1 /* 2 * Copyright (c) 1989 The Regents of the University of California. 3 * 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) 35 /*static char sccsid[] = "from: @(#)usleep.c 5.6 (Berkeley) 2/23/91";*/ 36 static char rcsid[] = "$Id: usleep.c,v 1.2 1993/07/30 08:23:58 mycroft Exp $"; 37 #endif /* LIBC_SCCS and not lint */ 38 39 #include <sys/time.h> 40 #include <sys/signal.h> 41 #include <unistd.h> 42 43 #define TICK 10000 /* system clock resolution in microseconds */ 44 #define USPS 1000000 /* number of microseconds in a second */ 45 46 #define setvec(vec, a) \ 47 vec.sv_handler = a; vec.sv_mask = vec.sv_onstack = 0 48 49 static int ringring; 50 51 void 52 usleep(useconds) 53 unsigned int useconds; 54 { 55 register struct itimerval *itp; 56 struct itimerval itv, oitv; 57 struct sigvec vec, ovec; 58 long omask; 59 static void sleephandler(); 60 61 itp = &itv; 62 if (!useconds) 63 return; 64 timerclear(&itp->it_interval); 65 timerclear(&itp->it_value); 66 if (setitimer(ITIMER_REAL, itp, &oitv) < 0) 67 return; 68 itp->it_value.tv_sec = useconds / USPS; 69 itp->it_value.tv_usec = useconds % USPS; 70 if (timerisset(&oitv.it_value)) { 71 if (timercmp(&oitv.it_value, &itp->it_value, >)) { 72 oitv.it_value.tv_sec -= itp->it_value.tv_sec; 73 oitv.it_value.tv_usec -= itp->it_value.tv_usec; 74 if (oitv.it_value.tv_usec < 0) { 75 oitv.it_value.tv_usec += USPS; 76 oitv.it_value.tv_sec--; 77 } 78 } else { 79 itp->it_value = oitv.it_value; 80 oitv.it_value.tv_sec = 0; 81 oitv.it_value.tv_usec = 2 * TICK; 82 } 83 } 84 setvec(vec, sleephandler); 85 (void) sigvec(SIGALRM, &vec, &ovec); 86 omask = sigblock(sigmask(SIGALRM)); 87 ringring = 0; 88 (void) setitimer(ITIMER_REAL, itp, (struct itimerval *)0); 89 while (!ringring) 90 sigpause(omask &~ sigmask(SIGALRM)); 91 (void) sigvec(SIGALRM, &ovec, (struct sigvec *)0); 92 (void) sigsetmask(omask); 93 (void) setitimer(ITIMER_REAL, &oitv, (struct itimerval *)0); 94 } 95 96 static void 97 sleephandler() 98 { 99 ringring = 1; 100 } 101