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glibc  2.9
prof-freq.c
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00001 /* Return frequency of ticks reported by profil.  Generic version. */
00002 /*-
00003  * Copyright (c) 1983, 1992, 1993
00004  *     The Regents of the University of California.  All rights reserved.
00005  *
00006  * Redistribution and use in source and binary forms, with or without
00007  * modification, are permitted provided that the following conditions
00008  * are met:
00009  * 1. Redistributions of source code must retain the above copyright
00010  *    notice, this list of conditions and the following disclaimer.
00011  * 2. Redistributions in binary form must reproduce the above copyright
00012  *    notice, this list of conditions and the following disclaimer in the
00013  *    documentation and/or other materials provided with the distribution.
00014  * 4. Neither the name of the University nor the names of its contributors
00015  *    may be used to endorse or promote products derived from this software
00016  *    without specific prior written permission.
00017  *
00018  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
00019  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
00020  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
00021  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
00022  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
00023  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
00024  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
00025  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
00026  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
00027  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
00028  * SUCH DAMAGE.
00029  */
00030 
00031 
00032 #include <sys/types.h>
00033 #include <sys/time.h>
00034 #include <libc-internal.h>
00035 
00036 int
00037 __profile_frequency (void)
00038 {
00039   /*
00040    * Discover the tick frequency of the machine if something goes wrong,
00041    * we return 0, an impossible hertz.
00042    */
00043   struct itimerval tim;
00044 
00045   tim.it_interval.tv_sec = 0;
00046   tim.it_interval.tv_usec = 1;
00047   tim.it_value.tv_sec = 0;
00048   tim.it_value.tv_usec = 0;
00049   __setitimer(ITIMER_REAL, &tim, 0);
00050   __setitimer(ITIMER_REAL, 0, &tim);
00051   if (tim.it_interval.tv_usec < 2)
00052     return 0;
00053   return (1000000 / tim.it_interval.tv_usec);
00054 }
00055 libc_hidden_def (__profile_frequency)