xref: /csrg-svn/lib/libc/gen/ualarm.c (revision 22123)
1*22123Smckusick /*
2*22123Smckusick  * Copyright (c) 1985 Regents of the University of California.
3*22123Smckusick  * All rights reserved.  The Berkeley software License Agreement
4*22123Smckusick  * specifies the terms and conditions for redistribution.
5*22123Smckusick  */
618339Sserge 
7*22123Smckusick #ifndef lint
8*22123Smckusick static char sccsid[] = "@(#)ualarm.c	5.1 (Berkeley) 06/05/85";
9*22123Smckusick #endif not lint
10*22123Smckusick 
1118339Sserge #include <sys/time.h>
1218339Sserge 
1318339Sserge #define	USPS	1000000		/* # of microseconds in a second */
1418339Sserge 
1518339Sserge /*
1618339Sserge  * Generate a SIGALRM signal in ``usecs'' microseconds.
1718339Sserge  * If ``reload'' is non-zero, keep generating SIGALRM
1818339Sserge  * every ``reload'' microseconds after the first signal.
1918339Sserge  */
2018339Sserge unsigned
2118339Sserge ualarm(usecs, reload)
2218339Sserge 	register unsigned usecs;
2318339Sserge 	register unsigned reload;
2418339Sserge {
2518339Sserge 	struct itimerval new, old;
2618339Sserge 
2718339Sserge 	new.it_interval.tv_usec = reload % USPS;
2818339Sserge 	new.it_interval.tv_sec = reload / USPS;
2918339Sserge 
3018339Sserge 	new.it_value.tv_usec = usecs % USPS;
3118339Sserge 	new.it_value.tv_sec = usecs / USPS;
3218339Sserge 
3318339Sserge 	if (setitimer(ITIMER_REAL, &new, &old) == 0)
3418339Sserge 		return (old.it_value.tv_sec * USPS + old.it_value.tv_usec);
3518339Sserge 	/* else */
3618339Sserge 		return (-1);
3718339Sserge }
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