akaros/tools/compilers/gcc-glibc/gcc-4.9.2-akaros/libgomp/config/akaros/wait.h
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   1/* Copyright (C) 2008, 2009, 2011 Free Software Foundation, Inc.
   2   Contributed by Jakub Jelinek <jakub@redhat.com>.
   3
   4   This file is part of the GNU OpenMP Library (libgomp).
   5
   6   Libgomp is free software; you can redistribute it and/or modify it
   7   under the terms of the GNU General Public License as published by
   8   the Free Software Foundation; either version 3, or (at your option)
   9   any later version.
  10
  11   Libgomp is distributed in the hope that it will be useful, but WITHOUT ANY
  12   WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
  13   FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  14   more details.
  15
  16   Under Section 7 of GPL version 3, you are granted additional
  17   permissions described in the GCC Runtime Library Exception, version
  18   3.1, as published by the Free Software Foundation.
  19
  20   You should have received a copy of the GNU General Public License and
  21   a copy of the GCC Runtime Library Exception along with this program;
  22   see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  23   <http://www.gnu.org/licenses/>.  */
  24
  25/* This is a Linux specific implementation of a mutex synchronization
  26   mechanism for libgomp.  This type is private to the library.  This
  27   implementation uses atomic instructions and the futex syscall.  */
  28
  29#ifndef GOMP_WAIT_H
  30#define GOMP_WAIT_H 1
  31
  32#include "libgomp.h"
  33#include <errno.h>
  34
  35#ifdef HAVE_ATTRIBUTE_VISIBILITY
  36# pragma GCC visibility push(hidden)
  37#endif
  38#include "libgomp_futex.h"
  39
  40static inline void do_wait (int *addr, int val)
  41{
  42  unsigned long long i, count = gomp_spin_count_var;
  43
  44  if (__builtin_expect (gomp_managed_threads > gomp_available_cpus, 0))
  45    count = gomp_throttled_spin_count_var;
  46  for (i = 0; i < count; i++)
  47    if (__builtin_expect (*addr != val, 0))
  48      return;
  49    else
  50      cpu_relax ();
  51  futex_wait (addr, val);
  52}
  53
  54#ifdef HAVE_ATTRIBUTE_VISIBILITY
  55# pragma GCC visibility pop
  56#endif
  57
  58#endif /* GOMP_WAIT_H */
  59