serial_open.c

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/*
 * This file is part of the Fun programming language.
 * https://fun-lang.xyz/
 *
 * Copyright 2025 Johannes Findeisen <you@hanez.org>
 * Licensed under the terms of the Apache-2.0 license.
 * https://opensource.org/license/apache-2-0
 */


#ifdef __unix__
#include <fcntl.h>
#include <termios.h>
#include <unistd.h>

/* Fallbacks for baud rates that might be missing on some systems */
#ifndef B50
#define B50 0000001
#endif
#ifndef B75
#define B75 0000002
#endif
#ifndef B110
#define B110 0000003
#endif
#ifndef B134
#define B134 0000004
#endif
#ifndef B150
#define B150 0000005
#endif
#ifndef B200
#define B200 0000006
#endif
#ifndef B300
#define B300 0000007
#endif
#ifndef B600
#define B600 0000010
#endif
#ifndef B1200
#define B1200 0000011
#endif
#ifndef B1800
#define B1800 0000012
#endif
#ifndef B2400
#define B2400 0000013
#endif
#ifndef B4800
#define B4800 0000014
#endif
#ifndef B9600
#define B9600 0000015
#endif
#ifndef B19200
#define B19200 0000016
#endif
#ifndef B38400
#define B38400 0000017
#endif
#ifndef B57600
#define B57600 0010001
#endif
#ifndef B115200
#define B115200 0010002
#endif
#ifndef B230400
#define B230400 0010003
#endif

#ifndef O_NDELAY
#define O_NDELAY O_NONBLOCK
#endif
#endif

case OP_SERIAL_OPEN: {
 /* Pops baud_rate (int), path (string); returns fd (int) or 0 */
 Value baudv = pop_value(vm);
 Value pathv = pop_value(vm);
 int fd = 0;
#ifdef __unix__
 if (baudv.type != VAL_INT || pathv.type != VAL_STRING) {
 fprintf(stderr, "Runtime type error: serial_open expects (string path, int baud_rate)\n");
 free_value(baudv);
 free_value(pathv);
 push_value(vm, make_int(0));
 break;
 }

 const char *path = pathv.s ? pathv.s : "";
 int baud = (int)baudv.i;
 speed_t speed;

 switch (baud) {
 case 50:
 speed = B50;
 break;
 case 75:
 speed = B75;
 break;
 case 110:
 speed = B110;
 break;
 case 134:
 speed = B134;
 break;
 case 150:
 speed = B150;
 break;
 case 200:
 speed = B200;
 break;
 case 300:
 speed = B300;
 break;
 case 600:
 speed = B600;
 break;
 case 1200:
 speed = B1200;
 break;
 case 1800:
 speed = B1800;
 break;
 case 2400:
 speed = B2400;
 break;
 case 4800:
 speed = B4800;
 break;
 case 9600:
 speed = B9600;
 break;
 case 19200:
 speed = B19200;
 break;
 case 38400:
 speed = B38400;
 break;
 case 57600:
 speed = B57600;
 break;
 case 115200:
 speed = B115200;
 break;
 case 230400:
 speed = B230400;
 break;
 default:
 speed = B9600;
 break;
 }

 fd = open(path, O_RDWR | O_NOCTTY | O_NDELAY);
 if (fd != -1) {
 struct termios options;
 tcgetattr(fd, &options);
 cfsetispeed(&options, speed);
 cfsetospeed(&options, speed);
 options.c_cflag |= (CLOCAL | CREAD);
 options.c_cflag &= ~PARENB;
 options.c_cflag &= ~CSTOPB;
 options.c_cflag &= ~CSIZE;
 options.c_cflag |= CS8;
 options.c_lflag &= ~(ICANON | ECHO | ECHOE | ISIG);
 options.c_iflag &= ~(IXON | IXOFF | IXANY);
 options.c_oflag &= ~OPOST;
 tcsetattr(fd, TCSANOW, &options);
 fcntl(fd, F_SETFL, 0); // block on read
 } else {
 fd = 0;
 }
#endif
 free_value(baudv);
 free_value(pathv);
 push_value(vm, make_int(fd > 0 ? fd : 0));
 break;
}