1 // Low-level functions for atomic operations: x86, x >= 3 version -*- C++ -*-
3 // Copyright (C) 2003-2024 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 3, 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 // 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.
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/>.
25 #include <ext/atomicity.h>
27 namespace __gnu_cxx
_GLIBCXX_VISIBILITY(default)
29 _GLIBCXX_BEGIN_NAMESPACE_VERSION
32 struct _Atomicity_lock
34 static volatile _Atomic_word _S_atomicity_lock
;
38 volatile _Atomic_word _Atomicity_lock
<__inst
>::_S_atomicity_lock
= 0;
40 template volatile _Atomic_word _Atomicity_lock
<0>::_S_atomicity_lock
;
43 __attribute__ ((__unused__
))
44 __exchange_and_add(volatile _Atomic_word
* __mem
, int __val
) throw ()
46 register _Atomic_word __result
, __tmp
= 1;
48 // Obtain the atomic exchange/add spin lock.
51 __asm__
__volatile__ ("xchg{l} {%0,%1|%1,%0}"
52 : "=m" (_Atomicity_lock
<0>::_S_atomicity_lock
),
54 : "m" (_Atomicity_lock
<0>::_S_atomicity_lock
));
62 _Atomicity_lock
<0>::_S_atomicity_lock
= 0;
68 __attribute__ ((__unused__
))
69 __atomic_add(volatile _Atomic_word
* __mem
, int __val
) throw ()
70 { __exchange_and_add(__mem
, __val
); }
72 _GLIBCXX_END_NAMESPACE_VERSION