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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 */
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