| 1 | /* |
| 2 | * Copyright (c) 1989 The Regents of the University of California. |
| 3 | * All rights reserved. |
| 4 | * |
| 5 | * %sccs.include.redist.c% |
| 6 | */ |
| 7 | |
| 8 | #if defined(LIBC_SCCS) && !defined(lint) |
| 9 | static char sccsid[] = "@(#)usleep.c 5.5 (Berkeley) %G%"; |
| 10 | #endif /* LIBC_SCCS and not lint */ |
| 11 | |
| 12 | #include <sys/time.h> |
| 13 | #include <sys/signal.h> |
| 14 | |
| 15 | #define TICK 10000 /* system clock resolution in microseconds */ |
| 16 | #define USPS 1000000 /* number of microseconds in a second */ |
| 17 | |
| 18 | #define setvec(vec, a) \ |
| 19 | vec.sv_handler = a; vec.sv_mask = vec.sv_onstack = 0 |
| 20 | |
| 21 | static int ringring; |
| 22 | |
| 23 | usleep(useconds) |
| 24 | unsigned int useconds; |
| 25 | { |
| 26 | register struct itimerval *itp; |
| 27 | struct itimerval itv, oitv; |
| 28 | struct sigvec vec, ovec; |
| 29 | long omask; |
| 30 | void sleephandler(); |
| 31 | |
| 32 | itp = &itv; |
| 33 | if (!useconds) |
| 34 | return; |
| 35 | timerclear(&itp->it_interval); |
| 36 | timerclear(&itp->it_value); |
| 37 | if (setitimer(ITIMER_REAL, itp, &oitv) < 0) |
| 38 | return; |
| 39 | itp->it_value.tv_sec = useconds / USPS; |
| 40 | itp->it_value.tv_usec = useconds % USPS; |
| 41 | if (timerisset(&oitv.it_value)) { |
| 42 | if (timercmp(&oitv.it_value, &itp->it_value, >)) { |
| 43 | oitv.it_value.tv_sec -= itp->it_value.tv_sec; |
| 44 | oitv.it_value.tv_usec -= itp->it_value.tv_usec; |
| 45 | if (oitv.it_value.tv_usec < 0) { |
| 46 | oitv.it_value.tv_usec += USPS; |
| 47 | oitv.it_value.tv_sec--; |
| 48 | } |
| 49 | } else { |
| 50 | itp->it_value = oitv.it_value; |
| 51 | oitv.it_value.tv_sec = 0; |
| 52 | oitv.it_value.tv_usec = 2 * TICK; |
| 53 | } |
| 54 | } |
| 55 | setvec(vec, sleephandler); |
| 56 | (void) sigvec(SIGALRM, &vec, &ovec); |
| 57 | omask = sigblock(sigmask(SIGALRM)); |
| 58 | ringring = 0; |
| 59 | (void) setitimer(ITIMER_REAL, itp, (struct itimerval *)0); |
| 60 | while (!ringring) |
| 61 | sigpause(omask &~ sigmask(SIGALRM)); |
| 62 | (void) sigvec(SIGALRM, &ovec, (struct sigvec *)0); |
| 63 | (void) sigsetmask(omask); |
| 64 | (void) setitimer(ITIMER_REAL, &oitv, (struct itimerval *)0); |
| 65 | } |
| 66 | |
| 67 | static void |
| 68 | sleephandler() |
| 69 | { |
| 70 | ringring = 1; |
| 71 | } |