usleep.c revision 18472
1/* 2 * Copyright (c) 1989, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 3. All advertising materials mentioning features or use of this software 14 * must display the following acknowledgement: 15 * This product includes software developed by the University of 16 * California, Berkeley and its contributors. 17 * 4. Neither the name of the University nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 */ 33 34#if defined(LIBC_SCCS) && !defined(lint) 35static char sccsid[] = "@(#)usleep.c 8.1 (Berkeley) 6/4/93"; 36#endif /* LIBC_SCCS and not lint */ 37 38#include <sys/time.h> 39#include <signal.h> 40#include <unistd.h> 41#ifdef _THREAD_SAFE 42#include <pthread.h> 43#include "pthread_private.h" 44#else 45#define TICK 10000 /* system clock resolution in microseconds */ 46#define USPS 1000000 /* number of microseconds in a second */ 47 48#define setvec(vec, a) \ 49 vec.sv_handler = a; vec.sv_mask = vec.sv_onstack = 0 50 51static int ringring; 52#endif 53 54 55void 56usleep(useconds) 57 unsigned int useconds; 58{ 59#ifdef _THREAD_SAFE 60 struct timespec time_to_sleep; 61 62 if (useconds) { 63 time_to_sleep.tv_nsec = (useconds % 1000000) * 1000; 64 time_to_sleep.tv_sec = useconds / 1000000; 65 nanosleep(&time_to_sleep,NULL); 66 } 67#else 68 register struct itimerval *itp; 69 struct itimerval itv, oitv; 70 struct sigvec vec, ovec; 71 long omask; 72 static void sleephandler(); 73 74 itp = &itv; 75 if (!useconds) 76 return; 77 timerclear(&itp->it_interval); 78 timerclear(&itp->it_value); 79 if (setitimer(ITIMER_REAL, itp, &oitv) < 0) 80 return; 81 itp->it_value.tv_sec = useconds / USPS; 82 itp->it_value.tv_usec = useconds % USPS; 83 if (timerisset(&oitv.it_value)) { 84 if (timercmp(&oitv.it_value, &itp->it_value, >)) { 85 oitv.it_value.tv_sec -= itp->it_value.tv_sec; 86 oitv.it_value.tv_usec -= itp->it_value.tv_usec; 87 if (oitv.it_value.tv_usec < 0) { 88 oitv.it_value.tv_usec += USPS; 89 oitv.it_value.tv_sec--; 90 } 91 } else { 92 itp->it_value = oitv.it_value; 93 oitv.it_value.tv_sec = 0; 94 oitv.it_value.tv_usec = 2 * TICK; 95 } 96 } 97 setvec(vec, sleephandler); 98 (void) sigvec(SIGALRM, &vec, &ovec); 99 omask = sigblock(sigmask(SIGALRM)); 100 ringring = 0; 101 (void) setitimer(ITIMER_REAL, itp, (struct itimerval *)0); 102 while (!ringring) 103 sigpause(omask &~ sigmask(SIGALRM)); 104 (void) sigvec(SIGALRM, &ovec, (struct sigvec *)0); 105 (void) sigsetmask(omask); 106 (void) setitimer(ITIMER_REAL, &oitv, (struct itimerval *)0); 107#endif 108} 109 110#ifndef _THREAD_SAFE 111static void 112sleephandler() 113{ 114 ringring = 1; 115} 116#endif 117