I just cannot get exclusive access to the parport, there still seems to be
some noise getting out the parallel port pins.
I used ioctl(), in the following piece of code:
/*
* User-space parport hogger (for stress-testing parport).
*
* Copyright (c) 1998 Tim Waugh <tim@cyberelk.demon.co.uk>
*/
#include <time.h>
#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <linux/ppdev.h>
int main (int argc, char * argv [])
{
int p;
/* Check we've been told which device to open */
if (argc < 2) {
fprintf (stderr, "Hog which parport???\n");
return 1;
}
/* Open the device */
p = open (argv[1], O_EXCL);
if (p < 0) {
fprintf (stderr, "Couldn't open %s\n", argv[1]);
return 2;
}
/* Now hog the port. */
for (;;) {
const struct timespec w = {5, 250000000}; /* 250ms */
/* Claim the port */
if (ioctl (p, PPEXCL,0)) {
printf ("I guess i couldn't get exclusive.\n");
continue;
}
if (ioctl (p, PPCLAIM, 0)) {
printf ("Couldn't claim port!\n");
continue;
}
/* Wait for a while */
nanosleep (&w, NULL);
/* Release the port */
if (ioctl (p, PPRELEASE, 0))
printf ("Couldn't release port!\n");
putchar ('.');
fflush(NULL);
}
return 0;
}
I don't get any error, everything works fine, but even after aquiring the
port in EXCLUSIVE mode, i still get signal noise or something out of the
parallel port.
I do not have any problem as such under Windoze platform (but W. is
useless to me).
Can anyone help?
----------------------------
ataraxis@disponibil.net
lucian@psdtimis.ro
0740.959.300
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