1 // Low-level functions for atomic operations: x86, x >= 3 version -*- C++ -*-
3 // Copyright (C) 2003, 2004, 2005 Free Software Foundation, Inc.
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)
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.
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, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
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.
30 #include <ext/atomicity.h>
32 _GLIBCXX_BEGIN_NAMESPACE(__gnu_cxx)
35 struct _Atomicity_lock
37 static volatile _Atomic_word _S_atomicity_lock;
41 volatile _Atomic_word _Atomicity_lock<__inst>::_S_atomicity_lock = 0;
43 template volatile _Atomic_word _Atomicity_lock<0>::_S_atomicity_lock;
46 __attribute__ ((__unused__))
47 __exchange_and_add(volatile _Atomic_word* __mem, int __val)
49 register _Atomic_word __result, __tmp = 1;
51 // Obtain the atomic exchange/add spin lock.
54 __asm__ __volatile__ ("xchg{l} {%0,%1|%1,%0}"
55 : "=m" (_Atomicity_lock<0>::_S_atomicity_lock),
57 : "m" (_Atomicity_lock<0>::_S_atomicity_lock));
65 _Atomicity_lock<0>::_S_atomicity_lock = 0;
71 __attribute__ ((__unused__))
72 __atomic_add(volatile _Atomic_word* __mem, int __val)
73 { __exchange_and_add(__mem, __val); }
75 _GLIBCXX_END_NAMESPACE