sysdeps/powerpc/powerpc32/power4/hp-timing.h

   1 /* High precision, low overhead timing functions.  powerpc64 version.
   2    Copyright (C) 2005-2020 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    <https://www.gnu.org/licenses/>.  */
  19
  20 #ifndef _HP_TIMING_H
  21 #define _HP_TIMING_H    1
  22
  23 /* We indeed have inlined functions.  */
  24 #define HP_TIMING_INLINE        (1)
  25
  26 /* We use 64bit values for the times.  */
  27 typedef unsigned long long int hp_timing_t;
  28
  29 /* That's quite simple.  Use the `mftb' instruction.  Note that the value
  30    might not be 100% accurate since there might be some more instructions
  31    running in this moment.  This could be changed by using a barrier like
  32    'lwsync' right before the `mftb' instruction.  But we are not interested
  33    in accurate clock cycles here so we don't do this.  */
  34
  35 #define HP_TIMING_NOW(Var)                                              \
  36   do {                                                                  \
  37     unsigned int hi, lo, tmp;                                           \
  38     __asm__ __volatile__ ("1:   mfspr   %0,269;"                        \
  39                           "     mfspr   %1,268;"                        \
  40                           "     mfspr   %2,269;"                        \
  41                           "     cmpw    %0,%2;"                         \
  42                           "     bne     1b;"                            \
  43                           : "=&r" (hi), "=&r" (lo), "=&r" (tmp)         \
  44                           : : "cr0");                                   \
  45     Var = ((hp_timing_t) hi << 32) | lo;                                \
  46   } while (0)
  47
  48 #include <hp-timing-common.h>
  49
  50 #endif  /* hp-timing.h */