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 the above copyright notice and this paragraph are
 * duplicated in all such forms and that any documentation,
 * advertising materials, and other materials related to such
 * distribution and use acknowledge that the software was developed
 * by the University of California, 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'' AND WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 */

#ifndef lint
static char sccsid[] = "@(#)hertz.c     5.3 (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);
}