sysdeps/generic/hp-timing.h

   1 /* High precision, low overhead timing functions.  Generic version.
   2    Copyright (C) 1998-2013 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
  24 /* There are no generic definitions for the times.  We could write something
  25    using the `gettimeofday' system call where available but the overhead of
  26    the system call might be too high.
  27
  28    In case a platform supports timers in the hardware the following macros
  29    and types must be defined:
  30
  31    - HP_TIMING_AVAIL: test for availability.
  32
  33    - HP_TIMING_INLINE: this macro is non-zero if the functionality is not
  34      implemented using function calls but instead uses some inlined code
  35      which might simply consist of a few assembler instructions.  We have to
  36      know this since we might want to use the macros here in places where we
  37      cannot make function calls.
  38
  39    - hp_timing_t: This is the type for variables used to store the time
  40      values.
  41
  42    - HP_TIMING_ZERO: clear `hp_timing_t' object.
  43
  44    - HP_TIMING_NOW: place timestamp for current time in variable given as
  45      parameter.
  46
  47    - HP_TIMING_DIFF_INIT: do whatever is necessary to be able to use the
  48      HP_TIMING_DIFF macro.
  49
  50    - HP_TIMING_DIFF: compute difference between two times and store it
  51      in a third.  Source and destination might overlap.
  52
  53    - HP_TIMING_ACCUM: add time difference to another variable.  This might
  54      be a bit more complicated to implement for some platforms as the
  55      operation should be thread-safe and 64bit arithmetic on 32bit platforms
  56      is not.
  57
  58    - HP_TIMING_ACCUM_NT: this is the variant for situations where we know
  59      there are no threads involved.
  60
  61    - HP_TIMING_PRINT: write decimal representation of the timing value into
  62      the given string.  This operation need not be inline even though
  63      HP_TIMING_INLINE is specified.
  64
  65 */
  66
  67 /* Provide dummy definitions.  */
  68 #define HP_TIMING_AVAIL         (0)
  69 #define HP_TIMING_INLINE        (0)
  70 typedef int hp_timing_t;
  71 #define HP_TIMING_ZERO(Var)
  72 #define HP_TIMING_NOW(var)
  73 #define HP_TIMING_DIFF_INIT()
  74 #define HP_TIMING_DIFF(Diff, Start, End)
  75 #define HP_TIMING_ACCUM(Sum, Diff)
  76 #define HP_TIMING_ACCUM_NT(Sum, Diff)
  77 #define HP_TIMING_PRINT(Buf, Len, Val)
  78
  79 /* Since this implementation is not available we tell the user about it.  */
  80 #define HP_TIMING_NONAVAIL      1
  81
  82 #endif  /* hp-timing.h */