4.3BSD-UWisc/src/lib/libc/gen/ualarm.c

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#if defined(LIBC_RCS) && !defined(lint)
static char rcs_id[] =
	"$Header: ualarm.c,v 1.3 86/09/08 14:45:55 tadl Exp $";
#endif
/*
 * RCS info
 *	$Locker:  $
 */
/*
 * Copyright (c) 1985 Regents of the University of California.
 * All rights reserved.  The Berkeley software License Agreement
 * specifies the terms and conditions for redistribution.
 */

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)ualarm.c	5.2 (Berkeley) 3/9/86";
#endif LIBC_SCCS and not lint

#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);
}