sysdeps/unix/bsd/ualarm.c

   1 /* Copyright (C) 1991 Free Software Foundation, Inc.
   2 This file is part of the GNU C Library.
   3
   4 The GNU C Library is free software; you can redistribute it and/or
   5 modify it under the terms of the GNU Library General Public License as
   6 published by the Free Software Foundation; either version 2 of the
   7 License, or (at your option) any later version.
   8
   9 The GNU C Library is distributed in the hope that it will be useful,
  10 but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12 Library General Public License for more details.
  13
  14 You should have received a copy of the GNU Library General Public
  15 License along with the GNU C Library; see the file COPYING.LIB.  If
  16 not, write to the Free Software Foundation, Inc., 675 Mass Ave,
  17 Cambridge, MA 02139, USA.  */
  18
  19 #include <ansidecl.h>
  20 #include <sys/time.h>
  21
  22 /* Set an alarm to go off (generating a SIGALRM signal) in VALUE microseconds.
  23    If INTERVAL is nonzero, when the alarm goes off, the timer is reset to go
  24    off every INTERVAL microseconds thereafter.
  25
  26    Returns the number of microseconds remaining before the alarm.  */
  27 unsigned int
  28 DEFUN(ualarm, (value, interval),
  29       unsigned int value AND unsigned int interval)
  30 {
  31   struct itimerval timer, otimer;
  32
  33   timer.it_value.tv_sec = 0;
  34   timer.it_value.tv_usec = value;
  35   timer.it_interval.tv_sec = 0;
  36   timer.it_interval.tv_usec = interval;
  37
  38   if (setitimer(ITIMER_REAL, &timer, &otimer) < 0)
  39     return -1;
  40
  41   return (otimer.it_value.tv_sec * 1000000) + otimer.it_value.tv_usec;
  42 }