usr/src/usr.bin/gprof/hertz.c

/*
 * Copyright (c) 1983 Regents of the University of California.
 * All rights reserved.  The Berkeley software License Agreement
 * specifies the terms and conditions for redistribution.
 */

#ifndef lint
static char sccsid[] = "@(#)hertz.c     5.1 (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);
}