[LinuxPPS] setting an offset

[James Boddington]

Rodolfo Giometti wrote:
> On Wed, Mar 26, 2008 at 10:35:16AM +1000, James Boddington wrote:
>> Is there any documentation for setting a static offset with linuxpps? Looking 
>> at the code it seems to be supported.
> 
> No. But you can take a look at RFC.

Had a look at the RFC. Was easy enough to do. If anyone else is interested this 
is what I did as a quick test.

#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <linux/pps.h>

main()

{
     int fd;
     struct pps_kparams params;

     fd = open("/dev/pps0", O_RDWR);
     if (fd < 0) {
         printf("Oh...\n");
         exit(1);
     }

     /* show current offset */
     ioctl(fd, PPS_GETPARAMS, &params);
     printf(" sec %ld\n", params.assert_off_tu.sec);
     printf("nsec %d\n", params.assert_off_tu.nsec);

     /* set a 1ms offset */
     params.mode |= PPS_OFFSETASSERT;
     params.assert_off_tu.sec = 0;        /* offset seconds */
     params.assert_off_tu.nsec = 1000000; /* offset nanoseconds */
     ioctl(fd, PPS_SETPARAMS, &params);

     /* show offset again to verify change */
     ioctl(fd, PPS_GETPARAMS, &params);
     printf(" sec %ld\n", params.assert_off_tu.sec);
     printf("nsec %d\n", params.assert_off_tu.nsec);

     close(fd);
}

-- 
    James