100 lines
3.4 KiB
C
100 lines
3.4 KiB
C
/*
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* Copyright (c) 1989, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#if defined(LIBC_SCCS) && !defined(lint)
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static char sccsid[] = "@(#)usleep.c 8.1 (Berkeley) 6/4/93";
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#endif /* LIBC_SCCS and not lint */
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#include <sys/time.h>
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#include <signal.h>
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#include <unistd.h>
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#define TICK 10000 /* system clock resolution in microseconds */
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#define USPS 1000000 /* number of microseconds in a second */
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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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void
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usleep(useconds)
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unsigned int useconds;
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{
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register struct itimerval *itp;
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struct itimerval itv, oitv;
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struct sigvec vec, ovec;
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long omask;
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static void sleephandler();
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itp = &itv;
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if (!useconds)
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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 = useconds / USPS;
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itp->it_value.tv_usec = useconds % 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, sleephandler);
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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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sleephandler()
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{
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ringring = 1;
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}
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