atomic

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// -*- C++ -*- header.

// Copyright (C) 2008-2014 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/>.

/** @file include/atomic
 *  This is a Standard C++ Library header.
 */

// Based on "C++ Atomic Types and Operations" by Hans Boehm and Lawrence Crowl.
// http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2427.html

#ifndef _GLIBCXX_ATOMIC
#define _GLIBCXX_ATOMIC 1

#pragma GCC system_header

#if __cplusplus < 201103L
# include <bits/c++0x_warning.h>
#endif

#include <bits/atomic_base.h>

namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION

  /**
   * @addtogroup atomics
   * @{
   */

  /// atomic_bool
  // NB: No operators or fetch-operations for this type.
  struct atomic_bool
  {
  private:
    __atomic_base<bool> _M_base;

  public:
    atomic_bool() noexcept = default;
    ~atomic_bool() noexcept = default;
    atomic_bool(const atomic_bool&) = delete;
    atomic_bool& operator=(const atomic_bool&) = delete;
    atomic_bool& operator=(const atomic_bool&) volatile = delete;

    constexpr atomic_bool(bool __i) noexcept : _M_base(__i) { }

    bool
    operator=(bool __i) noexcept
    { return _M_base.operator=(__i); }

    bool
    operator=(bool __i) volatile noexcept
    { return _M_base.operator=(__i); }

    operator bool() const noexcept
    { return _M_base.load(); }

    operator bool() const volatile noexcept
    { return _M_base.load(); }

    bool
    is_lock_free() const noexcept { return _M_base.is_lock_free(); }

    bool
    is_lock_free() const volatile noexcept { return _M_base.is_lock_free(); }

    void
    store(bool __i, memory_order __m = memory_order_seq_cst) noexcept
    { _M_base.store(__i, __m); }

    void
    store(bool __i, memory_order __m = memory_order_seq_cst) volatile noexcept
    { _M_base.store(__i, __m); }

    bool
    load(memory_order __m = memory_order_seq_cst) const noexcept
    { return _M_base.load(__m); }

    bool
    load(memory_order __m = memory_order_seq_cst) const volatile noexcept
    { return _M_base.load(__m); }

    bool
    exchange(bool __i, memory_order __m = memory_order_seq_cst) noexcept
    { return _M_base.exchange(__i, __m); }

    bool
    exchange(bool __i,
         memory_order __m = memory_order_seq_cst) volatile noexcept
    { return _M_base.exchange(__i, __m); }

    bool
    compare_exchange_weak(bool& __i1, bool __i2, memory_order __m1,
              memory_order __m2) noexcept
    { return _M_base.compare_exchange_weak(__i1, __i2, __m1, __m2); }

    bool
    compare_exchange_weak(bool& __i1, bool __i2, memory_order __m1,
              memory_order __m2) volatile noexcept
    { return _M_base.compare_exchange_weak(__i1, __i2, __m1, __m2); }

    bool
    compare_exchange_weak(bool& __i1, bool __i2,
              memory_order __m = memory_order_seq_cst) noexcept
    { return _M_base.compare_exchange_weak(__i1, __i2, __m); }

    bool
    compare_exchange_weak(bool& __i1, bool __i2,
             memory_order __m = memory_order_seq_cst) volatile noexcept
    { return _M_base.compare_exchange_weak(__i1, __i2, __m); }

    bool
    compare_exchange_strong(bool& __i1, bool __i2, memory_order __m1,
                memory_order __m2) noexcept
    { return _M_base.compare_exchange_strong(__i1, __i2, __m1, __m2); }

    bool
    compare_exchange_strong(bool& __i1, bool __i2, memory_order __m1,
                memory_order __m2) volatile noexcept
    { return _M_base.compare_exchange_strong(__i1, __i2, __m1, __m2); }

    bool
    compare_exchange_strong(bool& __i1, bool __i2,
                memory_order __m = memory_order_seq_cst) noexcept
    { return _M_base.compare_exchange_strong(__i1, __i2, __m); }

    bool
    compare_exchange_strong(bool& __i1, bool __i2,
            memory_order __m = memory_order_seq_cst) volatile noexcept
    { return _M_base.compare_exchange_strong(__i1, __i2, __m); }
  };


