termios & binary data

[Eric Norum]

Geoffroy Montel <g_montel at yahoo.com> wrote:
> Hello,
>
> Termios is cool for console purpose, it works well (thanks Eric).
> But now I'd like to add quick binary I/O in my bsp. First I thought
> about
> doing another serial driver, but Joel adviced me to ask about
> termios & binary data. Besides it would be better having a single
> driver!
>
> So, as, I quote termio man page, "Normally, terminal input is
> processed in
> units of lines", how could we do binary I/O with termios? There's a
> non-canonical mode input processing, but is it implemented?
>
> I also would need these things:
> 1. read a given number of bytes from an uart
> 2. blocking/non-blocking read

For raw output, just turn off OPOST.  For raw input turn off  
echoing, ISTRIP and ICANON.  For blocking/non-blocking/timed input,  
set c_cc[VMIN] and c_cc[VCTIME] appropriately.  There is some  
overhead involved in going through the termios driver for raw I/O,  
but I'm willing to take the performance hit for the flexibility of  
being able to use familiar POSIX terminal handling code in my  
application.

Here's some of the code I used to test the termios driver:

/*
 * Test raw (ICANON=0) input
 */
static void
testRawInput (int vmin, int vtime)
{
        int i;
        struct termios old, new;
        rtems_interval ticksPerSecond, then, now;
        unsigned int msec;
        unsigned long count;
        int nread;
        unsigned char cbuf[100];

        printf ("*** Raw input  VMIN=%d  VTIME=%d ***\n", vmin, vtime);
        rtems_clock_get (RTEMS_CLOCK_GET_TICKS_PER_SECOND,  
&ticksPerSecond);
        i = tcgetattr (fileno (stdin), &old);
        if (i < 0) {
                printf ("tcgetattr failed: %s\n", strerror (errno));
                return;
        }
        new = old;
        new.c_lflag &= ~(ICANON | ECHO | ECHONL | ECHOK | ECHOE |  
ECHOPRT | ECHOCTL);
        new.c_cc[VMIN] = vmin;
        new.c_cc[VTIME] = vtime;
        i = tcsetattr (fileno (stdin), TCSANOW, &new);
        if (i < 0) {
                printf ("tcsetattr failed: %s\n", strerror (errno));
                return;
        }
        do {
                rtems_clock_get (RTEMS_CLOCK_GET_TICKS_SINCE_BOOT, &then);
                count = 0;
                for (;;) {
                        nread = read (fileno (stdin), cbuf, sizeof cbuf);
                        if (nread < 0) {
                                printf ("Read error: %s\n", strerror  
(errno));
                                goto out;
                        }
                        count++;
                        if (nread != 0)
                                break;
                }
                rtems_clock_get (RTEMS_CLOCK_GET_TICKS_SINCE_BOOT, &now);
                msec = (now - then) * 1000 / ticksPerSecond;
                printf ("Count:%-10lu  Interval:%3u.%3.3d  Char:",
                                        count, msec / 1000, msec % 1000);
                for (i = 0 ; i < nread ; i++)
                        printf (" %2.2x", cbuf[i]);
                printf ("\n");
        } while (cbuf[0] != 'q');
    out:
        i = tcsetattr (fileno (stdin), TCSANOW, &old);
        if (i < 0)
                printf ("tcsetattr failed: %s\n", strerror (errno));
}

.
.
.
.
                testRawInput (0, 0);
                testRawInput (0, 20);
                testRawInput (5, 0);
                testRawInput (5, 20);

---
Eric Norum                                 eric at skatter.usask.ca
Saskatchewan Accelerator Laboratory        Phone: (306) 966-6308
University of Saskatchewan                 FAX:   (306) 966-6058
Saskatoon, Canada.