/*	spin.c
	Equivalent to "sleep" except that resolution is milliseconds instead
	of seconds.
	Written by David Horton	6-Jan-92
	Bugs:
		This consumes CPU resource
*/

#include <stdio.h>
#ifndef _INCLUDE_POSIX_SOURCE
#define _INCLUDE_POSIX_SOURCE
#endif
#ifndef _INCLUDE_HPUX_SOURCE
#define _INCLUDE_HPUX_SOURCE
#endif
#include <time.h>
#include <errno.h>

main (int argc, char *argv[]) {
	int		milli;					/* milli seconds to spin for */
	int		secs;					/* milli seconds part > 1000 */
	struct timeval	now;			/* time at the present moment */
	struct timeval	then;			/* when our time expires */
	struct timezone	us;				/* unused */

	if (argc != 2) {
		fprintf(stderr,"Usage: %s milliseconds\n", argv[0]);
		exit (1);
	}

	milli = atoi(argv[1]);			/* see how long to sleep */
	secs = milli / 1000;			/* split into parts for structure */
	milli = milli % 1000;
	if (gettimeofday(&now, &us)){	/* when is that in the future */
		perror("gettimeofday");
		exit (errno);
	}
	then.tv_usec = now.tv_usec + milli * 1000;	/*we'll fix the wrap next*/
	then.tv_sec = now.tv_sec + secs + then.tv_usec / 1000000;
	then.tv_usec = then.tv_usec % 1000000;

#	ifdef DEBUG
	printf("now %d.%6d, then %d.%6d\n", 
		now.tv_sec, now.tv_usec, then.tv_sec, then.tv_usec);
#	endif

	while (timercmp(&now, &then, <)) {	/* is the time up yet ? -> busy wait */
		if (gettimeofday(&now, &us)){	/* when is that in the future */
			perror("gettimeofday");
			exit (errno);
		}
	}
#	ifdef DEBUG
	printf("now %d.%6d, then %d.%6d\n", 
		now.tv_sec, now.tv_usec, then.tv_sec, then.tv_usec);
#	endif

	exit(0);
}