From a6dffc4afcfb78fbb043971ecffdf5a2cfa60989 Mon Sep 17 00:00:00 2001
From: "Neal H. Walfield" <neal@gnu.org>
Date: Thu, 12 May 2005 11:50:42 +0000
Subject: libpthread/

2005-05-12  Neal H. Walfield  <neal@gnu.org>

	* Makefile (SRCS): Add sem-close.c sem-destroy.c sem-getvalue.c
	sem-init.c sem-open.c sem-post.c sem-timedwait.c sem-trywait.c
	sem-unlink.c and sem-wait.c.
	(sysdeps_headers): Add semaphore.h bits/semaphore.h.
	* include/semaphore.h: New file.
	* sysdeps/generic/sem-close.c: New file.
	* sysdeps/generic/sem-destroy.c: New file.
	* sysdeps/generic/sem-getvalue.c: New file.
	* sysdeps/generic/sem-init.c: New file.
	* sysdeps/generic/sem-open.c: New file.
	* sysdeps/generic/sem-post.c: New file.
	* sysdeps/generic/sem-timedwait.c: New file.
	* sysdeps/generic/sem-trywait.c: New file.
	* sysdeps/generic/sem-unlink.c: New file.
	* sysdeps/generic/sem-wait.c: New file.
	* sysdeps/generic/bits/semaphore.h: New file.
---
 sysdeps/generic/sem-post.c | 62 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 62 insertions(+)
 create mode 100644 sysdeps/generic/sem-post.c

(limited to 'sysdeps/generic/sem-post.c')

diff --git a/sysdeps/generic/sem-post.c b/sysdeps/generic/sem-post.c
new file mode 100644
index 0000000..c283784
--- /dev/null
+++ b/sysdeps/generic/sem-post.c
@@ -0,0 +1,62 @@
+/* Post a semaphore.  Generic version.
+   Copyright (C) 2005 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Library General Public License as
+   published by the Free Software Foundation; either version 2 of the
+   License, or (at your option) any later version.
+
+   The GNU C Library 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
+   Library General Public License for more details.
+
+   You should have received a copy of the GNU Library General Public
+   License along with the GNU C Library; see the file COPYING.LIB.  If not,
+   write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+   Boston, MA 02111-1307, USA.  */
+
+#include <semaphore.h>
+#include <assert.h>
+
+#include <pt-internal.h>
+
+int
+__sem_post (sem_t *sem)
+{
+  struct __pthread *wakeup;
+
+  __pthread_spin_lock (&sem->__lock);
+  if (sem->__value > 0)
+    /* Do a quick up.  */
+    {
+      assert (! sem->__queue);
+      sem->__value ++;
+      __pthread_spin_unlock (&sem->__lock);
+      return 0;
+    }
+
+  if (! sem->__queue)
+    /* No one waiting.  */
+    {
+      sem->__value = 1;
+      __pthread_spin_unlock (&sem->__lock);
+      return 0;
+    }
+
+  /* Wake someone up.  */
+
+  /* First dequeue someone.  */
+  wakeup = sem->__queue;
+  __pthread_dequeue (wakeup);
+
+  /* Then drop the lock and transfer control.  */
+  __pthread_spin_unlock (&sem->__lock);
+
+  __pthread_wakeup (wakeup);
+
+  return 0;
+}
+
+weak_alias (__sem_post, sem_post);
-- 
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