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 }
74