1 /* 2 * Copyright (c) 1985 Regents of the University of California. 3 * All rights reserved. The Berkeley software License Agreement 4 * specifies the terms and conditions for redistribution. 5 */ 6 7 #if defined(LIBC_SCCS) && !defined(lint) 8 static char sccsid[] = "@(#)usleep.c 5.3 (Berkeley) 09/30/87"; 9 #endif LIBC_SCCS and not lint 10 11 #include <sys/time.h> 12 #include <signal.h> 13 14 #define USPS 1000000 /* number of microseconds in a second */ 15 #define TICK 10000 /* system clock resolution in microseconds */ 16 17 #define setvec(vec, a) \ 18 vec.sv_handler = a; vec.sv_mask = vec.sv_onstack = 0 19 20 static int ringring; 21 22 usleep(n) 23 unsigned n; 24 { 25 int sleepx(); 26 long omask; 27 struct itimerval itv, oitv; 28 register struct itimerval *itp = &itv; 29 struct sigvec vec, ovec; 30 31 if (n == 0) 32 return; 33 timerclear(&itp->it_interval); 34 timerclear(&itp->it_value); 35 if (setitimer(ITIMER_REAL, itp, &oitv) < 0) 36 return; 37 itp->it_value.tv_sec = n / USPS; 38 itp->it_value.tv_usec = n % USPS; 39 if (timerisset(&oitv.it_value)) { 40 if (timercmp(&oitv.it_value, &itp->it_value, >)) { 41 oitv.it_value.tv_sec -= itp->it_value.tv_sec; 42 oitv.it_value.tv_usec -= itp->it_value.tv_usec; 43 if (oitv.it_value.tv_usec < 0) { 44 oitv.it_value.tv_usec += USPS; 45 oitv.it_value.tv_sec--; 46 } 47 } else { 48 itp->it_value = oitv.it_value; 49 oitv.it_value.tv_sec = 0; 50 oitv.it_value.tv_usec = 2 * TICK; 51 } 52 } 53 setvec(vec, sleepx); 54 (void) sigvec(SIGALRM, &vec, &ovec); 55 omask = sigblock(sigmask(SIGALRM)); 56 ringring = 0; 57 (void) setitimer(ITIMER_REAL, itp, (struct itimerval *)0); 58 while (!ringring) 59 sigpause(omask &~ sigmask(SIGALRM)); 60 (void) sigvec(SIGALRM, &ovec, (struct sigvec *)0); 61 (void) sigsetmask(omask); 62 (void) setitimer(ITIMER_REAL, &oitv, (struct itimerval *)0); 63 } 64 65 static 66 sleepx() 67 { 68 69 ringring = 1; 70 } 71