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      1 /*	$NetBSD: clock.c,v 1.10 2009/01/11 02:46:27 christos Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 1989, 1993
      5  *	The Regents of the University of California.  All rights reserved.
      6  *
      7  * Redistribution and use in source and binary forms, with or without
      8  * modification, are permitted provided that the following conditions
      9  * are met:
     10  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  * 2. Redistributions in binary form must reproduce the above copyright
     13  *    notice, this list of conditions and the following disclaimer in the
     14  *    documentation and/or other materials provided with the distribution.
     15  * 3. Neither the name of the University nor the names of its contributors
     16  *    may be used to endorse or promote products derived from this software
     17  *    without specific prior written permission.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     29  * SUCH DAMAGE.
     30  */
     31 
     32 #include <sys/cdefs.h>
     33 #if defined(LIBC_SCCS) && !defined(lint)
     34 #if 0
     35 static char sccsid[] = "@(#)clock.c	8.1 (Berkeley) 6/4/93";
     36 #else
     37 __RCSID("$NetBSD: clock.c,v 1.10 2009/01/11 02:46:27 christos Exp $");
     38 #endif
     39 #endif /* LIBC_SCCS and not lint */
     40 
     41 #include <sys/param.h>
     42 #include <sys/time.h>
     43 #include <sys/resource.h>
     44 
     45 #include <time.h>
     46 
     47 /*
     48  * This code is all rather silly because the kernel counts actual
     49  * execution time (to usec accuracy) then splits it into user, system and
     50  * interrupt based on when clock ticks happen.  getrusage apportions the
     51  * time based on the number of ticks, and here we are trying to generate
     52  * a number which was, traditionally, the number of ticks!
     53  *
     54  * Due to the way the time is apportioned, this code (and indeed getrusage
     55  * itself) are not guaranteed monotonic.
     56  */
     57 
     58 clock_t
     59 clock(void)
     60 {
     61 	struct rusage ru;
     62 	clock_t hz = CLOCKS_PER_SEC;
     63 
     64 	if (getrusage(RUSAGE_SELF, &ru))
     65 		return ((clock_t) -1);
     66 	return (clock_t)((ru.ru_utime.tv_sec + ru.ru_stime.tv_sec) * hz +
     67 	    (ru.ru_utime.tv_usec + ru.ru_stime.tv_usec + 50)
     68 	    / 100 * hz / 10000);
     69 }
     70