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trs_uart.c
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trs_uart.c
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/*
* Copyright (c) 2000-2020, Timothy P. Mann
*
* Permission is hereby granted, free of charge, to any person
* obtaining a copy of this software and associated documentation
* files (the "Software"), to deal in the Software without
* restriction, including without limitation the rights to use, copy,
* modify, merge, publish, distribute, sublicense, and/or sell copies
* of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
/*
* Emulation of the Radio Shack TRS-80 Model I/III/4/4P serial port.
*/
#define _POSIX_C_SOURCE 200112L /* signal.h: sigemptyset(), ... */
#include <errno.h>
#include <termios.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/file.h>
#include <fcntl.h>
#include <string.h>
#include <signal.h>
#include "trs.h"
#include "trs_uart.h"
#ifndef FNONBLOCK
#define FNONBLOCK O_NONBLOCK
#endif
#define BUFSIZE 256
/*#define UARTDEBUG 1*/
/*#define UARTDEBUG2 1*/
#if __linux
char *trs_uart_name = "/dev/ttyS0";
#else
char *trs_uart_name = "/dev/tty00";
#endif
int trs_uart_switches =
0x7 | TRS_UART_NOPAR | TRS_UART_WORD8; /* Default: 9600 8N1 */
static int initialized = 0;
static struct {
int modem;
int switches;
int baud;
int status;
int control;
int idata;
int odata;
Uchar buf[BUFSIZE];
Uchar* bufp;
int bufleft;
int tstates;
int fd;
int fdflags;
struct termios t;
} uart;
static int trs_uart_wordbits[] = TRS_UART_WORDBITS_TABLE;
static float trs_uart_baud[] = TRS_UART_BAUD_TABLE;
static int
xlate_baud(int trs_baud)
{
switch (trs_baud) {
case TRS_UART_50:
return B50;
case TRS_UART_75:
return B75;
case TRS_UART_110:
return B110;
case TRS_UART_134:
return B134;
case TRS_UART_150:
return B150;
case TRS_UART_300:
return B300;
case TRS_UART_600:
return B600;
case TRS_UART_1200:
return B1200;
case TRS_UART_1800:
return B1800;
case TRS_UART_2000:
error("unix does not support 2000 baud, using 38400");
return B38400;
case TRS_UART_2400:
return B2400;
case TRS_UART_3600:
#ifdef B57600
error("unix does not support 3600 baud, using 57600");
return B57600;
#else
error("unix does not support 3600 baud");
return B0;
#endif
case TRS_UART_4800:
return B4800;
case TRS_UART_7200:
#ifdef B115200
error("unix does not support 7200 baud, using 115200");
return B115200;
#else
error("unix does not support 7200 baud");
return B0;
#endif
case TRS_UART_9600:
return B9600;
case TRS_UART_19200:
return B19200;
}
return B0; /* not reached */
}
void
trs_uart_init(int reset_button)
{
int err;
#if UARTDEBUG
debug("trs_uart_init\n");
#endif
if (initialized == 1 && uart.fd != -1) close(uart.fd);
if (trs_uart_name == NULL || trs_uart_name[0] == '\000') {
/* Emulate having no serial port */
initialized = -1;
return;
}
initialized = 1;
uart.fd = open(trs_uart_name, O_RDWR|O_NOCTTY|O_NONBLOCK);
if (uart.fd == -1) {
error("can't open %s: %s", trs_uart_name, strerror(errno));
initialized = -1;
return;
} else {
