longclock.c

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/* $Id: longclock.c,v 1.13 2004/08/16 00:02:20 horms Exp $ */
/*
 * Longclock operations
 *
 * Copyright (c) 2002 International Business Machines
 * Author:	Alan Robertson <[e-mail]>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 * 
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 */

#include <portability.h>
#include <unistd.h>
#include <sys/times.h>
#include <clplumbing/longclock.h>

#ifndef CLOCK_T_IS_LONG_ENOUGH
static	unsigned long	lasttimes = 0L;
static	unsigned long	wrapcount = 0;
static	longclock_t	lc_wrapcount;
#endif

static	unsigned 	Hz = 0;
static	longclock_t 	Lc_Hz;
static	double		d_Hz;

#define	WRAPSHIFT	32

const longclock_t	zero_longclock = 0UL;

#ifndef CLOCK_T_IS_LONG_ENOUGH
#	undef time_longclock
#endif

#ifdef HAVE_LONGCLOCK_ARITHMETIC
#	undef	msto_longclock
#	undef	longclockto_ms
#	undef	secsto_longclock
#	undef	add_longclock
#	undef	sub_longclock
#	undef	cmp_longclock
#endif


unsigned
hz_longclock(void)
{
	if (Hz == 0) {
		/* Compute various hz-related constants */

		Hz = sysconf(_SC_CLK_TCK);
		Lc_Hz = Hz;
		d_Hz = (double) Hz;
	}
	return Hz;
}

#ifdef CLOCK_T_IS_LONG_ENOUGH

longclock_t
time_longclock(void)
{
	struct tms	longclock_dummy_tms_struct;
	return (longclock_t)times(&longclock_dummy_tms_struct);
}

#else	/* clock_t is shorter than 64 bits */

longclock_t
time_longclock(void)
{
	struct tms	longclock_dummy_tms_struct;
	unsigned long	timesval;
	
	
	/* times really returns an unsigned value ... */
	timesval = (unsigned long) times(&longclock_dummy_tms_struct);

	if (!lasttimes) {
		lasttimes = timesval;
	}


	if (timesval < lasttimes) {
		++wrapcount;
		lc_wrapcount = ((longclock_t)wrapcount) << WRAPSHIFT;
	}
	
	lasttimes = timesval;
	return (lc_wrapcount | (longclock_t)timesval);
}
#endif	/* ! CLOCK_T_IS_LONG_ENOUGH */

longclock_t
msto_longclock(unsigned long ms)
{
	unsigned long	secs =	ms / 1000UL;
	unsigned long	msec = ms % 1000;
	longclock_t	result;

	(void)(Hz == 0 && hz_longclock());

	if (ms == 0) {
		return (longclock_t)0UL;
	}
	result = secs * Lc_Hz + (msec * Lc_Hz)/1000;

	if (result == 0) {
		result = 1;
	}
	return result;
}

longclock_t
secsto_longclock(unsigned long Secs)
{
	longclock_t	secs = Secs;

	(void)(Hz == 0 && hz_longclock());

	return secs * Lc_Hz;
}

longclock_t
dsecsto_longclock(double v)
{
	(void)(Hz == 0 && hz_longclock());

	return (longclock_t) ((v * d_Hz)+0.5);
	
}

unsigned long
longclockto_ms(longclock_t t)
{
	(void)(Hz == 0 && hz_longclock());

	if (t == 0) {
		return 0UL;
	}
	return (unsigned long) ((t*1000UL)/Lc_Hz);
}
long
longclockto_long(longclock_t t)
{
	return	((long)(t));
}

longclock_t
add_longclock(longclock_t l, longclock_t r)
{
	return l + r;
}

longclock_t
sub_longclock(longclock_t l, longclock_t r)
{
	return l - r;
}

int
cmp_longclock(longclock_t l, longclock_t r)
{
	if (l < r) {
		return -1;
	}
	if (l > r) {
		return 1;
	}
	return 0;
}