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/* Copyright (C) 2005, 2009 Free Software Foundation, Inc.

   Contributed by Richard Henderson <rth@redhat.com>.

   This file is part of the GNU OpenMP Library (libgomp).

   Libgomp is free software; you can redistribute it and/or modify it

   under the terms of the GNU General Public License as published by

   the Free Software Foundation; either version 3, or (at your option)

   any later version.

   Libgomp 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 General Public License for

   more details.

   Under Section 7 of GPL version 3, you are granted additional

   permissions described in the GCC Runtime Library Exception, version

   3.1, as published by the Free Software Foundation.

   You should have received a copy of the GNU General Public License and

   a copy of the GCC Runtime Library Exception along with this program;

   see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see

   <http://www.gnu.org/licenses/>.  */

/* This is a Linux specific implementation of a mutex synchronization

   mechanism for libgomp.  This type is private to the library.  This

   implementation uses atomic instructions and the futex syscall.  */

#ifndef GOMP_MUTEX_H

#define GOMP_MUTEX_H 1

typedef int gomp_mutex_t;

#define GOMP_MUTEX_INIT_0 1

static inline void gomp_mutex_init (gomp_mutex_t *mutex)

{

  *mutex = 0;

}

extern void gomp_mutex_lock_slow (gomp_mutex_t *mutex);

static inline void gomp_mutex_lock (gomp_mutex_t *mutex)

{

  if (!__sync_bool_compare_and_swap (mutex, 0, 1))

    gomp_mutex_lock_slow (mutex);

}

extern void gomp_mutex_unlock_slow (gomp_mutex_t *mutex);

static inline void gomp_mutex_unlock (gomp_mutex_t *mutex)

{

  /* Warning: By definition __sync_lock_test_and_set() does not have

     proper memory barrier semantics for a mutex unlock operation.

     However, this default implementation is written assuming that it

     does, which is true for some targets.

     Targets that require additional memory barriers before

     __sync_lock_test_and_set to achieve the release semantics of

     mutex unlock, are encouraged to include

     "config/linux/ia64/mutex.h" in a target specific mutex.h instead

     of using this file.  */

  int val = __sync_lock_test_and_set (mutex, 0);

  if (__builtin_expect (val > 1, 0))

    gomp_mutex_unlock_slow (mutex);

}

static inline void gomp_mutex_destroy (gomp_mutex_t *mutex)

{

}

#endif /* GOMP_MUTEX_H */