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[/] [openrisc/] [trunk/] [gnu-stable/] [gcc-4.5.1/] [libgomp/] [config/] [linux/] [sem.c] - Rev 859
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/* Copyright (C) 2005, 2008, 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 semaphore synchronization mechanism for libgomp. This type is private to the library. This implementation uses atomic instructions and the futex syscall. */ #include "wait.h" void gomp_sem_wait_slow (gomp_sem_t *sem) { while (1) { int val = __sync_val_compare_and_swap (sem, 0, -1); if (val > 0) { if (__sync_bool_compare_and_swap (sem, val, val - 1)) return; } do_wait (sem, -1); } } void gomp_sem_post_slow (gomp_sem_t *sem) { int old, tmp = *sem, wake; do { old = tmp; wake = old > 0 ? old + 1 : 1; tmp = __sync_val_compare_and_swap (sem, old, wake); } while (old != tmp); futex_wake (sem, wake); }
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