/*-
 * Copyright (c) 2015 Taylor R. Campbell
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
 */

#ifndef	TIMER_H
#define	TIMER_H

#if 0

/* x86-specific rdtsc, not actually a cycle or nanosecond counter */

#include <stdint.h>

static uint64_t
rdtsc(void)
{
	uint32_t lo, hi;

	__asm__ __volatile__ ("rdtsc" : "=a"(lo), "=d"(hi));

	return ((uint64_t)hi << 32) | lo;
}

static inline unsigned long long
timer(void)
{

	return rdtsc();
}

#else

/* clock_gettime(CLOCK_MONOTONIC) nanosecond counter */

#include <err.h>
#include <time.h>

static inline unsigned long long
timer(void)
{
	struct timespec t;

	if (clock_gettime(CLOCK_MONOTONIC, &t) == -1)
		err(1, "clock_gettime");

	return 1000000000ULL*t.tv_sec + t.tv_nsec;
}

#endif

#endif	/* TIMER_H */