add Berkeley specific header; written by K. McKusick and P. Kessler

[unix-history] / usr / src / usr.bin / gprof / hertz.c

/*
* Copyright (c) 1983 Regents of the University of California.
* All rights reserved.
*
* Redistribution and use in source and binary forms are permitted
* provided that this notice is preserved and that due credit is given
* to the University of California at Berkeley. The name of the University
* may not be used to endorse or promote products derived from this
* software without specific prior written permission. This software
* is provided ``as is'' without express or implied warranty.
*/

#ifndef lint
static char sccsid[] = "@(#)hertz.c     5.2 (Berkeley) %G%";
#endif /* not lint */

#include <sys/time.h>

   /*
    *  discover the tick frequency of the machine
    *  if something goes wrong, we return 0, an impossible hertz.
    */
#define HZ_WRONG        0

hertz()
{
       struct itimerval tim;

       tim.it_interval.tv_sec = 0;
       tim.it_interval.tv_usec = 1;
       tim.it_value.tv_sec = 0;
       tim.it_value.tv_usec = 0;
       setitimer(ITIMER_REAL, &tim, 0);
       setitimer(ITIMER_REAL, 0, &tim);
       if (tim.it_interval.tv_usec < 2)
               return(HZ_WRONG);
       return (1000000 / tim.it_interval.tv_usec);
}