1 // Low-level functions for atomic operations: Generic version -*- C++ -*-
2
3 // Copyright (C) 1999, 2001, 2002, 2003 Free Software Foundation, Inc.
4 //
5 // This file is part of the GNU ISO C++ Library. This library is free
6 // software; you can redistribute it and/or modify it under the
7 // terms of the GNU General Public License as published by the
8 // Free Software Foundation; either version 2, or (at your option)
9 // any later version.
10
11 // This library is distributed in the hope that it will be useful,
12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 // GNU General Public License for more details.
15
16 // You should have received a copy of the GNU General Public License along
17 // with this library; see the file COPYING. If not, write to the Free
18 // Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307,
19 // USA.
20
21 // As a special exception, you may use this file as part of a free software
22 // library without restriction. Specifically, if other files instantiate
23 // templates or use macros or inline functions from this file, or you compile
24 // this file and link it with other files to produce an executable, this
25 // file does not by itself cause the resulting executable to be covered by
26 // the GNU General Public License. This exception does not however
27 // invalidate any other reasons why the executable file might be covered by
28 // the GNU General Public License.
29
30 #ifndef _BITS_ATOMICITY_H
31 #define _BITS_ATOMICITY_H 1
32
33 #include <bits/gthr.h>
34
35 #define _GLIBCPP_NEED_GENERIC_MUTEX
36
37 typedef int _Atomic_word;
38
39 namespace __gnu_cxx
40 {
41 extern __gthread_mutex_t _Atomic_add_mutex;
42
43 #ifndef __GTHREAD_MUTEX_INIT
44 extern __gthread_once_t _Atomic_add_mutex_once;
45 extern void __gthread_atomic_add_mutex_once();
46 #endif
47 }
48
49 static inline _Atomic_word
50 __attribute__ ((__unused__))
__exchange_and_add(volatile _Atomic_word * __mem,int __val)51 __exchange_and_add (volatile _Atomic_word* __mem, int __val)
52 {
53 #ifndef __GTHREAD_MUTEX_INIT
54 __gthread_once (&__gnu_cxx::_Atomic_add_mutex_once,
55 __gnu_cxx::__gthread_atomic_add_mutex_once);
56 #endif
57
58 _Atomic_word __result;
59
60 __gthread_mutex_lock (&__gnu_cxx::_Atomic_add_mutex);
61
62 __result = *__mem;
63 *__mem += __val;
64
65 __gthread_mutex_unlock (&__gnu_cxx::_Atomic_add_mutex);
66 return __result;
67 }
68
69
70 static inline void
71 __attribute__ ((__unused__))
__atomic_add(volatile _Atomic_word * __mem,int __val)72 __atomic_add (volatile _Atomic_word* __mem, int __val)
73 {
74 (void) __exchange_and_add (__mem, __val);
75 }
76
77 #endif /* atomicity.h */
78