4.3BSD - /usr/src/lib/libc/gen/usleep.c

   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	5.2 (Berkeley) 3/9/86";
   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(), omask;
  26:     struct itimerval itv, oitv;
  27:     register struct itimerval *itp = &itv;
  28:     struct sigvec vec, ovec;
  29: 
  30:     if (n == 0)
  31:         return;
  32:     timerclear(&itp->it_interval);
  33:     timerclear(&itp->it_value);
  34:     if (setitimer(ITIMER_REAL, itp, &oitv) < 0)
  35:         return;
  36:     itp->it_value.tv_sec = n / USPS;
  37:     itp->it_value.tv_usec = n % USPS;
  38:     if (timerisset(&oitv.it_value)) {
  39:         if (timercmp(&oitv.it_value, &itp->it_value, >)) {
  40:             oitv.it_value.tv_sec -= itp->it_value.tv_sec;
  41:             oitv.it_value.tv_usec -= itp->it_value.tv_usec;
  42:             if (oitv.it_value.tv_usec < 0) {
  43:                 oitv.it_value.tv_usec += USPS;
  44:                 oitv.it_value.tv_sec--;
  45:             }
  46:         } else {
  47:             itp->it_value = oitv.it_value;
  48:             oitv.it_value.tv_sec = 0;
  49:             oitv.it_value.tv_usec = 2 * TICK;
  50:         }
  51:     }
  52:     setvec(vec, sleepx);
  53:     (void) sigvec(SIGALRM, &vec, &ovec);
  54:     omask = sigblock(sigmask(SIGALRM));
  55:     ringring = 0;
  56:     (void) setitimer(ITIMER_REAL, itp, (struct itimerval *)0);
  57:     while (!ringring)
  58:         sigpause(omask &~ sigmask(SIGALRM));
  59:     (void) sigvec(SIGALRM, &ovec, (struct sigvec *)0);
  60:     (void) sigsetmask(omask);
  61:     (void) setitimer(ITIMER_REAL, &oitv, (struct itimerval *)0);
  62: }
  63: 
  64: static
  65: sleepx()
  66: {
  67: 
  68:     ringring = 1;
  69: }

Defined functions

Defined variables

Defined macros