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) 35 static 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 42 #define TICK 10000 /* system clock resolution in microseconds */ 43 #define USPS 1000000 /* number of microseconds in a second */ 44 45 #define setvec(vec, a) \ 46 vec.sv_handler = a; vec.sv_mask = vec.sv_onstack = 0 47 48 static int ringring; 49 50 void 51 usleep(useconds) 52 unsigned int useconds; 53 { 54 register struct itimerval *itp; 55 struct itimerval itv, oitv; 56 struct sigvec vec, ovec; 57 long omask; 58 static void sleephandler(); 59 60 itp = &itv; 61 if (!useconds) 62 return; 63 timerclear(&itp->it_interval); 64 timerclear(&itp->it_value); 65 if (setitimer(ITIMER_REAL, itp, &oitv) < 0) 66 return; 67 itp->it_value.tv_sec = useconds / USPS; 68 itp->it_value.tv_usec = useconds % USPS; 69 if (timerisset(&oitv.it_value)) { 70 if (timercmp(&oitv.it_value, &itp->it_value, >)) { 71 oitv.it_value.tv_sec -= itp->it_value.tv_sec; 72 oitv.it_value.tv_usec -= itp->it_value.tv_usec; 73 if (oitv.it_value.tv_usec < 0) { 74 oitv.it_value.tv_usec += USPS; 75 oitv.it_value.tv_sec--; 76 } 77 } else { 78 itp->it_value = oitv.it_value; 79 oitv.it_value.tv_sec = 0; 80 oitv.it_value.tv_usec = 2 * TICK; 81 } 82 } 83 setvec(vec, sleephandler); 84 (void) sigvec(SIGALRM, &vec, &ovec); 85 omask = sigblock(sigmask(SIGALRM)); 86 ringring = 0; 87 (void) setitimer(ITIMER_REAL, itp, (struct itimerval *)0); 88 while (!ringring) 89 sigpause(omask &~ sigmask(SIGALRM)); 90 (void) sigvec(SIGALRM, &ovec, (struct sigvec *)0); 91 (void) sigsetmask(omask); 92 (void) setitimer(ITIMER_REAL, &oitv, (struct itimerval *)0); 93 } 94 95 static void 96 sleephandler() 97 { 98 ringring = 1; 99 } 100