {
    case 16:
      ctx->rounds = 10;
      break;  // 16-byte, 128-bit key
    case 24:
      ctx->rounds = 12;
      break;  // 24-byte, 192-bit key
    case 32:
      ctx->rounds = 14;
      break;  // 32-byte, 256-bit key
    default:
      return (-1);
  }

#if AES_DECRYPTION
  if (mode == MG_DECRYPT)  // expand our key for encryption or decryption
    return (aes_set_decryption_key(ctx, key, keysize));
  else /* MG_ENCRYPT */
#endif /* AES_DECRYPTION */
    return (aes_set_encryption_key(ctx, key, keysize));
}

/******************************************************************************
 *
 *  AES_CIPHER
 *
 *  Perform AES encryption and decryption.
 *  The AES context will have been setup with the encryption mode
 *  and all keying information appropriate for the task.
 *
 ******************************************************************************/
static int aes_cipher(aes_context *ctx, const unsigned char input[16],
                      unsigned char output[16]) {
  int i;
  uint32_t *RK, X0, X1, X2, X3, Y0, Y1, Y2, Y3;  // general purpose locals

  RK = ctx->rk;

  GET_UINT32_LE(X0, input, 0);
  X0 ^= *RK++;  // load our 128-bit
  GET_UINT32_LE(X1, input, 4);
  X1 ^= *RK++;  // input buffer in a storage
  GET_UINT32_LE(X2, input, 8);
  X2 ^= *RK++;  // memory endian-neutral way
  GET_UINT32_LE(X3, input, 12);
  X3 ^= *RK++;

#if AES_DECRYPTION  // whether AES decryption is supported

  if (ctx->mode == MG_DECRYPT) {
    for (i = (ctx->rounds >> 1) - 1; i > 0; i--) {
      AES_RROUND(Y0, Y1, Y2, Y3, X0, X1, X2, X3);
      AES_RROUND(X0, X1, X2, X3, Y0, Y1, Y2, Y3);
    }

    AES_RROUND(Y0, Y1, Y2, Y3, X0, X1, X2, X3);

    X0 = *RK++ ^ ((uint32_t) RSb[(Y0) & 0xFF]) ^
         ((uint32_t) RSb[(Y3 >> 8) & 0xFF] << 8) ^
         ((uint32_t) RSb[(Y2 >> 16) & 0xFF] << 16) ^
         ((uint32_t) RSb[(Y1 >> 24) & 0xFF] << 24);

    X1 = *RK++ ^ ((uint32_t) RSb[(Y1) & 0xFF]) ^
         ((uint32_t) RSb[(Y0 >> 8) & 0xFF] << 8) ^
         ((uint32_t) RSb[(Y3 >> 16) & 0xFF] << 16) ^
         ((uint32_t) RSb[(Y2 >> 24) & 0xFF] << 24);

    X2 = *RK++ ^ ((uint32_t) RSb[(Y2) & 0xFF]) ^
         ((uint32_t) RSb[(Y1 >> 8) & 0xFF] << 8) ^
         ((uint32_t) RSb[(Y0 >> 16) & 0xFF] << 16) ^
         ((uint32_t) RSb[(Y3 >> 24) & 0xFF] << 24);

    X3 = *RK++ ^ ((uint32_t) RSb[(Y3) & 0xFF]) ^
         ((uint32_t) RSb[(Y2 >> 8) & 0xFF] << 8) ^
         ((uint32_t) RSb[(Y1 >> 16) & 0xFF] << 16) ^
         ((uint32_t) RSb[(Y0 >> 24) & 0xFF] << 24);
  } else /* MG_ENCRYPT */
  {
#endif /* AES_DECRYPTION */

    for (i = (ctx->rounds >> 1) - 1; i > 0; i--) {
      AES_FROUND(Y0, Y1, Y2, Y3, X0, X1, X2, X3);
      AES_FROUND(X0, X1, X2, X3, Y0, Y1, Y2, Y3);
    }

    AES_FROUND(Y0, Y1, Y2, Y3, X0, X1, X2, X3);

    X0 = *RK++ ^ ((uint32_t) FSb[(Y0) & 0xFF]) ^
         ((uint32_t) FSb[(Y1 >> 8) & 0xFF] << 8) ^
         ((uint32_t) FSb[(Y2 >> 16) & 0xFF] << 16) ^
         ((uint32_t) FSb[(Y3 >> 24) & 0xFF] << 24);

    X1 = *RK++ ^ ((uint32_t) FSb[(Y1) & 0xFF]) ^
         ((uint32_t) FSb[(Y2 >> 8) & 0xFF] << 8) ^
         ((uint32_t) FSb[(Y3 >> 16) & 0xFF] << 16) ^
         ((uint32_t) FSb[(Y0 >> 24) & 0xFF] << 24);

    X2 = *RK++ ^ ((uint32_t) FSb[(Y2) & 0xFF]) ^
         ((uint32_t) FSb[(Y3 >> 8) & 0xFF] << 8) ^
         ((uint32_t) FSb[(Y0 >> 16) & 0xFF] << 16) ^
         ((uint32_t) FSb[(Y1 >> 24) & 0xFF] << 24);

    X3 = *RK++ ^ ((uint32_t) FSb[(Y3) & 0xFF]) ^
         ((uint32_t) FSb[(Y0 >> 8) & 0xFF] << 8) ^
         ((uint32_t) FSb[(Y1 >> 16) & 0xFF] << 16) ^
         ((uint32_t) FSb[(Y2 >> 24) & 0xFF] << 24);

#if AES_DECRYPTION  // whether AES decryption is supported
  }
#endif /* AES_DECRYPTION */

  PUT_UINT32_LE(X0, output, 0);
  PUT_UINT32_LE(X1, output, 4);
  PUT_UINT32_LE(X2, output, 8);
  PUT_UINT32_LE(X3, output, 12);

  return (0);
}
/* end of aes.c */
/******************************************************************************
 *
 * THIS SOURCE CODE IS HEREBY PLACED INTO THE PUBLIC DOMAIN FOR THE GOOD OF ALL
 *
 * This is a simple and straightforward implementation of AES-GCM authenticated
 * encryption. The focus of this work was correctness & accuracy. It is written
 * in straight 'C' without any particular focus upon optimization or speed. It
 * should be endian (memory byte order) neutral since the few places that care
 * are handled explicitly.
 *
 * This implementation of AES-GCM was created by Steven M. Gibson of GRC.com.
 *
 * It is intended for general purpose use, but was written in support of GRC's
 * reference implementation of the SQRL (Secure Quick Reliable Login) client.
 *
 * See:    http://csrc.nist.gov/publications/nistpubs/800-38D/SP-800-38D.pdf
 *         http://csrc.nist.gov/groups/ST/toolkit/BCM/documents/proposedmodes/
 *         gcm/gcm-revised-spec.pdf
 *
 * NO COPYRIGHT IS CLAIMED IN THIS WORK, HOWEVER, NEITHER IS ANY WARRANTY MADE
 * REGARDING ITS FITNESS FOR ANY PARTICULAR PURPOSE. USE IT AT YOUR OWN RISK.
 *
 *******************************************************************************/

/******************************************************************************
 *                      ==== IMPLEMENTATION WARNING ====
 *
 *  This code was developed for use within SQRL's fixed environmnent. Thus, it
 *  is somewhat less "general purpose" than it would be if it were designed as
 *  a general purpose AES-GCM library. Specifically, it bothers with almost NO
 *  error checking on parameter limits, buffer bounds, etc. It assumes that it
 *  is being invoked by its author or by someone who understands the values it
 *  expects to receive. Its behavior will be undefined otherwise.
 *
 *  All functions that might fail are defined to return 'ints' to indicate a
 *  problem. Most do not do so now. But this allows for error propagation out
 *  of internal functions if robust error checking should ever be desired.
 *
 ******************************************************************************/

/* Calculating the "GHASH"
 *
 * There are many ways of calculating the so-called GHASH in software, each with
 * a traditional size vs performance tradeoff.  The GHASH (Galois field hash) is
 * an intriguing construction which takes two 128-bit strings (also the cipher's
 * block size and the fundamental operation size for the system) and hashes them
 * into a third 128-bit result.
 *
 * Many implementation solutions have been worked out that use large precomputed
 * table lookups in place of more time consuming bit fiddling, and this approach
 * can be scaled easily upward or downward as needed to change the time/space
 * tradeoff. It's been studied extensively and there's a solid body of theory
 * and practice.  For example, without using any lookup tables an implementation
 * might obtain 119 cycles per byte throughput, whereas using a simple, though
 * large, key-specific 64 kbyte 8-bit lookup table the performance jumps to 13
 * cycles per byte.
 *
 * And Intel's processors have, since 2010, included an instruction which does
 * the entire 128x128->128 bit job in just several 64x64->128 bit pieces.
 *
 * Since SQRL is interactive, and only processing a few 128-bit blocks, I've
 * settled upon a relatively slower but appealing small-table compromise which
 * folds a bunch of not only time consuming but also bit twiddling into a simple
 * 16-entry table which is attributed to Victor Shoup's 1996 work while at
 * Bellcore: "On Fast and Provably Secure MessageAuthentication Based on
 * Universal Hashing."  See: http://www.shoup.net/papers/macs.pdf
 * See, also section 4.1 of the "gcm-revised-spec" cited above.
 */

/*
 *  This 16-entry table of pre-computed constants is used by the
 *  GHASH multiplier to improve over a strictly table-free but
 *  significantly slower 128x128 bit multiple within GF(2^128).
 */
static const uint64_t last4[16] = {
    0x0000, 0x1c20, 0x3840, 0x2460, 0x7080, 0x6ca0, 0x48c0, 0x54e0,
    0xe100, 0xfd20, 0xd940, 0xc560, 0x9180, 0x8da0, 0xa9c0, 0xb5e0};

/*
 * Platform Endianness Neutralizing Load and Store Macro definitions
 * GCM wants platform-neutral Big Endian (BE) byte ordering
 */
#define GET_UINT32_BE(n, b, i)                                            \
  {                                                                       \
    (n) = ((uint32_t) (b)[(i)] << 24) | ((uint32_t) (b)[(i) + 1] << 16) | \
          ((uint32_t) (b)[(i) + 2] << 8) | ((uint32_t) (b)[(i) + 3]);     \
  }

#define PUT_UINT32_BE(n, b, i)          \
  {                                     \
    (b)[(i)] = (unsigned char) ((n) >> 24);     \
    (b)[(i) + 1] = (unsigned char) ((n) >> 16); \
    (b)[(i) + 2] = (unsigned char) ((n) >> 8);  \
    (b)[(i) + 3] = (unsigned char) ((n));       \
  }

/******************************************************************************
 *
 *  GCM_INITIALIZE
 *
 *  Must be called once to initialize the GCM library.
 *
 *  At present, this only calls the AES keygen table generator, which expands
 *  the AES keying tables for use. This is NOT A THREAD-SAFE function, so it
 *  MUST be called during system initialization before a multi-threading
 *  environment is running.
 *
 ******************************************************************************/
int mg_gcm_initialize(void) {
  aes_init_keygen_tables();
  return (0);
}

/******************************************************************************
 *
 *  GCM_MULT
 *
 *  Performs a GHASH operation on the 128-bit input vector 'x', setting
 *  the 128-bit output vector to 'x' times H using our precomputed tables.
 *  'x' and 'output' are seen as elements of GCM's GF(2^128) Galois field.
 *
 ******************************************************************************/
static void gcm_mult(gcm_context *ctx,   // pointer to established context
                     const unsigned char x[16],  // pointer to 128-bit input vector
                     unsigned char output[16])   // pointer to 128-bit output vector
{
  int i;
  unsigned char lo, hi, rem;
  uint64_t zh, zl;

  lo = (unsigned char) (x[15] & 0x0f);
  hi = (unsigned char) (x[15] >> 4);
  zh = ctx->HH[lo];
  zl = ctx->HL[lo];

  for (i = 15; i >= 0; i--) {
    lo = (unsigned char) (x[i] & 0x0f);
    hi = (unsigned char) (x[i] >> 4);

    if (i != 15) {
      rem = (unsigned char) (zl & 0x0f);
      zl = (zh << 60) | (zl >> 4);
      zh = (zh >> 4);
      zh ^= (uint64_t) last4[rem] << 48;
      zh ^= ctx->HH[lo];
      zl ^= ctx->HL[lo];
    }
    rem = (unsigned char) (zl & 0x0f);
    zl = (zh << 60) | (zl >> 4);
    zh = (zh >> 4);
    zh ^= (uint64_t) last4[rem] << 48;
    zh ^= ctx->HH[hi];
    zl ^= ctx->HL[hi];
  }
  PUT_UINT32_BE(zh >> 32, output, 0);
  PUT_UINT32_BE(zh, output, 4);
  PUT_UINT32_BE(zl >> 32, output, 8);
  PUT_UINT32_BE(zl, output, 12);
}

/******************************************************************************
 *
 *  GCM_SETKEY
 *
 *  This is called to set the AES-GCM key. It initializes the AES key
 *  and populates the gcm context's pre-calculated HTables.
 *
 ******************************************************************************/
static int gcm_setkey(
    gcm_context *ctx,    // pointer to caller-provided gcm context
    const unsigned char *key,    // pointer to the AES encryption key
    const unsigned int keysize)  // size in bytes (must be 16, 24, 32 for
                         // 128, 192 or 256-bit keys respectively)
{
  int ret, i, j;
  uint64_t hi, lo;
  uint64_t vl, vh;
  unsigned char h[16];

  memset(ctx, 0, sizeof(gcm_context));  // zero caller-provided GCM context
  memset(h, 0, 16);                     // initialize the block to encrypt

  // encrypt the null 128-bit block to generate a key-based value
  // which is then used to initialize our GHASH lookup tables
  if ((ret = aes_setkey(&ctx->aes_ctx, MG_ENCRYPT, key, keysize)) != 0)
    return (ret);
  if ((ret = aes_cipher(&ctx->aes_ctx, h, h)) != 0) return (ret);

  GET_UINT32_BE(hi, h, 0);  // pack h as two 64-bit ints, big-endian
  GET_UINT32_BE(lo, h, 4);
  vh = (uint64_t) hi << 32 | lo;

  GET_UINT32_BE(hi, h, 8);
  GET_UINT32_BE(lo, h, 12);
  vl = (uint64_t) hi << 32 | lo;

  ctx->HL[8] = vl;  // 8 = 1000 corresponds to 1 in GF(2^128)
  ctx->HH[8] = vh;
  ctx->HH[0] = 0;  // 0 corresponds to 0 in GF(2^128)
  ctx->HL[0] = 0;

  for (i = 4; i > 0; i >>= 1) {
    uint32_t T = (uint32_t) (vl & 1) * 0xe1000000U;
    vl = (vh << 63) | (vl >> 1);
    vh = (vh >> 1) ^ ((uint64_t) T << 32);
    ctx->HL[i] = vl;
    ctx->HH[i] = vh;
  }
  for (i = 2; i < 16; i <<= 1) {
    uint64_t *HiL = ctx->HL + i, *HiH = ctx->HH + i;
    vh = *HiH;
    vl = *HiL;
    for (j = 1; j < i; j++) {
      HiH[j] = vh ^ ctx->HH[j];
      HiL[j] = vl ^ ctx->HL[j];
    }
  }
  return (0);
}

/******************************************************************************
 *
 *    GCM processing occurs four phases: SETKEY, START, UPDATE and FINISH.
 *
 *  SETKEY:
 *
 *   START: Sets the Encryption/Decryption mode.
 *          Accepts the initialization vector and additional data.
 *
 *  UPDATE: Encrypts or decrypts the plaintext or ciphertext.
 *
 *  FINISH: Performs a final GHASH to generate the authentication tag.
 *
 ******************************************************************************
 *
 *  GCM_START
 *
 *  Given a user-provided GCM context, this initializes it, sets the encryption
 *  mode, and preprocesses the initialization vector and additional AEAD data.
 *
 ******************************************************************************/
int gcm_start(gcm_context *ctx,  // pointer to user-provided GCM context
              int mode,          // GCM_ENCRYPT or GCM_DECRYPT
              const unsigned char *iv,   // pointer to initialization vector
              size_t iv_len,     // IV length in bytes (should == 12)
              const unsigned char *add,  // ptr to additional AEAD data (NULL if none)
              size_t add_len)    // length of additional AEAD data (bytes)
{
  int ret;             // our error return if the AES encrypt fails
  unsigned char work_buf[16];  // XOR source built from provided IV if len != 16
  const unsigned char *p;      // general purpose array pointer
  size_t use_len;      // byte count to process, up to 16 bytes
  size_t i;            // local loop iterator

  // since the context might be reused under the same key
  // we zero the working buffers for this next new process
  memset(ctx->y, 0x00, sizeof(ctx->y));
  memset(ctx->buf, 0x00, sizeof(ctx->buf));
  ctx->len = 0;
  ctx->add_len = 0;

  ctx->mode = mode;                // set the GCM encryption/decryption mode
  ctx->aes_ctx.mode = MG_ENCRYPT;  // GCM *always* runs AES in ENCRYPTION mode

  if (iv_len == 12) {            // GCM natively uses a 12-byte, 96-bit IV
    memcpy(ctx->y, iv, iv_len);  // copy the IV to the top of the 'y' buff
    ctx->y[15] = 1;              // start "counting" from 1 (not 0)
  } else  // if we don't have a 12-byte IV, we GHASH whatever we've been given
  {
    memset(work_buf, 0x00, 16);               // clear the working buffer
    PUT_UINT32_BE(iv_len * 8, work_buf, 12);  // place the IV into buffer

    p = iv;
    while (iv_len > 0) {
      use_len = (iv_len < 16) ? iv_len : 16;
      for (i = 0; i < use_len; i++) ctx->y[i] ^= p[i];
      gcm_mult(ctx, ctx->y, ctx->y);
      iv_len -= use_len;
      p += use_len;
    }
    for (i = 0; i < 16; i++) ctx->y[i] ^= work_buf[i];
    gcm_mult(ctx, ctx->y, ctx->y);
  }
  if ((ret = aes_cipher(&ctx->aes_ctx, ctx->y, ctx->base_ectr)) != 0)
    return (ret);

  ctx->add_len = add_len;
  p = add;
  while (add_len > 0) {
    use_len = (add_len < 16) ? add_len : 16;
    for (i = 0; i < use_len; i++) ctx->buf[i] ^= p[i];
    gcm_mult(ctx, ctx->buf, ctx->buf);
    add_len -= use_len;
    p += use_len;
  }
  return (0);
}

/******************************************************************************
 *
 *  GCM_UPDATE
 *
 *  This is called once or more to process bulk plaintext or ciphertext data.
 *  We give this some number of bytes of input and it returns the same number
 *  of output bytes. If called multiple times (which is fine) all but the final
 *  invocation MUST be called with length mod 16 == 0. (Only the final call can
 *  have a partial block length of < 128 bits.)
 *
 ******************************************************************************/
int gcm_update(gcm_context *ctx,    // pointer to user-provided GCM context
               size_t length,       // length, in bytes, of data to process
               const unsigned char *input,  // pointer to source data
               unsigned char *output)       // pointer to destination data
{
  int ret;         // our error return if the AES encrypt fails
  unsigned char ectr[16];  // counter-mode cipher output for XORing
  size_t use_len;  // byte count to process, up to 16 bytes
  size_t i;        // local loop iterator

  ctx->len += length;  // bump the GCM context's running length count

  while (length > 0) {
    // clamp the length to process at 16 bytes
    use_len = (length < 16) ? length : 16;

    // increment the context's 128-bit IV||Counter 'y' vector
    for (i = 16; i > 12; i--)
      if (++ctx->y[i - 1] != 0) break;

    // encrypt the context's 'y' vector under the established key
    if ((ret = aes_cipher(&ctx->aes_ctx, ctx->y, ectr)) != 0) return (ret);

    // encrypt or decrypt the input to the output
    if (ctx->mode == MG_ENCRYPT) {
      for (i = 0; i < use_len; i++) {
        // XOR the cipher's ouptut vector (ectr) with our input
        output[i] = (unsigned char) (ectr[i] ^ input[i]);
        // now we mix in our data into the authentication hash.
        // if we're ENcrypting we XOR in the post-XOR (output)
        // results, but if we're DEcrypting we XOR in the input
        // data
        ctx->buf[i] ^= output[i];
      }
    } else {
      for (i = 0; i < use_len; i++) {
        // but if we're DEcrypting we XOR in the input data first,
        // i.e. before saving to ouput data, otherwise if the input
        // and output buffer are the same (inplace decryption) we
        // would not get the correct auth tag

        ctx->buf[i] ^= input[i];

        // XOR the cipher's ouptut vector (ectr) with our input
        output[i] = (unsigned char) (ectr[i] ^ input[i]);
      }
    }
    gcm_mult(ctx, ctx->buf, ctx->buf);  // perform a GHASH operation

    length -= use_len;  // drop the remaining byte count to process
    input += use_len;   // bump our input pointer forward
    output += use_len;  // bump our output pointer forward
  }
  return (0);
}

/******************************************************************************
 *
 *  GCM_FINISH
 *
 *  This is called once after all calls to GCM_UPDATE to finalize the GCM.
 *  It performs the final GHASH to produce the resulting authentication TAG.
 *
 ******************************************************************************/
int gcm_finish(gcm_context *ctx,  // pointer to user-provided GCM context
               unsigned char *tag,        // pointer to buffer which receives the tag
               size_t tag_len)    // length, in bytes, of the tag-receiving buf
{
  unsigned char work_buf[16];
  uint64_t orig_len = ctx->len * 8;
  uint64_t orig_add_len = ctx->add_len * 8;
  size_t i;

  if (tag_len != 0) memcpy(tag, ctx->base_ectr, tag_len);

  if (orig_len || orig_add_len) {
    memset(work_buf, 0x00, 16);

    PUT_UINT32_BE((orig_add_len >> 32), work_buf, 0);
    PUT_UINT32_BE((orig_add_len), work_buf, 4);
    PUT_UINT32_BE((orig_len >> 32), work_buf, 8);
    PUT_UINT32_BE((orig_len), work_buf, 12);

    for (i = 0; i < 16; i++) ctx->buf[i] ^= work_buf[i];
    gcm_mult(ctx, ctx->buf, ctx->buf);
    for (i = 0; i < tag_len; i++) tag[i] ^= ctx->buf[i];
  }
  return (0);
}

/******************************************************************************
 *
 *  GCM_CRYPT_AND_TAG
 *
 *  This either encrypts or decrypts the user-provided data and, either
 *  way, generates an authentication tag of the requested length. It must be
 *  called with a GCM context whose key has already been set with GCM_SETKEY.
 *
 *  The user would typically call this explicitly to ENCRYPT a buffer of data
 *  and optional associated data, and produce its an authentication tag.
 *
 *  To reverse the process the user would typically call the companion
 *  GCM_AUTH_DECRYPT function to decrypt data and verify a user-provided
 *  authentication tag.  The GCM_AUTH_DECRYPT function calls this function
 *  to perform its decryption and tag generation, which it then compares.
 *
 ******************************************************************************/
int gcm_crypt_and_tag(
    gcm_context *ctx,    // gcm context with key already setup
    int mode,            // cipher direction: GCM_ENCRYPT or GCM_DECRYPT
    const unsigned char *iv,     // pointer to the 12-byte initialization vector
    size_t iv_len,       // byte length if the IV. should always be 12
    const unsigned char *add,    // pointer to the non-ciphered additional data
    size_t add_len,      // byte length of the additional AEAD data
    const unsigned char *input,  // pointer to the cipher data source
    unsigned char *output,       // pointer to the cipher data destination
    size_t length,       // byte length of the cipher data
    unsigned char *tag,          // pointer to the tag to be generated
    size_t tag_len)      // byte length of the tag to be generated
{                        /*
                            assuming that the caller has already invoked gcm_setkey to
                            prepare the gcm context with the keying material, we simply
                            invoke each of the three GCM sub-functions in turn...
                         */
  gcm_start(ctx, mode, iv, iv_len, add, add_len);
  gcm_update(ctx, length, input, output);
  gcm_finish(ctx, tag, tag_len);
  return (0);
}

/******************************************************************************
 *
 *  GCM_ZERO_CTX
 *
 *  The GCM context contains both the GCM context and the AES context.
 *  This includes keying and key-related material which is security-
 *  sensitive, so it MUST be zeroed after use. This function does that.
 *
 ******************************************************************************/
void gcm_zero_ctx(gcm_context *ctx) {
  // zero the context originally provided to us
  memset(ctx, 0, sizeof(gcm_context));
}
//
//  aes-gcm.c
//  Pods
//
//  Created by Markus Kosmal on 20/11/14.
//
//

int mg_aes_gcm_encrypt(unsigned char *output,  //
                       const unsigned char *input, size_t input_length,
                       const unsigned char *key, const size_t key_len,
                       const unsigned char *iv, const size_t iv_len,
                       unsigned char *aead, size_t aead_len, unsigned char *tag,
                       const size_t tag_len) {
  int ret = 0;      // our return value
  gcm_context ctx;  // includes the AES context structure

  gcm_setkey(&ctx, key, (unsigned int) key_len);

  ret = gcm_crypt_and_tag(&ctx, MG_ENCRYPT, iv, iv_len, aead, aead_len, input,
                          output, input_length, tag, tag_len);

  gcm_zero_ctx(&ctx);

  return (ret);
}

int mg_aes_gcm_decrypt(unsigned char *output, const unsigned char *input,
                       size_t input_length, const unsigned char *key,
                       const size_t key_len, const unsigned char *iv,
                       const size_t iv_len) {
  int ret = 0;      // our return value
  gcm_context ctx;  // includes the AES context structure

  size_t tag_len = 0;
  unsigned char *tag_buf = NULL;

  gcm_setkey(&ctx, key, (unsigned int) key_len);

  ret = gcm_crypt_and_tag(&ctx, MG_DECRYPT, iv, iv_len, NULL, 0, input, output,
                          input_length, tag_buf, tag_len);

  gcm_zero_ctx(&ctx);

  return (ret);
}
#endif
// End of aes128 PD

#ifdef MG_ENABLE_LINES
#line 1 "src/tls_builtin.c"
#endif












#if MG_TLS == MG_TLS_BUILTIN

#define CHACHA20 1

/* TLS 1.3 Record Content Type (RFC8446 B.1) */
#define MG_TLS_CHANGE_CIPHER 20
#define MG_TLS_ALERT 21
#define MG_TLS_HANDSHAKE 22
#define MG_TLS_APP_DATA 23
#define MG_TLS_HEARTBEAT 24

/* TLS 1.3 Handshake Message Type (RFC8446 B.3) */
#define MG_TLS_CLIENT_HELLO 1
#define MG_TLS_SERVER_HELLO 2
#define MG_TLS_ENCRYPTED_EXTENSIONS 8
#define MG_TLS_CERTIFICATE 11
#define MG_TLS_CERTIFICATE_REQUEST 13
#define MG_TLS_CERTIFICATE_VERIFY 15
#define MG_TLS_FINISHED 20

// handshake is re-entrant, so we need to keep track of its state state names
// refer to RFC8446#A.1
enum mg_tls_hs_state {
  // Client state machine:
  MG_TLS_STATE_CLIENT_START,          // Send ClientHello
  MG_TLS_STATE_CLIENT_WAIT_SH,        // Wait for ServerHello
  MG_TLS_STATE_CLIENT_WAIT_EE,        // Wait for EncryptedExtensions
  MG_TLS_STATE_CLIENT_WAIT_CERT,      // Wait for Certificate
  MG_TLS_STATE_CLIENT_WAIT_CV,        // Wait for CertificateVerify
  MG_TLS_STATE_CLIENT_WAIT_FINISHED,  // Wait for Finished
  MG_TLS_STATE_CLIENT_CONNECTED,      // Done

  // Server state machine:
  MG_TLS_STATE_SERVER_START,       // Wait for ClientHello
  MG_TLS_STATE_SERVER_NEGOTIATED,  // Wait for Finished
  MG_TLS_STATE_SERVER_CONNECTED    // Done
};

// encryption keys for a TLS connection
struct tls_enc {
  uint32_t sseq;  // server sequence number, used in encryption
  uint32_t cseq;  // client sequence number, used in decryption
  // keys for AES encryption or ChaCha20
  uint8_t handshake_secret[32];
  uint8_t server_write_key[32];
  uint8_t server_write_iv[12];
  uint8_t server_finished_key[32];
  uint8_t client_write_key[32];
  uint8_t client_write_iv[12];
  uint8_t client_finished_key[32];
};

// per-connection TLS data
struct tls_data {
  enum mg_tls_hs_state state;  // keep track of connection handshake progress

  struct mg_iobuf send;  // For the receive path, we're reusing c->rtls
  size_t recv_offset;    // While c->rtls contains full records, reuse that
  size_t recv_len;       // buffer but point at individual decrypted messages

  uint8_t content_type;  // Last received record content type

  mg_sha256_ctx sha256;  // incremental SHA-256 hash for TLS handshake

  uint8_t random[32];      // client random from ClientHello
  uint8_t session_id[32];  // client session ID between the handshake states
  uint8_t x25519_cli[32];  // client X25519 key between the handshake states
  uint8_t x25519_sec[32];  // x25519 secret between the handshake states

  int skip_verification;   // perform checks on server certificate?
  int cert_requested;      // client received a CertificateRequest?
  struct mg_str cert_der;  // certificate in DER format
  struct mg_str ca_der;    // CA certificate
  uint8_t ec_key[32];      // EC private key
  char hostname[254];      // server hostname (client extension)

  int is_ec_pubkey;          // EC or RSA?
  uint8_t pubkey[512 + 16];  // server EC (64) or RSA (512+exp) public key to
                             // verify cert
  size_t pubkeysz;           // size of the server public key
  uint8_t sighash[32];       // calculated signature verification hash

  struct tls_enc enc;
};

#define TLS_RECHDR_SIZE 5  // 1 byte type, 2 bytes version, 2 bytes length
#define TLS_MSGHDR_SIZE 4  // 1 byte type, 3 bytes length

#ifdef MG_TLS_SSLKEYLOGFILE
#include <stdio.h>
static void mg_ssl_key_log(const char *label, uint8_t client_random[32],
                           uint8_t *secret, size_t secretsz) {
  char *keylogfile = getenv("SSLKEYLOGFILE");
  size_t i;
  if (keylogfile != NULL) {
    MG_DEBUG(("Dumping key log into %s", keylogfile));
    FILE *f = fopen(keylogfile, "a");
    if (f != NULL) {
      fprintf(f, "%s ", label);
      for (i = 0; i < 32; i++) {
        fprintf(f, "%02x", client_random[i]);
      }
      fprintf(f, " ");
      for (i = 0; i < secretsz; i++) {
        fprintf(f, "%02x", secret[i]);
      }
      fprintf(f, "\n");
      fclose(f);
    } else {
      MG_ERROR(("Cannot open %s", keylogfile));
    }
  }
}
#endif

// for derived tls keys we need SHA256([0]*32)
static uint8_t zeros[32] = {0};
static uint8_t zeros_sha256_digest[32] = {
    0xe3, 0xb0, 0xc4, 0x42, 0x98, 0xfc, 0x1c, 0x14, 0x9a, 0xfb, 0xf4,
    0xc8, 0x99, 0x6f, 0xb9, 0x24, 0x27, 0xae, 0x41, 0xe4, 0x64, 0x9b,
    0x93, 0x4c, 0xa4, 0x95, 0x99, 0x1b, 0x78, 0x52, 0xb8, 0x55};

// helper to hexdump buffers inline
static void mg_tls_hexdump(const char *msg, uint8_t *buf, size_t bufsz) {
  MG_VERBOSE(("%s: %M", msg, mg_print_hex, bufsz, buf));
}

// helper utilities to parse ASN.1 DER
struct mg_der_tlv {
  uint8_t type;
  uint32_t len;
  uint8_t *value;
};

static int mg_der_parse(uint8_t *der, size_t dersz, struct mg_der_tlv *tlv) {
  size_t header_len = 2;
  uint32_t len = dersz < 2 ? 0 : der[1];
  if (dersz < 2) return -1;  // Invalid DER
  tlv->type = der[0];
  if (len > 0x7F) {  // long-form length
    uint8_t len_bytes = len & 0x7F;
    if (dersz < (size_t) (2 + len_bytes)) return -1;
    len = 0;
    for (uint8_t i = 0; i < len_bytes; i++) {
      len = (len << 8) | der[2 + i];
    }
    header_len += len_bytes;
  }
  if (dersz < header_len + len) return -1;
  tlv->len = len;
  tlv->value = der + header_len;
  return (int) (header_len + len);
}

static int mg_der_next(struct mg_der_tlv *parent, struct mg_der_tlv *child) {
  if (parent->len == 0) return 0;
  int consumed = mg_der_parse(parent->value, parent->len, child);
  if (consumed < 0) return -1;
  parent->value += consumed;
  parent->len -= (uint32_t) consumed;
  return 1;
}

static int mg_der_find_oid(struct mg_der_tlv *tlv, const uint8_t *oid,
                           size_t oid_len, struct mg_der_tlv *found) {
  struct mg_der_tlv parent, child;
  parent = *tlv;
  while (mg_der_next(&parent, &child) > 0) {
    if (child.type == 0x06 && child.len == oid_len &&
        memcmp(child.value, oid, oid_len) == 0) {
      return mg_der_next(&parent, found);
    } else if (child.type & 0x20) {
      struct mg_der_tlv sub_parent = child;
      if (mg_der_find_oid(&sub_parent, oid, oid_len, found)) return 1;
    }
  }
  return 0;
}

#if 0
static void mg_der_debug(struct mg_der_tlv *tlv, int depth) {
  MG_DEBUG(("> %.*sd=%d Type: 0x%02X, Length: %u\n", depth * 4, " ", depth,
            tlv->type, tlv->len));

  if (tlv->type & 0x20) {  // Constructed: recurse into children
    struct mg_der_tlv child;
    struct mg_der_tlv parent = *tlv;
    while (mg_der_next(&parent, &child) > 0) {
      mg_der_debug(&child, depth + 1);
    }
  }
}
#endif

// parse DER into a TLV record
static int mg_der_to_tlv(uint8_t *der, size_t dersz, struct mg_der_tlv *tlv) {
  if (dersz < 2) {
    return -1;
  }
  tlv->type = der[0];
  tlv->len = der[1];
  tlv->value = der + 2;
  if (tlv->len > 0x7f) {
    uint32_t i, n = tlv->len - 0x80;
    tlv->len = 0;
    for (i = 0; i < n; i++) {
      tlv->len = (tlv->len << 8) | (der[2 + i]);
    }
    tlv->value = der + 2 + n;
  }
  if (der + dersz < tlv->value + tlv->len) {
    return -1;
  }
  return 0;
}

// Did we receive a full TLS record in the c->rtls buffer?
static bool mg_tls_got_record(struct mg_connection *c) {
  return c->rtls.len >= (size_t) TLS_RECHDR_SIZE &&
         c->rtls.len >=
             (size_t) (TLS_RECHDR_SIZE + MG_LOAD_BE16(c->rtls.buf + 3));
}

// Remove a single TLS record from the recv buffer
static void mg_tls_drop_record(struct mg_connection *c) {
  struct mg_iobuf *rio = &c->rtls;
  uint16_t n = MG_LOAD_BE16(rio->buf + 3) + TLS_RECHDR_SIZE;
  mg_iobuf_del(rio, 0, n);
}

// Remove a single TLS message from decrypted buffer, remove the wrapping
// record if it was the last message within a record
static void mg_tls_drop_message(struct mg_connection *c) {
  uint32_t len;
  struct tls_data *tls = (struct tls_data *) c->tls;
  unsigned char *recv_buf = &c->rtls.buf[tls->recv_offset];
  if (tls->recv_len == 0) return;
  len = MG_LOAD_BE24(recv_buf + 1) + TLS_MSGHDR_SIZE;
  if (tls->recv_len < len) {
    mg_error(c, "wrong size");
    return;
  }
  mg_sha256_update(&tls->sha256, recv_buf, len);
  tls->recv_offset += len;
  tls->recv_len -= len;
  if (tls->recv_len == 0) {
    mg_tls_drop_record(c);
  }
}

// TLS1.3 secret derivation based on the key label
static void mg_tls_derive_secret(const char *label, uint8_t *key, size_t keysz,
                                 uint8_t *data, size_t datasz, uint8_t *hash,
                                 size_t hashsz) {
  size_t labelsz = strlen(label);
  uint8_t secret[32];
  uint8_t packed[256] = {0, (uint8_t) hashsz, (uint8_t) labelsz};
  // TODO: assert lengths of label, key, data and hash
  if (labelsz > 0) memmove(packed + 3, label, labelsz);
  packed[3 + labelsz] = (uint8_t) datasz;
  if (datasz > 0) memmove(packed + labelsz + 4, data, datasz);
  packed[4 + labelsz + datasz] = 1;

  mg_hmac_sha256(secret, key, keysz, packed, 5 + labelsz + datasz);
  memmove(hash, secret, hashsz);
}

// at this point we have x25519 shared secret, we can generate a set of derived
// handshake encryption keys
static void mg_tls_generate_handshake_keys(struct mg_connection *c) {
  struct tls_data *tls = (struct tls_data *) c->tls;

  mg_sha256_ctx sha256;
  uint8_t early_secret[32];
  uint8_t pre_extract_secret[32];
  uint8_t hello_hash[32];
  uint8_t server_hs_secret[32];
  uint8_t client_hs_secret[32];
#if CHACHA20
  const size_t keysz = 32;
#else
  const size_t keysz = 16;
#endif

  mg_hmac_sha256(early_secret, NULL, 0, zeros, sizeof(zeros));
  mg_tls_derive_secret("tls13 derived", early_secret, 32, zeros_sha256_digest,
                       32, pre_extract_secret, 32);
  mg_hmac_sha256(tls->enc.handshake_secret, pre_extract_secret,
                 sizeof(pre_extract_secret), tls->x25519_sec,
                 sizeof(tls->x25519_sec));
  mg_tls_hexdump("hs secret", tls->enc.handshake_secret, 32);

  // mg_sha256_final is not idempotent, need to copy sha256 context to calculate
  // the digest
  memmove(&sha256, &tls->sha256, sizeof(mg_sha256_ctx));
  mg_sha256_final(hello_hash, &sha256);

  mg_tls_hexdump("hello hash", hello_hash, 32);
  // derive keys needed for the rest of the handshake
  mg_tls_derive_secret("tls13 s hs traffic", tls->enc.handshake_secret, 32,
                       hello_hash, 32, server_hs_secret, 32);
  mg_tls_derive_secret("tls13 c hs traffic", tls->enc.handshake_secret, 32,
                       hello_hash, 32, client_hs_secret, 32);

  mg_tls_derive_secret("tls13 key", server_hs_secret, 32, NULL, 0,
                       tls->enc.server_write_key, keysz);
  mg_tls_derive_secret("tls13 iv", server_hs_secret, 32, NULL, 0,
                       tls->enc.server_write_iv, 12);
  mg_tls_derive_secret("tls13 finished", server_hs_secret, 32, NULL, 0,
                       tls->enc.server_finished_key, 32);

  mg_tls_derive_secret("tls13 key", client_hs_secret, 32, NULL, 0,
                       tls->enc.client_write_key, keysz);
  mg_tls_derive_secret("tls13 iv", client_hs_secret, 32, NULL, 0,
                       tls->enc.client_write_iv, 12);
  mg_tls_derive_secret("tls13 finished", client_hs_secret, 32, NULL, 0,
                       tls->enc.client_finished_key, 32);

  mg_tls_hexdump("s hs traffic", server_hs_secret, 32);
  mg_tls_hexdump("s key", tls->enc.server_write_key, keysz);
  mg_tls_hexdump("s iv", tls->enc.server_write_iv, 12);
  mg_tls_hexdump("s finished", tls->enc.server_finished_key, 32);
  mg_tls_hexdump("c hs traffic", client_hs_secret, 32);
  mg_tls_hexdump("c key", tls->enc.client_write_key, keysz);
  mg_tls_hexdump("c iv", tls->enc.client_write_iv, 12);
  mg_tls_hexdump("c finished", tls->enc.client_finished_key, 32);

#ifdef MG_TLS_SSLKEYLOGFILE
  mg_ssl_key_log("SERVER_HANDSHAKE_TRAFFIC_SECRET", tls->random,
                 server_hs_secret, 32);
  mg_ssl_key_log("CLIENT_HANDSHAKE_TRAFFIC_SECRET", tls->random,
                 client_hs_secret, 32);
#endif
}

static void mg_tls_generate_application_keys(struct mg_connection *c) {
  struct tls_data *tls = (struct tls_data *) c->tls;
  uint8_t hash[32];
  uint8_t premaster_secret[32];
  uint8_t master_secret[32];
  uint8_t server_secret[32];
  uint8_t client_secret[32];
#if CHACHA20
  const size_t keysz = 32;
#else
  const size_t keysz = 16;
#endif

  mg_sha256_ctx sha256;
  memmove(&sha256, &tls->sha256, sizeof(mg_sha256_ctx));
  mg_sha256_final(hash, &sha256);

  mg_tls_derive_secret("tls13 derived", tls->enc.handshake_secret, 32,
                       zeros_sha256_digest, 32, premaster_secret, 32);
  mg_hmac_sha256(master_secret, premaster_secret, 32, zeros, 32);

  mg_tls_derive_secret("tls13 s ap traffic", master_secret, 32, hash, 32,
                       server_secret, 32);
  mg_tls_derive_secret("tls13 key", server_secret, 32, NULL, 0,
                       tls->enc.server_write_key, keysz);
  mg_tls_derive_secret("tls13 iv", server_secret, 32, NULL, 0,
                       tls->enc.server_write_iv, 12);
  mg_tls_derive_secret("tls13 c ap traffic", master_secret, 32, hash, 32,
                       client_secret, 32);
  mg_tls_derive_secret("tls13 key", client_secret, 32, NULL, 0,
                       tls->enc.client_write_key, keysz);
  mg_tls_derive_secret("tls13 iv", client_secret, 32, NULL, 0,
                       tls->enc.client_write_iv, 12);

  mg_tls_hexdump("s ap traffic", server_secret, 32);
  mg_tls_hexdump("s key", tls->enc.server_write_key, keysz);
  mg_tls_hexdump("s iv", tls->enc.server_write_iv, 12);
  mg_tls_hexdump("s finished", tls->enc.server_finished_key, 32);
  mg_tls_hexdump("c ap traffic", client_secret, 32);
  mg_tls_hexdump("c key", tls->enc.client_write_key, keysz);
  mg_tls_hexdump("c iv", tls->enc.client_write_iv, 12);
  mg_tls_hexdump("c finished", tls->enc.client_finished_key, 32);
  tls->enc.sseq = tls->enc.cseq = 0;

#ifdef MG_TLS_SSLKEYLOGFILE
  mg_ssl_key_log("SERVER_TRAFFIC_SECRET_0", tls->random, server_secret, 32);
  mg_ssl_key_log("CLIENT_TRAFFIC_SECRET_0", tls->random, client_secret, 32);
#endif
}

// AES GCM encryption of the message + put encoded data into the write buffer
static void mg_tls_encrypt(struct mg_connection *c, const uint8_t *msg,
                           size_t msgsz, uint8_t msgtype) {
  struct tls_data *tls = (struct tls_data *) c->tls;
  struct mg_iobuf *wio = &tls->send;
  uint8_t *outmsg;
  uint8_t *tag;
  size_t encsz = msgsz + 16 + 1;
  uint8_t hdr[5] = {MG_TLS_APP_DATA, 0x03, 0x03,
                    (uint8_t) ((encsz >> 8) & 0xff), (uint8_t) (encsz & 0xff)};
  uint8_t associated_data[5] = {MG_TLS_APP_DATA, 0x03, 0x03,
                                (uint8_t) ((encsz >> 8) & 0xff),
                                (uint8_t) (encsz & 0xff)};
  uint8_t nonce[12];

  uint32_t seq = c->is_client ? tls->enc.cseq : tls->enc.sseq;
  uint8_t *key =
      c->is_client ? tls->enc.client_write_key : tls->enc.server_write_key;
  uint8_t *iv =
      c->is_client ? tls->enc.client_write_iv : tls->enc.server_write_iv;

#if !CHACHA20
  mg_gcm_initialize();
#endif

  memmove(nonce, iv, sizeof(nonce));
  nonce[8] ^= (uint8_t) ((seq >> 24) & 255U);
  nonce[9] ^= (uint8_t) ((seq >> 16) & 255U);
  nonce[10] ^= (uint8_t) ((seq >> 8) & 255U);
  nonce[11] ^= (uint8_t) ((seq) &255U);

  mg_iobuf_add(wio, wio->len, hdr, sizeof(hdr));
  mg_iobuf_resize(wio, wio->len + encsz);
  outmsg = wio->buf + wio->len;
  tag = wio->buf + wio->len + msgsz + 1;
  memmove(outmsg, msg, msgsz);
  outmsg[msgsz] = msgtype;
#if CHACHA20
  (void) tag;  // tag is only used in aes gcm
  {
    size_t maxlen = MG_IO_SIZE > 16384 ? 16384 : MG_IO_SIZE;
    uint8_t *enc = (uint8_t *) calloc(1, maxlen + 256 + 1);
    if (enc == NULL) {
      mg_error(c, "TLS OOM");
      return;
    } else {
      size_t n = mg_chacha20_poly1305_encrypt(enc, key, nonce, associated_data,
                                              sizeof(associated_data), outmsg,
                                              msgsz + 1);
      memmove(outmsg, enc, n);
      free(enc);
    }
  }
#else
  mg_aes_gcm_encrypt(outmsg, outmsg, msgsz + 1, key, 16, nonce, sizeof(nonce),
                     associated_data, sizeof(associated_data), tag, 16);
#endif
  c->is_client ? tls->enc.cseq++ : tls->enc.sseq++;
  wio->len += encsz;
}

// read an encrypted record, decrypt it in place
static int mg_tls_recv_record(struct mg_connection *c) {
  struct tls_data *tls = (struct tls_data *) c->tls;
  struct mg_iobuf *rio = &c->rtls;
  uint16_t msgsz;
  uint8_t *msg;
  uint8_t nonce[12];
  int r;

  uint32_t seq = c->is_client ? tls->enc.sseq : tls->enc.cseq;
  uint8_t *key =
      c->is_client ? tls->enc.server_write_key : tls->enc.client_write_key;
  uint8_t *iv =
      c->is_client ? tls->enc.server_write_iv : tls->enc.client_write_iv;

  if (tls->recv_len > 0) {
    return 0; /* some data from previous record is still present */
  }
  for (;;) {
    if (!mg_tls_got_record(c)) {
      return MG_IO_WAIT;
    }
    if (rio->buf[0] == MG_TLS_APP_DATA) {
      break;
    } else if (rio->buf[0] ==
               MG_TLS_CHANGE_CIPHER) {  // Skip ChangeCipher messages
      mg_tls_drop_record(c);
    } else if (rio->buf[0] == MG_TLS_ALERT) {  // Skip Alerts
      MG_INFO(("TLS ALERT packet received"));
      mg_tls_drop_record(c);
    } else {
      mg_error(c, "unexpected packet");
      return -1;
    }
  }

  msgsz = MG_LOAD_BE16(rio->buf + 3);
  msg = rio->buf + 5;
  if (msgsz < 16) {
    mg_error(c, "wrong size");
    return -1;
  }

  memmove(nonce, iv, sizeof(nonce));
  nonce[8] ^= (uint8_t) ((seq >> 24) & 255U);
  nonce[9] ^= (uint8_t) ((seq >> 16) & 255U);
  nonce[10] ^= (uint8_t) ((seq >> 8) & 255U);
  nonce[11] ^= (uint8_t) ((seq) &255U);
#if CHACHA20
  {
    uint8_t *dec = (uint8_t *) calloc(1, msgsz);
    size_t n;
    if (dec == NULL) {
      mg_error(c, "TLS OOM");
      return -1;
    }
    n = mg_chacha20_poly1305_decrypt(dec, key, nonce, msg, msgsz);
    memmove(msg, dec, n);
    free(dec);
  }
#else
  mg_gcm_initialize();
  mg_aes_gcm_decrypt(msg, msg, msgsz - 16, key, 16, nonce, sizeof(nonce));
#endif

  r = msgsz - 16 - 1;
  tls->content_type = msg[msgsz - 16 - 1];
  tls->recv_offset = (size_t) msg - (size_t) rio->buf;
  tls->recv_len = (size_t) msgsz - 16 - 1;
  c->is_client ? tls->enc.sseq++ : tls->enc.cseq++;
  return r;
}

static void mg_tls_calc_cert_verify_hash(struct mg_connection *c,
                                         uint8_t hash[32], int is_client) {
  struct tls_data *tls = (struct tls_data *) c->tls;
  uint8_t server_context[34] = "TLS 1.3, server CertificateVerify";
  uint8_t client_context[34] = "TLS 1.3, client CertificateVerify";
  uint8_t sig_content[130];
  mg_sha256_ctx sha256;

  memset(sig_content, 0x20, 64);
  if (is_client) {
    memmove(sig_content + 64, client_context, sizeof(client_context));
  } else {
    memmove(sig_content + 64, server_context, sizeof(server_context));
  }

  memmove(&sha256, &tls->sha256, sizeof(mg_sha256_ctx));
  mg_sha256_final(sig_content + 98, &sha256);

  mg_sha256_init(&sha256);
  mg_sha256_update(&sha256, sig_content, sizeof(sig_content));
  mg_sha256_final(hash, &sha256);
}

// read and parse ClientHello record
static int mg_tls_server_recv_hello(struct mg_connection *c) {
  struct tls_data *tls = (struct tls_data *) c->tls;
  struct mg_iobuf *rio = &c->rtls;
  uint8_t session_id_len;
  uint16_t j;
  uint16_t cipher_suites_len;
  uint16_t ext_len;
  uint8_t *ext;
  uint16_t msgsz;

  if (!mg_tls_got_record(c)) {
    return MG_IO_WAIT;
  }
  if (rio->buf[0] != MG_TLS_HANDSHAKE || rio->buf[5] != MG_TLS_CLIENT_HELLO) {
    mg_error(c, "not a client hello packet");
    return -1;
  }
  msgsz = MG_LOAD_BE16(rio->buf + 3);
  mg_sha256_update(&tls->sha256, rio->buf + 5, msgsz);
  // store client random
  memmove(tls->random, rio->buf + 11, sizeof(tls->random));
  // store session_id
  session_id_len = rio->buf[43];
  if (session_id_len == sizeof(tls->session_id)) {
    memmove(tls->session_id, rio->buf + 44, session_id_len);
  } else if (session_id_len != 0) {
    MG_INFO(("bad session id len"));
  }
  cipher_suites_len = MG_LOAD_BE16(rio->buf + 44 + session_id_len);
  if (cipher_suites_len > (rio->len - 46 - session_id_len)) goto fail;
  ext_len = MG_LOAD_BE16(rio->buf + 48 + session_id_len + cipher_suites_len);
  ext = rio->buf + 50 + session_id_len + cipher_suites_len;
  if (ext_len > (rio->len - 50 - session_id_len - cipher_suites_len)) goto fail;
  for (j = 0; j < ext_len;) {
    uint16_t k;
    uint16_t key_exchange_len;
    uint8_t *key_exchange;
    uint16_t n = MG_LOAD_BE16(ext + j + 2);
    if (MG_LOAD_BE16(ext + j) != 0x0033) {  // not a key share extension, ignore
      j += (uint16_t) (n + 4);
      continue;
    }
    key_exchange_len = MG_LOAD_BE16(ext + j + 4);
    key_exchange = ext + j + 6;
    if (key_exchange_len >
        rio->len - (uint16_t) ((size_t) key_exchange - (size_t) rio->buf))
      goto fail;
    for (k = 0; k < key_exchange_len;) {
      uint16_t m = MG_LOAD_BE16(key_exchange + k + 2);
      if (m > (key_exchange_len - k - 4)) goto fail;
      if (m == 32 && key_exchange[k] == 0x00 && key_exchange[k + 1] == 0x1d) {
        memmove(tls->x25519_cli, key_exchange + k + 4, m);
        mg_tls_drop_record(c);
        return 0;
      }
      k += (uint16_t) (m + 4);
    }
    j += (uint16_t) (n + 4);
  }
fail:
  mg_error(c, "bad client hello");
  return -1;
}

#define PLACEHOLDER_8B 'X', 'X', 'X', 'X', 'X', 'X', 'X', 'X'
#define PLACEHOLDER_16B PLACEHOLDER_8B, PLACEHOLDER_8B
#define PLACEHOLDER_32B PLACEHOLDER_16B, PLACEHOLDER_16B

// put ServerHello record into wio buffer
static void mg_tls_server_send_hello(struct mg_connection *c) {
  struct tls_data *tls = (struct tls_data *) c->tls;
  struct mg_iobuf *wio = &tls->send;

  // clang-format off
  uint8_t msg_server_hello[122] = {
      // server hello, tls 1.2
      0x02, 0x00, 0x00, 0x76, 0x03, 0x03,
      // random (32 bytes)
      PLACEHOLDER_32B,
      // session ID length + session ID (32 bytes)
      0x20, PLACEHOLDER_32B,
#if defined(CHACHA20) && CHACHA20
      // TLS_CHACHA20_POLY1305_SHA256 + no compression
      0x13, 0x03, 0x00,
#else
      // TLS_AES_128_GCM_SHA256 + no compression
      0x13, 0x01, 0x00,
#endif
      // extensions + keyshare
      0x00, 0x2e, 0x00, 0x33, 0x00, 0x24, 0x00, 0x1d, 0x00, 0x20,
      // x25519 keyshare
      PLACEHOLDER_32B,
      // supported versions (tls1.3 == 0x304)
      0x00, 0x2b, 0x00, 0x02, 0x03, 0x04};
  // clang-format on

  // calculate keyshare
  uint8_t x25519_pub[X25519_BYTES];
  uint8_t x25519_prv[X25519_BYTES];
  if (!mg_random(x25519_prv, sizeof(x25519_prv))) mg_error(c, "RNG");
  mg_tls_x25519(x25519_pub, x25519_prv, X25519_BASE_POINT, 1);
  mg_tls_x25519(tls->x25519_sec, x25519_prv, tls->x25519_cli, 1);
  mg_tls_hexdump("s x25519 sec", tls->x25519_sec, sizeof(tls->x25519_sec));

  // fill in the gaps: random + session ID + keyshare
  memmove(msg_server_hello + 6, tls->random, sizeof(tls->random));
  memmove(msg_server_hello + 39, tls->session_id, sizeof(tls->session_id));
  memmove(msg_server_hello + 84, x25519_pub, sizeof(x25519_pub));

  // server hello message
  mg_iobuf_add(wio, wio->len, "\x16\x03\x03\x00\x7a", 5);
  mg_iobuf_add(wio, wio->len, msg_server_hello, sizeof(msg_server_hello));
  mg_sha256_update(&tls->sha256, msg_server_hello, sizeof(msg_server_hello));

  // change cipher message
  mg_iobuf_add(wio, wio->len, "\x14\x03\x03\x00\x01\x01", 6);
}

static void mg_tls_server_send_ext(struct mg_connection *c) {
  struct tls_data *tls = (struct tls_data *) c->tls;
  // server extensions
  uint8_t ext[6] = {0x08, 0, 0, 2, 0, 0};
  mg_sha256_update(&tls->sha256, ext, sizeof(ext));
  mg_tls_encrypt(c, ext, sizeof(ext), MG_TLS_HANDSHAKE);
}

static void mg_tls_server_send_cert(struct mg_connection *c) {
  struct tls_data *tls = (struct tls_data *) c->tls;
  int send_ca = !c->is_client && tls->ca_der.len > 0;
  // server DER certificate + CA (optional)
  size_t n = tls->cert_der.len + (send_ca ? tls->ca_der.len + 5 : 0);
  uint8_t *cert = (uint8_t *) calloc(1, 13 + n);
  if (cert == NULL) {
    mg_error(c, "tls cert oom");
    return;
  }
  cert[0] = 0x0b;  // handshake header
  MG_STORE_BE24(cert + 1, n + 9);
  cert[4] = 0;                                 // request context
  MG_STORE_BE24(cert + 5, n + 5);              // 3 bytes: cert (s) length
  MG_STORE_BE24(cert + 8, tls->cert_der.len);  // 3 bytes: first cert len
  // bytes 11+ are certificate in DER format
  memmove(cert + 11, tls->cert_der.buf, tls->cert_der.len);
  MG_STORE_BE16(cert + 11 + tls->cert_der.len,
                0);  // certificate extensions (none)
  if (send_ca) {
    size_t offset = 13 + tls->cert_der.len;
    MG_STORE_BE24(cert + offset, tls->ca_der.len);  // 3 bytes: CA cert length
    memmove(cert + offset + 3, tls->ca_der.buf,
            tls->ca_der.len);         // CA cert data
    MG_STORE_BE16(cert + 11 + n, 0);  // certificate extensions (none)
  }
  mg_sha256_update(&tls->sha256, cert, 13 + n);
  mg_tls_encrypt(c, cert, 13 + n, MG_TLS_HANDSHAKE);
  free(cert);
}

// type adapter between uECC hash context and our sha256 implementation
typedef struct SHA256_HashContext {
  MG_UECC_HashContext uECC;
  mg_sha256_ctx ctx;
} SHA256_HashContext;

static void init_SHA256(const MG_UECC_HashContext *base) {
  SHA256_HashContext *c = (SHA256_HashContext *) base;
  mg_sha256_init(&c->ctx);
}

static void update_SHA256(const MG_UECC_HashContext *base,
                          const uint8_t *message, unsigned message_size) {
  SHA256_HashContext *c = (SHA256_HashContext *) base;
  mg_sha256_update(&c->ctx, message, message_size);
}
static void finish_SHA256(const MG_UECC_HashContext *base,
                          uint8_t *hash_result) {
  SHA256_HashContext *c = (SHA256_HashContext *) base;
  mg_sha256_final(hash_result, &c->ctx);
}

static void mg_tls_send_cert_verify(struct mg_connection *c, int is_client) {
  struct tls_data *tls = (struct tls_data *) c->tls;
  // server certificate verify packet
  uint8_t verify[82] = {0x0f, 0x00, 0x00, 0x00, 0x04, 0x03, 0x00, 0x00};
  size_t sigsz, verifysz = 0;
  uint8_t hash[32] = {0}, tmp[2 * 32 + 64] = {0};
  struct SHA256_HashContext ctx = {
      {&init_SHA256, &update_SHA256, &finish_SHA256, 64, 32, tmp},
      {{0}, 0, 0, {0}}};
  int neg1, neg2;
  uint8_t sig[64] = {0};

  mg_tls_calc_cert_verify_hash(c, (uint8_t *) hash, is_client);

  mg_uecc_sign_deterministic(tls->ec_key, hash, sizeof(hash), &ctx.uECC, sig,
                             mg_uecc_secp256r1());

  neg1 = !!(sig[0] & 0x80);
  neg2 = !!(sig[32] & 0x80);
  verify[8] = 0x30;  // ASN.1 SEQUENCE
  verify[9] = (uint8_t) (68 + neg1 + neg2);
  verify[10] = 0x02;  // ASN.1 INTEGER
  verify[11] = (uint8_t) (32 + neg1);
  memmove(verify + 12 + neg1, sig, 32);
  verify[12 + 32 + neg1] = 0x02;  // ASN.1 INTEGER
  verify[13 + 32 + neg1] = (uint8_t) (32 + neg2);
  memmove(verify + 14 + 32 + neg1 + neg2, sig + 32, 32);

  sigsz = (size_t) (70 + neg1 + neg2);
  verifysz = 8U + sigsz;
  verify[3] = (uint8_t) (sigsz + 4);
  verify[7] = (uint8_t) sigsz;

  mg_sha256_update(&tls->sha256, verify, verifysz);
  mg_tls_encrypt(c, verify, verifysz, MG_TLS_HANDSHAKE);
}

static void mg_tls_server_send_finish(struct mg_connection *c) {
  struct tls_data *tls = (struct tls_data *) c->tls;
  struct mg_iobuf *wio = &tls->send;
  mg_sha256_ctx sha256;
  uint8_t hash[32];
  uint8_t finish[36] = {0x14, 0, 0, 32};
  memmove(&sha256, &tls->sha256, sizeof(mg_sha256_ctx));
  mg_sha256_final(hash, &sha256);
  mg_hmac_sha256(finish + 4, tls->enc.server_finished_key, 32, hash, 32);
  mg_tls_encrypt(c, finish, sizeof(finish), MG_TLS_HANDSHAKE);
  mg_io_send(c, wio->buf, wio->len);
  wio->len = 0;

  mg_sha256_update(&tls->sha256, finish, sizeof(finish));
}

static int mg_tls_server_recv_finish(struct mg_connection *c) {
  struct tls_data *tls = (struct tls_data *) c->tls;
  unsigned char *recv_buf;
  // we have to backup sha256 value to restore it later, since Finished record
  // is exceptional and is not supposed to be added to the rolling hash
  // calculation.
  mg_sha256_ctx sha256 = tls->sha256;
  if (mg_tls_recv_record(c) < 0) {
    return -1;
  }
  recv_buf = &c->rtls.buf[tls->recv_offset];
  if (recv_buf[0] != MG_TLS_FINISHED) {
    mg_error(c, "expected Finish but got msg 0x%02x", recv_buf[0]);
    return -1;
  }
  mg_tls_drop_message(c);

  // restore hash
  tls->sha256 = sha256;
  return 0;
}

static void mg_tls_client_send_hello(struct mg_connection *c) {
  struct tls_data *tls = (struct tls_data *) c->tls;
  struct mg_iobuf *wio = &tls->send;

  uint8_t x25519_pub[X25519_BYTES];

  // signature algorithms we actually support:
  // rsa_pkcs1_sha256, rsa_pss_rsae_sha256 and ecdsa_secp256r1_sha256
  uint8_t secp256r1_sig_algs[12] = {
      0x00, 0x0d, 0x00, 0x08, 0x00, 0x06, 0x04, 0x03, 0x08, 0x04, 0x04, 0x01,
  };
  // all popular signature algorithms (if we don't care about verification)
  uint8_t all_sig_algs[34] = {
      0x00, 0x0d, 0x00, 0x1e, 0x00, 0x1c, 0x04, 0x03, 0x05, 0x03, 0x06, 0x03,
      0x08, 0x07, 0x08, 0x08, 0x08, 0x09, 0x08, 0x0a, 0x08, 0x0b, 0x08, 0x04,
      0x08, 0x05, 0x08, 0x06, 0x04, 0x01, 0x05, 0x01, 0x06, 0x01};
  uint8_t server_name_ext[9] = {0x00, 0x00, 0x00, 0xfe, 0x00,
                                0xfe, 0x00, 0x00, 0xfe};

  // clang-format off
  uint8_t msg_client_hello[145] = {
      // TLS Client Hello header reported as TLS1.2 (5)
      0x16, 0x03, 0x03, 0x00, 0xfe,
      // client hello, tls 1.2 (6)
      0x01, 0x00, 0x00, 0x8c, 0x03, 0x03,
      // random (32 bytes)
      PLACEHOLDER_32B,
      // session ID length + session ID (32 bytes)
      0x20, PLACEHOLDER_32B, 0x00,
      0x02,  // size = 2 bytes
#if defined(CHACHA20) && CHACHA20
      // TLS_CHACHA20_POLY1305_SHA256
      0x13, 0x03,
#else
      // TLS_AES_128_GCM_SHA256
      0x13, 0x01,
#endif
      // no compression
      0x01, 0x00,
      // extensions + keyshare
      0x00, 0xfe,
      // x25519 keyshare
      0x00, 0x33, 0x00, 0x26, 0x00, 0x24, 0x00, 0x1d, 0x00, 0x20,
      PLACEHOLDER_32B,
      // supported groups (x25519)
      0x00, 0x0a, 0x00, 0x04, 0x00, 0x02, 0x00, 0x1d,
      // supported versions (tls1.3 == 0x304)
      0x00, 0x2b, 0x00, 0x03, 0x02, 0x03, 0x04,
      // session ticket (none)
      0x00, 0x23, 0x00, 0x00, // 144 bytes till here
	};
  // clang-format on
  const char *hostname = tls->hostname;
  size_t hostnamesz = strlen(tls->hostname);
  size_t hostname_extsz = hostnamesz ? hostnamesz + 9 : 0;
  uint8_t *sig_alg = tls->skip_verification ? all_sig_algs : secp256r1_sig_algs;
  size_t sig_alg_sz = tls->skip_verification ? sizeof(all_sig_algs)
                                             : sizeof(secp256r1_sig_algs);

  // patch ClientHello with correct hostname ext length (if any)
  MG_STORE_BE16(msg_client_hello + 3,
                hostname_extsz + 183 - 9 - 34 + sig_alg_sz);
  MG_STORE_BE16(msg_client_hello + 7,
                hostname_extsz + 179 - 9 - 34 + sig_alg_sz);
  MG_STORE_BE16(msg_client_hello + 82,
                hostname_extsz + 104 - 9 - 34 + sig_alg_sz);

  if (hostnamesz > 0) {
    MG_STORE_BE16(server_name_ext + 2, hostnamesz + 5);
    MG_STORE_BE16(server_name_ext + 4, hostnamesz + 3);
    MG_STORE_BE16(server_name_ext + 7, hostnamesz);
  }

  // calculate keyshare
  if (!mg_random(tls->x25519_cli, sizeof(tls->x25519_cli))) mg_error(c, "RNG");
  mg_tls_x25519(x25519_pub, tls->x25519_cli, X25519_BASE_POINT, 1);

  // fill in the gaps: random + session ID + keyshare
  if (!mg_random(tls->session_id, sizeof(tls->session_id))) mg_error(c, "RNG");
  if (!mg_random(tls->random, sizeof(tls->random))) mg_error(c, "RNG");
  memmove(msg_client_hello + 11, tls->random, sizeof(tls->random));
  memmove(msg_client_hello + 44, tls->session_id, sizeof(tls->session_id));
  memmove(msg_client_hello + 94, x25519_pub, sizeof(x25519_pub));

  // client hello message
  mg_iobuf_add(wio, wio->len, msg_client_hello, sizeof(msg_client_hello));
  mg_sha256_update(&tls->sha256, msg_client_hello + 5,
                   sizeof(msg_client_hello) - 5);
  mg_iobuf_add(wio, wio->len, sig_alg, sig_alg_sz);
  mg_sha256_update(&tls->sha256, sig_alg, sig_alg_sz);
  if (hostnamesz > 0) {
    mg_iobuf_add(wio, wio->len, server_name_ext, sizeof(server_name_ext));
    mg_iobuf_add(wio, wio->len, hostname, hostnamesz);
    mg_sha256_update(&tls->sha256, server_name_ext, sizeof(server_name_ext));
    mg_sha256_update(&tls->sha256, (uint8_t *) hostname, hostnamesz);
  }

  // change cipher message
  mg_iobuf_add(wio, wio->len, (const char *) "\x14\x03\x03\x00\x01\x01", 6);
  mg_io_send(c, wio->buf, wio->len);
  wio->len = 0;
}

static int mg_tls_client_recv_hello(struct mg_connection *c) {
  struct tls_data *tls = (struct tls_data *) c->tls;
  struct mg_iobuf *rio = &c->rtls;
  uint16_t msgsz;
  uint8_t *ext;
  uint16_t ext_len;
  int j;

  if (!mg_tls_got_record(c)) {
    return MG_IO_WAIT;
  }
  if (rio->buf[0] != MG_TLS_HANDSHAKE || rio->buf[5] != MG_TLS_SERVER_HELLO) {
    if (rio->buf[0] == MG_TLS_ALERT && rio->len >= 7) {
      mg_error(c, "tls alert %d", rio->buf[6]);
      return -1;
    }
    MG_INFO(("got packet type 0x%02x/0x%02x", rio->buf[0], rio->buf[5]));
    mg_error(c, "not a server hello packet");
    return -1;
  }

  msgsz = MG_LOAD_BE16(rio->buf + 3);
  mg_sha256_update(&tls->sha256, rio->buf + 5, msgsz);

  ext_len = MG_LOAD_BE16(rio->buf + 5 + 39 + 32 + 3);
  ext = rio->buf + 5 + 39 + 32 + 3 + 2;
  if (ext_len > (rio->len - (5 + 39 + 32 + 3 + 2))) goto fail;

  for (j = 0; j < ext_len;) {
    uint16_t ext_type = MG_LOAD_BE16(ext + j);
    uint16_t ext_len2 = MG_LOAD_BE16(ext + j + 2);
    uint16_t group;
    uint8_t *key_exchange;
    uint16_t key_exchange_len;
    if (ext_len2 > (ext_len - j - 4)) goto fail;
    if (ext_type != 0x0033) {  // not a key share extension, ignore
      j += (uint16_t) (ext_len2 + 4);
      continue;
    }
    group = MG_LOAD_BE16(ext + j + 4);
    if (group != 0x001d) {
      mg_error(c, "bad key exchange group");
      return -1;
    }
    key_exchange_len = MG_LOAD_BE16(ext + j + 6);
    key_exchange = ext + j + 8;
    if (key_exchange_len != 32) {
      mg_error(c, "bad key exchange length");
      return -1;
    }
    mg_tls_x25519(tls->x25519_sec, tls->x25519_cli, key_exchange, 1);
    mg_tls_hexdump("c x25519 sec", tls->x25519_sec, 32);
    mg_tls_drop_record(c);
    /* generate handshake keys */
    mg_tls_generate_handshake_keys(c);
    return 0;
  }
fail:
  mg_error(c, "bad server hello");
  return -1;
}

static int mg_tls_client_recv_ext(struct mg_connection *c) {
  struct tls_data *tls = (struct tls_data *) c->tls;
  unsigned char *recv_buf;
  if (mg_tls_recv_record(c) < 0) {
    return -1;
  }
  recv_buf = &c->rtls.buf[tls->recv_offset];
  if (recv_buf[0] != MG_TLS_ENCRYPTED_EXTENSIONS) {
    mg_error(c, "expected server extensions but got msg 0x%02x", recv_buf[0]);
    return -1;
  }
  mg_tls_drop_message(c);
  return 0;
}

struct mg_tls_cert {
  int is_ec_pubkey;
  struct mg_str sn;
  struct mg_str pubkey;
  struct mg_str sig;    // signature
  uint8_t tbshash[48];  // 32b for sha256/secp256, 48b for sha384/secp384
  size_t tbshashsz;     // actual TBS hash size
};

static void mg_der_debug_cert_name(const char *name, struct mg_der_tlv *tlv) {
  struct mg_der_tlv v;
  struct mg_str cn, c, o, ou;
  cn = c = o = ou = mg_str("");
  if (mg_der_find_oid(tlv, (uint8_t *) "\x55\x04\x03", 3, &v))
    cn = mg_str_n((const char *) v.value, v.len);
  if (mg_der_find_oid(tlv, (uint8_t *) "\x55\x04\x06", 3, &v))
    c = mg_str_n((const char *) v.value, v.len);
  if (mg_der_find_oid(tlv, (uint8_t *) "\x55\x04\x0a", 3, &v))
    o = mg_str_n((const char *) v.value, v.len);
  if (mg_der_find_oid(tlv, (uint8_t *) "\x55\x04\x0b", 3, &v))
    ou = mg_str_n((const char *) v.value, v.len);
  MG_VERBOSE(("%s: CN=%.*s, C=%.*s, O=%.*s, OU=%.*s", name, cn.len, cn.buf,
              c.len, c.buf, o.len, o.buf, ou.len, ou.buf));
}

static int mg_tls_parse_cert_der(void *buf, size_t dersz,
                                 struct mg_tls_cert *cert) {
  uint8_t *tbs, *der = (uint8_t *) buf;
  size_t tbssz;
  struct mg_der_tlv root, tbs_cert, field, algo;  // pubkey, signature;
  struct mg_der_tlv pki, pki_algo, pki_key, pki_curve, raw_sig;

  // Parse outermost SEQUENCE
  if (mg_der_parse(der, dersz, &root) <= 0 || root.type != 0x30) return -1;

  // Parse TBSCertificate SEQUENCE
  tbs = root.value;
  if (mg_der_next(&root, &tbs_cert) <= 0 || tbs_cert.type != 0x30) return -1;
  tbssz = (size_t) (tbs_cert.value + tbs_cert.len - tbs);

  // Parse Version (optional field)
  if (mg_der_next(&tbs_cert, &field) <= 0) return -1;
  if (field.type == 0xa0) {  // v3
    if (mg_der_parse(field.value, field.len, &field) <= 0 || field.len != 1 ||
        field.value[0] != 2)
      return -1;
    if (mg_der_next(&tbs_cert, &field) <= 0) return -1;
  }

  // Parse Serial Number
  if (field.type != 2) return -1;
  cert->sn = mg_str_n((char *) field.value, field.len);
  MG_VERBOSE(("cert s/n: %M", mg_print_hex, cert->sn.len, cert->sn.buf));

  // Parse signature algorithm (first occurrence)
  if (mg_der_next(&tbs_cert, &field) <= 0 || field.type != 0x30) return -1;
  if (mg_der_next(&field, &algo) <= 0 || algo.type != 0x06) return -1;

  MG_VERBOSE(("sig algo (oid): %M", mg_print_hex, algo.len, algo.value));
  // Signature algorithm OID mapping
  if (memcmp(algo.value, "\x2A\x86\x48\xCE\x3D\x04\x03\x02", algo.len) == 0) {
    MG_VERBOSE(("sig algo: ECDSA with SHA256"));
    mg_sha256(cert->tbshash, tbs, tbssz);
    cert->tbshashsz = 32;
  } else if (memcmp(algo.value, "\x2A\x86\x48\x86\xF7\x0D\x01\x01\x0B",
                    algo.len) == 0) {
    MG_VERBOSE(("sig algo: RSA with SHA256"));
    mg_sha256(cert->tbshash, tbs, tbssz);
    cert->tbshashsz = 32;
  } else if (memcmp(algo.value, "\x2A\x86\x48\xCE\x3D\x04\x03\x03", algo.len) ==
             0) {
    MG_VERBOSE(("sig algo: ECDSA with SHA384"));
    mg_sha384(cert->tbshash, tbs, tbssz);
    cert->tbshashsz = 48;
  } else if (memcmp(algo.value, "\x2A\x86\x48\x86\xF7\x0D\x01\x01\x0C",
                    algo.len) == 0) {
    MG_VERBOSE(("sig algo: RSA with SHA384"));
    mg_sha384(cert->tbshash, tbs, tbssz);
    cert->tbshashsz = 48;
  } else {
    MG_ERROR(
        ("sig algo: unsupported OID: %M", mg_print_hex, algo.len, algo.value));
    return -1;
  }
  MG_VERBOSE(("tbs hash: %M", mg_print_hex, cert->tbshashsz, cert->tbshash));

  // issuer
  if (mg_der_next(&tbs_cert, &field) <= 0 || field.type != 0x30) return -1;
  mg_der_debug_cert_name("issuer", &field);

  // validity dates (before/after)
  if (mg_der_next(&tbs_cert, &field) <= 0 || field.type != 0x30) return -1;
  if (1) {
    struct mg_der_tlv before, after;
    mg_der_next(&field, &before);
    mg_der_next(&field, &after);
    if (memcmp(after.value, "250101000000Z", after.len) < 0) {
      MG_ERROR(("invalid validity dates: before=%M after=%M", mg_print_hex,
                before.len, before.value, mg_print_hex, after.len,
                after.value));
      return -1;
    }
  }

  // subject
  if (mg_der_next(&tbs_cert, &field) <= 0 || field.type != 0x30) return -1;
  mg_der_debug_cert_name("subject", &field);

  // subject public key info
  if (mg_der_next(&tbs_cert, &field) <= 0 || field.type != 0x30) return -1;

  if (mg_der_next(&field, &pki) <= 0 || pki.type != 0x30) return -1;
  if (mg_der_next(&pki, &pki_algo) <= 0 || pki_algo.type != 0x06) return -1;

  // public key algorithm
  MG_VERBOSE(("pk algo (oid): %M", mg_print_hex, pki_algo.len, pki_algo.value));
  if (memcmp(pki_algo.value, "\x2A\x86\x48\xCE\x3D\x03\x01\x07",
             pki_algo.len) == 0) {
    cert->is_ec_pubkey = 1;
    MG_VERBOSE(("pk algo: ECDSA secp256r1"));
  } else if (memcmp(pki_algo.value, "\x2A\x86\x48\xCE\x3D\x03\x01\x08",
                    pki_algo.len) == 0) {
    cert->is_ec_pubkey = 1;
    MG_VERBOSE(("pk algo: ECDSA secp384r1"));
  } else if (memcmp(pki_algo.value, "\x2A\x86\x48\xCE\x3D\x02\x01",
                    pki_algo.len) == 0) {
    cert->is_ec_pubkey = 1;
    MG_VERBOSE(("pk algo: EC public key"));
  } else if (memcmp(pki_algo.value, "\x2A\x86\x48\x86\xF7\x0D\x01\x01\x01",
                    pki_algo.len) == 0) {
    cert->is_ec_pubkey = 0;
    MG_VERBOSE(("pk algo: RSA"));
  } else {
    MG_ERROR(("unsupported pk algo: %M", mg_print_hex, pki_algo.len,
              pki_algo.value));
    return -1;
  }

  // Parse public key
  if (cert->is_ec_pubkey) {
    if (mg_der_next(&pki, &pki_curve) <= 0 || pki_curve.type != 0x06) return -1;
  }
  if (mg_der_next(&field, &pki_key) <= 0 || pki_key.type != 0x03) return -1;

  if (cert->is_ec_pubkey) {  // Skip leading 0x00 and 0x04 (=uncompressed)
    cert->pubkey = mg_str_n((char *) pki_key.value + 2, pki_key.len - 2);
  } else {  // Skip leading 0x00 byte
    cert->pubkey = mg_str_n((char *) pki_key.value + 1, pki_key.len - 1);
  }

  // Parse signature
  if (mg_der_next(&root, &field) <= 0 || field.type != 0x30) return -1;
  if (mg_der_next(&root, &raw_sig) <= 0 || raw_sig.type != 0x03) return -1;
  if (raw_sig.len < 1 || raw_sig.value[0] != 0x00) return -1;

  cert->sig = mg_str_n((char *) raw_sig.value + 1, raw_sig.len - 1);
  MG_VERBOSE(("sig: %M", mg_print_hex, cert->sig.len, cert->sig.buf));

  return 0;
}

static int mg_tls_verify_cert_san(const uint8_t *der, size_t dersz,
                                  const char *server_name) {
  struct mg_der_tlv root, field, name;
  if (mg_der_parse((uint8_t *) der, dersz, &root) < 0 ||
      mg_der_find_oid(&root, (uint8_t *) "\x55\x1d\x11", 3, &field) < 0) {
    MG_ERROR(("failed to parse certificate to extract SAN"));
    return -1;
  }
  if (mg_der_parse(field.value, field.len, &field) < 0) {
    MG_ERROR(
        ("certificate subject alternative names is not a constructed object"));
    return -1;
  }
  while (mg_der_next(&field, &name) > 0) {
    if (mg_match(mg_str(server_name),
                 mg_str_n((const char *) name.value, name.len), NULL)) {
      // Found SAN that matches the host name
      return 1;
    }
  }
  return -1;
}

static int mg_tls_verify_cert_signature(const struct mg_tls_cert *cert,
                                        const struct mg_tls_cert *issuer) {
  if (issuer->is_ec_pubkey) {
    uint8_t sig[128];
    struct mg_der_tlv seq = {0, 0, 0}, a = {0, 0, 0}, b = {0, 0, 0};
    mg_der_parse((uint8_t *) cert->sig.buf, cert->sig.len, &seq);
    mg_der_next(&seq, &a);
    mg_der_next(&seq, &b);
    if (a.len == 0 || b.len == 0) {
      MG_ERROR(("cert verification error"));
      return 0;
    }
    if (issuer->pubkey.len == 64) {
      const uint32_t N = 32;
      if (a.len > N) a.value += (a.len - N), a.len = N;
      if (b.len > N) b.value += (b.len - N), b.len = N;
      memmove(sig, a.value, N);
      memmove(sig + N, b.value, N);
      return mg_uecc_verify((uint8_t *) issuer->pubkey.buf, cert->tbshash,
                            (unsigned) cert->tbshashsz, sig,
                            mg_uecc_secp256r1());
    } else if (issuer->pubkey.len == 96) {
      MG_DEBUG(("ignore secp386 for now"));
      return 1;
    } else {
      MG_ERROR(("unsupported public key length: %d", issuer->pubkey.len));
      return 0;
    }
  } else {
    int r;
    uint8_t sig2[256];  // 2048 bits
    struct mg_der_tlv seq, modulus, exponent;
    if (mg_der_parse((uint8_t *) issuer->pubkey.buf, issuer->pubkey.len,
                     &seq) <= 0 ||
        mg_der_next(&seq, &modulus) <= 0 || modulus.type != 2 ||
        mg_der_next(&seq, &exponent) <= 0 || exponent.type != 2) {
      return -1;
    }
    mg_rsa_mod_pow(modulus.value, modulus.len, exponent.value, exponent.len,
                   (uint8_t *) cert->sig.buf, cert->sig.len, sig2,
                   sizeof(sig2));

    r = memcmp(sig2 + sizeof(sig2) - cert->tbshashsz, cert->tbshash,
               cert->tbshashsz);
    return r == 0;
  }
}

static int mg_tls_client_recv_cert(struct mg_connection *c) {
  int subj_match = 0;
  struct tls_data *tls = (struct tls_data *) c->tls;
  unsigned char *recv_buf;
  (void) subj_match;

  if (mg_tls_recv_record(c) < 0) {
    return -1;
  }

  recv_buf = &c->rtls.buf[tls->recv_offset];

  if (recv_buf[0] == MG_TLS_CERTIFICATE_REQUEST) {
    MG_VERBOSE(("got certificate request"));
    mg_tls_drop_message(c);
    tls->cert_requested = 1;
    return -1;
  }

  if (recv_buf[0] != MG_TLS_CERTIFICATE) {
    mg_error(c, "expected server certificate but got msg 0x%02x", recv_buf[0]);
    return -1;
  }

  if (tls->recv_len < 11) {
    mg_error(c, "certificate list too short");
    return -1;
  }

  uint32_t full_cert_chain_len = MG_LOAD_BE24(recv_buf + 1);
  uint32_t cert_chain_len = MG_LOAD_BE24(recv_buf + 5);
  if (cert_chain_len != full_cert_chain_len - 4) {
    MG_ERROR(("full chain length: %d, chain length: %d", full_cert_chain_len,
              cert_chain_len));
    mg_error(c, "certificate chain length mismatch");
    return -1;
  }

