| /* Copyright (C) 2005 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 Lesser General Public License as published by |
| the Free Software Foundation; either version 2.1 of the License, 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 Lesser General Public License for |
| more details. |
| |
| You should have received a copy of the GNU Lesser General Public License |
| along with libgomp; see the file COPYING.LIB. If not, write to the |
| Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, |
| MA 02110-1301, USA. */ |
| |
| /* As a special exception, if you link this library with other files, some |
| of which are compiled with GCC, to produce an executable, this library |
| does not by itself cause the resulting executable to be covered by the |
| GNU General Public License. This exception does not however invalidate |
| any other reasons why the executable file might be covered by the GNU |
| General Public License. */ |
| |
| /* This is a Linux specific implementation of a barrier synchronization |
| mechanism for libgomp. This type is private to the library. This |
| implementation uses atomic instructions and the futex syscall. */ |
| |
| #include "libgomp.h" |
| #include "futex.h" |
| #include <limits.h> |
| |
| |
| void |
| gomp_barrier_wait_end (gomp_barrier_t *bar, bool last) |
| { |
| if (last) |
| { |
| bar->generation++; |
| futex_wake (&bar->generation, INT_MAX); |
| } |
| else |
| { |
| unsigned int generation = bar->generation; |
| |
| gomp_mutex_unlock (&bar->mutex); |
| |
| do |
| futex_wait (&bar->generation, generation); |
| while (bar->generation == generation); |
| } |
| |
| if (__sync_add_and_fetch (&bar->arrived, -1) == 0) |
| gomp_mutex_unlock (&bar->mutex); |
| } |
| |
| void |
| gomp_barrier_wait (gomp_barrier_t *barrier) |
| { |
| gomp_barrier_wait_end (barrier, gomp_barrier_wait_start (barrier)); |
| } |