sysdeps/i386/i686/hp-timing.h

   1 /* High precision, low overhead timing functions.  i686 version.
   2    Copyright (C) 1998-2017 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Ulrich Drepper <drepper@cygnus.com>, 1998.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, see
  18    <http://www.gnu.org/licenses/>.  */
  19
  20 #ifndef _HP_TIMING_H
  21 #define _HP_TIMING_H    1
  22
  23 /* We always assume having the timestamp register.  */
  24 #define HP_TIMING_AVAIL         (1)
  25 #define HP_SMALL_TIMING_AVAIL   (1)
  26
  27 /* We indeed have inlined functions.  */
  28 #define HP_TIMING_INLINE        (1)
  29
  30 /* We use 64bit values for the times.  */
  31 typedef unsigned long long int hp_timing_t;
  32
  33 /* That's quite simple.  Use the `rdtsc' instruction.  Note that the value
  34    might not be 100% accurate since there might be some more instructions
  35    running in this moment.  This could be changed by using a barrier like
  36    'cpuid' right before the `rdtsc' instruciton.  But we are not interested
  37    in accurate clock cycles here so we don't do this.  */
  38 #define HP_TIMING_NOW(Var)      __asm__ __volatile__ ("rdtsc" : "=A" (Var))
  39
  40 #include <hp-timing-common.h>
  41
  42 #endif  /* hp-timing.h */