  // Normally, there are 2-3 certs in a chain
  struct mg_tls_cert certs[8];
  int certnum = 0;
  uint8_t *p = recv_buf + 8;
  // uint8_t *endp = recv_buf + tls->recv_len;
  uint8_t *endp = recv_buf + cert_chain_len;

  int found_ca = 0;
  struct mg_tls_cert ca;

  memset(certs, 0, sizeof(certs));
  memset(&ca, 0, sizeof(ca));

  if (tls->ca_der.len > 0) {
    if (mg_tls_parse_cert_der(tls->ca_der.buf, tls->ca_der.len, &ca) < 0) {
      mg_error(c, "failed to parse CA certificate");
      return -1;
    }
    MG_VERBOSE(("CA serial: %M", mg_print_hex, ca.sn.len, ca.sn.buf));
  }

  while (p < endp) {
    struct mg_tls_cert *ci = &certs[certnum++];
    uint32_t certsz = MG_LOAD_BE24(p);
    uint8_t *cert = p + 3;
    uint16_t certext = MG_LOAD_BE16(cert + certsz);
    if (certext != 0) {
      mg_error(c, "certificate extensions are not supported");
      return -1;
    }
    p = cert + certsz + 2;

    if (mg_tls_parse_cert_der(cert, certsz, ci) < 0) {
      mg_error(c, "failed to parse certificate");
      return -1;
    }

    if (ci == certs) {
      // First certificate in the chain is peer cert, check SAN and store
      // public key for further CertVerify step
      if (mg_tls_verify_cert_san(cert, certsz, tls->hostname) <= 0) {
        mg_error(c, "failed to verify hostname");
        return -1;
      }
      memmove(tls->pubkey, ci->pubkey.buf, ci->pubkey.len);
      tls->pubkeysz = ci->pubkey.len;
    } else {
      if (!mg_tls_verify_cert_signature(ci - 1, ci)) {
        mg_error(c, "failed to verify certificate chain");
        return -1;
      }
    }

    if (ca.pubkey.len == ci->pubkey.len &&
        memcmp(ca.pubkey.buf, ci->pubkey.buf, ca.pubkey.len) == 0) {
      found_ca = 1;
      break;
    }

    if (certnum == sizeof(certs) / sizeof(certs[0]) - 1) {
      mg_error(c, "too many certificates in the chain");
      return -1;
    }
  }

  if (!found_ca && tls->ca_der.len > 0) {
    if (certnum < 1 ||
        !mg_tls_verify_cert_signature(&certs[certnum - 1], &ca)) {
      mg_error(c, "failed to verify CA");
      return -1;
    } else {
      MG_VERBOSE(
          ("CA was not in the chain, but verification with builtin CA passed"));
    }
  }

  mg_tls_drop_message(c);
  mg_tls_calc_cert_verify_hash(c, tls->sighash, 0);
  return 0;
}

static int mg_tls_client_recv_cert_verify(struct mg_connection *c) {
  struct tls_data *tls = (struct tls_data *) c->tls;
  unsigned char *recv_buf;
  if (mg_tls_recv_record(c) < 0) {
    return -1;
  }
  recv_buf = &c->rtls.buf[tls->recv_offset];
  if (recv_buf[0] != MG_TLS_CERTIFICATE_VERIFY) {
    mg_error(c, "expected server certificate verify but got msg 0x%02x",
             recv_buf[0]);
    return -1;
  }
  if (tls->recv_len < 8) {
    mg_error(c, "server certificate verify is too short: %d bytes",
             tls->recv_len);
    return -1;
  }

  // Ignore CertificateVerify is strict checks are not required
  if (tls->skip_verification) {
    mg_tls_drop_message(c);
    return 0;
  }

  uint16_t sigalg = MG_LOAD_BE16(recv_buf + 4);
  uint16_t siglen = MG_LOAD_BE16(recv_buf + 6);
  uint8_t *sigbuf = recv_buf + 8;
  if (siglen > tls->recv_len - 8) {
    mg_error(c, "invalid certverify signature length: %d, expected %d", siglen,
             tls->recv_len - 8);
    return -1;
  }
  MG_VERBOSE(
      ("certificate verification, algo=%04x, siglen=%d", sigalg, siglen));

  if (sigalg == 0x0804) {  // rsa_pss_rsae_sha256
    uint8_t sig2[512];     // 2048 or 4096 bits
    struct mg_der_tlv seq, modulus, exponent;

    if (mg_der_parse(tls->pubkey, tls->pubkeysz, &seq) <= 0 ||
        mg_der_next(&seq, &modulus) <= 0 || modulus.type != 2 ||
        mg_der_next(&seq, &exponent) <= 0 || exponent.type != 2) {
      mg_error(c, "invalid public key");
      return -1;
    }

    mg_rsa_mod_pow(modulus.value, modulus.len, exponent.value, exponent.len,
                   sigbuf, siglen, sig2, sizeof(sig2));

    if (sig2[sizeof(sig2) - 1] != 0xbc) {
      mg_error(c, "failed to verify RSA certificate (certverify)");
      return -1;
    }
    MG_DEBUG(("certificate verification successful (RSA)"));
  } else if (sigalg == 0x0403) {  // ecdsa_secp256r1_sha256
    // Extract certificate signature and verify it using pubkey and sighash
    uint8_t sig[64];
    struct mg_der_tlv seq, r, s;
    if (mg_der_to_tlv(sigbuf, siglen, &seq) < 0) {
      mg_error(c, "verification message is not an ASN.1 DER sequence");
      return -1;
    }
    if (mg_der_to_tlv(seq.value, seq.len, &r) < 0) {
      mg_error(c, "missing first part of the signature");
      return -1;
    }
    if (mg_der_to_tlv(r.value + r.len, seq.len - r.len, &s) < 0) {
      mg_error(c, "missing second part of the signature");
      return -1;
    }
    // Integers may be padded with zeroes
    if (r.len > 32) r.value = r.value + (r.len - 32), r.len = 32;
    if (s.len > 32) s.value = s.value + (s.len - 32), s.len = 32;

    memmove(sig, r.value, r.len);
    memmove(sig + 32, s.value, s.len);

    if (mg_uecc_verify(tls->pubkey, tls->sighash, sizeof(tls->sighash), sig,
                       mg_uecc_secp256r1()) != 1) {
      mg_error(c, "failed to verify EC certificate (certverify)");
      return -1;
    }
    MG_DEBUG(("certificate verification successful (EC)"));
  } else {
    // From
    // https://www.iana.org/assignments/tls-parameters/tls-parameters.xhtml:
    //   0805 = rsa_pss_rsae_sha384
    //   0806 = rsa_pss_rsae_sha512
    //   0807 = ed25519
    //   0808 = ed448
    //   0809 = rsa_pss_pss_sha256
    //   080A = rsa_pss_pss_sha384
    //   080B = rsa_pss_pss_sha512
    MG_ERROR(("unsupported certverify signature scheme: %x of %d bytes", sigalg,
              siglen));
    return -1;
  }
  mg_tls_drop_message(c);
  return 0;
}

static int mg_tls_client_recv_finish(struct mg_connection *c) {
  struct tls_data *tls = (struct tls_data *) c->tls;
  unsigned char *recv_buf;
  if (mg_tls_recv_record(c) < 0) {
    return -1;
  }
  recv_buf = &c->rtls.buf[tls->recv_offset];
  if (recv_buf[0] != MG_TLS_FINISHED) {
    mg_error(c, "expected server finished but got msg 0x%02x", recv_buf[0]);
    return -1;
  }
  mg_tls_drop_message(c);
  return 0;
}

static void mg_tls_client_send_finish(struct mg_connection *c) {
  struct tls_data *tls = (struct tls_data *) c->tls;
  struct mg_iobuf *wio = &tls->send;
  mg_sha256_ctx sha256;
  uint8_t hash[32];
  uint8_t finish[36] = {0x14, 0, 0, 32};
  memmove(&sha256, &tls->sha256, sizeof(mg_sha256_ctx));
  mg_sha256_final(hash, &sha256);
  mg_hmac_sha256(finish + 4, tls->enc.client_finished_key, 32, hash, 32);
  mg_tls_encrypt(c, finish, sizeof(finish), MG_TLS_HANDSHAKE);
  mg_io_send(c, wio->buf, wio->len);
  wio->len = 0;
}

static void mg_tls_client_handshake(struct mg_connection *c) {
  struct tls_data *tls = (struct tls_data *) c->tls;
  switch (tls->state) {
    case MG_TLS_STATE_CLIENT_START:
      mg_tls_client_send_hello(c);
      tls->state = MG_TLS_STATE_CLIENT_WAIT_SH;
      // Fallthrough
    case MG_TLS_STATE_CLIENT_WAIT_SH:
      if (mg_tls_client_recv_hello(c) < 0) {
        break;
      }
      tls->state = MG_TLS_STATE_CLIENT_WAIT_EE;
      // Fallthrough
    case MG_TLS_STATE_CLIENT_WAIT_EE:
      if (mg_tls_client_recv_ext(c) < 0) {
        break;
      }
      tls->state = MG_TLS_STATE_CLIENT_WAIT_CERT;
      // Fallthrough
    case MG_TLS_STATE_CLIENT_WAIT_CERT:
      if (mg_tls_client_recv_cert(c) < 0) {
        break;
      }
      tls->state = MG_TLS_STATE_CLIENT_WAIT_CV;
      // Fallthrough
    case MG_TLS_STATE_CLIENT_WAIT_CV:
      if (mg_tls_client_recv_cert_verify(c) < 0) {
        break;
      }
      tls->state = MG_TLS_STATE_CLIENT_WAIT_FINISHED;
      // Fallthrough
    case MG_TLS_STATE_CLIENT_WAIT_FINISHED:
      if (mg_tls_client_recv_finish(c) < 0) {
        break;
      }
      if (tls->cert_requested) {
        /* for mTLS we should generate application keys at this point
         * but then restore handshake keys and continue with
         * the rest of the handshake */
        struct tls_enc app_keys;
        struct tls_enc hs_keys = tls->enc;
        mg_tls_generate_application_keys(c);
        app_keys = tls->enc;
        tls->enc = hs_keys;
        mg_tls_server_send_cert(c);
        mg_tls_send_cert_verify(c, 1);
        mg_tls_client_send_finish(c);
        tls->enc = app_keys;
      } else {
        mg_tls_client_send_finish(c);
        mg_tls_generate_application_keys(c);
      }
      tls->state = MG_TLS_STATE_CLIENT_CONNECTED;
      c->is_tls_hs = 0;
      mg_call(c, MG_EV_TLS_HS, NULL);
      break;
    default:
      mg_error(c, "unexpected client state: %d", tls->state);
      break;
  }
}

static void mg_tls_server_handshake(struct mg_connection *c) {
  struct tls_data *tls = (struct tls_data *) c->tls;
  switch (tls->state) {
    case MG_TLS_STATE_SERVER_START:
      if (mg_tls_server_recv_hello(c) < 0) {
        return;
      }
      mg_tls_server_send_hello(c);
      mg_tls_generate_handshake_keys(c);
      mg_tls_server_send_ext(c);
      mg_tls_server_send_cert(c);
      mg_tls_send_cert_verify(c, 0);
      mg_tls_server_send_finish(c);
      tls->state = MG_TLS_STATE_SERVER_NEGOTIATED;
      // fallthrough
    case MG_TLS_STATE_SERVER_NEGOTIATED:
      if (mg_tls_server_recv_finish(c) < 0) {
        return;
      }
      mg_tls_generate_application_keys(c);
      tls->state = MG_TLS_STATE_SERVER_CONNECTED;
      c->is_tls_hs = 0;
      return;
    default:
      mg_error(c, "unexpected server state: %d", tls->state);
      break;
  }
}

void mg_tls_handshake(struct mg_connection *c) {
  if (c->is_client) {
    mg_tls_client_handshake(c);
  } else {
    mg_tls_server_handshake(c);
  }
}

static int mg_parse_pem(const struct mg_str pem, const struct mg_str label,
                        struct mg_str *der) {
  size_t n = 0, m = 0;
  char *s;
  const char *c;
  struct mg_str caps[6];  // number of wildcards + 1
  if (!mg_match(pem, mg_str("#-----BEGIN #-----#-----END #-----#"), caps)) {
    *der = mg_strdup(pem);
    return 0;
  }
  if (mg_strcmp(caps[1], label) != 0 || mg_strcmp(caps[3], label) != 0) {
    return -1;  // bad label
  }
  if ((s = (char *) calloc(1, caps[2].len)) == NULL) {
    return -1;
  }

  for (c = caps[2].buf; c < caps[2].buf + caps[2].len; c++) {
    if (*c == ' ' || *c == '\n' || *c == '\r' || *c == '\t') {
      continue;
    }
    s[n++] = *c;
  }
  m = mg_base64_decode(s, n, s, n);
  if (m == 0) {
    free(s);
    return -1;
  }
  der->buf = s;
  der->len = m;
  return 0;
}

void mg_tls_init(struct mg_connection *c, const struct mg_tls_opts *opts) {
  struct mg_str key;
  struct tls_data *tls = (struct tls_data *) calloc(1, sizeof(struct tls_data));
  if (tls == NULL) {
    mg_error(c, "tls oom");
    return;
  }

  tls->state =
      c->is_client ? MG_TLS_STATE_CLIENT_START : MG_TLS_STATE_SERVER_START;

  tls->skip_verification = opts->skip_verification;
  // tls->send.align = MG_IO_SIZE;

  c->tls = tls;
  c->is_tls = c->is_tls_hs = 1;
  mg_sha256_init(&tls->sha256);

  // save hostname (client extension)
  if (opts->name.len > 0) {
    if (opts->name.len >= sizeof(tls->hostname) - 1) {
      mg_error(c, "hostname too long");
      return;
    }
    strncpy((char *) tls->hostname, opts->name.buf, sizeof(tls->hostname) - 1);
    tls->hostname[opts->name.len] = 0;
  }
  // server CA certificate, store serial number
  if (opts->ca.len > 0) {
    if (mg_parse_pem(opts->ca, mg_str_s("CERTIFICATE"), &tls->ca_der) < 0) {
      MG_ERROR(("Failed to load certificate"));
      return;
    }
  }

  if (opts->cert.buf == NULL) {
    MG_VERBOSE(("No certificate provided"));
    return;
  }

  // parse PEM or DER certificate
  if (mg_parse_pem(opts->cert, mg_str_s("CERTIFICATE"), &tls->cert_der) < 0) {
    MG_ERROR(("Failed to load certificate"));
    return;
  }

  // parse PEM or DER EC key
  if (opts->key.buf == NULL) {
    mg_error(c, "Certificate provided without a private key");
    return;
  }

  if (mg_parse_pem(opts->key, mg_str_s("EC PRIVATE KEY"), &key) == 0) {
    if (key.len < 39) {
      MG_ERROR(("EC private key too short"));
      return;
    }
    // expect ASN.1 SEQUENCE=[INTEGER=1, BITSTRING of 32 bytes, ...]
    // 30 nn 02 01 01 04 20 [key] ...
    if (key.buf[0] != 0x30 || (key.buf[1] & 0x80) != 0) {
      MG_ERROR(("EC private key: ASN.1 bad sequence"));
      return;
    }
    if (memcmp(key.buf + 2, "\x02\x01\x01\x04\x20", 5) != 0) {
      MG_ERROR(("EC private key: ASN.1 bad data"));
    }
    memmove(tls->ec_key, key.buf + 7, 32);
    free((void *) key.buf);
  } else if (mg_parse_pem(opts->key, mg_str_s("PRIVATE KEY"), &key) == 0) {
    mg_error(c, "PKCS8 private key format is not supported");
  } else {
    mg_error(c, "Expected EC PRIVATE KEY or PRIVATE KEY");
  }
}

void mg_tls_free(struct mg_connection *c) {
  struct tls_data *tls = (struct tls_data *) c->tls;
  if (tls != NULL) {
    mg_iobuf_free(&tls->send);
    free((void *) tls->cert_der.buf);
    free((void *) tls->ca_der.buf);
  }
  free(c->tls);
  c->tls = NULL;
}

long mg_tls_send(struct mg_connection *c, const void *buf, size_t len) {
  struct tls_data *tls = (struct tls_data *) c->tls;
  long n = MG_IO_WAIT;
  bool was_throttled = c->is_tls_throttled;  // see #3074
  if (!was_throttled) {                      // encrypt new data
    if (len > MG_IO_SIZE) len = MG_IO_SIZE;
    if (len > 16384) len = 16384;
    mg_tls_encrypt(c, (const uint8_t *) buf, len, MG_TLS_APP_DATA);
  }  // else, resend outstanding encrypted data in tls->send
  while (tls->send.len > 0 &&
         (n = mg_io_send(c, tls->send.buf, tls->send.len)) > 0) {
    mg_iobuf_del(&tls->send, 0, (size_t) n);
  }
  c->is_tls_throttled = (tls->send.len > 0 && n == MG_IO_WAIT);
  MG_VERBOSE(("%lu %ld %ld %ld %c %c", c->id, (long) len, (long) tls->send.len,
              n, was_throttled ? 'T' : 't', c->is_tls_throttled ? 'T' : 't'));
  if (n == MG_IO_ERR) return MG_IO_ERR;
  if (was_throttled) return MG_IO_WAIT;  // sent throttled data instead
  return (long) len;  // return len even when throttled, already encripted that
}

long mg_tls_recv(struct mg_connection *c, void *buf, size_t len) {
  int r = 0;
  struct tls_data *tls = (struct tls_data *) c->tls;
  unsigned char *recv_buf;
  size_t minlen;

  r = mg_tls_recv_record(c);
  if (r < 0) {
    return r;
  }
  recv_buf = &c->rtls.buf[tls->recv_offset];

  if (tls->content_type != MG_TLS_APP_DATA) {
    tls->recv_len = 0;
    mg_tls_drop_record(c);
    return MG_IO_WAIT;
  }
  if (buf == NULL || len == 0) return 0L;
  minlen = len < tls->recv_len ? len : tls->recv_len;
  memmove(buf, recv_buf, minlen);
  tls->recv_offset += minlen;
  tls->recv_len -= minlen;
  if (tls->recv_len == 0) {
    mg_tls_drop_record(c);
  }
  return (long) minlen;
}

size_t mg_tls_pending(struct mg_connection *c) {
  struct tls_data *tls = (struct tls_data *) c->tls;
  return tls != NULL ? tls->recv_len : 0;
}

void mg_tls_ctx_init(struct mg_mgr *mgr) {
  (void) mgr;
}

void mg_tls_ctx_free(struct mg_mgr *mgr) {
  (void) mgr;
}
#endif

#ifdef MG_ENABLE_LINES
#line 1 "src/tls_chacha20.c"
#endif
// portable8439 v1.0.1
// Source: https://github.com/DavyLandman/portable8439
// Licensed under CC0-1.0
// Contains poly1305-donna e6ad6e091d30d7f4ec2d4f978be1fcfcbce72781 (Public
// Domain)




#if MG_TLS == MG_TLS_BUILTIN
// ******* BEGIN: chacha-portable/chacha-portable.h ********

#if !defined(__cplusplus) && !defined(_MSC_VER) && \
    (!defined(__STDC_VERSION__) || __STDC_VERSION__ < 199901L)
#error "C99 or newer required"
#endif

#define CHACHA20_KEY_SIZE (32)
#define CHACHA20_NONCE_SIZE (12)

#if defined(_MSC_VER) || defined(__cplusplus)
// add restrict support
#if (defined(_MSC_VER) && _MSC_VER >= 1900) || defined(__clang__) || \
    defined(__GNUC__)
#define restrict __restrict
#else
#define restrict
#endif
#endif

// xor data with a ChaCha20 keystream as per RFC8439
static PORTABLE_8439_DECL void chacha20_xor_stream(
    uint8_t *restrict dest, const uint8_t *restrict source, size_t length,
    const uint8_t key[CHACHA20_KEY_SIZE],
    const uint8_t nonce[CHACHA20_NONCE_SIZE], uint32_t counter);

static PORTABLE_8439_DECL void rfc8439_keygen(
    uint8_t poly_key[32], const uint8_t key[CHACHA20_KEY_SIZE],
    const uint8_t nonce[CHACHA20_NONCE_SIZE]);

// ******* END:   chacha-portable/chacha-portable.h ********
// ******* BEGIN: poly1305-donna/poly1305-donna.h ********

#include <stddef.h>

typedef struct poly1305_context {
  size_t aligner;
  unsigned char opaque[136];
} poly1305_context;

static PORTABLE_8439_DECL void poly1305_init(poly1305_context *ctx,
                                             const unsigned char key[32]);
static PORTABLE_8439_DECL void poly1305_update(poly1305_context *ctx,
                                               const unsigned char *m,
                                               size_t bytes);
static PORTABLE_8439_DECL void poly1305_finish(poly1305_context *ctx,
                                               unsigned char mac[16]);

// ******* END:   poly1305-donna/poly1305-donna.h ********
// ******* BEGIN: chacha-portable.c ********

#include <assert.h>
#include <string.h>

// this is a fresh implementation of chacha20, based on the description in
// rfc8349 it's such a nice compact algorithm that it is easy to do. In
// relationship to other c implementation this implementation:
//  - pure c99
//  - big & little endian support
//  - safe for architectures that don't support unaligned reads
//
// Next to this, we try to be fast as possible without resorting inline
// assembly.

// based on https://sourceforge.net/p/predef/wiki/Endianness/
#if defined(__BYTE_ORDER__) && defined(__ORDER_LITTLE_ENDIAN__) && \
    __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
#define __HAVE_LITTLE_ENDIAN 1
#elif defined(__LITTLE_ENDIAN__) || defined(__ARMEL__) ||                 \
    defined(__THUMBEL__) || defined(__AARCH64EL__) || defined(_MIPSEL) || \
    defined(__MIPSEL) || defined(__MIPSEL__) || defined(__XTENSA_EL__) || \
    defined(__AVR__) || defined(LITTLE_ENDIAN)
#define __HAVE_LITTLE_ENDIAN 1
#endif

#ifndef TEST_SLOW_PATH
#if defined(__HAVE_LITTLE_ENDIAN)
#define FAST_PATH
#endif
#endif

#define CHACHA20_STATE_WORDS (16)
#define CHACHA20_BLOCK_SIZE (CHACHA20_STATE_WORDS * sizeof(uint32_t))

#ifdef FAST_PATH
#define store_32_le(target, source) memcpy(&(target), source, sizeof(uint32_t))
#else
#define store_32_le(target, source)                                 \
  target = (uint32_t) (source)[0] | ((uint32_t) (source)[1]) << 8 | \
           ((uint32_t) (source)[2]) << 16 | ((uint32_t) (source)[3]) << 24
#endif

static void initialize_state(uint32_t state[CHACHA20_STATE_WORDS],
                             const uint8_t key[CHACHA20_KEY_SIZE],
                             const uint8_t nonce[CHACHA20_NONCE_SIZE],
                             uint32_t counter) {
#if 0
#ifdef static_assert
  static_assert(sizeof(uint32_t) == 4,
                "We don't support systems that do not conform to standard of "
                "uint32_t being exact 32bit wide");
#endif
#endif
  state[0] = 0x61707865;
  state[1] = 0x3320646e;
  state[2] = 0x79622d32;
  state[3] = 0x6b206574;
  store_32_le(state[4], key);
  store_32_le(state[5], key + 4);
  store_32_le(state[6], key + 8);
  store_32_le(state[7], key + 12);
  store_32_le(state[8], key + 16);
  store_32_le(state[9], key + 20);
  store_32_le(state[10], key + 24);
  store_32_le(state[11], key + 28);
  state[12] = counter;
  store_32_le(state[13], nonce);
  store_32_le(state[14], nonce + 4);
  store_32_le(state[15], nonce + 8);
}

#define increment_counter(state) (state)[12]++

// source: http://blog.regehr.org/archives/1063
#define rotl32a(x, n) ((x) << (n)) | ((x) >> (32 - (n)))

#define Qround(a, b, c, d) \
  a += b;                  \
  d ^= a;                  \
  d = rotl32a(d, 16);      \
  c += d;                  \
  b ^= c;                  \
  b = rotl32a(b, 12);      \
  a += b;                  \
  d ^= a;                  \
  d = rotl32a(d, 8);       \
  c += d;                  \
  b ^= c;                  \
  b = rotl32a(b, 7);

#define TIMES16(x)                                                          \
  x(0) x(1) x(2) x(3) x(4) x(5) x(6) x(7) x(8) x(9) x(10) x(11) x(12) x(13) \
      x(14) x(15)

static void core_block(const uint32_t *restrict start,
                       uint32_t *restrict output) {
  int i;
// instead of working on the output array,
// we let the compiler allocate 16 local variables on the stack
#define __LV(i) uint32_t __t##i = start[i];
  TIMES16(__LV)

#define __Q(a, b, c, d) Qround(__t##a, __t##b, __t##c, __t##d)

  for (i = 0; i < 10; i++) {
    __Q(0, 4, 8, 12);
    __Q(1, 5, 9, 13);
    __Q(2, 6, 10, 14);
    __Q(3, 7, 11, 15);
    __Q(0, 5, 10, 15);
    __Q(1, 6, 11, 12);
    __Q(2, 7, 8, 13);
    __Q(3, 4, 9, 14);
  }

#define __FIN(i) output[i] = start[i] + __t##i;
  TIMES16(__FIN)
}

#define U8(x) ((uint8_t) ((x) &0xFF))

#ifdef FAST_PATH
#define xor32_le(dst, src, pad)            \
  uint32_t __value;                        \
  memcpy(&__value, src, sizeof(uint32_t)); \
  __value ^= *(pad);                       \
  memcpy(dst, &__value, sizeof(uint32_t));
#else
#define xor32_le(dst, src, pad)           \
  (dst)[0] = (src)[0] ^ U8(*(pad));       \
  (dst)[1] = (src)[1] ^ U8(*(pad) >> 8);  \
  (dst)[2] = (src)[2] ^ U8(*(pad) >> 16); \
  (dst)[3] = (src)[3] ^ U8(*(pad) >> 24);
#endif

#define index8_32(a, ix) ((a) + ((ix) * sizeof(uint32_t)))

#define xor32_blocks(dest, source, pad, words)                    \
  for (i = 0; i < words; i++) {                                   \
    xor32_le(index8_32(dest, i), index8_32(source, i), (pad) + i) \
  }

static void xor_block(uint8_t *restrict dest, const uint8_t *restrict source,
                      const uint32_t *restrict pad, unsigned int chunk_size) {
  unsigned int i, full_blocks = chunk_size / (unsigned int) sizeof(uint32_t);
  // have to be carefull, we are going back from uint32 to uint8, so endianness
  // matters again
  xor32_blocks(dest, source, pad, full_blocks)

      dest += full_blocks * sizeof(uint32_t);
  source += full_blocks * sizeof(uint32_t);
  pad += full_blocks;

  switch (chunk_size % sizeof(uint32_t)) {
    case 1:
      dest[0] = source[0] ^ U8(*pad);
      break;
    case 2:
      dest[0] = source[0] ^ U8(*pad);
      dest[1] = source[1] ^ U8(*pad >> 8);
      break;
    case 3:
      dest[0] = source[0] ^ U8(*pad);
      dest[1] = source[1] ^ U8(*pad >> 8);
      dest[2] = source[2] ^ U8(*pad >> 16);
      break;
  }
}

static void chacha20_xor_stream(uint8_t *restrict dest,
                                const uint8_t *restrict source, size_t length,
                                const uint8_t key[CHACHA20_KEY_SIZE],
                                const uint8_t nonce[CHACHA20_NONCE_SIZE],
                                uint32_t counter) {
  uint32_t state[CHACHA20_STATE_WORDS];
  uint32_t pad[CHACHA20_STATE_WORDS];
  size_t i, b, last_block, full_blocks = length / CHACHA20_BLOCK_SIZE;
  initialize_state(state, key, nonce, counter);
  for (b = 0; b < full_blocks; b++) {
    core_block(state, pad);
    increment_counter(state);
    xor32_blocks(dest, source, pad, CHACHA20_STATE_WORDS) dest +=
        CHACHA20_BLOCK_SIZE;
    source += CHACHA20_BLOCK_SIZE;
  }
  last_block = length % CHACHA20_BLOCK_SIZE;
  if (last_block > 0) {
    core_block(state, pad);
    xor_block(dest, source, pad, (unsigned int) last_block);
  }
}

#ifdef FAST_PATH
#define serialize(poly_key, result) memcpy(poly_key, result, 32)
#else
#define store32_le(target, source)   \
  (target)[0] = U8(*(source));       \
  (target)[1] = U8(*(source) >> 8);  \
  (target)[2] = U8(*(source) >> 16); \
  (target)[3] = U8(*(source) >> 24);

#define serialize(poly_key, result)                 \
  for (i = 0; i < 32 / sizeof(uint32_t); i++) {     \
    store32_le(index8_32(poly_key, i), result + i); \
  }
#endif

static void rfc8439_keygen(uint8_t poly_key[32],
                           const uint8_t key[CHACHA20_KEY_SIZE],
                           const uint8_t nonce[CHACHA20_NONCE_SIZE]) {
  uint32_t state[CHACHA20_STATE_WORDS];
  uint32_t result[CHACHA20_STATE_WORDS];
  size_t i;
  initialize_state(state, key, nonce, 0);
  core_block(state, result);
  serialize(poly_key, result);
  (void) i;
}
// ******* END: chacha-portable.c ********
// ******* BEGIN: poly1305-donna.c ********

/* auto detect between 32bit / 64bit */
#if /* uint128 available on 64bit system*/                              \
    (defined(__SIZEOF_INT128__) &&                                      \
     defined(__LP64__))                       /* MSVC 64bit compiler */ \
    || (defined(_MSC_VER) && defined(_M_X64)) /* gcc >= 4.4 64bit */    \
    || (defined(__GNUC__) && defined(__LP64__) &&                       \
        ((__GNUC__ > 4) || ((__GNUC__ == 4) && (__GNUC_MINOR__ >= 4))))
#define __GUESS64
#else
#define __GUESS32
#endif

#if defined(POLY1305_8BIT)
/*
        poly1305 implementation using 8 bit * 8 bit = 16 bit multiplication and
32 bit addition

        based on the public domain reference version in supercop by djb
static */

#if defined(_MSC_VER) && _MSC_VER < 1700
#define POLY1305_NOINLINE
#elif defined(_MSC_VER)
#define POLY1305_NOINLINE __declspec(noinline)
#elif defined(__GNUC__)
#define POLY1305_NOINLINE __attribute__((noinline))
#else
#define POLY1305_NOINLINE
#endif

#define poly1305_block_size 16

/* 17 + sizeof(size_t) + 51*sizeof(unsigned char) */
typedef struct poly1305_state_internal_t {
  unsigned char buffer[poly1305_block_size];
  size_t leftover;
  unsigned char h[17];
  unsigned char r[17];
  unsigned char pad[17];
  unsigned char final;
} poly1305_state_internal_t;

static void poly1305_init(poly1305_context *ctx, const unsigned char key[32]) {
  poly1305_state_internal_t *st = (poly1305_state_internal_t *) ctx;
  size_t i;

  st->leftover = 0;

  /* h = 0 */
  for (i = 0; i < 17; i++) st->h[i] = 0;

  /* r &= 0xffffffc0ffffffc0ffffffc0fffffff */
  st->r[0] = key[0] & 0xff;
  st->r[1] = key[1] & 0xff;
  st->r[2] = key[2] & 0xff;
  st->r[3] = key[3] & 0x0f;
  st->r[4] = key[4] & 0xfc;
  st->r[5] = key[5] & 0xff;
  st->r[6] = key[6] & 0xff;
  st->r[7] = key[7] & 0x0f;
  st->r[8] = key[8] & 0xfc;
  st->r[9] = key[9] & 0xff;
  st->r[10] = key[10] & 0xff;
  st->r[11] = key[11] & 0x0f;
  st->r[12] = key[12] & 0xfc;
  st->r[13] = key[13] & 0xff;
  st->r[14] = key[14] & 0xff;
  st->r[15] = key[15] & 0x0f;
  st->r[16] = 0;

  /* save pad for later */
  for (i = 0; i < 16; i++) st->pad[i] = key[i + 16];
  st->pad[16] = 0;

  st->final = 0;
}

static void poly1305_add(unsigned char h[17], const unsigned char c[17]) {
  unsigned short u;
  unsigned int i;
  for (u = 0, i = 0; i < 17; i++) {
    u += (unsigned short) h[i] + (unsigned short) c[i];
    h[i] = (unsigned char) u & 0xff;
    u >>= 8;
  }
}

static void poly1305_squeeze(unsigned char h[17], unsigned long hr[17]) {
  unsigned long u;
  unsigned int i;
  u = 0;
  for (i = 0; i < 16; i++) {
    u += hr[i];
    h[i] = (unsigned char) u & 0xff;
    u >>= 8;
  }
  u += hr[16];
  h[16] = (unsigned char) u & 0x03;
  u >>= 2;
  u += (u << 2); /* u *= 5; */
  for (i = 0; i < 16; i++) {
    u += h[i];
    h[i] = (unsigned char) u & 0xff;
    u >>= 8;
  }
  h[16] += (unsigned char) u;
}

static void poly1305_freeze(unsigned char h[17]) {
  const unsigned char minusp[17] = {0x05, 0x00, 0x00, 0x00, 0x00, 0x00,
                                    0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
                                    0x00, 0x00, 0x00, 0x00, 0xfc};
  unsigned char horig[17], negative;
  unsigned int i;

  /* compute h + -p */
  for (i = 0; i < 17; i++) horig[i] = h[i];
  poly1305_add(h, minusp);

  /* select h if h < p, or h + -p if h >= p */
  negative = -(h[16] >> 7);
  for (i = 0; i < 17; i++) h[i] ^= negative & (horig[i] ^ h[i]);
}

static void poly1305_blocks(poly1305_state_internal_t *st,
                            const unsigned char *m, size_t bytes) {
  const unsigned char hibit = st->final ^ 1; /* 1 << 128 */

  while (bytes >= poly1305_block_size) {
    unsigned long hr[17], u;
    unsigned char c[17];
    unsigned int i, j;

    /* h += m */
    for (i = 0; i < 16; i++) c[i] = m[i];
    c[16] = hibit;
    poly1305_add(st->h, c);

    /* h *= r */
    for (i = 0; i < 17; i++) {
      u = 0;
      for (j = 0; j <= i; j++) {
        u += (unsigned short) st->h[j] * st->r[i - j];
      }
      for (j = i + 1; j < 17; j++) {
        unsigned long v = (unsigned short) st->h[j] * st->r[i + 17 - j];
        v = ((v << 8) + (v << 6)); /* v *= (5 << 6); */
        u += v;
      }
      hr[i] = u;
    }

    /* (partial) h %= p */
    poly1305_squeeze(st->h, hr);

    m += poly1305_block_size;
    bytes -= poly1305_block_size;
  }
}

static POLY1305_NOINLINE void poly1305_finish(poly1305_context *ctx,
                                              unsigned char mac[16]) {
  poly1305_state_internal_t *st = (poly1305_state_internal_t *) ctx;
  size_t i;

  /* process the remaining block */
  if (st->leftover) {
    size_t i = st->leftover;
    st->buffer[i++] = 1;
    for (; i < poly1305_block_size; i++) st->buffer[i] = 0;
    st->final = 1;
    poly1305_blocks(st, st->buffer, poly1305_block_size);
  }

  /* fully reduce h */
  poly1305_freeze(st->h);

  /* h = (h + pad) % (1 << 128) */
  poly1305_add(st->h, st->pad);
  for (i = 0; i < 16; i++) mac[i] = st->h[i];

  /* zero out the state */
  for (i = 0; i < 17; i++) st->h[i] = 0;
  for (i = 0; i < 17; i++) st->r[i] = 0;
  for (i = 0; i < 17; i++) st->pad[i] = 0;
}
#elif defined(POLY1305_16BIT)
/*
        poly1305 implementation using 16 bit * 16 bit = 32 bit multiplication
and 32 bit addition static */

#if defined(_MSC_VER) && _MSC_VER < 1700
#define POLY1305_NOINLINE
#elif defined(_MSC_VER)
#define POLY1305_NOINLINE __declspec(noinline)
#elif defined(__GNUC__)
#define POLY1305_NOINLINE __attribute__((noinline))
#else
#define POLY1305_NOINLINE
#endif

#define poly1305_block_size 16

/* 17 + sizeof(size_t) + 18*sizeof(unsigned short) */
typedef struct poly1305_state_internal_t {
  unsigned char buffer[poly1305_block_size];
  size_t leftover;
  unsigned short r[10];
  unsigned short h[10];
  unsigned short pad[8];
  unsigned char final;
} poly1305_state_internal_t;

/* interpret two 8 bit unsigned integers as a 16 bit unsigned integer in little
 * endian */
static unsigned short U8TO16(const unsigned char *p) {
  return (((unsigned short) (p[0] & 0xff)) |
          ((unsigned short) (p[1] & 0xff) << 8));
}

/* store a 16 bit unsigned integer as two 8 bit unsigned integers in little
 * endian */
static void U16TO8(unsigned char *p, unsigned short v) {
  p[0] = (v) &0xff;
  p[1] = (v >> 8) & 0xff;
}

static void poly1305_init(poly1305_context *ctx, const unsigned char key[32]) {
  poly1305_state_internal_t *st = (poly1305_state_internal_t *) ctx;
  unsigned short t0, t1, t2, t3, t4, t5, t6, t7;
  size_t i;

  /* r &= 0xffffffc0ffffffc0ffffffc0fffffff */
  t0 = U8TO16(&key[0]);
  st->r[0] = (t0) &0x1fff;
  t1 = U8TO16(&key[2]);
  st->r[1] = ((t0 >> 13) | (t1 << 3)) & 0x1fff;
  t2 = U8TO16(&key[4]);
  st->r[2] = ((t1 >> 10) | (t2 << 6)) & 0x1f03;
  t3 = U8TO16(&key[6]);
  st->r[3] = ((t2 >> 7) | (t3 << 9)) & 0x1fff;
  t4 = U8TO16(&key[8]);
  st->r[4] = ((t3 >> 4) | (t4 << 12)) & 0x00ff;
  st->r[5] = ((t4 >> 1)) & 0x1ffe;
  t5 = U8TO16(&key[10]);
  st->r[6] = ((t4 >> 14) | (t5 << 2)) & 0x1fff;
  t6 = U8TO16(&key[12]);
  st->r[7] = ((t5 >> 11) | (t6 << 5)) & 0x1f81;
  t7 = U8TO16(&key[14]);
  st->r[8] = ((t6 >> 8) | (t7 << 8)) & 0x1fff;
  st->r[9] = ((t7 >> 5)) & 0x007f;

  /* h = 0 */
  for (i = 0; i < 10; i++) st->h[i] = 0;

  /* save pad for later */
  for (i = 0; i < 8; i++) st->pad[i] = U8TO16(&key[16 + (2 * i)]);

  st->leftover = 0;
  st->final = 0;
}

static void poly1305_blocks(poly1305_state_internal_t *st,
                            const unsigned char *m, size_t bytes) {
  const unsigned short hibit = (st->final) ? 0 : (1 << 11); /* 1 << 128 */
  unsigned short t0, t1, t2, t3, t4, t5, t6, t7;
  unsigned long d[10];
  unsigned long c;

  while (bytes >= poly1305_block_size) {
    size_t i, j;

    /* h += m[i] */
    t0 = U8TO16(&m[0]);
    st->h[0] += (t0) &0x1fff;
    t1 = U8TO16(&m[2]);
    st->h[1] += ((t0 >> 13) | (t1 << 3)) & 0x1fff;
    t2 = U8TO16(&m[4]);
    st->h[2] += ((t1 >> 10) | (t2 << 6)) & 0x1fff;
    t3 = U8TO16(&m[6]);
    st->h[3] += ((t2 >> 7) | (t3 << 9)) & 0x1fff;
    t4 = U8TO16(&m[8]);
    st->h[4] += ((t3 >> 4) | (t4 << 12)) & 0x1fff;
    st->h[5] += ((t4 >> 1)) & 0x1fff;
    t5 = U8TO16(&m[10]);
    st->h[6] += ((t4 >> 14) | (t5 << 2)) & 0x1fff;
    t6 = U8TO16(&m[12]);
    st->h[7] += ((t5 >> 11) | (t6 << 5)) & 0x1fff;
    t7 = U8TO16(&m[14]);
    st->h[8] += ((t6 >> 8) | (t7 << 8)) & 0x1fff;
    st->h[9] += ((t7 >> 5)) | hibit;

    /* h *= r, (partial) h %= p */
    for (i = 0, c = 0; i < 10; i++) {
      d[i] = c;
      for (j = 0; j < 10; j++) {
        d[i] += (unsigned long) st->h[j] *
                ((j <= i) ? st->r[i - j] : (5 * st->r[i + 10 - j]));
        /* Sum(h[i] * r[i] * 5) will overflow slightly above 6 products with an
         * unclamped r, so carry at 5 */
        if (j == 4) {
          c = (d[i] >> 13);
          d[i] &= 0x1fff;
        }
      }
      c += (d[i] >> 13);
      d[i] &= 0x1fff;
    }
    c = ((c << 2) + c); /* c *= 5 */
    c += d[0];
    d[0] = ((unsigned short) c & 0x1fff);
    c = (c >> 13);
    d[1] += c;

    for (i = 0; i < 10; i++) st->h[i] = (unsigned short) d[i];

    m += poly1305_block_size;
    bytes -= poly1305_block_size;
  }
}

static POLY1305_NOINLINE void poly1305_finish(poly1305_context *ctx,
                                              unsigned char mac[16]) {
  poly1305_state_internal_t *st = (poly1305_state_internal_t *) ctx;
  unsigned short c;
  unsigned short g[10];
  unsigned short mask;
  unsigned long f;
  size_t i;

  /* process the remaining block */
  if (st->leftover) {
    size_t i = st->leftover;
    st->buffer[i++] = 1;
    for (; i < poly1305_block_size; i++) st->buffer[i] = 0;
    st->final = 1;
    poly1305_blocks(st, st->buffer, poly1305_block_size);
  }

  /* fully carry h */
  c = st->h[1] >> 13;
  st->h[1] &= 0x1fff;
  for (i = 2; i < 10; i++) {
    st->h[i] += c;
    c = st->h[i] >> 13;
    st->h[i] &= 0x1fff;
  }
  st->h[0] += (c * 5);
  c = st->h[0] >> 13;
  st->h[0] &= 0x1fff;
  st->h[1] += c;
  c = st->h[1] >> 13;
  st->h[1] &= 0x1fff;
  st->h[2] += c;

  /* compute h + -p */
  g[0] = st->h[0] + 5;
  c = g[0] >> 13;
  g[0] &= 0x1fff;
  for (i = 1; i < 10; i++) {
    g[i] = st->h[i] + c;
    c = g[i] >> 13;
    g[i] &= 0x1fff;
  }

  /* select h if h < p, or h + -p if h >= p */
  mask = (c ^ 1) - 1;
  for (i = 0; i < 10; i++) g[i] &= mask;
  mask = ~mask;
  for (i = 0; i < 10; i++) st->h[i] = (st->h[i] & mask) | g[i];

  /* h = h % (2^128) */
  st->h[0] = ((st->h[0]) | (st->h[1] << 13)) & 0xffff;
  st->h[1] = ((st->h[1] >> 3) | (st->h[2] << 10)) & 0xffff;
  st->h[2] = ((st->h[2] >> 6) | (st->h[3] << 7)) & 0xffff;
  st->h[3] = ((st->h[3] >> 9) | (st->h[4] << 4)) & 0xffff;
  st->h[4] = ((st->h[4] >> 12) | (st->h[5] << 1) | (st->h[6] << 14)) & 0xffff;
  st->h[5] = ((st->h[6] >> 2) | (st->h[7] << 11)) & 0xffff;
  st->h[6] = ((st->h[7] >> 5) | (st->h[8] << 8)) & 0xffff;
  st->h[7] = ((st->h[8] >> 8) | (st->h[9] << 5)) & 0xffff;

  /* mac = (h + pad) % (2^128) */
  f = (unsigned long) st->h[0] + st->pad[0];
  st->h[0] = (unsigned short) f;
  for (i = 1; i < 8; i++) {
    f = (unsigned long) st->h[i] + st->pad[i] + (f >> 16);
    st->h[i] = (unsigned short) f;
  }

  for (i = 0; i < 8; i++) U16TO8(mac + (i * 2), st->h[i]);

  /* zero out the state */
  for (i = 0; i < 10; i++) st->h[i] = 0;
  for (i = 0; i < 10; i++) st->r[i] = 0;
  for (i = 0; i < 8; i++) st->pad[i] = 0;
}
#elif defined(POLY1305_32BIT) || \
    (!defined(POLY1305_64BIT) && defined(__GUESS32))
/*
        poly1305 implementation using 32 bit * 32 bit = 64 bit multiplication
and 64 bit addition static */

#if defined(_MSC_VER) && _MSC_VER < 1700
#define POLY1305_NOINLINE
#elif defined(_MSC_VER)
#define POLY1305_NOINLINE __declspec(noinline)
#elif defined(__GNUC__)
#define POLY1305_NOINLINE __attribute__((noinline))
#else
#define POLY1305_NOINLINE
#endif

#define poly1305_block_size 16

/* 17 + sizeof(size_t) + 14*sizeof(unsigned long) */
typedef struct poly1305_state_internal_t {
  unsigned long r[5];
  unsigned long h[5];
  unsigned long pad[4];
  size_t leftover;
  unsigned char buffer[poly1305_block_size];
  unsigned char final;
} poly1305_state_internal_t;

/* interpret four 8 bit unsigned integers as a 32 bit unsigned integer in little
 * endian */
static unsigned long U8TO32(const unsigned char *p) {
  return (((unsigned long) (p[0] & 0xff)) |
          ((unsigned long) (p[1] & 0xff) << 8) |
          ((unsigned long) (p[2] & 0xff) << 16) |
          ((unsigned long) (p[3] & 0xff) << 24));
}

/* store a 32 bit unsigned integer as four 8 bit unsigned integers in little
 * endian */
static void U32TO8(unsigned char *p, unsigned long v) {
  p[0] = (unsigned char) ((v) &0xff);
  p[1] = (unsigned char) ((v >> 8) & 0xff);
  p[2] = (unsigned char) ((v >> 16) & 0xff);
  p[3] = (unsigned char) ((v >> 24) & 0xff);
}

static void poly1305_init(poly1305_context *ctx, const unsigned char key[32]) {
  poly1305_state_internal_t *st = (poly1305_state_internal_t *) ctx;

  /* r &= 0xffffffc0ffffffc0ffffffc0fffffff */
  st->r[0] = (U8TO32(&key[0])) & 0x3ffffff;
  st->r[1] = (U8TO32(&key[3]) >> 2) & 0x3ffff03;
  st->r[2] = (U8TO32(&key[6]) >> 4) & 0x3ffc0ff;
  st->r[3] = (U8TO32(&key[9]) >> 6) & 0x3f03fff;
  st->r[4] = (U8TO32(&key[12]) >> 8) & 0x00fffff;

  /* h = 0 */
  st->h[0] = 0;
  st->h[1] = 0;
  st->h[2] = 0;
  st->h[3] = 0;
  st->h[4] = 0;

  /* save pad for later */
  st->pad[0] = U8TO32(&key[16]);
  st->pad[1] = U8TO32(&key[20]);
  st->pad[2] = U8TO32(&key[24]);
  st->pad[3] = U8TO32(&key[28]);

  st->leftover = 0;
  st->final = 0;
}

static void poly1305_blocks(poly1305_state_internal_t *st,
                            const unsigned char *m, size_t bytes) {
  const unsigned long hibit = (st->final) ? 0 : (1UL << 24); /* 1 << 128 */
  unsigned long r0, r1, r2, r3, r4;
  unsigned long s1, s2, s3, s4;
  unsigned long h0, h1, h2, h3, h4;
  uint64_t d0, d1, d2, d3, d4;
  unsigned long c;

  r0 = st->r[0];
  r1 = st->r[1];
  r2 = st->r[2];
  r3 = st->r[3];
  r4 = st->r[4];

  s1 = r1 * 5;
  s2 = r2 * 5;
  s3 = r3 * 5;
  s4 = r4 * 5;

  h0 = st->h[0];
  h1 = st->h[1];
  h2 = st->h[2];
  h3 = st->h[3];
  h4 = st->h[4];

  while (bytes >= poly1305_block_size) {
    /* h += m[i] */
    h0 += (U8TO32(m + 0)) & 0x3ffffff;
    h1 += (U8TO32(m + 3) >> 2) & 0x3ffffff;
    h2 += (U8TO32(m + 6) >> 4) & 0x3ffffff;
    h3 += (U8TO32(m + 9) >> 6) & 0x3ffffff;
    h4 += (U8TO32(m + 12) >> 8) | hibit;

    /* h *= r */
    d0 = ((uint64_t) h0 * r0) + ((uint64_t) h1 * s4) + ((uint64_t) h2 * s3) +
         ((uint64_t) h3 * s2) + ((uint64_t) h4 * s1);
    d1 = ((uint64_t) h0 * r1) + ((uint64_t) h1 * r0) + ((uint64_t) h2 * s4) +
         ((uint64_t) h3 * s3) + ((uint64_t) h4 * s2);
    d2 = ((uint64_t) h0 * r2) + ((uint64_t) h1 * r1) + ((uint64_t) h2 * r0) +
         ((uint64_t) h3 * s4) + ((uint64_t) h4 * s3);
    d3 = ((uint64_t) h0 * r3) + ((uint64_t) h1 * r2) + ((uint64_t) h2 * r1) +
         ((uint64_t) h3 * r0) + ((uint64_t) h4 * s4);
    d4 = ((uint64_t) h0 * r4) + ((uint64_t) h1 * r3) + ((uint64_t) h2 * r2) +
         ((uint64_t) h3 * r1) + ((uint64_t) h4 * r0);

    /* (partial) h %= p */
    c = (unsigned long) (d0 >> 26);
    h0 = (unsigned long) d0 & 0x3ffffff;
    d1 += c;
    c = (unsigned long) (d1 >> 26);
    h1 = (unsigned long) d1 & 0x3ffffff;
    d2 += c;
    c = (unsigned long) (d2 >> 26);
    h2 = (unsigned long) d2 & 0x3ffffff;
    d3 += c;
    c = (unsigned long) (d3 >> 26);
    h3 = (unsigned long) d3 & 0x3ffffff;
    d4 += c;
    c = (unsigned long) (d4 >> 26);
    h4 = (unsigned long) d4 & 0x3ffffff;
    h0 += c * 5;
    c = (h0 >> 26);
    h0 = h0 & 0x3ffffff;
    h1 += c;

    m += poly1305_block_size;
    bytes -= poly1305_block_size;
  }

  st->h[0] = h0;
  st->h[1] = h1;
  st->h[2] = h2;
  st->h[3] = h3;
  st->h[4] = h4;
}

static POLY1305_NOINLINE void poly1305_finish(poly1305_context *ctx,
                                              unsigned char mac[16]) {
  poly1305_state_internal_t *st = (poly1305_state_internal_t *) ctx;
  unsigned long h0, h1, h2, h3, h4, c;
  unsigned long g0, g1, g2, g3, g4;
  uint64_t f;
  unsigned long mask;

  /* process the remaining block */
  if (st->leftover) {
    size_t i = st->leftover;
    st->buffer[i++] = 1;
    for (; i < poly1305_block_size; i++) st->buffer[i] = 0;
    st->final = 1;
    poly1305_blocks(st, st->buffer, poly1305_block_size);
  }

  /* fully carry h */
  h0 = st->h[0];
  h1 = st->h[1];
  h2 = st->h[2];
  h3 = st->h[3];
  h4 = st->h[4];

  c = h1 >> 26;
  h1 = h1 & 0x3ffffff;
  h2 += c;
  c = h2 >> 26;
  h2 = h2 & 0x3ffffff;
  h3 += c;
  c = h3 >> 26;
  h3 = h3 & 0x3ffffff;
  h4 += c;
  c = h4 >> 26;
  h4 = h4 & 0x3ffffff;
  h0 += c * 5;
  c = h0 >> 26;
  h0 = h0 & 0x3ffffff;
  h1 += c;

  /* compute h + -p */
  g0 = h0 + 5;
  c = g0 >> 26;
  g0 &= 0x3ffffff;
  g1 = h1 + c;
  c = g1 >> 26;
  g1 &= 0x3ffffff;
  g2 = h2 + c;
  c = g2 >> 26;
  g2 &= 0x3ffffff;
  g3 = h3 + c;
  c = g3 >> 26;
  g3 &= 0x3ffffff;
  g4 = h4 + c - (1UL << 26);

  /* select h if h < p, or h + -p if h >= p */
  mask = (g4 >> ((sizeof(unsigned long) * 8) - 1)) - 1;
  g0 &= mask;
  g1 &= mask;
  g2 &= mask;
  g3 &= mask;
  g4 &= mask;
  mask = ~mask;
  h0 = (h0 & mask) | g0;
  h1 = (h1 & mask) | g1;
  h2 = (h2 & mask) | g2;
  h3 = (h3 & mask) | g3;
  h4 = (h4 & mask) | g4;

  /* h = h % (2^128) */
  h0 = ((h0) | (h1 << 26)) & 0xffffffff;
  h1 = ((h1 >> 6) | (h2 << 20)) & 0xffffffff;
  h2 = ((h2 >> 12) | (h3 << 14)) & 0xffffffff;
  h3 = ((h3 >> 18) | (h4 << 8)) & 0xffffffff;

  /* mac = (h + pad) % (2^128) */
  f = (uint64_t) h0 + st->pad[0];
  h0 = (unsigned long) f;
  f = (uint64_t) h1 + st->pad[1] + (f >> 32);
  h1 = (unsigned long) f;
  f = (uint64_t) h2 + st->pad[2] + (f >> 32);
  h2 = (unsigned long) f;
  f = (uint64_t) h3 + st->pad[3] + (f >> 32);
  h3 = (unsigned long) f;

  U32TO8(mac + 0, h0);
  U32TO8(mac + 4, h1);
  U32TO8(mac + 8, h2);
  U32TO8(mac + 12, h3);

  /* zero out the state */
  st->h[0] = 0;
  st->h[1] = 0;
  st->h[2] = 0;
  st->h[3] = 0;
  st->h[4] = 0;
  st->r[0] = 0;
  st->r[1] = 0;
  st->r[2] = 0;
  st->r[3] = 0;
  st->r[4] = 0;
  st->pad[0] = 0;
  st->pad[1] = 0;
  st->pad[2] = 0;
  st->pad[3] = 0;
}

#else
/*
        poly1305 implementation using 64 bit * 64 bit = 128 bit multiplication
and 128 bit addition static */

#if defined(_MSC_VER)

typedef struct uint128_t {
  uint64_t lo;
  uint64_t hi;
} uint128_t;

#define MUL128(out, x, y) out.lo = _umul128((x), (y), &out.hi)
#define ADD(out, in)                \
  {                                 \
    uint64_t t = out.lo;            \
    out.lo += in.lo;                \
    out.hi += (out.lo < t) + in.hi; \
  }
#define ADDLO(out, in)      \
  {                         \
    uint64_t t = out.lo;    \
    out.lo += in;           \
    out.hi += (out.lo < t); \
  }
#define SHR(in, shift) (__shiftright128(in.lo, in.hi, (shift)))
#define LO(in) (in.lo)

#if defined(_MSC_VER) && _MSC_VER < 1700
#define POLY1305_NOINLINE
#else
#define POLY1305_NOINLINE __declspec(noinline)
#endif
#elif defined(__GNUC__)
#if defined(__SIZEOF_INT128__)
// Get rid of GCC warning "ISO C does not support '__int128' types"
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wpedantic"
typedef unsigned __int128 uint128_t;
#pragma GCC diagnostic pop
#else
typedef unsigned uint128_t __attribute__((mode(TI)));
#endif

#define MUL128(out, x, y) out = ((uint128_t) x * y)
#define ADD(out, in) out += in
#define ADDLO(out, in) out += in
#define SHR(in, shift) (uint64_t)(in >> (shift))
#define LO(in) (uint64_t)(in)

#define POLY1305_NOINLINE __attribute__((noinline))
#endif

#define poly1305_block_size 16

/* 17 + sizeof(size_t) + 8*sizeof(uint64_t) */
typedef struct poly1305_state_internal_t {
  uint64_t r[3];
  uint64_t h[3];
  uint64_t pad[2];
  size_t leftover;
  unsigned char buffer[poly1305_block_size];
  unsigned char final;
} poly1305_state_internal_t;

/* interpret eight 8 bit unsigned integers as a 64 bit unsigned integer in
 * little endian */
static uint64_t U8TO64(const unsigned char *p) {
  return (((uint64_t) (p[0] & 0xff)) | ((uint64_t) (p[1] & 0xff) << 8) |
          ((uint64_t) (p[2] & 0xff) << 16) | ((uint64_t) (p[3] & 0xff) << 24) |
          ((uint64_t) (p[4] & 0xff) << 32) | ((uint64_t) (p[5] & 0xff) << 40) |
          ((uint64_t) (p[6] & 0xff) << 48) | ((uint64_t) (p[7] & 0xff) << 56));
}

/* store a 64 bit unsigned integer as eight 8 bit unsigned integers in little
 * endian */
static void U64TO8(unsigned char *p, uint64_t v) {
  p[0] = (unsigned char) ((v) &0xff);
  p[1] = (unsigned char) ((v >> 8) & 0xff);
  p[2] = (unsigned char) ((v >> 16) & 0xff);
  p[3] = (unsigned char) ((v >> 24) & 0xff);
  p[4] = (unsigned char) ((v >> 32) & 0xff);
  p[5] = (unsigned char) ((v >> 40) & 0xff);
  p[6] = (unsigned char) ((v >> 48) & 0xff);
  p[7] = (unsigned char) ((v >> 56) & 0xff);
}

static void poly1305_init(poly1305_context *ctx, const unsigned char key[32]) {
  poly1305_state_internal_t *st = (poly1305_state_internal_t *) ctx;
  uint64_t t0, t1;

  /* r &= 0xffffffc0ffffffc0ffffffc0fffffff */
  t0 = U8TO64(&key[0]);
  t1 = U8TO64(&key[8]);

  st->r[0] = (t0) &0xffc0fffffff;
  st->r[1] = ((t0 >> 44) | (t1 << 20)) & 0xfffffc0ffff;
  st->r[2] = ((t1 >> 24)) & 0x00ffffffc0f;

  /* h = 0 */
  st->h[0] = 0;
  st->h[1] = 0;
  st->h[2] = 0;

  /* save pad for later */
  st->pad[0] = U8TO64(&key[16]);
  st->pad[1] = U8TO64(&key[24]);

  st->leftover = 0;
  st->final = 0;
}

static void poly1305_blocks(poly1305_state_internal_t *st,
                            const unsigned char *m, size_t bytes) {
  const uint64_t hibit = (st->final) ? 0 : ((uint64_t) 1 << 40); /* 1 << 128 */
  uint64_t r0, r1, r2;
  uint64_t s1, s2;
  uint64_t h0, h1, h2;
  uint64_t c;
  uint128_t d0, d1, d2, d;

  r0 = st->r[0];
  r1 = st->r[1];
  r2 = st->r[2];

  h0 = st->h[0];
  h1 = st->h[1];
  h2 = st->h[2];

  s1 = r1 * (5 << 2);
  s2 = r2 * (5 << 2);

  while (bytes >= poly1305_block_size) {
    uint64_t t0, t1;

    /* h += m[i] */
    t0 = U8TO64(&m[0]);
    t1 = U8TO64(&m[8]);

    h0 += ((t0) &0xfffffffffff);
    h1 += (((t0 >> 44) | (t1 << 20)) & 0xfffffffffff);
    h2 += (((t1 >> 24)) & 0x3ffffffffff) | hibit;

    /* h *= r */
    MUL128(d0, h0, r0);
    MUL128(d, h1, s2);
    ADD(d0, d);
    MUL128(d, h2, s1);
    ADD(d0, d);
    MUL128(d1, h0, r1);
    MUL128(d, h1, r0);
    ADD(d1, d);
    MUL128(d, h2, s2);
    ADD(d1, d);
    MUL128(d2, h0, r2);
    MUL128(d, h1, r1);
    ADD(d2, d);
    MUL128(d, h2, r0);
    ADD(d2, d);

    /* (partial) h %= p */
    c = SHR(d0, 44);
    h0 = LO(d0) & 0xfffffffffff;
    ADDLO(d1, c);
    c = SHR(d1, 44);
    h1 = LO(d1) & 0xfffffffffff;
    ADDLO(d2, c);
    c = SHR(d2, 42);
    h2 = LO(d2) & 0x3ffffffffff;
    h0 += c * 5;
    c = (h0 >> 44);
    h0 = h0 & 0xfffffffffff;
    h1 += c;

    m += poly1305_block_size;
    bytes -= poly1305_block_size;
  }

  st->h[0] = h0;
  st->h[1] = h1;
  st->h[2] = h2;
}

static POLY1305_NOINLINE void poly1305_finish(poly1305_context *ctx,
                                              unsigned char mac[16]) {
  poly1305_state_internal_t *st = (poly1305_state_internal_t *) ctx;
  uint64_t h0, h1, h2, c;
  uint64_t g0, g1, g2;
  uint64_t t0, t1;

  /* process the remaining block */
  if (st->leftover) {
    size_t i = st->leftover;
    st->buffer[i] = 1;
    for (i = i + 1; i < poly1305_block_size; i++) st->buffer[i] = 0;
    st->final = 1;
    poly1305_blocks(st, st->buffer, poly1305_block_size);
  }

  /* fully carry h */
  h0 = st->h[0];
  h1 = st->h[1];
  h2 = st->h[2];

  c = (h1 >> 44);
  h1 &= 0xfffffffffff;
  h2 += c;
  c = (h2 >> 42);
  h2 &= 0x3ffffffffff;
  h0 += c * 5;
  c = (h0 >> 44);
  h0 &= 0xfffffffffff;
  h1 += c;
  c = (h1 >> 44);
  h1 &= 0xfffffffffff;
  h2 += c;
  c = (h2 >> 42);
  h2 &= 0x3ffffffffff;
  h0 += c * 5;
  c = (h0 >> 44);
  h0 &= 0xfffffffffff;
  h1 += c;

  /* compute h + -p */
  g0 = h0 + 5;
  c = (g0 >> 44);
  g0 &= 0xfffffffffff;
  g1 = h1 + c;
  c = (g1 >> 44);
  g1 &= 0xfffffffffff;
  g2 = h2 + c - ((uint64_t) 1 << 42);

  /* select h if h < p, or h + -p if h >= p */
  c = (g2 >> ((sizeof(uint64_t) * 8) - 1)) - 1;
  g0 &= c;
  g1 &= c;
  g2 &= c;
  c = ~c;
  h0 = (h0 & c) | g0;
  h1 = (h1 & c) | g1;
  h2 = (h2 & c) | g2;

  /* h = (h + pad) */
  t0 = st->pad[0];
  t1 = st->pad[1];

  h0 += ((t0) &0xfffffffffff);
  c = (h0 >> 44);
  h0 &= 0xfffffffffff;
  h1 += (((t0 >> 44) | (t1 << 20)) & 0xfffffffffff) + c;
  c = (h1 >> 44);
  h1 &= 0xfffffffffff;
  h2 += (((t1 >> 24)) & 0x3ffffffffff) + c;
  h2 &= 0x3ffffffffff;

  /* mac = h % (2^128) */
  h0 = ((h0) | (h1 << 44));
  h1 = ((h1 >> 20) | (h2 << 24));

  U64TO8(&mac[0], h0);
  U64TO8(&mac[8], h1);

  /* zero out the state */
  st->h[0] = 0;
  st->h[1] = 0;
  st->h[2] = 0;
  st->r[0] = 0;
  st->r[1] = 0;
  st->r[2] = 0;
  st->pad[0] = 0;
  st->pad[1] = 0;
}

#endif

static void poly1305_update(poly1305_context *ctx, const unsigned char *m,
                            size_t bytes) {
  poly1305_state_internal_t *st = (poly1305_state_internal_t *) ctx;
  size_t i;

  /* handle leftover */
  if (st->leftover) {
    size_t want = (poly1305_block_size - st->leftover);
    if (want > bytes) want = bytes;
    for (i = 0; i < want; i++) st->buffer[st->leftover + i] = m[i];
    bytes -= want;
    m += want;
    st->leftover += want;
    if (st->leftover < poly1305_block_size) return;
    poly1305_blocks(st, st->buffer, poly1305_block_size);
    st->leftover = 0;
  }

  /* process full blocks */
  if (bytes >= poly1305_block_size) {
    size_t want = (bytes & (size_t) ~(poly1305_block_size - 1));
    poly1305_blocks(st, m, want);
    m += want;
    bytes -= want;
  }

  /* store leftover */
  if (bytes) {
    for (i = 0; i < bytes; i++) st->buffer[st->leftover + i] = m[i];
    st->leftover += bytes;
  }
}

// ******* END: poly1305-donna.c ********
// ******* BEGIN: portable8439.c ********

#define __CHACHA20_BLOCK_SIZE (64)
#define __POLY1305_KEY_SIZE (32)

static PORTABLE_8439_DECL uint8_t __ZEROES[16] = {0};
static PORTABLE_8439_DECL void pad_if_needed(poly1305_context *ctx,
                                             size_t size) {
  size_t padding = size % 16;
  if (padding != 0) {
    poly1305_update(ctx, __ZEROES, 16 - padding);
  }
}

#define __u8(v) ((uint8_t) ((v) &0xFF))

// TODO: make this depending on the unaligned/native read size possible
static PORTABLE_8439_DECL void write_64bit_int(poly1305_context *ctx,
                                               uint64_t value) {
  uint8_t result[8];
  result[0] = __u8(value);
  result[1] = __u8(value >> 8);
  result[2] = __u8(value >> 16);
  result[3] = __u8(value >> 24);
  result[4] = __u8(value >> 32);
  result[5] = __u8(value >> 40);
  result[6] = __u8(value >> 48);
  result[7] = __u8(value >> 56);
  poly1305_update(ctx, result, 8);
}

static PORTABLE_8439_DECL void poly1305_calculate_mac(
    uint8_t *mac, const uint8_t *cipher_text, size_t cipher_text_size,
    const uint8_t key[RFC_8439_KEY_SIZE],
    const uint8_t nonce[RFC_8439_NONCE_SIZE], const uint8_t *ad,
    size_t ad_size) {
  // init poly key (section 2.6)
  uint8_t poly_key[__POLY1305_KEY_SIZE] = {0};
  poly1305_context poly_ctx;
  rfc8439_keygen(poly_key, key, nonce);
  // start poly1305 mac
  poly1305_init(&poly_ctx, poly_key);

  if (ad != NULL && ad_size > 0) {
    // write AD if present
    poly1305_update(&poly_ctx, ad, ad_size);
    pad_if_needed(&poly_ctx, ad_size);
  }

  // now write the cipher text
  poly1305_update(&poly_ctx, cipher_text, cipher_text_size);
  pad_if_needed(&poly_ctx, cipher_text_size);

  // write sizes
  write_64bit_int(&poly_ctx, ad_size);
  write_64bit_int(&poly_ctx, cipher_text_size);

  // calculate MAC
  poly1305_finish(&poly_ctx, mac);
}

#define MG_PM(p) ((size_t) (p))

// pointers overlap if the smaller either ahead of the end,
// or its end is before the start of the other
//
// s_size should be smaller or equal to b_size
#define MG_OVERLAPPING(s, s_size, b, b_size) \
  (MG_PM(s) < MG_PM((b) + (b_size))) && (MG_PM(b) < MG_PM((s) + (s_size)))

PORTABLE_8439_DECL size_t mg_chacha20_poly1305_encrypt(
    uint8_t *restrict cipher_text, const uint8_t key[RFC_8439_KEY_SIZE],
    const uint8_t nonce[RFC_8439_NONCE_SIZE], const uint8_t *restrict ad,
    size_t ad_size, const uint8_t *restrict plain_text,
    size_t plain_text_size) {
  size_t new_size = plain_text_size + RFC_8439_TAG_SIZE;
  if (MG_OVERLAPPING(plain_text, plain_text_size, cipher_text, new_size)) {
    return (size_t) -1;
  }
  chacha20_xor_stream(cipher_text, plain_text, plain_text_size, key, nonce, 1);
  poly1305_calculate_mac(cipher_text + plain_text_size, cipher_text,
                         plain_text_size, key, nonce, ad, ad_size);
  return new_size;
}

PORTABLE_8439_DECL size_t mg_chacha20_poly1305_decrypt(
    uint8_t *restrict plain_text, const uint8_t key[RFC_8439_KEY_SIZE],
    const uint8_t nonce[RFC_8439_NONCE_SIZE],
    const uint8_t *restrict cipher_text, size_t cipher_text_size) {
  // first we calculate the mac and see if it lines up, only then do we decrypt
  size_t actual_size = cipher_text_size - RFC_8439_TAG_SIZE;
  if (MG_OVERLAPPING(plain_text, actual_size, cipher_text, cipher_text_size)) {
    return (size_t) -1;
  }

  chacha20_xor_stream(plain_text, cipher_text, actual_size, key, nonce, 1);
  return actual_size;
}
// ******* END:   portable8439.c ********
#endif  // MG_TLS == MG_TLS_BUILTIN

#ifdef MG_ENABLE_LINES
#line 1 "src/tls_dummy.c"
#endif


#if MG_TLS == MG_TLS_NONE
void mg_tls_init(struct mg_connection *c, const struct mg_tls_opts *opts) {
  (void) opts;
  mg_error(c, "TLS is not enabled");
}
void mg_tls_handshake(struct mg_connection *c) {
  (void) c;
}
void mg_tls_free(struct mg_connection *c) {
  (void) c;
}
long mg_tls_recv(struct mg_connection *c, void *buf, size_t len) {
  return c == NULL || buf == NULL || len == 0 ? 0 : -1;
}
long mg_tls_send(struct mg_connection *c, const void *buf, size_t len) {
  return c == NULL || buf == NULL || len == 0 ? 0 : -1;
}
size_t mg_tls_pending(struct mg_connection *c) {
  (void) c;
  return 0;
}
void mg_tls_ctx_init(struct mg_mgr *mgr) {
  (void) mgr;
}
void mg_tls_ctx_free(struct mg_mgr *mgr) {
  (void) mgr;
}
#endif

#ifdef MG_ENABLE_LINES
#line 1 "src/tls_mbed.c"
#endif



#if MG_TLS == MG_TLS_MBED

#if defined(MBEDTLS_VERSION_NUMBER) && MBEDTLS_VERSION_NUMBER >= 0x03000000
#define MG_MBEDTLS_RNG_GET , mg_mbed_rng, NULL
#else
#define MG_MBEDTLS_RNG_GET
#endif

static int mg_mbed_rng(void *ctx, unsigned char *buf, size_t len) {
  mg_random(buf, len);
  (void) ctx;
  return 0;
}

static bool mg_load_cert(struct mg_str str, mbedtls_x509_crt *p) {
  int rc;
  if (str.buf == NULL || str.buf[0] == '\0' || str.buf[0] == '*') return true;
  if (str.buf[0] == '-') str.len++;  // PEM, include trailing NUL
  if ((rc = mbedtls_x509_crt_parse(p, (uint8_t *) str.buf, str.len)) != 0) {
    MG_ERROR(("cert err %#x", -rc));
    return false;
  }
  return true;
}

static bool mg_load_key(struct mg_str str, mbedtls_pk_context *p) {
  int rc;
  if (str.buf == NULL || str.buf[0] == '\0' || str.buf[0] == '*') return true;
  if (str.buf[0] == '-') str.len++;  // PEM, include trailing NUL
  if ((rc = mbedtls_pk_parse_key(p, (uint8_t *) str.buf, str.len, NULL,
                                 0 MG_MBEDTLS_RNG_GET)) != 0) {
    MG_ERROR(("key err %#x", -rc));
    return false;
  }
  return true;
}

void mg_tls_free(struct mg_connection *c) {
  struct mg_tls *tls = (struct mg_tls *) c->tls;
  if (tls != NULL) {
    mbedtls_ssl_free(&tls->ssl);
    mbedtls_pk_free(&tls->pk);
    mbedtls_x509_crt_free(&tls->ca);
    mbedtls_x509_crt_free(&tls->cert);
    mbedtls_ssl_config_free(&tls->conf);
#ifdef MBEDTLS_SSL_SESSION_TICKETS
    mbedtls_ssl_ticket_free(&tls->ticket);
#endif
    free(tls);
    c->tls = NULL;
  }
}

static int mg_net_send(void *ctx, const unsigned char *buf, size_t len) {
  long n = mg_io_send((struct mg_connection *) ctx, buf, len);
  MG_VERBOSE(("%lu n=%ld e=%d", ((struct mg_connection *) ctx)->id, n, errno));
  if (n == MG_IO_WAIT) return MBEDTLS_ERR_SSL_WANT_WRITE;
  if (n == MG_IO_RESET) return MBEDTLS_ERR_NET_CONN_RESET;
  if (n == MG_IO_ERR) return MBEDTLS_ERR_NET_SEND_FAILED;
  return (int) n;
}

static int mg_net_recv(void *ctx, unsigned char *buf, size_t len) {
  long n = mg_io_recv((struct mg_connection *) ctx, buf, len);
  MG_VERBOSE(("%lu n=%ld", ((struct mg_connection *) ctx)->id, n));
  if (n == MG_IO_WAIT) return MBEDTLS_ERR_SSL_WANT_WRITE;
  if (n == MG_IO_RESET) return MBEDTLS_ERR_NET_CONN_RESET;
  if (n == MG_IO_ERR) return MBEDTLS_ERR_NET_RECV_FAILED;
  return (int) n;
}

void mg_tls_handshake(struct mg_connection *c) {
  struct mg_tls *tls = (struct mg_tls *) c->tls;
  int rc = mbedtls_ssl_handshake(&tls->ssl);
  if (rc == 0) {  // Success
    MG_DEBUG(("%lu success", c->id));
    c->is_tls_hs = 0;
    mg_call(c, MG_EV_TLS_HS, NULL);
  } else if (rc == MBEDTLS_ERR_SSL_WANT_READ ||
             rc == MBEDTLS_ERR_SSL_WANT_WRITE) {  // Still pending
    MG_VERBOSE(("%lu pending, %d%d %d (-%#x)", c->id, c->is_connecting,
                c->is_tls_hs, rc, -rc));
  } else {
    mg_error(c, "TLS handshake: -%#x", -rc);  // Error
  }
}

static void debug_cb(void *c, int lev, const char *s, int n, const char *s2) {
  n = (int) strlen(s2) - 1;
  MG_INFO(("%lu %d %.*s", ((struct mg_connection *) c)->id, lev, n, s2));
  (void) s;
}

void mg_tls_init(struct mg_connection *c, const struct mg_tls_opts *opts) {
  struct mg_tls *tls = (struct mg_tls *) calloc(1, sizeof(*tls));
  int rc = 0;
  c->tls = tls;
  if (c->tls == NULL) {
    mg_error(c, "TLS OOM");
    goto fail;
  }
  if (c->is_listening) goto fail;
  MG_DEBUG(("%lu Setting TLS", c->id));
  MG_PROF_ADD(c, "mbedtls_init_start");
#if defined(MBEDTLS_VERSION_NUMBER) && MBEDTLS_VERSION_NUMBER >= 0x03000000 && \
    defined(MBEDTLS_PSA_CRYPTO_C)
  psa_crypto_init();  // https://github.com/Mbed-TLS/mbedtls/issues/9072#issuecomment-2084845711
#endif
  mbedtls_ssl_init(&tls->ssl);
  mbedtls_ssl_config_init(&tls->conf);
  mbedtls_x509_crt_init(&tls->ca);
  mbedtls_x509_crt_init(&tls->cert);
  mbedtls_pk_init(&tls->pk);
  mbedtls_ssl_conf_dbg(&tls->conf, debug_cb, c);
#if defined(MG_MBEDTLS_DEBUG_LEVEL)
  mbedtls_debug_set_threshold(MG_MBEDTLS_DEBUG_LEVEL);
#endif
  if ((rc = mbedtls_ssl_config_defaults(
           &tls->conf,
           c->is_client ? MBEDTLS_SSL_IS_CLIENT : MBEDTLS_SSL_IS_SERVER,
           MBEDTLS_SSL_TRANSPORT_STREAM, MBEDTLS_SSL_PRESET_DEFAULT)) != 0) {
    mg_error(c, "tls defaults %#x", -rc);
    goto fail;
  }
  mbedtls_ssl_conf_rng(&tls->conf, mg_mbed_rng, c);

  if (opts->ca.len == 0 || mg_strcmp(opts->ca, mg_str("*")) == 0) {
    // NOTE: MBEDTLS_SSL_VERIFY_NONE is not supported for TLS1.3 on client side
    // See https://github.com/Mbed-TLS/mbedtls/issues/7075
    mbedtls_ssl_conf_authmode(&tls->conf, MBEDTLS_SSL_VERIFY_NONE);
  } else {
    if (mg_load_cert(opts->ca, &tls->ca) == false) goto fail;
    mbedtls_ssl_conf_ca_chain(&tls->conf, &tls->ca, NULL);
    if (c->is_client && opts->name.buf != NULL && opts->name.buf[0] != '\0') {
      char *host = mg_mprintf("%.*s", opts->name.len, opts->name.buf);
      mbedtls_ssl_set_hostname(&tls->ssl, host);
      MG_DEBUG(("%lu hostname verification: %s", c->id, host));
      free(host);
    }
    mbedtls_ssl_conf_authmode(&tls->conf, MBEDTLS_SSL_VERIFY_REQUIRED);
  }
  if (!mg_load_cert(opts->cert, &tls->cert)) goto fail;
  if (!mg_load_key(opts->key, &tls->pk)) goto fail;
  if (tls->cert.version &&
      (rc = mbedtls_ssl_conf_own_cert(&tls->conf, &tls->cert, &tls->pk)) != 0) {
    mg_error(c, "own cert %#x", -rc);
    goto fail;
  }

#ifdef MBEDTLS_SSL_SESSION_TICKETS
  mbedtls_ssl_conf_session_tickets_cb(
      &tls->conf, mbedtls_ssl_ticket_write, mbedtls_ssl_ticket_parse,
      &((struct mg_tls_ctx *) c->mgr->tls_ctx)->tickets);
#endif

  if ((rc = mbedtls_ssl_setup(&tls->ssl, &tls->conf)) != 0) {
    mg_error(c, "setup err %#x", -rc);
    goto fail;
  }
  c->is_tls = 1;
  c->is_tls_hs = 1;
  mbedtls_ssl_set_bio(&tls->ssl, c, mg_net_send, mg_net_recv, 0);
  MG_PROF_ADD(c, "mbedtls_init_end");
  return;
fail:
  mg_tls_free(c);
}

size_t mg_tls_pending(struct mg_connection *c) {
  struct mg_tls *tls = (struct mg_tls *) c->tls;
  return tls == NULL ? 0 : mbedtls_ssl_get_bytes_avail(&tls->ssl);
}

long mg_tls_recv(struct mg_connection *c, void *buf, size_t len) {
  struct mg_tls *tls = (struct mg_tls *) c->tls;
  long n = mbedtls_ssl_read(&tls->ssl, (unsigned char *) buf, len);
  if (n == MBEDTLS_ERR_SSL_WANT_READ || n == MBEDTLS_ERR_SSL_WANT_WRITE)
    return MG_IO_WAIT;
#if defined(MBEDTLS_ERR_SSL_RECEIVED_NEW_SESSION_TICKET)
  if (n == MBEDTLS_ERR_SSL_RECEIVED_NEW_SESSION_TICKET) {
    return MG_IO_WAIT;
  }
#endif
  if (n <= 0) return MG_IO_ERR;
  return n;
}

long mg_tls_send(struct mg_connection *c, const void *buf, size_t len) {
  struct mg_tls *tls = (struct mg_tls *) c->tls;
  long n;
  bool was_throttled = c->is_tls_throttled;  // see #3074
  n = was_throttled ? mbedtls_ssl_write(&tls->ssl, tls->throttled_buf,
                                        tls->throttled_len) /* flush old data */
                    : mbedtls_ssl_write(&tls->ssl, (unsigned char *) buf,
                                        len);  // encrypt current data
  c->is_tls_throttled =
      (n == MBEDTLS_ERR_SSL_WANT_READ || n == MBEDTLS_ERR_SSL_WANT_WRITE);
  if (was_throttled) return MG_IO_WAIT;  // flushed throttled data instead
  if (c->is_tls_throttled) return len;  // already encripted that when throttled
  if (n <= 0) return MG_IO_ERR;
  return n;
}

void mg_tls_ctx_init(struct mg_mgr *mgr) {
  struct mg_tls_ctx *ctx = (struct mg_tls_ctx *) calloc(1, sizeof(*ctx));
  if (ctx == NULL) {
    MG_ERROR(("TLS context init OOM"));
  } else {
#ifdef MBEDTLS_SSL_SESSION_TICKETS
    int rc;
    mbedtls_ssl_ticket_init(&ctx->tickets);
    if ((rc = mbedtls_ssl_ticket_setup(&ctx->tickets, mg_mbed_rng, NULL,
                                       MBEDTLS_CIPHER_AES_128_GCM, 86400)) !=
        0) {
      MG_ERROR((" mbedtls_ssl_ticket_setup %#x", -rc));
    }
#endif
    mgr->tls_ctx = ctx;
  }
}

void mg_tls_ctx_free(struct mg_mgr *mgr) {
  struct mg_tls_ctx *ctx = (struct mg_tls_ctx *) mgr->tls_ctx;
  if (ctx != NULL) {
#ifdef MBEDTLS_SSL_SESSION_TICKETS
    mbedtls_ssl_ticket_free(&ctx->tickets);
#endif
    free(ctx);
    mgr->tls_ctx = NULL;
  }
}
#endif

#ifdef MG_ENABLE_LINES
#line 1 "src/tls_openssl.c"
#endif



#if MG_TLS == MG_TLS_OPENSSL || MG_TLS == MG_TLS_WOLFSSL

static int tls_err_cb(const char *s, size_t len, void *c) {
  int n = (int) len - 1;
  MG_ERROR(("%lu %.*s", ((struct mg_connection *) c)->id, n, s));
  return 0;  // undocumented
}

static int mg_tls_err(struct mg_connection *c, struct mg_tls *tls, int res) {
  int err = SSL_get_error(tls->ssl, res);
  // We've just fetched the last error from the queue.
  // Now we need to clear the error queue. If we do not, then the following
  // can happen (actually reported):
  //  - A new connection is accept()-ed with cert error (e.g. self-signed cert)
  //  - Since all accept()-ed connections share listener's context,
  //  - *ALL* SSL accepted connection report read error on the next poll cycle.
  //    Thus a single errored connection can close all the rest, unrelated ones.
  // Clearing the error keeps the shared SSL_CTX in an OK state.

