libstdc++-v3/src/c++11/compatibility-atomic-c++0x.cc

// <atomic> compatibility -*- C++ -*-

// Copyright (C) 2008-2026 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library.  This library is free
// software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 3, or (at your option)
// any later version.

// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// Under Section 7 of GPL version 3, you are granted additional
// permissions described in the GCC Runtime Library Exception, version
// 3.1, as published by the Free Software Foundation.

// You should have received a copy of the GNU General Public License and
// a copy of the GCC Runtime Library Exception along with this program;
// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
// <http://www.gnu.org/licenses/>.

#include <atomic>
#include <mutex>

// XXX GLIBCXX_ABI Deprecated
// gcc-4.7.0

#ifdef _GLIBCXX_SHARED

#define LOGSIZE 4

namespace
{
#if defined(_GLIBCXX_HAS_GTHREADS) && defined(_GLIBCXX_USE_C99_STDINT_TR1)
  std::mutex&
  get_atomic_mutex()
  {
    static std::mutex atomic_mutex;
    return atomic_mutex;
  }
#endif

  std::__atomic_flag_base flag_table[ 1 << LOGSIZE ] =
    {
      ATOMIC_FLAG_INIT, ATOMIC_FLAG_INIT, ATOMIC_FLAG_INIT, ATOMIC_FLAG_INIT,
      ATOMIC_FLAG_INIT, ATOMIC_FLAG_INIT, ATOMIC_FLAG_INIT, ATOMIC_FLAG_INIT,
      ATOMIC_FLAG_INIT, ATOMIC_FLAG_INIT, ATOMIC_FLAG_INIT, ATOMIC_FLAG_INIT,
      ATOMIC_FLAG_INIT, ATOMIC_FLAG_INIT, ATOMIC_FLAG_INIT, ATOMIC_FLAG_INIT,
    };
} // anonymous namespace

namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION

  namespace __atomic0
  {

    struct atomic_flag : public __atomic_flag_base
    {
     bool
     test_and_set(memory_order) noexcept;

     void
     clear(memory_order) noexcept;
    };

    bool
    atomic_flag::test_and_set(memory_order) noexcept
    {
#if defined(_GLIBCXX_HAS_GTHREADS) && defined(_GLIBCXX_USE_C99_STDINT_TR1)
      lock_guard<mutex> __lock(get_atomic_mutex());
#endif
      bool result = _M_i;
      _M_i = true;
      return result;
    }

    void
    atomic_flag::clear(memory_order) noexcept
    {
#if defined(_GLIBCXX_HAS_GTHREADS) && defined(_GLIBCXX_USE_C99_STDINT_TR1)
      lock_guard<mutex> __lock(get_atomic_mutex());
#endif
      _M_i = false;
    }
  } // namespace __atomic0

  _GLIBCXX_BEGIN_EXTERN_C

  bool
  atomic_flag_test_and_set_explicit(__atomic_flag_base* __a,
				    memory_order __m) _GLIBCXX_NOTHROW
  {
    atomic_flag* d = static_cast<atomic_flag*>(__a);
    return d->test_and_set(__m);
  }

  void
  atomic_flag_clear_explicit(__atomic_flag_base* __a,
			     memory_order __m) _GLIBCXX_NOTHROW
  {
    atomic_flag* d = static_cast<atomic_flag*>(__a);
    return d->clear(__m);
  }

  void
  __atomic_flag_wait_explicit(__atomic_flag_base* __a,
			      memory_order __x) _GLIBCXX_NOTHROW
  {
    while (atomic_flag_test_and_set_explicit(__a, __x))
      { };
  }

  _GLIBCXX_CONST __atomic_flag_base*
  __atomic_flag_for_address(const volatile void* __z) _GLIBCXX_NOTHROW
  {
    using guintptr_t = __UINTPTR_TYPE__;
    guintptr_t __u = reinterpret_cast<guintptr_t>(__z);
    __u += (__u >> 2) + (__u << 4);
    __u += (__u >> 7) + (__u << 5);
    __u += (__u >> 17) + (__u << 13);
    if (sizeof(guintptr_t) > 4)
      __u += (__u >> 31);
    __u &= ~((~guintptr_t(0)) << LOGSIZE);
    return flag_table + __u;
  }

  _GLIBCXX_END_EXTERN_C

_GLIBCXX_END_NAMESPACE_VERSION
} // namespace std

#endif

// XXX GLIBCXX_ABI Deprecated
// gcc-4.5.0
// <atomic> signature changes

// The rename syntax for default exported names is
//   asm (".symver name1,exportedname@GLIBCXX_3.4")
//   asm (".symver name2,exportedname@@GLIBCXX_3.4.5")
// In the future, GLIBCXX_ABI > 6 should remove all uses of
// _GLIBCXX_*_SYMVER macros in this file.

#if defined(_GLIBCXX_SYMVER_GNU) && defined(_GLIBCXX_SHARED) \
    && defined(_GLIBCXX_HAVE_AS_SYMVER_DIRECTIVE) \
    && defined(_GLIBCXX_HAVE_SYMVER_SYMBOL_RENAMING_RUNTIME_SUPPORT)

#define _GLIBCXX_ASM_SYMVER(cur, old, version) \
   asm (".symver " #cur "," #old "@@" #version);

_GLIBCXX_ASM_SYMVER(_ZNSt9__atomic011atomic_flag5clearESt12memory_order, _ZNVSt9__atomic011atomic_flag5clearESt12memory_order, GLIBCXX_3.4.11)

_GLIBCXX_ASM_SYMVER(_ZNSt9__atomic011atomic_flag12test_and_setESt12memory_order, _ZNVSt9__atomic011atomic_flag12test_and_setESt12memory_order, GLIBCXX_3.4.11)

#endif