uart.fdflags = FNONBLOCK;
err = tcgetattr(uart.fd, &uart.t);
if (err < 0) {
error("can't get attributes of %s: %s", trs_uart_name, strerror(errno));
close(uart.fd);
initialized = uart.fd = -1;
return;
}
}
uart.t.c_iflag = 0;
uart.t.c_oflag = 0;
uart.t.c_lflag = 0;
memset(uart.t.c_cc, 0, sizeof(uart.t.c_cc));
/* Not readable from a user process on unix */
uart.modem = TRS_UART_CTS | TRS_UART_DSR | TRS_UART_CD;
uart.switches = (trs_model == 1) ? trs_uart_switches : 0xff;
/* arbitrary default */
uart.baud = -1;
trs_uart_baud_out((TRS_UART_9600 << 4) + TRS_UART_9600);
/* arbitrary default */
uart.control = -1;
trs_uart_control_out(TRS_UART_NOPAR | TRS_UART_WORD8 | TRS_UART_NOTBREAK |
TRS_UART_DTR | TRS_UART_RTS);
uart.status = TRS_UART_SENT;
trs_uart_snd_interrupt(1);
uart.bufp = uart.buf;
uart.bufleft = 0;
}
int
trs_uart_modem_in(void)
{
/* should poll hardware here, if we could */
if (initialized == 0) trs_uart_init(0);
if (initialized == -1) return 0xff;
#if UARTDEBUG2
debug("trs_uart_modem_in returns 0x%02x\n", uart.modem);
#endif
return uart.modem;
}
void
trs_uart_reset_out(int value)
{
#if UARTDEBUG
debug("trs_uart_reset_out\n");
#endif
if (initialized == 0) trs_uart_init(0);
if (initialized == -1) {
error("serial port emulation is not enabled");
return;
}
}
int
trs_uart_switches_in(void)
{
if (initialized == 0) trs_uart_init(0);
if (initialized == -1) return 0xff;
#if UARTDEBUG
debug("trs_uart_switches_in returns 0x%02x\n", uart.switches);
#endif
return uart.switches;
}
void
trs_uart_baud_out(int value)
{
int err;
int bits;
#if UARTDEBUG
debug("trs_uart_baud_out 0x%02x\n", value);
#endif
if (initialized == 1 && uart.baud == value) return;
if (initialized == 0) trs_uart_init(0);
if (initialized == -1) return;
uart.baud = value;
cfsetispeed(&uart.t, xlate_baud(TRS_UART_RCVBAUD(value)));
cfsetospeed(&uart.t, xlate_baud(TRS_UART_SNDBAUD(value)));
bits = 1 + trs_uart_wordbits[TRS_UART_WORDBITS(uart.control)] +
((uart.control & TRS_UART_NOPAR) ? 0 : 1) +
((uart.control & TRS_UART_STOP2) ? 2 : 1);
uart.tstates = (z80_state.clockMHz * 1000000.0 * bits)
/ trs_uart_baud[TRS_UART_SNDBAUD(value)];
#if UARTDEBUG
debug("total bits %d; tstates per word %d\n", bits, uart.tstates);
#endif
if (uart.fd != -1) {
err = tcsetattr(uart.fd, TCSADRAIN, &uart.t);
if (err == -1) {
error("can't set attributes of %s: %s", trs_uart_name, strerror(errno));
}
}
}
void
trs_uart_set_avail(int dummy)
{
uart.status |= TRS_UART_RCVD;
trs_uart_rcv_interrupt(1);
}
void
trs_uart_set_empty(int dummy)
{
uart.status |= TRS_UART_SENT;
trs_uart_snd_interrupt(1);
}
int
trs_uart_check_avail(void)
{
if (initialized == 1 && uart.bufleft == 0 && uart.fd != -1) {
/* check for data available */
int rc;
if (!(uart.fdflags & FNONBLOCK)) {
#if UARTDEBUG
debug("trs_uart nonblocking\n");
#endif
uart.fdflags |= FNONBLOCK;
fcntl(uart.fd, F_SETFL, uart.fdflags);
}
do {
rc = read(uart.fd, uart.buf, BUFSIZE);
} while (rc < 0 && errno == EINTR);
#if UARTDEBUG
#if !UARTDEBUG2
if (rc >= 0 || errno != EAGAIN)
#endif