  if (err != 0) ERR_print_errors_cb(tls_err_cb, c);
  ERR_clear_error();
  if (err == SSL_ERROR_WANT_READ) return 0;
  if (err == SSL_ERROR_WANT_WRITE) return 0;
  return err;
}

static STACK_OF(X509_INFO) * load_ca_certs(struct mg_str ca) {
  BIO *bio = BIO_new_mem_buf(ca.buf, (int) ca.len);
  STACK_OF(X509_INFO) *certs =
      bio ? PEM_X509_INFO_read_bio(bio, NULL, NULL, NULL) : NULL;
  if (bio) BIO_free(bio);
  return certs;
}

static bool add_ca_certs(SSL_CTX *ctx, STACK_OF(X509_INFO) * certs) {
  int i;
  X509_STORE *cert_store = SSL_CTX_get_cert_store(ctx);
  for (i = 0; i < sk_X509_INFO_num(certs); i++) {
    X509_INFO *cert_info = sk_X509_INFO_value(certs, i);
    if (cert_info->x509 && !X509_STORE_add_cert(cert_store, cert_info->x509))
      return false;
  }
  return true;
}

static EVP_PKEY *load_key(struct mg_str s) {
  BIO *bio = BIO_new_mem_buf(s.buf, (int) (long) s.len);
  EVP_PKEY *key = bio ? PEM_read_bio_PrivateKey(bio, NULL, 0, NULL) : NULL;
  if (bio) BIO_free(bio);
  return key;
}

static X509 *load_cert(struct mg_str s) {
  BIO *bio = BIO_new_mem_buf(s.buf, (int) (long) s.len);
  X509 *cert = bio == NULL ? NULL
               : s.buf[0] == '-'
                   ? PEM_read_bio_X509(bio, NULL, NULL, NULL)  // PEM
                   : d2i_X509_bio(bio, NULL);                  // DER
  if (bio) BIO_free(bio);
  return cert;
}

static long mg_bio_ctrl(BIO *b, int cmd, long larg, void *pargs) {
  long ret = 0;
  if (cmd == BIO_CTRL_PUSH) ret = 1;
  if (cmd == BIO_CTRL_POP) ret = 1;
  if (cmd == BIO_CTRL_FLUSH) ret = 1;
#if MG_TLS == MG_TLS_OPENSSL
  if (cmd == BIO_C_SET_NBIO) ret = 1;
#endif
  // MG_DEBUG(("%d -> %ld", cmd, ret));
  (void) b, (void) cmd, (void) larg, (void) pargs;
  return ret;
}

static int mg_bio_read(BIO *bio, char *buf, int len) {
  struct mg_connection *c = (struct mg_connection *) BIO_get_data(bio);
  long res = mg_io_recv(c, buf, (size_t) len);
  // MG_DEBUG(("%p %d %ld", buf, len, res));
  len = res > 0 ? (int) res : -1;
  if (res == MG_IO_WAIT) BIO_set_retry_read(bio);
  return len;
}

static int mg_bio_write(BIO *bio, const char *buf, int len) {
  struct mg_connection *c = (struct mg_connection *) BIO_get_data(bio);
  long res = mg_io_send(c, buf, (size_t) len);
  // MG_DEBUG(("%p %d %ld", buf, len, res));
  len = res > 0 ? (int) res : -1;
  if (res == MG_IO_WAIT) BIO_set_retry_write(bio);
  return len;
}

#ifdef MG_TLS_SSLKEYLOGFILE
static void ssl_keylog_cb(const SSL *ssl, const char *line) {
  char *keylogfile = getenv("SSLKEYLOGFILE");
  if (keylogfile == NULL) {
    return;
  }
  FILE *f = fopen(keylogfile, "a");
  fprintf(f, "%s\n", line);
  fflush(f);
  fclose(f);
}
#endif

void mg_tls_free(struct mg_connection *c) {
  struct mg_tls *tls = (struct mg_tls *) c->tls;
  if (tls == NULL) return;
  SSL_free(tls->ssl);
  SSL_CTX_free(tls->ctx);
  BIO_meth_free(tls->bm);
  free(tls);
  c->tls = NULL;
}

void mg_tls_init(struct mg_connection *c, const struct mg_tls_opts *opts) {
  struct mg_tls *tls = (struct mg_tls *) calloc(1, sizeof(*tls));
  const char *id = "mongoose";
  static unsigned char s_initialised = 0;
  BIO *bio = NULL;
  int rc;
  c->tls = tls;
  if (tls == NULL) {
    mg_error(c, "TLS OOM");
    goto fail;
  }

  if (!s_initialised) {
    SSL_library_init();
    s_initialised++;
  }
  MG_DEBUG(("%lu Setting TLS", c->id));
  tls->ctx = c->is_client ? SSL_CTX_new(TLS_client_method())
                          : SSL_CTX_new(TLS_server_method());
  if (tls->ctx == NULL) {
    mg_error(c, "SSL_CTX_new");
    goto fail;
  }
#ifdef MG_TLS_SSLKEYLOGFILE
  SSL_CTX_set_keylog_callback(tls->ctx, ssl_keylog_cb);
#endif
  if ((tls->ssl = SSL_new(tls->ctx)) == NULL) {
    mg_error(c, "SSL_new");
    goto fail;
  }
  SSL_set_session_id_context(tls->ssl, (const uint8_t *) id,
                             (unsigned) strlen(id));
  // Disable deprecated protocols
  SSL_set_options(tls->ssl, SSL_OP_NO_SSLv2);
  SSL_set_options(tls->ssl, SSL_OP_NO_SSLv3);
  SSL_set_options(tls->ssl, SSL_OP_NO_TLSv1);
  SSL_set_options(tls->ssl, SSL_OP_NO_TLSv1_1);
#ifdef MG_ENABLE_OPENSSL_NO_COMPRESSION
  SSL_set_options(tls->ssl, SSL_OP_NO_COMPRESSION);
#endif
#ifdef MG_ENABLE_OPENSSL_CIPHER_SERVER_PREFERENCE
  SSL_set_options(tls->ssl, SSL_OP_CIPHER_SERVER_PREFERENCE);
#endif

#if MG_TLS == MG_TLS_WOLFSSL && !defined(OPENSSL_COMPATIBLE_DEFAULTS)
  if (opts->ca.len == 0 || mg_strcmp(opts->ca, mg_str("*")) == 0) {
    // Older versions require that either the CA is loaded or SSL_VERIFY_NONE
    // explicitly set
    SSL_set_verify(tls->ssl, SSL_VERIFY_NONE, NULL);
  }
#endif
  if (opts->ca.buf != NULL && opts->ca.buf[0] != '\0') {
    SSL_set_verify(tls->ssl, SSL_VERIFY_PEER | SSL_VERIFY_FAIL_IF_NO_PEER_CERT,
                   NULL);
    STACK_OF(X509_INFO) *certs = load_ca_certs(opts->ca);
    rc = add_ca_certs(tls->ctx, certs);
    sk_X509_INFO_pop_free(certs, X509_INFO_free);
    if (!rc) {
      mg_error(c, "CA err");
      goto fail;
    }
  }
  if (opts->cert.buf != NULL && opts->cert.buf[0] != '\0') {
    X509 *cert = load_cert(opts->cert);
    rc = cert == NULL ? 0 : SSL_use_certificate(tls->ssl, cert);
    X509_free(cert);
    if (cert == NULL || rc != 1) {
      mg_error(c, "CERT err %d", mg_tls_err(c, tls, rc));
      goto fail;
    }
  }
  if (opts->key.buf != NULL && opts->key.buf[0] != '\0') {
    EVP_PKEY *key = load_key(opts->key);
    rc = key == NULL ? 0 : SSL_use_PrivateKey(tls->ssl, key);
    EVP_PKEY_free(key);
    if (key == NULL || rc != 1) {
      mg_error(c, "KEY err %d", mg_tls_err(c, tls, rc));
      goto fail;
    }
  }

  SSL_set_mode(tls->ssl, SSL_MODE_ACCEPT_MOVING_WRITE_BUFFER);
#if MG_TLS == MG_TLS_OPENSSL && OPENSSL_VERSION_NUMBER > 0x10002000L
  (void) SSL_set_ecdh_auto(tls->ssl, 1);
#endif
#if OPENSSL_VERSION_NUMBER >= 0x10100000L
  if (opts->name.len > 0) {
    char *s = mg_mprintf("%.*s", (int) opts->name.len, opts->name.buf);
#if MG_TLS != MG_TLS_WOLFSSL || LIBWOLFSSL_VERSION_HEX >= 0x05005002
    SSL_set1_host(tls->ssl, s);
#else
    X509_VERIFY_PARAM_set1_host(SSL_get0_param(tls->ssl), s, 0);
#endif
    SSL_set_tlsext_host_name(tls->ssl, s);
    free(s);
  }
#endif
#if MG_TLS == MG_TLS_WOLFSSL
  tls->bm = BIO_meth_new(0, "bio_mg");
#else
  tls->bm = BIO_meth_new(BIO_get_new_index() | BIO_TYPE_SOURCE_SINK, "bio_mg");
#endif
  BIO_meth_set_write(tls->bm, mg_bio_write);
  BIO_meth_set_read(tls->bm, mg_bio_read);
  BIO_meth_set_ctrl(tls->bm, mg_bio_ctrl);

  bio = BIO_new(tls->bm);
  BIO_set_data(bio, c);
  SSL_set_bio(tls->ssl, bio, bio);

  c->is_tls = 1;
  c->is_tls_hs = 1;
  MG_DEBUG(("%lu SSL %s OK", c->id, c->is_accepted ? "accept" : "client"));
  return;
fail:
  mg_tls_free(c);
}

void mg_tls_handshake(struct mg_connection *c) {
  struct mg_tls *tls = (struct mg_tls *) c->tls;
  int rc = c->is_client ? SSL_connect(tls->ssl) : SSL_accept(tls->ssl);
  if (rc == 1) {
    MG_DEBUG(("%lu success", c->id));
    c->is_tls_hs = 0;
    mg_call(c, MG_EV_TLS_HS, NULL);
  } else {
    int code = mg_tls_err(c, tls, rc);
    if (code != 0) mg_error(c, "tls hs: rc %d, err %d", rc, code);
  }
}

size_t mg_tls_pending(struct mg_connection *c) {
  struct mg_tls *tls = (struct mg_tls *) c->tls;
  return tls == NULL ? 0 : (size_t) SSL_pending(tls->ssl);
}

long mg_tls_recv(struct mg_connection *c, void *buf, size_t len) {
  struct mg_tls *tls = (struct mg_tls *) c->tls;
  int n = SSL_read(tls->ssl, buf, (int) len);
  if (n < 0 && mg_tls_err(c, tls, n) == 0) return MG_IO_WAIT;
  if (n <= 0) return MG_IO_ERR;
  return n;
}

long mg_tls_send(struct mg_connection *c, const void *buf, size_t len) {
  struct mg_tls *tls = (struct mg_tls *) c->tls;
  int n = SSL_write(tls->ssl, buf, (int) len);
  if (n < 0 && mg_tls_err(c, tls, n) == 0) return MG_IO_WAIT;
  if (n <= 0) return MG_IO_ERR;
  return n;
}

void mg_tls_ctx_init(struct mg_mgr *mgr) {
  (void) mgr;
}

void mg_tls_ctx_free(struct mg_mgr *mgr) {
  (void) mgr;
}
#endif

#ifdef MG_ENABLE_LINES
#line 1 "src/tls_rsa.c"
#endif



#if MG_TLS == MG_TLS_BUILTIN

#define NS_INTERNAL static
typedef struct _bigint bigint; /**< An alias for _bigint */

/*
 * Copyright (c) 2007, Cameron Rich
 *
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * * Redistributions of source code must retain the above copyright notice,
 *   this list of conditions and the following disclaimer.
 * * Redistributions in binary form must reproduce the above copyright notice,
 *   this list of conditions and the following disclaimer in the documentation
 *   and/or other materials provided with the distribution.
 * * Neither the name of the axTLS project nor the names of its contributors
 *   may be used to endorse or promote products derived from this software
 *   without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/* Maintain a number of precomputed variables when doing reduction */
#define BIGINT_M_OFFSET 0 /**< Normal modulo offset. */
#define BIGINT_P_OFFSET 1 /**< p modulo offset. */
#define BIGINT_Q_OFFSET 2 /**< q module offset. */
#define BIGINT_NUM_MODS 3 /**< The number of modulus constants used. */

/* Architecture specific functions for big ints */
#if defined(CONFIG_INTEGER_8BIT)
#define COMP_RADIX 256U     /**< Max component + 1 */
#define COMP_MAX 0xFFFFU    /**< (Max dbl comp -1) */
#define COMP_BIT_SIZE 8     /**< Number of bits in a component. */
#define COMP_BYTE_SIZE 1    /**< Number of bytes in a component. */
#define COMP_NUM_NIBBLES 2  /**< Used For diagnostics only. */
typedef uint8_t comp;       /**< A single precision component. */
typedef uint16_t long_comp; /**< A double precision component. */
typedef int16_t slong_comp; /**< A signed double precision component. */
#elif defined(CONFIG_INTEGER_16BIT)
#define COMP_RADIX 65536U    /**< Max component + 1 */
#define COMP_MAX 0xFFFFFFFFU /**< (Max dbl comp -1) */
#define COMP_BIT_SIZE 16     /**< Number of bits in a component. */
#define COMP_BYTE_SIZE 2     /**< Number of bytes in a component. */
#define COMP_NUM_NIBBLES 4   /**< Used For diagnostics only. */
typedef uint16_t comp;            /**< A single precision component. */
typedef uint32_t long_comp;       /**< A double precision component. */
typedef int32_t slong_comp;       /**< A signed double precision component. */
#else                        /* regular 32 bit */
#ifdef WIN32
#define COMP_RADIX 4294967296i64
#define COMP_MAX 0xFFFFFFFFFFFFFFFFui64
#else
#define COMP_RADIX 4294967296       /**< Max component + 1 */
#define COMP_MAX 0xFFFFFFFFFFFFFFFF /**< (Max dbl comp -1) */
#endif
#define COMP_BIT_SIZE 32   /**< Number of bits in a component. */
#define COMP_BYTE_SIZE 4   /**< Number of bytes in a component. */
#define COMP_NUM_NIBBLES 8 /**< Used For diagnostics only. */
typedef uint32_t comp;      /**< A single precision component. */
typedef uint64_t long_comp; /**< A double precision component. */
typedef int64_t slong_comp; /**< A signed double precision component. */
#endif

/**
 * @struct  _bigint
 * @brief A big integer basic object
 */
struct _bigint {
  struct _bigint *next; /**< The next bigint in the cache. */
  short size;           /**< The number of components in this bigint. */
  short max_comps;      /**< The heapsize allocated for this bigint */
  int refs;             /**< An internal reference count. */
  comp *comps;          /**< A ptr to the actual component data */
};

/**
 * Maintains the state of the cache, and a number of variables used in
 * reduction.
 */
struct _BI_CTX /**< A big integer "session" context. */
    {
  bigint *active_list;             /**< Bigints currently used. */
  bigint *free_list;               /**< Bigints not used. */
  bigint *bi_radix;                /**< The radix used. */
  bigint *bi_mod[BIGINT_NUM_MODS]; /**< modulus */

#if defined(CONFIG_BIGINT_MONTGOMERY)
  bigint *bi_RR_mod_m[BIGINT_NUM_MODS]; /**< R^2 mod m */
  bigint *bi_R_mod_m[BIGINT_NUM_MODS];  /**< R mod m */
  comp N0_dash[BIGINT_NUM_MODS];
#elif defined(CONFIG_BIGINT_BARRETT)
  bigint *bi_mu[BIGINT_NUM_MODS]; /**< Storage for mu */
#endif
  bigint *bi_normalised_mod[BIGINT_NUM_MODS]; /**< Normalised mod storage. */
  bigint **g;                                 /**< Used by sliding-window. */
  int window;       /**< The size of the sliding window */
  int active_count; /**< Number of active bigints. */
  int free_count;   /**< Number of free bigints. */

#ifdef CONFIG_BIGINT_MONTGOMERY
  uint8_t use_classical; /**< Use classical reduction. */
#endif
  uint8_t mod_offset; /**< The mod offset we are using */
};
typedef struct _BI_CTX BI_CTX;

#if !defined(MAX)
#define MAX(a, b) ((a) > (b) ? (a) : (b))
#define MIN(a, b)  ((a) < (b) ? (a) : (b))
#endif

#define PERMANENT 0x7FFF55AA /**< A magic number for permanents. */

/*
 * Copyright (c) 2007, Cameron Rich
 *
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * * Redistributions of source code must retain the above copyright notice,
 *   this list of conditions and the following disclaimer.
 * * Redistributions in binary form must reproduce the above copyright notice,
 *   this list of conditions and the following disclaimer in the documentation
 *   and/or other materials provided with the distribution.
 * * Neither the name of the axTLS project nor the names of its contributors
 *   may be used to endorse or promote products derived from this software
 *   without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

NS_INTERNAL BI_CTX *bi_initialize(void);
//NS_INTERNAL void bi_terminate(BI_CTX *ctx);
NS_INTERNAL void bi_permanent(bigint *bi);
NS_INTERNAL void bi_depermanent(bigint *bi);
//NS_INTERNAL void bi_clear_cache(BI_CTX *ctx);
NS_INTERNAL void bi_free(BI_CTX *ctx, bigint *bi);
NS_INTERNAL bigint *bi_copy(bigint *bi);
NS_INTERNAL bigint *bi_clone(BI_CTX *ctx, const bigint *bi);
NS_INTERNAL void bi_export(BI_CTX *ctx, bigint *bi, uint8_t *data, int size);
NS_INTERNAL bigint *bi_import(BI_CTX *ctx, const uint8_t *data, int len);
NS_INTERNAL bigint *int_to_bi(BI_CTX *ctx, comp i);

/* the functions that actually do something interesting */
NS_INTERNAL bigint *bi_add(BI_CTX *ctx, bigint *bia, bigint *bib);
NS_INTERNAL bigint *bi_subtract(BI_CTX *ctx, bigint *bia, bigint *bib,
                                int *is_negative);
NS_INTERNAL bigint *bi_divide(BI_CTX *ctx, bigint *bia, bigint *bim,
                              int is_mod);
NS_INTERNAL bigint *bi_multiply(BI_CTX *ctx, bigint *bia, bigint *bib);
NS_INTERNAL bigint *bi_mod_power(BI_CTX *ctx, bigint *bi, bigint *biexp);
#if 0
NS_INTERNAL bigint *bi_mod_power2(BI_CTX *ctx, bigint *bi,
			bigint *bim, bigint *biexp);
#endif
NS_INTERNAL int bi_compare(bigint *bia, bigint *bib);
NS_INTERNAL void bi_set_mod(BI_CTX *ctx, bigint *bim, int mod_offset);
//NS_INTERNAL void bi_free_mod(BI_CTX *ctx, int mod_offset);

#ifdef CONFIG_SSL_FULL_MODE
NS_INTERNAL void bi_print(const char *label, bigint *bi);
NS_INTERNAL bigint *bi_str_import(BI_CTX *ctx, const char *data);
#endif

/**
 * @def bi_mod
 * Find the residue of B. bi_set_mod() must be called before hand.
 */
#define bi_mod(A, B) bi_divide(A, B, ctx->bi_mod[ctx->mod_offset], 1)

/**
 * bi_residue() is technically the same as bi_mod(), but it uses the
 * appropriate reduction technique (which is bi_mod() when doing classical
 * reduction).
 */
#if defined(CONFIG_BIGINT_MONTGOMERY)
#define bi_residue(A, B) bi_mont(A, B)
NS_INTERNAL bigint *bi_mont(BI_CTX *ctx, bigint *bixy);
#elif defined(CONFIG_BIGINT_BARRETT)
#define bi_residue(A, B) bi_barrett(A, B)
NS_INTERNAL bigint *bi_barrett(BI_CTX *ctx, bigint *bi);
#else /* if defined(CONFIG_BIGINT_CLASSICAL) */
#define bi_residue(A, B) bi_mod(A, B)
#endif

#ifdef CONFIG_BIGINT_SQUARE
NS_INTERNAL bigint *bi_square(BI_CTX *ctx, bigint *bi);
#else
#define bi_square(A, B) bi_multiply(A, bi_copy(B), B)
#endif

//NS_INTERNAL bigint *bi_crt(BI_CTX *ctx, bigint *bi, bigint *dP, bigint *dQ,
//                           bigint *p, bigint *q, bigint *qInv);

/*
 * Copyright (c) 2007, Cameron Rich
 *
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * * Redistributions of source code must retain the above copyright notice,
 *   this list of conditions and the following disclaimer.
 * * Redistributions in binary form must reproduce the above copyright notice,
 *   this list of conditions and the following disclaimer in the documentation
 *   and/or other materials provided with the distribution.
 * * Neither the name of the axTLS project nor the names of its contributors
 *   may be used to endorse or promote products derived from this software
 *   without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/**
 * @defgroup bigint_api Big Integer API
 * @brief The bigint implementation as used by the axTLS project.
 *
 * The bigint library is for RSA encryption/decryption as well as signing.
 * This code tries to minimise use of malloc/free by maintaining a small
 * cache. A bigint context may maintain state by being made "permanent".
 * It be be later released with a bi_depermanent() and bi_free() call.
 *
 * It supports the following reduction techniques:
 * - Classical
 * - Barrett
 * - Montgomery
 *
 * It also implements the following:
 * - Karatsuba multiplication
 * - Squaring
 * - Sliding window exponentiation
 * - Chinese Remainder Theorem (implemented in rsa.c).
 *
 * All the algorithms used are pretty standard, and designed for different
 * data bus sizes. Negative numbers are not dealt with at all, so a subtraction
 * may need to be tested for negativity.
 *
 * This library steals some ideas from Jef Poskanzer
 * <http://cs.marlboro.edu/term/cs-fall02/algorithms/crypto/RSA/bigint>
 * and GMP <http://www.swox.com/gmp>. It gets most of its implementation
 * detail from "The Handbook of Applied Cryptography"
 * <http://www.cacr.math.uwaterloo.ca/hac/about/chap14.pdf>
 * @{
 */

#define V1 v->comps[v->size - 1]                     /**< v1 for division */
#define V2 v->comps[v->size - 2]                     /**< v2 for division */
#define U(j) tmp_u->comps[tmp_u->size - j - 1]       /**< uj for division */
#define Q(j) quotient->comps[quotient->size - j - 1] /**< qj for division */

static bigint *bi_int_multiply(BI_CTX *ctx, bigint *bi, comp i);
static bigint *bi_int_divide(BI_CTX *ctx, bigint *biR, comp denom);
static bigint *alloc(BI_CTX *ctx, int size);
static bigint *trim(bigint *bi);
static void more_comps(bigint *bi, int n);
#if defined(CONFIG_BIGINT_KARATSUBA) || defined(CONFIG_BIGINT_BARRETT) || \
    defined(CONFIG_BIGINT_MONTGOMERY)
static bigint *comp_right_shift(bigint *biR, int num_shifts);
static bigint *comp_left_shift(bigint *biR, int num_shifts);
#endif

#ifdef CONFIG_BIGINT_CHECK_ON
static void check(const bigint *bi);
#else
#define check(A) /**< disappears in normal production mode */
#endif

/**
 * @brief Start a new bigint context.
 * @return A bigint context.
 */
NS_INTERNAL BI_CTX *bi_initialize(void) {
  /* calloc() sets everything to zero */
  BI_CTX *ctx = (BI_CTX *) calloc(1, sizeof(BI_CTX));

  /* the radix */
  ctx->bi_radix = alloc(ctx, 2);
  ctx->bi_radix->comps[0] = 0;
  ctx->bi_radix->comps[1] = 1;
  bi_permanent(ctx->bi_radix);
  return ctx;
}

#if 0
/**
 * @brief Close the bigint context and free any resources.
 *
 * Free up any used memory - a check is done if all objects were not
 * properly freed.
 * @param ctx [in]   The bigint session context.
 */
NS_INTERNAL void bi_terminate(BI_CTX *ctx) {
  bi_depermanent(ctx->bi_radix);
  bi_free(ctx, ctx->bi_radix);

  if (ctx->active_count != 0) {
#ifdef CONFIG_SSL_FULL_MODE
    printf("bi_terminate: there were %d un-freed bigints\n", ctx->active_count);
#endif
    abort();
  }

  bi_clear_cache(ctx);
  free(ctx);
}

/**
 *@brief Clear the memory cache.
 */
NS_INTERNAL void bi_clear_cache(BI_CTX *ctx) {
  bigint *p, *pn;

  if (ctx->free_list == NULL) return;

  for (p = ctx->free_list; p != NULL; p = pn) {
    pn = p->next;
    free(p->comps);
    free(p);
  }

  ctx->free_count = 0;
  ctx->free_list = NULL;
}
#endif

/**
 * @brief Increment the number of references to this object.
 * It does not do a full copy.
 * @param bi [in]   The bigint to copy.
 * @return A reference to the same bigint.
 */
NS_INTERNAL bigint *bi_copy(bigint *bi) {
  check(bi);
  if (bi->refs != PERMANENT) bi->refs++;
  return bi;
}

/**
 * @brief Simply make a bigint object "unfreeable" if bi_free() is called on it.
 *
 * For this object to be freed, bi_depermanent() must be called.
 * @param bi [in]   The bigint to be made permanent.
 */
NS_INTERNAL void bi_permanent(bigint *bi) {
  check(bi);
  if (bi->refs != 1) {
#ifdef CONFIG_SSL_FULL_MODE
    printf("bi_permanent: refs was not 1\n");
#endif
    abort();
  }

  bi->refs = PERMANENT;
}

/**
 * @brief Take a permanent object and make it eligible for freedom.
 * @param bi [in]   The bigint to be made back to temporary.
 */
NS_INTERNAL void bi_depermanent(bigint *bi) {
  check(bi);
  if (bi->refs != PERMANENT) {
#ifdef CONFIG_SSL_FULL_MODE
    printf("bi_depermanent: bigint was not permanent\n");
#endif
    abort();
  }

  bi->refs = 1;
}

/**
 * @brief Free a bigint object so it can be used again.
 *
 * The memory itself it not actually freed, just tagged as being available
 * @param ctx [in]   The bigint session context.
 * @param bi [in]    The bigint to be freed.
 */
NS_INTERNAL void bi_free(BI_CTX *ctx, bigint *bi) {
  check(bi);
  if (bi->refs == PERMANENT) {
    return;
  }

  if (--bi->refs > 0) {
    return;
  }

  bi->next = ctx->free_list;
  ctx->free_list = bi;
  ctx->free_count++;

  if (--ctx->active_count < 0) {
#ifdef CONFIG_SSL_FULL_MODE
    printf(
        "bi_free: active_count went negative "
        "- double-freed bigint?\n");
#endif
    abort();
  }
}

/**
 * @brief Convert an (unsigned) integer into a bigint.
 * @param ctx [in]   The bigint session context.
 * @param i [in]     The (unsigned) integer to be converted.
 *
 */
NS_INTERNAL bigint *int_to_bi(BI_CTX *ctx, comp i) {
  bigint *biR = alloc(ctx, 1);
  biR->comps[0] = i;
  return biR;
}

/**
 * @brief Do a full copy of the bigint object.
 * @param ctx [in]   The bigint session context.
 * @param bi  [in]   The bigint object to be copied.
 */
NS_INTERNAL bigint *bi_clone(BI_CTX *ctx, const bigint *bi) {
  bigint *biR = alloc(ctx, bi->size);
  check(bi);
  memcpy(biR->comps, bi->comps, (size_t) bi->size * COMP_BYTE_SIZE);
  return biR;
}

/**
 * @brief Perform an addition operation between two bigints.
 * @param ctx [in]  The bigint session context.
 * @param bia [in]  A bigint.
 * @param bib [in]  Another bigint.
 * @return The result of the addition.
 */
NS_INTERNAL bigint *bi_add(BI_CTX *ctx, bigint *bia, bigint *bib) {
  int n;
  comp carry = 0;
  comp *pa, *pb;

  check(bia);
  check(bib);

  n = MAX(bia->size, bib->size);
  more_comps(bia, n + 1);
  more_comps(bib, n);
  pa = bia->comps;
  pb = bib->comps;

  do {
    comp sl, rl, cy1;
    sl = *pa + *pb++;
    rl = sl + carry;
    cy1 = sl < *pa;
    carry = cy1 | (rl < sl);
    *pa++ = rl;
  } while (--n != 0);

  *pa = carry; /* do overflow */
  bi_free(ctx, bib);
  return trim(bia);
}

/**
 * @brief Perform a subtraction operation between two bigints.
 * @param ctx [in]  The bigint session context.
 * @param bia [in]  A bigint.
 * @param bib [in]  Another bigint.
 * @param is_negative [out] If defined, indicates that the result was negative.
 * is_negative may be null.
 * @return The result of the subtraction. The result is always positive.
 */
NS_INTERNAL bigint *bi_subtract(BI_CTX *ctx, bigint *bia, bigint *bib,
                                int *is_negative) {
  int n = bia->size;
  comp *pa, *pb, carry = 0;

  check(bia);
  check(bib);

  more_comps(bib, n);
  pa = bia->comps;
  pb = bib->comps;

  do {
    comp sl, rl, cy1;
    sl = *pa - *pb++;
    rl = sl - carry;
    cy1 = sl > *pa;
    carry = cy1 | (rl > sl);
    *pa++ = rl;
  } while (--n != 0);

  if (is_negative) /* indicate a negative result */
  {
    *is_negative = (int) carry;
  }

  bi_free(ctx, trim(bib)); /* put bib back to the way it was */
  return trim(bia);
}

/**
 * Perform a multiply between a bigint an an (unsigned) integer
 */
static bigint *bi_int_multiply(BI_CTX *ctx, bigint *bia, comp b) {
  int j = 0, n = bia->size;
  bigint *biR = alloc(ctx, n + 1);
  comp carry = 0;
  comp *r = biR->comps;
  comp *a = bia->comps;

  check(bia);

  /* clear things to start with */
  memset(r, 0, (size_t) ((n + 1) * COMP_BYTE_SIZE));

  do {
    long_comp tmp = *r + (long_comp) a[j] * b + carry;
    *r++ = (comp) tmp; /* downsize */
    carry = (comp)(tmp >> COMP_BIT_SIZE);
  } while (++j < n);

  *r = carry;
  bi_free(ctx, bia);
  return trim(biR);
}

/**
 * @brief Does both division and modulo calculations.
 *
 * Used extensively when doing classical reduction.
 * @param ctx [in]  The bigint session context.
 * @param u [in]    A bigint which is the numerator.
 * @param v [in]    Either the denominator or the modulus depending on the mode.
 * @param is_mod [n] Determines if this is a normal division (0) or a reduction
 * (1).
 * @return  The result of the division/reduction.
 */
NS_INTERNAL bigint *bi_divide(BI_CTX *ctx, bigint *u, bigint *v, int is_mod) {
  int n = v->size, m = u->size - n;
  int j = 0, orig_u_size = u->size;
  uint8_t mod_offset = ctx->mod_offset;
  comp d;
  bigint *quotient, *tmp_u;
  comp q_dash;

  check(u);
  check(v);

  /* if doing reduction and we are < mod, then return mod */
  if (is_mod && bi_compare(v, u) > 0) {
    bi_free(ctx, v);
    return u;
  }

  quotient = alloc(ctx, m + 1);
  tmp_u = alloc(ctx, n + 1);
  v = trim(v); /* make sure we have no leading 0's */
  d = (comp)((long_comp) COMP_RADIX / (V1 + 1));

  /* clear things to start with */
  memset(quotient->comps, 0, (size_t) ((quotient->size) * COMP_BYTE_SIZE));

  /* normalise */
  if (d > 1) {
    u = bi_int_multiply(ctx, u, d);

    if (is_mod) {
      v = ctx->bi_normalised_mod[mod_offset];
    } else {
      v = bi_int_multiply(ctx, v, d);
    }
  }

  if (orig_u_size == u->size) /* new digit position u0 */
  {
    more_comps(u, orig_u_size + 1);
  }

  do {
    /* get a temporary short version of u */
    memcpy(tmp_u->comps, &u->comps[u->size - n - 1 - j],
           (size_t) (n + 1) * COMP_BYTE_SIZE);

    /* calculate q' */
    if (U(0) == V1) {
      q_dash = COMP_RADIX - 1;
    } else {
      q_dash = (comp)(((long_comp) U(0) * COMP_RADIX + U(1)) / V1);

      if (v->size > 1 && V2) {
        /* we are implementing the following:
        if (V2*q_dash > (((U(0)*COMP_RADIX + U(1) -
                q_dash*V1)*COMP_RADIX) + U(2))) ... */
        comp inner = (comp)((long_comp) COMP_RADIX * U(0) + U(1) -
                            (long_comp) q_dash * V1);
        if ((long_comp) V2 * q_dash > (long_comp) inner * COMP_RADIX + U(2)) {
          q_dash--;
        }
      }
    }

    /* multiply and subtract */
    if (q_dash) {
      int is_negative;
      tmp_u = bi_subtract(ctx, tmp_u, bi_int_multiply(ctx, bi_copy(v), q_dash),
                          &is_negative);
      more_comps(tmp_u, n + 1);

      Q(j) = q_dash;

      /* add back */
      if (is_negative) {
        Q(j)--;
        tmp_u = bi_add(ctx, tmp_u, bi_copy(v));

        /* lop off the carry */
        tmp_u->size--;
        v->size--;
      }
    } else {
      Q(j) = 0;
    }

    /* copy back to u */
    memcpy(&u->comps[u->size - n - 1 - j], tmp_u->comps,
           (size_t) (n + 1) * COMP_BYTE_SIZE);
  } while (++j <= m);

  bi_free(ctx, tmp_u);
  bi_free(ctx, v);

  if (is_mod) /* get the remainder */
  {
    bi_free(ctx, quotient);
    return bi_int_divide(ctx, trim(u), d);
  } else /* get the quotient */
  {
    bi_free(ctx, u);
    return trim(quotient);
  }
}

/*
 * Perform an integer divide on a bigint.
 */
static bigint *bi_int_divide(BI_CTX *ctx, bigint *biR, comp denom) {
  int i = biR->size - 1;
  long_comp r = 0;

  (void) ctx;
  check(biR);

  do {
    r = (r << COMP_BIT_SIZE) + biR->comps[i];
    biR->comps[i] = (comp)(r / denom);
    r %= denom;
  } while (--i >= 0);

  return trim(biR);
}

#ifdef CONFIG_BIGINT_MONTGOMERY
/**
 * There is a need for the value of integer N' such that B^-1(B-1)-N^-1N'=1,
 * where B^-1(B-1) mod N=1. Actually, only the least significant part of
 * N' is needed, hence the definition N0'=N' mod b. We reproduce below the
 * simple algorithm from an article by Dusse and Kaliski to efficiently
 * find N0' from N0 and b */
static comp modular_inverse(bigint *bim) {
  int i;
  comp t = 1;
  comp two_2_i_minus_1 = 2; /* 2^(i-1) */
  long_comp two_2_i = 4;    /* 2^i */
  comp N = bim->comps[0];

  for (i = 2; i <= COMP_BIT_SIZE; i++) {
    if ((long_comp) N * t % two_2_i >= two_2_i_minus_1) {
      t += two_2_i_minus_1;
    }

    two_2_i_minus_1 <<= 1;
    two_2_i <<= 1;
  }

  return (comp)(COMP_RADIX - t);
}
#endif

#if defined(CONFIG_BIGINT_KARATSUBA) || defined(CONFIG_BIGINT_BARRETT) || \
    defined(CONFIG_BIGINT_MONTGOMERY)
/**
 * Take each component and shift down (in terms of components)
 */
static bigint *comp_right_shift(bigint *biR, int num_shifts) {
  int i = biR->size - num_shifts;
  comp *x = biR->comps;
  comp *y = &biR->comps[num_shifts];

  check(biR);

  if (i <= 0) /* have we completely right shifted? */
  {
    biR->comps[0] = 0; /* return 0 */
    biR->size = 1;
    return biR;
  }

  do {
    *x++ = *y++;
  } while (--i > 0);

  biR->size -= num_shifts;
  return biR;
}

/**
 * Take each component and shift it up (in terms of components)
 */
static bigint *comp_left_shift(bigint *biR, int num_shifts) {
  int i = biR->size - 1;
  comp *x, *y;

  check(biR);

  if (num_shifts <= 0) {
    return biR;
  }

  more_comps(biR, biR->size + num_shifts);

  x = &biR->comps[i + num_shifts];
  y = &biR->comps[i];

  do {
    *x-- = *y--;
  } while (i--);

  memset(biR->comps, 0, (size_t) (num_shifts * COMP_BYTE_SIZE)); /* zero LS comps */
  return biR;
}
#endif

/**
 * @brief Allow a binary sequence to be imported as a bigint.
 * @param ctx [in]  The bigint session context.
 * @param data [in] The data to be converted.
 * @param size [in] The number of bytes of data.
 * @return A bigint representing this data.
 */
NS_INTERNAL bigint *bi_import(BI_CTX *ctx, const uint8_t *data, int size) {
  bigint *biR = alloc(ctx, (size + COMP_BYTE_SIZE - 1) / COMP_BYTE_SIZE);
  int i, j = 0, offset = 0;

  memset(biR->comps, 0, (size_t) (biR->size * COMP_BYTE_SIZE));

  for (i = size - 1; i >= 0; i--) {
    biR->comps[offset] += (comp) data[i] << (j * 8);

    if (++j == COMP_BYTE_SIZE) {
      j = 0;
      offset++;
    }
  }

  return trim(biR);
}

#ifdef CONFIG_SSL_FULL_MODE
/**
 * @brief The testharness uses this code to import text hex-streams and
 * convert them into bigints.
 * @param ctx [in]  The bigint session context.
 * @param data [in] A string consisting of hex characters. The characters must
 * be in upper case.
 * @return A bigint representing this data.
 */
NS_INTERNAL bigint *bi_str_import(BI_CTX *ctx, const char *data) {
  int size = strlen(data);
  bigint *biR = alloc(ctx, (size + COMP_NUM_NIBBLES - 1) / COMP_NUM_NIBBLES);
  int i, j = 0, offset = 0;
  memset(biR->comps, 0, (size_t) (biR->size * COMP_BYTE_SIZE));

  for (i = size - 1; i >= 0; i--) {
    int num = (data[i] <= '9') ? (data[i] - '0') : (data[i] - 'A' + 10);
    biR->comps[offset] += num << (j * 4);

    if (++j == COMP_NUM_NIBBLES) {
      j = 0;
      offset++;
    }
  }

  return biR;
}

NS_INTERNAL void bi_print(const char *label, bigint *x) {
  int i, j;

  if (x == NULL) {
    printf("%s: (null)\n", label);
    return;
  }

  printf("%s: (size %d)\n", label, x->size);
  for (i = x->size - 1; i >= 0; i--) {
    for (j = COMP_NUM_NIBBLES - 1; j >= 0; j--) {
      comp mask = 0x0f << (j * 4);
      comp num = (x->comps[i] & mask) >> (j * 4);
      putc((num <= 9) ? (num + '0') : (num + 'A' - 10), stdout);
    }
  }

  printf("\n");
}
#endif

/**
 * @brief Take a bigint and convert it into a byte sequence.
 *
 * This is useful after a decrypt operation.
 * @param ctx [in]  The bigint session context.
 * @param x [in]  The bigint to be converted.
 * @param data [out] The converted data as a byte stream.
 * @param size [in] The maximum size of the byte stream. Unused bytes will be
 * zeroed.
 */
NS_INTERNAL void bi_export(BI_CTX *ctx, bigint *x, uint8_t *data, int size) {
  int i, j, k = size - 1;

  check(x);
  memset(data, 0, (size_t) size); /* ensure all leading 0's are cleared */

  for (i = 0; i < x->size; i++) {
    for (j = 0; j < COMP_BYTE_SIZE; j++) {
      comp mask = (comp) 0xff << (j * 8);
      int num = (int) (x->comps[i] & mask) >> (j * 8);
      data[k--] = (uint8_t) num;

      if (k < 0) {
        goto buf_done;
      }
    }
  }
buf_done:

  bi_free(ctx, x);
}

/**
 * @brief Pre-calculate some of the expensive steps in reduction.
 *
 * This function should only be called once (normally when a session starts).
 * When the session is over, bi_free_mod() should be called. bi_mod_power()
 * relies on this function being called.
 * @param ctx [in]  The bigint session context.
 * @param bim [in]  The bigint modulus that will be used.
 * @param mod_offset [in] There are three moduluii that can be stored - the
 * standard modulus, and its two primes p and q. This offset refers to which
 * modulus we are referring to.
 * @see bi_free_mod(), bi_mod_power().
 */
NS_INTERNAL void bi_set_mod(BI_CTX *ctx, bigint *bim, int mod_offset) {
  int k = bim->size;
  comp d = (comp)((long_comp) COMP_RADIX / (bim->comps[k - 1] + 1));
#ifdef CONFIG_BIGINT_MONTGOMERY
  bigint *R, *R2;
#endif

  ctx->bi_mod[mod_offset] = bim;
  bi_permanent(ctx->bi_mod[mod_offset]);
  ctx->bi_normalised_mod[mod_offset] = bi_int_multiply(ctx, bim, d);
  bi_permanent(ctx->bi_normalised_mod[mod_offset]);

#if defined(CONFIG_BIGINT_MONTGOMERY)
  /* set montgomery variables */
  R = comp_left_shift(bi_clone(ctx, ctx->bi_radix), k - 1);      /* R */
  R2 = comp_left_shift(bi_clone(ctx, ctx->bi_radix), k * 2 - 1); /* R^2 */
  ctx->bi_RR_mod_m[mod_offset] = bi_mod(ctx, R2);                /* R^2 mod m */
  ctx->bi_R_mod_m[mod_offset] = bi_mod(ctx, R);                  /* R mod m */

  bi_permanent(ctx->bi_RR_mod_m[mod_offset]);
  bi_permanent(ctx->bi_R_mod_m[mod_offset]);

  ctx->N0_dash[mod_offset] = modular_inverse(ctx->bi_mod[mod_offset]);

#elif defined(CONFIG_BIGINT_BARRETT)
  ctx->bi_mu[mod_offset] =
      bi_divide(ctx, comp_left_shift(bi_clone(ctx, ctx->bi_radix), k * 2 - 1),
                ctx->bi_mod[mod_offset], 0);
  bi_permanent(ctx->bi_mu[mod_offset]);
#endif
}

#if 0
/**
 * @brief Used when cleaning various bigints at the end of a session.
 * @param ctx [in]  The bigint session context.
 * @param mod_offset [in] The offset to use.
 * @see bi_set_mod().
 */
void bi_free_mod(BI_CTX *ctx, int mod_offset) {
  bi_depermanent(ctx->bi_mod[mod_offset]);
  bi_free(ctx, ctx->bi_mod[mod_offset]);
#if defined(CONFIG_BIGINT_MONTGOMERY)
  bi_depermanent(ctx->bi_RR_mod_m[mod_offset]);
  bi_depermanent(ctx->bi_R_mod_m[mod_offset]);
  bi_free(ctx, ctx->bi_RR_mod_m[mod_offset]);
  bi_free(ctx, ctx->bi_R_mod_m[mod_offset]);
#elif defined(CONFIG_BIGINT_BARRETT)
  bi_depermanent(ctx->bi_mu[mod_offset]);
  bi_free(ctx, ctx->bi_mu[mod_offset]);
#endif
  bi_depermanent(ctx->bi_normalised_mod[mod_offset]);
  bi_free(ctx, ctx->bi_normalised_mod[mod_offset]);
}
#endif

/**
 * Perform a standard multiplication between two bigints.
 *
 * Barrett reduction has no need for some parts of the product, so ignore bits
 * of the multiply. This routine gives Barrett its big performance
 * improvements over Classical/Montgomery reduction methods.
 */
static bigint *regular_multiply(BI_CTX *ctx, bigint *bia, bigint *bib,
                                int inner_partial, int outer_partial) {
  int i = 0, j;
  int n = bia->size;
  int t = bib->size;
  bigint *biR = alloc(ctx, n + t);
  comp *sr = biR->comps;
  comp *sa = bia->comps;
  comp *sb = bib->comps;

  check(bia);
  check(bib);

  /* clear things to start with */
  memset(biR->comps, 0, (size_t) ((n + t) * COMP_BYTE_SIZE));

  do {
    long_comp tmp;
    comp carry = 0;
    int r_index = i;
    j = 0;

    if (outer_partial && outer_partial - i > 0 && outer_partial < n) {
      r_index = outer_partial - 1;
      j = outer_partial - i - 1;
    }

    do {
      if (inner_partial && r_index >= inner_partial) {
        break;
      }

      tmp = sr[r_index] + ((long_comp) sa[j]) * sb[i] + carry;
      sr[r_index++] = (comp) tmp; /* downsize */
      carry = (comp) (tmp >> COMP_BIT_SIZE);
    } while (++j < n);

    sr[r_index] = carry;
  } while (++i < t);

  bi_free(ctx, bia);
  bi_free(ctx, bib);
  return trim(biR);
}

#ifdef CONFIG_BIGINT_KARATSUBA
/*
 * Karatsuba improves on regular multiplication due to only 3 multiplications
 * being done instead of 4. The additional additions/subtractions are O(N)
 * rather than O(N^2) and so for big numbers it saves on a few operations
 */
static bigint *karatsuba(BI_CTX *ctx, bigint *bia, bigint *bib, int is_square) {
  bigint *x0, *x1;
  bigint *p0, *p1, *p2;
  int m;

  if (is_square) {
    m = (bia->size + 1) / 2;
  } else {
    m = (MAX(bia->size, bib->size) + 1) / 2;
  }

  x0 = bi_clone(ctx, bia);
  x0->size = m;
  x1 = bi_clone(ctx, bia);
  comp_right_shift(x1, m);
  bi_free(ctx, bia);

  /* work out the 3 partial products */
  if (is_square) {
    p0 = bi_square(ctx, bi_copy(x0));
    p2 = bi_square(ctx, bi_copy(x1));
    p1 = bi_square(ctx, bi_add(ctx, x0, x1));
  } else /* normal multiply */
  {
    bigint *y0, *y1;
    y0 = bi_clone(ctx, bib);
    y0->size = m;
    y1 = bi_clone(ctx, bib);
    comp_right_shift(y1, m);
    bi_free(ctx, bib);

    p0 = bi_multiply(ctx, bi_copy(x0), bi_copy(y0));
    p2 = bi_multiply(ctx, bi_copy(x1), bi_copy(y1));
    p1 = bi_multiply(ctx, bi_add(ctx, x0, x1), bi_add(ctx, y0, y1));
  }

  p1 = bi_subtract(ctx, bi_subtract(ctx, p1, bi_copy(p2), NULL), bi_copy(p0),
                   NULL);

  comp_left_shift(p1, m);
  comp_left_shift(p2, 2 * m);
  return bi_add(ctx, p1, bi_add(ctx, p0, p2));
}
#endif

/**
 * @brief Perform a multiplication operation between two bigints.
 * @param ctx [in]  The bigint session context.
 * @param bia [in]  A bigint.
 * @param bib [in]  Another bigint.
 * @return The result of the multiplication.
 */
NS_INTERNAL bigint *bi_multiply(BI_CTX *ctx, bigint *bia, bigint *bib) {
  check(bia);
  check(bib);

#ifdef CONFIG_BIGINT_KARATSUBA
  if (MIN(bia->size, bib->size) < MUL_KARATSUBA_THRESH) {
    return regular_multiply(ctx, bia, bib, 0, 0);
  }

  return karatsuba(ctx, bia, bib, 0);
#else
  return regular_multiply(ctx, bia, bib, 0, 0);
#endif
}

#ifdef CONFIG_BIGINT_SQUARE
/*
 * Perform the actual square operion. It takes into account overflow.
 */
static bigint *regular_square(BI_CTX *ctx, bigint *bi) {
  int t = bi->size;
  int i = 0, j;
  bigint *biR = alloc(ctx, t * 2 + 1);
  comp *w = biR->comps;
  comp *x = bi->comps;
  long_comp carry;
  memset(w, 0, biR->size * COMP_BYTE_SIZE);

  do {
    long_comp tmp = w[2 * i] + (long_comp) x[i] * x[i];
    w[2 * i] = (comp) tmp;
    carry = tmp >> COMP_BIT_SIZE;

    for (j = i + 1; j < t; j++) {
      uint8_t c = 0;
      long_comp xx = (long_comp) x[i] * x[j];
      if ((COMP_MAX - xx) < xx) c = 1;

      tmp = (xx << 1);

      if ((COMP_MAX - tmp) < w[i + j]) c = 1;

      tmp += w[i + j];

      if ((COMP_MAX - tmp) < carry) c = 1;

      tmp += carry;
      w[i + j] = (comp) tmp;
      carry = tmp >> COMP_BIT_SIZE;

      if (c) carry += COMP_RADIX;
    }

    tmp = w[i + t] + carry;
    w[i + t] = (comp) tmp;
    w[i + t + 1] = tmp >> COMP_BIT_SIZE;
  } while (++i < t);

  bi_free(ctx, bi);
  return trim(biR);
}

/**
 * @brief Perform a square operation on a bigint.
 * @param ctx [in]  The bigint session context.
 * @param bia [in]  A bigint.
 * @return The result of the multiplication.
 */
NS_INTERNAL bigint *bi_square(BI_CTX *ctx, bigint *bia) {
  check(bia);

#ifdef CONFIG_BIGINT_KARATSUBA
  if (bia->size < SQU_KARATSUBA_THRESH) {
    return regular_square(ctx, bia);
  }

  return karatsuba(ctx, bia, NULL, 1);
#else
  return regular_square(ctx, bia);
#endif
}
#endif

/**
 * @brief Compare two bigints.
 * @param bia [in]  A bigint.
 * @param bib [in]  Another bigint.
 * @return -1 if smaller, 1 if larger and 0 if equal.
 */
NS_INTERNAL int bi_compare(bigint *bia, bigint *bib) {
  int r, i;

  check(bia);
  check(bib);

  if (bia->size > bib->size)
    r = 1;
  else if (bia->size < bib->size)
    r = -1;
  else {
    comp *a = bia->comps;
    comp *b = bib->comps;

    /* Same number of components.  Compare starting from the high end
     * and working down. */
    r = 0;
    i = bia->size - 1;

    do {
      if (a[i] > b[i]) {
        r = 1;
        break;
      } else if (a[i] < b[i]) {
        r = -1;
        break;
      }
    } while (--i >= 0);
  }

  return r;
}

/*
 * Allocate and zero more components.  Does not consume bi.
 */
static void more_comps(bigint *bi, int n) {
  if (n > bi->max_comps) {
    int max = MAX(bi->max_comps * 2, n);
    void *p = calloc(1, (size_t) max * COMP_BYTE_SIZE);
    if (p != NULL && bi->size > 0) memcpy(p, bi->comps, (size_t) bi->max_comps * COMP_BYTE_SIZE);
    free(bi->comps);
    bi->max_comps = (short) max;
    bi->comps = (comp *) p;
  }

  if (n > bi->size) {
    memset(&bi->comps[bi->size], 0, (size_t) (n - bi->size) * COMP_BYTE_SIZE);
  }

  bi->size = (short) n;
}

/*
 * Make a new empty bigint. It may just use an old one if one is available.
 * Otherwise get one off the heap.
 */
static bigint *alloc(BI_CTX *ctx, int size) {
  bigint *biR;

  /* Can we recycle an old bigint? */
  if (ctx->free_list != NULL) {
    biR = ctx->free_list;
    ctx->free_list = biR->next;
    ctx->free_count--;

    if (biR->refs != 0) {
#ifdef CONFIG_SSL_FULL_MODE
      printf("alloc: refs was not 0\n");
#endif
      abort(); /* create a stack trace from a core dump */
    }

    more_comps(biR, size);
  } else {
    /* No free bigints available - create a new one. */
    biR = (bigint *) calloc(1, sizeof(bigint));
    biR->comps = (comp *) calloc(1, (size_t) size * COMP_BYTE_SIZE);
    biR->max_comps = (short) size; /* give some space to spare */
  }

  biR->size = (short) size;
  biR->refs = 1;
  biR->next = NULL;
  ctx->active_count++;
  return biR;
}

/*
 * Work out the highest '1' bit in an exponent. Used when doing sliding-window
 * exponentiation.
 */
static int find_max_exp_index(bigint *biexp) {
  int i = COMP_BIT_SIZE - 1;
  comp shift = COMP_RADIX / 2;
  comp test = biexp->comps[biexp->size - 1]; /* assume no leading zeroes */

  check(biexp);

  do {
    if (test & shift) {
      return i + (biexp->size - 1) * COMP_BIT_SIZE;
    }

    shift >>= 1;
  } while (i-- != 0);

  return -1; /* error - must have been a leading 0 */
}

/*
 * Is a particular bit is an exponent 1 or 0? Used when doing sliding-window
 * exponentiation.
 */
static int exp_bit_is_one(bigint *biexp, int offset) {
  comp test = biexp->comps[offset / COMP_BIT_SIZE];
  int num_shifts = offset % COMP_BIT_SIZE;
  comp shift = 1;
  int i;

  check(biexp);

  for (i = 0; i < num_shifts; i++) {
    shift <<= 1;
  }

  return (test & shift) != 0;
}

#ifdef CONFIG_BIGINT_CHECK_ON
/*
 * Perform a sanity check on bi.
 */
static void check(const bigint *bi) {
  if (bi->refs <= 0) {
    printf("check: zero or negative refs in bigint\n");
    abort();
  }

  if (bi->next != NULL) {
    printf(
        "check: attempt to use a bigint from "
        "the free list\n");
    abort();
  }
}
#endif

/*
 * Delete any leading 0's (and allow for 0).
 */
static bigint *trim(bigint *bi) {
  check(bi);

  while (bi->comps[bi->size - 1] == 0 && bi->size > 1) {
    bi->size--;
  }

  return bi;
}

#if defined(CONFIG_BIGINT_MONTGOMERY)
/**
 * @brief Perform a single montgomery reduction.
 * @param ctx [in]  The bigint session context.
 * @param bixy [in]  A bigint.
 * @return The result of the montgomery reduction.
 */
NS_INTERNAL bigint *bi_mont(BI_CTX *ctx, bigint *bixy) {
  int i = 0, n;
  uint8_t mod_offset = ctx->mod_offset;
  bigint *bim = ctx->bi_mod[mod_offset];
  comp mod_inv = ctx->N0_dash[mod_offset];

  check(bixy);

  if (ctx->use_classical) /* just use classical instead */
  {
    return bi_mod(ctx, bixy);
  }

  n = bim->size;

  do {
    bixy = bi_add(ctx, bixy,
                  comp_left_shift(
                      bi_int_multiply(ctx, bim, bixy->comps[i] * mod_inv), i));
  } while (++i < n);

  comp_right_shift(bixy, n);

  if (bi_compare(bixy, bim) >= 0) {
    bixy = bi_subtract(ctx, bixy, bim, NULL);
  }

  return bixy;
}

#elif defined(CONFIG_BIGINT_BARRETT)
/*
 * Stomp on the most significant components to give the illusion of a "mod base
 * radix" operation
 */
static bigint *comp_mod(bigint *bi, int mod) {
  check(bi);

  if (bi->size > mod) {
    bi->size = mod;
  }

  return bi;
}

/**
 * @brief Perform a single Barrett reduction.
 * @param ctx [in]  The bigint session context.
 * @param bi [in]  A bigint.
 * @return The result of the Barrett reduction.
 */
NS_INTERNAL bigint *bi_barrett(BI_CTX *ctx, bigint *bi) {
  bigint *q1, *q2, *q3, *r1, *r2, *r;
  uint8_t mod_offset = ctx->mod_offset;
  bigint *bim = ctx->bi_mod[mod_offset];
  int k = bim->size;

  check(bi);
  check(bim);

  /* use Classical method instead  - Barrett cannot help here */
  if (bi->size > k * 2) {
    return bi_mod(ctx, bi);
  }

  q1 = comp_right_shift(bi_clone(ctx, bi), k - 1);

  /* do outer partial multiply */
  q2 = regular_multiply(ctx, q1, ctx->bi_mu[mod_offset], 0, k - 1);
  q3 = comp_right_shift(q2, k + 1);
  r1 = comp_mod(bi, k + 1);

  /* do inner partial multiply */
  r2 = comp_mod(regular_multiply(ctx, q3, bim, k + 1, 0), k + 1);
  r = bi_subtract(ctx, r1, r2, NULL);

  /* if (r >= m) r = r - m; */
  if (bi_compare(r, bim) >= 0) {
    r = bi_subtract(ctx, r, bim, NULL);
  }

  return r;
}
#endif /* CONFIG_BIGINT_BARRETT */

#ifdef CONFIG_BIGINT_SLIDING_WINDOW
/*
 * Work out g1, g3, g5, g7... etc for the sliding-window algorithm
 */
static void precompute_slide_window(BI_CTX *ctx, int window, bigint *g1) {
  int k = 1, i;
  bigint *g2;

  for (i = 0; i < window - 1; i++) /* compute 2^(window-1) */
  {
    k <<= 1;
  }

  ctx->g = (bigint **) calloc(1, k * sizeof(bigint *));
  ctx->g[0] = bi_clone(ctx, g1);
  bi_permanent(ctx->g[0]);
  g2 = bi_residue(ctx, bi_square(ctx, ctx->g[0])); /* g^2 */

  for (i = 1; i < k; i++) {
    ctx->g[i] = bi_residue(ctx, bi_multiply(ctx, ctx->g[i - 1], bi_copy(g2)));
    bi_permanent(ctx->g[i]);
  }

  bi_free(ctx, g2);
  ctx->window = k;
}
#endif

/**
 * @brief Perform a modular exponentiation.
 *
 * This function requires bi_set_mod() to have been called previously. This is
 * one of the optimisations used for performance.
 * @param ctx [in]  The bigint session context.
 * @param bi  [in]  The bigint on which to perform the mod power operation.
 * @param biexp [in] The bigint exponent.
 * @return The result of the mod exponentiation operation
 * @see bi_set_mod().
 */
NS_INTERNAL bigint *bi_mod_power(BI_CTX *ctx, bigint *bi, bigint *biexp) {
  int i = find_max_exp_index(biexp), j, window_size = 1;
  bigint *biR = int_to_bi(ctx, 1);

#if defined(CONFIG_BIGINT_MONTGOMERY)
  uint8_t mod_offset = ctx->mod_offset;
  if (!ctx->use_classical) {
    /* preconvert */
    bi = bi_mont(ctx,
                 bi_multiply(ctx, bi, ctx->bi_RR_mod_m[mod_offset])); /* x' */
    bi_free(ctx, biR);
    biR = ctx->bi_R_mod_m[mod_offset]; /* A */
  }
#endif

  check(bi);
  check(biexp);

#ifdef CONFIG_BIGINT_SLIDING_WINDOW
  for (j = i; j > 32; j /= 5) /* work out an optimum size */
    window_size++;

  /* work out the slide constants */
  precompute_slide_window(ctx, window_size, bi);
#else /* just one constant */
  ctx->g = (bigint **) calloc(1, sizeof(bigint *));
  ctx->g[0] = bi_clone(ctx, bi);
  ctx->window = 1;
  bi_permanent(ctx->g[0]);
#endif

  /* if sliding-window is off, then only one bit will be done at a time and
   * will reduce to standard left-to-right exponentiation */
  do {
    if (exp_bit_is_one(biexp, i)) {
      int l = i - window_size + 1;
      int part_exp = 0;

      if (l < 0) /* LSB of exponent will always be 1 */
        l = 0;
      else {
        while (exp_bit_is_one(biexp, l) == 0) l++; /* go back up */
      }

      /* build up the section of the exponent */
      for (j = i; j >= l; j--) {
        biR = bi_residue(ctx, bi_square(ctx, biR));
        if (exp_bit_is_one(biexp, j)) part_exp++;

        if (j != l) part_exp <<= 1;
      }

      part_exp = (part_exp - 1) / 2; /* adjust for array */
      biR = bi_residue(ctx, bi_multiply(ctx, biR, ctx->g[part_exp]));
      i = l - 1;
    } else /* square it */
    {
      biR = bi_residue(ctx, bi_square(ctx, biR));
      i--;
    }
  } while (i >= 0);

  /* cleanup */
  for (i = 0; i < ctx->window; i++) {
    bi_depermanent(ctx->g[i]);
    bi_free(ctx, ctx->g[i]);
  }

  free(ctx->g);
  bi_free(ctx, bi);
  bi_free(ctx, biexp);
#if defined CONFIG_BIGINT_MONTGOMERY
  return ctx->use_classical ? biR : bi_mont(ctx, biR); /* convert back */
#else /* CONFIG_BIGINT_CLASSICAL or CONFIG_BIGINT_BARRETT */
  return biR;
#endif
}

#if 0
/**
 * @brief Use the Chinese Remainder Theorem to quickly perform RSA decrypts.
 *
 * @param ctx [in]  The bigint session context.
 * @param bi  [in]  The bigint to perform the exp/mod.
 * @param dP [in] CRT's dP bigint
 * @param dQ [in] CRT's dQ bigint
 * @param p [in] CRT's p bigint
 * @param q [in] CRT's q bigint
 * @param qInv [in] CRT's qInv bigint
 * @return The result of the CRT operation
 */
NS_INTERNAL bigint *bi_crt(BI_CTX *ctx, bigint *bi, bigint *dP, bigint *dQ,
                           bigint *p, bigint *q, bigint *qInv) {
  bigint *m1, *m2, *h;

/* Montgomery has a condition the 0 < x, y < m and these products violate
 * that condition. So disable Montgomery when using CRT */
#if defined(CONFIG_BIGINT_MONTGOMERY)
  ctx->use_classical = 1;
#endif
  ctx->mod_offset = BIGINT_P_OFFSET;
  m1 = bi_mod_power(ctx, bi_copy(bi), dP);

  ctx->mod_offset = BIGINT_Q_OFFSET;
  m2 = bi_mod_power(ctx, bi, dQ);

  h = bi_subtract(ctx, bi_add(ctx, m1, p), bi_copy(m2), NULL);
  h = bi_multiply(ctx, h, qInv);
  ctx->mod_offset = BIGINT_P_OFFSET;
  h = bi_residue(ctx, h);
#if defined(CONFIG_BIGINT_MONTGOMERY)
  ctx->use_classical = 0; /* reset for any further operation */
#endif
  return bi_add(ctx, m2, bi_multiply(ctx, q, h));
}
#endif

int mg_rsa_mod_pow(const uint8_t *mod, size_t modsz, const uint8_t *exp, size_t expsz, const uint8_t *msg, size_t msgsz, uint8_t *out, size_t outsz) {
	BI_CTX *bi_ctx = bi_initialize();
	bigint *n = bi_import(bi_ctx, mod, (int) modsz);
	bigint *e = bi_import(bi_ctx, exp, (int) expsz);
	bigint *h = bi_import(bi_ctx, msg, (int) msgsz);
	bi_set_mod(bi_ctx, n, 0);
	bigint *m1 = bi_mod_power(bi_ctx, h, e);
	bi_export(bi_ctx, m1, out, (int) outsz);
	bi_free(bi_ctx, n);
	bi_free(bi_ctx, e);
	bi_free(bi_ctx, h);
	bi_free(bi_ctx, m1);
	return 0;
}

#endif /* MG_TLS == MG_TLS_BUILTIN */

#ifdef MG_ENABLE_LINES
#line 1 "src/tls_uecc.c"
#endif
/* Copyright 2014, Kenneth MacKay. Licensed under the BSD 2-clause license. */




#if MG_TLS == MG_TLS_BUILTIN

#ifndef MG_UECC_RNG_MAX_TRIES
#define MG_UECC_RNG_MAX_TRIES 64
#endif

#if MG_UECC_ENABLE_VLI_API
#define MG_UECC_VLI_API
#else
#define MG_UECC_VLI_API static
#endif

#if (MG_UECC_PLATFORM == mg_uecc_avr) || (MG_UECC_PLATFORM == mg_uecc_arm) || \
    (MG_UECC_PLATFORM == mg_uecc_arm_thumb) ||                                \
    (MG_UECC_PLATFORM == mg_uecc_arm_thumb2)
#define MG_UECC_CONCATX(a, ...) a##__VA_ARGS__
#define MG_UECC_CONCAT(a, ...) MG_UECC_CONCATX(a, __VA_ARGS__)

#define STRX(a) #a
#define STR(a) STRX(a)

#define EVAL(...) EVAL1(EVAL1(EVAL1(EVAL1(__VA_ARGS__))))
#define EVAL1(...) EVAL2(EVAL2(EVAL2(EVAL2(__VA_ARGS__))))
#define EVAL2(...) EVAL3(EVAL3(EVAL3(EVAL3(__VA_ARGS__))))
#define EVAL3(...) EVAL4(EVAL4(EVAL4(EVAL4(__VA_ARGS__))))
#define EVAL4(...) __VA_ARGS__

#define DEC_1 0
#define DEC_2 1
#define DEC_3 2
#define DEC_4 3
#define DEC_5 4
#define DEC_6 5
#define DEC_7 6
#define DEC_8 7
#define DEC_9 8
#define DEC_10 9
#define DEC_11 10
#define DEC_12 11
#define DEC_13 12
#define DEC_14 13
#define DEC_15 14
#define DEC_16 15
#define DEC_17 16
#define DEC_18 17
#define DEC_19 18
#define DEC_20 19
#define DEC_21 20
#define DEC_22 21
#define DEC_23 22
#define DEC_24 23
#define DEC_25 24
#define DEC_26 25
#define DEC_27 26
#define DEC_28 27
#define DEC_29 28
#define DEC_30 29
#define DEC_31 30
#define DEC_32 31

#define DEC_(N) MG_UECC_CONCAT(DEC_, N)

#define SECOND_ARG(_, val, ...) val
#define SOME_CHECK_0 ~, 0
#define GET_SECOND_ARG(...) SECOND_ARG(__VA_ARGS__, SOME, )
#define SOME_OR_0(N) GET_SECOND_ARG(MG_UECC_CONCAT(SOME_CHECK_, N))

#define MG_UECC_EMPTY(...)
#define DEFER(...) __VA_ARGS__ MG_UECC_EMPTY()

#define REPEAT_NAME_0() REPEAT_0
#define REPEAT_NAME_SOME() REPEAT_SOME
#define REPEAT_0(...)
#define REPEAT_SOME(N, stuff) \
  DEFER(MG_UECC_CONCAT(REPEAT_NAME_, SOME_OR_0(DEC_(N))))()(DEC_(N), stuff) stuff
#define REPEAT(N, stuff) EVAL(REPEAT_SOME(N, stuff))

#define REPEATM_NAME_0() REPEATM_0
#define REPEATM_NAME_SOME() REPEATM_SOME
#define REPEATM_0(...)
#define REPEATM_SOME(N, macro) \
  macro(N) DEFER(MG_UECC_CONCAT(REPEATM_NAME_, SOME_OR_0(DEC_(N))))()(DEC_(N), macro)
#define REPEATM(N, macro) EVAL(REPEATM_SOME(N, macro))
#endif

// 

#if (MG_UECC_WORD_SIZE == 1)
#if MG_UECC_SUPPORTS_secp160r1
#define MG_UECC_MAX_WORDS 21 /* Due to the size of curve_n. */
#endif
#if MG_UECC_SUPPORTS_secp192r1
#undef MG_UECC_MAX_WORDS
#define MG_UECC_MAX_WORDS 24
#endif
#if MG_UECC_SUPPORTS_secp224r1
#undef MG_UECC_MAX_WORDS
#define MG_UECC_MAX_WORDS 28
#endif
#if (MG_UECC_SUPPORTS_secp256r1 || MG_UECC_SUPPORTS_secp256k1)
#undef MG_UECC_MAX_WORDS
#define MG_UECC_MAX_WORDS 32
#endif
#elif (MG_UECC_WORD_SIZE == 4)
#if MG_UECC_SUPPORTS_secp160r1
#define MG_UECC_MAX_WORDS 6 /* Due to the size of curve_n. */
#endif
#if MG_UECC_SUPPORTS_secp192r1
#undef MG_UECC_MAX_WORDS
#define MG_UECC_MAX_WORDS 6
#endif
#if MG_UECC_SUPPORTS_secp224r1
#undef MG_UECC_MAX_WORDS
#define MG_UECC_MAX_WORDS 7
#endif
#if (MG_UECC_SUPPORTS_secp256r1 || MG_UECC_SUPPORTS_secp256k1)
#undef MG_UECC_MAX_WORDS
#define MG_UECC_MAX_WORDS 8
#endif
#elif (MG_UECC_WORD_SIZE == 8)
#if MG_UECC_SUPPORTS_secp160r1
#define MG_UECC_MAX_WORDS 3
#endif
#if MG_UECC_SUPPORTS_secp192r1
#undef MG_UECC_MAX_WORDS
#define MG_UECC_MAX_WORDS 3
#endif
#if MG_UECC_SUPPORTS_secp224r1
#undef MG_UECC_MAX_WORDS
#define MG_UECC_MAX_WORDS 4
#endif
#if (MG_UECC_SUPPORTS_secp256r1 || MG_UECC_SUPPORTS_secp256k1)
#undef MG_UECC_MAX_WORDS
#define MG_UECC_MAX_WORDS 4
#endif
#endif /* MG_UECC_WORD_SIZE */

#define BITS_TO_WORDS(num_bits)                                \
  ((wordcount_t) ((num_bits + ((MG_UECC_WORD_SIZE * 8) - 1)) / \
                  (MG_UECC_WORD_SIZE * 8)))
#define BITS_TO_BYTES(num_bits) ((num_bits + 7) / 8)

struct MG_UECC_Curve_t {
  wordcount_t num_words;
  wordcount_t num_bytes;
  bitcount_t num_n_bits;
  mg_uecc_word_t p[MG_UECC_MAX_WORDS];
  mg_uecc_word_t n[MG_UECC_MAX_WORDS];
  mg_uecc_word_t G[MG_UECC_MAX_WORDS * 2];
  mg_uecc_word_t b[MG_UECC_MAX_WORDS];
  void (*double_jacobian)(mg_uecc_word_t *X1, mg_uecc_word_t *Y1,
                          mg_uecc_word_t *Z1, MG_UECC_Curve curve);
#if MG_UECC_SUPPORT_COMPRESSED_POINT
  void (*mod_sqrt)(mg_uecc_word_t *a, MG_UECC_Curve curve);
#endif
  void (*x_side)(mg_uecc_word_t *result, const mg_uecc_word_t *x,
                 MG_UECC_Curve curve);
#if (MG_UECC_OPTIMIZATION_LEVEL > 0)
  void (*mmod_fast)(mg_uecc_word_t *result, mg_uecc_word_t *product);
#endif
};

#if MG_UECC_VLI_NATIVE_LITTLE_ENDIAN
static void bcopy(uint8_t *dst, const uint8_t *src, unsigned num_bytes) {
  while (0 != num_bytes) {
    num_bytes--;
    dst[num_bytes] = src[num_bytes];
  }
}
#endif

static cmpresult_t mg_uecc_vli_cmp_unsafe(const mg_uecc_word_t *left,
                                          const mg_uecc_word_t *right,
                                          wordcount_t num_words);

#if (MG_UECC_PLATFORM == mg_uecc_arm ||       \
     MG_UECC_PLATFORM == mg_uecc_arm_thumb || \
     MG_UECC_PLATFORM == mg_uecc_arm_thumb2)

#endif

#if (MG_UECC_PLATFORM == mg_uecc_avr)

#endif

#ifndef asm_clear
#define asm_clear 0
#endif
#ifndef asm_set
#define asm_set 0
#endif
#ifndef asm_add
#define asm_add 0
#endif
#ifndef asm_sub
#define asm_sub 0
#endif
#ifndef asm_mult
#define asm_mult 0
#endif
#ifndef asm_rshift1
#define asm_rshift1 0
#endif
#ifndef asm_mmod_fast_secp256r1
#define asm_mmod_fast_secp256r1 0
#endif

#if defined(default_RNG_defined) && default_RNG_defined
static MG_UECC_RNG_Function g_rng_function = &default_RNG;
#else
static MG_UECC_RNG_Function g_rng_function = 0;
#endif

void mg_uecc_set_rng(MG_UECC_RNG_Function rng_function) {
  g_rng_function = rng_function;
}

MG_UECC_RNG_Function mg_uecc_get_rng(void) {
  return g_rng_function;
}

int mg_uecc_curve_private_key_size(MG_UECC_Curve curve) {
  return BITS_TO_BYTES(curve->num_n_bits);
}

int mg_uecc_curve_public_key_size(MG_UECC_Curve curve) {
  return 2 * curve->num_bytes;
}

#if !asm_clear
MG_UECC_VLI_API void mg_uecc_vli_clear(mg_uecc_word_t *vli,
                                       wordcount_t num_words) {
  wordcount_t i;
  for (i = 0; i < num_words; ++i) {
    vli[i] = 0;
  }
}
#endif /* !asm_clear */

/* Constant-time comparison to zero - secure way to compare long integers */
/* Returns 1 if vli == 0, 0 otherwise. */
MG_UECC_VLI_API mg_uecc_word_t mg_uecc_vli_isZero(const mg_uecc_word_t *vli,
                                                  wordcount_t num_words) {
  mg_uecc_word_t bits = 0;
  wordcount_t i;
  for (i = 0; i < num_words; ++i) {
    bits |= vli[i];
  }
  return (bits == 0);
}

/* Returns nonzero if bit 'bit' of vli is set. */
MG_UECC_VLI_API mg_uecc_word_t mg_uecc_vli_testBit(const mg_uecc_word_t *vli,
                                                   bitcount_t bit) {
  return (vli[bit >> MG_UECC_WORD_BITS_SHIFT] &
          ((mg_uecc_word_t) 1 << (bit & MG_UECC_WORD_BITS_MASK)));
}

/* Counts the number of words in vli. */
static wordcount_t vli_numDigits(const mg_uecc_word_t *vli,
                                 const wordcount_t max_words) {
  wordcount_t i;
  /* Search from the end until we find a non-zero digit.
     We do it in reverse because we expect that most digits will be nonzero. */
  for (i = max_words - 1; i >= 0 && vli[i] == 0; --i) {
  }

  return (i + 1);
}

/* Counts the number of bits required to represent vli. */
MG_UECC_VLI_API bitcount_t mg_uecc_vli_numBits(const mg_uecc_word_t *vli,
                                               const wordcount_t max_words) {
  mg_uecc_word_t i;
  mg_uecc_word_t digit;

  wordcount_t num_digits = vli_numDigits(vli, max_words);
  if (num_digits == 0) {
    return 0;
  }

  digit = vli[num_digits - 1];
  for (i = 0; digit; ++i) {
    digit >>= 1;
  }

  return (((bitcount_t) ((num_digits - 1) << MG_UECC_WORD_BITS_SHIFT)) +
          (bitcount_t) i);
}

/* Sets dest = src. */
#if !asm_set
MG_UECC_VLI_API void mg_uecc_vli_set(mg_uecc_word_t *dest,
                                     const mg_uecc_word_t *src,
                                     wordcount_t num_words) {
  wordcount_t i;
  for (i = 0; i < num_words; ++i) {
    dest[i] = src[i];
  }
}
#endif /* !asm_set */

/* Returns sign of left - right. */
static cmpresult_t mg_uecc_vli_cmp_unsafe(const mg_uecc_word_t *left,
                                          const mg_uecc_word_t *right,
                                          wordcount_t num_words) {
  wordcount_t i;
  for (i = num_words - 1; i >= 0; --i) {
    if (left[i] > right[i]) {
      return 1;
    } else if (left[i] < right[i]) {
      return -1;
    }
  }
  return 0;
}

/* Constant-time comparison function - secure way to compare long integers */
/* Returns one if left == right, zero otherwise. */
MG_UECC_VLI_API mg_uecc_word_t mg_uecc_vli_equal(const mg_uecc_word_t *left,
                                                 const mg_uecc_word_t *right,
                                                 wordcount_t num_words) {
  mg_uecc_word_t diff = 0;
  wordcount_t i;
  for (i = num_words - 1; i >= 0; --i) {
    diff |= (left[i] ^ right[i]);
  }
  return (diff == 0);
}

MG_UECC_VLI_API mg_uecc_word_t mg_uecc_vli_sub(mg_uecc_word_t *result,
                                               const mg_uecc_word_t *left,
                                               const mg_uecc_word_t *right,
                                               wordcount_t num_words);

/* Returns sign of left - right, in constant time. */
MG_UECC_VLI_API cmpresult_t mg_uecc_vli_cmp(const mg_uecc_word_t *left,
                                            const mg_uecc_word_t *right,
                                            wordcount_t num_words) {
  mg_uecc_word_t tmp[MG_UECC_MAX_WORDS];
  mg_uecc_word_t neg = !!mg_uecc_vli_sub(tmp, left, right, num_words);
  mg_uecc_word_t equal = mg_uecc_vli_isZero(tmp, num_words);
  return (cmpresult_t) (!equal - 2 * neg);
}

/* Computes vli = vli >> 1. */
#if !asm_rshift1
MG_UECC_VLI_API void mg_uecc_vli_rshift1(mg_uecc_word_t *vli,
                                         wordcount_t num_words) {
  mg_uecc_word_t *end = vli;
  mg_uecc_word_t carry = 0;

  vli += num_words;
  while (vli-- > end) {
    mg_uecc_word_t temp = *vli;
    *vli = (temp >> 1) | carry;
    carry = temp << (MG_UECC_WORD_BITS - 1);
  }
}
#endif /* !asm_rshift1 */

/* Computes result = left + right, returning carry. Can modify in place. */
#if !asm_add
MG_UECC_VLI_API mg_uecc_word_t mg_uecc_vli_add(mg_uecc_word_t *result,
                                               const mg_uecc_word_t *left,
                                               const mg_uecc_word_t *right,
                                               wordcount_t num_words) {
  mg_uecc_word_t carry = 0;
  wordcount_t i;
  for (i = 0; i < num_words; ++i) {
    mg_uecc_word_t sum = left[i] + right[i] + carry;
    if (sum != left[i]) {
      carry = (sum < left[i]);
    }
    result[i] = sum;
  }
  return carry;
}
#endif /* !asm_add */

/* Computes result = left - right, returning borrow. Can modify in place. */
#if !asm_sub
MG_UECC_VLI_API mg_uecc_word_t mg_uecc_vli_sub(mg_uecc_word_t *result,
                                               const mg_uecc_word_t *left,
                                               const mg_uecc_word_t *right,
                                               wordcount_t num_words) {
  mg_uecc_word_t borrow = 0;
  wordcount_t i;
  for (i = 0; i < num_words; ++i) {
    mg_uecc_word_t diff = left[i] - right[i] - borrow;
    if (diff != left[i]) {
      borrow = (diff > left[i]);
    }
    result[i] = diff;
  }
  return borrow;
}
#endif /* !asm_sub */

#if !asm_mult || (MG_UECC_SQUARE_FUNC && !asm_square) ||               \
    (MG_UECC_SUPPORTS_secp256k1 && (MG_UECC_OPTIMIZATION_LEVEL > 0) && \
     ((MG_UECC_WORD_SIZE == 1) || (MG_UECC_WORD_SIZE == 8)))
static void muladd(mg_uecc_word_t a, mg_uecc_word_t b, mg_uecc_word_t *r0,
                   mg_uecc_word_t *r1, mg_uecc_word_t *r2) {
#if MG_UECC_WORD_SIZE == 8
  uint64_t a0 = a & 0xffffffff;
  uint64_t a1 = a >> 32;
  uint64_t b0 = b & 0xffffffff;
  uint64_t b1 = b >> 32;

  uint64_t i0 = a0 * b0;
  uint64_t i1 = a0 * b1;
  uint64_t i2 = a1 * b0;
  uint64_t i3 = a1 * b1;

  uint64_t p0, p1;

  i2 += (i0 >> 32);
  i2 += i1;
  if (i2 < i1) { /* overflow */
    i3 += 0x100000000;
  }

  p0 = (i0 & 0xffffffff) | (i2 << 32);
  p1 = i3 + (i2 >> 32);

  *r0 += p0;
  *r1 += (p1 + (*r0 < p0));
  *r2 += ((*r1 < p1) || (*r1 == p1 && *r0 < p0));
#else
  mg_uecc_dword_t p = (mg_uecc_dword_t) a * b;
  mg_uecc_dword_t r01 = ((mg_uecc_dword_t) (*r1) << MG_UECC_WORD_BITS) | *r0;
  r01 += p;
  *r2 += (r01 < p);
  *r1 = (mg_uecc_word_t) (r01 >> MG_UECC_WORD_BITS);
  *r0 = (mg_uecc_word_t) r01;
#endif
}
#endif /* muladd needed */

#if !asm_mult
MG_UECC_VLI_API void mg_uecc_vli_mult(mg_uecc_word_t *result,
                                      const mg_uecc_word_t *left,
                                      const mg_uecc_word_t *right,
                                      wordcount_t num_words) {
  mg_uecc_word_t r0 = 0;
  mg_uecc_word_t r1 = 0;
  mg_uecc_word_t r2 = 0;
  wordcount_t i, k;

  /* Compute each digit of result in sequence, maintaining the carries. */
  for (k = 0; k < num_words; ++k) {
    for (i = 0; i <= k; ++i) {
      muladd(left[i], right[k - i], &r0, &r1, &r2);
    }
    result[k] = r0;
    r0 = r1;
    r1 = r2;
    r2 = 0;
  }
  for (k = num_words; k < num_words * 2 - 1; ++k) {
    for (i = (wordcount_t) ((k + 1) - num_words); i < num_words; ++i) {
      muladd(left[i], right[k - i], &r0, &r1, &r2);
    }
    result[k] = r0;
    r0 = r1;
    r1 = r2;
    r2 = 0;
  }
  result[num_words * 2 - 1] = r0;
}
#endif /* !asm_mult */

#if MG_UECC_SQUARE_FUNC

#if !asm_square
static void mul2add(mg_uecc_word_t a, mg_uecc_word_t b, mg_uecc_word_t *r0,
                    mg_uecc_word_t *r1, mg_uecc_word_t *r2) {
#if MG_UECC_WORD_SIZE == 8
  uint64_t a0 = a & 0xffffffffull;
  uint64_t a1 = a >> 32;
  uint64_t b0 = b & 0xffffffffull;
  uint64_t b1 = b >> 32;

  uint64_t i0 = a0 * b0;
  uint64_t i1 = a0 * b1;
  uint64_t i2 = a1 * b0;
  uint64_t i3 = a1 * b1;

  uint64_t p0, p1;

  i2 += (i0 >> 32);
  i2 += i1;
  if (i2 < i1) { /* overflow */
    i3 += 0x100000000ull;
  }

  p0 = (i0 & 0xffffffffull) | (i2 << 32);
  p1 = i3 + (i2 >> 32);

  *r2 += (p1 >> 63);
  p1 = (p1 << 1) | (p0 >> 63);
  p0 <<= 1;

  *r0 += p0;
  *r1 += (p1 + (*r0 < p0));
  *r2 += ((*r1 < p1) || (*r1 == p1 && *r0 < p0));
#else
  mg_uecc_dword_t p = (mg_uecc_dword_t) a * b;
  mg_uecc_dword_t r01 = ((mg_uecc_dword_t) (*r1) << MG_UECC_WORD_BITS) | *r0;
  *r2 += (p >> (MG_UECC_WORD_BITS * 2 - 1));
  p *= 2;
  r01 += p;
  *r2 += (r01 < p);
  *r1 = r01 >> MG_UECC_WORD_BITS;
  *r0 = (mg_uecc_word_t) r01;
#endif
}

