gprof/hertz.c

   1 /*
   2  * Copyright (c) 1983 Regents of the University of California.
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms are permitted
   6  * provided that: (1) source distributions retain this entire copyright
   7  * notice and comment, and (2) distributions including binaries display
   8  * the following acknowledgement:  ``This product includes software
   9  * developed by the University of California, Berkeley and its contributors''
  10  * in the documentation or other materials provided with the distribution
  11  * and in all advertising materials mentioning features or use of this
  12  * software. Neither the name of the University nor the names of its
  13  * contributors may be used to endorse or promote products derived
  14  * from this software without specific prior written permission.
  15  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
  16  * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
  17  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  18  */
  19
  20 #ifndef lint
  21 static char sccsid[] = "@(#)hertz.c     5.4 (Berkeley) 6/1/90";
  22 #endif /* not lint */
  23
  24 #include <sys/time.h>
  25
  26     /*
  27      *  discover the tick frequency of the machine
  28      *  if something goes wrong, we return 0, an impossible hertz.
  29      */
  30 #define HZ_WRONG        0
  31
  32 #ifdef __MSDOS__
  33 #define HERTZ 18
  34 #endif
  35
  36 hertz()
  37 {
  38 #ifdef HERTZ
  39         return HERTZ;
  40 #else
  41         struct itimerval tim;
  42
  43         tim.it_interval.tv_sec = 0;
  44         tim.it_interval.tv_usec = 1;
  45         tim.it_value.tv_sec = 0;
  46         tim.it_value.tv_usec = 0;
  47         setitimer(ITIMER_REAL, &tim, 0);
  48         setitimer(ITIMER_REAL, 0, &tim);
  49         if (tim.it_interval.tv_usec < 2)
  50                 return(HZ_WRONG);
  51         return (1000000 / tim.it_interval.tv_usec);
  52 #endif
  53 }