#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>

#include <errno.h>
#include <fcntl.h>
#include <pthread.h>
#include <termios.h>
#include <unistd.h>
#include <sys/time.h>
#include <sys/select.h>


/**  Reads the serial port, implementing a timeout.
 *
 * @param serialfd Fd returned earlier from serial_init (...)
 * @param buffer The destination address for received bytes.
 * @param buflen The maximum amount of space available in the buffer.
 * @param timeout_ms Timeout in milliseconds; zero to poll, -ve for infinite.
 *
 * @return -1 if error, 0 if timeout before any data rx'd, else num
 * bytes placed into buffer (up to max of buflen).
 *
 * @todo Perhaps implement win32 style serial handling
 */

int serial_read_with_timeout (int serialfd, void *buffer, int buflen, int timeout_ms)
{
struct timeval tmo, *tmoptr;
int rv;
fd_set readfds;

//fd_set dummy1, dummy2;
    //FD_ZERO (&dummy1); FD_ZERO (&dummy2);

    FD_ZERO (&readfds);
    FD_SET (serialfd, &readfds);
    tmo.tv_sec = timeout_ms / 1000;
    tmo.tv_usec = (timeout_ms - (1000 * tmo.tv_sec)) * 1000;
    tmoptr = (timeout_ms < 0) ? NULL : &tmo;
    printf ("b4sel %d, %p, 0, 0, %p { %ld, %ld }\n", 1+serialfd, &readfds, tmoptr, tmo.tv_sec, tmo.tv_usec);
    rv = select (1 + serialfd, &readfds, NULL, NULL, tmoptr);
    //rv = select (1 + serialfd, &readfds, &dummy1, &dummy2, tmoptr);
    printf ("afsel\n");
    // So what happened? rv is 0 => no fd set, -1 = error, else there must be readable data
    if (rv <= 0)
        return rv;
    // huzzah! there is some data to actually read....
    // we could always do int bytes; ioctl(fd, FIONREAD, &bytes);
    // at this point, but nonblocking means we should be ok anyway.......
    rv = read (serialfd, buffer, buflen);
    return rv;
}



int main (int argc, const char **argv)
{
int rv, fd;
char buff[8];
struct termios tio;


    fd = open ("/dev/com1", O_RDWR | O_BINARY | /* O_NONBLOCK | */ O_NOCTTY | O_NDELAY );
    if (fd < 0)
    {
        fprintf (stderr, "oops error opening com1 %d\n", errno);
        return -1;
    }
    // Dunno for sure if this just duplicates setting O_NONBLOCK
    fcntl(fd, F_SETFL, FNDELAY);
    // Set the serial port to the baud rate chosen and 8n1.
    rv = tcgetattr (fd, &tio);
    if (rv)
    {
        fprintf (stderr, "Can't get options - error %d\n", errno);
        close (fd);
        return -1;
    }
    // Not implemented.... cfmakeraw (&tio); ... equivalent is....
    tio.c_iflag &= ~(IGNBRK|BRKINT|PARMRK|ISTRIP|INLCR|IGNCR|ICRNL|IXON|IXOFF|IXANY|INPCK|IUCLC);
    tio.c_oflag &= ~OPOST;
    tio.c_lflag &= ~(ECHO|ECHONL|ICANON|ISIG|IEXTEN|ECHOE);
    tio.c_cflag &= ~(CSIZE|PARENB);
    tio.c_cflag |= CS8 | CLOCAL | CREAD;
    // Now modify the defaults with chosen settings.
    rv = cfsetospeed (&tio, B57600);
    if (!rv)
        rv = cfsetispeed (&tio, B57600);
    if  (rv)
        fprintf (stderr, "ERROR: Baud rate not recognized\n");
    tio.c_cflag = (tio.c_cflag & ~CSIZE) | CS8;
    tio.c_cflag = (tio.c_cflag & ~PARENB);
    tio.c_cflag = (tio.c_cflag & ~CSTOPB);
    // and implement those settings.
    rv = tcsetattr (fd, TCSANOW, &tio);
    if (rv)
    {
        fprintf (stderr, "Error %d setting options\n", errno);
        close (fd);
        return -1;
    }

    // so try reading it
    rv = serial_read_with_timeout (fd, buff, 1, 250);
    fprintf (stderr, "serial read: rv %d char $%02x\n", rv, (unsigned int)buff[0]);

    // we done now.
    rv = close (fd);
    fprintf (stderr, "close gives %d\n", fd);
    return 0;
}