MG_UECC_VLI_API void mg_uecc_vli_square(mg_uecc_word_t *result,
                                        const mg_uecc_word_t *left,
                                        wordcount_t num_words) {
  mg_uecc_word_t r0 = 0;
  mg_uecc_word_t r1 = 0;
  mg_uecc_word_t r2 = 0;

  wordcount_t i, k;

  for (k = 0; k < num_words * 2 - 1; ++k) {
    mg_uecc_word_t min = (k < num_words ? 0 : (k + 1) - num_words);
    for (i = min; i <= k && i <= k - i; ++i) {
      if (i < k - i) {
        mul2add(left[i], left[k - i], &r0, &r1, &r2);
      } else {
        muladd(left[i], left[k - i], &r0, &r1, &r2);
      }
    }
    result[k] = r0;
    r0 = r1;
    r1 = r2;
    r2 = 0;
  }

  result[num_words * 2 - 1] = r0;
}
#endif /* !asm_square */

#else /* MG_UECC_SQUARE_FUNC */

#if MG_UECC_ENABLE_VLI_API
MG_UECC_VLI_API void mg_uecc_vli_square(mg_uecc_word_t *result,
                                        const mg_uecc_word_t *left,
                                        wordcount_t num_words) {
  mg_uecc_vli_mult(result, left, left, num_words);
}
#endif /* MG_UECC_ENABLE_VLI_API */

#endif /* MG_UECC_SQUARE_FUNC */

/* Computes result = (left + right) % mod.
   Assumes that left < mod and right < mod, and that result does not overlap
   mod. */
MG_UECC_VLI_API void mg_uecc_vli_modAdd(mg_uecc_word_t *result,
                                        const mg_uecc_word_t *left,
                                        const mg_uecc_word_t *right,
                                        const mg_uecc_word_t *mod,
                                        wordcount_t num_words) {
  mg_uecc_word_t carry = mg_uecc_vli_add(result, left, right, num_words);
  if (carry || mg_uecc_vli_cmp_unsafe(mod, result, num_words) != 1) {
    /* result > mod (result = mod + remainder), so subtract mod to get
     * remainder. */
    mg_uecc_vli_sub(result, result, mod, num_words);
  }
}

/* Computes result = (left - right) % mod.
   Assumes that left < mod and right < mod, and that result does not overlap
   mod. */
MG_UECC_VLI_API void mg_uecc_vli_modSub(mg_uecc_word_t *result,
                                        const mg_uecc_word_t *left,
                                        const mg_uecc_word_t *right,
                                        const mg_uecc_word_t *mod,
                                        wordcount_t num_words) {
  mg_uecc_word_t l_borrow = mg_uecc_vli_sub(result, left, right, num_words);
  if (l_borrow) {
    /* In this case, result == -diff == (max int) - diff. Since -x % d == d - x,
       we can get the correct result from result + mod (with overflow). */
    mg_uecc_vli_add(result, result, mod, num_words);
  }
}

/* Computes result = product % mod, where product is 2N words long. */
/* Currently only designed to work for curve_p or curve_n. */
MG_UECC_VLI_API void mg_uecc_vli_mmod(mg_uecc_word_t *result,
                                      mg_uecc_word_t *product,
                                      const mg_uecc_word_t *mod,
                                      wordcount_t num_words) {
  mg_uecc_word_t mod_multiple[2 * MG_UECC_MAX_WORDS];
  mg_uecc_word_t tmp[2 * MG_UECC_MAX_WORDS];
  mg_uecc_word_t *v[2] = {tmp, product};
  mg_uecc_word_t index;

  /* Shift mod so its highest set bit is at the maximum position. */
  bitcount_t shift = (bitcount_t) ((num_words * 2 * MG_UECC_WORD_BITS) -
                                   mg_uecc_vli_numBits(mod, num_words));
  wordcount_t word_shift = (wordcount_t) (shift / MG_UECC_WORD_BITS);
  wordcount_t bit_shift = (wordcount_t) (shift % MG_UECC_WORD_BITS);
  mg_uecc_word_t carry = 0;
  mg_uecc_vli_clear(mod_multiple, word_shift);
  if (bit_shift > 0) {
    for (index = 0; index < (mg_uecc_word_t) num_words; ++index) {
      mod_multiple[(mg_uecc_word_t) word_shift + index] =
          (mg_uecc_word_t) (mod[index] << bit_shift) | carry;
      carry = mod[index] >> (MG_UECC_WORD_BITS - bit_shift);
    }
  } else {
    mg_uecc_vli_set(mod_multiple + word_shift, mod, num_words);
  }

  for (index = 1; shift >= 0; --shift) {
    mg_uecc_word_t borrow = 0;
    wordcount_t i;
    for (i = 0; i < num_words * 2; ++i) {
      mg_uecc_word_t diff = v[index][i] - mod_multiple[i] - borrow;
      if (diff != v[index][i]) {
        borrow = (diff > v[index][i]);
      }
      v[1 - index][i] = diff;
    }
    index = !(index ^ borrow); /* Swap the index if there was no borrow */
    mg_uecc_vli_rshift1(mod_multiple, num_words);
    mod_multiple[num_words - 1] |= mod_multiple[num_words]
                                   << (MG_UECC_WORD_BITS - 1);
    mg_uecc_vli_rshift1(mod_multiple + num_words, num_words);
  }
  mg_uecc_vli_set(result, v[index], num_words);
}

/* Computes result = (left * right) % mod. */
MG_UECC_VLI_API void mg_uecc_vli_modMult(mg_uecc_word_t *result,
                                         const mg_uecc_word_t *left,
                                         const mg_uecc_word_t *right,
                                         const mg_uecc_word_t *mod,
                                         wordcount_t num_words) {
  mg_uecc_word_t product[2 * MG_UECC_MAX_WORDS];
  mg_uecc_vli_mult(product, left, right, num_words);
  mg_uecc_vli_mmod(result, product, mod, num_words);
}

MG_UECC_VLI_API void mg_uecc_vli_modMult_fast(mg_uecc_word_t *result,
                                              const mg_uecc_word_t *left,
                                              const mg_uecc_word_t *right,
                                              MG_UECC_Curve curve) {
  mg_uecc_word_t product[2 * MG_UECC_MAX_WORDS];
  mg_uecc_vli_mult(product, left, right, curve->num_words);
#if (MG_UECC_OPTIMIZATION_LEVEL > 0)
  curve->mmod_fast(result, product);
#else
  mg_uecc_vli_mmod(result, product, curve->p, curve->num_words);
#endif
}

#if MG_UECC_SQUARE_FUNC

#if MG_UECC_ENABLE_VLI_API
/* Computes result = left^2 % mod. */
MG_UECC_VLI_API void mg_uecc_vli_modSquare(mg_uecc_word_t *result,
                                           const mg_uecc_word_t *left,
                                           const mg_uecc_word_t *mod,
                                           wordcount_t num_words) {
  mg_uecc_word_t product[2 * MG_UECC_MAX_WORDS];
  mg_uecc_vli_square(product, left, num_words);
  mg_uecc_vli_mmod(result, product, mod, num_words);
}
#endif /* MG_UECC_ENABLE_VLI_API */

MG_UECC_VLI_API void mg_uecc_vli_modSquare_fast(mg_uecc_word_t *result,
                                                const mg_uecc_word_t *left,
                                                MG_UECC_Curve curve) {
  mg_uecc_word_t product[2 * MG_UECC_MAX_WORDS];
  mg_uecc_vli_square(product, left, curve->num_words);
#if (MG_UECC_OPTIMIZATION_LEVEL > 0)
  curve->mmod_fast(result, product);
#else
  mg_uecc_vli_mmod(result, product, curve->p, curve->num_words);
#endif
}

#else /* MG_UECC_SQUARE_FUNC */

#if MG_UECC_ENABLE_VLI_API
MG_UECC_VLI_API void mg_uecc_vli_modSquare(mg_uecc_word_t *result,
                                           const mg_uecc_word_t *left,
                                           const mg_uecc_word_t *mod,
                                           wordcount_t num_words) {
  mg_uecc_vli_modMult(result, left, left, mod, num_words);
}
#endif /* MG_UECC_ENABLE_VLI_API */

MG_UECC_VLI_API void mg_uecc_vli_modSquare_fast(mg_uecc_word_t *result,
                                                const mg_uecc_word_t *left,
                                                MG_UECC_Curve curve) {
  mg_uecc_vli_modMult_fast(result, left, left, curve);
}

#endif /* MG_UECC_SQUARE_FUNC */

#define EVEN(vli) (!(vli[0] & 1))
static void vli_modInv_update(mg_uecc_word_t *uv, const mg_uecc_word_t *mod,
                              wordcount_t num_words) {
  mg_uecc_word_t carry = 0;
  if (!EVEN(uv)) {
    carry = mg_uecc_vli_add(uv, uv, mod, num_words);
  }
  mg_uecc_vli_rshift1(uv, num_words);
  if (carry) {
    uv[num_words - 1] |= HIGH_BIT_SET;
  }
}

/* Computes result = (1 / input) % mod. All VLIs are the same size.
   See "From Euclid's GCD to Montgomery Multiplication to the Great Divide" */
MG_UECC_VLI_API void mg_uecc_vli_modInv(mg_uecc_word_t *result,
                                        const mg_uecc_word_t *input,
                                        const mg_uecc_word_t *mod,
                                        wordcount_t num_words) {
  mg_uecc_word_t a[MG_UECC_MAX_WORDS], b[MG_UECC_MAX_WORDS],
      u[MG_UECC_MAX_WORDS], v[MG_UECC_MAX_WORDS];
  cmpresult_t cmpResult;

  if (mg_uecc_vli_isZero(input, num_words)) {
    mg_uecc_vli_clear(result, num_words);
    return;
  }

  mg_uecc_vli_set(a, input, num_words);
  mg_uecc_vli_set(b, mod, num_words);
  mg_uecc_vli_clear(u, num_words);
  u[0] = 1;
  mg_uecc_vli_clear(v, num_words);
  while ((cmpResult = mg_uecc_vli_cmp_unsafe(a, b, num_words)) != 0) {
    if (EVEN(a)) {
      mg_uecc_vli_rshift1(a, num_words);
      vli_modInv_update(u, mod, num_words);
    } else if (EVEN(b)) {
      mg_uecc_vli_rshift1(b, num_words);
      vli_modInv_update(v, mod, num_words);
    } else if (cmpResult > 0) {
      mg_uecc_vli_sub(a, a, b, num_words);
      mg_uecc_vli_rshift1(a, num_words);
      if (mg_uecc_vli_cmp_unsafe(u, v, num_words) < 0) {
        mg_uecc_vli_add(u, u, mod, num_words);
      }
      mg_uecc_vli_sub(u, u, v, num_words);
      vli_modInv_update(u, mod, num_words);
    } else {
      mg_uecc_vli_sub(b, b, a, num_words);
      mg_uecc_vli_rshift1(b, num_words);
      if (mg_uecc_vli_cmp_unsafe(v, u, num_words) < 0) {
        mg_uecc_vli_add(v, v, mod, num_words);
      }
      mg_uecc_vli_sub(v, v, u, num_words);
      vli_modInv_update(v, mod, num_words);
    }
  }
  mg_uecc_vli_set(result, u, num_words);
}

/* ------ Point operations ------ */

/* Copyright 2015, Kenneth MacKay. Licensed under the BSD 2-clause license. */

#ifndef _UECC_CURVE_SPECIFIC_H_
#define _UECC_CURVE_SPECIFIC_H_

#define num_bytes_secp160r1 20
#define num_bytes_secp192r1 24
#define num_bytes_secp224r1 28
#define num_bytes_secp256r1 32
#define num_bytes_secp256k1 32

#if (MG_UECC_WORD_SIZE == 1)

#define num_words_secp160r1 20
#define num_words_secp192r1 24
#define num_words_secp224r1 28
#define num_words_secp256r1 32
#define num_words_secp256k1 32

#define BYTES_TO_WORDS_8(a, b, c, d, e, f, g, h) \
  0x##a, 0x##b, 0x##c, 0x##d, 0x##e, 0x##f, 0x##g, 0x##h
#define BYTES_TO_WORDS_4(a, b, c, d) 0x##a, 0x##b, 0x##c, 0x##d

#elif (MG_UECC_WORD_SIZE == 4)

#define num_words_secp160r1 5
#define num_words_secp192r1 6
#define num_words_secp224r1 7
#define num_words_secp256r1 8
#define num_words_secp256k1 8

#define BYTES_TO_WORDS_8(a, b, c, d, e, f, g, h) 0x##d##c##b##a, 0x##h##g##f##e
#define BYTES_TO_WORDS_4(a, b, c, d) 0x##d##c##b##a

#elif (MG_UECC_WORD_SIZE == 8)

#define num_words_secp160r1 3
#define num_words_secp192r1 3
#define num_words_secp224r1 4
#define num_words_secp256r1 4
#define num_words_secp256k1 4

#define BYTES_TO_WORDS_8(a, b, c, d, e, f, g, h) 0x##h##g##f##e##d##c##b##a##U
#define BYTES_TO_WORDS_4(a, b, c, d) 0x##d##c##b##a##U

#endif /* MG_UECC_WORD_SIZE */

#if MG_UECC_SUPPORTS_secp160r1 || MG_UECC_SUPPORTS_secp192r1 || \
    MG_UECC_SUPPORTS_secp224r1 || MG_UECC_SUPPORTS_secp256r1
static void double_jacobian_default(mg_uecc_word_t *X1, mg_uecc_word_t *Y1,
                                    mg_uecc_word_t *Z1, MG_UECC_Curve curve) {
  /* t1 = X, t2 = Y, t3 = Z */
  mg_uecc_word_t t4[MG_UECC_MAX_WORDS];
  mg_uecc_word_t t5[MG_UECC_MAX_WORDS];
  wordcount_t num_words = curve->num_words;

  if (mg_uecc_vli_isZero(Z1, num_words)) {
    return;
  }

  mg_uecc_vli_modSquare_fast(t4, Y1, curve);   /* t4 = y1^2 */
  mg_uecc_vli_modMult_fast(t5, X1, t4, curve); /* t5 = x1*y1^2 = A */
  mg_uecc_vli_modSquare_fast(t4, t4, curve);   /* t4 = y1^4 */
  mg_uecc_vli_modMult_fast(Y1, Y1, Z1, curve); /* t2 = y1*z1 = z3 */
  mg_uecc_vli_modSquare_fast(Z1, Z1, curve);   /* t3 = z1^2 */

  mg_uecc_vli_modAdd(X1, X1, Z1, curve->p, num_words); /* t1 = x1 + z1^2 */
  mg_uecc_vli_modAdd(Z1, Z1, Z1, curve->p, num_words); /* t3 = 2*z1^2 */
  mg_uecc_vli_modSub(Z1, X1, Z1, curve->p, num_words); /* t3 = x1 - z1^2 */
  mg_uecc_vli_modMult_fast(X1, X1, Z1, curve);         /* t1 = x1^2 - z1^4 */

  mg_uecc_vli_modAdd(Z1, X1, X1, curve->p,
                     num_words); /* t3 = 2*(x1^2 - z1^4) */
  mg_uecc_vli_modAdd(X1, X1, Z1, curve->p,
                     num_words); /* t1 = 3*(x1^2 - z1^4) */
  if (mg_uecc_vli_testBit(X1, 0)) {
    mg_uecc_word_t l_carry = mg_uecc_vli_add(X1, X1, curve->p, num_words);
    mg_uecc_vli_rshift1(X1, num_words);
    X1[num_words - 1] |= l_carry << (MG_UECC_WORD_BITS - 1);
  } else {
    mg_uecc_vli_rshift1(X1, num_words);
  }
  /* t1 = 3/2*(x1^2 - z1^4) = B */

  mg_uecc_vli_modSquare_fast(Z1, X1, curve);           /* t3 = B^2 */
  mg_uecc_vli_modSub(Z1, Z1, t5, curve->p, num_words); /* t3 = B^2 - A */
  mg_uecc_vli_modSub(Z1, Z1, t5, curve->p, num_words); /* t3 = B^2 - 2A = x3 */
  mg_uecc_vli_modSub(t5, t5, Z1, curve->p, num_words); /* t5 = A - x3 */
  mg_uecc_vli_modMult_fast(X1, X1, t5, curve);         /* t1 = B * (A - x3) */
  mg_uecc_vli_modSub(t4, X1, t4, curve->p,
                     num_words); /* t4 = B * (A - x3) - y1^4 = y3 */

  mg_uecc_vli_set(X1, Z1, num_words);
  mg_uecc_vli_set(Z1, Y1, num_words);
  mg_uecc_vli_set(Y1, t4, num_words);
}

/* Computes result = x^3 + ax + b. result must not overlap x. */
static void x_side_default(mg_uecc_word_t *result, const mg_uecc_word_t *x,
                           MG_UECC_Curve curve) {
  mg_uecc_word_t _3[MG_UECC_MAX_WORDS] = {3}; /* -a = 3 */
  wordcount_t num_words = curve->num_words;

  mg_uecc_vli_modSquare_fast(result, x, curve);                /* r = x^2 */
  mg_uecc_vli_modSub(result, result, _3, curve->p, num_words); /* r = x^2 - 3 */
  mg_uecc_vli_modMult_fast(result, result, x, curve); /* r = x^3 - 3x */
  mg_uecc_vli_modAdd(result, result, curve->b, curve->p,
                     num_words); /* r = x^3 - 3x + b */
}
#endif /* MG_UECC_SUPPORTS_secp... */

#if MG_UECC_SUPPORT_COMPRESSED_POINT
#if MG_UECC_SUPPORTS_secp160r1 || MG_UECC_SUPPORTS_secp192r1 || \
    MG_UECC_SUPPORTS_secp256r1 || MG_UECC_SUPPORTS_secp256k1
/* Compute a = sqrt(a) (mod curve_p). */
static void mod_sqrt_default(mg_uecc_word_t *a, MG_UECC_Curve curve) {
  bitcount_t i;
  mg_uecc_word_t p1[MG_UECC_MAX_WORDS] = {1};
  mg_uecc_word_t l_result[MG_UECC_MAX_WORDS] = {1};
  wordcount_t num_words = curve->num_words;

  /* When curve->p == 3 (mod 4), we can compute
     sqrt(a) = a^((curve->p + 1) / 4) (mod curve->p). */
  mg_uecc_vli_add(p1, curve->p, p1, num_words); /* p1 = curve_p + 1 */
  for (i = mg_uecc_vli_numBits(p1, num_words) - 1; i > 1; --i) {
    mg_uecc_vli_modSquare_fast(l_result, l_result, curve);
    if (mg_uecc_vli_testBit(p1, i)) {
      mg_uecc_vli_modMult_fast(l_result, l_result, a, curve);
    }
  }
  mg_uecc_vli_set(a, l_result, num_words);
}
#endif /* MG_UECC_SUPPORTS_secp... */
#endif /* MG_UECC_SUPPORT_COMPRESSED_POINT */

#if MG_UECC_SUPPORTS_secp160r1

#if (MG_UECC_OPTIMIZATION_LEVEL > 0)
static void vli_mmod_fast_secp160r1(mg_uecc_word_t *result,
                                    mg_uecc_word_t *product);
#endif

static const struct MG_UECC_Curve_t curve_secp160r1 = {
    num_words_secp160r1,
    num_bytes_secp160r1,
    161, /* num_n_bits */
    {BYTES_TO_WORDS_8(FF, FF, FF, 7F, FF, FF, FF, FF),
     BYTES_TO_WORDS_8(FF, FF, FF, FF, FF, FF, FF, FF),
     BYTES_TO_WORDS_4(FF, FF, FF, FF)},
    {BYTES_TO_WORDS_8(57, 22, 75, CA, D3, AE, 27, F9),
     BYTES_TO_WORDS_8(C8, F4, 01, 00, 00, 00, 00, 00),
     BYTES_TO_WORDS_8(00, 00, 00, 00, 01, 00, 00, 00)},
    {BYTES_TO_WORDS_8(82, FC, CB, 13, B9, 8B, C3, 68),
     BYTES_TO_WORDS_8(89, 69, 64, 46, 28, 73, F5, 8E),
     BYTES_TO_WORDS_4(68, B5, 96, 4A),

     BYTES_TO_WORDS_8(32, FB, C5, 7A, 37, 51, 23, 04),
     BYTES_TO_WORDS_8(12, C9, DC, 59, 7D, 94, 68, 31),
     BYTES_TO_WORDS_4(55, 28, A6, 23)},
    {BYTES_TO_WORDS_8(45, FA, 65, C5, AD, D4, D4, 81),
     BYTES_TO_WORDS_8(9F, F8, AC, 65, 8B, 7A, BD, 54),
     BYTES_TO_WORDS_4(FC, BE, 97, 1C)},
    &double_jacobian_default,
#if MG_UECC_SUPPORT_COMPRESSED_POINT
    &mod_sqrt_default,
#endif
    &x_side_default,
#if (MG_UECC_OPTIMIZATION_LEVEL > 0)
    &vli_mmod_fast_secp160r1
#endif
};

MG_UECC_Curve mg_uecc_secp160r1(void) {
  return &curve_secp160r1;
}

#if (MG_UECC_OPTIMIZATION_LEVEL > 0 && !asm_mmod_fast_secp160r1)
/* Computes result = product % curve_p
    see http://www.isys.uni-klu.ac.at/PDF/2001-0126-MT.pdf page 354

    Note that this only works if log2(omega) < log2(p) / 2 */
static void omega_mult_secp160r1(mg_uecc_word_t *result,
                                 const mg_uecc_word_t *right);
#if MG_UECC_WORD_SIZE == 8
static void vli_mmod_fast_secp160r1(mg_uecc_word_t *result,
                                    mg_uecc_word_t *product) {
  mg_uecc_word_t tmp[2 * num_words_secp160r1];
  mg_uecc_word_t copy;

  mg_uecc_vli_clear(tmp, num_words_secp160r1);
  mg_uecc_vli_clear(tmp + num_words_secp160r1, num_words_secp160r1);

  omega_mult_secp160r1(tmp,
                       product + num_words_secp160r1 - 1); /* (Rq, q) = q * c */

  product[num_words_secp160r1 - 1] &= 0xffffffff;
  copy = tmp[num_words_secp160r1 - 1];
  tmp[num_words_secp160r1 - 1] &= 0xffffffff;
  mg_uecc_vli_add(result, product, tmp,
                  num_words_secp160r1); /* (C, r) = r + q */
  mg_uecc_vli_clear(product, num_words_secp160r1);
  tmp[num_words_secp160r1 - 1] = copy;
  omega_mult_secp160r1(product, tmp + num_words_secp160r1 - 1); /* Rq*c */
  mg_uecc_vli_add(result, result, product,
                  num_words_secp160r1); /* (C1, r) = r + Rq*c */

  while (mg_uecc_vli_cmp_unsafe(result, curve_secp160r1.p,
                                num_words_secp160r1) > 0) {
    mg_uecc_vli_sub(result, result, curve_secp160r1.p, num_words_secp160r1);
  }
}

static void omega_mult_secp160r1(uint64_t *result, const uint64_t *right) {
  uint32_t carry;
  unsigned i;

  /* Multiply by (2^31 + 1). */
  carry = 0;
  for (i = 0; i < num_words_secp160r1; ++i) {
    uint64_t tmp = (right[i] >> 32) | (right[i + 1] << 32);
    result[i] = (tmp << 31) + tmp + carry;
    carry = (tmp >> 33) + (result[i] < tmp || (carry && result[i] == tmp));
  }
  result[i] = carry;
}
#else
static void vli_mmod_fast_secp160r1(mg_uecc_word_t *result,
                                    mg_uecc_word_t *product) {
  mg_uecc_word_t tmp[2 * num_words_secp160r1];
  mg_uecc_word_t carry;

  mg_uecc_vli_clear(tmp, num_words_secp160r1);
  mg_uecc_vli_clear(tmp + num_words_secp160r1, num_words_secp160r1);

  omega_mult_secp160r1(tmp,
                       product + num_words_secp160r1); /* (Rq, q) = q * c */

  carry = mg_uecc_vli_add(result, product, tmp,
                          num_words_secp160r1); /* (C, r) = r + q */
  mg_uecc_vli_clear(product, num_words_secp160r1);
  omega_mult_secp160r1(product, tmp + num_words_secp160r1); /* Rq*c */
  carry += mg_uecc_vli_add(result, result, product,
                           num_words_secp160r1); /* (C1, r) = r + Rq*c */

  while (carry > 0) {
    --carry;
    mg_uecc_vli_sub(result, result, curve_secp160r1.p, num_words_secp160r1);
  }
  if (mg_uecc_vli_cmp_unsafe(result, curve_secp160r1.p, num_words_secp160r1) >
      0) {
    mg_uecc_vli_sub(result, result, curve_secp160r1.p, num_words_secp160r1);
  }
}
#endif

#if MG_UECC_WORD_SIZE == 1
static void omega_mult_secp160r1(uint8_t *result, const uint8_t *right) {
  uint8_t carry;
  uint8_t i;

  /* Multiply by (2^31 + 1). */
  mg_uecc_vli_set(result + 4, right, num_words_secp160r1); /* 2^32 */
  mg_uecc_vli_rshift1(result + 4, num_words_secp160r1);    /* 2^31 */
  result[3] = right[0] << 7; /* get last bit from shift */

  carry = mg_uecc_vli_add(result, result, right,
                          num_words_secp160r1); /* 2^31 + 1 */
  for (i = num_words_secp160r1; carry; ++i) {
    uint16_t sum = (uint16_t) result[i] + carry;
    result[i] = (uint8_t) sum;
    carry = sum >> 8;
  }
}
#elif MG_UECC_WORD_SIZE == 4
static void omega_mult_secp160r1(uint32_t *result, const uint32_t *right) {
  uint32_t carry;
  unsigned i;

  /* Multiply by (2^31 + 1). */
  mg_uecc_vli_set(result + 1, right, num_words_secp160r1); /* 2^32 */
  mg_uecc_vli_rshift1(result + 1, num_words_secp160r1);    /* 2^31 */
  result[0] = right[0] << 31; /* get last bit from shift */

  carry = mg_uecc_vli_add(result, result, right,
                          num_words_secp160r1); /* 2^31 + 1 */
  for (i = num_words_secp160r1; carry; ++i) {
    uint64_t sum = (uint64_t) result[i] + carry;
    result[i] = (uint32_t) sum;
    carry = sum >> 32;
  }
}
#endif /* MG_UECC_WORD_SIZE */
#endif /* (MG_UECC_OPTIMIZATION_LEVEL > 0 && !asm_mmod_fast_secp160r1) */

#endif /* MG_UECC_SUPPORTS_secp160r1 */

#if MG_UECC_SUPPORTS_secp192r1

#if (MG_UECC_OPTIMIZATION_LEVEL > 0)
static void vli_mmod_fast_secp192r1(mg_uecc_word_t *result,
                                    mg_uecc_word_t *product);
#endif

static const struct MG_UECC_Curve_t curve_secp192r1 = {
    num_words_secp192r1,
    num_bytes_secp192r1,
    192, /* num_n_bits */
    {BYTES_TO_WORDS_8(FF, FF, FF, FF, FF, FF, FF, FF),
     BYTES_TO_WORDS_8(FE, FF, FF, FF, FF, FF, FF, FF),
     BYTES_TO_WORDS_8(FF, FF, FF, FF, FF, FF, FF, FF)},
    {BYTES_TO_WORDS_8(31, 28, D2, B4, B1, C9, 6B, 14),
     BYTES_TO_WORDS_8(36, F8, DE, 99, FF, FF, FF, FF),
     BYTES_TO_WORDS_8(FF, FF, FF, FF, FF, FF, FF, FF)},
    {BYTES_TO_WORDS_8(12, 10, FF, 82, FD, 0A, FF, F4),
     BYTES_TO_WORDS_8(00, 88, A1, 43, EB, 20, BF, 7C),
     BYTES_TO_WORDS_8(F6, 90, 30, B0, 0E, A8, 8D, 18),

     BYTES_TO_WORDS_8(11, 48, 79, 1E, A1, 77, F9, 73),
     BYTES_TO_WORDS_8(D5, CD, 24, 6B, ED, 11, 10, 63),
     BYTES_TO_WORDS_8(78, DA, C8, FF, 95, 2B, 19, 07)},
    {BYTES_TO_WORDS_8(B1, B9, 46, C1, EC, DE, B8, FE),
     BYTES_TO_WORDS_8(49, 30, 24, 72, AB, E9, A7, 0F),
     BYTES_TO_WORDS_8(E7, 80, 9C, E5, 19, 05, 21, 64)},
    &double_jacobian_default,
#if MG_UECC_SUPPORT_COMPRESSED_POINT
    &mod_sqrt_default,
#endif
    &x_side_default,
#if (MG_UECC_OPTIMIZATION_LEVEL > 0)
    &vli_mmod_fast_secp192r1
#endif
};

MG_UECC_Curve mg_uecc_secp192r1(void) {
  return &curve_secp192r1;
}

#if (MG_UECC_OPTIMIZATION_LEVEL > 0)
/* Computes result = product % curve_p.
   See algorithm 5 and 6 from http://www.isys.uni-klu.ac.at/PDF/2001-0126-MT.pdf
 */
#if MG_UECC_WORD_SIZE == 1
static void vli_mmod_fast_secp192r1(uint8_t *result, uint8_t *product) {
  uint8_t tmp[num_words_secp192r1];
  uint8_t carry;

  mg_uecc_vli_set(result, product, num_words_secp192r1);

  mg_uecc_vli_set(tmp, &product[24], num_words_secp192r1);
  carry = mg_uecc_vli_add(result, result, tmp, num_words_secp192r1);

  tmp[0] = tmp[1] = tmp[2] = tmp[3] = tmp[4] = tmp[5] = tmp[6] = tmp[7] = 0;
  tmp[8] = product[24];
  tmp[9] = product[25];
  tmp[10] = product[26];
  tmp[11] = product[27];
  tmp[12] = product[28];
  tmp[13] = product[29];
  tmp[14] = product[30];
  tmp[15] = product[31];
  tmp[16] = product[32];
  tmp[17] = product[33];
  tmp[18] = product[34];
  tmp[19] = product[35];
  tmp[20] = product[36];
  tmp[21] = product[37];
  tmp[22] = product[38];
  tmp[23] = product[39];
  carry += mg_uecc_vli_add(result, result, tmp, num_words_secp192r1);

  tmp[0] = tmp[8] = product[40];
  tmp[1] = tmp[9] = product[41];
  tmp[2] = tmp[10] = product[42];
  tmp[3] = tmp[11] = product[43];
  tmp[4] = tmp[12] = product[44];
  tmp[5] = tmp[13] = product[45];
  tmp[6] = tmp[14] = product[46];
  tmp[7] = tmp[15] = product[47];
  tmp[16] = tmp[17] = tmp[18] = tmp[19] = tmp[20] = tmp[21] = tmp[22] =
      tmp[23] = 0;
  carry += mg_uecc_vli_add(result, result, tmp, num_words_secp192r1);

  while (carry || mg_uecc_vli_cmp_unsafe(curve_secp192r1.p, result,
                                         num_words_secp192r1) != 1) {
    carry -=
        mg_uecc_vli_sub(result, result, curve_secp192r1.p, num_words_secp192r1);
  }
}
#elif MG_UECC_WORD_SIZE == 4
static void vli_mmod_fast_secp192r1(uint32_t *result, uint32_t *product) {
  uint32_t tmp[num_words_secp192r1];
  int carry;

  mg_uecc_vli_set(result, product, num_words_secp192r1);

  mg_uecc_vli_set(tmp, &product[6], num_words_secp192r1);
  carry = mg_uecc_vli_add(result, result, tmp, num_words_secp192r1);

  tmp[0] = tmp[1] = 0;
  tmp[2] = product[6];
  tmp[3] = product[7];
  tmp[4] = product[8];
  tmp[5] = product[9];
  carry += mg_uecc_vli_add(result, result, tmp, num_words_secp192r1);

  tmp[0] = tmp[2] = product[10];
  tmp[1] = tmp[3] = product[11];
  tmp[4] = tmp[5] = 0;
  carry += mg_uecc_vli_add(result, result, tmp, num_words_secp192r1);

  while (carry || mg_uecc_vli_cmp_unsafe(curve_secp192r1.p, result,
                                         num_words_secp192r1) != 1) {
    carry -=
        mg_uecc_vli_sub(result, result, curve_secp192r1.p, num_words_secp192r1);
  }
}
#else
static void vli_mmod_fast_secp192r1(uint64_t *result, uint64_t *product) {
  uint64_t tmp[num_words_secp192r1];
  int carry;

  mg_uecc_vli_set(result, product, num_words_secp192r1);

  mg_uecc_vli_set(tmp, &product[3], num_words_secp192r1);
  carry = (int) mg_uecc_vli_add(result, result, tmp, num_words_secp192r1);

  tmp[0] = 0;
  tmp[1] = product[3];
  tmp[2] = product[4];
  carry += mg_uecc_vli_add(result, result, tmp, num_words_secp192r1);

  tmp[0] = tmp[1] = product[5];
  tmp[2] = 0;
  carry += mg_uecc_vli_add(result, result, tmp, num_words_secp192r1);

  while (carry || mg_uecc_vli_cmp_unsafe(curve_secp192r1.p, result,
                                         num_words_secp192r1) != 1) {
    carry -=
        mg_uecc_vli_sub(result, result, curve_secp192r1.p, num_words_secp192r1);
  }
}
#endif /* MG_UECC_WORD_SIZE */
#endif /* (MG_UECC_OPTIMIZATION_LEVEL > 0) */

#endif /* MG_UECC_SUPPORTS_secp192r1 */

#if MG_UECC_SUPPORTS_secp224r1

#if MG_UECC_SUPPORT_COMPRESSED_POINT
static void mod_sqrt_secp224r1(mg_uecc_word_t *a, MG_UECC_Curve curve);
#endif
#if (MG_UECC_OPTIMIZATION_LEVEL > 0)
static void vli_mmod_fast_secp224r1(mg_uecc_word_t *result,
                                    mg_uecc_word_t *product);
#endif

static const struct MG_UECC_Curve_t curve_secp224r1 = {
    num_words_secp224r1,
    num_bytes_secp224r1,
    224, /* num_n_bits */
    {BYTES_TO_WORDS_8(01, 00, 00, 00, 00, 00, 00, 00),
     BYTES_TO_WORDS_8(00, 00, 00, 00, FF, FF, FF, FF),
     BYTES_TO_WORDS_8(FF, FF, FF, FF, FF, FF, FF, FF),
     BYTES_TO_WORDS_4(FF, FF, FF, FF)},
    {BYTES_TO_WORDS_8(3D, 2A, 5C, 5C, 45, 29, DD, 13),
     BYTES_TO_WORDS_8(3E, F0, B8, E0, A2, 16, FF, FF),
     BYTES_TO_WORDS_8(FF, FF, FF, FF, FF, FF, FF, FF),
     BYTES_TO_WORDS_4(FF, FF, FF, FF)},
    {BYTES_TO_WORDS_8(21, 1D, 5C, 11, D6, 80, 32, 34),
     BYTES_TO_WORDS_8(22, 11, C2, 56, D3, C1, 03, 4A),
     BYTES_TO_WORDS_8(B9, 90, 13, 32, 7F, BF, B4, 6B),
     BYTES_TO_WORDS_4(BD, 0C, 0E, B7),

     BYTES_TO_WORDS_8(34, 7E, 00, 85, 99, 81, D5, 44),
     BYTES_TO_WORDS_8(64, 47, 07, 5A, A0, 75, 43, CD),
     BYTES_TO_WORDS_8(E6, DF, 22, 4C, FB, 23, F7, B5),
     BYTES_TO_WORDS_4(88, 63, 37, BD)},
    {BYTES_TO_WORDS_8(B4, FF, 55, 23, 43, 39, 0B, 27),
     BYTES_TO_WORDS_8(BA, D8, BF, D7, B7, B0, 44, 50),
     BYTES_TO_WORDS_8(56, 32, 41, F5, AB, B3, 04, 0C),
     BYTES_TO_WORDS_4(85, 0A, 05, B4)},
    &double_jacobian_default,
#if MG_UECC_SUPPORT_COMPRESSED_POINT
    &mod_sqrt_secp224r1,
#endif
    &x_side_default,
#if (MG_UECC_OPTIMIZATION_LEVEL > 0)
    &vli_mmod_fast_secp224r1
#endif
};

MG_UECC_Curve mg_uecc_secp224r1(void) {
  return &curve_secp224r1;
}

#if MG_UECC_SUPPORT_COMPRESSED_POINT
/* Routine 3.2.4 RS;  from http://www.nsa.gov/ia/_files/nist-routines.pdf */
static void mod_sqrt_secp224r1_rs(mg_uecc_word_t *d1, mg_uecc_word_t *e1,
                                  mg_uecc_word_t *f1, const mg_uecc_word_t *d0,
                                  const mg_uecc_word_t *e0,
                                  const mg_uecc_word_t *f0) {
  mg_uecc_word_t t[num_words_secp224r1];

  mg_uecc_vli_modSquare_fast(t, d0, &curve_secp224r1);    /* t <-- d0 ^ 2 */
  mg_uecc_vli_modMult_fast(e1, d0, e0, &curve_secp224r1); /* e1 <-- d0 * e0 */
  mg_uecc_vli_modAdd(d1, t, f0, curve_secp224r1.p,
                     num_words_secp224r1); /* d1 <-- t  + f0 */
  mg_uecc_vli_modAdd(e1, e1, e1, curve_secp224r1.p,
                     num_words_secp224r1);               /* e1 <-- e1 + e1 */
  mg_uecc_vli_modMult_fast(f1, t, f0, &curve_secp224r1); /* f1 <-- t  * f0 */
  mg_uecc_vli_modAdd(f1, f1, f1, curve_secp224r1.p,
                     num_words_secp224r1); /* f1 <-- f1 + f1 */
  mg_uecc_vli_modAdd(f1, f1, f1, curve_secp224r1.p,
                     num_words_secp224r1); /* f1 <-- f1 + f1 */
}

/* Routine 3.2.5 RSS;  from http://www.nsa.gov/ia/_files/nist-routines.pdf */
static void mod_sqrt_secp224r1_rss(mg_uecc_word_t *d1, mg_uecc_word_t *e1,
                                   mg_uecc_word_t *f1, const mg_uecc_word_t *d0,
                                   const mg_uecc_word_t *e0,
                                   const mg_uecc_word_t *f0,
                                   const bitcount_t j) {
  bitcount_t i;

  mg_uecc_vli_set(d1, d0, num_words_secp224r1); /* d1 <-- d0 */
  mg_uecc_vli_set(e1, e0, num_words_secp224r1); /* e1 <-- e0 */
  mg_uecc_vli_set(f1, f0, num_words_secp224r1); /* f1 <-- f0 */
  for (i = 1; i <= j; i++) {
    mod_sqrt_secp224r1_rs(d1, e1, f1, d1, e1, f1); /* RS (d1,e1,f1,d1,e1,f1) */
  }
}

/* Routine 3.2.6 RM;  from http://www.nsa.gov/ia/_files/nist-routines.pdf */
static void mod_sqrt_secp224r1_rm(mg_uecc_word_t *d2, mg_uecc_word_t *e2,
                                  mg_uecc_word_t *f2, const mg_uecc_word_t *c,
                                  const mg_uecc_word_t *d0,
                                  const mg_uecc_word_t *e0,
                                  const mg_uecc_word_t *d1,
                                  const mg_uecc_word_t *e1) {
  mg_uecc_word_t t1[num_words_secp224r1];
  mg_uecc_word_t t2[num_words_secp224r1];

  mg_uecc_vli_modMult_fast(t1, e0, e1, &curve_secp224r1); /* t1 <-- e0 * e1 */
  mg_uecc_vli_modMult_fast(t1, t1, c, &curve_secp224r1);  /* t1 <-- t1 * c */
  /* t1 <-- p  - t1 */
  mg_uecc_vli_modSub(t1, curve_secp224r1.p, t1, curve_secp224r1.p,
                     num_words_secp224r1);
  mg_uecc_vli_modMult_fast(t2, d0, d1, &curve_secp224r1); /* t2 <-- d0 * d1 */
  mg_uecc_vli_modAdd(t2, t2, t1, curve_secp224r1.p,
                     num_words_secp224r1);                /* t2 <-- t2 + t1 */
  mg_uecc_vli_modMult_fast(t1, d0, e1, &curve_secp224r1); /* t1 <-- d0 * e1 */
  mg_uecc_vli_modMult_fast(e2, d1, e0, &curve_secp224r1); /* e2 <-- d1 * e0 */
  mg_uecc_vli_modAdd(e2, e2, t1, curve_secp224r1.p,
                     num_words_secp224r1);               /* e2 <-- e2 + t1 */
  mg_uecc_vli_modSquare_fast(f2, e2, &curve_secp224r1);  /* f2 <-- e2^2 */
  mg_uecc_vli_modMult_fast(f2, f2, c, &curve_secp224r1); /* f2 <-- f2 * c */
  /* f2 <-- p  - f2 */
  mg_uecc_vli_modSub(f2, curve_secp224r1.p, f2, curve_secp224r1.p,
                     num_words_secp224r1);
  mg_uecc_vli_set(d2, t2, num_words_secp224r1); /* d2 <-- t2 */
}

/* Routine 3.2.7 RP;  from http://www.nsa.gov/ia/_files/nist-routines.pdf */
static void mod_sqrt_secp224r1_rp(mg_uecc_word_t *d1, mg_uecc_word_t *e1,
                                  mg_uecc_word_t *f1, const mg_uecc_word_t *c,
                                  const mg_uecc_word_t *r) {
  wordcount_t i;
  wordcount_t pow2i = 1;
  mg_uecc_word_t d0[num_words_secp224r1];
  mg_uecc_word_t e0[num_words_secp224r1] = {1}; /* e0 <-- 1 */
  mg_uecc_word_t f0[num_words_secp224r1];

  mg_uecc_vli_set(d0, r, num_words_secp224r1); /* d0 <-- r */
  /* f0 <-- p  - c */
  mg_uecc_vli_modSub(f0, curve_secp224r1.p, c, curve_secp224r1.p,
                     num_words_secp224r1);
  for (i = 0; i <= 6; i++) {
    mod_sqrt_secp224r1_rss(d1, e1, f1, d0, e0, f0,
                           pow2i); /* RSS (d1,e1,f1,d0,e0,f0,2^i) */
    mod_sqrt_secp224r1_rm(d1, e1, f1, c, d1, e1, d0,
                          e0); /* RM (d1,e1,f1,c,d1,e1,d0,e0) */
    mg_uecc_vli_set(d0, d1, num_words_secp224r1); /* d0 <-- d1 */
    mg_uecc_vli_set(e0, e1, num_words_secp224r1); /* e0 <-- e1 */
    mg_uecc_vli_set(f0, f1, num_words_secp224r1); /* f0 <-- f1 */
    pow2i *= 2;
  }
}

/* Compute a = sqrt(a) (mod curve_p). */
/* Routine 3.2.8 mp_mod_sqrt_224; from
 * http://www.nsa.gov/ia/_files/nist-routines.pdf */
static void mod_sqrt_secp224r1(mg_uecc_word_t *a, MG_UECC_Curve curve) {
  (void) curve;
  bitcount_t i;
  mg_uecc_word_t e1[num_words_secp224r1];
  mg_uecc_word_t f1[num_words_secp224r1];
  mg_uecc_word_t d0[num_words_secp224r1];
  mg_uecc_word_t e0[num_words_secp224r1];
  mg_uecc_word_t f0[num_words_secp224r1];
  mg_uecc_word_t d1[num_words_secp224r1];

  /* s = a; using constant instead of random value */
  mod_sqrt_secp224r1_rp(d0, e0, f0, a, a); /* RP (d0, e0, f0, c, s) */
  mod_sqrt_secp224r1_rs(d1, e1, f1, d0, e0,
                        f0); /* RS (d1, e1, f1, d0, e0, f0) */
  for (i = 1; i <= 95; i++) {
    mg_uecc_vli_set(d0, d1, num_words_secp224r1); /* d0 <-- d1 */
    mg_uecc_vli_set(e0, e1, num_words_secp224r1); /* e0 <-- e1 */
    mg_uecc_vli_set(f0, f1, num_words_secp224r1); /* f0 <-- f1 */
    mod_sqrt_secp224r1_rs(d1, e1, f1, d0, e0,
                          f0); /* RS (d1, e1, f1, d0, e0, f0) */
    if (mg_uecc_vli_isZero(d1, num_words_secp224r1)) { /* if d1 == 0 */
      break;
    }
  }
  mg_uecc_vli_modInv(f1, e0, curve_secp224r1.p,
                     num_words_secp224r1);               /* f1 <-- 1 / e0 */
  mg_uecc_vli_modMult_fast(a, d0, f1, &curve_secp224r1); /* a  <-- d0 / e0 */
}
#endif /* MG_UECC_SUPPORT_COMPRESSED_POINT */

#if (MG_UECC_OPTIMIZATION_LEVEL > 0)
/* Computes result = product % curve_p
   from http://www.nsa.gov/ia/_files/nist-routines.pdf */
#if MG_UECC_WORD_SIZE == 1
static void vli_mmod_fast_secp224r1(uint8_t *result, uint8_t *product) {
  uint8_t tmp[num_words_secp224r1];
  int8_t carry;

  /* t */
  mg_uecc_vli_set(result, product, num_words_secp224r1);

  /* s1 */
  tmp[0] = tmp[1] = tmp[2] = tmp[3] = 0;
  tmp[4] = tmp[5] = tmp[6] = tmp[7] = 0;
  tmp[8] = tmp[9] = tmp[10] = tmp[11] = 0;
  tmp[12] = product[28];
  tmp[13] = product[29];
  tmp[14] = product[30];
  tmp[15] = product[31];
  tmp[16] = product[32];
  tmp[17] = product[33];
  tmp[18] = product[34];
  tmp[19] = product[35];
  tmp[20] = product[36];
  tmp[21] = product[37];
  tmp[22] = product[38];
  tmp[23] = product[39];
  tmp[24] = product[40];
  tmp[25] = product[41];
  tmp[26] = product[42];
  tmp[27] = product[43];
  carry = mg_uecc_vli_add(result, result, tmp, num_words_secp224r1);

  /* s2 */
  tmp[12] = product[44];
  tmp[13] = product[45];
  tmp[14] = product[46];
  tmp[15] = product[47];
  tmp[16] = product[48];
  tmp[17] = product[49];
  tmp[18] = product[50];
  tmp[19] = product[51];
  tmp[20] = product[52];
  tmp[21] = product[53];
  tmp[22] = product[54];
  tmp[23] = product[55];
  tmp[24] = tmp[25] = tmp[26] = tmp[27] = 0;
  carry += mg_uecc_vli_add(result, result, tmp, num_words_secp224r1);

  /* d1 */
  tmp[0] = product[28];
  tmp[1] = product[29];
  tmp[2] = product[30];
  tmp[3] = product[31];
  tmp[4] = product[32];
  tmp[5] = product[33];
  tmp[6] = product[34];
  tmp[7] = product[35];
  tmp[8] = product[36];
  tmp[9] = product[37];
  tmp[10] = product[38];
  tmp[11] = product[39];
  tmp[12] = product[40];
  tmp[13] = product[41];
  tmp[14] = product[42];
  tmp[15] = product[43];
  tmp[16] = product[44];
  tmp[17] = product[45];
  tmp[18] = product[46];
  tmp[19] = product[47];
  tmp[20] = product[48];
  tmp[21] = product[49];
  tmp[22] = product[50];
  tmp[23] = product[51];
  tmp[24] = product[52];
  tmp[25] = product[53];
  tmp[26] = product[54];
  tmp[27] = product[55];
  carry -= mg_uecc_vli_sub(result, result, tmp, num_words_secp224r1);

  /* d2 */
  tmp[0] = product[44];
  tmp[1] = product[45];
  tmp[2] = product[46];
  tmp[3] = product[47];
  tmp[4] = product[48];
  tmp[5] = product[49];
  tmp[6] = product[50];
  tmp[7] = product[51];
  tmp[8] = product[52];
  tmp[9] = product[53];
  tmp[10] = product[54];
  tmp[11] = product[55];
  tmp[12] = tmp[13] = tmp[14] = tmp[15] = 0;
  tmp[16] = tmp[17] = tmp[18] = tmp[19] = 0;
  tmp[20] = tmp[21] = tmp[22] = tmp[23] = 0;
  tmp[24] = tmp[25] = tmp[26] = tmp[27] = 0;
  carry -= mg_uecc_vli_sub(result, result, tmp, num_words_secp224r1);

  if (carry < 0) {
    do {
      carry += mg_uecc_vli_add(result, result, curve_secp224r1.p,
                               num_words_secp224r1);
    } while (carry < 0);
  } else {
    while (carry || mg_uecc_vli_cmp_unsafe(curve_secp224r1.p, result,
                                           num_words_secp224r1) != 1) {
      carry -= mg_uecc_vli_sub(result, result, curve_secp224r1.p,
                               num_words_secp224r1);
    }
  }
}
#elif MG_UECC_WORD_SIZE == 4
static void vli_mmod_fast_secp224r1(uint32_t *result, uint32_t *product) {
  uint32_t tmp[num_words_secp224r1];
  int carry;

  /* t */
  mg_uecc_vli_set(result, product, num_words_secp224r1);

  /* s1 */
  tmp[0] = tmp[1] = tmp[2] = 0;
  tmp[3] = product[7];
  tmp[4] = product[8];
  tmp[5] = product[9];
  tmp[6] = product[10];
  carry = mg_uecc_vli_add(result, result, tmp, num_words_secp224r1);

  /* s2 */
  tmp[3] = product[11];
  tmp[4] = product[12];
  tmp[5] = product[13];
  tmp[6] = 0;
  carry += mg_uecc_vli_add(result, result, tmp, num_words_secp224r1);

  /* d1 */
  tmp[0] = product[7];
  tmp[1] = product[8];
  tmp[2] = product[9];
  tmp[3] = product[10];
  tmp[4] = product[11];
  tmp[5] = product[12];
  tmp[6] = product[13];
  carry -= mg_uecc_vli_sub(result, result, tmp, num_words_secp224r1);

  /* d2 */
  tmp[0] = product[11];
  tmp[1] = product[12];
  tmp[2] = product[13];
  tmp[3] = tmp[4] = tmp[5] = tmp[6] = 0;
  carry -= mg_uecc_vli_sub(result, result, tmp, num_words_secp224r1);

  if (carry < 0) {
    do {
      carry += mg_uecc_vli_add(result, result, curve_secp224r1.p,
                               num_words_secp224r1);
    } while (carry < 0);
  } else {
    while (carry || mg_uecc_vli_cmp_unsafe(curve_secp224r1.p, result,
                                           num_words_secp224r1) != 1) {
      carry -= mg_uecc_vli_sub(result, result, curve_secp224r1.p,
                               num_words_secp224r1);
    }
  }
}
#else
static void vli_mmod_fast_secp224r1(uint64_t *result, uint64_t *product) {
  uint64_t tmp[num_words_secp224r1];
  int carry = 0;

  /* t */
  mg_uecc_vli_set(result, product, num_words_secp224r1);
  result[num_words_secp224r1 - 1] &= 0xffffffff;

  /* s1 */
  tmp[0] = 0;
  tmp[1] = product[3] & 0xffffffff00000000ull;
  tmp[2] = product[4];
  tmp[3] = product[5] & 0xffffffff;
  mg_uecc_vli_add(result, result, tmp, num_words_secp224r1);

  /* s2 */
  tmp[1] = product[5] & 0xffffffff00000000ull;
  tmp[2] = product[6];
  tmp[3] = 0;
  mg_uecc_vli_add(result, result, tmp, num_words_secp224r1);

  /* d1 */
  tmp[0] = (product[3] >> 32) | (product[4] << 32);
  tmp[1] = (product[4] >> 32) | (product[5] << 32);
  tmp[2] = (product[5] >> 32) | (product[6] << 32);
  tmp[3] = product[6] >> 32;
  carry -= mg_uecc_vli_sub(result, result, tmp, num_words_secp224r1);

  /* d2 */
  tmp[0] = (product[5] >> 32) | (product[6] << 32);
  tmp[1] = product[6] >> 32;
  tmp[2] = tmp[3] = 0;
  carry -= mg_uecc_vli_sub(result, result, tmp, num_words_secp224r1);

  if (carry < 0) {
    do {
      carry += mg_uecc_vli_add(result, result, curve_secp224r1.p,
                               num_words_secp224r1);
    } while (carry < 0);
  } else {
    while (mg_uecc_vli_cmp_unsafe(curve_secp224r1.p, result,
                                  num_words_secp224r1) != 1) {
      mg_uecc_vli_sub(result, result, curve_secp224r1.p, num_words_secp224r1);
    }
  }
}
#endif /* MG_UECC_WORD_SIZE */
#endif /* (MG_UECC_OPTIMIZATION_LEVEL > 0) */

#endif /* MG_UECC_SUPPORTS_secp224r1 */

#if MG_UECC_SUPPORTS_secp256r1

#if (MG_UECC_OPTIMIZATION_LEVEL > 0)
static void vli_mmod_fast_secp256r1(mg_uecc_word_t *result,
                                    mg_uecc_word_t *product);
#endif

static const struct MG_UECC_Curve_t curve_secp256r1 = {
    num_words_secp256r1,
    num_bytes_secp256r1,
    256, /* num_n_bits */
    {BYTES_TO_WORDS_8(FF, FF, FF, FF, FF, FF, FF, FF),
     BYTES_TO_WORDS_8(FF, FF, FF, FF, 00, 00, 00, 00),
     BYTES_TO_WORDS_8(00, 00, 00, 00, 00, 00, 00, 00),
     BYTES_TO_WORDS_8(01, 00, 00, 00, FF, FF, FF, FF)},
    {BYTES_TO_WORDS_8(51, 25, 63, FC, C2, CA, B9, F3),
     BYTES_TO_WORDS_8(84, 9E, 17, A7, AD, FA, E6, BC),
     BYTES_TO_WORDS_8(FF, FF, FF, FF, FF, FF, FF, FF),
     BYTES_TO_WORDS_8(00, 00, 00, 00, FF, FF, FF, FF)},
    {BYTES_TO_WORDS_8(96, C2, 98, D8, 45, 39, A1, F4),
     BYTES_TO_WORDS_8(A0, 33, EB, 2D, 81, 7D, 03, 77),
     BYTES_TO_WORDS_8(F2, 40, A4, 63, E5, E6, BC, F8),
     BYTES_TO_WORDS_8(47, 42, 2C, E1, F2, D1, 17, 6B),

     BYTES_TO_WORDS_8(F5, 51, BF, 37, 68, 40, B6, CB),
     BYTES_TO_WORDS_8(CE, 5E, 31, 6B, 57, 33, CE, 2B),
     BYTES_TO_WORDS_8(16, 9E, 0F, 7C, 4A, EB, E7, 8E),
     BYTES_TO_WORDS_8(9B, 7F, 1A, FE, E2, 42, E3, 4F)},
    {BYTES_TO_WORDS_8(4B, 60, D2, 27, 3E, 3C, CE, 3B),
     BYTES_TO_WORDS_8(F6, B0, 53, CC, B0, 06, 1D, 65),
     BYTES_TO_WORDS_8(BC, 86, 98, 76, 55, BD, EB, B3),
     BYTES_TO_WORDS_8(E7, 93, 3A, AA, D8, 35, C6, 5A)},
    &double_jacobian_default,
#if MG_UECC_SUPPORT_COMPRESSED_POINT
    &mod_sqrt_default,
#endif
    &x_side_default,
#if (MG_UECC_OPTIMIZATION_LEVEL > 0)
    &vli_mmod_fast_secp256r1
#endif
};

MG_UECC_Curve mg_uecc_secp256r1(void) {
  return &curve_secp256r1;
}

#if (MG_UECC_OPTIMIZATION_LEVEL > 0 && !asm_mmod_fast_secp256r1)
/* Computes result = product % curve_p
   from http://www.nsa.gov/ia/_files/nist-routines.pdf */
#if MG_UECC_WORD_SIZE == 1
static void vli_mmod_fast_secp256r1(uint8_t *result, uint8_t *product) {
  uint8_t tmp[num_words_secp256r1];
  int8_t carry;

  /* t */
  mg_uecc_vli_set(result, product, num_words_secp256r1);

  /* s1 */
  tmp[0] = tmp[1] = tmp[2] = tmp[3] = 0;
  tmp[4] = tmp[5] = tmp[6] = tmp[7] = 0;
  tmp[8] = tmp[9] = tmp[10] = tmp[11] = 0;
  tmp[12] = product[44];
  tmp[13] = product[45];
  tmp[14] = product[46];
  tmp[15] = product[47];
  tmp[16] = product[48];
  tmp[17] = product[49];
  tmp[18] = product[50];
  tmp[19] = product[51];
  tmp[20] = product[52];
  tmp[21] = product[53];
  tmp[22] = product[54];
  tmp[23] = product[55];
  tmp[24] = product[56];
  tmp[25] = product[57];
  tmp[26] = product[58];
  tmp[27] = product[59];
  tmp[28] = product[60];
  tmp[29] = product[61];
  tmp[30] = product[62];
  tmp[31] = product[63];
  carry = mg_uecc_vli_add(tmp, tmp, tmp, num_words_secp256r1);
  carry += mg_uecc_vli_add(result, result, tmp, num_words_secp256r1);

  /* s2 */
  tmp[12] = product[48];
  tmp[13] = product[49];
  tmp[14] = product[50];
  tmp[15] = product[51];
  tmp[16] = product[52];
  tmp[17] = product[53];
  tmp[18] = product[54];
  tmp[19] = product[55];
  tmp[20] = product[56];
  tmp[21] = product[57];
  tmp[22] = product[58];
  tmp[23] = product[59];
  tmp[24] = product[60];
  tmp[25] = product[61];
  tmp[26] = product[62];
  tmp[27] = product[63];
  tmp[28] = tmp[29] = tmp[30] = tmp[31] = 0;
  carry += mg_uecc_vli_add(tmp, tmp, tmp, num_words_secp256r1);
  carry += mg_uecc_vli_add(result, result, tmp, num_words_secp256r1);

  /* s3 */
  tmp[0] = product[32];
  tmp[1] = product[33];
  tmp[2] = product[34];
  tmp[3] = product[35];
  tmp[4] = product[36];
  tmp[5] = product[37];
  tmp[6] = product[38];
  tmp[7] = product[39];
  tmp[8] = product[40];
  tmp[9] = product[41];
  tmp[10] = product[42];
  tmp[11] = product[43];
  tmp[12] = tmp[13] = tmp[14] = tmp[15] = 0;
  tmp[16] = tmp[17] = tmp[18] = tmp[19] = 0;
  tmp[20] = tmp[21] = tmp[22] = tmp[23] = 0;
  tmp[24] = product[56];
  tmp[25] = product[57];
  tmp[26] = product[58];
  tmp[27] = product[59];
  tmp[28] = product[60];
  tmp[29] = product[61];
  tmp[30] = product[62];
  tmp[31] = product[63];
  carry += mg_uecc_vli_add(result, result, tmp, num_words_secp256r1);

  /* s4 */
  tmp[0] = product[36];
  tmp[1] = product[37];
  tmp[2] = product[38];
  tmp[3] = product[39];
  tmp[4] = product[40];
  tmp[5] = product[41];
  tmp[6] = product[42];
  tmp[7] = product[43];
  tmp[8] = product[44];
  tmp[9] = product[45];
  tmp[10] = product[46];
  tmp[11] = product[47];
  tmp[12] = product[52];
  tmp[13] = product[53];
  tmp[14] = product[54];
  tmp[15] = product[55];
  tmp[16] = product[56];
  tmp[17] = product[57];
  tmp[18] = product[58];
  tmp[19] = product[59];
  tmp[20] = product[60];
  tmp[21] = product[61];
  tmp[22] = product[62];
  tmp[23] = product[63];
  tmp[24] = product[52];
  tmp[25] = product[53];
  tmp[26] = product[54];
  tmp[27] = product[55];
  tmp[28] = product[32];
  tmp[29] = product[33];
  tmp[30] = product[34];
  tmp[31] = product[35];
  carry += mg_uecc_vli_add(result, result, tmp, num_words_secp256r1);

  /* d1 */
  tmp[0] = product[44];
  tmp[1] = product[45];
  tmp[2] = product[46];
  tmp[3] = product[47];
  tmp[4] = product[48];
  tmp[5] = product[49];
  tmp[6] = product[50];
  tmp[7] = product[51];
  tmp[8] = product[52];
  tmp[9] = product[53];
  tmp[10] = product[54];
  tmp[11] = product[55];
  tmp[12] = tmp[13] = tmp[14] = tmp[15] = 0;
  tmp[16] = tmp[17] = tmp[18] = tmp[19] = 0;
  tmp[20] = tmp[21] = tmp[22] = tmp[23] = 0;
  tmp[24] = product[32];
  tmp[25] = product[33];
  tmp[26] = product[34];
  tmp[27] = product[35];
  tmp[28] = product[40];
  tmp[29] = product[41];
  tmp[30] = product[42];
  tmp[31] = product[43];
  carry -= mg_uecc_vli_sub(result, result, tmp, num_words_secp256r1);

  /* d2 */
  tmp[0] = product[48];
  tmp[1] = product[49];
  tmp[2] = product[50];
  tmp[3] = product[51];
  tmp[4] = product[52];
  tmp[5] = product[53];
  tmp[6] = product[54];
  tmp[7] = product[55];
  tmp[8] = product[56];
  tmp[9] = product[57];
  tmp[10] = product[58];
  tmp[11] = product[59];
  tmp[12] = product[60];
  tmp[13] = product[61];
  tmp[14] = product[62];
  tmp[15] = product[63];
  tmp[16] = tmp[17] = tmp[18] = tmp[19] = 0;
  tmp[20] = tmp[21] = tmp[22] = tmp[23] = 0;
  tmp[24] = product[36];
  tmp[25] = product[37];
  tmp[26] = product[38];
  tmp[27] = product[39];
  tmp[28] = product[44];
  tmp[29] = product[45];
  tmp[30] = product[46];
  tmp[31] = product[47];
  carry -= mg_uecc_vli_sub(result, result, tmp, num_words_secp256r1);

  /* d3 */
  tmp[0] = product[52];
  tmp[1] = product[53];
  tmp[2] = product[54];
  tmp[3] = product[55];
  tmp[4] = product[56];
  tmp[5] = product[57];
  tmp[6] = product[58];
  tmp[7] = product[59];
  tmp[8] = product[60];
  tmp[9] = product[61];
  tmp[10] = product[62];
  tmp[11] = product[63];
  tmp[12] = product[32];
  tmp[13] = product[33];
  tmp[14] = product[34];
  tmp[15] = product[35];
  tmp[16] = product[36];
  tmp[17] = product[37];
  tmp[18] = product[38];
  tmp[19] = product[39];
  tmp[20] = product[40];
  tmp[21] = product[41];
  tmp[22] = product[42];
  tmp[23] = product[43];
  tmp[24] = tmp[25] = tmp[26] = tmp[27] = 0;
  tmp[28] = product[48];
  tmp[29] = product[49];
  tmp[30] = product[50];
  tmp[31] = product[51];
  carry -= mg_uecc_vli_sub(result, result, tmp, num_words_secp256r1);

  /* d4 */
  tmp[0] = product[56];
  tmp[1] = product[57];
  tmp[2] = product[58];
  tmp[3] = product[59];
  tmp[4] = product[60];
  tmp[5] = product[61];
  tmp[6] = product[62];
  tmp[7] = product[63];
  tmp[8] = tmp[9] = tmp[10] = tmp[11] = 0;
  tmp[12] = product[36];
  tmp[13] = product[37];
  tmp[14] = product[38];
  tmp[15] = product[39];
  tmp[16] = product[40];
  tmp[17] = product[41];
  tmp[18] = product[42];
  tmp[19] = product[43];
  tmp[20] = product[44];
  tmp[21] = product[45];
  tmp[22] = product[46];
  tmp[23] = product[47];
  tmp[24] = tmp[25] = tmp[26] = tmp[27] = 0;
  tmp[28] = product[52];
  tmp[29] = product[53];
  tmp[30] = product[54];
  tmp[31] = product[55];
  carry -= mg_uecc_vli_sub(result, result, tmp, num_words_secp256r1);

  if (carry < 0) {
    do {
      carry += mg_uecc_vli_add(result, result, curve_secp256r1.p,
                               num_words_secp256r1);
    } while (carry < 0);
  } else {
    while (carry || mg_uecc_vli_cmp_unsafe(curve_secp256r1.p, result,
                                           num_words_secp256r1) != 1) {
      carry -= mg_uecc_vli_sub(result, result, curve_secp256r1.p,
                               num_words_secp256r1);
    }
  }
}
#elif MG_UECC_WORD_SIZE == 4
static void vli_mmod_fast_secp256r1(uint32_t *result, uint32_t *product) {
  uint32_t tmp[num_words_secp256r1];
  int carry;

  /* t */
  mg_uecc_vli_set(result, product, num_words_secp256r1);

  /* s1 */
  tmp[0] = tmp[1] = tmp[2] = 0;
  tmp[3] = product[11];
  tmp[4] = product[12];
  tmp[5] = product[13];
  tmp[6] = product[14];
  tmp[7] = product[15];
  carry = (int) mg_uecc_vli_add(tmp, tmp, tmp, num_words_secp256r1);
  carry += (int) mg_uecc_vli_add(result, result, tmp, num_words_secp256r1);

  /* s2 */
  tmp[3] = product[12];
  tmp[4] = product[13];
  tmp[5] = product[14];
  tmp[6] = product[15];
  tmp[7] = 0;
  carry += (int) mg_uecc_vli_add(tmp, tmp, tmp, num_words_secp256r1);
  carry += (int) mg_uecc_vli_add(result, result, tmp, num_words_secp256r1);

  /* s3 */
  tmp[0] = product[8];
  tmp[1] = product[9];
  tmp[2] = product[10];
  tmp[3] = tmp[4] = tmp[5] = 0;
  tmp[6] = product[14];
  tmp[7] = product[15];
  carry += (int) mg_uecc_vli_add(result, result, tmp, num_words_secp256r1);

  /* s4 */
  tmp[0] = product[9];
  tmp[1] = product[10];
  tmp[2] = product[11];
  tmp[3] = product[13];
  tmp[4] = product[14];
  tmp[5] = product[15];
  tmp[6] = product[13];
  tmp[7] = product[8];
  carry += (int) mg_uecc_vli_add(result, result, tmp, num_words_secp256r1);

  /* d1 */
  tmp[0] = product[11];
  tmp[1] = product[12];
  tmp[2] = product[13];
  tmp[3] = tmp[4] = tmp[5] = 0;
  tmp[6] = product[8];
  tmp[7] = product[10];
  carry -= (int) mg_uecc_vli_sub(result, result, tmp, num_words_secp256r1);

  /* d2 */
  tmp[0] = product[12];
  tmp[1] = product[13];
  tmp[2] = product[14];
  tmp[3] = product[15];
  tmp[4] = tmp[5] = 0;
  tmp[6] = product[9];
  tmp[7] = product[11];
  carry -= (int) mg_uecc_vli_sub(result, result, tmp, num_words_secp256r1);

  /* d3 */
  tmp[0] = product[13];
  tmp[1] = product[14];
  tmp[2] = product[15];
  tmp[3] = product[8];
  tmp[4] = product[9];
  tmp[5] = product[10];
  tmp[6] = 0;
  tmp[7] = product[12];
  carry -= (int) mg_uecc_vli_sub(result, result, tmp, num_words_secp256r1);

  /* d4 */
  tmp[0] = product[14];
  tmp[1] = product[15];
  tmp[2] = 0;
  tmp[3] = product[9];
  tmp[4] = product[10];
  tmp[5] = product[11];
  tmp[6] = 0;
  tmp[7] = product[13];
  carry -= (int) mg_uecc_vli_sub(result, result, tmp, num_words_secp256r1);

  if (carry < 0) {
    do {
      carry += (int) mg_uecc_vli_add(result, result, curve_secp256r1.p,
                                     num_words_secp256r1);
    } while (carry < 0);
  } else {
    while (carry || mg_uecc_vli_cmp_unsafe(curve_secp256r1.p, result,
                                           num_words_secp256r1) != 1) {
      carry -= (int) mg_uecc_vli_sub(result, result, curve_secp256r1.p,
                                     num_words_secp256r1);
    }
  }
}
#else
static void vli_mmod_fast_secp256r1(uint64_t *result, uint64_t *product) {
  uint64_t tmp[num_words_secp256r1];
  int carry;

  /* t */
  mg_uecc_vli_set(result, product, num_words_secp256r1);

  /* s1 */
  tmp[0] = 0;
  tmp[1] = product[5] & 0xffffffff00000000U;
  tmp[2] = product[6];
  tmp[3] = product[7];
  carry = (int) mg_uecc_vli_add(tmp, tmp, tmp, num_words_secp256r1);
  carry += (int) mg_uecc_vli_add(result, result, tmp, num_words_secp256r1);

  /* s2 */
  tmp[1] = product[6] << 32;
  tmp[2] = (product[6] >> 32) | (product[7] << 32);
  tmp[3] = product[7] >> 32;
  carry += (int) mg_uecc_vli_add(tmp, tmp, tmp, num_words_secp256r1);
  carry += (int) mg_uecc_vli_add(result, result, tmp, num_words_secp256r1);

  /* s3 */
  tmp[0] = product[4];
  tmp[1] = product[5] & 0xffffffff;
  tmp[2] = 0;
  tmp[3] = product[7];
  carry += (int) mg_uecc_vli_add(result, result, tmp, num_words_secp256r1);

  /* s4 */
  tmp[0] = (product[4] >> 32) | (product[5] << 32);
  tmp[1] = (product[5] >> 32) | (product[6] & 0xffffffff00000000U);
  tmp[2] = product[7];
  tmp[3] = (product[6] >> 32) | (product[4] << 32);
  carry += (int) mg_uecc_vli_add(result, result, tmp, num_words_secp256r1);

  /* d1 */
  tmp[0] = (product[5] >> 32) | (product[6] << 32);
  tmp[1] = (product[6] >> 32);
  tmp[2] = 0;
  tmp[3] = (product[4] & 0xffffffff) | (product[5] << 32);
  carry -= (int) mg_uecc_vli_sub(result, result, tmp, num_words_secp256r1);

  /* d2 */
  tmp[0] = product[6];
  tmp[1] = product[7];
  tmp[2] = 0;
  tmp[3] = (product[4] >> 32) | (product[5] & 0xffffffff00000000);
  carry -= (int) mg_uecc_vli_sub(result, result, tmp, num_words_secp256r1);

  /* d3 */
  tmp[0] = (product[6] >> 32) | (product[7] << 32);
  tmp[1] = (product[7] >> 32) | (product[4] << 32);
  tmp[2] = (product[4] >> 32) | (product[5] << 32);
  tmp[3] = (product[6] << 32);
  carry -= (int) mg_uecc_vli_sub(result, result, tmp, num_words_secp256r1);

  /* d4 */
  tmp[0] = product[7];
  tmp[1] = product[4] & 0xffffffff00000000U;
  tmp[2] = product[5];
  tmp[3] = product[6] & 0xffffffff00000000U;
  carry -= (int) mg_uecc_vli_sub(result, result, tmp, num_words_secp256r1);

  if (carry < 0) {
    do {
      carry += (int) mg_uecc_vli_add(result, result, curve_secp256r1.p,
                                     num_words_secp256r1);
    } while (carry < 0);
  } else {
    while (carry || mg_uecc_vli_cmp_unsafe(curve_secp256r1.p, result,
                                           num_words_secp256r1) != 1) {
      carry -= (int) mg_uecc_vli_sub(result, result, curve_secp256r1.p,
                                     num_words_secp256r1);
    }
  }
}
#endif /* MG_UECC_WORD_SIZE */
#endif /* (MG_UECC_OPTIMIZATION_LEVEL > 0 && !asm_mmod_fast_secp256r1) */

#endif /* MG_UECC_SUPPORTS_secp256r1 */

#if MG_UECC_SUPPORTS_secp256k1

static void double_jacobian_secp256k1(mg_uecc_word_t *X1, mg_uecc_word_t *Y1,
                                      mg_uecc_word_t *Z1, MG_UECC_Curve curve);
static void x_side_secp256k1(mg_uecc_word_t *result, const mg_uecc_word_t *x,
                             MG_UECC_Curve curve);
#if (MG_UECC_OPTIMIZATION_LEVEL > 0)
static void vli_mmod_fast_secp256k1(mg_uecc_word_t *result,
                                    mg_uecc_word_t *product);
#endif

static const struct MG_UECC_Curve_t curve_secp256k1 = {
    num_words_secp256k1,
    num_bytes_secp256k1,
    256, /* num_n_bits */
    {BYTES_TO_WORDS_8(2F, FC, FF, FF, FE, FF, FF, FF),
     BYTES_TO_WORDS_8(FF, FF, FF, FF, FF, FF, FF, FF),
     BYTES_TO_WORDS_8(FF, FF, FF, FF, FF, FF, FF, FF),
     BYTES_TO_WORDS_8(FF, FF, FF, FF, FF, FF, FF, FF)},
    {BYTES_TO_WORDS_8(41, 41, 36, D0, 8C, 5E, D2, BF),
     BYTES_TO_WORDS_8(3B, A0, 48, AF, E6, DC, AE, BA),
     BYTES_TO_WORDS_8(FE, FF, FF, FF, FF, FF, FF, FF),
     BYTES_TO_WORDS_8(FF, FF, FF, FF, FF, FF, FF, FF)},
    {BYTES_TO_WORDS_8(98, 17, F8, 16, 5B, 81, F2, 59),
     BYTES_TO_WORDS_8(D9, 28, CE, 2D, DB, FC, 9B, 02),
     BYTES_TO_WORDS_8(07, 0B, 87, CE, 95, 62, A0, 55),
     BYTES_TO_WORDS_8(AC, BB, DC, F9, 7E, 66, BE, 79),

     BYTES_TO_WORDS_8(B8, D4, 10, FB, 8F, D0, 47, 9C),
     BYTES_TO_WORDS_8(19, 54, 85, A6, 48, B4, 17, FD),
     BYTES_TO_WORDS_8(A8, 08, 11, 0E, FC, FB, A4, 5D),
     BYTES_TO_WORDS_8(65, C4, A3, 26, 77, DA, 3A, 48)},
    {BYTES_TO_WORDS_8(07, 00, 00, 00, 00, 00, 00, 00),
     BYTES_TO_WORDS_8(00, 00, 00, 00, 00, 00, 00, 00),
     BYTES_TO_WORDS_8(00, 00, 00, 00, 00, 00, 00, 00),
     BYTES_TO_WORDS_8(00, 00, 00, 00, 00, 00, 00, 00)},
    &double_jacobian_secp256k1,
#if MG_UECC_SUPPORT_COMPRESSED_POINT
    &mod_sqrt_default,
#endif
    &x_side_secp256k1,
#if (MG_UECC_OPTIMIZATION_LEVEL > 0)
    &vli_mmod_fast_secp256k1
#endif
};

MG_UECC_Curve mg_uecc_secp256k1(void) {
  return &curve_secp256k1;
}

/* Double in place */
static void double_jacobian_secp256k1(mg_uecc_word_t *X1, mg_uecc_word_t *Y1,
                                      mg_uecc_word_t *Z1, MG_UECC_Curve curve) {
  /* t1 = X, t2 = Y, t3 = Z */
  mg_uecc_word_t t4[num_words_secp256k1];
  mg_uecc_word_t t5[num_words_secp256k1];

  if (mg_uecc_vli_isZero(Z1, num_words_secp256k1)) {
    return;
  }

  mg_uecc_vli_modSquare_fast(t5, Y1, curve);   /* t5 = y1^2 */
  mg_uecc_vli_modMult_fast(t4, X1, t5, curve); /* t4 = x1*y1^2 = A */
  mg_uecc_vli_modSquare_fast(X1, X1, curve);   /* t1 = x1^2 */
  mg_uecc_vli_modSquare_fast(t5, t5, curve);   /* t5 = y1^4 */
  mg_uecc_vli_modMult_fast(Z1, Y1, Z1, curve); /* t3 = y1*z1 = z3 */

  mg_uecc_vli_modAdd(Y1, X1, X1, curve->p,
                     num_words_secp256k1); /* t2 = 2*x1^2 */
  mg_uecc_vli_modAdd(Y1, Y1, X1, curve->p,
                     num_words_secp256k1); /* t2 = 3*x1^2 */
  if (mg_uecc_vli_testBit(Y1, 0)) {
    mg_uecc_word_t carry =
        mg_uecc_vli_add(Y1, Y1, curve->p, num_words_secp256k1);
    mg_uecc_vli_rshift1(Y1, num_words_secp256k1);
    Y1[num_words_secp256k1 - 1] |= carry << (MG_UECC_WORD_BITS - 1);
  } else {
    mg_uecc_vli_rshift1(Y1, num_words_secp256k1);
  }
  /* t2 = 3/2*(x1^2) = B */

  mg_uecc_vli_modSquare_fast(X1, Y1, curve); /* t1 = B^2 */
  mg_uecc_vli_modSub(X1, X1, t4, curve->p,
                     num_words_secp256k1); /* t1 = B^2 - A */
  mg_uecc_vli_modSub(X1, X1, t4, curve->p,
                     num_words_secp256k1); /* t1 = B^2 - 2A = x3 */

  mg_uecc_vli_modSub(t4, t4, X1, curve->p,
                     num_words_secp256k1);     /* t4 = A - x3 */
  mg_uecc_vli_modMult_fast(Y1, Y1, t4, curve); /* t2 = B * (A - x3) */
  mg_uecc_vli_modSub(Y1, Y1, t5, curve->p,
                     num_words_secp256k1); /* t2 = B * (A - x3) - y1^4 = y3 */
}

/* Computes result = x^3 + b. result must not overlap x. */
static void x_side_secp256k1(mg_uecc_word_t *result, const mg_uecc_word_t *x,
                             MG_UECC_Curve curve) {
  mg_uecc_vli_modSquare_fast(result, x, curve);       /* r = x^2 */
  mg_uecc_vli_modMult_fast(result, result, x, curve); /* r = x^3 */
  mg_uecc_vli_modAdd(result, result, curve->b, curve->p,
                     num_words_secp256k1); /* r = x^3 + b */
}

#if (MG_UECC_OPTIMIZATION_LEVEL > 0 && !asm_mmod_fast_secp256k1)
static void omega_mult_secp256k1(mg_uecc_word_t *result,
                                 const mg_uecc_word_t *right);
static void vli_mmod_fast_secp256k1(mg_uecc_word_t *result,
                                    mg_uecc_word_t *product) {
  mg_uecc_word_t tmp[2 * num_words_secp256k1];
  mg_uecc_word_t carry;

  mg_uecc_vli_clear(tmp, num_words_secp256k1);
  mg_uecc_vli_clear(tmp + num_words_secp256k1, num_words_secp256k1);

  omega_mult_secp256k1(tmp,
                       product + num_words_secp256k1); /* (Rq, q) = q * c */

  carry = mg_uecc_vli_add(result, product, tmp,
                          num_words_secp256k1); /* (C, r) = r + q       */
  mg_uecc_vli_clear(product, num_words_secp256k1);
  omega_mult_secp256k1(product, tmp + num_words_secp256k1); /* Rq*c */
  carry += mg_uecc_vli_add(result, result, product,
                           num_words_secp256k1); /* (C1, r) = r + Rq*c */

  while (carry > 0) {
    --carry;
    mg_uecc_vli_sub(result, result, curve_secp256k1.p, num_words_secp256k1);
  }
  if (mg_uecc_vli_cmp_unsafe(result, curve_secp256k1.p, num_words_secp256k1) >
      0) {
    mg_uecc_vli_sub(result, result, curve_secp256k1.p, num_words_secp256k1);
  }
}

#if MG_UECC_WORD_SIZE == 1
static void omega_mult_secp256k1(uint8_t *result, const uint8_t *right) {
  /* Multiply by (2^32 + 2^9 + 2^8 + 2^7 + 2^6 + 2^4 + 1). */
  mg_uecc_word_t r0 = 0;
  mg_uecc_word_t r1 = 0;
  mg_uecc_word_t r2 = 0;
  wordcount_t k;

  /* Multiply by (2^9 + 2^8 + 2^7 + 2^6 + 2^4 + 1). */
  muladd(0xD1, right[0], &r0, &r1, &r2);
  result[0] = r0;
  r0 = r1;
  r1 = r2;
  /* r2 is still 0 */

  for (k = 1; k < num_words_secp256k1; ++k) {
    muladd(0x03, right[k - 1], &r0, &r1, &r2);
    muladd(0xD1, right[k], &r0, &r1, &r2);
    result[k] = r0;
    r0 = r1;
    r1 = r2;
    r2 = 0;
  }
  muladd(0x03, right[num_words_secp256k1 - 1], &r0, &r1, &r2);
  result[num_words_secp256k1] = r0;
  result[num_words_secp256k1 + 1] = r1;
  /* add the 2^32 multiple */
  result[4 + num_words_secp256k1] =
      mg_uecc_vli_add(result + 4, result + 4, right, num_words_secp256k1);
}
#elif MG_UECC_WORD_SIZE == 4
static void omega_mult_secp256k1(uint32_t *result, const uint32_t *right) {
  /* Multiply by (2^9 + 2^8 + 2^7 + 2^6 + 2^4 + 1). */
  uint32_t carry = 0;
  wordcount_t k;

  for (k = 0; k < num_words_secp256k1; ++k) {
    uint64_t p = (uint64_t) 0x3D1 * right[k] + carry;
    result[k] = (uint32_t) p;
    carry = p >> 32;
  }
  result[num_words_secp256k1] = carry;
  /* add the 2^32 multiple */
  result[1 + num_words_secp256k1] =
      mg_uecc_vli_add(result + 1, result + 1, right, num_words_secp256k1);
}
#else
static void omega_mult_secp256k1(uint64_t *result, const uint64_t *right) {
  mg_uecc_word_t r0 = 0;
  mg_uecc_word_t r1 = 0;
  mg_uecc_word_t r2 = 0;
  wordcount_t k;

  /* Multiply by (2^32 + 2^9 + 2^8 + 2^7 + 2^6 + 2^4 + 1). */
  for (k = 0; k < num_words_secp256k1; ++k) {
    muladd(0x1000003D1ull, right[k], &r0, &r1, &r2);
    result[k] = r0;
    r0 = r1;
    r1 = r2;
    r2 = 0;
  }
  result[num_words_secp256k1] = r0;
}
#endif /* MG_UECC_WORD_SIZE */
#endif /* (MG_UECC_OPTIMIZATION_LEVEL > 0 &&  && !asm_mmod_fast_secp256k1) */

#endif /* MG_UECC_SUPPORTS_secp256k1 */

#endif /* _UECC_CURVE_SPECIFIC_H_ */

/* Returns 1 if 'point' is the point at infinity, 0 otherwise. */
#define EccPoint_isZero(point, curve) \
  mg_uecc_vli_isZero((point), (wordcount_t) ((curve)->num_words * 2))

