minix/lib/libc/gen/clock.c

70 lines
2.7 KiB
C
Raw Normal View History

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