  /**
   *  @brief Generic atomic type, primary class template.
   *
   *  @tparam _Tp  Type to be made atomic, must be trivally copyable.
   */
  template<typename _Tp>
    struct atomic
    {
    private:
      _Tp _M_i;

    public:
      atomic() noexcept = default;
      ~atomic() noexcept = default;
      atomic(const atomic&) = delete;
      atomic& operator=(const atomic&) = delete;
      atomic& operator=(const atomic&) volatile = delete;

      constexpr atomic(_Tp __i) noexcept : _M_i(__i) { }

      operator _Tp() const noexcept
      { return load(); }

      operator _Tp() const volatile noexcept
      { return load(); }

      _Tp
      operator=(_Tp __i) noexcept 
      { store(__i); return __i; }

      _Tp
      operator=(_Tp __i) volatile noexcept 
      { store(__i); return __i; }

      bool
      is_lock_free() const noexcept
      { return __atomic_is_lock_free(sizeof(_M_i), nullptr); }

      bool
      is_lock_free() const volatile noexcept
      { return __atomic_is_lock_free(sizeof(_M_i), nullptr); }

      void
      store(_Tp __i, memory_order _m = memory_order_seq_cst) noexcept
      { __atomic_store(&_M_i, &__i, _m); }

      void
      store(_Tp __i, memory_order _m = memory_order_seq_cst) volatile noexcept
      { __atomic_store(&_M_i, &__i, _m); }

      _Tp
      load(memory_order _m = memory_order_seq_cst) const noexcept
      { 
        _Tp tmp;
    __atomic_load(&_M_i, &tmp, _m); 
    return tmp;
      }

      _Tp
      load(memory_order _m = memory_order_seq_cst) const volatile noexcept
      { 
        _Tp tmp;
    __atomic_load(&_M_i, &tmp, _m); 
    return tmp;
      }

      _Tp
      exchange(_Tp __i, memory_order _m = memory_order_seq_cst) noexcept
      { 
        _Tp tmp;
    __atomic_exchange(&_M_i, &__i, &tmp, _m); 
    return tmp;
      }

      _Tp
      exchange(_Tp __i, 
           memory_order _m = memory_order_seq_cst) volatile noexcept
      { 
        _Tp tmp;
    __atomic_exchange(&_M_i, &__i, &tmp, _m); 
    return tmp;
      }

      bool
      compare_exchange_weak(_Tp& __e, _Tp __i, memory_order __s, 
                memory_order __f) noexcept
      {
    return __atomic_compare_exchange(&_M_i, &__e, &__i, true, __s, __f); 
      }

      bool
      compare_exchange_weak(_Tp& __e, _Tp __i, memory_order __s, 
                memory_order __f) volatile noexcept
      {
    return __atomic_compare_exchange(&_M_i, &__e, &__i, true, __s, __f); 
      }

      bool
      compare_exchange_weak(_Tp& __e, _Tp __i,
                memory_order __m = memory_order_seq_cst) noexcept
      { return compare_exchange_weak(__e, __i, __m,
                                     __cmpexch_failure_order(__m)); }

      bool
      compare_exchange_weak(_Tp& __e, _Tp __i,
             memory_order __m = memory_order_seq_cst) volatile noexcept
      { return compare_exchange_weak(__e, __i, __m,
                                     __cmpexch_failure_order(__m)); }

      bool
      compare_exchange_strong(_Tp& __e, _Tp __i, memory_order __s, 
                  memory_order __f) noexcept
      {
    return __atomic_compare_exchange(&_M_i, &__e, &__i, false, __s, __f); 
      }

      bool
      compare_exchange_strong(_Tp& __e, _Tp __i, memory_order __s, 
                  memory_order __f) volatile noexcept
      {
    return __atomic_compare_exchange(&_M_i, &__e, &__i, false, __s, __f); 
      }

      bool
      compare_exchange_strong(_Tp& __e, _Tp __i,
                   memory_order __m = memory_order_seq_cst) noexcept
      { return compare_exchange_strong(__e, __i, __m,
                                       __cmpexch_failure_order(__m)); }

      bool
      compare_exchange_strong(_Tp& __e, _Tp __i,
             memory_order __m = memory_order_seq_cst) volatile noexcept
      { return compare_exchange_strong(__e, __i, __m,
                                       __cmpexch_failure_order(__m)); }
    };