/* Point multiplication algorithm using Montgomery's ladder with co-Z
coordinates. From http://eprint.iacr.org/2011/338.pdf
*/

/* Modify (x1, y1) => (x1 * z^2, y1 * z^3) */
static void apply_z(mg_uecc_word_t *X1, mg_uecc_word_t *Y1,
                    const mg_uecc_word_t *const Z, MG_UECC_Curve curve) {
  mg_uecc_word_t t1[MG_UECC_MAX_WORDS];

  mg_uecc_vli_modSquare_fast(t1, Z, curve);    /* z^2 */
  mg_uecc_vli_modMult_fast(X1, X1, t1, curve); /* x1 * z^2 */
  mg_uecc_vli_modMult_fast(t1, t1, Z, curve);  /* z^3 */
  mg_uecc_vli_modMult_fast(Y1, Y1, t1, curve); /* y1 * z^3 */
}

/* P = (x1, y1) => 2P, (x2, y2) => P' */
static void XYcZ_initial_double(mg_uecc_word_t *X1, mg_uecc_word_t *Y1,
                                mg_uecc_word_t *X2, mg_uecc_word_t *Y2,
                                const mg_uecc_word_t *const initial_Z,
                                MG_UECC_Curve curve) {
  mg_uecc_word_t z[MG_UECC_MAX_WORDS];
  wordcount_t num_words = curve->num_words;
  if (initial_Z) {
    mg_uecc_vli_set(z, initial_Z, num_words);
  } else {
    mg_uecc_vli_clear(z, num_words);
    z[0] = 1;
  }

  mg_uecc_vli_set(X2, X1, num_words);
  mg_uecc_vli_set(Y2, Y1, num_words);

  apply_z(X1, Y1, z, curve);
  curve->double_jacobian(X1, Y1, z, curve);
  apply_z(X2, Y2, z, curve);
}

/* Input P = (x1, y1, Z), Q = (x2, y2, Z)
   Output P' = (x1', y1', Z3), P + Q = (x3, y3, Z3)
   or P => P', Q => P + Q
*/
static void XYcZ_add(mg_uecc_word_t *X1, mg_uecc_word_t *Y1, mg_uecc_word_t *X2,
                     mg_uecc_word_t *Y2, MG_UECC_Curve curve) {
  /* t1 = X1, t2 = Y1, t3 = X2, t4 = Y2 */
  mg_uecc_word_t t5[MG_UECC_MAX_WORDS] = {0};
  wordcount_t num_words = curve->num_words;

  mg_uecc_vli_modSub(t5, X2, X1, curve->p, num_words); /* t5 = x2 - x1 */
  mg_uecc_vli_modSquare_fast(t5, t5, curve);   /* t5 = (x2 - x1)^2 = A */
  mg_uecc_vli_modMult_fast(X1, X1, t5, curve); /* t1 = x1*A = B */
  mg_uecc_vli_modMult_fast(X2, X2, t5, curve); /* t3 = x2*A = C */
  mg_uecc_vli_modSub(Y2, Y2, Y1, curve->p, num_words); /* t4 = y2 - y1 */
  mg_uecc_vli_modSquare_fast(t5, Y2, curve); /* t5 = (y2 - y1)^2 = D */

  mg_uecc_vli_modSub(t5, t5, X1, curve->p, num_words); /* t5 = D - B */
  mg_uecc_vli_modSub(t5, t5, X2, curve->p, num_words); /* t5 = D - B - C = x3 */
  mg_uecc_vli_modSub(X2, X2, X1, curve->p, num_words); /* t3 = C - B */
  mg_uecc_vli_modMult_fast(Y1, Y1, X2, curve);         /* t2 = y1*(C - B) */
  mg_uecc_vli_modSub(X2, X1, t5, curve->p, num_words); /* t3 = B - x3 */
  mg_uecc_vli_modMult_fast(Y2, Y2, X2, curve); /* t4 = (y2 - y1)*(B - x3) */
  mg_uecc_vli_modSub(Y2, Y2, Y1, curve->p, num_words); /* t4 = y3 */

  mg_uecc_vli_set(X2, t5, num_words);
}

/* Input P = (x1, y1, Z), Q = (x2, y2, Z)
   Output P + Q = (x3, y3, Z3), P - Q = (x3', y3', Z3)
   or P => P - Q, Q => P + Q
*/
static void XYcZ_addC(mg_uecc_word_t *X1, mg_uecc_word_t *Y1,
                      mg_uecc_word_t *X2, mg_uecc_word_t *Y2,
                      MG_UECC_Curve curve) {
  /* t1 = X1, t2 = Y1, t3 = X2, t4 = Y2 */
  mg_uecc_word_t t5[MG_UECC_MAX_WORDS] = {0};
  mg_uecc_word_t t6[MG_UECC_MAX_WORDS];
  mg_uecc_word_t t7[MG_UECC_MAX_WORDS];
  wordcount_t num_words = curve->num_words;

  mg_uecc_vli_modSub(t5, X2, X1, curve->p, num_words); /* t5 = x2 - x1 */
  mg_uecc_vli_modSquare_fast(t5, t5, curve);   /* t5 = (x2 - x1)^2 = A */
  mg_uecc_vli_modMult_fast(X1, X1, t5, curve); /* t1 = x1*A = B */
  mg_uecc_vli_modMult_fast(X2, X2, t5, curve); /* t3 = x2*A = C */
  mg_uecc_vli_modAdd(t5, Y2, Y1, curve->p, num_words); /* t5 = y2 + y1 */
  mg_uecc_vli_modSub(Y2, Y2, Y1, curve->p, num_words); /* t4 = y2 - y1 */

  mg_uecc_vli_modSub(t6, X2, X1, curve->p, num_words); /* t6 = C - B */
  mg_uecc_vli_modMult_fast(Y1, Y1, t6, curve); /* t2 = y1 * (C - B) = E */
  mg_uecc_vli_modAdd(t6, X1, X2, curve->p, num_words); /* t6 = B + C */
  mg_uecc_vli_modSquare_fast(X2, Y2, curve); /* t3 = (y2 - y1)^2 = D */
  mg_uecc_vli_modSub(X2, X2, t6, curve->p,
                     num_words); /* t3 = D - (B + C) = x3 */

  mg_uecc_vli_modSub(t7, X1, X2, curve->p, num_words); /* t7 = B - x3 */
  mg_uecc_vli_modMult_fast(Y2, Y2, t7, curve); /* t4 = (y2 - y1)*(B - x3) */
  mg_uecc_vli_modSub(Y2, Y2, Y1, curve->p,
                     num_words); /* t4 = (y2 - y1)*(B - x3) - E = y3 */

  mg_uecc_vli_modSquare_fast(t7, t5, curve); /* t7 = (y2 + y1)^2 = F */
  mg_uecc_vli_modSub(t7, t7, t6, curve->p,
                     num_words); /* t7 = F - (B + C) = x3' */
  mg_uecc_vli_modSub(t6, t7, X1, curve->p, num_words); /* t6 = x3' - B */
  mg_uecc_vli_modMult_fast(t6, t6, t5, curve); /* t6 = (y2+y1)*(x3' - B) */
  mg_uecc_vli_modSub(Y1, t6, Y1, curve->p,
                     num_words); /* t2 = (y2+y1)*(x3' - B) - E = y3' */

  mg_uecc_vli_set(X1, t7, num_words);
}

/* result may overlap point. */
static void EccPoint_mult(mg_uecc_word_t *result, const mg_uecc_word_t *point,
                          const mg_uecc_word_t *scalar,
                          const mg_uecc_word_t *initial_Z, bitcount_t num_bits,
                          MG_UECC_Curve curve) {
  /* R0 and R1 */
  mg_uecc_word_t Rx[2][MG_UECC_MAX_WORDS];
  mg_uecc_word_t Ry[2][MG_UECC_MAX_WORDS];
  mg_uecc_word_t z[MG_UECC_MAX_WORDS];
  bitcount_t i;
  mg_uecc_word_t nb;
  wordcount_t num_words = curve->num_words;

  mg_uecc_vli_set(Rx[1], point, num_words);
  mg_uecc_vli_set(Ry[1], point + num_words, num_words);

  XYcZ_initial_double(Rx[1], Ry[1], Rx[0], Ry[0], initial_Z, curve);

  for (i = num_bits - 2; i > 0; --i) {
    nb = !mg_uecc_vli_testBit(scalar, i);
    XYcZ_addC(Rx[1 - nb], Ry[1 - nb], Rx[nb], Ry[nb], curve);
    XYcZ_add(Rx[nb], Ry[nb], Rx[1 - nb], Ry[1 - nb], curve);
  }

  nb = !mg_uecc_vli_testBit(scalar, 0);
  XYcZ_addC(Rx[1 - nb], Ry[1 - nb], Rx[nb], Ry[nb], curve);

  /* Find final 1/Z value. */
  mg_uecc_vli_modSub(z, Rx[1], Rx[0], curve->p, num_words); /* X1 - X0 */
  mg_uecc_vli_modMult_fast(z, z, Ry[1 - nb], curve);        /* Yb * (X1 - X0) */
  mg_uecc_vli_modMult_fast(z, z, point, curve);  /* xP * Yb * (X1 - X0) */
  mg_uecc_vli_modInv(z, z, curve->p, num_words); /* 1 / (xP * Yb * (X1 - X0)) */
  /* yP / (xP * Yb * (X1 - X0)) */
  mg_uecc_vli_modMult_fast(z, z, point + num_words, curve);
  mg_uecc_vli_modMult_fast(z, z, Rx[1 - nb],
                           curve); /* Xb * yP / (xP * Yb * (X1 - X0)) */
  /* End 1/Z calculation */

  XYcZ_add(Rx[nb], Ry[nb], Rx[1 - nb], Ry[1 - nb], curve);
  apply_z(Rx[0], Ry[0], z, curve);

  mg_uecc_vli_set(result, Rx[0], num_words);
  mg_uecc_vli_set(result + num_words, Ry[0], num_words);
}

static mg_uecc_word_t regularize_k(const mg_uecc_word_t *const k,
                                   mg_uecc_word_t *k0, mg_uecc_word_t *k1,
                                   MG_UECC_Curve curve) {
  wordcount_t num_n_words = BITS_TO_WORDS(curve->num_n_bits);
  bitcount_t num_n_bits = curve->num_n_bits;
  mg_uecc_word_t carry =
      mg_uecc_vli_add(k0, k, curve->n, num_n_words) ||
      (num_n_bits < ((bitcount_t) num_n_words * MG_UECC_WORD_SIZE * 8) &&
       mg_uecc_vli_testBit(k0, num_n_bits));
  mg_uecc_vli_add(k1, k0, curve->n, num_n_words);
  return carry;
}

/* Generates a random integer in the range 0 < random < top.
   Both random and top have num_words words. */
MG_UECC_VLI_API int mg_uecc_generate_random_int(mg_uecc_word_t *random,
                                                const mg_uecc_word_t *top,
                                                wordcount_t num_words) {
  mg_uecc_word_t mask = (mg_uecc_word_t) -1;
  mg_uecc_word_t tries;
  bitcount_t num_bits = mg_uecc_vli_numBits(top, num_words);

  if (!g_rng_function) {
    return 0;
  }

  for (tries = 0; tries < MG_UECC_RNG_MAX_TRIES; ++tries) {
    if (!g_rng_function((uint8_t *) random,
                        (unsigned int) (num_words * MG_UECC_WORD_SIZE))) {
      return 0;
    }
    random[num_words - 1] &=
        mask >> ((bitcount_t) (num_words * MG_UECC_WORD_SIZE * 8 - num_bits));
    if (!mg_uecc_vli_isZero(random, num_words) &&
        mg_uecc_vli_cmp(top, random, num_words) == 1) {
      return 1;
    }
  }
  return 0;
}

static mg_uecc_word_t EccPoint_compute_public_key(mg_uecc_word_t *result,
                                                  mg_uecc_word_t *private_key,
                                                  MG_UECC_Curve curve) {
  mg_uecc_word_t tmp1[MG_UECC_MAX_WORDS];
  mg_uecc_word_t tmp2[MG_UECC_MAX_WORDS];
  mg_uecc_word_t *p2[2] = {tmp1, tmp2};
  mg_uecc_word_t *initial_Z = 0;
  mg_uecc_word_t carry;

  /* Regularize the bitcount for the private key so that attackers cannot use a
     side channel attack to learn the number of leading zeros. */
  carry = regularize_k(private_key, tmp1, tmp2, curve);

  /* If an RNG function was specified, try to get a random initial Z value to
     improve protection against side-channel attacks. */
  if (g_rng_function) {
    if (!mg_uecc_generate_random_int(p2[carry], curve->p, curve->num_words)) {
      return 0;
    }
    initial_Z = p2[carry];
  }
  EccPoint_mult(result, curve->G, p2[!carry], initial_Z,
                (bitcount_t) (curve->num_n_bits + 1), curve);

  if (EccPoint_isZero(result, curve)) {
    return 0;
  }
  return 1;
}

#if MG_UECC_WORD_SIZE == 1

MG_UECC_VLI_API void mg_uecc_vli_nativeToBytes(uint8_t *bytes, int num_bytes,
                                               const uint8_t *native) {
  wordcount_t i;
  for (i = 0; i < num_bytes; ++i) {
    bytes[i] = native[(num_bytes - 1) - i];
  }
}

MG_UECC_VLI_API void mg_uecc_vli_bytesToNative(uint8_t *native,
                                               const uint8_t *bytes,
                                               int num_bytes) {
  mg_uecc_vli_nativeToBytes(native, num_bytes, bytes);
}

#else

MG_UECC_VLI_API void mg_uecc_vli_nativeToBytes(uint8_t *bytes, int num_bytes,
                                               const mg_uecc_word_t *native) {
  int i;
  for (i = 0; i < num_bytes; ++i) {
    unsigned b = (unsigned) (num_bytes - 1 - i);
    bytes[i] = (uint8_t) (native[b / MG_UECC_WORD_SIZE] >>
                          (8 * (b % MG_UECC_WORD_SIZE)));
  }
}

MG_UECC_VLI_API void mg_uecc_vli_bytesToNative(mg_uecc_word_t *native,
                                               const uint8_t *bytes,
                                               int num_bytes) {
  int i;
  mg_uecc_vli_clear(native,
                    (wordcount_t) ((num_bytes + (MG_UECC_WORD_SIZE - 1)) /
                                   MG_UECC_WORD_SIZE));
  for (i = 0; i < num_bytes; ++i) {
    unsigned b = (unsigned) (num_bytes - 1 - i);
    native[b / MG_UECC_WORD_SIZE] |= (mg_uecc_word_t) bytes[i]
                                     << (8 * (b % MG_UECC_WORD_SIZE));
  }
}

#endif /* MG_UECC_WORD_SIZE */

int mg_uecc_make_key(uint8_t *public_key, uint8_t *private_key,
                     MG_UECC_Curve curve) {
#if MG_UECC_VLI_NATIVE_LITTLE_ENDIAN
  mg_uecc_word_t *_private = (mg_uecc_word_t *) private_key;
  mg_uecc_word_t *_public = (mg_uecc_word_t *) public_key;
#else
  mg_uecc_word_t _private[MG_UECC_MAX_WORDS];
  mg_uecc_word_t _public[MG_UECC_MAX_WORDS * 2];
#endif
  mg_uecc_word_t tries;

  for (tries = 0; tries < MG_UECC_RNG_MAX_TRIES; ++tries) {
    if (!mg_uecc_generate_random_int(_private, curve->n,
                                     BITS_TO_WORDS(curve->num_n_bits))) {
      return 0;
    }

    if (EccPoint_compute_public_key(_public, _private, curve)) {
#if MG_UECC_VLI_NATIVE_LITTLE_ENDIAN == 0
      mg_uecc_vli_nativeToBytes(private_key, BITS_TO_BYTES(curve->num_n_bits),
                                _private);
      mg_uecc_vli_nativeToBytes(public_key, curve->num_bytes, _public);
      mg_uecc_vli_nativeToBytes(public_key + curve->num_bytes, curve->num_bytes,
                                _public + curve->num_words);
#endif
      return 1;
    }
  }
  return 0;
}

int mg_uecc_shared_secret(const uint8_t *public_key, const uint8_t *private_key,
                          uint8_t *secret, MG_UECC_Curve curve) {
  mg_uecc_word_t _public[MG_UECC_MAX_WORDS * 2];
  mg_uecc_word_t _private[MG_UECC_MAX_WORDS];

  mg_uecc_word_t tmp[MG_UECC_MAX_WORDS];
  mg_uecc_word_t *p2[2] = {_private, tmp};
  mg_uecc_word_t *initial_Z = 0;
  mg_uecc_word_t carry;
  wordcount_t num_words = curve->num_words;
  wordcount_t num_bytes = curve->num_bytes;

#if MG_UECC_VLI_NATIVE_LITTLE_ENDIAN
  bcopy((uint8_t *) _private, private_key, num_bytes);
  bcopy((uint8_t *) _public, public_key, num_bytes * 2);
#else
  mg_uecc_vli_bytesToNative(_private, private_key,
                            BITS_TO_BYTES(curve->num_n_bits));
  mg_uecc_vli_bytesToNative(_public, public_key, num_bytes);
  mg_uecc_vli_bytesToNative(_public + num_words, public_key + num_bytes,
                            num_bytes);
#endif

  /* Regularize the bitcount for the private key so that attackers cannot use a
     side channel attack to learn the number of leading zeros. */
  carry = regularize_k(_private, _private, tmp, curve);

  /* If an RNG function was specified, try to get a random initial Z value to
     improve protection against side-channel attacks. */
  if (g_rng_function) {
    if (!mg_uecc_generate_random_int(p2[carry], curve->p, num_words)) {
      return 0;
    }
    initial_Z = p2[carry];
  }

  EccPoint_mult(_public, _public, p2[!carry], initial_Z,
                (bitcount_t) (curve->num_n_bits + 1), curve);
#if MG_UECC_VLI_NATIVE_LITTLE_ENDIAN
  bcopy((uint8_t *) secret, (uint8_t *) _public, num_bytes);
#else
  mg_uecc_vli_nativeToBytes(secret, num_bytes, _public);
#endif
  return !EccPoint_isZero(_public, curve);
}

#if MG_UECC_SUPPORT_COMPRESSED_POINT
void mg_uecc_compress(const uint8_t *public_key, uint8_t *compressed,
                      MG_UECC_Curve curve) {
  wordcount_t i;
  for (i = 0; i < curve->num_bytes; ++i) {
    compressed[i + 1] = public_key[i];
  }
#if MG_UECC_VLI_NATIVE_LITTLE_ENDIAN
  compressed[0] = 2 + (public_key[curve->num_bytes] & 0x01);
#else
  compressed[0] = 2 + (public_key[curve->num_bytes * 2 - 1] & 0x01);
#endif
}

void mg_uecc_decompress(const uint8_t *compressed, uint8_t *public_key,
                        MG_UECC_Curve curve) {
#if MG_UECC_VLI_NATIVE_LITTLE_ENDIAN
  mg_uecc_word_t *point = (mg_uecc_word_t *) public_key;
#else
  mg_uecc_word_t point[MG_UECC_MAX_WORDS * 2];
#endif
  mg_uecc_word_t *y = point + curve->num_words;
#if MG_UECC_VLI_NATIVE_LITTLE_ENDIAN
  bcopy(public_key, compressed + 1, curve->num_bytes);
#else
  mg_uecc_vli_bytesToNative(point, compressed + 1, curve->num_bytes);
#endif
  curve->x_side(y, point, curve);
  curve->mod_sqrt(y, curve);

  if ((uint8_t) (y[0] & 0x01) != (compressed[0] & 0x01)) {
    mg_uecc_vli_sub(y, curve->p, y, curve->num_words);
  }

#if MG_UECC_VLI_NATIVE_LITTLE_ENDIAN == 0
  mg_uecc_vli_nativeToBytes(public_key, curve->num_bytes, point);
  mg_uecc_vli_nativeToBytes(public_key + curve->num_bytes, curve->num_bytes, y);
#endif
}
#endif /* MG_UECC_SUPPORT_COMPRESSED_POINT */

MG_UECC_VLI_API int mg_uecc_valid_point(const mg_uecc_word_t *point,
                                        MG_UECC_Curve curve) {
  mg_uecc_word_t tmp1[MG_UECC_MAX_WORDS];
  mg_uecc_word_t tmp2[MG_UECC_MAX_WORDS];
  wordcount_t num_words = curve->num_words;

  /* The point at infinity is invalid. */
  if (EccPoint_isZero(point, curve)) {
    return 0;
  }

  /* x and y must be smaller than p. */
  if (mg_uecc_vli_cmp_unsafe(curve->p, point, num_words) != 1 ||
      mg_uecc_vli_cmp_unsafe(curve->p, point + num_words, num_words) != 1) {
    return 0;
  }

  mg_uecc_vli_modSquare_fast(tmp1, point + num_words, curve);
  curve->x_side(tmp2, point, curve); /* tmp2 = x^3 + ax + b */

  /* Make sure that y^2 == x^3 + ax + b */
  return (int) (mg_uecc_vli_equal(tmp1, tmp2, num_words));
}

int mg_uecc_valid_public_key(const uint8_t *public_key, MG_UECC_Curve curve) {
#if MG_UECC_VLI_NATIVE_LITTLE_ENDIAN
  mg_uecc_word_t *_public = (mg_uecc_word_t *) public_key;
#else
  mg_uecc_word_t _public[MG_UECC_MAX_WORDS * 2];
#endif

#if MG_UECC_VLI_NATIVE_LITTLE_ENDIAN == 0
  mg_uecc_vli_bytesToNative(_public, public_key, curve->num_bytes);
  mg_uecc_vli_bytesToNative(_public + curve->num_words,
                            public_key + curve->num_bytes, curve->num_bytes);
#endif
  return mg_uecc_valid_point(_public, curve);
}

int mg_uecc_compute_public_key(const uint8_t *private_key, uint8_t *public_key,
                               MG_UECC_Curve curve) {
#if MG_UECC_VLI_NATIVE_LITTLE_ENDIAN
  mg_uecc_word_t *_private = (mg_uecc_word_t *) private_key;
  mg_uecc_word_t *_public = (mg_uecc_word_t *) public_key;
#else
  mg_uecc_word_t _private[MG_UECC_MAX_WORDS];
  mg_uecc_word_t _public[MG_UECC_MAX_WORDS * 2];
#endif

#if MG_UECC_VLI_NATIVE_LITTLE_ENDIAN == 0
  mg_uecc_vli_bytesToNative(_private, private_key,
                            BITS_TO_BYTES(curve->num_n_bits));
#endif

  /* Make sure the private key is in the range [1, n-1]. */
  if (mg_uecc_vli_isZero(_private, BITS_TO_WORDS(curve->num_n_bits))) {
    return 0;
  }

  if (mg_uecc_vli_cmp(curve->n, _private, BITS_TO_WORDS(curve->num_n_bits)) !=
      1) {
    return 0;
  }

  /* Compute public key. */
  if (!EccPoint_compute_public_key(_public, _private, curve)) {
    return 0;
  }

#if MG_UECC_VLI_NATIVE_LITTLE_ENDIAN == 0
  mg_uecc_vli_nativeToBytes(public_key, curve->num_bytes, _public);
  mg_uecc_vli_nativeToBytes(public_key + curve->num_bytes, curve->num_bytes,
                            _public + curve->num_words);
#endif
  return 1;
}

/* -------- ECDSA code -------- */

static void bits2int(mg_uecc_word_t *native, const uint8_t *bits,
                     unsigned bits_size, MG_UECC_Curve curve) {
  unsigned num_n_bytes = (unsigned) BITS_TO_BYTES(curve->num_n_bits);
  unsigned num_n_words = (unsigned) BITS_TO_WORDS(curve->num_n_bits);
  int shift;
  mg_uecc_word_t carry;
  mg_uecc_word_t *ptr;

  if (bits_size > num_n_bytes) {
    bits_size = num_n_bytes;
  }

  mg_uecc_vli_clear(native, (wordcount_t) num_n_words);
#if MG_UECC_VLI_NATIVE_LITTLE_ENDIAN
  bcopy((uint8_t *) native, bits, bits_size);
#else
  mg_uecc_vli_bytesToNative(native, bits, (int) bits_size);
#endif
  if (bits_size * 8 <= (unsigned) curve->num_n_bits) {
    return;
  }
  shift = (int) bits_size * 8 - curve->num_n_bits;
  carry = 0;
  ptr = native + num_n_words;
  while (ptr-- > native) {
    mg_uecc_word_t temp = *ptr;
    *ptr = (temp >> shift) | carry;
    carry = temp << (MG_UECC_WORD_BITS - shift);
  }

  /* Reduce mod curve_n */
  if (mg_uecc_vli_cmp_unsafe(curve->n, native, (wordcount_t) num_n_words) !=
      1) {
    mg_uecc_vli_sub(native, native, curve->n, (wordcount_t) num_n_words);
  }
}

static int mg_uecc_sign_with_k_internal(const uint8_t *private_key,
                                        const uint8_t *message_hash,
                                        unsigned hash_size, mg_uecc_word_t *k,
                                        uint8_t *signature,
                                        MG_UECC_Curve curve) {
  mg_uecc_word_t tmp[MG_UECC_MAX_WORDS];
  mg_uecc_word_t s[MG_UECC_MAX_WORDS];
  mg_uecc_word_t *k2[2] = {tmp, s};
  mg_uecc_word_t *initial_Z = 0;
#if MG_UECC_VLI_NATIVE_LITTLE_ENDIAN
  mg_uecc_word_t *p = (mg_uecc_word_t *) signature;
#else
  mg_uecc_word_t p[MG_UECC_MAX_WORDS * 2];
#endif
  mg_uecc_word_t carry;
  wordcount_t num_words = curve->num_words;
  wordcount_t num_n_words = BITS_TO_WORDS(curve->num_n_bits);
  bitcount_t num_n_bits = curve->num_n_bits;

  /* Make sure 0 < k < curve_n */
  if (mg_uecc_vli_isZero(k, num_words) ||
      mg_uecc_vli_cmp(curve->n, k, num_n_words) != 1) {
    return 0;
  }

  carry = regularize_k(k, tmp, s, curve);
  /* If an RNG function was specified, try to get a random initial Z value to
     improve protection against side-channel attacks. */
  if (g_rng_function) {
    if (!mg_uecc_generate_random_int(k2[carry], curve->p, num_words)) {
      return 0;
    }
    initial_Z = k2[carry];
  }
  EccPoint_mult(p, curve->G, k2[!carry], initial_Z,
                (bitcount_t) (num_n_bits + 1), curve);
  if (mg_uecc_vli_isZero(p, num_words)) {
    return 0;
  }

  /* If an RNG function was specified, get a random number
     to prevent side channel analysis of k. */
  if (!g_rng_function) {
    mg_uecc_vli_clear(tmp, num_n_words);
    tmp[0] = 1;
  } else if (!mg_uecc_generate_random_int(tmp, curve->n, num_n_words)) {
    return 0;
  }

  /* Prevent side channel analysis of mg_uecc_vli_modInv() to determine
     bits of k / the private key by premultiplying by a random number */
  mg_uecc_vli_modMult(k, k, tmp, curve->n, num_n_words); /* k' = rand * k */
  mg_uecc_vli_modInv(k, k, curve->n, num_n_words);       /* k = 1 / k' */
  mg_uecc_vli_modMult(k, k, tmp, curve->n, num_n_words); /* k = 1 / k */

#if MG_UECC_VLI_NATIVE_LITTLE_ENDIAN == 0
  mg_uecc_vli_nativeToBytes(signature, curve->num_bytes, p); /* store r */
#endif

#if MG_UECC_VLI_NATIVE_LITTLE_ENDIAN
  bcopy((uint8_t *) tmp, private_key, BITS_TO_BYTES(curve->num_n_bits));
#else
  mg_uecc_vli_bytesToNative(tmp, private_key,
                            BITS_TO_BYTES(curve->num_n_bits)); /* tmp = d */
#endif

  s[num_n_words - 1] = 0;
  mg_uecc_vli_set(s, p, num_words);
  mg_uecc_vli_modMult(s, tmp, s, curve->n, num_n_words); /* s = r*d */

  bits2int(tmp, message_hash, hash_size, curve);
  mg_uecc_vli_modAdd(s, tmp, s, curve->n, num_n_words); /* s = e + r*d */
  mg_uecc_vli_modMult(s, s, k, curve->n, num_n_words);  /* s = (e + r*d) / k */
  if (mg_uecc_vli_numBits(s, num_n_words) > (bitcount_t) curve->num_bytes * 8) {
    return 0;
  }
#if MG_UECC_VLI_NATIVE_LITTLE_ENDIAN
  bcopy((uint8_t *) signature + curve->num_bytes, (uint8_t *) s,
        curve->num_bytes);
#else
  mg_uecc_vli_nativeToBytes(signature + curve->num_bytes, curve->num_bytes, s);
#endif
  return 1;
}

#if 0
/* For testing - sign with an explicitly specified k value */
int mg_uecc_sign_with_k(const uint8_t *private_key, const uint8_t *message_hash,
                     unsigned hash_size, const uint8_t *k, uint8_t *signature,
                     MG_UECC_Curve curve) {
  mg_uecc_word_t k2[MG_UECC_MAX_WORDS];
  bits2int(k2, k, (unsigned) BITS_TO_BYTES(curve->num_n_bits), curve);
  return mg_uecc_sign_with_k_internal(private_key, message_hash, hash_size, k2,
                                   signature, curve);
}
#endif

int mg_uecc_sign(const uint8_t *private_key, const uint8_t *message_hash,
                 unsigned hash_size, uint8_t *signature, MG_UECC_Curve curve) {
  mg_uecc_word_t k[MG_UECC_MAX_WORDS];
  mg_uecc_word_t tries;

  for (tries = 0; tries < MG_UECC_RNG_MAX_TRIES; ++tries) {
    if (!mg_uecc_generate_random_int(k, curve->n,
                                     BITS_TO_WORDS(curve->num_n_bits))) {
      return 0;
    }

    if (mg_uecc_sign_with_k_internal(private_key, message_hash, hash_size, k,
                                     signature, curve)) {
      return 1;
    }
  }
  return 0;
}

/* Compute an HMAC using K as a key (as in RFC 6979). Note that K is always
   the same size as the hash result size. */
static void HMAC_init(const MG_UECC_HashContext *hash_context,
                      const uint8_t *K) {
  uint8_t *pad = hash_context->tmp + 2 * hash_context->result_size;
  unsigned i;
  for (i = 0; i < hash_context->result_size; ++i) pad[i] = K[i] ^ 0x36;
  for (; i < hash_context->block_size; ++i) pad[i] = 0x36;

  hash_context->init_hash(hash_context);
  hash_context->update_hash(hash_context, pad, hash_context->block_size);
}

static void HMAC_update(const MG_UECC_HashContext *hash_context,
                        const uint8_t *message, unsigned message_size) {
  hash_context->update_hash(hash_context, message, message_size);
}

static void HMAC_finish(const MG_UECC_HashContext *hash_context,
                        const uint8_t *K, uint8_t *result) {
  uint8_t *pad = hash_context->tmp + 2 * hash_context->result_size;
  unsigned i;
  for (i = 0; i < hash_context->result_size; ++i) pad[i] = K[i] ^ 0x5c;
  for (; i < hash_context->block_size; ++i) pad[i] = 0x5c;

  hash_context->finish_hash(hash_context, result);

  hash_context->init_hash(hash_context);
  hash_context->update_hash(hash_context, pad, hash_context->block_size);
  hash_context->update_hash(hash_context, result, hash_context->result_size);
  hash_context->finish_hash(hash_context, result);
}

/* V = HMAC_K(V) */
static void update_V(const MG_UECC_HashContext *hash_context, uint8_t *K,
                     uint8_t *V) {
  HMAC_init(hash_context, K);
  HMAC_update(hash_context, V, hash_context->result_size);
  HMAC_finish(hash_context, K, V);
}

/* Deterministic signing, similar to RFC 6979. Differences are:
    * We just use H(m) directly rather than bits2octets(H(m))
      (it is not reduced modulo curve_n).
    * We generate a value for k (aka T) directly rather than converting
   endianness.

   Layout of hash_context->tmp: <K> | <V> | (1 byte overlapped 0x00 or 0x01) /
   <HMAC pad> */
int mg_uecc_sign_deterministic(const uint8_t *private_key,
                               const uint8_t *message_hash, unsigned hash_size,
                               const MG_UECC_HashContext *hash_context,
                               uint8_t *signature, MG_UECC_Curve curve) {
  uint8_t *K = hash_context->tmp;
  uint8_t *V = K + hash_context->result_size;
  wordcount_t num_bytes = curve->num_bytes;
  wordcount_t num_n_words = BITS_TO_WORDS(curve->num_n_bits);
  bitcount_t num_n_bits = curve->num_n_bits;
  mg_uecc_word_t tries;
  unsigned i;
  for (i = 0; i < hash_context->result_size; ++i) {
    V[i] = 0x01;
    K[i] = 0;
  }

  /* K = HMAC_K(V || 0x00 || int2octets(x) || h(m)) */
  HMAC_init(hash_context, K);
  V[hash_context->result_size] = 0x00;
  HMAC_update(hash_context, V, hash_context->result_size + 1);
  HMAC_update(hash_context, private_key, (unsigned int) num_bytes);
  HMAC_update(hash_context, message_hash, hash_size);
  HMAC_finish(hash_context, K, K);

  update_V(hash_context, K, V);

  /* K = HMAC_K(V || 0x01 || int2octets(x) || h(m)) */
  HMAC_init(hash_context, K);
  V[hash_context->result_size] = 0x01;
  HMAC_update(hash_context, V, hash_context->result_size + 1);
  HMAC_update(hash_context, private_key, (unsigned int) num_bytes);
  HMAC_update(hash_context, message_hash, hash_size);
  HMAC_finish(hash_context, K, K);

  update_V(hash_context, K, V);

  for (tries = 0; tries < MG_UECC_RNG_MAX_TRIES; ++tries) {
    mg_uecc_word_t T[MG_UECC_MAX_WORDS];
    uint8_t *T_ptr = (uint8_t *) T;
    wordcount_t T_bytes = 0;
    for (;;) {
      update_V(hash_context, K, V);
      for (i = 0; i < hash_context->result_size; ++i) {
        T_ptr[T_bytes++] = V[i];
        if (T_bytes >= num_n_words * MG_UECC_WORD_SIZE) {
          goto filled;
        }
      }
    }
  filled:
    if ((bitcount_t) num_n_words * MG_UECC_WORD_SIZE * 8 > num_n_bits) {
      mg_uecc_word_t mask = (mg_uecc_word_t) -1;
      T[num_n_words - 1] &=
          mask >>
          ((bitcount_t) (num_n_words * MG_UECC_WORD_SIZE * 8 - num_n_bits));
    }

    if (mg_uecc_sign_with_k_internal(private_key, message_hash, hash_size, T,
                                     signature, curve)) {
      return 1;
    }

    /* K = HMAC_K(V || 0x00) */
    HMAC_init(hash_context, K);
    V[hash_context->result_size] = 0x00;
    HMAC_update(hash_context, V, hash_context->result_size + 1);
    HMAC_finish(hash_context, K, K);

    update_V(hash_context, K, V);
  }
  return 0;
}

static bitcount_t smax(bitcount_t a, bitcount_t b) {
  return (a > b ? a : b);
}

int mg_uecc_verify(const uint8_t *public_key, const uint8_t *message_hash,
                   unsigned hash_size, const uint8_t *signature,
                   MG_UECC_Curve curve) {
  mg_uecc_word_t u1[MG_UECC_MAX_WORDS], u2[MG_UECC_MAX_WORDS];
  mg_uecc_word_t z[MG_UECC_MAX_WORDS];
  mg_uecc_word_t sum[MG_UECC_MAX_WORDS * 2];
  mg_uecc_word_t rx[MG_UECC_MAX_WORDS];
  mg_uecc_word_t ry[MG_UECC_MAX_WORDS];
  mg_uecc_word_t tx[MG_UECC_MAX_WORDS];
  mg_uecc_word_t ty[MG_UECC_MAX_WORDS];
  mg_uecc_word_t tz[MG_UECC_MAX_WORDS];
  const mg_uecc_word_t *points[4];
  const mg_uecc_word_t *point;
  bitcount_t num_bits;
  bitcount_t i;
#if MG_UECC_VLI_NATIVE_LITTLE_ENDIAN
  mg_uecc_word_t *_public = (mg_uecc_word_t *) public_key;
#else
  mg_uecc_word_t _public[MG_UECC_MAX_WORDS * 2];
#endif
  mg_uecc_word_t r[MG_UECC_MAX_WORDS], s[MG_UECC_MAX_WORDS];
  wordcount_t num_words = curve->num_words;
  wordcount_t num_n_words = BITS_TO_WORDS(curve->num_n_bits);

  rx[num_n_words - 1] = 0;
  r[num_n_words - 1] = 0;
  s[num_n_words - 1] = 0;

#if MG_UECC_VLI_NATIVE_LITTLE_ENDIAN
  bcopy((uint8_t *) r, signature, curve->num_bytes);
  bcopy((uint8_t *) s, signature + curve->num_bytes, curve->num_bytes);
#else
  mg_uecc_vli_bytesToNative(_public, public_key, curve->num_bytes);
  mg_uecc_vli_bytesToNative(_public + num_words, public_key + curve->num_bytes,
                            curve->num_bytes);
  mg_uecc_vli_bytesToNative(r, signature, curve->num_bytes);
  mg_uecc_vli_bytesToNative(s, signature + curve->num_bytes, curve->num_bytes);
#endif

  /* r, s must not be 0. */
  if (mg_uecc_vli_isZero(r, num_words) || mg_uecc_vli_isZero(s, num_words)) {
    return 0;
  }

  /* r, s must be < n. */
  if (mg_uecc_vli_cmp_unsafe(curve->n, r, num_n_words) != 1 ||
      mg_uecc_vli_cmp_unsafe(curve->n, s, num_n_words) != 1) {
    return 0;
  }

  /* Calculate u1 and u2. */
  mg_uecc_vli_modInv(z, s, curve->n, num_n_words); /* z = 1/s */
  u1[num_n_words - 1] = 0;
  bits2int(u1, message_hash, hash_size, curve);
  mg_uecc_vli_modMult(u1, u1, z, curve->n, num_n_words); /* u1 = e/s */
  mg_uecc_vli_modMult(u2, r, z, curve->n, num_n_words);  /* u2 = r/s */

  /* Calculate sum = G + Q. */
  mg_uecc_vli_set(sum, _public, num_words);
  mg_uecc_vli_set(sum + num_words, _public + num_words, num_words);
  mg_uecc_vli_set(tx, curve->G, num_words);
  mg_uecc_vli_set(ty, curve->G + num_words, num_words);
  mg_uecc_vli_modSub(z, sum, tx, curve->p, num_words); /* z = x2 - x1 */
  XYcZ_add(tx, ty, sum, sum + num_words, curve);
  mg_uecc_vli_modInv(z, z, curve->p, num_words); /* z = 1/z */
  apply_z(sum, sum + num_words, z, curve);

  /* Use Shamir's trick to calculate u1*G + u2*Q */
  points[0] = 0;
  points[1] = curve->G;
  points[2] = _public;
  points[3] = sum;
  num_bits = smax(mg_uecc_vli_numBits(u1, num_n_words),
                  mg_uecc_vli_numBits(u2, num_n_words));
  point =
      points[(!!mg_uecc_vli_testBit(u1, (bitcount_t) (num_bits - 1))) |
             ((!!mg_uecc_vli_testBit(u2, (bitcount_t) (num_bits - 1))) << 1)];
  mg_uecc_vli_set(rx, point, num_words);
  mg_uecc_vli_set(ry, point + num_words, num_words);
  mg_uecc_vli_clear(z, num_words);
  z[0] = 1;

  for (i = num_bits - 2; i >= 0; --i) {
    mg_uecc_word_t index;
    curve->double_jacobian(rx, ry, z, curve);

    index = (!!mg_uecc_vli_testBit(u1, i)) |
            (mg_uecc_word_t) ((!!mg_uecc_vli_testBit(u2, i)) << 1);
    point = points[index];
    if (point) {
      mg_uecc_vli_set(tx, point, num_words);
      mg_uecc_vli_set(ty, point + num_words, num_words);
      apply_z(tx, ty, z, curve);
      mg_uecc_vli_modSub(tz, rx, tx, curve->p, num_words); /* Z = x2 - x1 */
      XYcZ_add(tx, ty, rx, ry, curve);
      mg_uecc_vli_modMult_fast(z, z, tz, curve);
    }
  }

  mg_uecc_vli_modInv(z, z, curve->p, num_words); /* Z = 1/Z */
  apply_z(rx, ry, z, curve);

  /* v = x1 (mod n) */
  if (mg_uecc_vli_cmp_unsafe(curve->n, rx, num_n_words) != 1) {
    mg_uecc_vli_sub(rx, rx, curve->n, num_n_words);
  }

  /* Accept only if v == r. */
  return (int) (mg_uecc_vli_equal(rx, r, num_words));
}

#if MG_UECC_ENABLE_VLI_API

unsigned mg_uecc_curve_num_words(MG_UECC_Curve curve) {
  return curve->num_words;
}

unsigned mg_uecc_curve_num_bytes(MG_UECC_Curve curve) {
  return curve->num_bytes;
}

unsigned mg_uecc_curve_num_bits(MG_UECC_Curve curve) {
  return curve->num_bytes * 8;
}

unsigned mg_uecc_curve_num_n_words(MG_UECC_Curve curve) {
  return BITS_TO_WORDS(curve->num_n_bits);
}

unsigned mg_uecc_curve_num_n_bytes(MG_UECC_Curve curve) {
  return BITS_TO_BYTES(curve->num_n_bits);
}

unsigned mg_uecc_curve_num_n_bits(MG_UECC_Curve curve) {
  return curve->num_n_bits;
}

const mg_uecc_word_t *mg_uecc_curve_p(MG_UECC_Curve curve) {
  return curve->p;
}

const mg_uecc_word_t *mg_uecc_curve_n(MG_UECC_Curve curve) {
  return curve->n;
}

const mg_uecc_word_t *mg_uecc_curve_G(MG_UECC_Curve curve) {
  return curve->G;
}

const mg_uecc_word_t *mg_uecc_curve_b(MG_UECC_Curve curve) {
  return curve->b;
}

#if MG_UECC_SUPPORT_COMPRESSED_POINT
void mg_uecc_vli_mod_sqrt(mg_uecc_word_t *a, MG_UECC_Curve curve) {
  curve->mod_sqrt(a, curve);
}
#endif

void mg_uecc_vli_mmod_fast(mg_uecc_word_t *result, mg_uecc_word_t *product,
                           MG_UECC_Curve curve) {
#if (MG_UECC_OPTIMIZATION_LEVEL > 0)
  curve->mmod_fast(result, product);
#else
  mg_uecc_vli_mmod(result, product, curve->p, curve->num_words);
#endif
}

void mg_uecc_point_mult(mg_uecc_word_t *result, const mg_uecc_word_t *point,
                        const mg_uecc_word_t *scalar, MG_UECC_Curve curve) {
  mg_uecc_word_t tmp1[MG_UECC_MAX_WORDS];
  mg_uecc_word_t tmp2[MG_UECC_MAX_WORDS];
  mg_uecc_word_t *p2[2] = {tmp1, tmp2};
  mg_uecc_word_t carry = regularize_k(scalar, tmp1, tmp2, curve);

  EccPoint_mult(result, point, p2[!carry], 0, curve->num_n_bits + 1, curve);
}

#endif  /* MG_UECC_ENABLE_VLI_API */
#endif  // MG_TLS_BUILTIN
// End of uecc BSD-2

#ifdef MG_ENABLE_LINES
#line 1 "src/tls_x25519.c"
#endif
/**
 * Adapted from STROBE: https://strobe.sourceforge.io/
 * Copyright (c) 2015-2016 Cryptography Research, Inc.
 * Author: Mike Hamburg
 * License: MIT License
 */




#if MG_TLS == MG_TLS_BUILTIN

const uint8_t X25519_BASE_POINT[X25519_BYTES] = {9};

#define X25519_WBITS 32

typedef uint32_t limb_t;
typedef uint64_t dlimb_t;
typedef int64_t sdlimb_t;

#define NLIMBS (256 / X25519_WBITS)
typedef limb_t mg_fe[NLIMBS];

static limb_t umaal(limb_t *carry, limb_t acc, limb_t mand, limb_t mier) {
  dlimb_t tmp = (dlimb_t) mand * mier + acc + *carry;
  *carry = (limb_t) (tmp >> X25519_WBITS);
  return (limb_t) tmp;
}

// These functions are implemented in terms of umaal on ARM
static limb_t adc(limb_t *carry, limb_t acc, limb_t mand) {
  dlimb_t total = (dlimb_t) *carry + acc + mand;
  *carry = (limb_t) (total >> X25519_WBITS);
  return (limb_t) total;
}

static limb_t adc0(limb_t *carry, limb_t acc) {
  dlimb_t total = (dlimb_t) *carry + acc;
  *carry = (limb_t) (total >> X25519_WBITS);
  return (limb_t) total;
}

// - Precondition: carry is small.
// - Invariant: result of propagate is < 2^255 + 1 word
// - In particular, always less than 2p.
// - Also, output x >= min(x,19)
static void propagate(mg_fe x, limb_t over) {
  unsigned i;
  limb_t carry;
  over = x[NLIMBS - 1] >> (X25519_WBITS - 1) | over << 1;
  x[NLIMBS - 1] &= ~((limb_t) 1 << (X25519_WBITS - 1));

  carry = over * 19;
  for (i = 0; i < NLIMBS; i++) {
    x[i] = adc0(&carry, x[i]);
  }
}

static void add(mg_fe out, const mg_fe a, const mg_fe b) {
  unsigned i;
  limb_t carry = 0;
  for (i = 0; i < NLIMBS; i++) {
    out[i] = adc(&carry, a[i], b[i]);
  }
  propagate(out, carry);
}

static void sub(mg_fe out, const mg_fe a, const mg_fe b) {
  unsigned i;
  sdlimb_t carry = -38;
  for (i = 0; i < NLIMBS; i++) {
    carry = carry + a[i] - b[i];
    out[i] = (limb_t) carry;
    carry >>= X25519_WBITS;
  }
  propagate(out, (limb_t) (1 + carry));
}

// `b` can contain less than 8 limbs, thus we use `limb_t *` instead of `mg_fe`
// to avoid build warnings
static void mul(mg_fe out, const mg_fe a, const limb_t *b, unsigned nb) {
  limb_t accum[2 * NLIMBS] = {0};
  unsigned i, j;

  limb_t carry2;
  for (i = 0; i < nb; i++) {
    limb_t mand = b[i];
    carry2 = 0;
    for (j = 0; j < NLIMBS; j++) {
      limb_t tmp;                        // "a" may be misaligned
      memcpy(&tmp, &a[j], sizeof(tmp));  // So make an aligned copy
      accum[i + j] = umaal(&carry2, accum[i + j], mand, tmp);
    }
    accum[i + j] = carry2;
  }

  carry2 = 0;
  for (j = 0; j < NLIMBS; j++) {
    out[j] = umaal(&carry2, accum[j], 38, accum[j + NLIMBS]);
  }
  propagate(out, carry2);
}

static void sqr(mg_fe out, const mg_fe a) {
  mul(out, a, a, NLIMBS);
}
static void mul1(mg_fe out, const mg_fe a) {
  mul(out, a, out, NLIMBS);
}
static void sqr1(mg_fe a) {
  mul1(a, a);
}

static void condswap(limb_t a[2 * NLIMBS], limb_t b[2 * NLIMBS],
                     limb_t doswap) {
  unsigned i;
  for (i = 0; i < 2 * NLIMBS; i++) {
    limb_t xor_ab = (a[i] ^ b[i]) & doswap;
    a[i] ^= xor_ab;
    b[i] ^= xor_ab;
  }
}

// Canonicalize a field element x, reducing it to the least residue which is
// congruent to it mod 2^255-19
// - Precondition: x < 2^255 + 1 word
static limb_t canon(mg_fe x) {
  // First, add 19.
  unsigned i;
  limb_t carry0 = 19;
  limb_t res;
  sdlimb_t carry;
  for (i = 0; i < NLIMBS; i++) {
    x[i] = adc0(&carry0, x[i]);
  }
  propagate(x, carry0);

  // Here, 19 <= x2 < 2^255
  // - This is because we added 19, so before propagate it can't be less
  // than 19. After propagate, it still can't be less than 19, because if
  // propagate does anything it adds 19.
  // - We know that the high bit must be clear, because either the input was ~
  // 2^255 + one word + 19 (in which case it propagates to at most 2 words) or
  // it was < 2^255. So now, if we subtract 19, we will get back to something in
  // [0,2^255-19).
  carry = -19;
  res = 0;
  for (i = 0; i < NLIMBS; i++) {
    carry += x[i];
    res |= x[i] = (limb_t) carry;
    carry >>= X25519_WBITS;
  }
  return (limb_t) (((dlimb_t) res - 1) >> X25519_WBITS);
}

static const limb_t a24[1] = {121665};

static void ladder_part1(mg_fe xs[5]) {
  limb_t *x2 = xs[0], *z2 = xs[1], *x3 = xs[2], *z3 = xs[3], *t1 = xs[4];
  add(t1, x2, z2);                                 // t1 = A
  sub(z2, x2, z2);                                 // z2 = B
  add(x2, x3, z3);                                 // x2 = C
  sub(z3, x3, z3);                                 // z3 = D
  mul1(z3, t1);                                    // z3 = DA
  mul1(x2, z2);                                    // x3 = BC
  add(x3, z3, x2);                                 // x3 = DA+CB
  sub(z3, z3, x2);                                 // z3 = DA-CB
  sqr1(t1);                                        // t1 = AA
  sqr1(z2);                                        // z2 = BB
  sub(x2, t1, z2);                                 // x2 = E = AA-BB
  mul(z2, x2, a24, sizeof(a24) / sizeof(a24[0]));  // z2 = E*a24
  add(z2, z2, t1);                                 // z2 = E*a24 + AA
}

static void ladder_part2(mg_fe xs[5], const mg_fe x1) {
  limb_t *x2 = xs[0], *z2 = xs[1], *x3 = xs[2], *z3 = xs[3], *t1 = xs[4];
  sqr1(z3);         // z3 = (DA-CB)^2
  mul1(z3, x1);     // z3 = x1 * (DA-CB)^2
  sqr1(x3);         // x3 = (DA+CB)^2
  mul1(z2, x2);     // z2 = AA*(E*a24+AA)
  sub(x2, t1, x2);  // x2 = BB again
  mul1(x2, t1);     // x2 = AA*BB
}

static void x25519_core(mg_fe xs[5], const uint8_t scalar[X25519_BYTES],
                        const uint8_t *x1, int clamp) {
  int i;
  mg_fe x1_limbs;
  limb_t swap = 0;
  limb_t *x2 = xs[0], *x3 = xs[2], *z3 = xs[3];
  memset(xs, 0, 4 * sizeof(mg_fe));
  x2[0] = z3[0] = 1;
  for (i = 0; i < NLIMBS; i++) {
    x3[i] = x1_limbs[i] =
        MG_U32(x1[i * 4 + 3], x1[i * 4 + 2], x1[i * 4 + 1], x1[i * 4]);
  }

  for (i = 255; i >= 0; i--) {
    uint8_t bytei = scalar[i / 8];
    limb_t doswap;
    if (clamp) {
      if (i / 8 == 0) {
        bytei &= (uint8_t) ~7U;
      } else if (i / 8 == X25519_BYTES - 1) {
        bytei &= 0x7F;
        bytei |= 0x40;
      }
    }
    doswap = 0 - (limb_t) ((bytei >> (i % 8)) & 1);
    condswap(x2, x3, swap ^ doswap);
    swap = doswap;

    ladder_part1(xs);
    ladder_part2(xs, (const limb_t *) x1_limbs);
  }
  condswap(x2, x3, swap);
}

int mg_tls_x25519(uint8_t out[X25519_BYTES], const uint8_t scalar[X25519_BYTES],
                  const uint8_t x1[X25519_BYTES], int clamp) {
  int i, ret;
  mg_fe xs[5], out_limbs;
  limb_t *x2, *z2, *z3, *prev;
  static const struct {
    uint8_t a, c, n;
  } steps[13] = {{2, 1, 1},  {2, 1, 1},  {4, 2, 3},  {2, 4, 6},  {3, 1, 1},
                 {3, 2, 12}, {4, 3, 25}, {2, 3, 25}, {2, 4, 50}, {3, 2, 125},
                 {3, 1, 2},  {3, 1, 2},  {3, 1, 1}};
  x25519_core(xs, scalar, x1, clamp);

  // Precomputed inversion chain
  x2 = xs[0];
  z2 = xs[1];
  z3 = xs[3];

  prev = z2;
  for (i = 0; i < 13; i++) {
    int j;
    limb_t *a = xs[steps[i].a];
    for (j = steps[i].n; j > 0; j--) {
      sqr(a, prev);
      prev = a;
    }
    mul1(a, xs[steps[i].c]);
  }

  // Here prev = z3
  // x2 /= z2
  mul(out_limbs, x2, z3, NLIMBS);
  ret = (int) canon(out_limbs);
  if (!clamp) ret = 0;
  for (i = 0; i < NLIMBS; i++) {
    uint32_t n = out_limbs[i];
    out[i * 4] = (uint8_t) (n & 0xff);
    out[i * 4 + 1] = (uint8_t) ((n >> 8) & 0xff);
    out[i * 4 + 2] = (uint8_t) ((n >> 16) & 0xff);
    out[i * 4 + 3] = (uint8_t) ((n >> 24) & 0xff);
  }
  return ret;
}

#endif

#ifdef MG_ENABLE_LINES
#line 1 "src/url.c"
#endif


struct url {
  size_t key, user, pass, host, port, uri, end;
};

int mg_url_is_ssl(const char *url) {
  return strncmp(url, "wss:", 4) == 0 || strncmp(url, "https:", 6) == 0 ||
         strncmp(url, "mqtts:", 6) == 0 || strncmp(url, "ssl:", 4) == 0 ||
         strncmp(url, "tls:", 4) == 0 || strncmp(url, "tcps:", 5) == 0;
}

static struct url urlparse(const char *url) {
  size_t i;
  struct url u;
  memset(&u, 0, sizeof(u));
  for (i = 0; url[i] != '\0'; i++) {
    if (url[i] == '/' && i > 0 && u.host == 0 && url[i - 1] == '/') {
      u.host = i + 1;
      u.port = 0;
    } else if (url[i] == ']') {
      u.port = 0;  // IPv6 URLs, like http://[::1]/bar
    } else if (url[i] == ':' && u.port == 0 && u.uri == 0) {
      u.port = i + 1;
    } else if (url[i] == '@' && u.user == 0 && u.pass == 0 && u.uri == 0) {
      u.user = u.host;
      u.pass = u.port;
      u.host = i + 1;
      u.port = 0;
    } else if (url[i] == '/' && u.host && u.uri == 0) {
      u.uri = i;
    }
  }
  u.end = i;
#if 0
  printf("[%s] %d %d %d %d %d\n", url, u.user, u.pass, u.host, u.port, u.uri);
#endif
  return u;
}

struct mg_str mg_url_host(const char *url) {
  struct url u = urlparse(url);
  size_t n = u.port  ? u.port - u.host - 1
             : u.uri ? u.uri - u.host
                     : u.end - u.host;
  struct mg_str s = mg_str_n(url + u.host, n);
  return s;
}

const char *mg_url_uri(const char *url) {
  struct url u = urlparse(url);
  return u.uri ? url + u.uri : "/";
}

unsigned short mg_url_port(const char *url) {
  struct url u = urlparse(url);
  unsigned short port = 0;
  if (strncmp(url, "http:", 5) == 0 || strncmp(url, "ws:", 3) == 0) port = 80;
  if (strncmp(url, "wss:", 4) == 0 || strncmp(url, "https:", 6) == 0)
    port = 443;
  if (strncmp(url, "mqtt:", 5) == 0) port = 1883;
  if (strncmp(url, "mqtts:", 6) == 0) port = 8883;
  if (u.port) port = (unsigned short) atoi(url + u.port);
  return port;
}

struct mg_str mg_url_user(const char *url) {
  struct url u = urlparse(url);
  struct mg_str s = mg_str("");
  if (u.user && (u.pass || u.host)) {
    size_t n = u.pass ? u.pass - u.user - 1 : u.host - u.user - 1;
    s = mg_str_n(url + u.user, n);
  }
  return s;
}

struct mg_str mg_url_pass(const char *url) {
  struct url u = urlparse(url);
  struct mg_str s = mg_str_n("", 0UL);
  if (u.pass && u.host) {
    size_t n = u.host - u.pass - 1;
    s = mg_str_n(url + u.pass, n);
  }
  return s;
}

#ifdef MG_ENABLE_LINES
#line 1 "src/util.c"
#endif



// Not using memset for zeroing memory, cause it can be dropped by compiler
// See https://github.com/cesanta/mongoose/pull/1265
void mg_bzero(volatile unsigned char *buf, size_t len) {
  if (buf != NULL) {
    while (len--) *buf++ = 0;
  }
}

#if MG_ENABLE_CUSTOM_RANDOM
#else
bool mg_random(void *buf, size_t len) {
  bool success = false;
  unsigned char *p = (unsigned char *) buf;
#if MG_ARCH == MG_ARCH_ESP32
  while (len--) *p++ = (unsigned char) (esp_random() & 255);
  success = true;
#elif MG_ARCH == MG_ARCH_PICOSDK
  while (len--) *p++ = (unsigned char) (get_rand_32() & 255);
  success = true;
#elif MG_ARCH == MG_ARCH_WIN32
#if defined(_MSC_VER) && _MSC_VER < 1700
  static bool initialised = false;
  static HCRYPTPROV hProv;
  // CryptGenRandom() implementation earlier than 2008 is weak, see
  // https://en.wikipedia.org/wiki/CryptGenRandom
  if (!initialised) {
    initialised = CryptAcquireContext(&hProv, NULL, NULL, PROV_RSA_FULL,
                                      CRYPT_VERIFYCONTEXT);
  }
  if (initialised) success = CryptGenRandom(hProv, len, p);
#else
  size_t i;
  for (i = 0; i < len; i++) {
    unsigned int rand_v;
    if (rand_s(&rand_v) == 0) {
      p[i] = (unsigned char) (rand_v & 255);
    } else {
      break;
    }
  }
  success = (i == len);
#endif

#elif MG_ARCH == MG_ARCH_UNIX
  FILE *fp = fopen("/dev/urandom", "rb");
  if (fp != NULL) {
    if (fread(buf, 1, len, fp) == len) success = true;
    fclose(fp);
  }
#endif
  // If everything above did not work, fallback to a pseudo random generator
  if (success == false) {
    MG_ERROR(("Weak RNG: using rand()"));
    while (len--) *p++ = (unsigned char) (rand() & 255);
  }
  return success;
}
#endif

char *mg_random_str(char *buf, size_t len) {
  size_t i;
  mg_random(buf, len);
  for (i = 0; i < len; i++) {
    uint8_t c = ((uint8_t *) buf)[i] % 62U;
    buf[i] = i == len - 1 ? (char) '\0'            // 0-terminate last byte
             : c < 26     ? (char) ('a' + c)       // lowercase
             : c < 52     ? (char) ('A' + c - 26)  // uppercase
                          : (char) ('0' + c - 52);     // numeric
  }
  return buf;
}

uint32_t mg_crc32(uint32_t crc, const char *buf, size_t len) {
  static const uint32_t crclut[16] = {
      // table for polynomial 0xEDB88320 (reflected)
      0x00000000, 0x1DB71064, 0x3B6E20C8, 0x26D930AC, 0x76DC4190, 0x6B6B51F4,
      0x4DB26158, 0x5005713C, 0xEDB88320, 0xF00F9344, 0xD6D6A3E8, 0xCB61B38C,
      0x9B64C2B0, 0x86D3D2D4, 0xA00AE278, 0xBDBDF21C};
  crc = ~crc;
  while (len--) {
    uint8_t b = *(uint8_t *) buf++;
    crc = crclut[(crc ^ b) & 0x0F] ^ (crc >> 4);
    crc = crclut[(crc ^ (b >> 4)) & 0x0F] ^ (crc >> 4);
  }
  return ~crc;
}

static int isbyte(int n) {
  return n >= 0 && n <= 255;
}

static int parse_net(const char *spec, uint32_t *net, uint32_t *mask) {
  int n, a, b, c, d, slash = 32, len = 0;
  if ((sscanf(spec, "%d.%d.%d.%d/%d%n", &a, &b, &c, &d, &slash, &n) == 5 ||
       sscanf(spec, "%d.%d.%d.%d%n", &a, &b, &c, &d, &n) == 4) &&
      isbyte(a) && isbyte(b) && isbyte(c) && isbyte(d) && slash >= 0 &&
      slash < 33) {
    len = n;
    *net = ((uint32_t) a << 24) | ((uint32_t) b << 16) | ((uint32_t) c << 8) |
           (uint32_t) d;
    *mask = slash ? (uint32_t) (0xffffffffU << (32 - slash)) : (uint32_t) 0;
  }
  return len;
}

int mg_check_ip_acl(struct mg_str acl, struct mg_addr *remote_ip) {
  struct mg_str entry;
  int allowed = acl.len == 0 ? '+' : '-';  // If any ACL is set, deny by default
  uint32_t remote_ip4;
  if (remote_ip->is_ip6) {
    return -1;  // TODO(): handle IPv6 ACL and addresses
  } else {      // IPv4
    memcpy((void *) &remote_ip4, remote_ip->ip, sizeof(remote_ip4));
    while (mg_span(acl, &entry, &acl, ',')) {
      uint32_t net, mask;
      if (entry.buf[0] != '+' && entry.buf[0] != '-') return -1;
      if (parse_net(&entry.buf[1], &net, &mask) == 0) return -2;
      if ((mg_ntohl(remote_ip4) & mask) == net) allowed = entry.buf[0];
    }
  }
  return allowed == '+';
}

bool mg_path_is_sane(const struct mg_str path) {
  const char *s = path.buf;
  size_t n = path.len;
  if (path.buf[0] == '.' && path.buf[1] == '.') return false;  // Starts with ..
  for (; s[0] != '\0' && n > 0; s++, n--) {
    if ((s[0] == '/' || s[0] == '\\') && n >= 2) {   // Subdir?
      if (s[1] == '.' && s[2] == '.') return false;  // Starts with ..
    }
  }
  return true;
}

#if MG_ENABLE_CUSTOM_MILLIS
#else
uint64_t mg_millis(void) {
#if MG_ARCH == MG_ARCH_WIN32
  return GetTickCount();
#elif MG_ARCH == MG_ARCH_PICOSDK
  return time_us_64() / 1000;
#elif MG_ARCH == MG_ARCH_ESP8266 || MG_ARCH == MG_ARCH_ESP32 || \
    MG_ARCH == MG_ARCH_FREERTOS
  return xTaskGetTickCount() * portTICK_PERIOD_MS;
#elif MG_ARCH == MG_ARCH_AZURERTOS
  return tx_time_get() * (1000 /* MS per SEC */ / TX_TIMER_TICKS_PER_SECOND);
#elif MG_ARCH == MG_ARCH_TIRTOS
  return (uint64_t) Clock_getTicks();
#elif MG_ARCH == MG_ARCH_ZEPHYR
  return (uint64_t) k_uptime_get();
#elif MG_ARCH == MG_ARCH_CMSIS_RTOS1
  return (uint64_t) rt_time_get();
#elif MG_ARCH == MG_ARCH_CMSIS_RTOS2
  return (uint64_t) ((osKernelGetTickCount() * 1000) / osKernelGetTickFreq());
#elif MG_ARCH == MG_ARCH_RTTHREAD
  return (uint64_t) ((rt_tick_get() * 1000) / RT_TICK_PER_SECOND);
#elif MG_ARCH == MG_ARCH_UNIX && defined(__APPLE__)
  // Apple CLOCK_MONOTONIC_RAW is equivalent to CLOCK_BOOTTIME on linux
  // Apple CLOCK_UPTIME_RAW is equivalent to CLOCK_MONOTONIC_RAW on linux
  return clock_gettime_nsec_np(CLOCK_UPTIME_RAW) / 1000000;
#elif MG_ARCH == MG_ARCH_UNIX
  struct timespec ts = {0, 0};
  // See #1615 - prefer monotonic clock
#if defined(CLOCK_MONOTONIC_RAW)
  // Raw hardware-based time that is not subject to NTP adjustment
  clock_gettime(CLOCK_MONOTONIC_RAW, &ts);
#elif defined(CLOCK_MONOTONIC)
  // Affected by the incremental adjustments performed by adjtime and NTP
  clock_gettime(CLOCK_MONOTONIC, &ts);
#else
  // Affected by discontinuous jumps in the system time and by the incremental
  // adjustments performed by adjtime and NTP
  clock_gettime(CLOCK_REALTIME, &ts);
#endif
  return ((uint64_t) ts.tv_sec * 1000 + (uint64_t) ts.tv_nsec / 1000000);
#elif defined(ARDUINO)
  return (uint64_t) millis();
#else
  return (uint64_t) (time(NULL) * 1000);
#endif
}
#endif

// network format equates big endian order
uint16_t mg_ntohs(uint16_t net) {
  return MG_LOAD_BE16(&net);
}

uint32_t mg_ntohl(uint32_t net) {
  return MG_LOAD_BE32(&net);
}

void mg_delayms(unsigned int ms) {
  uint64_t to = mg_millis() + ms + 1;
  while (mg_millis() < to) (void) 0;
}

#ifdef MG_ENABLE_LINES
#line 1 "src/wifi_dummy.c"
#endif


#if (!defined(MG_ENABLE_DRIVER_PICO_W) || !MG_ENABLE_DRIVER_PICO_W) && \
    (!defined(MG_ENABLE_DRIVER_CYW) || !MG_ENABLE_DRIVER_CYW)

bool mg_wifi_scan(void) {
  MG_ERROR(("No Wi-Fi driver enabled"));
  return false;
}

bool mg_wifi_connect(char *ssid, char *pass) {
  (void) ssid;
  (void) pass;
  return mg_wifi_scan();
}

bool mg_wifi_disconnect(void) {
  return mg_wifi_scan();
}

bool mg_wifi_ap_start(char *ssid, char *pass, unsigned int channel) {
  (void) ssid;
  (void) pass;
  (void) channel;
  return mg_wifi_scan();
}

bool mg_wifi_ap_stop(void) {
  return mg_wifi_scan();
}

#endif

#ifdef MG_ENABLE_LINES
#line 1 "src/ws.c"
#endif











struct ws_msg {
  uint8_t flags;
  size_t header_len;
  size_t data_len;
};

size_t mg_ws_vprintf(struct mg_connection *c, int op, const char *fmt,
                     va_list *ap) {
  size_t len = c->send.len;
  size_t n = mg_vxprintf(mg_pfn_iobuf, &c->send, fmt, ap);
  mg_ws_wrap(c, c->send.len - len, op);
  return n;
}

size_t mg_ws_printf(struct mg_connection *c, int op, const char *fmt, ...) {
  size_t len = 0;
  va_list ap;
  va_start(ap, fmt);
  len = mg_ws_vprintf(c, op, fmt, &ap);
  va_end(ap);
  return len;
}

static void ws_handshake(struct mg_connection *c, const struct mg_str *wskey,
                         const struct mg_str *wsproto, const char *fmt,
                         va_list *ap) {
  const char *magic = "258EAFA5-E914-47DA-95CA-C5AB0DC85B11";
  unsigned char sha[20], b64_sha[30];

  mg_sha1_ctx sha_ctx;
  mg_sha1_init(&sha_ctx);
  mg_sha1_update(&sha_ctx, (unsigned char *) wskey->buf, wskey->len);
  mg_sha1_update(&sha_ctx, (unsigned char *) magic, 36);
  mg_sha1_final(sha, &sha_ctx);
  mg_base64_encode(sha, sizeof(sha), (char *) b64_sha, sizeof(b64_sha));
  mg_xprintf(mg_pfn_iobuf, &c->send,
             "HTTP/1.1 101 Switching Protocols\r\n"
             "Upgrade: websocket\r\n"
             "Connection: Upgrade\r\n"
             "Sec-WebSocket-Accept: %s\r\n",
             b64_sha);
  if (fmt != NULL) mg_vxprintf(mg_pfn_iobuf, &c->send, fmt, ap);
  if (wsproto != NULL) {
    mg_printf(c, "Sec-WebSocket-Protocol: %.*s\r\n", (int) wsproto->len,
              wsproto->buf);
  }
  mg_send(c, "\r\n", 2);
}

static uint32_t be32(const uint8_t *p) {
  return (((uint32_t) p[3]) << 0) | (((uint32_t) p[2]) << 8) |
         (((uint32_t) p[1]) << 16) | (((uint32_t) p[0]) << 24);
}

static size_t ws_process(uint8_t *buf, size_t len, struct ws_msg *msg) {
  size_t i, n = 0, mask_len = 0;
  memset(msg, 0, sizeof(*msg));
  if (len >= 2) {
    n = buf[1] & 0x7f;                // Frame length
    mask_len = buf[1] & 128 ? 4 : 0;  // last bit is a mask bit
    msg->flags = buf[0];
    if (n < 126 && len >= mask_len) {
      msg->data_len = n;
      msg->header_len = 2 + mask_len;
    } else if (n == 126 && len >= 4 + mask_len) {
      msg->header_len = 4 + mask_len;
      msg->data_len = (((size_t) buf[2]) << 8) | buf[3];
    } else if (len >= 10 + mask_len) {
      msg->header_len = 10 + mask_len;
      msg->data_len =
          (size_t) (((uint64_t) be32(buf + 2) << 32) + be32(buf + 6));
    }
  }
  // Sanity check, and integer overflow protection for the boundary check below
  // data_len should not be larger than 1 Gb
  if (msg->data_len > 1024 * 1024 * 1024) return 0;
  if (msg->header_len + msg->data_len > len) return 0;
  if (mask_len > 0) {
    uint8_t *p = buf + msg->header_len, *m = p - mask_len;
    for (i = 0; i < msg->data_len; i++) p[i] ^= m[i & 3];
  }
  return msg->header_len + msg->data_len;
}

static size_t mkhdr(size_t len, int op, bool is_client, uint8_t *buf) {
  size_t n = 0;
  buf[0] = (uint8_t) (op | 128);
  if (len < 126) {
    buf[1] = (unsigned char) len;
    n = 2;
  } else if (len < 65536) {
    uint16_t tmp = mg_htons((uint16_t) len);
    buf[1] = 126;
    memcpy(&buf[2], &tmp, sizeof(tmp));
    n = 4;
  } else {
    uint32_t tmp;
    buf[1] = 127;
    tmp = mg_htonl((uint32_t) (((uint64_t) len) >> 32));
    memcpy(&buf[2], &tmp, sizeof(tmp));
    tmp = mg_htonl((uint32_t) (len & 0xffffffffU));
    memcpy(&buf[6], &tmp, sizeof(tmp));
    n = 10;
  }
  if (is_client) {
    buf[1] |= 1 << 7;  // Set masking flag
    mg_random(&buf[n], 4);
    n += 4;
  }
  return n;
}

static void mg_ws_mask(struct mg_connection *c, size_t len) {
  if (c->is_client && c->send.buf != NULL) {
    size_t i;
    uint8_t *p = c->send.buf + c->send.len - len, *mask = p - 4;
    for (i = 0; i < len; i++) p[i] ^= mask[i & 3];
  }
}

size_t mg_ws_send(struct mg_connection *c, const void *buf, size_t len,
                  int op) {
  uint8_t header[14];
  size_t header_len = mkhdr(len, op, c->is_client, header);
  if (!mg_send(c, header, header_len)) return 0;
  if (!mg_send(c, buf, len)) return header_len;
  MG_VERBOSE(("WS out: %d [%.*s]", (int) len, (int) len, buf));
  mg_ws_mask(c, len);
  return header_len + len;
}

static bool mg_ws_client_handshake(struct mg_connection *c) {
  int n = mg_http_get_request_len(c->recv.buf, c->recv.len);
  if (n < 0) {
    mg_error(c, "not http");  // Some just, not an HTTP request
  } else if (n > 0) {
    if (n < 15 || memcmp(c->recv.buf + 9, "101", 3) != 0) {
      mg_error(c, "ws handshake error");
    } else {
      struct mg_http_message hm;
      if (mg_http_parse((char *) c->recv.buf, c->recv.len, &hm)) {
        c->is_websocket = 1;
        mg_call(c, MG_EV_WS_OPEN, &hm);
      } else {
        mg_error(c, "ws handshake error");
      }
    }
    mg_iobuf_del(&c->recv, 0, (size_t) n);
  } else {
    return true;  // Request is not yet received, quit event handler
  }
  return false;  // Continue event handler
}

static void mg_ws_cb(struct mg_connection *c, int ev, void *ev_data) {
  struct ws_msg msg;
  size_t ofs = (size_t) c->pfn_data;

  // assert(ofs < c->recv.len);
  if (ev == MG_EV_READ) {
    if (c->is_client && !c->is_websocket && mg_ws_client_handshake(c)) return;

    while (ws_process(c->recv.buf + ofs, c->recv.len - ofs, &msg) > 0) {
      char *s = (char *) c->recv.buf + ofs + msg.header_len;
      struct mg_ws_message m = {{s, msg.data_len}, msg.flags};
      size_t len = msg.header_len + msg.data_len;
      uint8_t final = msg.flags & 128, op = msg.flags & 15;
      // MG_VERBOSE ("fin %d op %d len %d [%.*s]", final, op,
      //                       (int) m.data.len, (int) m.data.len, m.data.buf));
      switch (op) {
        case WEBSOCKET_OP_CONTINUE:
          mg_call(c, MG_EV_WS_CTL, &m);
          break;
        case WEBSOCKET_OP_PING:
          MG_DEBUG(("%s", "WS PONG"));
          mg_ws_send(c, s, msg.data_len, WEBSOCKET_OP_PONG);
          mg_call(c, MG_EV_WS_CTL, &m);
          break;
        case WEBSOCKET_OP_PONG:
          mg_call(c, MG_EV_WS_CTL, &m);
          break;
        case WEBSOCKET_OP_TEXT:
        case WEBSOCKET_OP_BINARY:
          if (final) mg_call(c, MG_EV_WS_MSG, &m);
          break;
        case WEBSOCKET_OP_CLOSE:
          MG_DEBUG(("%lu WS CLOSE", c->id));
          mg_call(c, MG_EV_WS_CTL, &m);
          // Echo the payload of the received CLOSE message back to the sender
          mg_ws_send(c, m.data.buf, m.data.len, WEBSOCKET_OP_CLOSE);
          c->is_draining = 1;
          break;
        default:
          // Per RFC6455, close conn when an unknown op is recvd
          mg_error(c, "unknown WS op %d", op);
          break;
      }

      // Handle fragmented frames: strip header, keep in c->recv
      if (final == 0 || op == 0) {
        if (op) ofs++, len--, msg.header_len--;       // First frame
        mg_iobuf_del(&c->recv, ofs, msg.header_len);  // Strip header
        len -= msg.header_len;
        ofs += len;
        c->pfn_data = (void *) ofs;
        // MG_INFO(("FRAG %d [%.*s]", (int) ofs, (int) ofs, c->recv.buf));
      }
      // Remove non-fragmented frame
      if (final && op) mg_iobuf_del(&c->recv, ofs, len);
      // Last chunk of the fragmented frame
      if (final && !op) {
        m.flags = c->recv.buf[0];
        m.data = mg_str_n((char *) &c->recv.buf[1], (size_t) (ofs - 1));
        mg_call(c, MG_EV_WS_MSG, &m);
        mg_iobuf_del(&c->recv, 0, ofs);
        ofs = 0;
        c->pfn_data = NULL;
      }
    }
  }
  (void) ev_data;
}

struct mg_connection *mg_ws_connect(struct mg_mgr *mgr, const char *url,
                                    mg_event_handler_t fn, void *fn_data,
                                    const char *fmt, ...) {
  struct mg_connection *c = mg_connect(mgr, url, fn, fn_data);
  if (c != NULL) {
    char nonce[16], key[30];
    struct mg_str host = mg_url_host(url);
    mg_random(nonce, sizeof(nonce));
    mg_base64_encode((unsigned char *) nonce, sizeof(nonce), key, sizeof(key));
    mg_xprintf(mg_pfn_iobuf, &c->send,
               "GET %s HTTP/1.1\r\n"
               "Upgrade: websocket\r\n"
               "Host: %.*s\r\n"
               "Connection: Upgrade\r\n"
               "Sec-WebSocket-Version: 13\r\n"
               "Sec-WebSocket-Key: %s\r\n",
               mg_url_uri(url), (int) host.len, host.buf, key);
    if (fmt != NULL) {
      va_list ap;
      va_start(ap, fmt);
      mg_vxprintf(mg_pfn_iobuf, &c->send, fmt, &ap);
      va_end(ap);
    }
    mg_xprintf(mg_pfn_iobuf, &c->send, "\r\n");
    c->pfn = mg_ws_cb;
    c->pfn_data = NULL;
  }
  return c;
}

void mg_ws_upgrade(struct mg_connection *c, struct mg_http_message *hm,
                   const char *fmt, ...) {
  struct mg_str *wskey = mg_http_get_header(hm, "Sec-WebSocket-Key");
  c->pfn = mg_ws_cb;
  c->pfn_data = NULL;
  if (wskey == NULL) {
    mg_http_reply(c, 426, "", "WS upgrade expected\n");
    c->is_draining = 1;
  } else {
    struct mg_str *wsproto = mg_http_get_header(hm, "Sec-WebSocket-Protocol");
    va_list ap;
    va_start(ap, fmt);
    ws_handshake(c, wskey, wsproto, fmt, &ap);
    va_end(ap);
    c->is_websocket = 1;
    c->is_resp = 0;
    mg_call(c, MG_EV_WS_OPEN, hm);
  }
}

size_t mg_ws_wrap(struct mg_connection *c, size_t len, int op) {
  uint8_t header[14], *p;
  size_t header_len = mkhdr(len, op, c->is_client, header);

  // NOTE: order of operations is important!
  if (mg_iobuf_add(&c->send, c->send.len, NULL, header_len) != 0) {
    p = &c->send.buf[c->send.len - len];         // p points to data
    memmove(p, p - header_len, len);             // Shift data
    memcpy(p - header_len, header, header_len);  // Prepend header
    mg_ws_mask(c, len);                          // Mask data
  }
  return c->send.len;
}

#ifdef MG_ENABLE_LINES
#line 1 "src/drivers/cmsis.c"
#endif
// https://arm-software.github.io/CMSIS_5/Driver/html/index.html

#if MG_ENABLE_TCPIP && defined(MG_ENABLE_DRIVER_CMSIS) && MG_ENABLE_DRIVER_CMSIS





extern ARM_DRIVER_ETH_MAC Driver_ETH_MAC0;
extern ARM_DRIVER_ETH_PHY Driver_ETH_PHY0;

static struct mg_tcpip_if *s_ifp;

static void mac_cb(uint32_t);
static bool cmsis_init(struct mg_tcpip_if *);
static bool cmsis_poll(struct mg_tcpip_if *, bool);
static size_t cmsis_tx(const void *, size_t, struct mg_tcpip_if *);
static size_t cmsis_rx(void *, size_t, struct mg_tcpip_if *);

struct mg_tcpip_driver mg_tcpip_driver_cmsis = {cmsis_init, cmsis_tx, NULL,
                                                cmsis_poll};

static bool cmsis_init(struct mg_tcpip_if *ifp) {
  ARM_ETH_MAC_ADDR addr;
  s_ifp = ifp;

  ARM_DRIVER_ETH_MAC *mac = &Driver_ETH_MAC0;
  ARM_DRIVER_ETH_PHY *phy = &Driver_ETH_PHY0;
  ARM_ETH_MAC_CAPABILITIES cap = mac->GetCapabilities();
  if (mac->Initialize(mac_cb) != ARM_DRIVER_OK) return false;
  if (phy->Initialize(mac->PHY_Read, mac->PHY_Write) != ARM_DRIVER_OK)
    return false;
  if (cap.event_rx_frame == 0)  // polled mode driver
    mg_tcpip_driver_cmsis.rx = cmsis_rx;
  mac->PowerControl(ARM_POWER_FULL);
  if (cap.mac_address) {  // driver provides MAC address
    mac->GetMacAddress(&addr);
    memcpy(ifp->mac, &addr, sizeof(ifp->mac));
  } else {  // we provide MAC address
    memcpy(&addr, ifp->mac, sizeof(addr));
    mac->SetMacAddress(&addr);
  }
  phy->PowerControl(ARM_POWER_FULL);
  phy->SetInterface(cap.media_interface);
  phy->SetMode(ARM_ETH_PHY_AUTO_NEGOTIATE);
  return true;
}

static size_t cmsis_tx(const void *buf, size_t len, struct mg_tcpip_if *ifp) {
  ARM_DRIVER_ETH_MAC *mac = &Driver_ETH_MAC0;
  if (mac->SendFrame(buf, (uint32_t) len, 0) != ARM_DRIVER_OK) {
    ifp->nerr++;
    return 0;
  }
  ifp->nsent++;
  return len;
}

static bool cmsis_poll(struct mg_tcpip_if *ifp, bool s1) {
  if (!s1) return false;
  ARM_DRIVER_ETH_PHY *phy = &Driver_ETH_PHY0;
  ARM_DRIVER_ETH_MAC *mac = &Driver_ETH_MAC0;
  bool up = (phy->GetLinkState() == ARM_ETH_LINK_UP) ? 1 : 0;  // link state
  if ((ifp->state == MG_TCPIP_STATE_DOWN) && up) {             // just went up
    ARM_ETH_LINK_INFO st = phy->GetLinkInfo();
    mac->Control(ARM_ETH_MAC_CONFIGURE,
                 (st.speed << ARM_ETH_MAC_SPEED_Pos) |
                     (st.duplex << ARM_ETH_MAC_DUPLEX_Pos) |
                     ARM_ETH_MAC_ADDRESS_BROADCAST);
    MG_DEBUG(("Link is %uM %s-duplex",
              (st.speed == 2) ? 1000
              : st.speed      ? 100
                              : 10,
              st.duplex ? "full" : "half"));
    mac->Control(ARM_ETH_MAC_CONTROL_TX, 1);
    mac->Control(ARM_ETH_MAC_CONTROL_RX, 1);
  } else if ((ifp->state != MG_TCPIP_STATE_DOWN) && !up) {  // just went down
    mac->Control(ARM_ETH_MAC_FLUSH,
                 ARM_ETH_MAC_FLUSH_TX | ARM_ETH_MAC_FLUSH_RX);
    mac->Control(ARM_ETH_MAC_CONTROL_TX, 0);
    mac->Control(ARM_ETH_MAC_CONTROL_RX, 0);
  }
  return up;
}

static void mac_cb(uint32_t ev) {
  if ((ev & ARM_ETH_MAC_EVENT_RX_FRAME) == 0) return;
  ARM_DRIVER_ETH_MAC *mac = &Driver_ETH_MAC0;
  uint32_t len = mac->GetRxFrameSize();  // CRC already stripped
  if (len >= 60 && len <= 1518) {        // proper frame
    char *p;
    if (mg_queue_book(&s_ifp->recv_queue, &p, len) >= len) {  // have room
      if ((len = mac->ReadFrame((uint8_t *) p, len)) > 0) {   // copy succeeds
        mg_queue_add(&s_ifp->recv_queue, len);
        s_ifp->nrecv++;
      }
      return;
    }
    s_ifp->ndrop++;
  }
  mac->ReadFrame(NULL, 0);  // otherwise, discard
}

static size_t cmsis_rx(void *buf, size_t buflen, struct mg_tcpip_if *ifp) {
  ARM_DRIVER_ETH_MAC *mac = &Driver_ETH_MAC0;
  uint32_t len = mac->GetRxFrameSize();  // CRC already stripped
  if (len >= 60 && len <= 1518 &&
      ((len = mac->ReadFrame(buf, (uint32_t) buflen)) > 0))
    return len;
  if (len > 0) mac->ReadFrame(NULL, 0);  // discard bad frames
  (void) ifp;
  return 0;
}

