71 lines
1.7 KiB
C
71 lines
1.7 KiB
C
#if !defined(lint) && defined(SCCSIDS)
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static char sccsid[] = "@(#)usleep.c 1.1 92/07/30 SMI"; /* from UCB 5.1 85/06/05 */
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#endif
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/*
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* Copyright (c) 1985 Regents of the University of California.
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* All rights reserved. The Berkeley software License Agreement
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* specifies the terms and conditions for redistribution.
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*/
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#include <sys/time.h>
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#include <signal.h>
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#define USPS 1000000 /* number of microseconds in a second */
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#define TICK 10000 /* system clock resolution in microseconds */
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#define setvec(vec, a) \
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vec.sv_handler = a; vec.sv_mask = vec.sv_onstack = 0
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static int ringring;
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usleep(n)
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unsigned n;
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{
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static void sleepx();
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int omask;
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struct itimerval itv, oitv;
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register struct itimerval *itp = &itv;
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struct sigvec vec, ovec;
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if (n == 0)
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return;
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timerclear(&itp->it_interval);
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timerclear(&itp->it_value);
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if (setitimer(ITIMER_REAL, itp, &oitv) < 0)
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return;
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itp->it_value.tv_sec = n / USPS;
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itp->it_value.tv_usec = n % USPS;
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if (timerisset(&oitv.it_value)) {
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if (timercmp(&oitv.it_value, &itp->it_value, >)) {
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oitv.it_value.tv_sec -= itp->it_value.tv_sec;
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oitv.it_value.tv_usec -= itp->it_value.tv_usec;
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if (oitv.it_value.tv_usec < 0) {
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oitv.it_value.tv_usec += USPS;
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oitv.it_value.tv_sec--;
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}
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} else {
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itp->it_value = oitv.it_value;
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oitv.it_value.tv_sec = 0;
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oitv.it_value.tv_usec = 2 * TICK;
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}
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}
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setvec(vec, sleepx);
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(void) sigvec(SIGALRM, &vec, &ovec);
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omask = sigblock(sigmask(SIGALRM));
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ringring = 0;
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(void) setitimer(ITIMER_REAL, itp, (struct itimerval *)0);
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while (!ringring)
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sigpause(omask &~ sigmask(SIGALRM));
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(void) sigvec(SIGALRM, &ovec, (struct sigvec *)0);
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(void) sigsetmask(omask);
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(void) setitimer(ITIMER_REAL, &oitv, (struct itimerval *)0);
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}
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static void
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sleepx()
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{
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ringring = 1;
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}
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