1*e4b17023SJohn Marino // Low-level functions for atomic operations: x86, x >= 3 version -*- C++ -*-
2*e4b17023SJohn Marino
3*e4b17023SJohn Marino // Copyright (C) 2003, 2004, 2005, 2009 Free Software Foundation, Inc.
4*e4b17023SJohn Marino //
5*e4b17023SJohn Marino // This file is part of the GNU ISO C++ Library. This library is free
6*e4b17023SJohn Marino // software; you can redistribute it and/or modify it under the
7*e4b17023SJohn Marino // terms of the GNU General Public License as published by the
8*e4b17023SJohn Marino // Free Software Foundation; either version 3, or (at your option)
9*e4b17023SJohn Marino // any later version.
10*e4b17023SJohn Marino
11*e4b17023SJohn Marino // This library is distributed in the hope that it will be useful,
12*e4b17023SJohn Marino // but WITHOUT ANY WARRANTY; without even the implied warranty of
13*e4b17023SJohn Marino // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14*e4b17023SJohn Marino // GNU General Public License for more details.
15*e4b17023SJohn Marino
16*e4b17023SJohn Marino // Under Section 7 of GPL version 3, you are granted additional
17*e4b17023SJohn Marino // permissions described in the GCC Runtime Library Exception, version
18*e4b17023SJohn Marino // 3.1, as published by the Free Software Foundation.
19*e4b17023SJohn Marino
20*e4b17023SJohn Marino // You should have received a copy of the GNU General Public License and
21*e4b17023SJohn Marino // a copy of the GCC Runtime Library Exception along with this program;
22*e4b17023SJohn Marino // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
23*e4b17023SJohn Marino // <http://www.gnu.org/licenses/>.
24*e4b17023SJohn Marino
25*e4b17023SJohn Marino #include <ext/atomicity.h>
26*e4b17023SJohn Marino
_GLIBCXX_VISIBILITY(default)27*e4b17023SJohn Marino namespace __gnu_cxx _GLIBCXX_VISIBILITY(default)
28*e4b17023SJohn Marino {
29*e4b17023SJohn Marino _GLIBCXX_BEGIN_NAMESPACE_VERSION
30*e4b17023SJohn Marino
31*e4b17023SJohn Marino template<int __inst>
32*e4b17023SJohn Marino struct _Atomicity_lock
33*e4b17023SJohn Marino {
34*e4b17023SJohn Marino static volatile _Atomic_word _S_atomicity_lock;
35*e4b17023SJohn Marino };
36*e4b17023SJohn Marino
37*e4b17023SJohn Marino template<int __inst>
38*e4b17023SJohn Marino volatile _Atomic_word _Atomicity_lock<__inst>::_S_atomicity_lock = 0;
39*e4b17023SJohn Marino
40*e4b17023SJohn Marino template volatile _Atomic_word _Atomicity_lock<0>::_S_atomicity_lock;
41*e4b17023SJohn Marino
42*e4b17023SJohn Marino _Atomic_word
43*e4b17023SJohn Marino __attribute__ ((__unused__))
44*e4b17023SJohn Marino __exchange_and_add(volatile _Atomic_word* __mem, int __val) throw ()
45*e4b17023SJohn Marino {
46*e4b17023SJohn Marino register _Atomic_word __result, __tmp = 1;
47*e4b17023SJohn Marino
48*e4b17023SJohn Marino // Obtain the atomic exchange/add spin lock.
49*e4b17023SJohn Marino do
50*e4b17023SJohn Marino {
51*e4b17023SJohn Marino __asm__ __volatile__ ("xchg{l} {%0,%1|%1,%0}"
52*e4b17023SJohn Marino : "=m" (_Atomicity_lock<0>::_S_atomicity_lock),
53*e4b17023SJohn Marino "+r" (__tmp)
54*e4b17023SJohn Marino : "m" (_Atomicity_lock<0>::_S_atomicity_lock));
55*e4b17023SJohn Marino }
56*e4b17023SJohn Marino while (__tmp);
57*e4b17023SJohn Marino
58*e4b17023SJohn Marino __result = *__mem;
59*e4b17023SJohn Marino *__mem += __val;
60*e4b17023SJohn Marino
61*e4b17023SJohn Marino // Release spin lock.
62*e4b17023SJohn Marino _Atomicity_lock<0>::_S_atomicity_lock = 0;
63*e4b17023SJohn Marino
64*e4b17023SJohn Marino return __result;
65*e4b17023SJohn Marino }
66*e4b17023SJohn Marino
67*e4b17023SJohn Marino void
68*e4b17023SJohn Marino __attribute__ ((__unused__))
69*e4b17023SJohn Marino __atomic_add(volatile _Atomic_word* __mem, int __val) throw ()
70*e4b17023SJohn Marino { __exchange_and_add(__mem, __val); }
71*e4b17023SJohn Marino
72*e4b17023SJohn Marino _GLIBCXX_END_NAMESPACE_VERSION
73*e4b17023SJohn Marino } // namespace
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