1// Support for atomic operations -*- C++ -*-
2
3// Copyright (C) 2008, 2009
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#include "gstdint.h"
27#include <atomic>
28#include <mutex>
29
30#define LOGSIZE 4
31
32namespace
33{
34#if defined(_GLIBCXX_HAS_GTHREADS) && defined(_GLIBCXX_USE_C99_STDINT_TR1)
35  std::mutex&
36  get_atomic_mutex()
37  {
38    static std::mutex atomic_mutex;
39    return atomic_mutex;
40  }
41#endif
42
43  std::__atomic_flag_base flag_table[ 1 << LOGSIZE ] =
44    {
45      ATOMIC_FLAG_INIT, ATOMIC_FLAG_INIT, ATOMIC_FLAG_INIT, ATOMIC_FLAG_INIT,
46      ATOMIC_FLAG_INIT, ATOMIC_FLAG_INIT, ATOMIC_FLAG_INIT, ATOMIC_FLAG_INIT,
47      ATOMIC_FLAG_INIT, ATOMIC_FLAG_INIT, ATOMIC_FLAG_INIT, ATOMIC_FLAG_INIT,
48      ATOMIC_FLAG_INIT, ATOMIC_FLAG_INIT, ATOMIC_FLAG_INIT, ATOMIC_FLAG_INIT,
49    };
50} // anonymous namespace
51
52namespace std
53{
54  namespace __atomic0
55  {
56    bool
57    atomic_flag::test_and_set(memory_order)
58    {
59#if defined(_GLIBCXX_HAS_GTHREADS) && defined(_GLIBCXX_USE_C99_STDINT_TR1)
60      lock_guard<mutex> __lock(get_atomic_mutex());
61#endif
62      bool result = _M_i;
63      _M_i = true;
64      return result;
65    }
66
67    void
68    atomic_flag::clear(memory_order)
69    {
70#if defined(_GLIBCXX_HAS_GTHREADS) && defined(_GLIBCXX_USE_C99_STDINT_TR1)
71      lock_guard<mutex> __lock(get_atomic_mutex());
72#endif
73      _M_i = false;
74    }
75  }
76
77  extern "C"
78  {
79    bool
80    atomic_flag_test_and_set_explicit(__atomic_flag_base* __a,
81				      memory_order __m) throw()
82    {
83      atomic_flag* d = static_cast<volatile atomic_flag*>(__a);
84      return d->test_and_set(__m);
85    }
86
87    void
88    atomic_flag_clear_explicit(__atomic_flag_base* __a,
89			       memory_order __m) throw()
90    {
91      atomic_flag* d = static_cast<volatile atomic_flag*>(__a);
92      return d->clear(__m);
93    }
94
95    void
96    __atomic_flag_wait_explicit(__atomic_flag_base* __a,
97				memory_order __x) throw()
98    {
99      while (atomic_flag_test_and_set_explicit(__a, __x))
100	{ };
101    }
102
103    __atomic_flag_base*
104    __atomic_flag_for_address(const void* __z) throw()
105    {
106      uintptr_t __u = reinterpret_cast<uintptr_t>(__z);
107      __u += (__u >> 2) + (__u << 4);
108      __u += (__u >> 7) + (__u << 5);
109      __u += (__u >> 17) + (__u << 13);
110      if (sizeof(uintptr_t) > 4)
111	__u += (__u >> 31);
112      __u &= ~((~uintptr_t(0)) << LOGSIZE);
113      return flag_table + __u;
114    }
115  } // extern "C"
116} // namespace std
117
118
119// XXX GLIBCXX_ABI Deprecated
120// gcc-4.5.0
121// <atomic> signature changes
122
123// The rename syntax for default exported names is
124//   asm (".symver name1,exportedname@GLIBCXX_3.4")
125//   asm (".symver name2,exportedname@@GLIBCXX_3.4.5")
126// In the future, GLIBCXX_ABI > 6 should remove all uses of
127// _GLIBCXX_*_SYMVER macros in this file.
128
129#if defined(_GLIBCXX_SYMVER_GNU) && defined(PIC) \
130    && defined(_GLIBCXX_HAVE_AS_SYMVER_DIRECTIVE)
131
132#define _GLIBCXX_ASM_SYMVER(cur, old, version) \
133   asm (".symver " #cur "," #old "@@" #version);
134
135_GLIBCXX_ASM_SYMVER(_ZNSt9__atomic011atomic_flag5clearESt12memory_order, _ZNVSt9__atomic011atomic_flag5clearESt12memory_order, GLIBCXX_3.4.11)
136
137_GLIBCXX_ASM_SYMVER(_ZNSt9__atomic011atomic_flag12test_and_setESt12memory_order, _ZNVSt9__atomic011atomic_flag12test_and_setESt12memory_order, GLIBCXX_3.4.11)
138
139#endif
140