glibc/sysdeps/i386/i686/hp-timing.h
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C

/* High precision, low overhead timing functions. i686 version.
Copyright (C) 1998-2018 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Ulrich Drepper <drepper@cygnus.com>, 1998.
The GNU C 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.
The GNU C 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 the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#ifndef _HP_TIMING_H
#define _HP_TIMING_H 1
/* We always assume having the timestamp register. */
#define HP_TIMING_AVAIL (1)
#define HP_SMALL_TIMING_AVAIL (1)
/* We indeed have inlined functions. */
#define HP_TIMING_INLINE (1)
/* We use 64bit values for the times. */
typedef unsigned long long int hp_timing_t;
/* That's quite simple. Use the `rdtsc' instruction. Note that the value
might not be 100% accurate since there might be some more instructions
running in this moment. This could be changed by using a barrier like
'cpuid' right before the `rdtsc' instruciton. But we are not interested
in accurate clock cycles here so we don't do this. */
#define HP_TIMING_NOW(Var) __asm__ __volatile__ ("rdtsc" : "=A" (Var))
#include <hp-timing-common.h>
#endif /* hp-timing.h */