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/* timing.c -- cross-platform wall time
* Copyright (C) 2013 Galois, Inc. All rights reserved. */
#ifdef HAVE_CONFIG_H
# include <config.h>
#endif
#define _POSIX_C_SOURCE 199309L
#include <stdint.h>
#include "timing.h"
#include "require.h"
#define ignore(var) ((void)(var))
const uint64_t MICRO_PER_BASE = 1000000;
const uint64_t NANO_PER_MICRO = 1000;
// Try to use the POSIX timers, if possible.
#if HAVE_UNISTD_H
# include <unistd.h>
#endif
#if (HAVE_UNISTD_H && _POSIX_TIMERS > 0)
# include <time.h>
# if __linux__
/* Hopefully, you're running linux >=2.6.28, and
* CLOCK_MONOTONIC_RAW exists. */
static const clockid_t CLOCK_ID = CLOCK_MONOTONIC_RAW;
# elif _POSIX_MONOTONIC_CLOCK
// You're not on Linux, but you've got a POSIX monotonic clock.
static const clockid_t CLOCK_ID = CLOCK_MONOTONIC;
# else
// Just use the POSIX wall clock.
static const clockid_t CLOCK_ID = CLOCK_REALTIME;
# endif
int timing_get_wall(uint64_t *const result)
{
int r = 0;
struct timespec now;
require_zero(clock_gettime(CLOCK_ID, &now), 1);
*result = (uint64_t)now.tv_sec * MICRO_PER_BASE
+ (uint64_t)now.tv_nsec / NANO_PER_MICRO;
done: return r;
}
#elif (__APPLE__ && __MACH__)
/* No POSIX timers, but we're on a Mac, so we can use
* 'mach_absolute_time'. */
# include <mach/mach_time.h>
int timing_get_wall(uint64_t *const result)
{
static mach_timebase_info_data_t timebase_info;
int r = 0;
*result = mach_absolute_time();
/* *result is now in units of Mach ticks. Convert that to
* nanoseconds using the timebase information that Mach
* provides. Note that 'timebase_info' is static, so it got
* zeroed out at the start of the program run; if its
* denominator is still zero, we've definitely not stored
* anything in it yet. */
if (timebase_info.denom == 0) {
require_zero(mach_timebase_info(&timebase_info), 1);
}
*result = *result * timebase_info.numer / timebase_info.denom;
// Convert nanoseconds to microseconds.
*result /= NANO_PER_MICRO;
done: return r;
}
#else
// I have no clue what wacky platform you're on.
# error Unsupported timing platform
int timing_get_wall(uint64_t *const result)
{
ignore(result);
return -1;
}
#endif
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