1/*	$NetBSD: clock.c,v 1.9.40.1 2008/11/08 21:45:38 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
35static char sccsid[] = "@(#)clock.c	8.1 (Berkeley) 6/4/93";
36#else
37__RCSID("$NetBSD: clock.c,v 1.9.40.1 2008/11/08 21:45:38 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
58clock_t
59clock(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