#endif

#ifdef MG_ENABLE_LINES
#line 1 "src/drivers/cyw.c"
#endif



#if MG_ENABLE_TCPIP && defined(MG_ENABLE_DRIVER_CYW) && MG_ENABLE_DRIVER_CYW


static struct mg_tcpip_if *s_ifp;
static bool s_link, s_auth, s_join;

static bool cyw_init(struct mg_tcpip_driver_cyw_firmware *fw, uint8_t *mac);
static void cyw_poll(void);

static bool mg_tcpip_driver_cyw_init(struct mg_tcpip_if *ifp) {
  struct mg_tcpip_driver_cyw_data *d =
      (struct mg_tcpip_driver_cyw_data *) ifp->driver_data;
  if (MG_BIG_ENDIAN) {
    MG_ERROR(("Big-endian host"));
    return false;
  }
  s_ifp = ifp;
  s_link = s_auth = s_join = false;
  if (!cyw_init(d->fw, ifp->mac)) return false;

  if (d->apmode) {
    MG_DEBUG(("Starting AP '%s' (%u)", d->apssid, d->apchannel));
    return mg_wifi_ap_start(d->apssid, d->appass, d->apchannel);
  } else if (d->ssid != NULL && d->pass != NULL) {
    MG_DEBUG(("Connecting to '%s'", d->ssid));
    return mg_wifi_connect(d->ssid, d->pass);
  }
  return true;
}

static size_t mg_cyw_tx(unsigned int ifc, void *data, size_t len);
size_t mg_tcpip_driver_cyw_output(const void *buf, size_t len,
                                  struct mg_tcpip_if *ifp) {
  struct mg_tcpip_driver_cyw_data *d =
      (struct mg_tcpip_driver_cyw_data *) ifp->driver_data;
  return mg_cyw_tx(d->apmode ? 1 : 0, (void *) buf, len) >= len ? len : 0;
}

static bool mg_tcpip_driver_cyw_poll(struct mg_tcpip_if *ifp, bool s1) {
  cyw_poll();
  if (!s1) return false;
  struct mg_tcpip_driver_cyw_data *d =
      (struct mg_tcpip_driver_cyw_data *) ifp->driver_data;
  return d->apmode ? s_link : s_link && s_auth && s_join;
}

struct mg_tcpip_driver mg_tcpip_driver_cyw = {mg_tcpip_driver_cyw_init,
                                              mg_tcpip_driver_cyw_output, NULL,
                                              mg_tcpip_driver_cyw_poll};

// - DS:
// https://www.mouser.com/datasheet/2/196/Infineon_CYW43439_DataSheet_v03_00_EN-3074791.pdf
// - WHD: https://github.com/Infineon/wifi-host-driver
//
//              |  e   <-- event data
//              |-----
//          net | vnd   <-- network (TCP/IP) | vendor header (Broadcom (bcm))
//         -----|-----
//  IOCTL | ETH | ETH  <-- IOCTL/IOVAR: chip control | ETH: Ethernet header
// -------|-----|-----
//   CDC  | BDC | BDC
// ------- ----- -----
//        SDPCM        <-- includes SDIO bus arbitration, not used in SPI
// -------------------
//    SPI   |  SDIO    <-- padded to 32-bit | 64-bytes
//
// - SDPCM has 3 channels (control, data, and asynchronous data)
// - SPI (and SDIO) has 4 "functions", F0 to F3, to access different
// blocks in the chip, like the SPI/SDIO controller, chip backplane, and 2 DMA
// I/Os; these are usually handled by SDPCM but we need to explicitly access
// the I/O controller and chip backplane during initialization

// Processor core firmware is loaded to TCM RAM, along with module-dependent
// (hardware design) NVRAM data, via the chip backplane access through the bus
// Once the chip has been initialized, information regarding regulatory
// constraints (CLM blob, “Country Locale Matrix”), is loaded as an IOVAR. This
// is tied to the module being certified, hence it is also module-dependent.
// - Result: chip firmware + module NVRAM data + module CLM blob

#pragma pack(push, 1)
// all little endian

struct cdc_hdr {
  uint32_t cmd;   // ioctl command value
  uint16_t olen;  // output buflen
  uint16_t ilen;  // input buflen (excludes header)
  uint32_t flags;
  uint32_t status;
};

struct bdc_hdr {
  uint8_t flags;     // Flags
  uint8_t priority;  // 802.1d Priority (low 3 bits)
  uint8_t flags2;
  uint8_t data_offset;  // Offset from end of BDC header to packet data, in
                        // 4-uint8_t words. Leaves room for optional headers.
};

struct sdpcm_sw_hdr {
  uint8_t sequence;           // Sequence number of pkt
  uint8_t channel_and_flags;  // IOCTL/IOVAR or User Data or Event
  uint8_t next_length;
  uint8_t header_length;  // Offset to BDC or CDC header
  uint8_t wireless_flow_control;
  uint8_t bus_data_credit;  // Credit from WLAN Chip
  uint8_t _reserved[2];
};

struct sdpcm_hdr {
  uint16_t len;
  uint16_t _len;  // ~len
  struct sdpcm_sw_hdr sw_hdr;
};

struct data_hdr {
  struct sdpcm_hdr sdpcm;
  uint8_t pad[2];
  struct bdc_hdr bdc;
};

// gSPI, DS 4.2.1 Fig.12, 2-bit field
#define CYW_SD_FUNC_BUS 0   // F0
#define CYW_SD_FUNC_CHIP 1  // F1
#define CYW_SD_FUNC_WLAN 2  // F2

#define CYW_SDPCM_CTRL_HDR 0
#define CYW_SDPCM_ASYNC_HDR 1
#define CYW_SDPCM_DATA_HDR 2

#pragma pack(pop)

static uint8_t s_tx_seqno;
static uint32_t txdata[2048 / 4], resp[2048 / 4];

static void cyw_handle_cdc(struct cdc_hdr *cdc, size_t len);
static void cyw_handle_bdc(struct bdc_hdr *bdc, size_t len);
static void cyw_handle_bdc_evnt(struct bdc_hdr *bdc, size_t len);

static size_t cyw_spi_poll(uint8_t *dest);

// High-level comm stuff

static void cyw_poll(void) {
  struct sdpcm_hdr *sdpcm = (struct sdpcm_hdr *) resp;
  unsigned int channel;
  if (cyw_spi_poll((uint8_t *) resp) == 0) return;  // BUS DEPENDENCY
  if ((sdpcm->len ^ sdpcm->_len) != 0xffff || sdpcm->len < sizeof(*sdpcm) ||
      sdpcm->len > 2048 - sizeof(*sdpcm))
    return;
  channel = sdpcm->sw_hdr.channel_and_flags & 0x0F;
  if (channel == CYW_SDPCM_CTRL_HDR) {
    if (sdpcm->len >= sizeof(*sdpcm) + sizeof(struct cdc_hdr)) {
      struct cdc_hdr *cdc =
          (struct cdc_hdr *) ((size_t) sdpcm + sdpcm->sw_hdr.header_length);
      size_t len = sdpcm->len - sdpcm->sw_hdr.header_length;
      cyw_handle_cdc(cdc, len);
    }
  } else if (channel == CYW_SDPCM_DATA_HDR) {
    if (sdpcm->len >= sizeof(*sdpcm) + sizeof(struct bdc_hdr)) {
      struct bdc_hdr *bdc =
          (struct bdc_hdr *) ((size_t) sdpcm + sdpcm->sw_hdr.header_length);
      size_t len = sdpcm->len - sdpcm->sw_hdr.header_length;
      cyw_handle_bdc(bdc, len);
    }
  } else if (channel == CYW_SDPCM_ASYNC_HDR) {
    struct bdc_hdr *bdc =
        (struct bdc_hdr *) ((size_t) sdpcm + sdpcm->sw_hdr.header_length);
    size_t len_ = sdpcm->len - sdpcm->sw_hdr.header_length;
    cyw_handle_bdc_evnt(bdc, len_);
  }  // else silently discard
}

// WLAN frame reception
static void cyw_handle_bdc(struct bdc_hdr *bdc, size_t len) {
  uint8_t *payload = (uint8_t *) &bdc[bdc->data_offset + 1];
  mg_tcpip_qwrite(payload, len - (payload - (uint8_t *) bdc), s_ifp);
}

static size_t cyw_bus_tx(uint32_t *data, uint16_t len);

// WLAN frame transmission
static size_t mg_cyw_tx(unsigned int ifc, void *data, size_t len) {
  struct data_hdr *hdr = (struct data_hdr *) txdata;
  uint16_t txlen = (uint16_t) (len + sizeof(*hdr));
  memset(txdata, 0, sizeof(*hdr));
  memcpy((uint8_t *) txdata + sizeof(*hdr), data, len);
  // TODO(): hdr->bdc.priority = map IP to TOS if supporting QoS/ToS
  hdr->bdc.flags = 2 << 4;  // BDC version 2
  hdr->bdc.flags2 = ifc;    // 0 -> STA, 1 -> AP
  // hdr->bdc.data_offset = 0; // actually zeroed above
  hdr->sdpcm.len = txlen;
  hdr->sdpcm._len = (uint16_t) ~txlen;
  hdr->sdpcm.sw_hdr.sequence = ++s_tx_seqno;
  hdr->sdpcm.sw_hdr.channel_and_flags = CYW_SDPCM_DATA_HDR,
  hdr->sdpcm.sw_hdr.header_length = offsetof(struct data_hdr, bdc);
  return cyw_bus_tx(txdata, txlen);
}

// WLAN event handling
#pragma pack(push, 1)
// all in network order

struct eth_hdr {  // TODO(scaprile) reuse 'eth' in net_builtin.c
  uint8_t dest[6];
  uint8_t src[6];
  uint16_t type;
};

struct bcm_vendor_hdr {
  uint16_t subtype;  // vendor specific: 0x8001
  uint16_t length;   // bytes following this field
  uint8_t version;   // 0
  uint8_t oui[3];    // vendor specific: 0x00 0x10 0x18
  uint16_t usr_subtype;
};

struct bcm_evnt_hdr {
  uint16_t version;  // 1: fields up to ifname; 2: as shown
  uint16_t flags;
  uint32_t event_type;
  uint32_t status;
  uint32_t reason;
  uint32_t auth_type;
  uint32_t datalen;
  uint8_t addr[6];  // Station address (if applicable)
  char ifname[16];
  uint8_t ifidx;
  uint8_t bss_cfg_idx;
};

struct evnt_msg {
  struct eth_hdr eth;
  //  struct vendor_hdr; but we only handle Broadcom (Wi-Fi processor) events
  struct bcm_vendor_hdr bcm;
  struct bcm_evnt_hdr event;
};

#pragma pack(pop)

struct scan_result;
static void cyw_handle_scan_result(uint32_t status, struct scan_result *data,
                                   size_t len);

static void cyw_handle_bdc_evnt(struct bdc_hdr *bdc, size_t len) {
  struct evnt_msg *msg = (struct evnt_msg *) &bdc[bdc->data_offset + 1];
  MG_VERBOSE(("%u bytes event", len));
  if (mg_log_level >= MG_LL_VERBOSE) mg_hexdump((void *) bdc, len);
  if (mg_ntohs(msg->eth.type) != 0x886C || msg->bcm.oui[0] != 0x00 ||
      msg->bcm.oui[1] != 0x10 || msg->bcm.oui[2] != 0x18)
    return;  // discard if not Broadcom
  if (mg_ntohl(msg->event.datalen) <=
      len - ((uint8_t *) msg - (uint8_t *) bdc)) {
    uint32_t event_type = mg_ntohl(msg->event.event_type);
    uint32_t status = mg_ntohl(msg->event.status);
    uint32_t reason = mg_ntohl(msg->event.reason);
    uint16_t flags = mg_ntohs(msg->event.flags);
    MG_DEBUG(("BCM event %lu %lu %lu %p", event_type, status, reason, flags));
    if (event_type == 16 && status == 0) {  // Link
      s_link = flags & 1;
    } else if (event_type == 46 && s_link) {  // PSK sup with link up
      if (status == 6) {                      // Keyed
      } else if ((status == 4 || status == 8 || status == 10) &&
                 reason == 15) {  // Wait M1/M3/G1
        MG_ERROR(("AUTH TIMEOUT"));
        s_auth = false;
      } else {
        MG_ERROR(("AUTH FAILED"));
        s_auth = false;
      }
    } else if (event_type == 3 && status != 6) {  // Auth (not unsolicited)
      if (status == 0) {                          // Success
        s_auth = true;
      } else {
        MG_ERROR(("AUTH TIMEOUT"));
        s_auth = false;
      }
    } else if (event_type == 1) {  // Join
      if (status == 0) {           // Success
        s_join = true;
      } else {
        MG_ERROR(("%s", status == 3 /* No networks */ ? "SSID NOT FOUND"
                                                      : "JOIN FAILED"));
        s_join = false;
        mg_tcpip_call(s_ifp, MG_TCPIP_EV_WIFI_CONNECT_ERR, &status);
      }
    } else if (event_type == 12 || event_type == 5) {  // Disassoc, Deauth
      s_auth = false;
    } else if (event_type == 69) {  // Scan result
      struct scan_result *data = (struct scan_result *) (&msg->event + 1);
      size_t dlen = mg_ntohl(msg->event.datalen);
      if (dlen > len - ((uint8_t *) data - (uint8_t *) bdc)) return;
      cyw_handle_scan_result(status, data, dlen);
    }
  }  // else silently discard
}

static bool cyw_ioctl_get_(unsigned int ifc, unsigned int cmd, void *data,
                           size_t len);
static bool cyw_ioctl_set_(unsigned int ifc, unsigned int cmd, void *data,
                           size_t len);
static bool cyw_ioctl_iovar_get_(unsigned int ifc, char *var, void *data,
                                 size_t len);
static bool cyw_ioctl_iovar_set_(unsigned int ifc, char *var, void *data,
                                 size_t len);
// clang-format off
// convenience: ioctl funcs on default ifc (0), as only AP needs ifc 1
static bool cyw_ioctl_get(unsigned int cmd, void *data, size_t len) { return cyw_ioctl_get_(0, cmd, data, len); }
static bool cyw_ioctl_set(unsigned int cmd, void *data, size_t len) { return cyw_ioctl_set_(0, cmd, data, len); }
static bool cyw_ioctl_iovar_get(char *var, void *data, size_t len) { return cyw_ioctl_iovar_get_(0, var, data, len); }
static bool cyw_ioctl_iovar_set(char *var, void *data, size_t len) { return cyw_ioctl_iovar_set_(0, var, data, len); }
// clang-format on

// Wi-Fi network stuff

// clang-format off
static bool cyw_wifi_connect(char *ssid, char *pass) {
  uint32_t sup_wpa[2] = {0, 1}; // bss index 0 = STA, not open
  static const uint32_t const eapver[2] = {0, (uint32_t) -1}, // accept AP version
                              tmo[2] = {0, 2500};
  uint32_t data[64/4 + 1]; // max pass length: 64 for WPA, 128 for WPA3 SAE
  unsigned int len;
  uint32_t val; 
  val = 4; // security type: 0 for none, 2 for WPA, 4 for WPA2/WPA3, 6 for mixed WPA/WPA2
  // sup_wpa[1] = 0 if not using security
  if (!(cyw_ioctl_set(134 /* SET_WSEC */, (uint8_t *)&val, sizeof(val))
        && cyw_ioctl_iovar_set("bsscfg:sup_wpa", (void *)sup_wpa, sizeof(sup_wpa))
        && cyw_ioctl_iovar_set("bsscfg:sup_wpa2_eapver", (void *)eapver, sizeof(eapver))
        && cyw_ioctl_iovar_set("bsscfg:sup_wpa_tmo", (void *)tmo, sizeof(tmo)))
     ) return false;
  mg_delayms(2); // allow radio firmware to be ready
  // skip if not using auth
  memset(data, 0, sizeof(data));
  len = strlen(pass);
  ((uint16_t *)data)[0] = (uint16_t) len;
  ((uint16_t *)data)[1] = 1; // indicates wireless security key, skip for WPA3 SAE
  memcpy((uint8_t *)data + 2 * sizeof(uint16_t), pass, len); // skip for WPA3 SAE
  if (!cyw_ioctl_set(268 /* SET_WSEC_PMK */, data, sizeof(data))) return false; // skip for WPA3 SAE, sizeof/2 if supporting SAE but using WPA
  // for WPA3 SAE: memcpy((uint8_t *)data + sizeof(uint16_t), pass, len); cyw_ioctl_iovar_set("sae_password", data, sizeof(data));
  // resume if not using auth
  val = 1; if (!cyw_ioctl_set(20 /* SET_INFRA */, (uint8_t *)&val, sizeof(val))) return false;
  val = 0; // auth type: 0 for open, 3 for SAE
  if (!cyw_ioctl_set(22 /* SET_AUTH */, (uint8_t *)&val, sizeof(val))) return false;
  val = 1; // MFP capable: 1 for yes, 0 for no; recommended to be set for WPA2+ (2 for 'required', WPA3)
  cyw_ioctl_iovar_set("mfp", (uint8_t *)&val, sizeof(val)); // Old chipsets do not support MFP
  val = 0x80; // auth type: 0 for none, 4 for WPA PSK, 0x80 for WPA2 PSK, 0x40000 for WPA3 SAE PSK
  if (!cyw_ioctl_set(165 /* SET_WPA_AUTH */, (uint8_t *)&val, sizeof(val))) return false;
  len = strlen(ssid);
  data[0] = (uint32_t) len;
  memcpy((uint8_t *)&data[1], ssid, len);
  if (!cyw_ioctl_set(26 /* SET_SSID */, data, len + sizeof(uint32_t))) return false;
  return true;
}

static bool cyw_wifi_disconnect(void) {
  return cyw_ioctl_set(52 /* DISASSOC */, NULL, 0);
}

// For AP functions, we use explicit ifc selection; both for clarity and maintenance, as some actions are performed on ifc 0, with or without a bss_index, and others are performed on ifc 1

static bool cyw_wifi_ap_start(char *ssid, char *pass, unsigned int channel) {
  uint32_t data[64/4 + 2]; // max pass length: 64 for WPA, 128 for WPA3 SAE
  unsigned int len;
  uint32_t val; 
  // CHIP DEPENDENCY
  // RPi set the AMPDU parameter for AP (window size = 2) *****************
  // val = 2 ; cyw_ioctl_iovar_set_(0, "ampdu_ba_wsize", (uint8_t *)&val, sizeof(val));
  // some chips might require to turn APSTA off and issue a SET_AP IOCTL
  len = strlen(ssid);
  data[0] = 1; // bss index 1 = AP
  data[1] = (uint32_t) len;
  memcpy((uint8_t *)&data[2], ssid, len);
  // TODO(scaprile): this takes some time to process, or requires a delay before doing it
  if (!cyw_ioctl_iovar_set_(0, "bsscfg:ssid", (uint8_t *)&data, len + 2 * sizeof(uint32_t))) return false;
  // TODO(scaprile): but sometimes this one takes some time to process
  val = (uint32_t) channel; if (!cyw_ioctl_set_(0, 30 /* SET_CHANNEL */, (uint8_t *)&val, sizeof(val))) return false;
  data[0] = 1; // bss index 1 = AP
  data[1] = 0x00400004; // security type: 0 for none, 0x00200002 for WPA, 0x00400004 for WPA2, 0x01000004 for WPA3, 0x01400004 for mixed WPA2/WPA3, 0x00400006 for mixed WPA/WPA2
  // NOTE(): WHD writes & 0xFF if WPS is not enabled (?)
  if (!cyw_ioctl_iovar_set_(0, "bsscfg:wsec", (uint8_t *)&data, 2 * sizeof(uint32_t))) return false;
  val = 1; // MFP capable: 1 for yes, 0 for no; recommended to be set for WPA2+ (2 for 'required', WPA3)
  cyw_ioctl_iovar_set_(1, "mfp", (uint8_t *)&val, sizeof(val)); // Old chipsets do not support MFP
  mg_delayms(2); // allow radio firmware to be ready
  // skip if not using auth
  // WPA, WPA2, mixed WPA/WPA2, mixed WPA2/WPA3
  // NOTE(): WHD does not set SAE password for shared WPA2/WPA3, same do we
  memset(data, 0, sizeof(data));
  len = strlen(pass);
  ((uint16_t *)data)[0] = (uint16_t) len; // skip for WPA3 SAE
  ((uint16_t *)data)[1] = 1; // indicates wireless security key, skip for WPA3 SAE
  memcpy((uint8_t *)data + 2 * sizeof(uint16_t), pass, len); // skip for WPA3 SAE
  if (!cyw_ioctl_set_(1, 268 /* SET_WSEC_PMK */, data, sizeof(data))) return false; // skip for WPA3 SAE, sizeof/2 if supporting SAE but using WPA
  /* for WPA3 SAE: 
    memcpy((uint8_t *)data + sizeof(uint16_t), pass, len);
    cyw_ioctl_iovar_set_(1, "sae_password", data, sizeof(data)); */
  /* for WPA3 or mixed WPA2/WPA3: 
    val = 5 ; cyw_ioctl_iovar_set_(1, "sae_max_pwe_loop", (uint8_t *)&val, sizeof(val));  // Some chipsets do not support this */
  // resume if not using auth

  data[0] = 1; // bss index 1 = AP
  data[1] = 0x80; // auth type: 0 for none, 4 for WPA PSK, 0x80 for WPA2 PSK, 0x40000 for WPA3 SAE PSK; ored if mixed
  if (!cyw_ioctl_iovar_set_(0, "bsscfg:wpa_auth", (uint8_t *)&data, 2 * sizeof(uint32_t))) return false;

  val = 1 /* auto */; if (!cyw_ioctl_set_(1, 110 /* SET_GMODE */, (uint8_t *)&val, sizeof(val))) return false;
  // Set multicast tx rate to 11Mbps, may fail in some chipsets, we are enforcing it
  val = 11000000 / 500000; if (!cyw_ioctl_iovar_set_(1, "2g_mrate", (uint8_t *)&val, sizeof(val))) return false;
  val = 1; if (!cyw_ioctl_set_(1, 78 /* SET_DTIMPRD */, (uint8_t *)&val, sizeof(val))) return false;
  data[0] = 1; // bss index 1 = AP
  data[1] = 1; // UP
  // TODO(scaprile): this takes a long time to process
  if (!cyw_ioctl_iovar_set_(0, "bss", (uint8_t *)&data, 2 * sizeof(uint32_t))) return false;
  return true;
}

static bool cyw_wifi_ap_stop(void) {
  uint32_t data[2];
  data[0] = 1; // bss index 1 = AP
  data[1] = 0; // DOWN
  if (!cyw_ioctl_iovar_set_(0, "bss", (uint8_t *)&data, 2 * sizeof(uint32_t))) return false;
  // DO WE NEED TO CLEAR CHANNEL ???
  // CHIP DEPENDENCY
  //val = 8 ; cyw_ioctl_iovar_set_(0, "ampdu_ba_wsize", (uint8_t *)&val, sizeof(val));
  return true;
}

// WLAN scan handling

#pragma pack(push, 1)
// in little endian

struct wifi_scan_opt {
    uint32_t version;
    uint16_t action;
    uint16_t _;
    uint32_t ssid_len;
    uint8_t ssid[32];
    uint8_t bssid[6];
    int8_t bss_type;
    int8_t scan_type;
    int32_t nprobes;
    int32_t active_time;
    int32_t passive_time;
    int32_t home_time;
    int32_t channel_num;
    uint16_t channel_list[1];
};
#pragma pack(pop)

static bool cyw_wifi_scan(void) {
  struct wifi_scan_opt opts;
  memset(&opts, 0, sizeof(opts));
  opts.version = 1;
  opts.action = 1; // start
  opts._ = 0;
  memset(opts.bssid, 0xff, sizeof(opts.bssid));
  opts.bss_type = 2; // any
  opts.nprobes = -1;
  opts.active_time = -1;
  opts.passive_time = -1;
  opts.home_time = -1;
  opts.channel_num = 0;
  opts.channel_list[0] = 0;
  return cyw_ioctl_iovar_set("escan", (uint8_t *)&opts, sizeof(opts));
}


#pragma pack(push, 1)
// in little endian

struct scan_bss {
    uint32_t version;              // version field
    uint32_t length;               // byte length of data in this record, starting at version and including IEs
    uint8_t BSSID[6];              // Unique 6-byte MAC address
    uint16_t beacon_period;        // Interval between two consecutive beacon frames. Units are Kusec
    uint16_t capability;           // Capability information
    uint8_t SSID_len;              // SSID length
    uint8_t SSID[32];              // Array to store SSID
    uint8_t reserved1[1];          // Reserved(padding)
    uint32_t rateset_count;        // Count of rates in this set
    uint8_t rateset_rates[16];     // rates in 500kbps units, higher bit set if basic
    uint16_t chanspec;             // Channel specification for basic service set
    uint16_t atim_window;          // Announcement traffic indication message window size. Units are Kusec
    uint8_t dtim_period;           // Delivery traffic indication message period
    uint8_t reserved2[1];          // Reserved(padding)
    int16_t RSSI;                  // receive signal strength (in dBm)
    int8_t phy_noise;              // noise (in dBm)
    uint8_t n_cap;                 // BSS is 802.11n Capable
    uint8_t reserved3[2];          // Reserved(padding)
    uint32_t nbss_cap;             // 802.11n BSS Capabilities (based on HT_CAP_*)
    uint8_t ctl_ch;                // 802.11n BSS control channel number
    uint8_t reserved4[3];          // Reserved(padding)
    uint32_t reserved32[1];        // Reserved for expansion of BSS properties
    uint8_t flags;                 // flags
    uint8_t vht_cap;               // BSS is vht capable
    uint8_t reserved5[2];          // Reserved(padding)
    uint8_t basic_mcs[16];         // 802.11N BSS required MCS set
    uint16_t ie_offset;            // offset at which IEs start, from beginning
    uint16_t reserved16[1];        // Reserved(padding)
    uint32_t ie_length;            // byte length of Information Elements
    int16_t SNR;                   // Average SNR during frame reception
};

struct scan_result {
    uint32_t buflen;
    uint32_t version;
    uint16_t sync_id;
    uint16_t bss_count;
    struct scan_bss bss[1];
};

#pragma pack(pop)

// CHIP DEPENDENCY
#define CYW_BSS_BANDMASK 0xc000
#define CYW_BSS_BAND2G 0
//

static void cyw_handle_scan_result(uint32_t status, struct scan_result *data, size_t len) {
  MG_VERBOSE(("scan event, status: %ld", status));
  if (status == 0) { // SUCCESS
    MG_VERBOSE(("scan complete"));
    mg_tcpip_call(s_ifp, MG_TCPIP_EV_WIFI_SCAN_END, NULL);
  } else if (status == 8) { // PARTIAL
    struct mg_wifi_scan_bss_data bss;
    struct scan_bss *sbss = data->bss;
    unsigned int band = sbss->chanspec & CYW_BSS_BANDMASK;
    if (data->version != 109 || data->bss_count != 1) {
      MG_ERROR(("Unsupported: %lu %u", data->version, data->bss_count));
      return;
    }
    if (sbss->length > len - offsetof(struct scan_result, bss) || sbss->SSID_len > sizeof(sbss->SSID) || sbss->ie_offset < sizeof(*sbss) || sbss->ie_offset > (sizeof(*sbss) + sbss->ie_length) || sbss->ie_offset + sbss->ie_length > sbss->length)
      return; // silently discard malformed data
    if (!(sbss->flags & MG_BIT(2))) return; // RSSI_ONCHANNEL, ignore off-channel results
    bss.SSID = mg_str_n(sbss->SSID, sbss->SSID_len);
    bss.BSSID = sbss->BSSID;
    bss.RSSI = (int8_t)sbss->RSSI;
    bss.has_n = sbss->n_cap != 0;
    bss.channel = bss.has_n ? sbss->ctl_ch : (uint8_t)(sbss->chanspec & 0xff); // n 40MHz vs a/b/g and 20MHz
    bss.band = band & CYW_BSS_BAND2G ? MG_WIFI_BAND_2G : MG_WIFI_BAND_5G;
    bss.security = (sbss->capability & MG_BIT(4) /* CAP_PRIVACY */) ? MG_WIFI_SECURITY_WEP : MG_WIFI_SECURITY_OPEN;
    { // travel IEs (Information Elements) in search of security definitions
      const uint8_t wot1[4] = {0x00, 0x50, 0xf2, 0x01}; // WPA_OUI_TYPE1                     
      uint8_t *ie = (uint8_t *)sbss + sbss->ie_offset;
      int bytes = (int) sbss->ie_length;
      while (bytes > 0 && ie[1] + 2 < bytes) { // ie[0] -> type, ie[1] -> bytes from ie[2]
        if (ie[0] == 48 /* IE_ID_RSN */) bss.security |= MG_WIFI_SECURITY_WPA2;
        if (ie[0] == 221 /* IE_ID_VENDOR_SPECIFIC */ && memcmp(&ie[2], wot1, 4) == 0)
          bss.security |= MG_WIFI_SECURITY_WPA;
        ie += ie[1] + 2;
        bytes -= ie[1] + 2;
      }
    }
    MG_VERBOSE(("BSS: %.*s (%u) (%M) %d dBm %u", bss.SSID.len, bss.SSID.buf, bss.channel, mg_print_mac, bss.BSSID, (int) bss.RSSI, bss.security));  
    mg_tcpip_call(s_ifp, MG_TCPIP_EV_WIFI_SCAN_RESULT, &bss);
  } else {
    MG_ERROR(("scan error"));
  } 
}
// clang-format on

// IOCTL stuff. All values read and written are in little endian format

static uint16_t s_ioctl_reqid;

// CDC handler for waiting loop
static uint8_t *s_ioctl_resp;
static bool s_ioctl_err;

static void cyw_handle_cdc(struct cdc_hdr *cdc, size_t len) {
  uint8_t *resp = (uint8_t *) cdc + sizeof(*cdc);
  MG_VERBOSE(("%u bytes CDC frame", len));
  if ((cdc->flags >> 16) != s_ioctl_reqid) return;
  if (cdc->flags & 1) {
    MG_ERROR(("IOCTL error: %ld", -cdc->status));
    s_ioctl_err = true;
    return;
  }
  if (mg_log_level >= MG_LL_VERBOSE) mg_hexdump((void *) cdc, len);
  MG_DEBUG(("IOCTL result: %02x %02x %02x %02x ...", resp[0], resp[1], resp[2],
            resp[3]));
  s_ioctl_resp = resp;
}
// NOTE(): alt no loop handler dispatching IOCTL response to current handler:
// static void *s_ioctl_hnd; *s_ioctl_hnd(ioctl, len);
// app is a state machine calling get/sets and advancing via these callbacks

#pragma pack(push, 1)
// all little endian

struct ctrl_hdr {
  struct sdpcm_hdr sdpcm;
  struct cdc_hdr cdc;
};

#pragma pack(pop)

// IOCTL command send
static void cyw_ioctl_send_cmd(unsigned int ifc, unsigned int cmd, bool set,
                               size_t len) {
  struct ctrl_hdr *hdr = (struct ctrl_hdr *) txdata;
  uint16_t txlen = (uint16_t) (len + sizeof(*hdr));
  memset(txdata, 0, sizeof(*hdr));
  hdr->cdc.cmd = cmd;
  hdr->cdc.olen = (uint16_t) len;
  // hdr->cdc.ilen = 0; // actually zeroed above
  hdr->cdc.flags = ((uint32_t) ++s_ioctl_reqid << 16) | ((ifc & 0xf) << 12) |
                   (set ? MG_BIT(1) : 0);
  hdr->sdpcm.len = txlen;
  hdr->sdpcm._len = (uint16_t) ~txlen;
  hdr->sdpcm.sw_hdr.sequence = ++s_tx_seqno;
  hdr->sdpcm.sw_hdr.channel_and_flags = CYW_SDPCM_CTRL_HDR;
  hdr->sdpcm.sw_hdr.header_length = offsetof(struct ctrl_hdr, cdc);
  cyw_bus_tx(txdata, txlen);
}

// just send respective commands, response handled via CDC handler
static void cyw_ioctl_send_get(unsigned int ifc, unsigned int cmd) {
  cyw_ioctl_send_cmd(ifc, cmd, false, 0);
}

static void cyw_ioctl_send_set(unsigned int ifc, unsigned int cmd, void *data,
                               size_t len) {
  if (data != NULL && len > 0)
    memcpy((uint8_t *) txdata + sizeof(struct ctrl_hdr), data, len);
  cyw_ioctl_send_cmd(ifc, cmd, true, (uint16_t) len);
}

static void cyw_ioctl_send_iovar_get(unsigned int ifc, char *var, size_t len) {
  unsigned int namelen = strlen(var) + 1;  // include '\0'
  // cmd = GET IOVAR, "set" the name...
  cyw_ioctl_send_set(ifc, 262, var, len > namelen ? len : namelen);
}

static void cyw_ioctl_send_iovar_set2(unsigned int ifc, char *var, void *data1,
                                      size_t len1, void *data2, size_t len2) {
  struct ctrl_hdr *hdr = (struct ctrl_hdr *) txdata;
  unsigned int namelen = strlen(var) + 1;  // include '\0'
  uint16_t txlen, payload_len = (uint16_t) (namelen + len1 + len2);
  memcpy((uint8_t *) txdata + sizeof(*hdr), var, namelen);
  memcpy((uint8_t *) txdata + namelen + sizeof(*hdr), data1, len1);
  if (data2 != NULL)
    memcpy((uint8_t *) txdata + namelen + sizeof(*hdr) + len1, data2, len2);
  txlen = (uint16_t) (payload_len + sizeof(*hdr));
  cyw_ioctl_send_cmd(ifc, 263, true, txlen);  // cmd = SET IOVAR
}

static void cyw_ioctl_send_iovar_set(unsigned int ifc, char *var, void *data,
                                     size_t len) {
  cyw_ioctl_send_iovar_set2(ifc, var, data, len, NULL, 0);
}

// wait for a response, meanwhile delivering received frames and events
static bool cyw_ioctl_wait(void) {
  unsigned int times = 6000;
  s_ioctl_resp = NULL;
  s_ioctl_err = false;
  while (s_ioctl_resp == NULL && !s_ioctl_err && times-- > 0)
    cyw_poll();  // TODO(scaprile): review wait/sleep strategy (this loop is executed only when initializing/acting on the chip)
  MG_DEBUG(("resp: %lp, err: %c, times: %d", s_ioctl_resp,
            s_ioctl_err ? '1' : '0', (int) times));
  return s_ioctl_resp != NULL;
}

static bool cyw_ioctl_waitdata(void *data, size_t len) {
  if (!cyw_ioctl_wait()) return false;
  memcpy(data, s_ioctl_resp, len);
  return true;
}

// send respective commands, wait for a response or timeout
static bool cyw_ioctl_get_(unsigned int ifc, unsigned int cmd, void *data,
                           size_t len) {
  cyw_ioctl_send_get(ifc, cmd);
  return cyw_ioctl_waitdata(data, len);
}
static bool cyw_ioctl_set_(unsigned int ifc, unsigned int cmd, void *data,
                           size_t len) {
  cyw_ioctl_send_set(ifc, cmd, data, len);
  return cyw_ioctl_wait();
}

static bool cyw_ioctl_iovar_get_(unsigned int ifc, char *var, void *data,
                                 size_t len) {
  cyw_ioctl_send_iovar_get(ifc, var, len);
  return cyw_ioctl_waitdata(data, len);
}
static bool cyw_ioctl_iovar_set2_(unsigned int ifc, char *var, void *data1,
                                  size_t len1, void *data2, size_t len2) {
  cyw_ioctl_send_iovar_set2(ifc, var, data1, len1, data2, len2);
  return cyw_ioctl_wait();
}
static bool cyw_ioctl_iovar_set_(unsigned int ifc, char *var, void *data,
                                 size_t len) {
  return cyw_ioctl_iovar_set2_(ifc, var, data, len, NULL, 0);
}

// CYW43 chipset specifics. All values read and written are in little endian
// format

#pragma pack(push, 1)
// all little endian

struct cyw_country {
  uint32_t a;
  int32_t rev;
  uint32_t c;
};

struct clm_hdr {
  uint16_t flag;
  uint16_t type;
  uint32_t len;
  uint32_t crc;
};

#pragma pack(pop)

// worlwide rev0, try rev 17 for 4343W
static const uint32_t country_code = 'X' + ('X' << 8) + (0 << 16);

static bool cyw_spi_init();

// clang-format off
static bool cyw_init(struct mg_tcpip_driver_cyw_firmware *fw, uint8_t *mac) {
  uint32_t val = 0;
  if (!cyw_spi_init()) return false; // BUS DEPENDENCY
  // BT-ENABLED DEPENDENCY
  // set Wi-Fi up
  val = 0 /* disable */; cyw_ioctl_iovar_set("bus:txglom", (uint8_t *)&val, sizeof(val));
  val = 1 /* on */; cyw_ioctl_iovar_set("apsta", (uint8_t *)&val, sizeof(val));
  // CHIP DEPENDENCY
  val = 8 ; cyw_ioctl_iovar_set("ampdu_ba_wsize", (uint8_t *)&val, sizeof(val));
  val = 4 ; cyw_ioctl_iovar_set("ampdu_mpdu", (uint8_t *)&val, sizeof(val));
  val = 0 /* 8K */; cyw_ioctl_iovar_set("ampdu_rx_factor", (uint8_t *)&val, sizeof(val));  
  //
  {
    struct cyw_country c;
    unsigned int rev = (unsigned int) (country_code >> 16) & 0xffff;
    c.c = c.a = country_code & 0xffff;
    c.rev = rev == 0 ? -1 : (int32_t) rev; // if rev is 0, set it to -1, the chip will use any NVRAM/OTP configured aggregate or default to rev 0
    cyw_ioctl_iovar_set("country", (void *)&c, sizeof(c));
  } // this takes some time to process
  { // so do some retries while enabling events of interest
    // we care for SET_SSID(0), JOIN(1), AUTH(3), DEAUTH(5), DISASSOC_IND(12), LINK(16), PSK_SUP(46), SCAN_RESULT(69); all < 128
    uint32_t data[128/8/4 + 1];
    data[0] = 0; // bss index: 0 = STA
    memset(&data[1], 0, 128/8); // mark all as not desired
    data[1] = MG_BIT(0) | MG_BIT(1) | MG_BIT(3) | MG_BIT(5) | MG_BIT(12) | MG_BIT(16); // events 0 to 31
    data[2] = MG_BIT(46 - 32); // events 32 to 63
    data[3] = MG_BIT(69 - 64); // events 64 to 95
    unsigned int times = 100;
    while (times --)
      if (cyw_ioctl_iovar_set("bsscfg:event_msgs", (uint8_t *)data, sizeof(data))) break;
    if (times == ~0) return false;
  }
  val = 0; if (!cyw_ioctl_set(64 /* SET_ANTDIV */, (uint8_t *)&val, sizeof(val))) return false;
  if (!cyw_ioctl_set(2 /* UP, interface up */, NULL, 0)) return false;
  // use PM2 power saving for max throughput
  val = 200 /* ms */; if (!cyw_ioctl_iovar_set("pm2_sleep_ret", (uint8_t *)&val, sizeof(val))) return false;
  // set beacon intervals to reduce power consumption while associated to an AP but idle
  val = 1; if (!cyw_ioctl_iovar_set("bcn_li_bcn", (uint8_t *)&val, sizeof(val))) return false;
  val = 1; if (!cyw_ioctl_iovar_set("bcn_li_dtim", (uint8_t *)&val, sizeof(val))) return false;
  val = 10; if (!cyw_ioctl_iovar_set("assoc_listen", (uint8_t *)&val, sizeof(val))) return false;
  val = 1 /* auto */; if (!cyw_ioctl_set(110 /* SET_GMODE */, (uint8_t *)&val, sizeof(val))) return false;
  val = 0 /* any */; if (!cyw_ioctl_set(142 /* SET_BAND */, (uint8_t *)&val, sizeof(val))) return false;
  if (mg_log_level >= MG_LL_DEBUG) {
    char text[256]; // this is huge, but we're just starting up
    if (cyw_ioctl_iovar_get("ver", (uint8_t *)text, sizeof(text))) {
      unsigned int len = strnlen(text, sizeof(text));
      MG_DEBUG(("Firmware:\n%.*s", len, text));
    }
    text[0] = '\0';
    if (cyw_ioctl_iovar_get("clmver", (uint8_t *)text, sizeof(text)) && text[0] != '\0') {
      unsigned int len = strnlen(text, sizeof(text));
      MG_DEBUG(("CLM:\n%.*s", len, text));
    }
  }
  {
    if(cyw_ioctl_iovar_get("cur_etheraddr", mac, 6)) {
      MG_DEBUG(("MAC: %M", mg_print_mac, mac));
    } else {
      MG_ERROR(("read MAC failed"));
    }
  }
  return true;
}
// clang-format on

static bool cyw_load_fwll(void *fwdata, size_t fwlen, void *nvramdata,
                          size_t nvramlen);

static bool cyw_load_firmware(struct mg_tcpip_driver_cyw_firmware *fw) {
  return cyw_load_fwll((void *) fw->code_addr, fw->code_len,
                       (void *) fw->nvram_addr, fw->nvram_len);
}

// clang-format off
static bool cyw_load_clmll(void *data, size_t len) {
  unsigned int sent = 0, offset = 0;
  struct clm_hdr hdr = {
      .flag = 1 << 12 /* DLOAD_HANDLER_VER */ | MG_BIT(1) /* DL_BEGIN */,
      .type = 2,
      .crc = 0};
  while (sent < len) {
    unsigned int bytes = len - sent;
    if (bytes > 1024) bytes = 1024;
    if (sent + bytes >= len) hdr.flag |= MG_BIT(2);  // DL_END;
    hdr.len = bytes;
    if (!cyw_ioctl_iovar_set2_(0, "clmload", (void *) &hdr, sizeof(hdr), (uint8_t *) data + offset, bytes))
      break;
    sent += bytes;
    offset += bytes;
    hdr.flag &= ~MG_BIT(1);  // DL_BEGIN
  }
  return sent >= len;
}
// clang-format on

static bool cyw_load_clm(struct mg_tcpip_driver_cyw_firmware *fw) {
  return cyw_load_clmll((void *) fw->clm_addr, fw->clm_len);
}

// CYW43 chip backplane specifics. All values read and written are in little
// endian format

// Access to chip backplane is done windowed in 32KB banks
// - addr = area base address + register offset
// - set the window address to addr & ~ADDRMSK
// - access addr & ADDRMSK for non-32-bit quantities
// - if accesing 32-bit quantities, do it on (addr & ADDRMSK) | ACCSS4B
#define CYW_CHIP_CHIPCOMMON 0x18000000
#define CYW_CHIP_BCKPLN_WINSZ 0x8000
#define CYW_CHIP_BCKPLN_ADDRMSK 0x7fff
#define CYW_CHIP_BCKPLN_ACCSS4B MG_BIT(15)
#define CYW_CHIP_BCKPLN_WRAPPOFF 0x100000
#define CYW_CHIP_BCKPLN_SPIMAX 64
#define CYW_CHIP_BCKPLN_SDIOMAX 1536

// CHIP DEPENDENCY
#define CYW_CHIP_ARMCORE_BASE (CYW_CHIP_CHIPCOMMON + 0x3000)
#define CYW_CHIP_SOCSRAM_BASE (CYW_CHIP_CHIPCOMMON + 0x4000)
#define CYW_CHIP_ARMCORE (CYW_CHIP_ARMCORE_BASE + CYW_CHIP_BCKPLN_WRAPPOFF)
#define CYW_CHIP_SOCSRAM (CYW_CHIP_SOCSRAM_BASE + CYW_CHIP_BCKPLN_WRAPPOFF)
#define CYW_CHIP_ATCMRAM_BASE 0
#define CYW_CHIP_RAM_SIZE 0x80000
//

#define CYW_CHIP_ADDRLOW 0x1000a
#define CYW_CHIP_ADDRMID 0x1000b
#define CYW_CHIP_ADDRHIGH 0x1000c
#define CYW_CHIP_SPIFRCTRL 0x1000d
#define CYW_CHIP_CLOCKCSR 0x1000e
#define CYW_CHIP_PULLUP 0x1000f
#define CYW_CHIP_WAKEUPCTL 0x1001e
#define CYW_CHIP_SLEEPCSR 0x1001f

#define CYW_CHIP_SOCSRAM_BANKXIDX 0x010
#define CYW_CHIP_SOCSRAM_BANKXPDA 0x044
#define CYW_CHIP_AI_IOCTRL 0x408
#define CYW_CHIP_AI_RESETCTRL 0x800

static bool cyw_spi_write(unsigned int f, uint32_t addr, void *data,
                          uint16_t len);
static void cyw_spi_read(unsigned int f, uint32_t addr, void *data,
                         uint16_t len);

// clang-format off
// set backplane window to requested area.
static void cyw_set_backplane_window(uint32_t addr) {
  uint32_t val;
  addr &= ~CYW_CHIP_BCKPLN_ADDRMSK;
  val = (addr >> 24) & 0xff; cyw_spi_write(CYW_SD_FUNC_CHIP, CYW_CHIP_ADDRHIGH, &val, 1);
  val = (addr >> 16) & 0xff; cyw_spi_write(CYW_SD_FUNC_CHIP, CYW_CHIP_ADDRMID, &val, 1);
  val = (addr >> 8) & 0xff; cyw_spi_write(CYW_SD_FUNC_CHIP, CYW_CHIP_ADDRLOW, &val, 1);
}

static bool cyw_core_reset(uint32_t core_base, bool check) {
  uint32_t val = 0;
  // core disabled after chip reset
  cyw_set_backplane_window(core_base); // set backplane window for requested area; we do know offsets fall within that window
  // possible CHIP DEPENDENCY: AI_RESETSTATUS check and wait (instead of these cool reads) to ensure backplane operations end
  cyw_spi_read(CYW_SD_FUNC_CHIP, (core_base + CYW_CHIP_AI_IOCTRL) & CYW_CHIP_BCKPLN_ADDRMSK, &val, 1); // ensure backplane operations end
  val = MG_BIT(1) | MG_BIT(0) /* SICF_FGC | SICF_CLOCK_EN */; cyw_spi_write(CYW_SD_FUNC_CHIP, (core_base + CYW_CHIP_AI_IOCTRL) & CYW_CHIP_BCKPLN_ADDRMSK, &val, 1); // reset
  cyw_spi_read(CYW_SD_FUNC_CHIP, (core_base + CYW_CHIP_AI_IOCTRL) & CYW_CHIP_BCKPLN_ADDRMSK, &val, 1); // ensure backplane operations end
  val = 0x00; cyw_spi_write(CYW_SD_FUNC_CHIP, (core_base + CYW_CHIP_AI_RESETCTRL) & CYW_CHIP_BCKPLN_ADDRMSK, &val, 1); // release reset
  mg_delayms(1);
  val = MG_BIT(0) /* SICF_CLOCK_EN */; cyw_spi_write(CYW_SD_FUNC_CHIP, (core_base + CYW_CHIP_AI_IOCTRL) & CYW_CHIP_BCKPLN_ADDRMSK, &val, 1);
  cyw_spi_read(CYW_SD_FUNC_CHIP, (core_base + CYW_CHIP_AI_IOCTRL) & CYW_CHIP_BCKPLN_ADDRMSK, &val, 1); // ensure backplane operations end
  mg_delayms(1);

  if (check) {
    // Verify only clock is enabled
    cyw_spi_read(CYW_SD_FUNC_CHIP, (core_base + CYW_CHIP_AI_IOCTRL) & CYW_CHIP_BCKPLN_ADDRMSK, &val, 1);
    if ((val & (MG_BIT(1) | MG_BIT(0)) /* SICF_FGC | SICF_CLOCK_EN) */) != MG_BIT(0)) return false;
    // Verify it is not in reset state
    cyw_spi_read(CYW_SD_FUNC_CHIP, (core_base + CYW_CHIP_AI_RESETCTRL) & CYW_CHIP_BCKPLN_ADDRMSK, &val, 1);
    if (val & MG_BIT(0)) return false; // AIRC_RESET
  }
  return true;
}

static void cyw_socram_init(void) {
  uint32_t val;
  // CHIP DEPENDENCY: disable remap for SRAM_3
  cyw_set_backplane_window(CYW_CHIP_SOCSRAM_BASE); // set backplane window for requested area; we do know offsets fall within that window
  val = 0x03; cyw_spi_write(CYW_SD_FUNC_CHIP, ((CYW_CHIP_SOCSRAM_BASE + CYW_CHIP_SOCSRAM_BANKXIDX) & CYW_CHIP_BCKPLN_ADDRMSK) | CYW_CHIP_BCKPLN_ACCSS4B, &val, sizeof(val));
  val = 0x00; cyw_spi_write(CYW_SD_FUNC_CHIP, ((CYW_CHIP_SOCSRAM_BASE + CYW_CHIP_SOCSRAM_BANKXPDA) & CYW_CHIP_BCKPLN_ADDRMSK) | CYW_CHIP_BCKPLN_ACCSS4B, &val, sizeof(val));
}

// transfer is fractioned in bus-to-backplane-size units within backplane windows
static void cyw_load_data(uint32_t dest, void *data, size_t len) {
  size_t sent = 0, offset = 0;
  uint32_t last_addr = ~0;
  while (sent < len)  {
    size_t bytes = len - sent, avail;
    uint32_t addr = dest + offset;
    if (addr - last_addr >= CYW_CHIP_BCKPLN_WINSZ || last_addr == ~0) {
      cyw_set_backplane_window(addr); // set backplane window for requested area
      last_addr = addr & ~CYW_CHIP_BCKPLN_ADDRMSK;
    }
    addr &= CYW_CHIP_BCKPLN_ADDRMSK;
    avail = CYW_CHIP_BCKPLN_WINSZ - (unsigned int) addr;
    if (bytes > avail) bytes = avail;
    // BUS DEPENDENCY: max bus to backplane transfer size
    if (bytes > CYW_CHIP_BCKPLN_SPIMAX) bytes = CYW_CHIP_BCKPLN_SPIMAX;
    cyw_spi_write(CYW_SD_FUNC_CHIP, addr | CYW_CHIP_BCKPLN_ACCSS4B, (uint8_t *)data + offset, bytes);
    sent += bytes;
    offset += bytes;
  }
}

// CHIP DEPENDENCY: no SOCSRAM base address; start address in fwdata image (Cortex-R4 chips)
static bool cyw_load_fwll(void *fwdata, size_t fwlen, void *nvramdata, size_t nvramlen) {
  uint32_t val = ((~(nvramlen / 4) & 0xffff) << 16) | (nvramlen / 4); // ~len len in 32-bit words
  cyw_core_reset(CYW_CHIP_SOCSRAM, false);  // cores were disabled at chip reset
  cyw_socram_init();
  cyw_load_data(CYW_CHIP_ATCMRAM_BASE, fwdata, fwlen);
  mg_delayms(5); // ************ CHECK IF THIS IS ACTUALLY NEEDED
  // Load NVRAM and place 'length ~length' at the end; end of chip RAM
  { 
    const uint32_t start = CYW_CHIP_RAM_SIZE - 4 - nvramlen;
    cyw_load_data(start, nvramdata, nvramlen); // nvramlen must be a multiple of 4
    // RAM_SIZE is a multiple of WINSZ, so the place for len ~len will be at the end of the window
    cyw_spi_write(CYW_SD_FUNC_CHIP, (CYW_CHIP_BCKPLN_WINSZ - 4) | CYW_CHIP_BCKPLN_ACCSS4B, &val, sizeof(val));
  }
  // Reset ARM core and check it starts
  if (!cyw_core_reset(CYW_CHIP_ARMCORE, true)) return false;
  return true;
}
// clang-format on

// CYW43 SPI bus specifics

#define CYW_BUS_SPI_BUSCTRL 0x00     // 4 regs, 0 to 3
#define CYW_BUS_SPI_INT 0x04         // 2 regs, 4 to 5
#define CYW_BUS_SPI_INTEN 0x06       // 16-bit register
#define CYW_BUS_SPI_STATUS 0x08      // 32-bit register
#define CYW_BUS_SPI_TEST 0x14        // 32-bit register
#define CYW_BUS_SPI_RESPDLY_F1 0x1d  // 8-bit register, F1: chip

#define CYW_BUS_STS_LEN(x) ((x >> 9) & 0x7ff)

// clang-format off
static size_t cyw_spi_poll(uint8_t *response) {
  size_t len;
  uint32_t res;
  // SPI poll
  cyw_spi_read(CYW_SD_FUNC_BUS, CYW_BUS_SPI_STATUS, &res, sizeof(res));
  if (res == ~0 || !(res & MG_BIT(8) /* packet available */ )) return 0;
  len = CYW_BUS_STS_LEN(res);
  if (len == 0) { // just ack IRQ
    uint16_t val = 1;
    cyw_spi_write(CYW_SD_FUNC_CHIP, CYW_CHIP_SPIFRCTRL, &val, 1);
    cyw_spi_read(CYW_SD_FUNC_BUS, CYW_BUS_SPI_INT, &val, sizeof(val));
    cyw_spi_write(CYW_SD_FUNC_BUS, CYW_BUS_SPI_INT, &val, sizeof(val));
    return 0;
  }
  cyw_spi_read(CYW_SD_FUNC_WLAN, 0,  response, len);
  return len;
}

// BUS DEPENDENCY: name is generic but function is bus dependent
static size_t cyw_bus_tx(uint32_t *data, uint16_t len) {
  while (len & 3) data[len++] = 0; // SPI 32-bit padding (SDIO->64-byte)
  return cyw_spi_write(CYW_SD_FUNC_WLAN, 0, data, len) ? len: 0;
}

// this can be integrated in lowest level SPI read/write _driver_ functions
// (those calling hal SPI transaction functions), though is only used at start
uint32_t sw16_2(uint32_t data) {
  return ((uint32_t)mg_htons((uint16_t)(data >> 16)) << 16) + mg_htons((uint16_t)data);
}

// DS 4.2.2 Table 6: signal we're working in 16-bit mode
#define CYW_SD_16bMODE MG_BIT(2) // arbitrary bit out of the FUNC space

static bool cyw_spi_init() {
  struct mg_tcpip_driver_cyw_data *d =
      (struct mg_tcpip_driver_cyw_data *) s_ifp->driver_data;
  uint32_t val = 0;
  // DS 4.2.3 Boot-Up Sequence; WHD: other chips might require more effort
  unsigned int times = 51;
  while (times--) {
    cyw_spi_read(CYW_SD_FUNC_BUS | CYW_SD_16bMODE, CYW_BUS_SPI_TEST, &val, sizeof(val));
    if (sw16_2(val) == 0xFEEDBEAD) break;
    mg_delayms(1);
  }
  if (times == ~0) return false;
  // DS 4.2.3 Table 6. Chip starts in 16-bit little-endian mode.
  // Configure SPI and switch to 32-bit big-endian mode:
  // - High-speed mode
  // - IRQ POLARITY high
  // - SPI RESPONSE DELAY 4 bytes time [not in DS] TODO(scaprile): logic ana
  // - Status not sent after command, IRQ with status
  val = sw16_2(0x000204b3); // 4 reg content
  cyw_spi_write(CYW_SD_FUNC_BUS | CYW_SD_16bMODE, CYW_BUS_SPI_BUSCTRL, &val, sizeof(val));
  cyw_spi_read(CYW_SD_FUNC_BUS, CYW_BUS_SPI_TEST, &val, sizeof(val));
  if (val != 0xFEEDBEAD) return false;
  val = 4; cyw_spi_write(CYW_SD_FUNC_BUS, CYW_BUS_SPI_RESPDLY_F1, &val, 1);
  val = 0x99; // clear error bits DATA_UNAVAILABLE, COMMAND_ERROR, DATA_ERROR, F1_OVERFLOW
  cyw_spi_write(CYW_SD_FUNC_BUS, CYW_BUS_SPI_INT, &val, 1);
  val = 0x00be; // Enable IRQs F2_F3_FIFO_RD_UNDERFLOW, F2_F3_FIFO_WR_OVERFLOW, COMMAND_ERROR, DATA_ERROR, F2_PACKET_AVAILABLE, F1_OVERFLOW
  // BT-ENABLED DEPENDENCY: add F1_INTR (bit 13)
  cyw_spi_write(CYW_SD_FUNC_BUS, CYW_BUS_SPI_INTEN, &val, sizeof(uint16_t));

  // chip backplane is ready, initialize it
  // request ALP (Active Low Power) clock
  val = MG_BIT(3) /* ALP_REQ */; cyw_spi_write(CYW_SD_FUNC_CHIP, CYW_CHIP_CLOCKCSR, &val, 1);
  // BT-ENABLED DEPENDENCY
  times = 10;
  while (times--) {
    cyw_spi_read(CYW_SD_FUNC_CHIP, CYW_CHIP_CLOCKCSR, &val, 1);
    if (val & MG_BIT(6)) break; // ALP_AVAIL
    mg_delayms(1);
  }
  if (times == ~0) return false;
  // clear request
  val = 0; cyw_spi_write(CYW_SD_FUNC_CHIP, CYW_CHIP_CLOCKCSR, &val, 1);
  cyw_set_backplane_window(CYW_CHIP_CHIPCOMMON); // set backplane window to start of CHIPCOMMON area
  cyw_spi_read(CYW_SD_FUNC_CHIP, (CYW_CHIP_CHIPCOMMON + 0x00) & CYW_CHIP_BCKPLN_ADDRMSK, &val, 2);
  MG_INFO(("WLAN chip is CYW%u", *((uint16_t *)&val)));

  // Load firmware (code and NVRAM)
  if (!cyw_load_firmware(d->fw)) return false;

  // Wait for High Throughput (HT) clock ready
  times = 50;
  while (times--) {
    cyw_spi_read(CYW_SD_FUNC_CHIP, CYW_CHIP_CLOCKCSR, &val, 1);
    if (val & MG_BIT(7)) break; // HT_AVAIL
    mg_delayms(1);
  }
  if (times == ~0) return false;
  // Wait for backplane ready
  times = 1000;
  while (times--) {
    cyw_spi_read(CYW_SD_FUNC_BUS, CYW_BUS_SPI_STATUS, &val, sizeof(val));
    if (val & MG_BIT(5)) break; // F2_RX_READY
    mg_delayms(1);
  }
  if (times == ~0) return false;

  // CHIP DEPENDENCY
  // Enable save / restore
  // Configure WakeupCtrl, set HT_AVAIL in CLOCK_CSR
  cyw_spi_read(CYW_SD_FUNC_CHIP, CYW_CHIP_WAKEUPCTL, &val, 1);
  val |= MG_BIT(1) /* WAKE_TILL_HT_AVAIL */; cyw_spi_write(CYW_SD_FUNC_CHIP, CYW_CHIP_WAKEUPCTL, &val, 1);
#if 0
  // Set BRCM_CARDCAP to CMD_NODEC. NOTE(): This is probably only necessary for SDIO, not SPI
  val = MG_BIT(3); cyw_spi_write(CYW_SD_FUNC_BUS, 0xf0 /* SDIOD_CCCR_BRCM_CARDCAP */, &val, 1);
#endif
  // Force HT request to chip backplane
  val = MG_BIT(1) /* FORCE_HT */; cyw_spi_write(CYW_SD_FUNC_CHIP, CYW_CHIP_CLOCKCSR, &val, 1);
  // Enable Keep SDIO On (KSO)
  cyw_spi_read(CYW_SD_FUNC_CHIP, CYW_CHIP_SLEEPCSR, &val, 1);
  if (!(val & MG_BIT(0))) {
      val |= MG_BIT(0); cyw_spi_write(CYW_SD_FUNC_CHIP, CYW_CHIP_SLEEPCSR, &val, 1);
  }
  // The SPI bus can be configured for sleep (KSO controls wlan block sleep)
  cyw_spi_read(CYW_SD_FUNC_BUS, CYW_BUS_SPI_BUSCTRL, &val, sizeof(val));
  val &= ~MG_BIT(7) /* WAKE_UP */; cyw_spi_write(CYW_SD_FUNC_BUS, CYW_BUS_SPI_BUSCTRL, &val, sizeof(val));
  // Set SPI bus sleep
  val = 0x0f; cyw_spi_write(CYW_SD_FUNC_CHIP, CYW_CHIP_PULLUP, &val, 1);

  // Clear pullups. NOTE(): ?
  val = 0x00; cyw_spi_write(CYW_SD_FUNC_CHIP, CYW_CHIP_PULLUP, &val, 1);
  cyw_spi_read(CYW_SD_FUNC_CHIP, CYW_CHIP_PULLUP, &val, 1);
  // Clear possible data unavailable error
  cyw_spi_read(CYW_SD_FUNC_BUS, CYW_BUS_SPI_INTEN, &val, sizeof(uint16_t));
  if (val & MG_BIT(0)) cyw_spi_write(CYW_SD_FUNC_BUS, CYW_BUS_SPI_INTEN, &val, sizeof(uint16_t));

  // Load CLM blob
  if (!cyw_load_clm(d->fw)) return false;

  return true;
}
// clang-format on

// gSPI, DS 4.2.1 Fig.12
#define CYW_SD_LEN(x) ((x) &0x7FF)             // bits 0-10
#define CYW_SD_ADDR(x) (((x) &0x1FFFF) << 11)  // bits 11-27,
#define CYW_SD_FUNC(x) (((x) &3) << 28)        // bits 28-29
#define CYW_SD_INC MG_BIT(30)
#define CYW_SD_WR MG_BIT(31)

static bool cyw_spi_write(unsigned int f, uint32_t addr, void *data,
                          uint16_t len) {
  struct mg_tcpip_driver_cyw_data *d =
      (struct mg_tcpip_driver_cyw_data *) s_ifp->driver_data;
  struct mg_tcpip_spi_ *s = (struct mg_tcpip_spi_ *) d->spi;
  uint32_t hdr = CYW_SD_WR | CYW_SD_INC | CYW_SD_FUNC(f) | CYW_SD_ADDR(addr) |
                 CYW_SD_LEN(len);  // gSPI header
  // TODO(scaprile): check spin in between and timeout values, return false
  if (f == CYW_SD_FUNC_WLAN) {
    uint32_t val = 0;
    while ((val & MG_BIT(5)) != MG_BIT(5))  // F2 rx ready (FIFO ready)
      cyw_spi_read(CYW_SD_FUNC_BUS, CYW_BUS_SPI_STATUS, &val, sizeof(val));
  }
  if (f & CYW_SD_16bMODE)
    hdr = sw16_2(hdr);  // swap half-words in 16-bit little-endian mode

  s->begin(NULL);
  s->txn(NULL, (uint8_t *) &hdr, NULL, sizeof(hdr));
  if (len <= 4) {
    uint32_t pad = 0;
    memcpy(&pad, data, len);
    s->txn(NULL, (uint8_t *) &pad, NULL, sizeof(pad));
  } else {
    s->txn(NULL, (uint8_t *) data, NULL, len);
  }
  s->end(NULL);
  return true;
}

// will write 32-bit aligned quantities to data if f == CYW_SD_FUNC_WLAN
static void cyw_spi_read(unsigned int f, uint32_t addr, void *data,
                         uint16_t len) {
  struct mg_tcpip_driver_cyw_data *d =
      (struct mg_tcpip_driver_cyw_data *) s_ifp->driver_data;
  struct mg_tcpip_spi_ *s = (struct mg_tcpip_spi_ *) d->spi;
  uint32_t padding =
      f == CYW_SD_FUNC_CHIP
          ? 4
          : 0;  // add padding to chip backplane reads as a response delay
  uint32_t hdr = CYW_SD_INC | CYW_SD_FUNC(f) | CYW_SD_ADDR(addr) |
                 CYW_SD_LEN(len + padding);  // gSPI header
  if (f == CYW_SD_FUNC_WLAN && (len & 3))
    len = (len + 4) & ~3;  // align WLAN transfers to 32-bit
  if (f & CYW_SD_16bMODE)
    hdr = sw16_2(hdr);  // swap half-words in 16-bit little-endian mode

  s->begin(NULL);
  s->txn(NULL, (uint8_t *) &hdr, NULL, sizeof(hdr));
  if (f == CYW_SD_FUNC_CHIP) {
    uint32_t pad;
    s->txn(NULL, NULL, (uint8_t *) &pad, 4);  // read padding back and discard
  }
  s->txn(NULL, NULL, (uint8_t *) data, len);
  s->end(NULL);
}

// Mongoose Wi-Fi API functions

bool mg_wifi_scan(void) {
  return cyw_wifi_scan();
}

bool mg_wifi_connect(char *ssid, char *pass) {
  return cyw_wifi_connect(ssid, pass);
}

bool mg_wifi_disconnect(void) {
  return cyw_wifi_disconnect();
}

bool mg_wifi_ap_start(char *ssid, char *pass, unsigned int channel) {
  return cyw_wifi_ap_start(ssid, pass, channel);
}

bool mg_wifi_ap_stop(void) {
  return cyw_wifi_ap_stop();
}

#endif

#ifdef MG_ENABLE_LINES
#line 1 "src/drivers/imxrt.c"
#endif


#if MG_ENABLE_TCPIP && defined(MG_ENABLE_DRIVER_IMXRT) && MG_ENABLE_DRIVER_IMXRT
struct imxrt_enet {
  volatile uint32_t RESERVED0, EIR, EIMR, RESERVED1, RDAR, TDAR, RESERVED2[3],
      ECR, RESERVED3[6], MMFR, MSCR, RESERVED4[7], MIBC, RESERVED5[7], RCR,
      RESERVED6[15], TCR, RESERVED7[7], PALR, PAUR, OPD, TXIC0, TXIC1, TXIC2,
      RESERVED8, RXIC0, RXIC1, RXIC2, RESERVED9[3], IAUR, IALR, GAUR, GALR,
      RESERVED10[7], TFWR, RESERVED11[14], RDSR, TDSR, MRBR[2], RSFL, RSEM,
      RAEM, RAFL, TSEM, TAEM, TAFL, TIPG, FTRL, RESERVED12[3], TACC, RACC,
      RESERVED13[15], RMON_T_PACKETS, RMON_T_BC_PKT, RMON_T_MC_PKT,
      RMON_T_CRC_ALIGN, RMON_T_UNDERSIZE, RMON_T_OVERSIZE, RMON_T_FRAG,
      RMON_T_JAB, RMON_T_COL, RMON_T_P64, RMON_T_P65TO127, RMON_T_P128TO255,
      RMON_T_P256TO511, RMON_T_P512TO1023, RMON_T_P1024TO2048, RMON_T_GTE2048,
      RMON_T_OCTETS, IEEE_T_DROP, IEEE_T_FRAME_OK, IEEE_T_1COL, IEEE_T_MCOL,
      IEEE_T_DEF, IEEE_T_LCOL, IEEE_T_EXCOL, IEEE_T_MACERR, IEEE_T_CSERR,
      IEEE_T_SQE, IEEE_T_FDXFC, IEEE_T_OCTETS_OK, RESERVED14[3], RMON_R_PACKETS,
      RMON_R_BC_PKT, RMON_R_MC_PKT, RMON_R_CRC_ALIGN, RMON_R_UNDERSIZE,
      RMON_R_OVERSIZE, RMON_R_FRAG, RMON_R_JAB, RESERVED15, RMON_R_P64,
      RMON_R_P65TO127, RMON_R_P128TO255, RMON_R_P256TO511, RMON_R_P512TO1023,
      RMON_R_P1024TO2047, RMON_R_GTE2048, RMON_R_OCTETS, IEEE_R_DROP,
      IEEE_R_FRAME_OK, IEEE_R_CRC, IEEE_R_ALIGN, IEEE_R_MACERR, IEEE_R_FDXFC,
      IEEE_R_OCTETS_OK, RESERVED16[71], ATCR, ATVR, ATOFF, ATPER, ATCOR, ATINC,
      ATSTMP, RESERVED17[122], TGSR, TCSR0, TCCR0, TCSR1, TCCR1, TCSR2, TCCR2,
      TCSR3;
};

#undef ENET
#if defined(MG_DRIVER_IMXRT_RT11) && MG_DRIVER_IMXRT_RT11
#define ENET ((struct imxrt_enet *) (uintptr_t) 0x40424000U)
#define ETH_DESC_CNT 5     // Descriptors count
#else
#define ENET ((struct imxrt_enet *) (uintptr_t) 0x402D8000U)
#define ETH_DESC_CNT 4     // Descriptors count
#endif

#define ETH_PKT_SIZE 1536  // Max frame size, 64-bit aligned

struct enet_desc {
  uint16_t length;   // Data length
  uint16_t control;  // Control and status
  uint32_t *buffer;  // Data ptr
};

// TODO(): handle these in a portable compiler-independent CMSIS-friendly way
#define MG_64BYTE_ALIGNED __attribute__((aligned((64U))))

// Descriptors: in non-cached area (TODO(scaprile)), (37.5.1.22.2 37.5.1.23.2)
// Buffers: 64-byte aligned (37.3.14)
static volatile struct enet_desc s_rxdesc[ETH_DESC_CNT] MG_64BYTE_ALIGNED;
static volatile struct enet_desc s_txdesc[ETH_DESC_CNT] MG_64BYTE_ALIGNED;
static uint8_t s_rxbuf[ETH_DESC_CNT][ETH_PKT_SIZE] MG_64BYTE_ALIGNED;
static uint8_t s_txbuf[ETH_DESC_CNT][ETH_PKT_SIZE] MG_64BYTE_ALIGNED;
static struct mg_tcpip_if *s_ifp;  // MIP interface

static uint16_t enet_read_phy(uint8_t addr, uint8_t reg) {
  ENET->EIR |= MG_BIT(23);  // MII interrupt clear
  ENET->MMFR = (1 << 30) | (2 << 28) | (addr << 23) | (reg << 18) | (2 << 16);
  while ((ENET->EIR & MG_BIT(23)) == 0) (void) 0;
  return ENET->MMFR & 0xffff;
}

static void enet_write_phy(uint8_t addr, uint8_t reg, uint16_t val) {
  ENET->EIR |= MG_BIT(23);  // MII interrupt clear
  ENET->MMFR =
      (1 << 30) | (1 << 28) | (addr << 23) | (reg << 18) | (2 << 16) | val;
  while ((ENET->EIR & MG_BIT(23)) == 0) (void) 0;
}

//  MDC clock is generated from IPS Bus clock (ipg_clk); as per 802.3,
//  it must not exceed 2.5MHz
// The PHY receives the PLL6-generated 50MHz clock
static bool mg_tcpip_driver_imxrt_init(struct mg_tcpip_if *ifp) {
  struct mg_tcpip_driver_imxrt_data *d =
      (struct mg_tcpip_driver_imxrt_data *) ifp->driver_data;
  s_ifp = ifp;

  // Init RX descriptors
  for (int i = 0; i < ETH_DESC_CNT; i++) {
    s_rxdesc[i].control = MG_BIT(15);              // Own (E)
    s_rxdesc[i].buffer = (uint32_t *) s_rxbuf[i];  // Point to data buffer
  }
  s_rxdesc[ETH_DESC_CNT - 1].control |= MG_BIT(13);  // Wrap last descriptor

  // Init TX descriptors
  for (int i = 0; i < ETH_DESC_CNT; i++) {
    // s_txdesc[i].control = MG_BIT(10);  // Own (TC)
    s_txdesc[i].buffer = (uint32_t *) s_txbuf[i];
  }
  s_txdesc[ETH_DESC_CNT - 1].control |= MG_BIT(13);  // Wrap last descriptor

  ENET->ECR = MG_BIT(0);                     // Software reset, disable
  while ((ENET->ECR & MG_BIT(0))) (void) 0;  // Wait until done

  // Set MDC clock divider. If user told us the value, use it.
  // TODO(): Otherwise, guess (currently assuming max freq)
  int cr = (d == NULL || d->mdc_cr < 0) ? 24 : d->mdc_cr;
  ENET->MSCR = (1 << 8) | ((cr & 0x3f) << 1);  // HOLDTIME 2 clks
  struct mg_phy phy = {enet_read_phy, enet_write_phy};
  mg_phy_init(&phy, d->phy_addr, MG_PHY_LEDS_ACTIVE_HIGH); // MAC clocks PHY  
  // Select RMII mode, 100M, keep CRC, set max rx length, disable loop
  ENET->RCR = (1518 << 16) | MG_BIT(8) | MG_BIT(2);
  // ENET->RCR |= MG_BIT(3);     // Receive all
  ENET->TCR = MG_BIT(2);  // Full-duplex
  ENET->RDSR = (uint32_t) (uintptr_t) s_rxdesc;
  ENET->TDSR = (uint32_t) (uintptr_t) s_txdesc;
  ENET->MRBR[0] = ETH_PKT_SIZE;  // Same size for RX/TX buffers
  // MAC address filtering (bytes in reversed order)
  ENET->PAUR = ((uint32_t) ifp->mac[4] << 24U) | (uint32_t) ifp->mac[5] << 16U;
  ENET->PALR = (uint32_t) (ifp->mac[0] << 24U) |
               ((uint32_t) ifp->mac[1] << 16U) |
               ((uint32_t) ifp->mac[2] << 8U) | ifp->mac[3];
  ENET->ECR = MG_BIT(8) | MG_BIT(1);  // Little-endian CPU, Enable
  ENET->EIMR = MG_BIT(25);            // Set interrupt mask
  ENET->RDAR = MG_BIT(24);            // Receive Descriptors have changed
  ENET->TDAR = MG_BIT(24);            // Transmit Descriptors have changed
  // ENET->OPD = 0x10014;
  return true;
}

// Transmit frame
static size_t mg_tcpip_driver_imxrt_tx(const void *buf, size_t len,
                                       struct mg_tcpip_if *ifp) {
  static int s_txno;  // Current descriptor index
  if (len > sizeof(s_txbuf[ETH_DESC_CNT])) {
    MG_ERROR(("Frame too big, %ld", (long) len));
    len = (size_t) -1;  // fail
  } else if ((s_txdesc[s_txno].control & MG_BIT(15))) {
    ifp->nerr++;
    MG_ERROR(("No descriptors available"));
    len = 0;  // retry later
  } else {
    memcpy(s_txbuf[s_txno], buf, len);         // Copy data
    s_txdesc[s_txno].length = (uint16_t) len;  // Set data len
    // Table 37-34, R, L, TC (Ready, last, transmit CRC after frame
    s_txdesc[s_txno].control |=
        (uint16_t) (MG_BIT(15) | MG_BIT(11) | MG_BIT(10));
    ENET->TDAR = MG_BIT(24);  // Descriptor ring updated
    if (++s_txno >= ETH_DESC_CNT) s_txno = 0;
  }
  (void) ifp;
  return len;
}

static bool mg_tcpip_driver_imxrt_poll(struct mg_tcpip_if *ifp, bool s1) {
  if (!s1) return false;
  struct mg_tcpip_driver_imxrt_data *d =
      (struct mg_tcpip_driver_imxrt_data *) ifp->driver_data;
  uint8_t speed = MG_PHY_SPEED_10M;
  bool up = false, full_duplex = false;
  struct mg_phy phy = {enet_read_phy, enet_write_phy};
  up = mg_phy_up(&phy, d->phy_addr, &full_duplex, &speed);
  if ((ifp->state == MG_TCPIP_STATE_DOWN) && up) {  // link state just went up
    // tmp = reg with flags set to the most likely situation: 100M full-duplex
    // if(link is slow or half) set flags otherwise
    // reg = tmp
    uint32_t tcr = ENET->TCR | MG_BIT(2);             // Full-duplex
    uint32_t rcr = ENET->RCR & ~MG_BIT(9);            // 100M
    if (speed == MG_PHY_SPEED_10M) rcr |= MG_BIT(9);  // 10M
    if (full_duplex == false) tcr &= ~MG_BIT(2);      // Half-duplex
    ENET->TCR = tcr;  // IRQ handler does not fiddle with these registers
    ENET->RCR = rcr;
    MG_DEBUG(("Link is %uM %s-duplex", rcr & MG_BIT(9) ? 10 : 100,
              tcr & MG_BIT(2) ? "full" : "half"));
  }
  return up;
}

void ENET_IRQHandler(void);
static uint32_t s_rxno;
void ENET_IRQHandler(void) {
  ENET->EIR = MG_BIT(25);  // Ack IRQ
  // Frame received, loop
  for (uint32_t i = 0; i < 10; i++) {  // read as they arrive but not forever
    uint32_t r = s_rxdesc[s_rxno].control;
    if (r & MG_BIT(15)) break;  // exit when done
    // skip partial/errored frames (Table 37-32)
    if ((r & MG_BIT(11)) &&
        !(r & (MG_BIT(5) | MG_BIT(4) | MG_BIT(2) | MG_BIT(1) | MG_BIT(0)))) {
      size_t len = s_rxdesc[s_rxno].length;
      mg_tcpip_qwrite(s_rxbuf[s_rxno], len > 4 ? len - 4 : len, s_ifp);
    }
    s_rxdesc[s_rxno].control |= MG_BIT(15);
    if (++s_rxno >= ETH_DESC_CNT) s_rxno = 0;
  }
  ENET->RDAR = MG_BIT(24);  // Receive Descriptors have changed
  // If b24 == 0, descriptors were exhausted and probably frames were dropped
}

struct mg_tcpip_driver mg_tcpip_driver_imxrt = {mg_tcpip_driver_imxrt_init,
                                                mg_tcpip_driver_imxrt_tx, NULL,
                                                mg_tcpip_driver_imxrt_poll};

#endif

#ifdef MG_ENABLE_LINES
#line 1 "src/drivers/phy.c"
#endif


enum {                      // ID1  ID2
  MG_PHY_KSZ8x = 0x22,      // 0022 1561 - KSZ8081RNB
  MG_PHY_DP83x = 0x2000,
  MG_PHY_DP83867 = 0xa231,  // 2000 a231 - TI DP83867I
  MG_PHY_DP83825 = 0xa140,  // 2000 a140 - TI DP83825I
  MG_PHY_DP83848 = 0x5ca2,  // 2000 5ca2 - TI DP83848I
  MG_PHY_LAN87x = 0x7,      // 0007 c0fx - LAN8720
  MG_PHY_RTL8201 = 0x1C     // 001c c816 - RTL8201
};

enum {
  MG_PHY_REG_BCR = 0,
  MG_PHY_REG_BSR = 1,
  MG_PHY_REG_ID1 = 2,
  MG_PHY_REG_ID2 = 3,
  MG_PHY_DP83x_REG_PHYSTS = 16,
  MG_PHY_DP83867_REG_PHYSTS = 17,
  MG_PHY_DP83x_REG_RCSR = 23,
  MG_PHY_DP83x_REG_LEDCR = 24,
  MG_PHY_KSZ8x_REG_PC1R = 30,
  MG_PHY_KSZ8x_REG_PC2R = 31,
  MG_PHY_LAN87x_REG_SCSR = 31,
  MG_PHY_RTL8201_REG_RMSR = 16,  // in page 7
  MG_PHY_RTL8201_REG_PAGESEL = 31
};

static const char *mg_phy_id_to_str(uint16_t id1, uint16_t id2) {
  switch (id1) {
    case MG_PHY_DP83x:
      switch (id2) {
        case MG_PHY_DP83867:
          return "DP83867";
        case MG_PHY_DP83848:
          return "DP83848";
        case MG_PHY_DP83825:
          return "DP83825";
        default:
          return "DP83x";
      }
    case MG_PHY_KSZ8x:
      return "KSZ8x";
    case MG_PHY_LAN87x:
      return "LAN87x";
    case MG_PHY_RTL8201:
      return "RTL8201";
    default:
      return "unknown";
  }
  (void) id2;
}

void mg_phy_init(struct mg_phy *phy, uint8_t phy_addr, uint8_t config) {
  uint16_t id1, id2;
  phy->write_reg(phy_addr, MG_PHY_REG_BCR, MG_BIT(15));  // Reset PHY
  while (phy->read_reg(phy_addr, MG_PHY_REG_BCR) & MG_BIT(15)) (void) 0;
  // MG_PHY_REG_BCR[12]: Autonegotiation is default unless hw says otherwise

  id1 = phy->read_reg(phy_addr, MG_PHY_REG_ID1);
  id2 = phy->read_reg(phy_addr, MG_PHY_REG_ID2);
  MG_INFO(("PHY ID: %#04x %#04x (%s)", id1, id2, mg_phy_id_to_str(id1, id2)));

  if (id1 == MG_PHY_DP83x && id2 == MG_PHY_DP83867) {
    phy->write_reg(phy_addr, 0x0d, 0x1f);  // write 0x10d to IO_MUX_CFG (0x0170)
    phy->write_reg(phy_addr, 0x0e, 0x170);
    phy->write_reg(phy_addr, 0x0d, 0x401f);
    phy->write_reg(phy_addr, 0x0e, 0x10d);
  }

  if (config & MG_PHY_CLOCKS_MAC) {
    // Use PHY crystal oscillator (preserve defaults)
    // nothing to do
  } else {  // MAC clocks PHY, PHY has no xtal
    // Enable 50 MHz external ref clock at XI (preserve defaults)
    if (id1 == MG_PHY_DP83x && id2 != MG_PHY_DP83867 && id2 != MG_PHY_DP83848) {
      phy->write_reg(phy_addr, MG_PHY_DP83x_REG_RCSR, MG_BIT(7) | MG_BIT(0));
    } else if (id1 == MG_PHY_KSZ8x) {
      // Disable isolation (override hw, it doesn't make sense at this point)
      phy->write_reg(  // #2848, some NXP boards set ISO, even though
          phy_addr, MG_PHY_REG_BCR,  // docs say they don't
          phy->read_reg(phy_addr, MG_PHY_REG_BCR) & (uint16_t) ~MG_BIT(10));
      phy->write_reg(phy_addr, MG_PHY_KSZ8x_REG_PC2R,  // now do clock stuff
                     MG_BIT(15) | MG_BIT(8) | MG_BIT(7));
    } else if (id1 == MG_PHY_LAN87x) {
      // nothing to do
    } else if (id1 == MG_PHY_RTL8201) {
      // assume PHY has been hardware strapped properly
#if 0
      phy->write_reg(phy_addr, MG_PHY_RTL8201_REG_PAGESEL, 7);  // Select page 7
      phy->write_reg(phy_addr, MG_PHY_RTL8201_REG_RMSR, 0x1ffa);
      phy->write_reg(phy_addr, MG_PHY_RTL8201_REG_PAGESEL, 0);  // Select page 0
#endif
    }
  }

  if (config & MG_PHY_LEDS_ACTIVE_HIGH && id1 == MG_PHY_DP83x) {
    phy->write_reg(phy_addr, MG_PHY_DP83x_REG_LEDCR,
                   MG_BIT(9) | MG_BIT(7));  // LED status, active high
  }  // Other PHYs do not support this feature
}

bool mg_phy_up(struct mg_phy *phy, uint8_t phy_addr, bool *full_duplex,
               uint8_t *speed) {
  bool up = false;
  uint16_t bsr = phy->read_reg(phy_addr, MG_PHY_REG_BSR);
  if ((bsr & MG_BIT(5)) && !(bsr & MG_BIT(2)))  // some PHYs latch down events
    bsr = phy->read_reg(phy_addr, MG_PHY_REG_BSR);  // read again
  up = bsr & MG_BIT(2);
  if (up && full_duplex != NULL && speed != NULL) {
    uint16_t id1 = phy->read_reg(phy_addr, MG_PHY_REG_ID1);
    if (id1 == MG_PHY_DP83x) {
      uint16_t id2 = phy->read_reg(phy_addr, MG_PHY_REG_ID2);
      if (id2 == MG_PHY_DP83867) {
        uint16_t physts = phy->read_reg(phy_addr, MG_PHY_DP83867_REG_PHYSTS);
        *full_duplex = physts & MG_BIT(13);
        *speed = (physts & MG_BIT(15))   ? MG_PHY_SPEED_1000M
                 : (physts & MG_BIT(14)) ? MG_PHY_SPEED_100M
                                         : MG_PHY_SPEED_10M;
      } else {
        uint16_t physts = phy->read_reg(phy_addr, MG_PHY_DP83x_REG_PHYSTS);
        *full_duplex = physts & MG_BIT(2);
        *speed = (physts & MG_BIT(1)) ? MG_PHY_SPEED_10M : MG_PHY_SPEED_100M;
      }
    } else if (id1 == MG_PHY_KSZ8x) {
      uint16_t pc1r = phy->read_reg(phy_addr, MG_PHY_KSZ8x_REG_PC1R);
      *full_duplex = pc1r & MG_BIT(2);
      *speed = (pc1r & 3) == 1 ? MG_PHY_SPEED_10M : MG_PHY_SPEED_100M;
    } else if (id1 == MG_PHY_LAN87x) {
      uint16_t scsr = phy->read_reg(phy_addr, MG_PHY_LAN87x_REG_SCSR);
      *full_duplex = scsr & MG_BIT(4);
      *speed = (scsr & MG_BIT(3)) ? MG_PHY_SPEED_100M : MG_PHY_SPEED_10M;
    } else if (id1 == MG_PHY_RTL8201) {
      uint16_t bcr = phy->read_reg(phy_addr, MG_PHY_REG_BCR);
      *full_duplex = bcr & MG_BIT(8);
      *speed = (bcr & MG_BIT(13)) ? MG_PHY_SPEED_100M : MG_PHY_SPEED_10M;
    }
  }
  return up;
}

