1 /* 2 * Copyright (c) 1989, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * %sccs.include.redist.c% 6 */ 7 8 #if defined(LIBC_SCCS) && !defined(lint) 9 static char sccsid[] = "@(#)usleep.c 8.1 (Berkeley) 06/04/93"; 10 #endif /* LIBC_SCCS and not lint */ 11 12 #include <sys/time.h> 13 #include <sys/signal.h> 14 #include <unistd.h> 15 16 #define TICK 10000 /* system clock resolution in microseconds */ 17 #define USPS 1000000 /* number of microseconds in a second */ 18 19 #define setvec(vec, a) \ 20 vec.sv_handler = a; vec.sv_mask = vec.sv_onstack = 0 21 22 static int ringring; 23 24 void 25 usleep(useconds) 26 unsigned int useconds; 27 { 28 register struct itimerval *itp; 29 struct itimerval itv, oitv; 30 struct sigvec vec, ovec; 31 long omask; 32 static void sleephandler(); 33 34 itp = &itv; 35 if (!useconds) 36 return; 37 timerclear(&itp->it_interval); 38 timerclear(&itp->it_value); 39 if (setitimer(ITIMER_REAL, itp, &oitv) < 0) 40 return; 41 itp->it_value.tv_sec = useconds / USPS; 42 itp->it_value.tv_usec = useconds % USPS; 43 if (timerisset(&oitv.it_value)) { 44 if (timercmp(&oitv.it_value, &itp->it_value, >)) { 45 oitv.it_value.tv_sec -= itp->it_value.tv_sec; 46 oitv.it_value.tv_usec -= itp->it_value.tv_usec; 47 if (oitv.it_value.tv_usec < 0) { 48 oitv.it_value.tv_usec += USPS; 49 oitv.it_value.tv_sec--; 50 } 51 } else { 52 itp->it_value = oitv.it_value; 53 oitv.it_value.tv_sec = 0; 54 oitv.it_value.tv_usec = 2 * TICK; 55 } 56 } 57 setvec(vec, sleephandler); 58 (void) sigvec(SIGALRM, &vec, &ovec); 59 omask = sigblock(sigmask(SIGALRM)); 60 ringring = 0; 61 (void) setitimer(ITIMER_REAL, itp, (struct itimerval *)0); 62 while (!ringring) 63 sigpause(omask &~ sigmask(SIGALRM)); 64 (void) sigvec(SIGALRM, &ovec, (struct sigvec *)0); 65 (void) sigsetmask(omask); 66 (void) setitimer(ITIMER_REAL, &oitv, (struct itimerval *)0); 67 } 68 69 static void 70 sleephandler() 71 { 72 ringring = 1; 73 } 74