DragonFlyBSD

#include <stdlib.h>

#include <stdio.h>

#include <stddef.h>

#include <unistd.h>

#include <string.h>

#include <fcntl.h>

#include <errno.h>

#include <termios.h>

#include <sys/ioctl.h>

#include <sys/stat.h>

#if defined(__linux__)

# define MODEM "/dev/ttyACM0"

#elif defined(__APPLE__)

# define MODEM "/dev/cu.usbmodem0000001"

#elif defined(__NetBSD__)

# define MODEM "/dev/dtyU0"

#elif defined(__bsdi__) || defined(__DragonFly__)

# define MODEM "/dev/cuaU0"

#endif

static void make_blocking(int fd)

{

    const int old = fcntl(fd, F_GETFL, 0);

    fcntl(fd, F_SETFL, old & ~(int)O_NONBLOCK);

}

static void make_nonblocking(int fd)

{

    const int old = fcntl(fd, F_GETFL, 0);

    fcntl(fd, F_SETFL, old | (int)O_NONBLOCK);

}

/* gcc -Wall -g3 -O1 -std=c99 test.c -o test.exe */

int main(int argc, char* argv[])

{

    int fd = open(MODEM, O_RDWR | O_NOCTTY | O_SYNC);

    if (fd == -1) {

        printf("open failed\n");

        goto finish;

    }

    printf("Setting TIOCEXCL\n");

    /* Mark the fd as exclusive so ModemManager     */

    /* and friends cannot open and muck with state. */

    if (ioctl(fd, TIOCEXCL, NULL) == -1) {

        printf("ioctl failed\n");

        goto finish;

    }

    printf("Getting tty\n");

    struct termios tty;

    if (tcgetattr(fd, &tty) != 0) {

        printf("tcgetattr failed\n");

        goto finish;

    }

    printf("Setting tty options\n");

    cfmakeraw(&tty);

    tty.c_cflag |= (CLOCAL | CRTSCTS);

    // tty.c_cflag &= ~CSTOPB;  /* 1 stop bit */

    // tty.c_cflag |=  CSTOPB;  /* 2 stop bit */

    cfsetospeed(&tty, B57600);

    cfsetispeed(&tty, B57600);

    printf("Flushing tty\n");

    if (tcflush(fd, TCIOFLUSH) != 0) {

        printf("tcflush failed\n");

        goto finish;

    }

    printf("Setting tty\n");

    if (tcsetattr(fd, TCSANOW, &tty) != 0) {

        printf("tcsetattr failed\n");

        goto finish;

    }

    /*********** Write ***********/

    printf("Writing ATZ\n");

    ssize_t res = write(fd, "ATZ\r", 4);

    if (res == -1) {

        printf("write failed\n");

        goto finish;

    }

    printf("Waiting for write\n");

    res = tcdrain(fd);

    if (res == -1) {

        printf("tcdrain failed\n");

        goto finish;

    }

    printf("Wrote: ATZ\n");

    /*********** Read ***********/

    printf("Reading response\n");

    make_blocking(fd);

    for ( ; ; )

    {

        unsigned char buf[512];

        res = read(fd, buf, sizeof(buf));

        if (res == -1 && errno == EWOULDBLOCK) {

            break;

        }

        else if (res == -1) {

            printf("read failed\n");

            goto finish;

        }

        make_nonblocking(fd);

        buf[res] = '\0';

        printf("Read: %s\n", buf);

    }

finish:

    if (fd != -1)

        close(fd);

    return 0;

}