#ifdef MG_ENABLE_LINES
#line 1 "src/drivers/pico-w.c"
#endif
#if MG_ENABLE_TCPIP && MG_ARCH == MG_ARCH_PICOSDK && \
    defined(MG_ENABLE_DRIVER_PICO_W) && MG_ENABLE_DRIVER_PICO_W





static struct mg_tcpip_if *s_ifp;

static bool mg_tcpip_driver_pico_w_init(struct mg_tcpip_if *ifp) {
  struct mg_tcpip_driver_pico_w_data *d =
      (struct mg_tcpip_driver_pico_w_data *) ifp->driver_data;
  s_ifp = ifp;
  if (cyw43_arch_init() != 0)
    return false;  // initialize async_context and WiFi chip
  if (d->apmode && d->apssid != NULL) {
    MG_DEBUG(("Starting AP '%s' (%u)", d->apssid, d->apchannel));
    if (!mg_wifi_ap_start(d->apssid, d->appass, d->apchannel)) return false;
    cyw43_wifi_get_mac(&cyw43_state, CYW43_ITF_STA, ifp->mac);  // same MAC
  } else {
    cyw43_arch_enable_sta_mode();
    cyw43_wifi_get_mac(&cyw43_state, CYW43_ITF_STA, ifp->mac);
    if (d->ssid != NULL) {
      MG_DEBUG(("Connecting to '%s'", d->ssid));
      return mg_wifi_connect(d->ssid, d->pass);
    } else {
      cyw43_arch_disable_sta_mode();
    }
  }
  return true;
}

static size_t mg_tcpip_driver_pico_w_tx(const void *buf, size_t len,
                                        struct mg_tcpip_if *ifp) {
  struct mg_tcpip_driver_pico_w_data *d =
      (struct mg_tcpip_driver_pico_w_data *) ifp->driver_data;
  return cyw43_send_ethernet(&cyw43_state,
                             d->apmode ? CYW43_ITF_AP : CYW43_ITF_STA, len, buf,
                             false) == 0
             ? len
             : 0;
}

static bool s_aplink = false, s_scanning = false;
static bool s_stalink = false, s_connecting = false;

static bool mg_tcpip_driver_pico_w_poll(struct mg_tcpip_if *ifp, bool s1) {
  cyw43_arch_poll();  // not necessary, except when IRQs are disabled (OTA)
  if (s_scanning && !cyw43_wifi_scan_active(&cyw43_state)) {
    MG_VERBOSE(("scan complete"));
    s_scanning = 0;
    mg_tcpip_call(s_ifp, MG_TCPIP_EV_WIFI_SCAN_END, NULL);
  }
  if (!s1) return false;
  struct mg_tcpip_driver_pico_w_data *d =
      (struct mg_tcpip_driver_pico_w_data *) ifp->driver_data;
  if (d->apmode) return s_aplink;
  int sdkstate = cyw43_wifi_link_status(&cyw43_state, CYW43_ITF_STA);
  MG_VERBOSE(("conn: %c state: %d", s_connecting ? '1' : '0', sdkstate));
  if (sdkstate < 0 && s_connecting) {
    mg_tcpip_call(s_ifp, MG_TCPIP_EV_WIFI_CONNECT_ERR, &sdkstate);
    s_connecting = false;
  }
  return s_stalink;
}

struct mg_tcpip_driver mg_tcpip_driver_pico_w = {
    mg_tcpip_driver_pico_w_init,
    mg_tcpip_driver_pico_w_tx,
    NULL,
    mg_tcpip_driver_pico_w_poll,
};

// Called once per outstanding frame by async_context
void cyw43_cb_process_ethernet(void *cb_data, int itf, size_t len,
                               const uint8_t *buf) {
  mg_tcpip_qwrite((void *) buf, len, s_ifp);
  (void) cb_data;
}

// Called by async_context
void cyw43_cb_tcpip_set_link_up(cyw43_t *self, int itf) {
  if (itf == CYW43_ITF_AP) {
    s_aplink = true;
  } else {
    s_stalink = true;
    s_connecting = false;
  }
}
void cyw43_cb_tcpip_set_link_down(cyw43_t *self, int itf) {
  if (itf == CYW43_ITF_AP) {
     s_aplink = false;
  } else {
    s_stalink = false;
    // SDK calls this before we check status, don't clear s_connecting here
  }
}

// there's life beyond lwIP
void pbuf_copy_partial(void) {
  (void) 0;
}

static int result_cb(void *arg, const cyw43_ev_scan_result_t *data) {
  struct mg_wifi_scan_bss_data bss;
  bss.SSID = mg_str_n(data->ssid, data->ssid_len);
  bss.BSSID = (char *) data->bssid;
  bss.RSSI = (int8_t) data->rssi;
  bss.has_n = 0;  // SDK ignores this
  bss.channel = (uint8_t) data->channel;
  bss.band = MG_WIFI_BAND_2G;
  // SDK-internal dependency, 2.1.0
  bss.security = data->auth_mode & MG_BIT(0) ? MG_WIFI_SECURITY_WEP
                                             : MG_WIFI_SECURITY_OPEN;
  if (data->auth_mode & MG_BIT(1)) bss.security |= MG_WIFI_SECURITY_WPA;
  if (data->auth_mode & MG_BIT(2)) bss.security |= MG_WIFI_SECURITY_WPA2;
  MG_VERBOSE(("BSS: %.*s (%u) (%M) %d dBm %u", bss.SSID.len, bss.SSID.buf,
              bss.channel, mg_print_mac, bss.BSSID, (int) bss.RSSI,
              bss.security));
  mg_tcpip_call(s_ifp, MG_TCPIP_EV_WIFI_SCAN_RESULT, &bss);
  return 0;
}

bool mg_wifi_scan(void) {
  cyw43_wifi_scan_options_t opts;
  memset(&opts, 0, sizeof(opts));
  bool res = (cyw43_wifi_scan(&cyw43_state, &opts, NULL, result_cb) == 0);
  if (res) s_scanning = true;
  return res;
}

bool mg_wifi_connect(char *ssid, char *pass) {
  cyw43_arch_enable_sta_mode();
  int res = cyw43_arch_wifi_connect_async(ssid, pass, CYW43_AUTH_WPA2_AES_PSK);
  MG_VERBOSE(("res: %d", res));
  if (res == 0) s_connecting = true;
  return (res == 0);
}

bool mg_wifi_disconnect(void) {
  cyw43_arch_disable_sta_mode();
  s_connecting = false;
  return true;
}

bool mg_wifi_ap_start(char *ssid, char *pass, unsigned int channel) {
  cyw43_wifi_ap_set_channel(&cyw43_state, channel);
  cyw43_arch_enable_ap_mode(ssid, pass, CYW43_AUTH_WPA2_AES_PSK);
  return true;
}

bool mg_wifi_ap_stop(void) {
  cyw43_arch_disable_ap_mode();
  return true;
}

#endif

#ifdef MG_ENABLE_LINES
#line 1 "src/drivers/ppp.c"
#endif


#if MG_ENABLE_TCPIP && defined(MG_ENABLE_DRIVER_PPP) && MG_ENABLE_DRIVER_PPP

#define MG_PPP_FLAG 0x7e  // PPP frame delimiter
#define MG_PPP_ESC 0x7d   // PPP escape byte for special characters
#define MG_PPP_ADDR 0xff
#define MG_PPP_CTRL 0x03

#define MG_PPP_PROTO_IP 0x0021
#define MG_PPP_PROTO_LCP 0xc021
#define MG_PPP_PROTO_IPCP 0x8021

#define MG_PPP_IPCP_REQ 1
#define MG_PPP_IPCP_ACK 2
#define MG_PPP_IPCP_NACK 3
#define MG_PPP_IPCP_IPADDR 3

#define MG_PPP_LCP_CFG_REQ 1
#define MG_PPP_LCP_CFG_ACK 2
#define MG_PPP_LCP_CFG_NACK 3
#define MG_PPP_LCP_CFG_REJECT 4
#define MG_PPP_LCP_CFG_TERM_REQ 5
#define MG_PPP_LCP_CFG_TERM_ACK 6

#define MG_PPP_AT_TIMEOUT 2000

static size_t print_atcmd(void (*out)(char, void *), void *arg, va_list *ap) {
  struct mg_str s = va_arg(*ap, struct mg_str);
  for (size_t i = 0; i < s.len; i++) out(s.buf[i] < 0x20 ? '.' : s.buf[i], arg);
  return s.len;
}

static void mg_ppp_reset(struct mg_tcpip_driver_ppp_data *dd) {
  dd->script_index = 0;
  dd->deadline = 0;
  if (dd->reset) dd->reset(dd->uart);
}

static bool mg_ppp_atcmd_handle(struct mg_tcpip_if *ifp) {
  struct mg_tcpip_driver_ppp_data *dd =
      (struct mg_tcpip_driver_ppp_data *) ifp->driver_data;
  if (dd->script == NULL || dd->script_index < 0) return true;
  if (dd->deadline == 0) dd->deadline = mg_millis() + MG_PPP_AT_TIMEOUT;
  for (;;) {
    if (dd->script_index % 2 == 0) {  // send AT command
      const char *cmd = dd->script[dd->script_index];
      MG_DEBUG(("send AT[%d]: %M", dd->script_index, print_atcmd, mg_str(cmd)));
      while (*cmd) dd->tx(dd->uart, *cmd++);
      dd->script_index++;
      ifp->recv_queue.head = 0;
    } else {  // check AT command response
      const char *expect = dd->script[dd->script_index];
      struct mg_queue *q = &ifp->recv_queue;
      for (;;) {
        int c;
        int is_timeout = dd->deadline > 0 && mg_millis() > dd->deadline;
        int is_overflow = q->head >= q->size - 1;
        if (is_timeout || is_overflow) {
          MG_ERROR(("AT error: %s, retrying...",
                    is_timeout ? "timeout" : "overflow"));
          mg_ppp_reset(dd);
          return false;  // FAIL: timeout
        }
        if ((c = dd->rx(dd->uart)) < 0) return false;  // no data
        q->buf[q->head++] = c;
        if (mg_match(mg_str_n(q->buf, q->head), mg_str(expect), NULL)) {
          MG_DEBUG(("recv AT[%d]: %M", dd->script_index, print_atcmd,
                    mg_str_n(q->buf, q->head)));
          dd->script_index++;
          q->head = 0;
          break;
        }
      }
    }
    if (dd->script[dd->script_index] == NULL) {
      MG_DEBUG(("finished AT script"));
      dd->script_index = -1;
      return true;
    }
  }
}

static bool mg_ppp_init(struct mg_tcpip_if *ifp) {
  ifp->recv_queue.size = 3000;  // MTU=1500, worst case escaping = 2x
  return true;
}

// Calculate FCS/CRC for PPP frames. Could be implemented faster using lookup
// tables.
static uint32_t fcs_do(uint32_t fcs, uint8_t x) {
  for (int i = 0; i < 8; i++) {
    fcs = ((fcs ^ x) & 1) ? (fcs >> 1) ^ 0x8408 : fcs >> 1;
    x >>= 1;
  }
  return fcs;
}

static bool mg_ppp_poll(struct mg_tcpip_if *ifp, bool s1) {
  (void) s1;
  return ifp->driver_data != NULL;
}

// Transmit a single byte as part of the PPP frame (escaped, if needed)
static void mg_ppp_tx_byte(struct mg_tcpip_driver_ppp_data *dd, uint8_t b) {
  if ((b < 0x20) || (b == MG_PPP_ESC) || (b == MG_PPP_FLAG)) {
    dd->tx(dd->uart, MG_PPP_ESC);
    dd->tx(dd->uart, b ^ 0x20);
  } else {
    dd->tx(dd->uart, b);
  }
}

// Transmit a single PPP frame for the given protocol
static void mg_ppp_tx_frame(struct mg_tcpip_driver_ppp_data *dd, uint16_t proto,
                            uint8_t *data, size_t datasz) {
  uint16_t crc;
  uint32_t fcs = 0xffff;

  dd->tx(dd->uart, MG_PPP_FLAG);
  mg_ppp_tx_byte(dd, MG_PPP_ADDR);
  mg_ppp_tx_byte(dd, MG_PPP_CTRL);
  mg_ppp_tx_byte(dd, proto >> 8);
  mg_ppp_tx_byte(dd, proto & 0xff);
  fcs = fcs_do(fcs, MG_PPP_ADDR);
  fcs = fcs_do(fcs, MG_PPP_CTRL);
  fcs = fcs_do(fcs, proto >> 8);
  fcs = fcs_do(fcs, proto & 0xff);
  for (unsigned int i = 0; i < datasz; i++) {
    mg_ppp_tx_byte(dd, data[i]);
    fcs = fcs_do(fcs, data[i]);
  }
  crc = fcs & 0xffff;
  mg_ppp_tx_byte(dd, ~crc);  // send CRC, note the byte order
  mg_ppp_tx_byte(dd, ~crc >> 8);
  dd->tx(dd->uart, MG_PPP_FLAG);  // end of frame
}

// Send Ethernet frame as PPP frame
static size_t mg_ppp_tx(const void *buf, size_t len, struct mg_tcpip_if *ifp) {
  struct mg_tcpip_driver_ppp_data *dd =
      (struct mg_tcpip_driver_ppp_data *) ifp->driver_data;
  if (ifp->state != MG_TCPIP_STATE_READY) return 0;
  // XXX: what if not an IP protocol?
  mg_ppp_tx_frame(dd, MG_PPP_PROTO_IP, (uint8_t *) buf + 14, len - 14);
  return len;
}

// Given a full PPP frame, unescape it in place and verify FCS, returns actual
// data size on success or 0 on error.
static size_t mg_ppp_verify_frame(uint8_t *buf, size_t bufsz) {
  int unpack = 0;
  uint16_t crc;
  size_t pktsz = 0;
  uint32_t fcs = 0xffff;
  for (unsigned int i = 0; i < bufsz; i++) {
    if (unpack == 0) {
      if (buf[i] == 0x7d) {
        unpack = 1;
      } else {
        buf[pktsz] = buf[i];
        fcs = fcs_do(fcs, buf[pktsz]);
        pktsz++;
      }
    } else {
      unpack = 0;
      buf[pktsz] = buf[i] ^ 0x20;
      fcs = fcs_do(fcs, buf[pktsz]);
      pktsz++;
    }
  }
  crc = fcs & 0xffff;
  if (crc != 0xf0b8) {
    MG_DEBUG(("bad crc: %04x", crc));
    return 0;
  }
  if (pktsz < 6 || buf[0] != MG_PPP_ADDR || buf[1] != MG_PPP_CTRL) {
    return 0;
  }
  return pktsz - 2;  // strip FCS
}

// fetch as much data as we can, until a single PPP frame is received
static size_t mg_ppp_rx_frame(struct mg_tcpip_driver_ppp_data *dd,
                              struct mg_queue *q) {
  while (q->head < q->size) {
    int c;
    if ((c = dd->rx(dd->uart)) < 0) {
      return 0;
    }
    if (c == MG_PPP_FLAG) {
      if (q->head > 0) {
        break;
      } else {
        continue;
      }
    }
    q->buf[q->head++] = c;
  }

  size_t n = mg_ppp_verify_frame((uint8_t *) q->buf, q->head);
  if (n == 0) {
    MG_DEBUG(("invalid PPP frame of %d bytes", q->head));
    q->head = 0;
    return 0;
  }
  q->head = n;
  return q->head;
}

static void mg_ppp_handle_lcp(struct mg_tcpip_if *ifp, uint8_t *lcp,
                              size_t lcpsz) {
  uint8_t id;
  uint16_t len;
  struct mg_tcpip_driver_ppp_data *dd =
      (struct mg_tcpip_driver_ppp_data *) ifp->driver_data;
  if (lcpsz < 4) return;
  id = lcp[1];
  len = (((uint16_t) lcp[2]) << 8) | (lcp[3]);
  switch (lcp[0]) {
    case MG_PPP_LCP_CFG_REQ: {
      if (len == 4) {
        MG_DEBUG(("LCP config request of %d bytes, acknowledging...", len));
        lcp[0] = MG_PPP_LCP_CFG_ACK;
        mg_ppp_tx_frame(dd, MG_PPP_PROTO_LCP, lcp, len);
        lcp[0] = MG_PPP_LCP_CFG_REQ;
        mg_ppp_tx_frame(dd, MG_PPP_PROTO_LCP, lcp, len);
      } else {
        MG_DEBUG(("LCP config request of %d bytes, rejecting...", len));
        lcp[0] = MG_PPP_LCP_CFG_REJECT;
        mg_ppp_tx_frame(dd, MG_PPP_PROTO_LCP, lcp, len);
      }
    } break;
    case MG_PPP_LCP_CFG_TERM_REQ: {
      uint8_t ack[4] = {MG_PPP_LCP_CFG_TERM_ACK, id, 0, 4};
      MG_DEBUG(("LCP termination request, acknowledging..."));
      mg_ppp_tx_frame(dd, MG_PPP_PROTO_LCP, ack, sizeof(ack));
      mg_ppp_reset(dd);
      ifp->state = MG_TCPIP_STATE_UP;
      if (dd->reset) dd->reset(dd->uart);
    } break;
  }
}

static void mg_ppp_handle_ipcp(struct mg_tcpip_if *ifp, uint8_t *ipcp,
                               size_t ipcpsz) {
  struct mg_tcpip_driver_ppp_data *dd =
      (struct mg_tcpip_driver_ppp_data *) ifp->driver_data;
  uint16_t len;
  uint8_t id;
  uint8_t req[] = {
      MG_PPP_IPCP_REQ, 0, 0, 10, MG_PPP_IPCP_IPADDR, 6, 0, 0, 0, 0};
  if (ipcpsz < 4) return;
  id = ipcp[1];
  len = (((uint16_t) ipcp[2]) << 8) | (ipcp[3]);
  switch (ipcp[0]) {
    case MG_PPP_IPCP_REQ:
      MG_DEBUG(("got IPCP config request, acknowledging..."));
      if (len >= 10 && ipcp[4] == MG_PPP_IPCP_IPADDR) {
        uint8_t *ip = ipcp + 6;
        MG_DEBUG(("host ip: %d.%d.%d.%d", ip[0], ip[1], ip[2], ip[3]));
      }
      ipcp[0] = MG_PPP_IPCP_ACK;
      mg_ppp_tx_frame(dd, MG_PPP_PROTO_IPCP, ipcp, len);
      req[1] = id;
      // Request IP address 0.0.0.0
      mg_ppp_tx_frame(dd, MG_PPP_PROTO_IPCP, req, sizeof(req));
      break;
    case MG_PPP_IPCP_ACK:
      // This usually does not happen, as our "preferred" IP address is invalid
      MG_DEBUG(("got IPCP config ack, link is online now"));
      ifp->state = MG_TCPIP_STATE_READY;
      break;
    case MG_PPP_IPCP_NACK:
      MG_DEBUG(("got IPCP config nack"));
      // NACK contains our "suggested" IP address, use it
      if (len >= 10 && ipcp[4] == MG_PPP_IPCP_IPADDR) {
        uint8_t *ip = ipcp + 6;
        MG_DEBUG(("ipcp ack, ip: %d.%d.%d.%d", ip[0], ip[1], ip[2], ip[3]));
        ipcp[0] = MG_PPP_IPCP_REQ;
        mg_ppp_tx_frame(dd, MG_PPP_PROTO_IPCP, ipcp, len);
        ifp->ip = ifp->mask = MG_IPV4(ip[0], ip[1], ip[2], ip[3]);
        ifp->state = MG_TCPIP_STATE_READY;
      }
      break;
  }
}

static size_t mg_ppp_rx(void *ethbuf, size_t ethlen, struct mg_tcpip_if *ifp) {
  uint8_t *eth = ethbuf;
  size_t ethsz = 0;
  struct mg_tcpip_driver_ppp_data *dd =
      (struct mg_tcpip_driver_ppp_data *) ifp->driver_data;
  uint8_t *buf = (uint8_t *) ifp->recv_queue.buf;

  if (!mg_ppp_atcmd_handle(ifp)) return 0;

  size_t bufsz = mg_ppp_rx_frame(dd, &ifp->recv_queue);
  if (!bufsz) return 0;
  uint16_t proto = (((uint16_t) buf[2]) << 8) | (uint16_t) buf[3];
  switch (proto) {
    case MG_PPP_PROTO_LCP: mg_ppp_handle_lcp(ifp, buf + 4, bufsz - 4); break;
    case MG_PPP_PROTO_IPCP: mg_ppp_handle_ipcp(ifp, buf + 4, bufsz - 4); break;
    case MG_PPP_PROTO_IP:
      MG_VERBOSE(("got IP packet of %d bytes", bufsz - 4));
      memmove(eth + 14, buf + 4, bufsz - 4);
      memmove(eth, ifp->mac, 6);
      memmove(eth + 6, "\xff\xff\xff\xff\xff\xff", 6);
      eth[12] = 0x08;
      eth[13] = 0x00;
      ethsz = bufsz - 4 + 14;
      ifp->recv_queue.head = 0;
      return ethsz;
#if 0
    default:
      MG_DEBUG(("unknown PPP frame:"));
      mg_hexdump(ppp->buf, ppp->bufsz);
#endif
  }
  ifp->recv_queue.head = 0;
  return 0;
  (void) ethlen;
}

struct mg_tcpip_driver mg_tcpip_driver_ppp = {mg_ppp_init, mg_ppp_tx, mg_ppp_rx,
                                              mg_ppp_up};

#endif

#ifdef MG_ENABLE_LINES
#line 1 "src/drivers/ra.c"
#endif


#if MG_ENABLE_TCPIP && defined(MG_ENABLE_DRIVER_RA) && MG_ENABLE_DRIVER_RA
struct ra_etherc {
  volatile uint32_t ECMR, RESERVED, RFLR, RESERVED1, ECSR, RESERVED2, ECSIPR,
      RESERVED3, PIR, RESERVED4, PSR, RESERVED5[5], RDMLR, RESERVED6[3], IPGR,
      APR, MPR, RESERVED7, RFCF, TPAUSER, TPAUSECR, BCFRR, RESERVED8[20], MAHR,
      RESERVED9, MALR, RESERVED10, TROCR, CDCR, LCCR, CNDCR, RESERVED11, CEFCR,
      FRECR, TSFRCR, TLFRCR, RFCR, MAFCR;
};

struct ra_edmac {
  volatile uint32_t EDMR, RESERVED, EDTRR, RESERVED1, EDRRR, RESERVED2, TDLAR,
      RESERVED3, RDLAR, RESERVED4, EESR, RESERVED5, EESIPR, RESERVED6, TRSCER,
      RESERVED7, RMFCR, RESERVED8, TFTR, RESERVED9, FDR, RESERVED10, RMCR,
      RESERVED11[2], TFUCR, RFOCR, IOSR, FCFTR, RESERVED12, RPADIR, TRIMD,
      RESERVED13[18], RBWAR, RDFAR, RESERVED14, TBRAR, TDFAR;
};

#undef ETHERC
#define ETHERC ((struct ra_etherc *) (uintptr_t) 0x40114100U)
#undef EDMAC
#define EDMAC ((struct ra_edmac *) (uintptr_t) 0x40114000U)
#undef RASYSC
#define RASYSC ((uint32_t *) (uintptr_t) 0x4001E000U)
#undef ICU_IELSR
#define ICU_IELSR ((uint32_t *) (uintptr_t) 0x40006300U)

#define ETH_PKT_SIZE 1536  // Max frame size, multiple of 32
#define ETH_DESC_CNT 4     // Descriptors count

// TODO(): handle these in a portable compiler-independent CMSIS-friendly way
#define MG_16BYTE_ALIGNED __attribute__((aligned((16U))))
#define MG_32BYTE_ALIGNED __attribute__((aligned((32U))))

// Descriptors: 16-byte aligned
// Buffers: 32-byte aligned (27.3.1)
static volatile uint32_t s_rxdesc[ETH_DESC_CNT][4] MG_16BYTE_ALIGNED;
static volatile uint32_t s_txdesc[ETH_DESC_CNT][4] MG_16BYTE_ALIGNED;
static uint8_t s_rxbuf[ETH_DESC_CNT][ETH_PKT_SIZE] MG_32BYTE_ALIGNED;
static uint8_t s_txbuf[ETH_DESC_CNT][ETH_PKT_SIZE] MG_32BYTE_ALIGNED;
static struct mg_tcpip_if *s_ifp;  // MIP interface

// fastest is 3 cycles (SUB + BNE) on a 3-stage pipeline or equivalent
static inline void raspin(volatile uint32_t count) {
  while (count--) (void) 0;
}
// count to get the 200ns SMC semi-cycle period (2.5MHz) calling raspin():
// SYS_FREQUENCY * 200ns / 3 = SYS_FREQUENCY / 15000000
static uint32_t s_smispin;

// Bit-banged SMI
static void smi_preamble(void) {
  unsigned int i = 32;
  uint32_t pir = MG_BIT(1) | MG_BIT(2);  // write, mdio = 1, mdc = 0
  ETHERC->PIR = pir;
  while (i--) {
    pir &= ~MG_BIT(0);  // mdc = 0
    ETHERC->PIR = pir;
    raspin(s_smispin);
    pir |= MG_BIT(0);  // mdc = 1
    ETHERC->PIR = pir;
    raspin(s_smispin);
  }
}
static void smi_wr(uint16_t header, uint16_t data) {
  uint32_t word = (header << 16) | data;
  smi_preamble();
  unsigned int i = 32;
  while (i--) {
    uint32_t pir = MG_BIT(1) |
                   (word & 0x80000000 ? MG_BIT(2) : 0);  // write, mdc = 0, data
    ETHERC->PIR = pir;
    raspin(s_smispin);
    pir |= MG_BIT(0);  // mdc = 1
    ETHERC->PIR = pir;
    raspin(s_smispin);
    word <<= 1;
  }
}
static uint16_t smi_rd(uint16_t header) {
  smi_preamble();
  unsigned int i = 16;  // 2 LSb as turnaround
  uint32_t pir;
  while (i--) {
    pir = (i > 1 ? MG_BIT(1) : 0) |
          (header & 0x8000
               ? MG_BIT(2)
               : 0);  // mdc = 0, header, set read direction at turnaround
    ETHERC->PIR = pir;
    raspin(s_smispin);
    pir |= MG_BIT(0);  // mdc = 1
    ETHERC->PIR = pir;
    raspin(s_smispin);
    header <<= 1;
  }
  i = 16;
  uint16_t data = 0;
  while (i--) {
    data <<= 1;
    pir = 0;  // read, mdc = 0
    ETHERC->PIR = pir;
    raspin(s_smispin / 2);  // 1/4 clock period, 300ns max access time
    data |= (uint16_t)(ETHERC->PIR & MG_BIT(3) ? 1 : 0);  // read mdio
    raspin(s_smispin / 2);                    // 1/4 clock period
    pir |= MG_BIT(0);                         // mdc = 1
    ETHERC->PIR = pir;
    raspin(s_smispin);
  }
  return data;
}

static uint16_t raeth_read_phy(uint8_t addr, uint8_t reg) {
  return smi_rd((uint16_t)((1 << 14) | (2 << 12) | (addr << 7) | (reg << 2) | (2 << 0)));
}

static void raeth_write_phy(uint8_t addr, uint8_t reg, uint16_t val) {
  smi_wr((uint16_t)((1 << 14) | (1 << 12) | (addr << 7) | (reg << 2) | (2 << 0)), val);
}

// MDC clock is generated manually; as per 802.3, it must not exceed 2.5MHz
static bool mg_tcpip_driver_ra_init(struct mg_tcpip_if *ifp) {
  struct mg_tcpip_driver_ra_data *d =
      (struct mg_tcpip_driver_ra_data *) ifp->driver_data;
  s_ifp = ifp;

  // Init SMI clock timing. If user told us the clock value, use it.
  // TODO(): Otherwise, guess
  s_smispin = d->clock / 15000000;

  // Init RX descriptors
  for (int i = 0; i < ETH_DESC_CNT; i++) {
    s_rxdesc[i][0] = MG_BIT(31);             // RACT
    s_rxdesc[i][1] = ETH_PKT_SIZE << 16;     // RBL
    s_rxdesc[i][2] = (uint32_t) s_rxbuf[i];  // Point to data buffer
  }
  s_rxdesc[ETH_DESC_CNT - 1][0] |= MG_BIT(30);  // Wrap last descriptor

  // Init TX descriptors
  for (int i = 0; i < ETH_DESC_CNT; i++) {
    // TACT = 0
    s_txdesc[i][2] = (uint32_t) s_txbuf[i];
  }
  s_txdesc[ETH_DESC_CNT - 1][0] |= MG_BIT(30);  // Wrap last descriptor

  EDMAC->EDMR = MG_BIT(0);  // Software reset, wait 64 PCLKA clocks (27.2.1)
  uint32_t sckdivcr = RASYSC[8];  // get divisors from SCKDIVCR (8.2.2)
  uint32_t ick = 1 << ((sckdivcr >> 24) & 7);   // sys_clock div
  uint32_t pcka = 1 << ((sckdivcr >> 12) & 7);  // pclka div
  raspin((64U * pcka) / (3U * ick));
  EDMAC->EDMR = MG_BIT(6);  // Initialize, little-endian (27.2.1)

  MG_DEBUG(("PHY addr: %d, smispin: %d", d->phy_addr, s_smispin));
  struct mg_phy phy = {raeth_read_phy, raeth_write_phy};
  mg_phy_init(&phy, d->phy_addr, 0); // MAC clocks PHY

  // Select RMII mode,
  ETHERC->ECMR = MG_BIT(2) | MG_BIT(1);  // 100M, Full-duplex, CRC
  // ETHERC->ECMR |= MG_BIT(0);             // Receive all
  ETHERC->RFLR = 1518;  // Set max rx length

  EDMAC->RDLAR = (uint32_t) (uintptr_t) s_rxdesc;
  EDMAC->TDLAR = (uint32_t) (uintptr_t) s_txdesc;
  // MAC address filtering (bytes in reversed order)
  ETHERC->MAHR = (uint32_t) (ifp->mac[0] << 24U) |
                 ((uint32_t) ifp->mac[1] << 16U) |
                 ((uint32_t) ifp->mac[2] << 8U) | ifp->mac[3];
  ETHERC->MALR = ((uint32_t) ifp->mac[4] << 8U) | ifp->mac[5];

  EDMAC->TFTR = 0;                        // Store and forward (27.2.10)
  EDMAC->FDR = 0x070f;                    // (27.2.11)
  EDMAC->RMCR = MG_BIT(0);                // (27.2.12)
  ETHERC->ECMR |= MG_BIT(6) | MG_BIT(5);  // TE RE
  EDMAC->EESIPR = MG_BIT(18);             // Enable Rx IRQ
  EDMAC->EDRRR = MG_BIT(0);               // Receive Descriptors have changed
  EDMAC->EDTRR = MG_BIT(0);               // Transmit Descriptors have changed
  return true;
}

// Transmit frame
static size_t mg_tcpip_driver_ra_tx(const void *buf, size_t len,
                                    struct mg_tcpip_if *ifp) {
  static int s_txno;  // Current descriptor index
  if (len > sizeof(s_txbuf[ETH_DESC_CNT])) {
    MG_ERROR(("Frame too big, %ld", (long) len));
    len = (size_t) -1;  // fail
  } else if ((s_txdesc[s_txno][0] & MG_BIT(31))) {
    ifp->nerr++;
    MG_ERROR(("No descriptors available"));
    len = 0;  // retry later
  } else {
    memcpy(s_txbuf[s_txno], buf, len);            // Copy data
    s_txdesc[s_txno][1] = len << 16;              // Set data len
    s_txdesc[s_txno][0] |= MG_BIT(31) | 3 << 28;  // (27.3.1.1) mark valid
    EDMAC->EDTRR = MG_BIT(0);                     // Transmit request
    if (++s_txno >= ETH_DESC_CNT) s_txno = 0;
  }
  return len;
}

static bool mg_tcpip_driver_ra_poll(struct mg_tcpip_if *ifp, bool s1) {
  if (!s1) return false;
  struct mg_tcpip_driver_ra_data *d =
      (struct mg_tcpip_driver_ra_data *) ifp->driver_data;
  uint8_t speed = MG_PHY_SPEED_10M;
  bool up = false, full_duplex = false;
  struct mg_phy phy = {raeth_read_phy, raeth_write_phy};
  up = mg_phy_up(&phy, d->phy_addr, &full_duplex, &speed);
  if ((ifp->state == MG_TCPIP_STATE_DOWN) && up) {  // link state just went up
    // tmp = reg with flags set to the most likely situation: 100M full-duplex
    // if(link is slow or half) set flags otherwise
    // reg = tmp
    uint32_t ecmr = ETHERC->ECMR | MG_BIT(2) | MG_BIT(1);  // 100M Full-duplex
    if (speed == MG_PHY_SPEED_10M) ecmr &= ~MG_BIT(2);     // 10M
    if (full_duplex == false) ecmr &= ~MG_BIT(1);          // Half-duplex
    ETHERC->ECMR = ecmr;  // IRQ handler does not fiddle with these registers
    MG_DEBUG(("Link is %uM %s-duplex", ecmr & MG_BIT(2) ? 100 : 10,
              ecmr & MG_BIT(1) ? "full" : "half"));
  }
  return up;
}

void EDMAC_IRQHandler(void);
static uint32_t s_rxno;
void EDMAC_IRQHandler(void) {
  struct mg_tcpip_driver_ra_data *d =
      (struct mg_tcpip_driver_ra_data *) s_ifp->driver_data;
  EDMAC->EESR = MG_BIT(18);            // Ack IRQ in EDMAC 1st
  ICU_IELSR[d->irqno] &= ~MG_BIT(16);  // Ack IRQ in ICU last
  // Frame received, loop
  for (uint32_t i = 0; i < 10; i++) {  // read as they arrive but not forever
    uint32_t r = s_rxdesc[s_rxno][0];
    if (r & MG_BIT(31)) break;  // exit when done
    // skip partial/errored frames (27.3.1.2)
    if ((r & (MG_BIT(29) | MG_BIT(28)) && !(r & MG_BIT(27)))) {
      size_t len = s_rxdesc[s_rxno][1] & 0xffff;
      mg_tcpip_qwrite(s_rxbuf[s_rxno], len, s_ifp);  // CRC already stripped
    }
    s_rxdesc[s_rxno][0] |= MG_BIT(31);
    if (++s_rxno >= ETH_DESC_CNT) s_rxno = 0;
  }
  EDMAC->EDRRR = MG_BIT(0);  // Receive Descriptors have changed
  // If b0 == 0, descriptors were exhausted and probably frames were dropped,
  // (27.2.9 RMFCR counts them)
}

struct mg_tcpip_driver mg_tcpip_driver_ra = {mg_tcpip_driver_ra_init,
                                             mg_tcpip_driver_ra_tx, NULL,
                                             mg_tcpip_driver_ra_poll};

#endif

#ifdef MG_ENABLE_LINES
#line 1 "src/drivers/rw612.c"
#endif


#if MG_ENABLE_TCPIP && defined(MG_ENABLE_DRIVER_RW612) && MG_ENABLE_DRIVER_RW612

struct ENET_Type {
  volatile uint32_t RESERVED_0[1], EIR, EIMR, RESERVED_1[1], RDAR, TDAR,
      RESERVED_2[3], ECR, RESERVED_3[6], MMFR, MSCR, RESERVED_4[7], MIBC,
      RESERVED_5[7], RCR, RESERVED_6[15], TCR, RESERVED_7[7], PALR, PAUR, OPD,
      TXIC[1], RESERVED_8[3], RXIC[1], RESERVED_9[5], IAUR, IALR, GAUR, GALR,
      RESERVED_10[7], TFWR, RESERVED_11[14], RDSR, TDSR, MRBR, RESERVED_12[1],
      RSFL, RSEM, RAEM, RAFL, TSEM, TAEM, TAFL, TIPG, FTRL, RESERVED_13[3],
      TACC, RACC, RESERVED_14[15], RMON_T_PACKETS, RMON_T_BC_PKT, RMON_T_MC_PKT,
      RMON_T_CRC_ALIGN, RMON_T_UNDERSIZE, RMON_T_OVERSIZE, RMON_T_FRAG,
      RMON_T_JAB, RMON_T_COL, RMON_T_P64, RMON_T_P65TO127, RMON_T_P128TO255,
      RMON_T_P256TO511, RMON_T_P512TO1023, RMON_T_P1024TO2047, RMON_T_P_GTE2048,
      RMON_T_OCTETS, IEEE_T_DROP, IEEE_T_FRAME_OK, IEEE_T_1COL, IEEE_T_MCOL,
      IEEE_T_DEF, IEEE_T_LCOL, IEEE_T_EXCOL, IEEE_T_MACERR, IEEE_T_CSERR,
      IEEE_T_SQE, IEEE_T_FDXFC, IEEE_T_OCTETS_OK, RESERVED_15[3],
      RMON_R_PACKETS, RMON_R_BC_PKT, RMON_R_MC_PKT, RMON_R_CRC_ALIGN,
      RMON_R_UNDERSIZE, RMON_R_OVERSIZE, RMON_R_FRAG, RMON_R_JAB,
      RESERVED_16[1], RMON_R_P64, RMON_R_P65TO127, RMON_R_P128TO255,
      RMON_R_P256TO511, RMON_R_P512TO1023, RMON_R_P1024TO2047, RMON_R_P_GTE2048,
      RMON_R_OCTETS, IEEE_R_DROP, IEEE_R_FRAME_OK, IEEE_R_CRC, IEEE_R_ALIGN,
      IEEE_R_MACERR, IEEE_R_FDXFC, IEEE_R_OCTETS_OK, RESERVED_17[71], ATCR,
      ATVR, ATOFF, ATPER, ATCOR, ATINC, ATSTMP, RESERVED_18[122], TGSR,
      CHANNEL_TCSR[4], CHANNEL_TCCR[4];
};

#define ENET ((struct ENET_Type *) 0x40138000)

#define ETH_PKT_SIZE 1536  // Max frame size
#define ETH_DESC_CNT 4     // Descriptors count
#define ETH_DS 2           // Descriptor size (words)

#define MG_8BYTE_ALIGNED __attribute__((aligned((8U))))
static uint8_t s_rxbuf[ETH_DESC_CNT][ETH_PKT_SIZE] MG_8BYTE_ALIGNED;
static uint8_t s_txbuf[ETH_DESC_CNT][ETH_PKT_SIZE] MG_8BYTE_ALIGNED;
static uint32_t s_rxdesc[ETH_DESC_CNT][ETH_DS] MG_8BYTE_ALIGNED;
static uint32_t s_txdesc[ETH_DESC_CNT][ETH_DS] MG_8BYTE_ALIGNED;
static uint8_t s_txno;  // Current TX descriptor
static uint8_t s_rxno;  // Current RX descriptor

static struct mg_tcpip_if *s_ifp;  // MIP interface

static uint16_t eth_read_phy(uint8_t addr, uint8_t reg) {
  ENET->MMFR = MG_BIT(30) |  // Start of frame delimiter
               MG_BIT(29) |  // Opcode
               ((addr & 0x1f) << 23) | ((reg & 0x1f) << 18) | MG_BIT(17);
  while ((ENET->EIR & MG_BIT(23)) == 0) (void) 0;
  ENET->EIR |= MG_BIT(23);
  return ENET->MMFR & 0xffff;
}

static void eth_write_phy(uint8_t addr, uint8_t reg, uint16_t val) {
  ENET->MMFR = MG_BIT(30) |  // Start of frame delimiter
               MG_BIT(28) |  // Opcode
               ((addr & 0x1f) << 23) | ((reg & 0x1f) << 18) | MG_BIT(17) | val;
  while ((ENET->EIR & MG_BIT(23)) == 0) (void) 0;
  ENET->EIR |= MG_BIT(23);
}

static bool mg_tcpip_driver_rw612_init(struct mg_tcpip_if *ifp) {
  struct mg_tcpip_driver_rw612_data *d =
      (struct mg_tcpip_driver_rw612_data *) ifp->driver_data;
  s_ifp = ifp;
  ENET->MSCR = ((d->mdc_cr & 0x3f) << 1) | ((d->mdc_holdtime & 7) << 8);
  struct mg_phy phy = {eth_read_phy, eth_write_phy};
  mg_phy_init(&phy, d->phy_addr, 0);
  ENET->ECR |= MG_BIT(0);  // reset ETH

  // initialize descriptors
  for (int i = 0; i < ETH_DESC_CNT; i++) {
    s_rxdesc[i][1] = (uint32_t) s_rxbuf[i];
    s_rxdesc[i][0] = MG_BIT(31);  // OWN
    if (i == ETH_DESC_CNT - 1) {
      s_rxdesc[i][0] |= MG_BIT(29);  // mark last descriptor
    }
    s_txdesc[i][1] = (uint32_t) s_txbuf[i];
    if (i == ETH_DESC_CNT - 1) {
      s_txdesc[i][0] |= MG_BIT(29);  // mark last descriptor
    }
  }

  ENET->RCR = (ENET->RCR & (0xffff << 16)) | MG_BIT(14) | MG_BIT(8) | MG_BIT(2);
  ENET->TCR = MG_BIT(2);  // full duplex
  ENET->TDSR = (uint32_t) &s_txdesc[0][0];
  ENET->RDSR = (uint32_t) &s_rxdesc[0][0];
  ENET->MRBR = ETH_PKT_SIZE;
  ENET->PALR =
      ifp->mac[0] << 24 | ifp->mac[1] << 16 | ifp->mac[2] << 8 | ifp->mac[3];
  ENET->PAUR |= (ifp->mac[4] << 24 | ifp->mac[5] << 16);
  ENET->MSCR = ((d->mdc_cr & 0x3f) << 1) | ((d->mdc_holdtime & 7) << 8);
  ENET->EIMR = MG_BIT(25);             // Enable RX interrupt
  ENET->ECR |= MG_BIT(8) | MG_BIT(1);  // DBSWP, Enable
  ENET->RDAR = 0;                      // activate RX descriptors ring
  return true;
}

static size_t mg_tcpip_driver_rw612_tx(const void *buf, size_t len,
                                       struct mg_tcpip_if *ifp) {
  if (len > sizeof(s_txbuf[s_txno])) {
    MG_ERROR(("Frame too big, %ld", (long) len));
    len = 0;  // Frame is too big
  } else if (((s_txdesc[s_txno][0] & MG_BIT(31)) != 0)) {
    ifp->nerr++;
    MG_ERROR(("No free descriptors"));
    len = 0;  // All descriptors are busy, fail
  } else {
    memcpy(s_txbuf[s_txno], buf, len);
    s_txdesc[s_txno][0] = len | MG_BIT(27) | MG_BIT(26);  // last buffer, crc
    if (s_txno == ETH_DESC_CNT - 1) {
      s_txdesc[s_txno][0] |= MG_BIT(29);  // wrap
    }
    s_txdesc[s_txno][0] |= MG_BIT(31);  // release ownership
    MG_DSB();
    ENET->TDAR = 0;
    // MG_INFO(("s_txdesc[%d][0]: 0x%x", s_txno, s_txdesc[s_txno][0]));
    if (++s_txno >= ETH_DESC_CNT) s_txno = 0;
  }

  return len;
}

static bool mg_tcpip_driver_rw612_up(struct mg_tcpip_if *ifp) {
  struct mg_tcpip_driver_rw612_data *d =
      (struct mg_tcpip_driver_rw612_data *) ifp->driver_data;
  uint8_t speed = MG_PHY_SPEED_10M;
  bool up = false, full_duplex = false;
  struct mg_phy phy = {eth_read_phy, eth_write_phy};
  up = mg_phy_up(&phy, d->phy_addr, &full_duplex, &speed);
  if ((ifp->state == MG_TCPIP_STATE_DOWN) && up) {  // link state just went up
    // tmp = reg with flags set to the most likely situation: 100M full-duplex
    // if(link is slow or half) set flags otherwise
    // reg = tmp
    if (speed == MG_PHY_SPEED_100M && (ENET->RCR & MG_BIT(9))) {
      ENET->RCR &= ~MG_BIT(9);
    } else if (speed == MG_PHY_SPEED_10M && (ENET->RCR & MG_BIT(9)) == 0) {
      ENET->RCR |= MG_BIT(9);
    }
    if (full_duplex && (ENET->TCR & MG_BIT(2)) == 0) {
      ENET->ECR &= ~MG_BIT(1);
      ENET->TCR |= MG_BIT(2);
      ENET->ECR |= MG_BIT(1);
    } else if (!full_duplex && (ENET->TCR & MG_BIT(2))) {
      ENET->ECR &= ~MG_BIT(1);
      ENET->TCR &= ~MG_BIT(2);
      ENET->ECR |= MG_BIT(1);
    }
    MG_INFO(("Link is %uM %s-duplex",
             speed == MG_PHY_SPEED_10M
                 ? 10
                 : (speed == MG_PHY_SPEED_100M ? 100 : 1000),
             full_duplex ? "full" : "half"));
  }
  return up;
}

void ENET_IRQHandler(void) {
  if (ENET->EIR & MG_BIT(25)) {
    ENET->EIR = MG_BIT(25); // Ack RX
    for (uint32_t i = 0; i < 10; i++) {  // read as they arrive but not forever
      if ((s_rxdesc[s_rxno][0] & MG_BIT(31)) != 0) break;  // exit when done
      // skip partial/errored frames
      if ((s_rxdesc[s_rxno][0] & MG_BIT(27)) &&
          !(s_rxdesc[s_rxno][0] &
            (MG_BIT(21) | MG_BIT(20) | MG_BIT(18) | MG_BIT(17) | MG_BIT(16)))) {
        size_t len = s_rxdesc[s_rxno][0] & 0xffff;
        mg_tcpip_qwrite(s_rxbuf[s_rxno], len, s_ifp);
        s_rxdesc[s_rxno][0] |= MG_BIT(31);  // OWN bit: handle control to DMA
        MG_DSB();
        ENET->RDAR = 0;
        if (++s_rxno >= ETH_DESC_CNT) s_rxno = 0;
      }
    }
  }
}

struct mg_tcpip_driver mg_tcpip_driver_rw612 = {mg_tcpip_driver_rw612_init,
                                                mg_tcpip_driver_rw612_tx, NULL,
                                                mg_tcpip_driver_rw612_up};
#endif

#ifdef MG_ENABLE_LINES
#line 1 "src/drivers/same54.c"
#endif


#if MG_ENABLE_TCPIP && defined(MG_ENABLE_DRIVER_SAME54) && \
    MG_ENABLE_DRIVER_SAME54

#include <sam.h>

#define ETH_PKT_SIZE 1536  // Max frame size
#define ETH_DESC_CNT 4     // Descriptors count
#define ETH_DS 2           // Descriptor size (words)

static uint8_t s_rxbuf[ETH_DESC_CNT][ETH_PKT_SIZE];
static uint8_t s_txbuf[ETH_DESC_CNT][ETH_PKT_SIZE];
static uint32_t s_rxdesc[ETH_DESC_CNT][ETH_DS];  // RX descriptors
static uint32_t s_txdesc[ETH_DESC_CNT][ETH_DS];  // TX descriptors
static uint8_t s_txno;                           // Current TX descriptor
static uint8_t s_rxno;                           // Current RX descriptor

static struct mg_tcpip_if *s_ifp;  // MIP interface
enum { MG_PHY_ADDR = 0, MG_PHYREG_BCR = 0, MG_PHYREG_BSR = 1 };

#define MG_PHYREGBIT_BCR_DUPLEX_MODE MG_BIT(8)
#define MG_PHYREGBIT_BCR_SPEED MG_BIT(13)
#define MG_PHYREGBIT_BSR_LINK_STATUS MG_BIT(2)

static uint16_t eth_read_phy(uint8_t addr, uint8_t reg) {
  GMAC_REGS->GMAC_MAN = GMAC_MAN_CLTTO_Msk |
                        GMAC_MAN_OP(2) |  // Setting the read operation
                        GMAC_MAN_WTN(2) | GMAC_MAN_PHYA(addr) |  // PHY address
                        GMAC_MAN_REGA(reg);  // Setting the register
  while (!(GMAC_REGS->GMAC_NSR & GMAC_NSR_IDLE_Msk)) (void) 0;
  return GMAC_REGS->GMAC_MAN & GMAC_MAN_DATA_Msk;  // Getting the read value
}

#if 0
static void eth_write_phy(uint8_t addr, uint8_t reg, uint16_t val) {
  GMAC_REGS->GMAC_MAN = GMAC_MAN_CLTTO_Msk | GMAC_MAN_OP(1) |   // Setting the write operation
                        GMAC_MAN_WTN(2) | GMAC_MAN_PHYA(addr) | // PHY address
                        GMAC_MAN_REGA(reg) | GMAC_MAN_DATA(val);  // Setting the register
  while (!(GMAC_REGS->GMAC_NSR & GMAC_NSR_IDLE_Msk)); // Waiting until the write op is complete
}
#endif

int get_clock_rate(struct mg_tcpip_driver_same54_data *d) {
  if (d && d->mdc_cr >= 0 && d->mdc_cr <= 5) {
    return d->mdc_cr;
  } else {
    // get MCLK from GCLK_GENERATOR 0
    uint32_t div = 512;
    uint32_t mclk;
    if (!(GCLK_REGS->GCLK_GENCTRL[0] & GCLK_GENCTRL_DIVSEL_Msk)) {
      div = ((GCLK_REGS->GCLK_GENCTRL[0] & 0x00FF0000) >> 16);
      if (div == 0) div = 1;
    }
    switch (GCLK_REGS->GCLK_GENCTRL[0] & GCLK_GENCTRL_SRC_Msk) {
      case GCLK_GENCTRL_SRC_XOSC0_Val:
        mclk = 32000000UL; /* 32MHz */
        break;
      case GCLK_GENCTRL_SRC_XOSC1_Val:
        mclk = 32000000UL; /* 32MHz */
        break;
      case GCLK_GENCTRL_SRC_OSCULP32K_Val:
        mclk = 32000UL;
        break;
      case GCLK_GENCTRL_SRC_XOSC32K_Val:
        mclk = 32000UL;
        break;
      case GCLK_GENCTRL_SRC_DFLL_Val:
        mclk = 48000000UL; /* 48MHz */
        break;
      case GCLK_GENCTRL_SRC_DPLL0_Val:
        mclk = 200000000UL; /* 200MHz */
        break;
      case GCLK_GENCTRL_SRC_DPLL1_Val:
        mclk = 200000000UL; /* 200MHz */
        break;
      default:
        mclk = 200000000UL; /* 200MHz */
    }

    mclk /= div;
    uint8_t crs[] = {0, 1, 2, 3, 4, 5};            // GMAC->NCFGR::CLK values
    uint8_t dividers[] = {8, 16, 32, 48, 64, 96};  // Respective CLK dividers
    for (int i = 0; i < 6; i++) {
      if (mclk / dividers[i] <= 2375000UL /* 2.5MHz - 5% */) {
        return crs[i];
      }
    }

    return 5;
  }
}

static bool mg_tcpip_driver_same54_init(struct mg_tcpip_if *ifp) {
  struct mg_tcpip_driver_same54_data *d =
      (struct mg_tcpip_driver_same54_data *) ifp->driver_data;
  s_ifp = ifp;

  MCLK_REGS->MCLK_APBCMASK |= MCLK_APBCMASK_GMAC_Msk;
  MCLK_REGS->MCLK_AHBMASK |= MCLK_AHBMASK_GMAC_Msk;
  GMAC_REGS->GMAC_NCFGR = GMAC_NCFGR_CLK(get_clock_rate(d));  // Set MDC divider
  GMAC_REGS->GMAC_NCR = 0;                                    // Disable RX & TX
  GMAC_REGS->GMAC_NCR |= GMAC_NCR_MPE_Msk;  // Enable MDC & MDIO

  for (int i = 0; i < ETH_DESC_CNT; i++) {   // Init TX descriptors
    s_txdesc[i][0] = (uint32_t) s_txbuf[i];  // Point to data buffer
    s_txdesc[i][1] = MG_BIT(31);             // OWN bit
  }
  s_txdesc[ETH_DESC_CNT - 1][1] |= MG_BIT(30);  // Last tx descriptor - wrap

  GMAC_REGS->GMAC_DCFGR = GMAC_DCFGR_DRBS(0x18)  // DMA recv buf 1536
                          | GMAC_DCFGR_RXBMS(GMAC_DCFGR_RXBMS_FULL_Val) |
                          GMAC_DCFGR_TXPBMS(1);  // See #2487
  for (int i = 0; i < ETH_DESC_CNT; i++) {       // Init RX descriptors
    s_rxdesc[i][0] = (uint32_t) s_rxbuf[i];      // Address of the data buffer
    s_rxdesc[i][1] = 0;                          // Clear status
  }
  s_rxdesc[ETH_DESC_CNT - 1][0] |= MG_BIT(1);  // Last rx descriptor - wrap

  GMAC_REGS->GMAC_TBQB = (uint32_t) s_txdesc;  // about the descriptor addresses
  GMAC_REGS->GMAC_RBQB = (uint32_t) s_rxdesc;  // Let the controller know

  GMAC_REGS->SA[0].GMAC_SAB =
      MG_U32(ifp->mac[3], ifp->mac[2], ifp->mac[1], ifp->mac[0]);
  GMAC_REGS->SA[0].GMAC_SAT = MG_U32(0, 0, ifp->mac[5], ifp->mac[4]);

  GMAC_REGS->GMAC_UR &= ~GMAC_UR_MII_Msk;  // Disable MII, use RMII
  GMAC_REGS->GMAC_NCFGR |= GMAC_NCFGR_MAXFS_Msk | GMAC_NCFGR_MTIHEN_Msk |
                           GMAC_NCFGR_EFRHD_Msk | GMAC_NCFGR_CAF_Msk;
  GMAC_REGS->GMAC_TSR = GMAC_TSR_HRESP_Msk | GMAC_TSR_UND_Msk |
                        GMAC_TSR_TXCOMP_Msk | GMAC_TSR_TFC_Msk |
                        GMAC_TSR_TXGO_Msk | GMAC_TSR_RLE_Msk |
                        GMAC_TSR_COL_Msk | GMAC_TSR_UBR_Msk;
  GMAC_REGS->GMAC_RSR = GMAC_RSR_HNO_Msk | GMAC_RSR_RXOVR_Msk |
                        GMAC_RSR_REC_Msk | GMAC_RSR_BNA_Msk;
  GMAC_REGS->GMAC_IDR = ~0U;  // Disable interrupts, then enable required
  GMAC_REGS->GMAC_IER = GMAC_IER_HRESP_Msk | GMAC_IER_ROVR_Msk |
                        GMAC_IER_TCOMP_Msk | GMAC_IER_TFC_Msk |
                        GMAC_IER_RLEX_Msk | GMAC_IER_TUR_Msk |
                        GMAC_IER_RXUBR_Msk | GMAC_IER_RCOMP_Msk;
  GMAC_REGS->GMAC_NCR |= GMAC_NCR_TXEN_Msk | GMAC_NCR_RXEN_Msk;
  NVIC_EnableIRQ(GMAC_IRQn);

  return true;
}

static size_t mg_tcpip_driver_same54_tx(const void *buf, size_t len,
                                        struct mg_tcpip_if *ifp) {
  if (len > sizeof(s_txbuf[s_txno])) {
    MG_ERROR(("Frame too big, %ld", (long) len));
    len = 0;  // Frame is too big
  } else if ((s_txdesc[s_txno][1] & MG_BIT(31)) == 0) {
    ifp->nerr++;
    MG_ERROR(("No free descriptors"));
    len = 0;  // All descriptors are busy, fail
  } else {
    uint32_t status = len | MG_BIT(15);  // Frame length, last chunk
    if (s_txno == ETH_DESC_CNT - 1) status |= MG_BIT(30);  // wrap
    memcpy(s_txbuf[s_txno], buf, len);                     // Copy data
    s_txdesc[s_txno][1] = status;
    if (++s_txno >= ETH_DESC_CNT) s_txno = 0;
  }
  __DSB();  // Ensure descriptors have been written
  GMAC_REGS->GMAC_NCR |= GMAC_NCR_TSTART_Msk;  // Enable transmission
  return len;
}

static bool mg_tcpip_driver_same54_poll(struct mg_tcpip_if *ifp, bool s1) {
  if (s1) {
    uint16_t bsr = eth_read_phy(MG_PHY_ADDR, MG_PHYREG_BSR);
    bool up = bsr & MG_PHYREGBIT_BSR_LINK_STATUS ? 1 : 0;

    // If PHY is ready, update NCFGR accordingly
    if (ifp->state == MG_TCPIP_STATE_DOWN && up) {
      uint16_t bcr = eth_read_phy(MG_PHY_ADDR, MG_PHYREG_BCR);
      bool fd = bcr & MG_PHYREGBIT_BCR_DUPLEX_MODE ? 1 : 0;
      bool spd = bcr & MG_PHYREGBIT_BCR_SPEED ? 1 : 0;
      GMAC_REGS->GMAC_NCFGR = (GMAC_REGS->GMAC_NCFGR &
                               ~(GMAC_NCFGR_SPD_Msk | MG_PHYREGBIT_BCR_SPEED)) |
                              GMAC_NCFGR_SPD(spd) | GMAC_NCFGR_FD(fd);
    }
  }
  return false;
}

void GMAC_Handler(void);
void GMAC_Handler(void) {
  uint32_t isr = GMAC_REGS->GMAC_ISR;
  uint32_t rsr = GMAC_REGS->GMAC_RSR;
  uint32_t tsr = GMAC_REGS->GMAC_TSR;
  if (isr & GMAC_ISR_RCOMP_Msk) {
    if (rsr & GMAC_ISR_RCOMP_Msk) {
      for (uint8_t i = 0; i < ETH_DESC_CNT; i++) {
        if ((s_rxdesc[s_rxno][0] & MG_BIT(0)) == 0) break;
        size_t len = s_rxdesc[s_rxno][1] & (MG_BIT(13) - 1);
        mg_tcpip_qwrite(s_rxbuf[s_rxno], len, s_ifp);
        s_rxdesc[s_rxno][0] &= ~MG_BIT(0);  // Disown
        if (++s_rxno >= ETH_DESC_CNT) s_rxno = 0;
      }
    }
  }

  if ((tsr & (GMAC_TSR_HRESP_Msk | GMAC_TSR_UND_Msk | GMAC_TSR_TXCOMP_Msk |
              GMAC_TSR_TFC_Msk | GMAC_TSR_TXGO_Msk | GMAC_TSR_RLE_Msk |
              GMAC_TSR_COL_Msk | GMAC_TSR_UBR_Msk)) != 0) {
    // MG_INFO((" --> %#x %#x", s_txdesc[s_txno][1], tsr));
    if (!(s_txdesc[s_txno][1] & MG_BIT(31))) s_txdesc[s_txno][1] |= MG_BIT(31);
  }

  GMAC_REGS->GMAC_RSR = rsr;
  GMAC_REGS->GMAC_TSR = tsr;
}

struct mg_tcpip_driver mg_tcpip_driver_same54 = {
    mg_tcpip_driver_same54_init, mg_tcpip_driver_same54_tx, NULL,
    mg_tcpip_driver_same54_poll};
#endif

#ifdef MG_ENABLE_LINES
#line 1 "src/drivers/stm32f.c"
#endif


#if MG_ENABLE_TCPIP && defined(MG_ENABLE_DRIVER_STM32F) && \
    MG_ENABLE_DRIVER_STM32F
struct stm32f_eth {
  volatile uint32_t MACCR, MACFFR, MACHTHR, MACHTLR, MACMIIAR, MACMIIDR, MACFCR,
      MACVLANTR, RESERVED0[2], MACRWUFFR, MACPMTCSR, RESERVED1, MACDBGR, MACSR,
      MACIMR, MACA0HR, MACA0LR, MACA1HR, MACA1LR, MACA2HR, MACA2LR, MACA3HR,
      MACA3LR, RESERVED2[40], MMCCR, MMCRIR, MMCTIR, MMCRIMR, MMCTIMR,
      RESERVED3[14], MMCTGFSCCR, MMCTGFMSCCR, RESERVED4[5], MMCTGFCR,
      RESERVED5[10], MMCRFCECR, MMCRFAECR, RESERVED6[10], MMCRGUFCR,
      RESERVED7[334], PTPTSCR, PTPSSIR, PTPTSHR, PTPTSLR, PTPTSHUR, PTPTSLUR,
      PTPTSAR, PTPTTHR, PTPTTLR, RESERVED8, PTPTSSR, PTPPPSCR, RESERVED9[564],
      DMABMR, DMATPDR, DMARPDR, DMARDLAR, DMATDLAR, DMASR, DMAOMR, DMAIER,
      DMAMFBOCR, DMARSWTR, RESERVED10[8], DMACHTDR, DMACHRDR, DMACHTBAR,
      DMACHRBAR;
};
#undef ETH
#define ETH ((struct stm32f_eth *) (uintptr_t) 0x40028000)

#define ETH_PKT_SIZE 1540  // Max frame size
#define ETH_DESC_CNT 4     // Descriptors count
#define ETH_DS 4           // Descriptor size (words)

static uint32_t s_rxdesc[ETH_DESC_CNT][ETH_DS];      // RX descriptors
static uint32_t s_txdesc[ETH_DESC_CNT][ETH_DS];      // TX descriptors
static uint8_t s_rxbuf[ETH_DESC_CNT][ETH_PKT_SIZE];  // RX ethernet buffers
static uint8_t s_txbuf[ETH_DESC_CNT][ETH_PKT_SIZE];  // TX ethernet buffers
static uint8_t s_txno;                               // Current TX descriptor
static uint8_t s_rxno;                               // Current RX descriptor

static struct mg_tcpip_if *s_ifp;  // MIP interface

static uint16_t eth_read_phy(uint8_t addr, uint8_t reg) {
  ETH->MACMIIAR &= (7 << 2);
  ETH->MACMIIAR |= ((uint32_t) addr << 11) | ((uint32_t) reg << 6);
  ETH->MACMIIAR |= MG_BIT(0);
  while (ETH->MACMIIAR & MG_BIT(0)) (void) 0;
  return ETH->MACMIIDR & 0xffff;
}

static void eth_write_phy(uint8_t addr, uint8_t reg, uint16_t val) {
  ETH->MACMIIDR = val;
  ETH->MACMIIAR &= (7 << 2);
  ETH->MACMIIAR |= ((uint32_t) addr << 11) | ((uint32_t) reg << 6) | MG_BIT(1);
  ETH->MACMIIAR |= MG_BIT(0);
  while (ETH->MACMIIAR & MG_BIT(0)) (void) 0;
}

static uint32_t get_hclk(void) {
  struct rcc {
    volatile uint32_t CR, PLLCFGR, CFGR;
  } *rcc = (struct rcc *) 0x40023800;
  uint32_t clk = 0, hsi = 16000000 /* 16 MHz */, hse = 8000000 /* 8MHz */;

  if (rcc->CFGR & (1 << 2)) {
    clk = hse;
  } else if (rcc->CFGR & (1 << 3)) {
    uint32_t vco, m, n, p;
    m = (rcc->PLLCFGR & (0x3f << 0)) >> 0;
    n = (rcc->PLLCFGR & (0x1ff << 6)) >> 6;
    p = (((rcc->PLLCFGR & (3 << 16)) >> 16) + 1) * 2;
    clk = (rcc->PLLCFGR & (1 << 22)) ? hse : hsi;
    vco = (uint32_t) ((uint64_t) clk * n / m);
    clk = vco / p;
  } else {
    clk = hsi;
  }
  uint32_t hpre = (rcc->CFGR & (15 << 4)) >> 4;
  if (hpre < 8) return clk;

  uint8_t ahbptab[8] = {1, 2, 3, 4, 6, 7, 8, 9};  // log2(div)
  return ((uint32_t) clk) >> ahbptab[hpre - 8];
}

//  Guess CR from HCLK. MDC clock is generated from HCLK (AHB); as per 802.3,
//  it must not exceed 2.5MHz As the AHB clock can be (and usually is) derived
//  from the HSI (internal RC), and it can go above specs, the datasheets
//  specify a range of frequencies and activate one of a series of dividers to
//  keep the MDC clock safely below 2.5MHz. We guess a divider setting based on
//  HCLK with a +5% drift. If the user uses a different clock from our
//  defaults, needs to set the macros on top Valid for STM32F74xxx/75xxx
//  (38.8.1) and STM32F42xxx/43xxx (33.8.1) (both 4.5% worst case drift)
static int guess_mdc_cr(void) {
  uint8_t crs[] = {2, 3, 0, 1, 4, 5};          // ETH->MACMIIAR::CR values
  uint8_t div[] = {16, 26, 42, 62, 102, 124};  // Respective HCLK dividers
  uint32_t hclk = get_hclk();                  // Guess system HCLK
  int result = -1;                             // Invalid CR value
  if (hclk < 25000000) {
    MG_ERROR(("HCLK too low"));
  } else {
    for (int i = 0; i < 6; i++) {
      if (hclk / div[i] <= 2375000UL /* 2.5MHz - 5% */) {
        result = crs[i];
        break;
      }
    }
    if (result < 0) MG_ERROR(("HCLK too high"));
  }
  MG_DEBUG(("HCLK: %u, CR: %d", hclk, result));
  return result;
}

static bool mg_tcpip_driver_stm32f_init(struct mg_tcpip_if *ifp) {
  struct mg_tcpip_driver_stm32f_data *d =
      (struct mg_tcpip_driver_stm32f_data *) ifp->driver_data;
  uint8_t phy_addr = d == NULL ? 0 : d->phy_addr;
  s_ifp = ifp;

  // Init RX descriptors
  for (int i = 0; i < ETH_DESC_CNT; i++) {
    s_rxdesc[i][0] = MG_BIT(31);                         // Own
    s_rxdesc[i][1] = sizeof(s_rxbuf[i]) | MG_BIT(14);    // 2nd address chained
    s_rxdesc[i][2] = (uint32_t) (uintptr_t) s_rxbuf[i];  // Point to data buffer
    s_rxdesc[i][3] =
        (uint32_t) (uintptr_t) s_rxdesc[(i + 1) % ETH_DESC_CNT];  // Chain
  }

  // Init TX descriptors
  for (int i = 0; i < ETH_DESC_CNT; i++) {
    s_txdesc[i][2] = (uint32_t) (uintptr_t) s_txbuf[i];  // Buf pointer
    s_txdesc[i][3] =
        (uint32_t) (uintptr_t) s_txdesc[(i + 1) % ETH_DESC_CNT];  // Chain
  }

  ETH->DMABMR |= MG_BIT(0);                         // Software reset
  while ((ETH->DMABMR & MG_BIT(0)) != 0) (void) 0;  // Wait until done

  // Set MDC clock divider. If user told us the value, use it. Otherwise, guess
  int cr = (d == NULL || d->mdc_cr < 0) ? guess_mdc_cr() : d->mdc_cr;
  ETH->MACMIIAR = ((uint32_t) cr & 7) << 2;

  // NOTE(cpq): we do not use extended descriptor bit 7, and do not use
  // hardware checksum. Therefore, descriptor size is 4, not 8
  // ETH->DMABMR = MG_BIT(13) | MG_BIT(16) | MG_BIT(22) | MG_BIT(23) |
  // MG_BIT(25);
  ETH->MACIMR = MG_BIT(3) | MG_BIT(9);  // Mask timestamp & PMT IT
  ETH->MACFCR = MG_BIT(7);              // Disable zero quarta pause
  // ETH->MACFFR = MG_BIT(31);                            // Receive all
  struct mg_phy phy = {eth_read_phy, eth_write_phy};
  mg_phy_init(&phy, phy_addr, MG_PHY_CLOCKS_MAC);
  ETH->DMARDLAR = (uint32_t) (uintptr_t) s_rxdesc;  // RX descriptors
  ETH->DMATDLAR = (uint32_t) (uintptr_t) s_txdesc;  // RX descriptors
  ETH->DMAIER = MG_BIT(6) | MG_BIT(16);             // RIE, NISE
  ETH->MACCR =
      MG_BIT(2) | MG_BIT(3) | MG_BIT(11) | MG_BIT(14);  // RE, TE, Duplex, Fast
  ETH->DMAOMR =
      MG_BIT(1) | MG_BIT(13) | MG_BIT(21) | MG_BIT(25);  // SR, ST, TSF, RSF

  // MAC address filtering
  ETH->MACA0HR = ((uint32_t) ifp->mac[5] << 8U) | ifp->mac[4];
  ETH->MACA0LR = (uint32_t) (ifp->mac[3] << 24) |
                 ((uint32_t) ifp->mac[2] << 16) |
                 ((uint32_t) ifp->mac[1] << 8) | ifp->mac[0];
  return true;
}

static size_t mg_tcpip_driver_stm32f_tx(const void *buf, size_t len,
                                        struct mg_tcpip_if *ifp) {
  if (len > sizeof(s_txbuf[s_txno])) {
    MG_ERROR(("Frame too big, %ld", (long) len));
    len = 0;  // Frame is too big
  } else if ((s_txdesc[s_txno][0] & MG_BIT(31))) {
    ifp->nerr++;
    MG_ERROR(("No free descriptors"));
    // printf("D0 %lx SR %lx\n", (long) s_txdesc[0][0], (long) ETH->DMASR);
    len = 0;  // All descriptors are busy, fail
  } else {
    memcpy(s_txbuf[s_txno], buf, len);                           // Copy data
    s_txdesc[s_txno][1] = (uint32_t) len;                        // Set data len
    s_txdesc[s_txno][0] = MG_BIT(20) | MG_BIT(28) | MG_BIT(29);  // Chain,FS,LS
    s_txdesc[s_txno][0] |= MG_BIT(31);  // Set OWN bit - let DMA take over
    if (++s_txno >= ETH_DESC_CNT) s_txno = 0;
  }
  MG_DSB();                            // ensure descriptors have been written
  ETH->DMASR = MG_BIT(2) | MG_BIT(5);  // Clear any prior TBUS/TUS
  ETH->DMATPDR = 0;                    // and resume
  return len;
}

static bool mg_tcpip_driver_stm32f_poll(struct mg_tcpip_if *ifp, bool s1) {
  if (!s1) return false;
  struct mg_tcpip_driver_stm32f_data *d =
      (struct mg_tcpip_driver_stm32f_data *) ifp->driver_data;
  uint8_t phy_addr = d == NULL ? 0 : d->phy_addr;
  uint8_t speed = MG_PHY_SPEED_10M;
  bool up = false, full_duplex = false;
  struct mg_phy phy = {eth_read_phy, eth_write_phy};
  up = mg_phy_up(&phy, phy_addr, &full_duplex, &speed);
  if ((ifp->state == MG_TCPIP_STATE_DOWN) && up) {  // link state just went up
    // tmp = reg with flags set to the most likely situation: 100M full-duplex
    // if(link is slow or half) set flags otherwise
    // reg = tmp
    uint32_t maccr = ETH->MACCR | MG_BIT(14) | MG_BIT(11);  // 100M, Full-duplex
    if (speed == MG_PHY_SPEED_10M) maccr &= ~MG_BIT(14);    // 10M
    if (full_duplex == false) maccr &= ~MG_BIT(11);         // Half-duplex
    ETH->MACCR = maccr;  // IRQ handler does not fiddle with this register
    MG_DEBUG(("Link is %uM %s-duplex", maccr & MG_BIT(14) ? 100 : 10,
              maccr & MG_BIT(11) ? "full" : "half"));
  }
  return up;
}

#ifdef __riscv
__attribute__((interrupt()))  // For RISCV CH32V307, which share the same MAC
#endif
void ETH_IRQHandler(void);
void ETH_IRQHandler(void) {
  if (ETH->DMASR & MG_BIT(6)) {           // Frame received, loop
    ETH->DMASR = MG_BIT(16) | MG_BIT(6);  // Clear flag
    for (uint32_t i = 0; i < 10; i++) {   // read as they arrive but not forever
      if (s_rxdesc[s_rxno][0] & MG_BIT(31)) break;  // exit when done
      if (((s_rxdesc[s_rxno][0] & (MG_BIT(8) | MG_BIT(9))) ==
           (MG_BIT(8) | MG_BIT(9))) &&
          !(s_rxdesc[s_rxno][0] & MG_BIT(15))) {  // skip partial/errored frames
        uint32_t len = ((s_rxdesc[s_rxno][0] >> 16) & (MG_BIT(14) - 1));
        //  printf("%lx %lu %lx %.8lx\n", s_rxno, len, s_rxdesc[s_rxno][0],
        //  ETH->DMASR);
        mg_tcpip_qwrite(s_rxbuf[s_rxno], len > 4 ? len - 4 : len, s_ifp);
      }
      s_rxdesc[s_rxno][0] = MG_BIT(31);
      if (++s_rxno >= ETH_DESC_CNT) s_rxno = 0;
    }
  }
  // Cleanup flags
  ETH->DMASR = MG_BIT(16)    // NIS, normal interrupt summary
               | MG_BIT(7);  // Clear possible RBUS while processing
  ETH->DMARPDR = 0;          // and resume RX
}

struct mg_tcpip_driver mg_tcpip_driver_stm32f = {
    mg_tcpip_driver_stm32f_init, mg_tcpip_driver_stm32f_tx, NULL,
    mg_tcpip_driver_stm32f_poll};
#endif

#ifdef MG_ENABLE_LINES
#line 1 "src/drivers/stm32h.c"
#endif


#if MG_ENABLE_TCPIP && (MG_ENABLE_DRIVER_STM32H || MG_ENABLE_DRIVER_MCXN)
// STM32H: vendor modded single-queue Synopsys v4.2
// MCXNx4x: dual-queue Synopsys v5.2
// RT1170 ENET_QOS: quad-queue Synopsys v5.1
struct synopsys_enet_qos {
  volatile uint32_t MACCR, MACECR, MACPFR, MACWTR, MACHT0R, MACHT1R,
      RESERVED1[14], MACVTR, RESERVED2, MACVHTR, RESERVED3, MACVIR, MACIVIR,
      RESERVED4[2], MACTFCR, RESERVED5[7], MACRFCR, RESERVED6[7], MACISR,
      MACIER, MACRXTXSR, RESERVED7, MACPCSR, MACRWKPFR, RESERVED8[2], MACLCSR,
      MACLTCR, MACLETR, MAC1USTCR, RESERVED9[12], MACVR, MACDR, RESERVED10,
      MACHWF0R, MACHWF1R, MACHWF2R, RESERVED11[54], MACMDIOAR, MACMDIODR,
      RESERVED12[2], MACARPAR, RESERVED13[59], MACA0HR, MACA0LR, MACA1HR,
      MACA1LR, MACA2HR, MACA2LR, MACA3HR, MACA3LR, RESERVED14[248], MMCCR,
      MMCRIR, MMCTIR, MMCRIMR, MMCTIMR, RESERVED15[14], MMCTSCGPR, MMCTMCGPR,
      RESERVED16[5], MMCTPCGR, RESERVED17[10], MMCRCRCEPR, MMCRAEPR,
      RESERVED18[10], MMCRUPGR, RESERVED19[9], MMCTLPIMSTR, MMCTLPITCR,
      MMCRLPIMSTR, MMCRLPITCR, RESERVED20[65], MACL3L4C0R, MACL4A0R,
      RESERVED21[2], MACL3A0R0R, MACL3A1R0R, MACL3A2R0R, MACL3A3R0R,
      RESERVED22[4], MACL3L4C1R, MACL4A1R, RESERVED23[2], MACL3A0R1R,
      MACL3A1R1R, MACL3A2R1R, MACL3A3R1R, RESERVED24[108], MACTSCR, MACSSIR,
      MACSTSR, MACSTNR, MACSTSUR, MACSTNUR, MACTSAR, RESERVED25, MACTSSR,
      RESERVED26[3], MACTTSSNR, MACTTSSSR, RESERVED27[2], MACACR, RESERVED28,
      MACATSNR, MACATSSR, MACTSIACR, MACTSEACR, MACTSICNR, MACTSECNR,
      RESERVED29[4], MACPPSCR, RESERVED30[3], MACPPSTTSR, MACPPSTTNR, MACPPSIR,
      MACPPSWR, RESERVED31[12], MACPOCR, MACSPI0R, MACSPI1R, MACSPI2R, MACLMIR,
      RESERVED32[11], MTLOMR, RESERVED33[7], MTLISR, RESERVED34[55], MTLTQOMR,
      MTLTQUR, MTLTQDR, RESERVED35[8], MTLQICSR, MTLRQOMR, MTLRQMPOCR, MTLRQDR,
      RESERVED36[177], DMAMR, DMASBMR, DMAISR, DMADSR, RESERVED37[60], DMACCR,
      DMACTCR, DMACRCR, RESERVED38[2], DMACTDLAR, RESERVED39, DMACRDLAR,
      DMACTDTPR, RESERVED40, DMACRDTPR, DMACTDRLR, DMACRDRLR, DMACIER,
      DMACRIWTR, DMACSFCSR, RESERVED41, DMACCATDR, RESERVED42, DMACCARDR,
      RESERVED43, DMACCATBR, RESERVED44, DMACCARBR, DMACSR, RESERVED45[2],
      DMACMFCR;
};
#undef ETH
#if MG_ENABLE_DRIVER_STM32H
#define ETH                                                                \
  ((struct synopsys_enet_qos *) (uintptr_t) (0x40000000UL + 0x00020000UL + \
                                             0x8000UL))
#elif MG_ENABLE_DRIVER_MCXN
#define ETH ((struct synopsys_enet_qos *) (uintptr_t) 0x40100000UL)
#endif

#define ETH_PKT_SIZE 1540  // Max frame size
#define ETH_DESC_CNT 4     // Descriptors count
#define ETH_DS 4           // Descriptor size (words)

static volatile uint32_t s_rxdesc[ETH_DESC_CNT][ETH_DS];  // RX descriptors
static volatile uint32_t s_txdesc[ETH_DESC_CNT][ETH_DS];  // TX descriptors
static uint8_t s_rxbuf[ETH_DESC_CNT][ETH_PKT_SIZE];       // RX ethernet buffers
static uint8_t s_txbuf[ETH_DESC_CNT][ETH_PKT_SIZE];       // TX ethernet buffers
static struct mg_tcpip_if *s_ifp;                         // MIP interface

static uint16_t eth_read_phy(uint8_t addr, uint8_t reg) {
  ETH->MACMDIOAR &= (0xF << 8);
  ETH->MACMDIOAR |= ((uint32_t) addr << 21) | ((uint32_t) reg << 16) | 3 << 2;
  ETH->MACMDIOAR |= MG_BIT(0);
  while (ETH->MACMDIOAR & MG_BIT(0)) (void) 0;
  return (uint16_t) ETH->MACMDIODR;
}

static void eth_write_phy(uint8_t addr, uint8_t reg, uint16_t val) {
  ETH->MACMDIODR = val;
  ETH->MACMDIOAR &= (0xF << 8);
  ETH->MACMDIOAR |= ((uint32_t) addr << 21) | ((uint32_t) reg << 16) | 1 << 2;
  ETH->MACMDIOAR |= MG_BIT(0);
  while (ETH->MACMDIOAR & MG_BIT(0)) (void) 0;
}

static bool mg_tcpip_driver_stm32h_init(struct mg_tcpip_if *ifp) {
  struct mg_tcpip_driver_stm32h_data *d =
      (struct mg_tcpip_driver_stm32h_data *) ifp->driver_data;
  s_ifp = ifp;
  uint8_t phy_addr = d == NULL ? 0 : d->phy_addr;
  uint8_t phy_conf = d == NULL ? MG_PHY_CLOCKS_MAC : d->phy_conf;

