lib/libc/gen/ualarm.c

   1 /*
   2  * Copyright (c) 1985, 1993
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. Neither the name of the University nor the names of its contributors
  14  *    may be used to endorse or promote products derived from this software
  15  *    without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  *
  29  * @(#)ualarm.c 8.1 (Berkeley) 6/4/93
  30  */
  31
  32 #include <sys/time.h>
  33 #include <unistd.h>
  34
  35 #define USPS    1000000         /* # of microseconds in a second */
  36
  37 /*
  38  * Generate a SIGALRM signal in ``usecs'' microseconds.
  39  * If ``reload'' is non-zero, keep generating SIGALRM
  40  * every ``reload'' microseconds after the first signal.
  41  */
  42 unsigned
  43 ualarm(unsigned usecs, unsigned reload)
  44 {
  45         struct itimerval new, old;
  46
  47         new.it_interval.tv_usec = reload % USPS;
  48         new.it_interval.tv_sec = reload / USPS;
  49
  50         new.it_value.tv_usec = usecs % USPS;
  51         new.it_value.tv_sec = usecs / USPS;
  52
  53         if (setitimer(ITIMER_REAL, &new, &old) == 0)
  54                 return (old.it_value.tv_sec * USPS + old.it_value.tv_usec);
  55
  56         return (-1);
  57 }