1/* 2 * Copyright (c) 1999 Apple Computer, Inc. All rights reserved. 3 * 4 * @APPLE_LICENSE_HEADER_START@ 5 * 6 * This file contains Original Code and/or Modifications of Original Code 7 * as defined in and that are subject to the Apple Public Source License 8 * Version 2.0 (the 'License'). You may not use this file except in 9 * compliance with the License. Please obtain a copy of the License at 10 * http://www.opensource.apple.com/apsl/ and read it before using this 11 * file. 12 * 13 * The Original Code and all software distributed under the License are 14 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER 15 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, 16 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, 17 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT. 18 * Please see the License for the specific language governing rights and 19 * limitations under the License. 20 * 21 * @APPLE_LICENSE_HEADER_END@ 22 */ 23/* $OpenBSD: hertz.c,v 1.2 1996/06/26 05:33:52 deraadt Exp $ */ 24/* $NetBSD: hertz.c,v 1.5 1995/04/19 07:16:03 cgd Exp $ */ 25 26/* 27 * Copyright (c) 1983, 1993 28 * The Regents of the University of California. All rights reserved. 29 * 30 * Redistribution and use in source and binary forms, with or without 31 * modification, are permitted provided that the following conditions 32 * are met: 33 * 1. Redistributions of source code must retain the above copyright 34 * notice, this list of conditions and the following disclaimer. 35 * 2. Redistributions in binary form must reproduce the above copyright 36 * notice, this list of conditions and the following disclaimer in the 37 * documentation and/or other materials provided with the distribution. 38 * 3. All advertising materials mentioning features or use of this software 39 * must display the following acknowledgement: 40 * This product includes software developed by the University of 41 * California, Berkeley and its contributors. 42 * 4. Neither the name of the University nor the names of its contributors 43 * may be used to endorse or promote products derived from this software 44 * without specific prior written permission. 45 * 46 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 47 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 48 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 49 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 50 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 51 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 52 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 53 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 54 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 55 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 56 * SUCH DAMAGE. 57 */ 58#include <stdint.h> 59#include <sys/time.h> 60 61 /* 62 * discover the tick frequency of the machine 63 * if something goes wrong, we return 0, an impossible hertz. 64 */ 65#define HZ_WRONG 0 66 67uint32_t 68hertz( 69void) 70{ 71 struct itimerval tim; 72 73 tim.it_interval.tv_sec = 0; 74 tim.it_interval.tv_usec = 1; 75 tim.it_value.tv_sec = 0; 76 tim.it_value.tv_usec = 0; 77 setitimer(ITIMER_REAL, &tim, 0); 78 setitimer(ITIMER_REAL, 0, &tim); 79 if (tim.it_interval.tv_usec < 2) 80 return(HZ_WRONG); 81 return (1000000 / tim.it_interval.tv_usec); 82} 83