1// Low-level functions for atomic operations: Generic version  -*- C++ -*-
2
3// Copyright (C) 1999-2022 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 3, 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// Under Section 7 of GPL version 3, you are granted additional
17// permissions described in the GCC Runtime Library Exception, version
18// 3.1, as published by the Free Software Foundation.
19
20// You should have received a copy of the GNU General Public License and
21// a copy of the GCC Runtime Library Exception along with this program;
22// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
23// <http://www.gnu.org/licenses/>.
24
25#include <ext/atomicity.h>
26#include <ext/concurrence.h>
27
28namespace
29{
30  __gnu_cxx::__mutex&
31  get_atomic_mutex()
32  {
33    static __gnu_cxx::__mutex atomic_mutex;
34    return atomic_mutex;
35  }
36} // anonymous namespace
37
38namespace __gnu_cxx _GLIBCXX_VISIBILITY(default)
39{
40_GLIBCXX_BEGIN_NAMESPACE_VERSION
41
42  _Atomic_word
43  __attribute__ ((__unused__))
44  __exchange_and_add(volatile _Atomic_word* __mem, int __val) throw ()
45  {
46    __gnu_cxx::__scoped_lock sentry(get_atomic_mutex());
47    _Atomic_word __result;
48    __result = *__mem;
49    *__mem += __val;
50    return __result;
51  }
52
53  void
54  __attribute__ ((__unused__))
55  __atomic_add(volatile _Atomic_word* __mem, int __val) throw ()
56  { __exchange_and_add(__mem, __val); }
57
58_GLIBCXX_END_NAMESPACE_VERSION
59} // namespace
60