xref: /csrg-svn/lib/libc/gen/ualarm.c (revision 42627)
122123Smckusick /*
222123Smckusick  * Copyright (c) 1985 Regents of the University of California.
335306Sbostic  * All rights reserved.
435306Sbostic  *
5*42627Sbostic  * %sccs.include.redist.c%
622123Smckusick  */
718339Sserge 
826609Sdonn #if defined(LIBC_SCCS) && !defined(lint)
9*42627Sbostic static char sccsid[] = "@(#)ualarm.c	5.4 (Berkeley) 06/01/90";
1035306Sbostic #endif /* LIBC_SCCS and not lint */
1122123Smckusick 
1218339Sserge #include <sys/time.h>
1318339Sserge 
1418339Sserge #define	USPS	1000000		/* # of microseconds in a second */
1518339Sserge 
1618339Sserge /*
1718339Sserge  * Generate a SIGALRM signal in ``usecs'' microseconds.
1818339Sserge  * If ``reload'' is non-zero, keep generating SIGALRM
1918339Sserge  * every ``reload'' microseconds after the first signal.
2018339Sserge  */
2118339Sserge unsigned
2218339Sserge ualarm(usecs, reload)
2318339Sserge 	register unsigned usecs;
2418339Sserge 	register unsigned reload;
2518339Sserge {
2618339Sserge 	struct itimerval new, old;
2718339Sserge 
2818339Sserge 	new.it_interval.tv_usec = reload % USPS;
2918339Sserge 	new.it_interval.tv_sec = reload / USPS;
3018339Sserge 
3118339Sserge 	new.it_value.tv_usec = usecs % USPS;
3218339Sserge 	new.it_value.tv_sec = usecs / USPS;
3318339Sserge 
3418339Sserge 	if (setitimer(ITIMER_REAL, &new, &old) == 0)
3518339Sserge 		return (old.it_value.tv_sec * USPS + old.it_value.tv_usec);
3618339Sserge 	/* else */
3718339Sserge 		return (-1);
3818339Sserge }
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