11590Srgrimes/* 21590Srgrimes * Copyright (c) 1983, 1993 31590Srgrimes * The Regents of the University of California. All rights reserved. 41590Srgrimes * 51590Srgrimes * Redistribution and use in source and binary forms, with or without 61590Srgrimes * modification, are permitted provided that the following conditions 71590Srgrimes * are met: 81590Srgrimes * 1. Redistributions of source code must retain the above copyright 91590Srgrimes * notice, this list of conditions and the following disclaimer. 101590Srgrimes * 2. Redistributions in binary form must reproduce the above copyright 111590Srgrimes * notice, this list of conditions and the following disclaimer in the 121590Srgrimes * documentation and/or other materials provided with the distribution. 131590Srgrimes * 4. Neither the name of the University nor the names of its contributors 141590Srgrimes * may be used to endorse or promote products derived from this software 151590Srgrimes * without specific prior written permission. 161590Srgrimes * 171590Srgrimes * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 181590Srgrimes * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 191590Srgrimes * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 201590Srgrimes * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 211590Srgrimes * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 221590Srgrimes * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 231590Srgrimes * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 241590Srgrimes * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 251590Srgrimes * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 261590Srgrimes * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 271590Srgrimes * SUCH DAMAGE. 281590Srgrimes */ 291590Srgrimes 30105243Scharnier#if 0 311590Srgrimes#ifndef lint 321590Srgrimesstatic char sccsid[] = "@(#)hertz.c 8.1 (Berkeley) 6/6/93"; 331590Srgrimes#endif /* not lint */ 34105243Scharnier#endif 351590Srgrimes 36105243Scharnier#include <sys/cdefs.h> 37105243Scharnier__FBSDID("$FreeBSD$"); 38105243Scharnier 391590Srgrimes#include <sys/time.h> 401590Srgrimes 411590Srgrimes /* 421590Srgrimes * discover the tick frequency of the machine 431590Srgrimes * if something goes wrong, we return 0, an impossible hertz. 441590Srgrimes */ 451590Srgrimes#define HZ_WRONG 0 461590Srgrimes 47246783Scharnierint hertz(void); 48246783Scharnier 49136099Sstefanfint 50136099Sstefanfhertz(void) 511590Srgrimes{ 521590Srgrimes struct itimerval tim; 531590Srgrimes 541590Srgrimes tim.it_interval.tv_sec = 0; 551590Srgrimes tim.it_interval.tv_usec = 1; 561590Srgrimes tim.it_value.tv_sec = 0; 571590Srgrimes tim.it_value.tv_usec = 0; 581590Srgrimes setitimer(ITIMER_REAL, &tim, 0); 591590Srgrimes setitimer(ITIMER_REAL, 0, &tim); 601590Srgrimes if (tim.it_interval.tv_usec < 2) 611590Srgrimes return(HZ_WRONG); 621590Srgrimes return (1000000 / tim.it_interval.tv_usec); 631590Srgrimes} 64