ualarm.c

操作系统SunOS 4.1.3版本的源码

#if !defined(lint) && defined(SCCSIDS)
static	char sccsid[] = "@(#)ualarm.c 1.1 92/07/30 SMI"; /* from UCB 5.1 85/06/05 */
#endif

/*
 * Copyright (c) 1985 Regents of the University of California.
 * All rights reserved.  The Berkeley software License Agreement
 * specifies the terms and conditions for redistribution.
 */

#include <sys/time.h>

#define	USPS	1000000		/* # of microseconds in a second */

/*
 * Generate a SIGALRM signal in ``usecs'' microseconds.
 * If ``reload'' is non-zero, keep generating SIGALRM
 * every ``reload'' microseconds after the first signal.
 */
unsigned
ualarm(usecs, reload)
	register unsigned usecs;
	register unsigned reload;
{
	struct itimerval new, old;

	new.it_interval.tv_usec = reload % USPS;
	new.it_interval.tv_sec = reload / USPS;
	
	new.it_value.tv_usec = usecs % USPS;
	new.it_value.tv_sec = usecs / USPS;

	if (setitimer(ITIMER_REAL, &new, &old) == 0)
		return (old.it_value.tv_sec * USPS + old.it_value.tv_usec);
	/* else */
		return (-1);
}