xref: /csrg-svn/lib/libc/gen/usleep.c (revision 61111)
122124Smckusick /*
2*61111Sbostic  * Copyright (c) 1989, 1993
3*61111Sbostic  *	The Regents of the University of California.  All rights reserved.
439170Sbostic  *
542628Sbostic  * %sccs.include.redist.c%
622124Smckusick  */
722124Smckusick 
826610Sdonn #if defined(LIBC_SCCS) && !defined(lint)
9*61111Sbostic static char sccsid[] = "@(#)usleep.c	8.1 (Berkeley) 06/04/93";
1039170Sbostic #endif /* LIBC_SCCS and not lint */
1118340Sserge 
1218340Sserge #include <sys/time.h>
1339170Sbostic #include <sys/signal.h>
1446597Sdonn #include <unistd.h>
1518340Sserge 
1639170Sbostic #define	TICK	10000		/* system clock resolution in microseconds */
1739170Sbostic #define	USPS	1000000		/* number of microseconds in a second */
1818340Sserge 
1918340Sserge #define	setvec(vec, a) \
2018340Sserge 	vec.sv_handler = a; vec.sv_mask = vec.sv_onstack = 0
2118340Sserge 
2218340Sserge static int ringring;
2318340Sserge 
2446597Sdonn void
usleep(useconds)2539170Sbostic usleep(useconds)
2639170Sbostic 	unsigned int useconds;
2718340Sserge {
2839170Sbostic 	register struct itimerval *itp;
2918340Sserge 	struct itimerval itv, oitv;
3018340Sserge 	struct sigvec vec, ovec;
3139170Sbostic 	long omask;
3246597Sdonn 	static void sleephandler();
3318340Sserge 
3439170Sbostic 	itp = &itv;
3539170Sbostic 	if (!useconds)
3618340Sserge 		return;
3718340Sserge 	timerclear(&itp->it_interval);
3818340Sserge 	timerclear(&itp->it_value);
3918340Sserge 	if (setitimer(ITIMER_REAL, itp, &oitv) < 0)
4018340Sserge 		return;
4139170Sbostic 	itp->it_value.tv_sec = useconds / USPS;
4239170Sbostic 	itp->it_value.tv_usec = useconds % USPS;
4318340Sserge 	if (timerisset(&oitv.it_value)) {
4418340Sserge 		if (timercmp(&oitv.it_value, &itp->it_value, >)) {
4518340Sserge 			oitv.it_value.tv_sec -= itp->it_value.tv_sec;
4618340Sserge 			oitv.it_value.tv_usec -= itp->it_value.tv_usec;
4718340Sserge 			if (oitv.it_value.tv_usec < 0) {
4818340Sserge 				oitv.it_value.tv_usec += USPS;
4918340Sserge 				oitv.it_value.tv_sec--;
5018340Sserge 			}
5118340Sserge 		} else {
5218340Sserge 			itp->it_value = oitv.it_value;
5318340Sserge 			oitv.it_value.tv_sec = 0;
5418340Sserge 			oitv.it_value.tv_usec = 2 * TICK;
5518340Sserge 		}
5618340Sserge 	}
5739170Sbostic 	setvec(vec, sleephandler);
5818340Sserge 	(void) sigvec(SIGALRM, &vec, &ovec);
5918340Sserge 	omask = sigblock(sigmask(SIGALRM));
6018340Sserge 	ringring = 0;
6118340Sserge 	(void) setitimer(ITIMER_REAL, itp, (struct itimerval *)0);
6218340Sserge 	while (!ringring)
6318340Sserge 		sigpause(omask &~ sigmask(SIGALRM));
6418340Sserge 	(void) sigvec(SIGALRM, &ovec, (struct sigvec *)0);
6518340Sserge 	(void) sigsetmask(omask);
6618340Sserge 	(void) setitimer(ITIMER_REAL, &oitv, (struct itimerval *)0);
6718340Sserge }
6818340Sserge 
6939170Sbostic static void
sleephandler()7039170Sbostic sleephandler()
7118340Sserge {
7218340Sserge 	ringring = 1;
7318340Sserge }
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