1 files changed, 61 insertions, 0 deletions
diff --git a/libgomp/config/linux/sem.c b/libgomp/config/linux/sem.c
new file mode 100644
index 000000000..ea981024c
--- /dev/null
+++ b/libgomp/config/linux/sem.c
@@ -0,0 +1,61 @@
+/* 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);
+}