  // Init RX descriptors
  for (int i = 0; i < ETH_DESC_CNT; i++) {
    s_rxdesc[i][0] = (uint32_t) (uintptr_t) s_rxbuf[i];  // Point to data buffer
    s_rxdesc[i][3] = MG_BIT(31) | MG_BIT(30) | MG_BIT(24);  // OWN, IOC, BUF1V
  }

  // Init TX descriptors
  for (int i = 0; i < ETH_DESC_CNT; i++) {
    s_txdesc[i][0] = (uint32_t) (uintptr_t) s_txbuf[i];  // Buf pointer
  }

  ETH->DMAMR |= MG_BIT(0);  // Software reset
  for (int i = 0; i < 4; i++)
    (void) 0;  // wait at least 4 clocks before reading
  while ((ETH->DMAMR & MG_BIT(0)) != 0) (void) 0;  // Wait until done

  // Set MDC clock divider. Get user value, else, assume max freq
  int cr = (d == NULL || d->mdc_cr < 0) ? 7 : d->mdc_cr;
  ETH->MACMDIOAR = ((uint32_t) cr & 0xF) << 8;

  // NOTE(scaprile): We do not use timing facilities so the DMA engine does not
  // re-write buffer address
  ETH->DMAMR = 0 << 16;        // use interrupt mode 0 (58.8.1) (reset value)
  ETH->DMASBMR |= MG_BIT(12);  // AAL NOTE(scaprile): is this actually needed
  ETH->MACIER = 0;  // Do not enable additional irq sources (reset value)
  ETH->MACTFCR = MG_BIT(7);  // Disable zero-quanta pause
  // ETH->MACPFR = MG_BIT(31);  // Receive all
  struct mg_phy phy = {eth_read_phy, eth_write_phy};
  mg_phy_init(&phy, phy_addr, phy_conf);
  ETH->DMACRDLAR =
      (uint32_t) (uintptr_t) s_rxdesc;  // RX descriptors start address
  ETH->DMACRDRLR = ETH_DESC_CNT - 1;    // ring length
  ETH->DMACRDTPR =
      (uint32_t) (uintptr_t) &s_rxdesc[ETH_DESC_CNT -
                                       1];  // last valid descriptor address
  ETH->DMACTDLAR =
      (uint32_t) (uintptr_t) s_txdesc;  // TX descriptors start address
  ETH->DMACTDRLR = ETH_DESC_CNT - 1;    // ring length
  ETH->DMACTDTPR =
      (uint32_t) (uintptr_t) s_txdesc;  // first available descriptor address
  ETH->DMACCR = 0;  // DSL = 0 (contiguous descriptor table) (reset value)
#if !MG_ENABLE_DRIVER_STM32H
  MG_SET_BITS(ETH->DMACTCR, 0x3F << 16, MG_BIT(16));
  MG_SET_BITS(ETH->DMACRCR, 0x3F << 16, MG_BIT(16));
#endif
  ETH->DMACIER = MG_BIT(6) | MG_BIT(15);  // RIE, NIE
  ETH->MACCR = MG_BIT(0) | MG_BIT(1) | MG_BIT(13) | MG_BIT(14) |
               MG_BIT(15);  // RE, TE, Duplex, Fast, Reserved
#if MG_ENABLE_DRIVER_STM32H
  ETH->MTLTQOMR |= MG_BIT(1);  // TSF
  ETH->MTLRQOMR |= MG_BIT(5);  // RSF
#else
  ETH->MTLTQOMR |= (7 << 16) | MG_BIT(3) | MG_BIT(1);  // 2KB Q0, TSF
  ETH->MTLRQOMR |= (7 << 20) | MG_BIT(5);              // 2KB Q, RSF
  MG_SET_BITS(ETH->RESERVED6[3], 3, 2);  // Enable RxQ0 (MAC_RXQ_CTRL0)
#endif
  ETH->DMACTCR |= MG_BIT(0);  // ST
  ETH->DMACRCR |= MG_BIT(0);  // SR

  // MAC address filtering
  ETH->MACA0HR = ((uint32_t) ifp->mac[5] << 8U) | ifp->mac[4];
  ETH->MACA0LR = (uint32_t) (ifp->mac[3] << 24) |
                 ((uint32_t) ifp->mac[2] << 16) |
                 ((uint32_t) ifp->mac[1] << 8) | ifp->mac[0];
  return true;
}

static uint32_t s_txno;
static size_t mg_tcpip_driver_stm32h_tx(const void *buf, size_t len,
                                        struct mg_tcpip_if *ifp) {
  if (len > sizeof(s_txbuf[s_txno])) {
    MG_ERROR(("Frame too big, %ld", (long) len));
    len = 0;  // Frame is too big
  } else if ((s_txdesc[s_txno][3] & MG_BIT(31))) {
    ifp->nerr++;
    MG_ERROR(("No free descriptors: %u %08X %08X %08X", s_txno,
              s_txdesc[s_txno][3], ETH->DMACSR, ETH->DMACTCR));
    for (int i = 0; i < ETH_DESC_CNT; i++) MG_ERROR(("%08X", s_txdesc[i][3]));
    len = 0;  // All descriptors are busy, fail
  } else {
    memcpy(s_txbuf[s_txno], buf, len);              // Copy data
    s_txdesc[s_txno][2] = (uint32_t) len;           // Set data len
    s_txdesc[s_txno][3] = MG_BIT(28) | MG_BIT(29);  // FD, LD
    s_txdesc[s_txno][3] |= MG_BIT(31);  // Set OWN bit - let DMA take over
    if (++s_txno >= ETH_DESC_CNT) s_txno = 0;
  }
  ETH->DMACSR |= MG_BIT(2) | MG_BIT(1);  // Clear any prior TBU, TPS
  ETH->DMACTDTPR = (uint32_t) (uintptr_t) &s_txdesc[s_txno];  // and resume
  return len;
  (void) ifp;
}

static bool mg_tcpip_driver_stm32h_poll(struct mg_tcpip_if *ifp, bool s1) {
  if (!s1) return false;
  struct mg_tcpip_driver_stm32h_data *d =
      (struct mg_tcpip_driver_stm32h_data *) ifp->driver_data;
  uint8_t phy_addr = d == NULL ? 0 : d->phy_addr;
  uint8_t speed = MG_PHY_SPEED_10M;
  bool up = false, full_duplex = false;
  struct mg_phy phy = {eth_read_phy, eth_write_phy};
  up = mg_phy_up(&phy, phy_addr, &full_duplex, &speed);
  if ((ifp->state == MG_TCPIP_STATE_DOWN) && up) {  // link state just went up
    // tmp = reg with flags set to the most likely situation: 100M full-duplex
    // if(link is slow or half) set flags otherwise
    // reg = tmp
    uint32_t maccr = ETH->MACCR | MG_BIT(14) | MG_BIT(13);  // 100M, Full-duplex
    if (speed == MG_PHY_SPEED_10M) maccr &= ~MG_BIT(14);    // 10M
    if (full_duplex == false) maccr &= ~MG_BIT(13);         // Half-duplex
    ETH->MACCR = maccr;  // IRQ handler does not fiddle with this register
    MG_DEBUG(("Link is %uM %s-duplex", maccr & MG_BIT(14) ? 100 : 10,
              maccr & MG_BIT(13) ? "full" : "half"));
  }
  return up;
}

static uint32_t s_rxno;
#if MG_ENABLE_DRIVER_MCXN
void ETHERNET_IRQHandler(void);
void ETHERNET_IRQHandler(void) {
#else
void ETH_IRQHandler(void);
void ETH_IRQHandler(void) {
#endif
  if (ETH->DMACSR & MG_BIT(6)) {           // Frame received, loop
    ETH->DMACSR = MG_BIT(15) | MG_BIT(6);  // Clear flag
    for (uint32_t i = 0; i < 10; i++) {  // read as they arrive but not forever
      if (s_rxdesc[s_rxno][3] & MG_BIT(31)) break;  // exit when done
      if (((s_rxdesc[s_rxno][3] & (MG_BIT(28) | MG_BIT(29))) ==
           (MG_BIT(28) | MG_BIT(29))) &&
          !(s_rxdesc[s_rxno][3] & MG_BIT(15))) {  // skip partial/errored frames
        uint32_t len = s_rxdesc[s_rxno][3] & (MG_BIT(15) - 1);
        // MG_DEBUG(("%lx %lu %lx %08lx", s_rxno, len, s_rxdesc[s_rxno][3],
        // ETH->DMACSR));
        mg_tcpip_qwrite(s_rxbuf[s_rxno], len > 4 ? len - 4 : len, s_ifp);
      }
      s_rxdesc[s_rxno][3] =
          MG_BIT(31) | MG_BIT(30) | MG_BIT(24);  // OWN, IOC, BUF1V
      if (++s_rxno >= ETH_DESC_CNT) s_rxno = 0;
    }
  }
  ETH->DMACSR =
      MG_BIT(7) | MG_BIT(8);  // Clear possible RBU RPS while processing
  ETH->DMACRDTPR =
      (uint32_t) (uintptr_t) &s_rxdesc[ETH_DESC_CNT - 1];  // and resume RX
}

struct mg_tcpip_driver mg_tcpip_driver_stm32h = {
    mg_tcpip_driver_stm32h_init, mg_tcpip_driver_stm32h_tx, NULL,
    mg_tcpip_driver_stm32h_poll};
#endif

#ifdef MG_ENABLE_LINES
#line 1 "src/drivers/tm4c.c"
#endif


#if MG_ENABLE_TCPIP && defined(MG_ENABLE_DRIVER_TM4C) && MG_ENABLE_DRIVER_TM4C
struct tm4c_emac {
  volatile uint32_t EMACCFG, EMACFRAMEFLTR, EMACHASHTBLH, EMACHASHTBLL,
      EMACMIIADDR, EMACMIIDATA, EMACFLOWCTL, EMACVLANTG, RESERVED0, EMACSTATUS,
      EMACRWUFF, EMACPMTCTLSTAT, RESERVED1[2], EMACRIS, EMACIM, EMACADDR0H,
      EMACADDR0L, EMACADDR1H, EMACADDR1L, EMACADDR2H, EMACADDR2L, EMACADDR3H,
      EMACADDR3L, RESERVED2[31], EMACWDOGTO, RESERVED3[8], EMACMMCCTRL,
      EMACMMCRXRIS, EMACMMCTXRIS, EMACMMCRXIM, EMACMMCTXIM, RESERVED4,
      EMACTXCNTGB, RESERVED5[12], EMACTXCNTSCOL, EMACTXCNTMCOL, RESERVED6[4],
      EMACTXOCTCNTG, RESERVED7[6], EMACRXCNTGB, RESERVED8[4], EMACRXCNTCRCERR,
      EMACRXCNTALGNERR, RESERVED9[10], EMACRXCNTGUNI, RESERVED10[239],
      EMACVLNINCREP, EMACVLANHASH, RESERVED11[93], EMACTIMSTCTRL, EMACSUBSECINC,
      EMACTIMSEC, EMACTIMNANO, EMACTIMSECU, EMACTIMNANOU, EMACTIMADD,
      EMACTARGSEC, EMACTARGNANO, EMACHWORDSEC, EMACTIMSTAT, EMACPPSCTRL,
      RESERVED12[12], EMACPPS0INTVL, EMACPPS0WIDTH, RESERVED13[294],
      EMACDMABUSMOD, EMACTXPOLLD, EMACRXPOLLD, EMACRXDLADDR, EMACTXDLADDR,
      EMACDMARIS, EMACDMAOPMODE, EMACDMAIM, EMACMFBOC, EMACRXINTWDT,
      RESERVED14[8], EMACHOSTXDESC, EMACHOSRXDESC, EMACHOSTXBA, EMACHOSRXBA,
      RESERVED15[218], EMACPP, EMACPC, EMACCC, RESERVED16, EMACEPHYRIS,
      EMACEPHYIM, EMACEPHYIMSC;
};
#undef EMAC
#define EMAC ((struct tm4c_emac *) (uintptr_t) 0x400EC000)

#define ETH_PKT_SIZE 1540  // Max frame size
#define ETH_DESC_CNT 4     // Descriptors count
#define ETH_DS 4           // Descriptor size (words)

static uint32_t s_rxdesc[ETH_DESC_CNT][ETH_DS];      // RX descriptors
static uint32_t s_txdesc[ETH_DESC_CNT][ETH_DS];      // TX descriptors
static uint8_t s_rxbuf[ETH_DESC_CNT][ETH_PKT_SIZE];  // RX ethernet buffers
static uint8_t s_txbuf[ETH_DESC_CNT][ETH_PKT_SIZE];  // TX ethernet buffers
static struct mg_tcpip_if *s_ifp;                    // MIP interface
enum {
  EPHY_ADDR = 0,
  EPHYBMCR = 0,
  EPHYBMSR = 1,
  EPHYSTS = 16
};  // PHY constants

static inline void tm4cspin(volatile uint32_t count) {
  while (count--) (void) 0;
}

static uint32_t emac_read_phy(uint8_t addr, uint8_t reg) {
  EMAC->EMACMIIADDR &= (0xf << 2);
  EMAC->EMACMIIADDR |= ((uint32_t) addr << 11) | ((uint32_t) reg << 6);
  EMAC->EMACMIIADDR |= MG_BIT(0);
  while (EMAC->EMACMIIADDR & MG_BIT(0)) tm4cspin(1);
  return EMAC->EMACMIIDATA;
}

static void emac_write_phy(uint8_t addr, uint8_t reg, uint32_t val) {
  EMAC->EMACMIIDATA = val;
  EMAC->EMACMIIADDR &= (0xf << 2);
  EMAC->EMACMIIADDR |= ((uint32_t) addr << 11) | ((uint32_t) reg << 6) | MG_BIT(1);
  EMAC->EMACMIIADDR |= MG_BIT(0);
  while (EMAC->EMACMIIADDR & MG_BIT(0)) tm4cspin(1);
}

static uint32_t get_sysclk(void) {
  struct sysctl {
    volatile uint32_t DONTCARE0[44], RSCLKCFG, DONTCARE1[43], PLLFREQ0,
        PLLFREQ1;
  } *sysctl = (struct sysctl *) 0x400FE000;
  uint32_t clk = 0, piosc = 16000000 /* 16 MHz */, mosc = 25000000 /* 25MHz */;
  if (sysctl->RSCLKCFG & (1 << 28)) {  // USEPLL
    uint32_t fin, vco, mdiv, n, q, psysdiv;
    uint32_t pllsrc = (sysctl->RSCLKCFG & (0xf << 24)) >> 24;
    if (pllsrc == 0) {
      clk = piosc;
    } else if (pllsrc == 3) {
      clk = mosc;
    } else {
      MG_ERROR(("Unsupported clock source"));
    }
    q = (sysctl->PLLFREQ1 & (0x1f << 8)) >> 8;
    n = (sysctl->PLLFREQ1 & (0x1f << 0)) >> 0;
    fin = clk / ((q + 1) * (n + 1));
    mdiv = (sysctl->PLLFREQ0 & (0x3ff << 0)) >>
           0;  // mint + (mfrac / 1024); MFRAC not supported
    psysdiv = (sysctl->RSCLKCFG & (0x3f << 0)) >> 0;
    vco = (uint32_t) ((uint64_t) fin * mdiv);
    return vco / (psysdiv + 1);
  }
  uint32_t oscsrc = (sysctl->RSCLKCFG & (0xf << 20)) >> 20;
  if (oscsrc == 0) {
    clk = piosc;
  } else if (oscsrc == 3) {
    clk = mosc;
  } else {
    MG_ERROR(("Unsupported clock source"));
  }
  uint32_t osysdiv = (sysctl->RSCLKCFG & (0xf << 16)) >> 16;
  return clk / (osysdiv + 1);
}

//  Guess CR from SYSCLK. MDC clock is generated from SYSCLK (AHB); as per
//  802.3, it must not exceed 2.5MHz (also 20.4.2.6) As the AHB clock can be
//  derived from the PIOSC (internal RC), and it can go above  specs, the
//  datasheets specify a range of frequencies and activate one of a series of
//  dividers to keep the MDC clock safely below 2.5MHz. We guess a divider
//  setting based on SYSCLK with a +5% drift. If the user uses a different clock
//  from our defaults, needs to set the macros on top Valid for TM4C129x (20.7)
//  (4.5% worst case drift)
// The PHY receives the main oscillator (MOSC) (20.3.1)
static int guess_mdc_cr(void) {
  uint8_t crs[] = {2, 3, 0, 1};      // EMAC->MACMIIAR::CR values
  uint8_t div[] = {16, 26, 42, 62};  // Respective HCLK dividers
  uint32_t sysclk = get_sysclk();    // Guess system SYSCLK
  int result = -1;                   // Invalid CR value
  if (sysclk < 25000000) {
    MG_ERROR(("SYSCLK too low"));
  } else {
    for (int i = 0; i < 4; i++) {
      if (sysclk / div[i] <= 2375000UL /* 2.5MHz - 5% */) {
        result = crs[i];
        break;
      }
    }
    if (result < 0) MG_ERROR(("SYSCLK too high"));
  }
  MG_DEBUG(("SYSCLK: %u, CR: %d", sysclk, result));
  return result;
}

static bool mg_tcpip_driver_tm4c_init(struct mg_tcpip_if *ifp) {
  struct mg_tcpip_driver_tm4c_data *d =
      (struct mg_tcpip_driver_tm4c_data *) ifp->driver_data;
  s_ifp = ifp;

  // Init RX descriptors
  for (int i = 0; i < ETH_DESC_CNT; i++) {
    s_rxdesc[i][0] = MG_BIT(31);                            // Own
    s_rxdesc[i][1] = sizeof(s_rxbuf[i]) | MG_BIT(14);       // 2nd address chained
    s_rxdesc[i][2] = (uint32_t) (uintptr_t) s_rxbuf[i];  // Point to data buffer
    s_rxdesc[i][3] =
        (uint32_t) (uintptr_t) s_rxdesc[(i + 1) % ETH_DESC_CNT];  // Chain
    // MG_DEBUG(("%d %p", i, s_rxdesc[i]));
  }

  // Init TX descriptors
  for (int i = 0; i < ETH_DESC_CNT; i++) {
    s_txdesc[i][2] = (uint32_t) (uintptr_t) s_txbuf[i];  // Buf pointer
    s_txdesc[i][3] =
        (uint32_t) (uintptr_t) s_txdesc[(i + 1) % ETH_DESC_CNT];  // Chain
  }

  EMAC->EMACDMABUSMOD |= MG_BIT(0);                            // Software reset
  while ((EMAC->EMACDMABUSMOD & MG_BIT(0)) != 0) tm4cspin(1);  // Wait until done

  // Set MDC clock divider. If user told us the value, use it. Otherwise, guess
  int cr = (d == NULL || d->mdc_cr < 0) ? guess_mdc_cr() : d->mdc_cr;
  EMAC->EMACMIIADDR = ((uint32_t) cr & 0xf) << 2;

  // NOTE(cpq): we do not use extended descriptor bit 7, and do not use
  // hardware checksum. Therefore, descriptor size is 4, not 8
  // EMAC->EMACDMABUSMOD = MG_BIT(13) | MG_BIT(16) | MG_BIT(22) | MG_BIT(23) | MG_BIT(25);
  EMAC->EMACIM = MG_BIT(3) | MG_BIT(9);  // Mask timestamp & PMT IT
  EMAC->EMACFLOWCTL = MG_BIT(7);      // Disable zero-quanta pause
  // EMAC->EMACFRAMEFLTR = MG_BIT(31);   // Receive all
  // EMAC->EMACPC defaults to internal PHY (EPHY) in MMI mode
  emac_write_phy(EPHY_ADDR, EPHYBMCR, MG_BIT(15));  // Reset internal PHY (EPHY)
  emac_write_phy(EPHY_ADDR, EPHYBMCR, MG_BIT(12));  // Set autonegotiation
  EMAC->EMACRXDLADDR = (uint32_t) (uintptr_t) s_rxdesc;  // RX descriptors
  EMAC->EMACTXDLADDR = (uint32_t) (uintptr_t) s_txdesc;  // TX descriptors
  EMAC->EMACDMAIM = MG_BIT(6) | MG_BIT(16);                    // RIE, NIE
  EMAC->EMACCFG = MG_BIT(2) | MG_BIT(3) | MG_BIT(11) | MG_BIT(14);   // RE, TE, Duplex, Fast
  EMAC->EMACDMAOPMODE =
      MG_BIT(1) | MG_BIT(13) | MG_BIT(21) | MG_BIT(25);  // SR, ST, TSF, RSF
  EMAC->EMACADDR0H = ((uint32_t) ifp->mac[5] << 8U) | ifp->mac[4];
  EMAC->EMACADDR0L = (uint32_t) (ifp->mac[3] << 24) |
                     ((uint32_t) ifp->mac[2] << 16) |
                     ((uint32_t) ifp->mac[1] << 8) | ifp->mac[0];
  // NOTE(scaprile) There are 3 additional slots for filtering, disabled by
  // default. This also applies to the STM32 driver (at least for F7)
  return true;
}

static uint32_t s_txno;
static size_t mg_tcpip_driver_tm4c_tx(const void *buf, size_t len,
                                      struct mg_tcpip_if *ifp) {
  if (len > sizeof(s_txbuf[s_txno])) {
    MG_ERROR(("Frame too big, %ld", (long) len));
    len = 0;  // fail
  } else if ((s_txdesc[s_txno][0] & MG_BIT(31))) {
    ifp->nerr++;
    MG_ERROR(("No descriptors available"));
    // printf("D0 %lx SR %lx\n", (long) s_txdesc[0][0], (long)
    // EMAC->EMACDMARIS);
    len = 0;  // fail
  } else {
    memcpy(s_txbuf[s_txno], buf, len);     // Copy data
    s_txdesc[s_txno][1] = (uint32_t) len;  // Set data len
    s_txdesc[s_txno][0] =
        MG_BIT(20) | MG_BIT(28) | MG_BIT(29) | MG_BIT(30);  // Chain,FS,LS,IC
    s_txdesc[s_txno][0] |= MG_BIT(31);  // Set OWN bit - let DMA take over
    if (++s_txno >= ETH_DESC_CNT) s_txno = 0;
  }
  EMAC->EMACDMARIS = MG_BIT(2) | MG_BIT(5);  // Clear any prior TU/UNF
  EMAC->EMACTXPOLLD = 0;               // and resume
  return len;
  (void) ifp;
}

static bool mg_tcpip_driver_tm4c_poll(struct mg_tcpip_if *ifp, bool s1) {
  if (!s1) return false;
  uint32_t bmsr = emac_read_phy(EPHY_ADDR, EPHYBMSR);
  bool up = (bmsr & MG_BIT(2)) ? 1 : 0;
  if ((ifp->state == MG_TCPIP_STATE_DOWN) && up) {  // link state just went up
    uint32_t sts = emac_read_phy(EPHY_ADDR, EPHYSTS);
    // tmp = reg with flags set to the most likely situation: 100M full-duplex
    // if(link is slow or half) set flags otherwise
    // reg = tmp
    uint32_t emaccfg = EMAC->EMACCFG | MG_BIT(14) | MG_BIT(11);  // 100M, Full-duplex
    if (sts & MG_BIT(1)) emaccfg &= ~MG_BIT(14);                 // 10M
    if ((sts & MG_BIT(2)) == 0) emaccfg &= ~MG_BIT(11);          // Half-duplex
    EMAC->EMACCFG = emaccfg;  // IRQ handler does not fiddle with this register
    MG_DEBUG(("Link is %uM %s-duplex", emaccfg & MG_BIT(14) ? 100 : 10,
              emaccfg & MG_BIT(11) ? "full" : "half"));
  }
  return up;
}

void EMAC0_IRQHandler(void);
static uint32_t s_rxno;
void EMAC0_IRQHandler(void) {
  if (EMAC->EMACDMARIS & MG_BIT(6)) {        // Frame received, loop
    EMAC->EMACDMARIS = MG_BIT(16) | MG_BIT(6);  // Clear flag
    for (uint32_t i = 0; i < 10; i++) {   // read as they arrive but not forever
      if (s_rxdesc[s_rxno][0] & MG_BIT(31)) break;  // exit when done
      if (((s_rxdesc[s_rxno][0] & (MG_BIT(8) | MG_BIT(9))) == (MG_BIT(8) | MG_BIT(9))) &&
          !(s_rxdesc[s_rxno][0] & MG_BIT(15))) {  // skip partial/errored frames
        uint32_t len = ((s_rxdesc[s_rxno][0] >> 16) & (MG_BIT(14) - 1));
        //  printf("%lx %lu %lx %.8lx\n", s_rxno, len, s_rxdesc[s_rxno][0],
        //  EMAC->EMACDMARIS);
        mg_tcpip_qwrite(s_rxbuf[s_rxno], len > 4 ? len - 4 : len, s_ifp);
      }
      s_rxdesc[s_rxno][0] = MG_BIT(31);
      if (++s_rxno >= ETH_DESC_CNT) s_rxno = 0;
    }
  }
  EMAC->EMACDMARIS = MG_BIT(7);  // Clear possible RU while processing
  EMAC->EMACRXPOLLD = 0;      // and resume RX
}

struct mg_tcpip_driver mg_tcpip_driver_tm4c = {mg_tcpip_driver_tm4c_init,
                                               mg_tcpip_driver_tm4c_tx, NULL,
                                               mg_tcpip_driver_tm4c_poll};
#endif

#ifdef MG_ENABLE_LINES
#line 1 "src/drivers/tms570.c"
#endif


#if MG_ENABLE_TCPIP && defined(MG_ENABLE_DRIVER_TMS570) && MG_ENABLE_DRIVER_TMS570
struct tms570_emac_ctrl {
  volatile uint32_t REVID, SOFTRESET, RESERVED1[1], INTCONTROL, C0RXTHRESHEN,
  C0RXEN, C0TXEN, C0MISCEN, RESERVED2[8],
  C0RXTHRESHSTAT, C0RXSTAT, C0TXSTAT, C0MISCSTAT,
  RESERVED3[8],
  C0RXIMAX, C0TXIMAX;
};
struct tms570_emac {
  volatile uint32_t TXREVID, TXCONTROL, TXTEARDOWN, RESERVED1[1], RXREVID,
  RXCONTROL, RXTEARDOWN, RESERVED2[25], TXINTSTATRAW,TXINTSTATMASKED,
  TXINTMASKSET, TXINTMASKCLEAR, MACINVECTOR, MACEOIVECTOR, RESERVED8[2], RXINTSTATRAW,
  RXINTSTATMASKED, RXINTMASKSET, RXINTMASKCLEAR, MACINTSTATRAW, MACINTSTATMASKED,
  MACINTMASKSET, MACINTMASKCLEAR, RESERVED3[16], RXMBPENABLE, RXUNICASTSET,
  RXUNICASTCLEAR, RXMAXLEN, RXBUFFEROFFSET, RXFILTERLOWTHRESH, RESERVED9[2], RXFLOWTHRESH[8],
  RXFREEBUFFER[8], MACCONTROL, MACSTATUS, EMCONTROL, FIFOCONTROL, MACCONFIG,
  SOFTRESET, RESERVED4[22], MACSRCADDRLO, MACSRCADDRHI, MACHASH1, MACHASH2,
  BOFFTEST, TPACETEST, RXPAUSE, TXPAUSE, RESERVED5[4], RXGOODFRAMES, RXBCASTFRAMES,
  RXMCASTFRAMES, RXPAUSEFRAMES, RXCRCERRORS, RXALIGNCODEERRORS, RXOVERSIZED,
  RXJABBER, RXUNDERSIZED, RXFRAGMENTS, RXFILTERED, RXQOSFILTERED, RXOCTETS,
  TXGOODFRAMES, TXBCASTFRAMES, TXMCASTFRAMES, TXPAUSEFRAMES, TXDEFERRED,
  TXCOLLISION, TXSINGLECOLL, TXMULTICOLL, TXEXCESSIVECOLL, TXLATECOLL,
  TXUNDERRUN, TXCARRIERSENSE, TXOCTETS, FRAME64, FRAME65T127, FRAME128T255,
  FRAME256T511, FRAME512T1023, FRAME1024TUP, NETOCTETS, RXSOFOVERRUNS,
  RXMOFOVERRUNS, RXDMAOVERRUNS, RESERVED6[156], MACADDRLO, MACADDRHI,
  MACINDEX, RESERVED7[61], TXHDP[8], RXHDP[8], TXCP[8], RXCP[8];
};
struct tms570_mdio {
  volatile uint32_t REVID, CONTROL, ALIVE, LINK, LINKINTRAW, LINKINTMASKED,
  RESERVED1[2], USERINTRAW, USERINTMASKED, USERINTMASKSET, USERINTMASKCLEAR,
  RESERVED2[20], USERACCESS0, USERPHYSEL0, USERACCESS1, USERPHYSEL1;
};
#define SWAP32(x) ( (((x) & 0x000000FF) << 24) | \
                              (((x) & 0x0000FF00) << 8)  | \
                              (((x) & 0x00FF0000) >> 8)  | \
                              (((x) & 0xFF000000) >> 24) )
#undef EMAC
#undef EMAC_CTRL
#undef MDIO
#define EMAC ((struct tms570_emac *) (uintptr_t) 0xFCF78000)
#define EMAC_CTRL ((struct tms570_emac_ctrl *) (uintptr_t) 0xFCF78800)
#define MDIO ((struct tms570_mdio *) (uintptr_t) 0xFCF78900)
#define ETH_PKT_SIZE 1540  // Max frame size
#define ETH_DESC_CNT 4     // Descriptors count
#define ETH_DS 4           // Descriptor size (words)
static uint32_t s_txdesc[ETH_DESC_CNT][ETH_DS] 
  __attribute__((section(".ETH_CPPI"), aligned(4)));      // TX descriptors
static uint32_t s_rxdesc[ETH_DESC_CNT][ETH_DS] 
  __attribute__((section(".ETH_CPPI"), aligned(4)));      // RX descriptors
static uint8_t s_rxbuf[ETH_DESC_CNT][ETH_PKT_SIZE] 
  __attribute__((aligned(4)));  // RX ethernet buffers
static uint8_t s_txbuf[ETH_DESC_CNT][ETH_PKT_SIZE] 
  __attribute__((aligned(4)));  // TX ethernet buffers
static struct mg_tcpip_if *s_ifp;                    // MIP interface
static uint16_t emac_read_phy(uint8_t addr, uint8_t reg) {
  while(MDIO->USERACCESS0 & MG_BIT(31)) (void) 0;
  MDIO->USERACCESS0 = MG_BIT(31) | ((reg & 0x1f) << 21) |
                      ((addr & 0x1f) << 16);
  while(MDIO->USERACCESS0 & MG_BIT(31)) (void) 0;
  return MDIO->USERACCESS0 & 0xffff;
}
static void emac_write_phy(uint8_t addr, uint8_t reg, uint16_t val) {
  while(MDIO->USERACCESS0 & MG_BIT(31)) (void) 0;
  MDIO->USERACCESS0 = MG_BIT(31) | MG_BIT(30) | ((reg & 0x1f) << 21) |
                      ((addr & 0x1f) << 16) | (val & 0xffff);
  while(MDIO->USERACCESS0 & MG_BIT(31)) (void) 0;
}
static bool mg_tcpip_driver_tms570_init(struct mg_tcpip_if *ifp) {
  struct mg_tcpip_driver_tms570_data *d =
      (struct mg_tcpip_driver_tms570_data *) ifp->driver_data;
  s_ifp = ifp;
  EMAC_CTRL->SOFTRESET = MG_BIT(0); // Reset the EMAC Control Module
  while(EMAC_CTRL->SOFTRESET & MG_BIT(0)) (void) 0; // wait
  EMAC->SOFTRESET = MG_BIT(0); // Reset the EMAC Module
  while(EMAC->SOFTRESET & MG_BIT(0)) (void) 0;
  EMAC->MACCONTROL = 0;
  EMAC->RXCONTROL = 0;
  EMAC->TXCONTROL = 0;
  // Initialize all the header descriptor pointer registers
  uint32_t i;
  for(i =  0; i < ETH_DESC_CNT; i++) {
    EMAC->RXHDP[i] = 0;
    EMAC->TXHDP[i] = 0;
    EMAC->RXCP[i] = 0;
    EMAC->TXCP[i] = 0;
    ///EMAC->RXFREEBUFFER[i] = 0xff;
  }
  // Clear the interrupt enable for all the channels
  EMAC->TXINTMASKCLEAR = 0xff;
  EMAC->RXINTMASKCLEAR = 0xff;
  EMAC->MACHASH1 = 0;
  EMAC->MACHASH2 = 0;
  EMAC->RXBUFFEROFFSET = 0;
  EMAC->RXUNICASTCLEAR = 0xff;
  EMAC->RXUNICASTSET = 0;
  EMAC->RXMBPENABLE = 0;
  // init MDIO
  // MDIO_CLK frequency = VCLK3/(CLKDIV + 1). (MDIO must be between 1.0 - 2.5Mhz)
  uint32_t clkdiv = 75; // VCLK is configured to 75Mhz
  // CLKDIV, ENABLE, PREAMBLE, FAULTENB
  MDIO->CONTROL = (clkdiv - 1) | MG_BIT(30) | MG_BIT(20) | MG_BIT(18);
  volatile int delay = 0xfff;
  while (delay-- != 0) (void) 0;
  struct mg_phy phy = {emac_read_phy, emac_write_phy};
  mg_phy_init(&phy, d->phy_addr, MG_PHY_CLOCKS_MAC);
  // set the mac address
  EMAC->MACSRCADDRHI = ifp->mac[0] | (ifp->mac[1] << 8) | (ifp->mac[2] << 16) |
                       (ifp->mac[3] << 24);
  EMAC->MACSRCADDRLO = ifp->mac[4] | (ifp->mac[5] << 8);
  uint32_t channel;
  for (channel = 0; channel < 8; channel++) {
    EMAC->MACINDEX = channel;
    EMAC->MACADDRHI = ifp->mac[0] | (ifp->mac[1] << 8) | (ifp->mac[2] << 16) |
                       (ifp->mac[3] << 24);
    EMAC->MACADDRLO = ifp->mac[4] | (ifp->mac[5] << 8) | MG_BIT(20) |
                      MG_BIT(19) | (channel << 16);
  }
  EMAC->RXUNICASTSET = 1; // accept unicast frames;
  EMAC->RXMBPENABLE = MG_BIT(30) | MG_BIT(13); // CRC, broadcast;
  
  // Initialize the descriptors
  for (i = 0; i < ETH_DESC_CNT; i++) {
    if (i < ETH_DESC_CNT - 1) {
      s_txdesc[i][0] = 0;
      s_rxdesc[i][0] = SWAP32(((uint32_t) &s_rxdesc[i + 1][0]));
    }
    s_txdesc[i][1] = SWAP32(((uint32_t) s_txbuf[i]));
    s_rxdesc[i][1] = SWAP32(((uint32_t) s_rxbuf[i]));
    s_txdesc[i][2] = 0;
    s_rxdesc[i][2] = SWAP32(ETH_PKT_SIZE);
    s_txdesc[i][3] = 0;
    s_rxdesc[i][3] = SWAP32(MG_BIT(29)); // OWN
  }
  s_txdesc[ETH_DESC_CNT - 1][0] = 0;
  s_rxdesc[ETH_DESC_CNT - 1][0] = 0;
  
  EMAC->MACCONTROL = MG_BIT(5) | MG_BIT(0); // Enable MII, Full-duplex
  //EMAC->TXINTMASKSET = 1; // Enable TX interrupt
  EMAC->RXINTMASKSET = 1; // Enable RX interrupt
  //EMAC_CTRL->C0TXEN = 1; // TX completion interrupt
  EMAC_CTRL->C0RXEN = 1; // RX completion interrupt
  EMAC->TXCONTROL = 1; // TXEN
  EMAC->RXCONTROL = 1; // RXEN
  EMAC->RXHDP[0] = (uint32_t) &s_rxdesc[0][0];
  return true;
}
static uint32_t s_txno;
static size_t mg_tcpip_driver_tms570_tx(const void *buf, size_t len,
                                      struct mg_tcpip_if *ifp) {
  if (len > sizeof(s_txbuf[s_txno])) {
    MG_ERROR(("Frame too big, %ld", (long) len));
    len = 0;  // fail
  } else if ((s_txdesc[s_txno][3] & SWAP32(MG_BIT(29)))) {
    ifp->nerr++;
    MG_ERROR(("No descriptors available"));
    len = 0;  // fail
  } else {
    memcpy(s_txbuf[s_txno], buf, len);     // Copy data
    if (len < 128) len = 128;
    s_txdesc[s_txno][2] = SWAP32((uint32_t) len);  // Set data len
    s_txdesc[s_txno][3] =
        SWAP32(MG_BIT(31) | MG_BIT(30) | MG_BIT(29) | len);  // SOP, EOP, OWN, length
    
    while(EMAC->TXHDP[0] != 0) (void) 0;
    EMAC->TXHDP[0] = (uint32_t) &s_txdesc[s_txno][0];
    if(++s_txno == ETH_DESC_CNT) {
      s_txno = 0;
    }
  }
  return len;
  (void) ifp;
}
static bool mg_tcpip_driver_tms570_poll(struct mg_tcpip_if *ifp, bool s1) {
  struct mg_tcpip_driver_tms570_data *d =
      (struct mg_tcpip_driver_tms570_data *) ifp->driver_data;
  uint8_t speed = MG_PHY_SPEED_10M;
  bool up = false, full_duplex = false;
  struct mg_phy phy = {emac_read_phy, emac_write_phy};
  if (!s1) return false;
  up = mg_phy_up(&phy, d->phy_addr, &full_duplex, &speed);
  if ((ifp->state == MG_TCPIP_STATE_DOWN) && up) {
    // link state just went up
    MG_DEBUG(("Link is %uM %s-duplex", speed == MG_PHY_SPEED_10M ? 10 : 100,
              full_duplex ? "full" : "half"));
  }
  return up;
}
#pragma CODE_STATE(EMAC_TX_IRQHandler, 32)
#pragma INTERRUPT(EMAC_TX_IRQHandler, IRQ)
void EMAC_TX_IRQHandler(void) {
  uint32_t status = EMAC_CTRL->C0TXSTAT;
  if (status & 1) { // interrupt caused on channel 0
    while(s_txdesc[s_txno][3] & SWAP32(MG_BIT(29))) (void) 0;
    EMAC->TXCP[0] = (uint32_t) &s_txdesc[s_txno][0];
  }
  //Write the DMA end of interrupt vector
  EMAC->MACEOIVECTOR = 2;
}
static uint32_t s_rxno;
#pragma CODE_STATE(EMAC_RX_IRQHandler, 32)
#pragma INTERRUPT(EMAC_RX_IRQHandler, IRQ)
void EMAC_RX_IRQHandler(void) {
  uint32_t status = EMAC_CTRL->C0RXSTAT;
  if (status & 1) { // Frame received, loop
    uint32_t i;
    //MG_INFO(("RX interrupt"));
    for (i = 0; i < 10; i++) {   // read as they arrive but not forever
      if (s_rxdesc[s_rxno][3] & SWAP32(MG_BIT(29))) break;
      uint32_t len = SWAP32(s_rxdesc[s_rxno][3]) & 0xffff;
      //MG_INFO(("recv len: %d", len));
      //mg_hexdump(s_rxbuf[s_rxno], len);
      mg_tcpip_qwrite(s_rxbuf[s_rxno], len > 4 ? len - 4 : len, s_ifp);
      uint32_t flags = s_rxdesc[s_rxno][3];
      s_rxdesc[s_rxno][3] = SWAP32(MG_BIT(29));
      s_rxdesc[s_rxno][2] = SWAP32(ETH_PKT_SIZE);
      EMAC->RXCP[0] = (uint32_t) &s_rxdesc[s_rxno][0];
      if (flags & SWAP32(MG_BIT(28))) {
        //MG_INFO(("EOQ detected"));
        EMAC->RXHDP[0] = (uint32_t) &s_rxdesc[0][0];
      }
      if (++s_rxno >= ETH_DESC_CNT) s_rxno = 0;
    }
  }
  //Write the DMA end of interrupt vector
  EMAC->MACEOIVECTOR = 1;
}
struct mg_tcpip_driver mg_tcpip_driver_tms570 = {mg_tcpip_driver_tms570_init,
                                               mg_tcpip_driver_tms570_tx, NULL,
                                               mg_tcpip_driver_tms570_poll};
#endif


#ifdef MG_ENABLE_LINES
#line 1 "src/drivers/w5100.c"
#endif


#if MG_ENABLE_TCPIP && defined(MG_ENABLE_DRIVER_W5100) && MG_ENABLE_DRIVER_W5100

static void w5100_txn(struct mg_tcpip_spi *s, uint16_t addr, bool wr, void *buf,
                      size_t len) {
  size_t i;
  uint8_t *p = (uint8_t *) buf;
  uint8_t control = wr ? 0xF0 : 0x0F;
  uint8_t cmd[] = {control, (uint8_t) (addr >> 8), (uint8_t) (addr & 255)};
  s->begin(s->spi);
  for (i = 0; i < sizeof(cmd); i++) s->txn(s->spi, cmd[i]);
  for (i = 0; i < len; i++) {
    uint8_t r = s->txn(s->spi, p[i]);
    if (!wr) p[i] = r;
  }
  s->end(s->spi);
}

// clang-format off
static  void w5100_wn(struct mg_tcpip_spi *s, uint16_t addr, void *buf, size_t len) { w5100_txn(s, addr, true, buf, len); }
static  void w5100_w1(struct mg_tcpip_spi *s, uint16_t addr, uint8_t val) { w5100_wn(s, addr, &val, 1); }
static  void w5100_w2(struct mg_tcpip_spi *s, uint16_t addr, uint16_t val) { uint8_t buf[2] = {(uint8_t) (val >> 8), (uint8_t) (val & 255)}; w5100_wn(s, addr, buf, sizeof(buf)); }
static  void w5100_rn(struct mg_tcpip_spi *s, uint16_t addr, void *buf, size_t len) { w5100_txn(s, addr, false, buf, len); }
static  uint8_t w5100_r1(struct mg_tcpip_spi *s, uint16_t addr) { uint8_t r = 0; w5100_rn(s, addr, &r, 1); return r; }
static  uint16_t w5100_r2(struct mg_tcpip_spi *s, uint16_t addr) { uint8_t buf[2] = {0, 0}; w5100_rn(s, addr, buf, sizeof(buf)); return (uint16_t) ((buf[0] << 8) | buf[1]); }
// clang-format on

static size_t w5100_rx(void *buf, size_t buflen, struct mg_tcpip_if *ifp) {
  struct mg_tcpip_spi *s = (struct mg_tcpip_spi *) ifp->driver_data;
  uint16_t r = 0, n = 0, len = (uint16_t) buflen, n2;  // Read recv len
  while ((n2 = w5100_r2(s, 0x426)) > n) n = n2;        // Until it is stable
  if (n > 0) {
    uint16_t ptr = w5100_r2(s, 0x428);  // Get read pointer
    if (n <= len + 2 && n > 1) {
      r = (uint16_t) (n - 2);
    }
    uint16_t rxbuf_size = (1 << (w5100_r1(s, 0x1a) & 3)) * 1024;
    uint16_t rxbuf_addr = 0x6000;
    uint16_t ptr_ofs = (ptr + 2) & (rxbuf_size - 1);
    if (ptr_ofs + r < rxbuf_size) {
      w5100_rn(s, rxbuf_addr + ptr_ofs, buf, r);
    } else {
      uint16_t remaining_len = rxbuf_size - ptr_ofs;
      w5100_rn(s, rxbuf_addr + ptr_ofs, buf, remaining_len);
      w5100_rn(s, rxbuf_addr, buf + remaining_len, n - remaining_len);
    }
    w5100_w2(s, 0x428, (uint16_t) (ptr + n));
    w5100_w1(s, 0x401, 0x40);  // Sock0 CR -> RECV
  }
  return r;
}

static size_t w5100_tx(const void *buf, size_t buflen,
                       struct mg_tcpip_if *ifp) {
  struct mg_tcpip_spi *s = (struct mg_tcpip_spi *) ifp->driver_data;
  uint16_t i, n = 0, ptr = 0, len = (uint16_t) buflen;
  while (n < len) n = w5100_r2(s, 0x420);  // Wait for space
  ptr = w5100_r2(s, 0x424);                // Get write pointer
  uint16_t txbuf_size = (1 << (w5100_r1(s, 0x1b) & 3)) * 1024;
  uint16_t ptr_ofs = ptr & (txbuf_size - 1);
  uint16_t txbuf_addr = 0x4000;
  if (ptr_ofs + len > txbuf_size) {
    uint16_t size = txbuf_size - ptr_ofs;
    w5100_wn(s, txbuf_addr + ptr_ofs, (char *) buf, size);
    w5100_wn(s, txbuf_addr, (char *) buf + size, len - size);
  } else {
    w5100_wn(s, txbuf_addr + ptr_ofs, (char *) buf, len);
  }
  w5100_w2(s, 0x424, (uint16_t) (ptr + len));  // Advance write pointer
  w5100_w1(s, 0x401, 0x20);                    // Sock0 CR -> SEND
  for (i = 0; i < 40; i++) {
    uint8_t ir = w5100_r1(s, 0x402);  // Read S0 IR
    if (ir == 0) continue;
    // printf("IR %d, len=%d, free=%d, ptr %d\n", ir, (int) len, (int) n, ptr);
    w5100_w1(s, 0x402, ir);    // Write S0 IR: clear it!
    if (ir & 8) len = 0;       // Timeout. Report error
    if (ir & (16 | 8)) break;  // Stop on SEND_OK or timeout
  }
  return len;
}

static bool w5100_init(struct mg_tcpip_if *ifp) {
  struct mg_tcpip_spi *s = (struct mg_tcpip_spi *) ifp->driver_data;
  s->end(s->spi);
  w5100_w1(s, 0, 0x80);               // Reset chip: CR -> 0x80
  w5100_w1(s, 0x72, 0x53);            // CR PHYLCKR -> unlock PHY
  w5100_w1(s, 0x46, 0);               // CR PHYCR0 -> autonegotiation
  w5100_w1(s, 0x47, 0);               // CR PHYCR1 -> reset
  w5100_w1(s, 0x72, 0x00);            // CR PHYLCKR -> lock PHY
  w5100_w1(s, 0x1a, 6);               // Sock0 RX buf size - 4KB
  w5100_w1(s, 0x1b, 6);               // Sock0 TX buf size - 4KB
  w5100_w1(s, 0x400, 4);              // Sock0 MR -> MACRAW
  w5100_w1(s, 0x401, 1);              // Sock0 CR -> OPEN
  return w5100_r1(s, 0x403) == 0x42;  // Sock0 SR == MACRAW
}

static bool w5100_poll(struct mg_tcpip_if *ifp, bool s1) {
  struct mg_tcpip_spi *spi = (struct mg_tcpip_spi *) ifp->driver_data;
  return s1 ? w5100_r1(spi, 0x3c /* PHYSR */) & 1
            : false;  // Bit 0 of PHYSR is LNK (0 - down, 1 - up)
}

struct mg_tcpip_driver mg_tcpip_driver_w5100 = {w5100_init, w5100_tx, w5100_rx,
                                                w5100_poll};
#endif

#ifdef MG_ENABLE_LINES
#line 1 "src/drivers/w5500.c"
#endif


#if MG_ENABLE_TCPIP && defined(MG_ENABLE_DRIVER_W5500) && MG_ENABLE_DRIVER_W5500

enum { W5500_CR = 0, W5500_S0 = 1, W5500_TX0 = 2, W5500_RX0 = 3 };

static void w5500_txn(struct mg_tcpip_spi *s, uint8_t block, uint16_t addr,
                      bool wr, void *buf, size_t len) {
  size_t i;
  uint8_t *p = (uint8_t *) buf;
  uint8_t cmd[] = {(uint8_t) (addr >> 8), (uint8_t) (addr & 255),
                   (uint8_t) ((block << 3) | (wr ? 4 : 0))};
  s->begin(s->spi);
  for (i = 0; i < sizeof(cmd); i++) s->txn(s->spi, cmd[i]);
  for (i = 0; i < len; i++) {
    uint8_t r = s->txn(s->spi, p[i]);
    if (!wr) p[i] = r;
  }
  s->end(s->spi);
}

// clang-format off
static  void w5500_wn(struct mg_tcpip_spi *s, uint8_t block, uint16_t addr, void *buf, size_t len) { w5500_txn(s, block, addr, true, buf, len); }
static  void w5500_w1(struct mg_tcpip_spi *s, uint8_t block, uint16_t addr, uint8_t val) { w5500_wn(s, block, addr, &val, 1); }
static  void w5500_w2(struct mg_tcpip_spi *s, uint8_t block, uint16_t addr, uint16_t val) { uint8_t buf[2] = {(uint8_t) (val >> 8), (uint8_t) (val & 255)}; w5500_wn(s, block, addr, buf, sizeof(buf)); }
static  void w5500_rn(struct mg_tcpip_spi *s, uint8_t block, uint16_t addr, void *buf, size_t len) { w5500_txn(s, block, addr, false, buf, len); }
static  uint8_t w5500_r1(struct mg_tcpip_spi *s, uint8_t block, uint16_t addr) { uint8_t r = 0; w5500_rn(s, block, addr, &r, 1); return r; }
static  uint16_t w5500_r2(struct mg_tcpip_spi *s, uint8_t block, uint16_t addr) { uint8_t buf[2] = {0, 0}; w5500_rn(s, block, addr, buf, sizeof(buf)); return (uint16_t) ((buf[0] << 8) | buf[1]); }
// clang-format on

static size_t w5500_rx(void *buf, size_t buflen, struct mg_tcpip_if *ifp) {
  struct mg_tcpip_spi *s = (struct mg_tcpip_spi *) ifp->driver_data;
  uint16_t r = 0, n = 0, len = (uint16_t) buflen, n2;     // Read recv len
  while ((n2 = w5500_r2(s, W5500_S0, 0x26)) > n) n = n2;  // Until it is stable
  // printf("RSR: %d\n", (int) n);
  if (n > 0) {
    uint16_t ptr = w5500_r2(s, W5500_S0, 0x28);  // Get read pointer
    n = w5500_r2(s, W5500_RX0, ptr);             // Read frame length
    if (n <= len + 2 && n > 1) {
      r = (uint16_t) (n - 2);
      w5500_rn(s, W5500_RX0, (uint16_t) (ptr + 2), buf, r);
    }
    w5500_w2(s, W5500_S0, 0x28, (uint16_t) (ptr + n));  // Advance read pointer
    w5500_w1(s, W5500_S0, 1, 0x40);                     // Sock0 CR -> RECV
    // printf("  RX_RD: tot=%u n=%u r=%u\n", n2, n, r);
  }
  return r;
}

static size_t w5500_tx(const void *buf, size_t buflen,
                       struct mg_tcpip_if *ifp) {
  struct mg_tcpip_spi *s = (struct mg_tcpip_spi *) ifp->driver_data;
  uint16_t i, ptr, n = 0, len = (uint16_t) buflen;
  while (n < len) n = w5500_r2(s, W5500_S0, 0x20);      // Wait for space
  ptr = w5500_r2(s, W5500_S0, 0x24);                    // Get write pointer
  w5500_wn(s, W5500_TX0, ptr, (void *) buf, len);       // Write data
  w5500_w2(s, W5500_S0, 0x24, (uint16_t) (ptr + len));  // Advance write pointer
  w5500_w1(s, W5500_S0, 1, 0x20);                       // Sock0 CR -> SEND
  for (i = 0; i < 40; i++) {
    uint8_t ir = w5500_r1(s, W5500_S0, 2);  // Read S0 IR
    if (ir == 0) continue;
    // printf("IR %d, len=%d, free=%d, ptr %d\n", ir, (int) len, (int) n, ptr);
    w5500_w1(s, W5500_S0, 2, ir);  // Write S0 IR: clear it!
    if (ir & 8) len = 0;           // Timeout. Report error
    if (ir & (16 | 8)) break;      // Stop on SEND_OK or timeout
  }
  return len;
}

static bool w5500_init(struct mg_tcpip_if *ifp) {
  struct mg_tcpip_spi *s = (struct mg_tcpip_spi *) ifp->driver_data;
  s->end(s->spi);
  w5500_w1(s, W5500_CR, 0, 0x80);     // Reset chip: CR -> 0x80
  w5500_w1(s, W5500_CR, 0x2e, 0);     // CR PHYCFGR -> reset
  w5500_w1(s, W5500_CR, 0x2e, 0xf8);  // CR PHYCFGR -> set
  // w5500_wn(s, W5500_CR, 9, s->mac, 6);      // Set source MAC
  w5500_w1(s, W5500_S0, 0x1e, 16);          // Sock0 RX buf size
  w5500_w1(s, W5500_S0, 0x1f, 16);          // Sock0 TX buf size
  w5500_w1(s, W5500_S0, 0, 4);              // Sock0 MR -> MACRAW
  w5500_w1(s, W5500_S0, 1, 1);              // Sock0 CR -> OPEN
  return w5500_r1(s, W5500_S0, 3) == 0x42;  // Sock0 SR == MACRAW
}

static bool w5500_poll(struct mg_tcpip_if *ifp, bool s1) {
  struct mg_tcpip_spi *spi = (struct mg_tcpip_spi *) ifp->driver_data;
  return s1 ? w5500_r1(spi, W5500_CR, 0x2e /* PHYCFGR */) & 1
            : false;  // Bit 0 of PHYCFGR is LNK (0 - down, 1 - up)
}

struct mg_tcpip_driver mg_tcpip_driver_w5500 = {w5500_init, w5500_tx, w5500_rx,
                                                w5500_poll};
#endif

#ifdef MG_ENABLE_LINES
#line 1 "src/drivers/xmc.c"
#endif


#if MG_ENABLE_TCPIP && defined(MG_ENABLE_DRIVER_XMC) && MG_ENABLE_DRIVER_XMC

struct ETH_GLOBAL_TypeDef {
  volatile uint32_t MAC_CONFIGURATION, MAC_FRAME_FILTER, HASH_TABLE_HIGH,
  HASH_TABLE_LOW, GMII_ADDRESS, GMII_DATA, FLOW_CONTROL, VLAN_TAG, VERSION,
  DEBUG, REMOTE_WAKE_UP_FRAME_FILTER, PMT_CONTROL_STATUS, RESERVED[2],
  INTERRUPT_STATUS, INTERRUPT_MASK, MAC_ADDRESS0_HIGH, MAC_ADDRESS0_LOW,
  MAC_ADDRESS1_HIGH, MAC_ADDRESS1_LOW, MAC_ADDRESS2_HIGH, MAC_ADDRESS2_LOW,
  MAC_ADDRESS3_HIGH, MAC_ADDRESS3_LOW, RESERVED1[40], MMC_CONTROL,
  MMC_RECEIVE_INTERRUPT, MMC_TRANSMIT_INTERRUPT, MMC_RECEIVE_INTERRUPT_MASK,
  MMC_TRANSMIT_INTERRUPT_MASK, TX_STATISTICS[26], RESERVED2,
  RX_STATISTICS_1[26], RESERVED3[6], MMC_IPC_RECEIVE_INTERRUPT_MASK,
  RESERVED4, MMC_IPC_RECEIVE_INTERRUPT, RESERVED5, RX_STATISTICS_2[30],
  RESERVED7[286], TIMESTAMP_CONTROL, SUB_SECOND_INCREMENT,
  SYSTEM_TIME_SECONDS, SYSTEM_TIME_NANOSECONDS,
  SYSTEM_TIME_SECONDS_UPDATE, SYSTEM_TIME_NANOSECONDS_UPDATE,
  TIMESTAMP_ADDEND, TARGET_TIME_SECONDS, TARGET_TIME_NANOSECONDS,
  SYSTEM_TIME_HIGHER_WORD_SECONDS, TIMESTAMP_STATUS,
  PPS_CONTROL, RESERVED8[564], BUS_MODE, TRANSMIT_POLL_DEMAND,
  RECEIVE_POLL_DEMAND, RECEIVE_DESCRIPTOR_LIST_ADDRESS,
  TRANSMIT_DESCRIPTOR_LIST_ADDRESS, STATUS, OPERATION_MODE,
  INTERRUPT_ENABLE, MISSED_FRAME_AND_BUFFER_OVERFLOW_COUNTER,
  RECEIVE_INTERRUPT_WATCHDOG_TIMER, RESERVED9, AHB_STATUS,
  RESERVED10[6], CURRENT_HOST_TRANSMIT_DESCRIPTOR,
  CURRENT_HOST_RECEIVE_DESCRIPTOR, CURRENT_HOST_TRANSMIT_BUFFER_ADDRESS,
  CURRENT_HOST_RECEIVE_BUFFER_ADDRESS, HW_FEATURE;
};

#undef ETH0
#define ETH0  ((struct ETH_GLOBAL_TypeDef*) 0x5000C000UL)

#define ETH_PKT_SIZE 1536 // Max frame size
#define ETH_DESC_CNT 4     // Descriptors count
#define ETH_DS 4           // Descriptor size (words)

#ifndef ETH_RAM_SECTION
// if no section is specified, then the data will be placed in the default
// bss section
#define ETH_RAM_SECTION
#endif

static uint8_t s_rxbuf[ETH_DESC_CNT][ETH_PKT_SIZE] ETH_RAM_SECTION;
static uint8_t s_txbuf[ETH_DESC_CNT][ETH_PKT_SIZE] ETH_RAM_SECTION;
static uint32_t s_rxdesc[ETH_DESC_CNT][ETH_DS] ETH_RAM_SECTION;  // RX descriptors
static uint32_t s_txdesc[ETH_DESC_CNT][ETH_DS] ETH_RAM_SECTION;  // TX descriptors
static uint8_t s_txno;                           // Current TX descriptor
static uint8_t s_rxno;                           // Current RX descriptor

static struct mg_tcpip_if *s_ifp;  // MIP interface
enum { MG_PHY_ADDR = 0, MG_PHYREG_BCR = 0, MG_PHYREG_BSR = 1 };

static uint16_t eth_read_phy(uint8_t addr, uint8_t reg) {
  ETH0->GMII_ADDRESS = (ETH0->GMII_ADDRESS & 0x3c) |
                        ((uint32_t)addr << 11) |
                        ((uint32_t)reg << 6) | 1;
  while ((ETH0->GMII_ADDRESS & 1) != 0) (void) 0;
  return (uint16_t)(ETH0->GMII_DATA & 0xffff);
}

static void eth_write_phy(uint8_t addr, uint8_t reg, uint16_t val) {
  ETH0->GMII_DATA  = val;
  ETH0->GMII_ADDRESS = (ETH0->GMII_ADDRESS & 0x3c) |
                        ((uint32_t)addr << 11) |
                        ((uint32_t)reg << 6) | 3;
  while ((ETH0->GMII_ADDRESS & 1) != 0) (void) 0;
}

static uint32_t get_clock_rate(struct mg_tcpip_driver_xmc_data *d) {
  if (d->mdc_cr == -1) {
    // assume ETH clock is 60MHz by default
    // then according to 13.2.8.1, we need to set value 3
    return 3;
  }

  return d->mdc_cr;
}

static bool mg_tcpip_driver_xmc_init(struct mg_tcpip_if *ifp) {
  struct mg_tcpip_driver_xmc_data *d =
      (struct mg_tcpip_driver_xmc_data *) ifp->driver_data;
  s_ifp = ifp;

  // reset MAC
  ETH0->BUS_MODE |= 1;
  while (ETH0->BUS_MODE & 1) (void) 0;

  // set clock rate
  ETH0->GMII_ADDRESS = get_clock_rate(d) << 2;

  // init phy
  struct mg_phy phy = {eth_read_phy, eth_write_phy};
  mg_phy_init(&phy, d->phy_addr, MG_PHY_CLOCKS_MAC);

  // configure MAC: DO, DM, FES, TC
  ETH0->MAC_CONFIGURATION = MG_BIT(13) | MG_BIT(11) | MG_BIT(14) | MG_BIT(24);

  // set the MAC address
  ETH0->MAC_ADDRESS0_HIGH = MG_U32(0, 0, ifp->mac[5], ifp->mac[4]);
  ETH0->MAC_ADDRESS0_LOW = 
        MG_U32(ifp->mac[3], ifp->mac[2], ifp->mac[1], ifp->mac[0]);

  // Configure the receive filter
  ETH0->MAC_FRAME_FILTER = MG_BIT(10) | MG_BIT(2); // HFP, HMC
  // Disable flow control
  ETH0->FLOW_CONTROL = 0;
  // Enable store and forward mode
  ETH0->OPERATION_MODE = MG_BIT(25) | MG_BIT(21); // RSF, TSF

  // Configure DMA bus mode (AAL, USP, RPBL, PBL)
  ETH0->BUS_MODE = MG_BIT(25) | MG_BIT(23) | (32 << 17) |  (32 << 8);

  // init RX descriptors
  for (int i = 0; i < ETH_DESC_CNT; i++) {
    s_rxdesc[i][0] = MG_BIT(31); // OWN descriptor
    s_rxdesc[i][1] = MG_BIT(14) | ETH_PKT_SIZE;
    s_rxdesc[i][2] = (uint32_t) s_rxbuf[i];
    if (i == ETH_DESC_CNT - 1) {
      s_rxdesc[i][3] = (uint32_t) &s_rxdesc[0][0];
    } else {
      s_rxdesc[i][3] = (uint32_t) &s_rxdesc[i + 1][0];
    }
  }
  ETH0->RECEIVE_DESCRIPTOR_LIST_ADDRESS = (uint32_t) &s_rxdesc[0][0];

  // init TX descriptors
  for (int i = 0; i < ETH_DESC_CNT; i++) {
    s_txdesc[i][0] = MG_BIT(30) | MG_BIT(20);
    s_txdesc[i][2] = (uint32_t) s_txbuf[i];
    if (i == ETH_DESC_CNT - 1) {
      s_txdesc[i][3] = (uint32_t) &s_txdesc[0][0];
    } else {
      s_txdesc[i][3] = (uint32_t) &s_txdesc[i + 1][0];
    }
  }
  ETH0->TRANSMIT_DESCRIPTOR_LIST_ADDRESS = (uint32_t) &s_txdesc[0][0];

  // Clear interrupts
  ETH0->STATUS = 0xFFFFFFFF;

  // Disable MAC interrupts
  ETH0->MMC_TRANSMIT_INTERRUPT_MASK = 0xFFFFFFFF;
  ETH0->MMC_RECEIVE_INTERRUPT_MASK = 0xFFFFFFFF;
  ETH0->MMC_IPC_RECEIVE_INTERRUPT_MASK = 0xFFFFFFFF;
  ETH0->INTERRUPT_MASK = MG_BIT(9) | MG_BIT(3); // TSIM, PMTIM

  //Enable interrupts (NIE, RIE, TIE)
  ETH0->INTERRUPT_ENABLE = MG_BIT(16) | MG_BIT(6) | MG_BIT(0);

  // Enable MAC transmission and reception (TE, RE)
  ETH0->MAC_CONFIGURATION |= MG_BIT(3) | MG_BIT(2);
  // Enable DMA transmission and reception (ST, SR)
  ETH0->OPERATION_MODE |= MG_BIT(13) | MG_BIT(1);
  return true;
}

static size_t mg_tcpip_driver_xmc_tx(const void *buf, size_t len,
                                        struct mg_tcpip_if *ifp) {
  if (len > sizeof(s_txbuf[s_txno])) {
    MG_ERROR(("Frame too big, %ld", (long) len));
    len = 0;  // Frame is too big
  } else if ((s_txdesc[s_txno][0] & MG_BIT(31))) {
    ifp->nerr++;
    MG_ERROR(("No free descriptors"));
    len = 0;  // All descriptors are busy, fail
  } else {
    memcpy(s_txbuf[s_txno], buf, len);
    s_txdesc[s_txno][1] = len;
    // Table 13-19 Transmit Descriptor Word 0 (IC, LS, FS, TCH)
    s_txdesc[s_txno][0] = MG_BIT(30) | MG_BIT(29) | MG_BIT(28) | MG_BIT(20);
    s_txdesc[s_txno][0] |= MG_BIT(31);  // OWN bit: handle control to DMA
    if (++s_txno >= ETH_DESC_CNT) s_txno = 0;
  }

  // Resume processing
  ETH0->STATUS = MG_BIT(2); // clear Transmit unavailable
  ETH0->TRANSMIT_POLL_DEMAND = 0;
  return len;
}

static bool mg_tcpip_driver_xmc_poll(struct mg_tcpip_if *ifp, bool s1) {
  if (!s1) return false;
  struct mg_tcpip_driver_xmc_data *d =
      (struct mg_tcpip_driver_xmc_data *) ifp->driver_data;
  uint8_t speed = MG_PHY_SPEED_10M;
  bool up = false, full_duplex = false;
  struct mg_phy phy = {eth_read_phy, eth_write_phy};
  up = mg_phy_up(&phy, d->phy_addr, &full_duplex, &speed);
  if ((ifp->state == MG_TCPIP_STATE_DOWN) && up) {  // link state just went up
    MG_DEBUG(("Link is %uM %s-duplex", speed == MG_PHY_SPEED_10M ? 10 : 100,
              full_duplex ? "full" : "half"));
  }
  return up;
}

void ETH0_0_IRQHandler(void);
void ETH0_0_IRQHandler(void) {
  uint32_t irq_status = ETH0->STATUS;

  // check if a frame was received
  if (irq_status & MG_BIT(6)) {
    for (uint8_t i = 0; i < 10; i++) { // read as they arrive, but not forever
      if (s_rxdesc[s_rxno][0] & MG_BIT(31)) break;
      size_t len = (s_rxdesc[s_rxno][0] & 0x3fff0000) >> 16;
      mg_tcpip_qwrite(s_rxbuf[s_rxno], len, s_ifp);
      s_rxdesc[s_rxno][0] = MG_BIT(31);   // OWN bit: handle control to DMA
      // Resume processing
      ETH0->STATUS = MG_BIT(7) | MG_BIT(6); // clear RU and RI
      ETH0->RECEIVE_POLL_DEMAND = 0;
      if (++s_rxno >= ETH_DESC_CNT) s_rxno = 0;
    }
    ETH0->STATUS = MG_BIT(6);
  }

  // clear Successful transmission interrupt
  if (irq_status & 1) {
    ETH0->STATUS = 1;
  }

  // clear normal interrupt
  if (irq_status & MG_BIT(16)) {
    ETH0->STATUS = MG_BIT(16);
  }
}

struct mg_tcpip_driver mg_tcpip_driver_xmc = {
    mg_tcpip_driver_xmc_init, mg_tcpip_driver_xmc_tx, NULL,
    mg_tcpip_driver_xmc_poll};
#endif

#ifdef MG_ENABLE_LINES
#line 1 "src/drivers/xmc7.c"
#endif


#if MG_ENABLE_TCPIP && defined(MG_ENABLE_DRIVER_XMC7) && MG_ENABLE_DRIVER_XMC7

struct ETH_Type {
  volatile uint32_t CTL, STATUS, RESERVED[1022], NETWORK_CONTROL,
      NETWORK_CONFIG, NETWORK_STATUS, USER_IO_REGISTER, DMA_CONFIG,
      TRANSMIT_STATUS, RECEIVE_Q_PTR, TRANSMIT_Q_PTR, RECEIVE_STATUS,
      INT_STATUS, INT_ENABLE, INT_DISABLE, INT_MASK, PHY_MANAGEMENT, PAUSE_TIME,
      TX_PAUSE_QUANTUM, PBUF_TXCUTTHRU, PBUF_RXCUTTHRU, JUMBO_MAX_LENGTH,
      EXTERNAL_FIFO_INTERFACE, RESERVED1, AXI_MAX_PIPELINE, RSC_CONTROL,
      INT_MODERATION, SYS_WAKE_TIME, RESERVED2[7], HASH_BOTTOM, HASH_TOP,
      SPEC_ADD1_BOTTOM, SPEC_ADD1_TOP, SPEC_ADD2_BOTTOM, SPEC_ADD2_TOP,
      SPEC_ADD3_BOTTOM, SPEC_ADD3_TOP, SPEC_ADD4_BOTTOM, SPEC_ADD4_TOP,
      SPEC_TYPE1, SPEC_TYPE2, SPEC_TYPE3, SPEC_TYPE4, WOL_REGISTER,
      STRETCH_RATIO, STACKED_VLAN, TX_PFC_PAUSE, MASK_ADD1_BOTTOM,
      MASK_ADD1_TOP, DMA_ADDR_OR_MASK, RX_PTP_UNICAST, TX_PTP_UNICAST,
      TSU_NSEC_CMP, TSU_SEC_CMP, TSU_MSB_SEC_CMP, TSU_PTP_TX_MSB_SEC,
      TSU_PTP_RX_MSB_SEC, TSU_PEER_TX_MSB_SEC, TSU_PEER_RX_MSB_SEC,
      DPRAM_FILL_DBG, REVISION_REG, OCTETS_TXED_BOTTOM, OCTETS_TXED_TOP,
      FRAMES_TXED_OK, BROADCAST_TXED, MULTICAST_TXED, PAUSE_FRAMES_TXED,
      FRAMES_TXED_64, FRAMES_TXED_65, FRAMES_TXED_128, FRAMES_TXED_256,
      FRAMES_TXED_512, FRAMES_TXED_1024, FRAMES_TXED_1519, TX_UNDERRUNS,
      SINGLE_COLLISIONS, MULTIPLE_COLLISIONS, EXCESSIVE_COLLISIONS,
      LATE_COLLISIONS, DEFERRED_FRAMES, CRS_ERRORS, OCTETS_RXED_BOTTOM,
      OCTETS_RXED_TOP, FRAMES_RXED_OK, BROADCAST_RXED, MULTICAST_RXED,
      PAUSE_FRAMES_RXED, FRAMES_RXED_64, FRAMES_RXED_65, FRAMES_RXED_128,
      FRAMES_RXED_256, FRAMES_RXED_512, FRAMES_RXED_1024, FRAMES_RXED_1519,
      UNDERSIZE_FRAMES, EXCESSIVE_RX_LENGTH, RX_JABBERS, FCS_ERRORS,
      RX_LENGTH_ERRORS, RX_SYMBOL_ERRORS, ALIGNMENT_ERRORS, RX_RESOURCE_ERRORS,
      RX_OVERRUNS, RX_IP_CK_ERRORS, RX_TCP_CK_ERRORS, RX_UDP_CK_ERRORS,
      AUTO_FLUSHED_PKTS, RESERVED3, TSU_TIMER_INCR_SUB_NSEC, TSU_TIMER_MSB_SEC,
      TSU_STROBE_MSB_SEC, TSU_STROBE_SEC, TSU_STROBE_NSEC, TSU_TIMER_SEC,
      TSU_TIMER_NSEC, TSU_TIMER_ADJUST, TSU_TIMER_INCR, TSU_PTP_TX_SEC,
      TSU_PTP_TX_NSEC, TSU_PTP_RX_SEC, TSU_PTP_RX_NSEC, TSU_PEER_TX_SEC,
      TSU_PEER_TX_NSEC, TSU_PEER_RX_SEC, TSU_PEER_RX_NSEC, PCS_CONTROL,
      PCS_STATUS, RESERVED4[2], PCS_AN_ADV, PCS_AN_LP_BASE, PCS_AN_EXP,
      PCS_AN_NP_TX, PCS_AN_LP_NP, RESERVED5[6], PCS_AN_EXT_STATUS, RESERVED6[8],
      TX_PAUSE_QUANTUM1, TX_PAUSE_QUANTUM2, TX_PAUSE_QUANTUM3, RESERVED7,
      RX_LPI, RX_LPI_TIME, TX_LPI, TX_LPI_TIME, DESIGNCFG_DEBUG1,
      DESIGNCFG_DEBUG2, DESIGNCFG_DEBUG3, DESIGNCFG_DEBUG4, DESIGNCFG_DEBUG5,
      DESIGNCFG_DEBUG6, DESIGNCFG_DEBUG7, DESIGNCFG_DEBUG8, DESIGNCFG_DEBUG9,
      DESIGNCFG_DEBUG10, RESERVED8[22], SPEC_ADD5_BOTTOM, SPEC_ADD5_TOP,
      RESERVED9[60], SPEC_ADD36_BOTTOM, SPEC_ADD36_TOP, INT_Q1_STATUS,
      INT_Q2_STATUS, INT_Q3_STATUS, RESERVED10[11], INT_Q15_STATUS, RESERVED11,
      TRANSMIT_Q1_PTR, TRANSMIT_Q2_PTR, TRANSMIT_Q3_PTR, RESERVED12[11],
      TRANSMIT_Q15_PTR, RESERVED13, RECEIVE_Q1_PTR, RECEIVE_Q2_PTR,
      RECEIVE_Q3_PTR, RESERVED14[3], RECEIVE_Q7_PTR, RESERVED15,
      DMA_RXBUF_SIZE_Q1, DMA_RXBUF_SIZE_Q2, DMA_RXBUF_SIZE_Q3, RESERVED16[3],
      DMA_RXBUF_SIZE_Q7, CBS_CONTROL, CBS_IDLESLOPE_Q_A, CBS_IDLESLOPE_Q_B,
      UPPER_TX_Q_BASE_ADDR, TX_BD_CONTROL, RX_BD_CONTROL, UPPER_RX_Q_BASE_ADDR,
      RESERVED17[2], HIDDEN_REG0, HIDDEN_REG1, HIDDEN_REG2, HIDDEN_REG3,
      RESERVED18[2], HIDDEN_REG4, HIDDEN_REG5;
};

#define ETH0 ((struct ETH_Type *) 0x40490000)

#define ETH_PKT_SIZE 1536  // Max frame size
#define ETH_DESC_CNT 4     // Descriptors count
#define ETH_DS 2           // Descriptor size (words)

// TODO(): handle these in a portable compiler-independent CMSIS-friendly way
#define MG_8BYTE_ALIGNED __attribute__((aligned((8U))))

static uint8_t s_rxbuf[ETH_DESC_CNT][ETH_PKT_SIZE];
static uint8_t s_txbuf[ETH_DESC_CNT][ETH_PKT_SIZE];
static uint32_t s_rxdesc[ETH_DESC_CNT][ETH_DS] MG_8BYTE_ALIGNED;
static uint32_t s_txdesc[ETH_DESC_CNT][ETH_DS] MG_8BYTE_ALIGNED;
static uint8_t s_txno MG_8BYTE_ALIGNED;     // Current TX descriptor
static uint8_t s_rxno MG_8BYTE_ALIGNED;     // Current RX descriptor

static struct mg_tcpip_if *s_ifp;  // MIP interface
enum { MG_PHY_ADDR = 0, MG_PHYREG_BCR = 0, MG_PHYREG_BSR = 1 };

static uint16_t eth_read_phy(uint8_t addr, uint8_t reg) {
  // WRITE1, READ OPERATION, PHY, REG, WRITE10
  ETH0->PHY_MANAGEMENT = MG_BIT(30) | MG_BIT(29) | ((addr & 0xf) << 24) |
                         ((reg & 0x1f) << 18) | MG_BIT(17);
  while ((ETH0->NETWORK_STATUS & MG_BIT(2)) == 0) (void) 0;
  return ETH0->PHY_MANAGEMENT & 0xffff;
}

static void eth_write_phy(uint8_t addr, uint8_t reg, uint16_t val) {
  ETH0->PHY_MANAGEMENT = MG_BIT(30) | MG_BIT(28) | ((addr & 0xf) << 24) |
                         ((reg & 0x1f) << 18) | MG_BIT(17) | val;
  while ((ETH0->NETWORK_STATUS & MG_BIT(2)) == 0) (void) 0;
}

static uint32_t get_clock_rate(struct mg_tcpip_driver_xmc7_data *d) {
  // see ETH0 -> NETWORK_CONFIG register
  (void) d;
  return 3;
}

static bool mg_tcpip_driver_xmc7_init(struct mg_tcpip_if *ifp) {
  struct mg_tcpip_driver_xmc7_data *d =
      (struct mg_tcpip_driver_xmc7_data *) ifp->driver_data;
  s_ifp = ifp;

  // enable controller, set RGMII mode
  ETH0->CTL = MG_BIT(31) | (4 << 8) | 2;

  uint32_t cr = get_clock_rate(d);
  // set NSP change, ignore RX FCS, data bus width, clock rate
  // frame length 1536, full duplex, speed
  ETH0->NETWORK_CONFIG = MG_BIT(29) | MG_BIT(26) | MG_BIT(21) |
                         ((cr & 7) << 18) | MG_BIT(8) | MG_BIT(4) | MG_BIT(1) |
                         MG_BIT(0);

  // config DMA settings: Force TX burst, Discard on Error, set RX buffer size
  // to 1536, TX_PBUF_SIZE, RX_PBUF_SIZE, AMBA_BURST_LENGTH
  ETH0->DMA_CONFIG =
      MG_BIT(26) | MG_BIT(24) | (0x18 << 16) | MG_BIT(10) | (3 << 8) | 4;

  // initialize descriptors
  for (int i = 0; i < ETH_DESC_CNT; i++) {
    s_rxdesc[i][0] = (uint32_t) s_rxbuf[i];
    if (i == ETH_DESC_CNT - 1) {
      s_rxdesc[i][0] |= MG_BIT(1);  // mark last descriptor
    }

    s_txdesc[i][0] = (uint32_t) s_txbuf[i];
    s_txdesc[i][1] = MG_BIT(31);  // OWN descriptor
    if (i == ETH_DESC_CNT - 1) {
      s_txdesc[i][1] |= MG_BIT(30);  // mark last descriptor
    }
  }
  ETH0->RECEIVE_Q_PTR = (uint32_t) s_rxdesc;
  ETH0->TRANSMIT_Q_PTR = (uint32_t) s_txdesc;

  // disable other queues
  ETH0->TRANSMIT_Q2_PTR = 1;
  ETH0->TRANSMIT_Q1_PTR = 1;
  ETH0->RECEIVE_Q2_PTR = 1;
  ETH0->RECEIVE_Q1_PTR = 1;

  // enable interrupts (RX complete)
  ETH0->INT_ENABLE = MG_BIT(1);

  // set MAC address
  ETH0->SPEC_ADD1_BOTTOM =
      ifp->mac[3] << 24 | ifp->mac[2] << 16 | ifp->mac[1] << 8 | ifp->mac[0];
  ETH0->SPEC_ADD1_TOP = ifp->mac[5] << 8 | ifp->mac[4];

  // enable MDIO, TX, RX
  ETH0->NETWORK_CONTROL = MG_BIT(4) | MG_BIT(3) | MG_BIT(2);

  // start transmission
  ETH0->NETWORK_CONTROL |= MG_BIT(9);

  // init phy
  struct mg_phy phy = {eth_read_phy, eth_write_phy};
  mg_phy_init(&phy, d->phy_addr, MG_PHY_CLOCKS_MAC);

  (void) d;
  return true;
}

static size_t mg_tcpip_driver_xmc7_tx(const void *buf, size_t len,
                                      struct mg_tcpip_if *ifp) {
  if (len > sizeof(s_txbuf[s_txno])) {
    MG_ERROR(("Frame too big, %ld", (long) len));
    len = 0;  // Frame is too big
  } else if (((s_txdesc[s_txno][1] & MG_BIT(31)) == 0)) {
    ifp->nerr++;
    MG_ERROR(("No free descriptors"));
    len = 0;  // All descriptors are busy, fail
  } else {
    memcpy(s_txbuf[s_txno], buf, len);
    s_txdesc[s_txno][1] = (s_txno == ETH_DESC_CNT - 1 ? MG_BIT(30) : 0) |
                          MG_BIT(15) | len;  // Last buffer and length

    ETH0->NETWORK_CONTROL |= MG_BIT(9);  // enable transmission
    if (++s_txno >= ETH_DESC_CNT) s_txno = 0;
  }

  MG_DSB();
  ETH0->TRANSMIT_STATUS = ETH0->TRANSMIT_STATUS;
  ETH0->NETWORK_CONTROL |= MG_BIT(9);  // enable transmission

  return len;
}

static bool mg_tcpip_driver_xmc7_poll(struct mg_tcpip_if *ifp, bool s1) {
  if (!s1) return false;
  struct mg_tcpip_driver_xmc7_data *d =
      (struct mg_tcpip_driver_xmc7_data *) ifp->driver_data;
  uint8_t speed = MG_PHY_SPEED_10M;
  bool up = false, full_duplex = false;
  struct mg_phy phy = {eth_read_phy, eth_write_phy};
  up = mg_phy_up(&phy, d->phy_addr, &full_duplex, &speed);
  if ((ifp->state == MG_TCPIP_STATE_DOWN) && up) {  // link state just went up
    // tmp = reg with flags set to the most likely situation: 100M full-duplex
    // if(link is slow or half) set flags otherwise
    // reg = tmp
    uint32_t netconf = ETH0->NETWORK_CONFIG;
    MG_SET_BITS(netconf, MG_BIT(10),
                MG_BIT(1) | MG_BIT(0));  // 100M, Full-duplex
    uint32_t ctl = ETH0->CTL;
    MG_SET_BITS(ctl, 0xFF00, 4 << 8);  // /5 for 25M clock
    if (speed == MG_PHY_SPEED_1000M) {
      netconf |= MG_BIT(10);        // 1000M
      MG_SET_BITS(ctl, 0xFF00, 0);  // /1 for 125M clock TODO() IS THIS NEEDED ?
    } else if (speed == MG_PHY_SPEED_10M) {
      netconf &= ~MG_BIT(0);         // 10M
      MG_SET_BITS(ctl, 0xFF00, 49);  // /50 for 2.5M clock
    }
    if (full_duplex == false) netconf &= ~MG_BIT(1);  // Half-duplex
    ETH0->NETWORK_CONFIG = netconf;  // IRQ handler does not fiddle with these
    ETH0->CTL = ctl;
    MG_DEBUG(("Link is %uM %s-duplex",
              speed == MG_PHY_SPEED_10M
                  ? 10
                  : (speed == MG_PHY_SPEED_100M ? 100 : 1000),
              full_duplex ? "full" : "half"));
  }
  return up;
}

void ETH_IRQHandler(void) {
  uint32_t irq_status = ETH0->INT_STATUS;
  if (irq_status & MG_BIT(1)) {
    for (uint8_t i = 0; i < 10; i++) { // read as they arrive, but not forever
      if ((s_rxdesc[s_rxno][0] & MG_BIT(0)) == 0) break;
      size_t len = s_rxdesc[s_rxno][1] & (MG_BIT(13) - 1);
      mg_tcpip_qwrite(s_rxbuf[s_rxno], len, s_ifp);
      s_rxdesc[s_rxno][0] &= ~MG_BIT(0);  // OWN bit: handle control to DMA
      if (++s_rxno >= ETH_DESC_CNT) s_rxno = 0;
    }
  }

  ETH0->INT_STATUS = irq_status;
}

struct mg_tcpip_driver mg_tcpip_driver_xmc7 = {mg_tcpip_driver_xmc7_init,
                                               mg_tcpip_driver_xmc7_tx, NULL,
                                               mg_tcpip_driver_xmc7_poll};
#endif