1 /* 2 * Copyright (c) 1983, 1993, 2001 3 * The Regents of the University of California. All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 3. Neither the name of the University nor the names of its contributors 14 * may be used to endorse or promote products derived from this software 15 * without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 */ 29 #include "hertz.h" 30 31 32 int 33 hertz () 34 { 35 #ifdef HERTZ 36 return HERTZ; 37 #else /* ! defined (HERTZ) */ 38 #ifdef HAVE_SETITIMER 39 struct itimerval tim; 40 41 tim.it_interval.tv_sec = 0; 42 tim.it_interval.tv_usec = 1; 43 tim.it_value.tv_sec = 0; 44 tim.it_value.tv_usec = 0; 45 setitimer (ITIMER_REAL, &tim, 0); 46 setitimer (ITIMER_REAL, 0, &tim); 47 if (tim.it_interval.tv_usec >= 2) 48 { 49 return 1000000 / tim.it_interval.tv_usec; 50 } 51 #endif /* ! defined (HAVE_SETITIMER) */ 52 #if defined (HAVE_SYSCONF) && defined (_SC_CLK_TCK) 53 return sysconf (_SC_CLK_TCK); 54 #else /* ! defined (HAVE_SYSCONF) || ! defined (_SC_CLK_TCK) */ 55 #ifdef __MSDOS__ 56 return 18; 57 #else /* ! defined (__MSDOS__) */ 58 return HZ_WRONG; 59 #endif /* ! defined (__MSDOS__) */ 60 #endif /* ! defined (HAVE_SYSCONF) || ! defined (_SC_CLK_TCK) */ 61 #endif /* ! defined (HERTZ) */ 62 } 63