1 | // Support for atomic operations -*- C++ -*- |
2 | |
3 | // Copyright (C) 2004, 2005, 2006, 2008, 2009, 2010, 2011, 2012 |
4 | // Free Software Foundation, Inc. |
5 | // |
6 | // This file is part of the GNU ISO C++ Library. This library is free |
7 | // software; you can redistribute it and/or modify it under the |
8 | // terms of the GNU General Public License as published by the |
9 | // Free Software Foundation; either version 3, or (at your option) |
10 | // any later version. |
11 | |
12 | // This library is distributed in the hope that it will be useful, |
13 | // but WITHOUT ANY WARRANTY; without even the implied warranty of |
14 | // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
15 | // GNU General Public License for more details. |
16 | |
17 | // Under Section 7 of GPL version 3, you are granted additional |
18 | // permissions described in the GCC Runtime Library Exception, version |
19 | // 3.1, as published by the Free Software Foundation. |
20 | |
21 | // You should have received a copy of the GNU General Public License and |
22 | // a copy of the GCC Runtime Library Exception along with this program; |
23 | // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see |
24 | // <http://www.gnu.org/licenses/>. |
25 | |
26 | /** @file ext/atomicity.h |
27 | * This file is a GNU extension to the Standard C++ Library. |
28 | */ |
29 | |
30 | #ifndef _GLIBCXX_ATOMICITY_H |
31 | #define _GLIBCXX_ATOMICITY_H 1 |
32 | |
33 | #include <bits/c++config.h> |
34 | #include <bits/gthr.h> |
35 | #include <bits/atomic_word.h> |
36 | |
37 | namespace __gnu_cxx _GLIBCXX_VISIBILITY(default) |
38 | { |
39 | _GLIBCXX_BEGIN_NAMESPACE_VERSION |
40 | |
41 | // Functions for portable atomic access. |
42 | // To abstract locking primitives across all thread policies, use: |
43 | // __exchange_and_add_dispatch |
44 | // __atomic_add_dispatch |
45 | #ifdef _GLIBCXX_ATOMIC_BUILTINS |
46 | static inline _Atomic_word |
47 | __exchange_and_add(volatile _Atomic_word* __mem, int __val) |
48 | { return __atomic_fetch_add(__mem, __val, __ATOMIC_ACQ_REL); } |
49 | |
50 | static inline void |
51 | __atomic_add(volatile _Atomic_word* __mem, int __val) |
52 | { __atomic_fetch_add(__mem, __val, __ATOMIC_ACQ_REL); } |
53 | #else |
54 | _Atomic_word |
55 | __attribute__ ((__unused__)) |
56 | __exchange_and_add(volatile _Atomic_word*, int) throw (); |
57 | |
58 | void |
59 | __attribute__ ((__unused__)) |
60 | __atomic_add(volatile _Atomic_word*, int) throw (); |
61 | #endif |
62 | |
63 | static inline _Atomic_word |
64 | __exchange_and_add_single(_Atomic_word* __mem, int __val) |
65 | { |
66 | _Atomic_word __result = *__mem; |
67 | *__mem += __val; |
68 | return __result; |
69 | } |
70 | |
71 | static inline void |
72 | __atomic_add_single(_Atomic_word* __mem, int __val) |
73 | { *__mem += __val; } |
74 | |
75 | static inline _Atomic_word |
76 | __attribute__ ((__unused__)) |
77 | __exchange_and_add_dispatch(_Atomic_word* __mem, int __val) |
78 | { |
79 | #ifdef __GTHREADS |
80 | if (__gthread_active_p()) |
81 | return __exchange_and_add(__mem, __val); |
82 | else |
83 | return __exchange_and_add_single(__mem, __val); |
84 | #else |
85 | return __exchange_and_add_single(__mem, __val); |
86 | #endif |
87 | } |
88 | |
89 | static inline void |
90 | __attribute__ ((__unused__)) |
91 | __atomic_add_dispatch(_Atomic_word* __mem, int __val) |
92 | { |
93 | #ifdef __GTHREADS |
94 | if (__gthread_active_p()) |
95 | __atomic_add(__mem, __val); |
96 | else |
97 | __atomic_add_single(__mem, __val); |
98 | #else |
99 | __atomic_add_single(__mem, __val); |
100 | #endif |
101 | } |
102 | |
103 | _GLIBCXX_END_NAMESPACE_VERSION |
104 | } // namespace |
105 | |
106 | // Even if the CPU doesn't need a memory barrier, we need to ensure |
107 | // that the compiler doesn't reorder memory accesses across the |
108 | // barriers. |
109 | #ifndef _GLIBCXX_READ_MEM_BARRIER |
110 | #define _GLIBCXX_READ_MEM_BARRIER __asm __volatile ("":::"memory") |
111 | #endif |
112 | #ifndef _GLIBCXX_WRITE_MEM_BARRIER |
113 | #define _GLIBCXX_WRITE_MEM_BARRIER __asm __volatile ("":::"memory") |
114 | #endif |
115 | |
116 | #endif |
117 | |