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/* Copyright (C) 2005, 2008, 2009, 2011 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. */
#include "wait.h"
long int gomp_futex_wake = FUTEX_WAKE | FUTEX_PRIVATE_FLAG;
long int gomp_futex_wait = FUTEX_WAIT | FUTEX_PRIVATE_FLAG;
void
gomp_mutex_lock_slow (gomp_mutex_t *mutex, int oldval)
{
while (oldval == 1)
{
if (do_spin (mutex, 1))
{
oldval = __sync_lock_test_and_set (mutex, 2);
if (oldval == 0)
return;
futex_wait (mutex, 2);
break;
}
else
{
oldval = __sync_val_compare_and_swap (mutex, 0, 1);
if (oldval == 0)
return;
}
}
while ((oldval = __sync_lock_test_and_set (mutex, 2)))
do_wait (mutex, 2);
}
void
gomp_mutex_unlock_slow (gomp_mutex_t *mutex)
{
futex_wake (mutex, 1);
}
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