1 // Low-level functions for atomic operations: x86, x >= 4 version -*- C++ -*-
2
3 // Copyright (C) 1999-2017 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
_GLIBCXX_VISIBILITY(default)27 namespace __gnu_cxx _GLIBCXX_VISIBILITY(default)
28 {
29 _GLIBCXX_BEGIN_NAMESPACE_VERSION
30
31 _Atomic_word
32 __attribute__ ((__unused__))
33 __exchange_and_add(volatile _Atomic_word* __mem, int __val) throw ()
34 {
35 register _Atomic_word __result;
36 __asm__ __volatile__ ("lock; xadd{l} {%0,%1|%1,%0}"
37 : "=r" (__result), "=m" (*__mem)
38 : "0" (__val), "m" (*__mem));
39 return __result;
40 }
41
42 void
43 __attribute__ ((__unused__))
44 __atomic_add(volatile _Atomic_word* __mem, int __val) throw ()
45 {
46 __asm__ __volatile__ ("lock; add{l} {%1,%0|%0,%1}"
47 : "=m" (*__mem) : "ir" (__val), "m" (*__mem));
48 }
49
50 _GLIBCXX_END_NAMESPACE_VERSION
51 } // namespace
52
53