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formathttpdatetime.c
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/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2020 Justine Alexandra Roberts Tunney │
│ │
│ Permission to use, copy, modify, and/or distribute this software for │
│ any purpose with or without fee is hereby granted, provided that the │
│ above copyright notice and this permission notice appear in all copies. │
│ │
│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
│ PERFORMANCE OF THIS SOFTWARE. │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/macros.internal.h"
#include "libc/str/str.h"
#include "libc/time/struct/tm.h"
#include "libc/time/time.h"
#include "net/http/http.h"
/**
* Formats HTTP timestamp, e.g.
*
* Sun, 04 Oct 2020 19:50:10 GMT
*
* This function is the same as:
*
* strftime(p, 30, "%a, %d %b %Y %H:%M:%S %Z", tm)
*
* Except this function goes 10x faster:
*
* FormatHttpDateTime l: 25𝑐 8𝑛𝑠
* strftime l: 709𝑐 229𝑛𝑠
*
* @param tm must be zulu see gmtime_r() and nowl()
* @see ParseHttpDateTime()
*/
char *FormatHttpDateTime(char p[hasatleast 30], struct tm *tm) {
unsigned i;
p = mempcpy(p, kWeekdayNameShort[tm->tm_wday], 3);
*p++ = ',';
*p++ = ' ';
i = MIN(MAX(tm->tm_mday, 1), 31);
*p++ = '0' + i / 10;
*p++ = '0' + i % 10;
*p++ = ' ';
i = MIN(MAX(tm->tm_mon, 0), 11);
p = mempcpy(p, kMonthNameShort[i], 3);
*p++ = ' ';
i = MIN(MAX(tm->tm_year + 1900, 0), 9999);
*p++ = '0' + i / 1000;
*p++ = '0' + i / 100 % 10;
*p++ = '0' + i / 10 % 10;
*p++ = '0' + i % 10;
*p++ = ' ';
i = MIN(MAX(tm->tm_hour, 0), 23);
*p++ = '0' + i / 10;
*p++ = '0' + i % 10;
*p++ = ':';
i = MIN(MAX(tm->tm_min, 0), 59);
*p++ = '0' + i / 10;
*p++ = '0' + i % 10;
*p++ = ':';
i = MIN(MAX(tm->tm_sec, 0), 59);
*p++ = '0' + i / 10;
*p++ = '0' + i % 10;
*p++ = ' ';
*p++ = 'G';
*p++ = 'M';
*p++ = 'T';
*p = '\0';
return p;
}