sysdeps/generic/prof-freq.c

   1 /* Return frequency of ticks reported by profil.  Generic version. */
   2 /*-
   3  * Copyright (c) 1983, 1992, 1993
   4  *      The Regents of the University of California.  All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  * 1. Redistributions of source code must retain the above copyright
  10  *    notice, this list of conditions and the following disclaimer.
  11  * 2. Redistributions in binary form must reproduce the above copyright
  12  *    notice, this list of conditions and the following disclaimer in the
  13  *    documentation and/or other materials provided with the distribution.
  14  * 3. All advertising materials mentioning features or use of this software
  15  *    must display the following acknowledgement:
  16  *      This product includes software developed by the University of
  17  *      California, Berkeley and its contributors.
  18  * 4. Neither the name of the University nor the names of its contributors
  19  *    may be used to endorse or promote products derived from this software
  20  *    without specific prior written permission.
  21  *
  22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  32  * SUCH DAMAGE.
  33  */
  34
  35
  36 #include <sys/types.h>
  37 #include <sys/time.h>
  38
  39 int
  40 __profile_frequency (void)
  41 {
  42   /*
  43    * Discover the tick frequency of the machine if something goes wrong,
  44    * we return 0, an impossible hertz.
  45    */
  46   struct itimerval tim;
  47
  48   tim.it_interval.tv_sec = 0;
  49   tim.it_interval.tv_usec = 1;
  50   tim.it_value.tv_sec = 0;
  51   tim.it_value.tv_usec = 0;
  52   __setitimer(ITIMER_REAL, &tim, 0);
  53   __setitimer(ITIMER_REAL, 0, &tim);
  54   if (tim.it_interval.tv_usec < 2)
  55     return 0;
  56   return (1000000 / tim.it_interval.tv_usec);
  57 }