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 are permitted 6 * provided that the above copyright notice and this paragraph are 7 * duplicated in all such forms and that any documentation, 8 * advertising materials, and other materials related to such 9 * distribution and use acknowledge that the software was developed 10 * by the University of California, Berkeley. The name of the 11 * University may not be used to endorse or promote products derived 12 * from this software without specific prior written permission. 13 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR 14 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED 15 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. 16 */ 17 18 #if defined(LIBC_SCCS) && !defined(lint) 19 static char sccsid[] = "@(#)usleep.c 5.4 (Berkeley) 09/18/89"; 20 #endif /* LIBC_SCCS and not lint */ 21 22 #include <sys/time.h> 23 #include <sys/signal.h> 24 25 #define TICK 10000 /* system clock resolution in microseconds */ 26 #define USPS 1000000 /* number of microseconds in a second */ 27 28 #define setvec(vec, a) \ 29 vec.sv_handler = a; vec.sv_mask = vec.sv_onstack = 0 30 31 static int ringring; 32 33 usleep(useconds) 34 unsigned int useconds; 35 { 36 register struct itimerval *itp; 37 struct itimerval itv, oitv; 38 struct sigvec vec, ovec; 39 long omask; 40 void sleephandler(); 41 42 itp = &itv; 43 if (!useconds) 44 return; 45 timerclear(&itp->it_interval); 46 timerclear(&itp->it_value); 47 if (setitimer(ITIMER_REAL, itp, &oitv) < 0) 48 return; 49 itp->it_value.tv_sec = useconds / USPS; 50 itp->it_value.tv_usec = useconds % USPS; 51 if (timerisset(&oitv.it_value)) { 52 if (timercmp(&oitv.it_value, &itp->it_value, >)) { 53 oitv.it_value.tv_sec -= itp->it_value.tv_sec; 54 oitv.it_value.tv_usec -= itp->it_value.tv_usec; 55 if (oitv.it_value.tv_usec < 0) { 56 oitv.it_value.tv_usec += USPS; 57 oitv.it_value.tv_sec--; 58 } 59 } else { 60 itp->it_value = oitv.it_value; 61 oitv.it_value.tv_sec = 0; 62 oitv.it_value.tv_usec = 2 * TICK; 63 } 64 } 65 setvec(vec, sleephandler); 66 (void) sigvec(SIGALRM, &vec, &ovec); 67 omask = sigblock(sigmask(SIGALRM)); 68 ringring = 0; 69 (void) setitimer(ITIMER_REAL, itp, (struct itimerval *)0); 70 while (!ringring) 71 sigpause(omask &~ sigmask(SIGALRM)); 72 (void) sigvec(SIGALRM, &ovec, (struct sigvec *)0); 73 (void) sigsetmask(omask); 74 (void) setitimer(ITIMER_REAL, &oitv, (struct itimerval *)0); 75 } 76 77 static void 78 sleephandler() 79 { 80 ringring = 1; 81 } 82