#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/timepps.h>

#define  filename "/dev/ttyS0"
#define DEBUG 0
#define PPS_ECHO 0

#define CLEAR_EDGE  1
#define ASSERT_EDGE 0

/* 
Vladimir Smotlacha, vs@cesnet.cz
21.12.2001
*/


	int fd;
	long last_sequence;
	struct timespec ts;	/* last timestamp */
	pps_params_t pps_params; /* pps parameters */
	pps_info_t pps_info;	/* last pps data */
	pps_handle_t handle;	/* pps handlebars */


init (int clear_edge)
{
	int capability;
	int edge;

	last_sequence = 0;
	fd = open (filename, O_RDWR, 0);
	time_pps_create(fd, &handle);
	if (time_pps_getcap(handle, &capability) < 0) {
		printf(
		    "time_pps_getcap failed: %m\n");
		return (0);
	}
	memset(&pps_params, 0, sizeof(pps_params_t));
	if (clear_edge)
		pps_params.mode = capability & PPS_CAPTURECLEAR;
	else
		pps_params.mode = capability & PPS_CAPTUREASSERT;
	if (!pps_params.mode) {
		printf(
		    "invalid capture edge %d\n",
		    !clear_edge);
		return (0);
	}
#ifdef PPS_ECHO
	pps_params.mode |= PPS_ECHOCLEAR;
#endif	
	pps_params.mode |= PPS_TSFMT_TSPEC;
	if (time_pps_setparams(handle, &pps_params) < 0) {
		printf(
		    "time_pps_setparams failed: %m\n");
		return (0);
	}
	edge = 0;	/* clear all previous binds */
	if (time_pps_kcbind(handle, PPS_KC_HARDPPS, edge,
				    PPS_TSFMT_TSPEC) < 0) {
			printf(
			    "time_pps_kcbind failed: %m\n");
			return (0);
	}
	time_pps_getparams(handle, &pps_params);
	printf("capability 0x%x version %d mode 0x%x\n",
		capability, pps_params.api_version,
		pps_params.mode);

	return (1);
}

/*
 * Get PPSAPI timestamps.
 *
 * Return 0 on failure and 1 on success.
 */
static int pps(void)
{
	struct timespec timeout;

	if (handle == 0)
		return (0);
	timeout.tv_sec = 0;
	timeout.tv_nsec = 0;
	if (time_pps_fetch(handle, PPS_TSFMT_TSPEC, &pps_info,
	    &timeout) < 0)
		return (0);
	if (pps_params.mode & PPS_CAPTUREASSERT) {
		if (pps_info.assert_sequence == last_sequence)
		    return (0);
		ts = pps_info.assert_timestamp;
		last_sequence = pps_info.assert_sequence;
	} else if (pps_params.mode & PPS_CAPTURECLEAR) {
		if (pps_info.clear_sequence == last_sequence)
		    return (0);
		ts = pps_info.clear_timestamp;
		last_sequence = pps_info.clear_sequence;
	} else {
		return (0);
	}
	return (1);
}



/* record of offset between local time and PPS */
static void record(struct timespec t) 
{
  long d_sec, nsec;
  int hod,min,s, x_sec;
  d_sec = t.tv_sec % 86400L;
  hod = d_sec / 3600; x_sec = d_sec - hod * 3600;
  min = x_sec / 60; s = x_sec - min * 60;
  nsec = t.tv_nsec;
  if (nsec > 5e8) nsec -= 1e9;
  printf ("%2d:%02d:%02d %6ld  %09ld\n", hod,min,s, d_sec, nsec);
}

/* delays given time in [ns] */

delay_ns (long ns)
{
	struct timespec ns_delay;
	ns_delay.tv_sec = 0, ns_delay.tv_nsec = ns;
	nanosleep (&ns_delay,&ns_delay);
}

main ()
{
 int i;
	
 init(CLEAR_EDGE);

 while (1) {
  delay_ns (2e8);
  if (pps()) record (ts);
 }
}