debug("trs_uart read returns %d, errno %d\n", rc, errno);
#endif
if (rc < 0) {
if (errno != EAGAIN) {
error("can't read from %s: %s", trs_uart_name, strerror(errno));
}
rc = 0;
}
uart.bufp = uart.buf;
uart.bufleft = rc;
if (rc > 0) {
/* be sure events don't happen too fast */
trs_schedule_event(trs_uart_set_avail, 1, uart.tstates);
}
}
#if UARTDEBUG2
debug("trs_uart_check_avail returns %d\n", uart.bufleft);
#endif
return uart.bufleft;
}
int
trs_uart_status_in(void)
{
#if UARTDEBUG
static int oldstatus = -1;
#endif
if (initialized == 0) trs_uart_init(0);
if (initialized == -1) return 0xff;
trs_uart_check_avail();
#if UARTDEBUG
if (uart.status != oldstatus) {
debug("trs_uart_status_in returns 0x%02x\n", uart.status);
oldstatus = uart.status;
}
#endif
return uart.status;
}
void
trs_uart_control_out(int value)
{
int err;
int cflag = HUPCL|CREAD|CLOCAL;
#if UARTDEBUG
debug("trs_uart_control_out 0x%02x\n", value);
#endif
if (initialized == 1 && uart.control == value) return;
if (initialized == 0) trs_uart_init(0);
if (initialized == -1) return;
uart.control = value;
if (!(value & TRS_UART_EVENPAR)) cflag |= PARODD;
switch (value & TRS_UART_WORDMASK) {
case TRS_UART_WORD5:
cflag |= CS5;
break;
case TRS_UART_WORD6:
cflag |= CS6;
break;
case TRS_UART_WORD7:
cflag |= CS7;
break;
case TRS_UART_WORD8:
cflag |= CS8;
break;
}
if (value & TRS_UART_STOP2) cflag |= CSTOPB;
if (!(value & TRS_UART_NOPAR)) cflag |= PARENB;
uart.t.c_cflag = cflag;
if (uart.fd != -1) {
err = tcsetattr(uart.fd, TCSADRAIN, &uart.t);
if (err == -1) {
error("can't set attributes of %s: %s", trs_uart_name, strerror(errno));
}
}
if (!(value & TRS_UART_NOTBREAK) && uart.fd != -1) {
sigset_t set, oldset;
sigemptyset(&set);
sigaddset(&set, SIGALRM);
sigprocmask(SIG_BLOCK, &set, &oldset);
err = tcsendbreak(uart.fd, 0);
sigprocmask(SIG_SETMASK, &oldset, NULL);
if (err == -1) {
error("can't send break on %s: %s", trs_uart_name, strerror(errno));
}
}
}
int
trs_uart_data_in(void)
{
if (initialized == 0) trs_uart_init(0);
if (initialized == -1) return 0xff;
trs_uart_check_avail();
if (uart.status & TRS_UART_RCVD) {
uart.status &= ~TRS_UART_RCVD;
trs_uart_rcv_interrupt(0);
uart.bufleft--;
uart.idata = *uart.bufp++;
if (uart.bufleft) {
trs_schedule_event(trs_uart_set_avail, 1, uart.tstates);
}
}
#if UARTDEBUG
debug("trs_uart_data_in returns 0x%02x\n", uart.idata);
#endif
return uart.idata;
}
void
trs_uart_data_out(int value)
{
int err;
#if UARTDEBUG
debug("trs_uart_data_out 0x%02x\n", value);
#endif
if (initialized == 0) trs_uart_init(0);
if (initialized == -1) return;
uart.odata = value;
if (uart.fd != -1) {
for (;;) {
err = write(uart.fd, &uart.odata, 1);
if (err >= 0) return;
if (errno != EAGAIN) {
error("can't read from %s: %s", trs_uart_name, strerror(errno));
return;
}
/* Oops, here we didn't really want nonblocking i/o */
#if UARTDEBUG
debug("trs_uart blocking\n");
#endif
uart.fdflags &= ~FNONBLOCK;
fcntl(uart.fd, F_SETFL, uart.fdflags);
}
trs_uart_snd_interrupt(0);
trs_schedule_event(trs_uart_set_empty, 1, uart.tstates);
}
}