atomicity.h: Provide atomic __exchange_and_add and __atomic_add.

2002-11-07  Phil Edwards  <pme@gcc.gnu.org>
            Richard Earnshaw  <rearnsha@arm.com>

	* config/cpu/generic/atomicity.h:  Provide atomic __exchange_and_add
	and __atomic_add.

Co-Authored-By: Richard Earnshaw <rearnsha@arm.com>

From-SVN: r58929

libstdc++-v3/ChangeLog

+2002-11-07  Phil Edwards  <pme@gcc.gnu.org>
+            Richard Earnshaw  <rearnsha@arm.com>
+
+	* config/cpu/generic/atomicity.h:  Provide atomic __exchange_and_add
+	and __atomic_add.
+
 2002-11-08  Paolo Carlini  <pcarlini@unitus.it>
 
 	* config/locale/gnu/monetary_members.cc

libstdc++-v3/config/cpu/generic/atomicity.h

 // Low-level functions for atomic operations: Generic version  -*- C++ -*-
 
-// Copyright (C) 1999, 2001 Free Software Foundation, Inc.
+// Copyright (C) 1999, 2001, 2002 Free Software Foundation, Inc.
 //
 // This file is part of the GNU ISO C++ Library.  This library is free
 // software; you can redistribute it and/or modify it under the
@@ -30,22 +30,37 @@
 #ifndef _BITS_ATOMICITY_H
 #define _BITS_ATOMICITY_H	1
 
+#include <bits/gthr.h>
+
 typedef int _Atomic_word;
 
+namespace __gnu_cxx
+{
+  __gthread_mutex_t _Atomic_add_mutex __attribute__ ((__weak__))
+                                                      = __GTHREAD_MUTEX_INIT;
+}
+
 static inline _Atomic_word
 __attribute__ ((__unused__))
-__exchange_and_add (_Atomic_word* __mem, int __val)
+__exchange_and_add (volatile _Atomic_word* __mem, int __val)
 {
-  _Atomic_word __result = *__mem;
-  *__mem += __val;
+   _Atomic_word __result;
+
+   __gthread_mutex_lock (&__gnu_cxx::_Atomic_add_mutex);
+
+   __result = *__mem;
+   *__mem += __val;
+
+  __gthread_mutex_unlock (&__gnu_cxx::_Atomic_add_mutex);
   return __result;
 }
 
+
 static inline void
 __attribute__ ((__unused__))
-__atomic_add (_Atomic_word* __mem, int __val)
+__atomic_add (volatile _Atomic_word* __mem, int __val)
 {
-  *__mem += __val;
+  (void) __exchange_and_add (__mem, __val);
 }
 
 #endif /* atomicity.h */