  /// Partial specialization for pointer types.
  template<typename _Tp>
    struct atomic<_Tp*>
    {
      typedef _Tp*          __pointer_type;
      typedef __atomic_base<_Tp*>   __base_type;
      __base_type           _M_b;

      atomic() noexcept = default;
      ~atomic() noexcept = default;
      atomic(const atomic&) = delete;
      atomic& operator=(const atomic&) = delete;
      atomic& operator=(const atomic&) volatile = delete;

      constexpr atomic(__pointer_type __p) noexcept : _M_b(__p) { }

      operator __pointer_type() const noexcept
      { return __pointer_type(_M_b); }

      operator __pointer_type() const volatile noexcept
      { return __pointer_type(_M_b); }

      __pointer_type
      operator=(__pointer_type __p) noexcept
      { return _M_b.operator=(__p); }

      __pointer_type
      operator=(__pointer_type __p) volatile noexcept
      { return _M_b.operator=(__p); }

      __pointer_type
      operator++(int) noexcept
      { return _M_b++; }

      __pointer_type
      operator++(int) volatile noexcept
      { return _M_b++; }

      __pointer_type
      operator--(int) noexcept
      { return _M_b--; }

      __pointer_type
      operator--(int) volatile noexcept
      { return _M_b--; }

      __pointer_type
      operator++() noexcept
      { return ++_M_b; }

      __pointer_type
      operator++() volatile noexcept
      { return ++_M_b; }

      __pointer_type
      operator--() noexcept
      { return --_M_b; }

      __pointer_type
      operator--() volatile noexcept
      { return --_M_b; }

      __pointer_type
      operator+=(ptrdiff_t __d) noexcept
      { return _M_b.operator+=(__d); }

      __pointer_type
      operator+=(ptrdiff_t __d) volatile noexcept
      { return _M_b.operator+=(__d); }

      __pointer_type
      operator-=(ptrdiff_t __d) noexcept
      { return _M_b.operator-=(__d); }

      __pointer_type
      operator-=(ptrdiff_t __d) volatile noexcept
      { return _M_b.operator-=(__d); }

      bool
      is_lock_free() const noexcept
      { return _M_b.is_lock_free(); }

      bool
      is_lock_free() const volatile noexcept
      { return _M_b.is_lock_free(); }

      void
      store(__pointer_type __p,
        memory_order __m = memory_order_seq_cst) noexcept
      { return _M_b.store(__p, __m); }

      void
      store(__pointer_type __p,
        memory_order __m = memory_order_seq_cst) volatile noexcept
      { return _M_b.store(__p, __m); }

      __pointer_type
      load(memory_order __m = memory_order_seq_cst) const noexcept
      { return _M_b.load(__m); }

      __pointer_type
      load(memory_order __m = memory_order_seq_cst) const volatile noexcept
      { return _M_b.load(__m); }

      __pointer_type
      exchange(__pointer_type __p,
           memory_order __m = memory_order_seq_cst) noexcept
      { return _M_b.exchange(__p, __m); }

      __pointer_type
      exchange(__pointer_type __p,
           memory_order __m = memory_order_seq_cst) volatile noexcept
      { return _M_b.exchange(__p, __m); }

      bool
      compare_exchange_weak(__pointer_type& __p1, __pointer_type __p2,
                memory_order __m1, memory_order __m2) noexcept
      { return _M_b.compare_exchange_strong(__p1, __p2, __m1, __m2); }

      bool
      compare_exchange_weak(__pointer_type& __p1, __pointer_type __p2,
                memory_order __m1,
                memory_order __m2) volatile noexcept
      { return _M_b.compare_exchange_strong(__p1, __p2, __m1, __m2); }

      bool
      compare_exchange_weak(__pointer_type& __p1, __pointer_type __p2,
                memory_order __m = memory_order_seq_cst) noexcept
      {
    return compare_exchange_weak(__p1, __p2, __m,
                     __cmpexch_failure_order(__m));
      }

      bool
      compare_exchange_weak(__pointer_type& __p1, __pointer_type __p2,
            memory_order __m = memory_order_seq_cst) volatile noexcept
      {
    return compare_exchange_weak(__p1, __p2, __m,
                     __cmpexch_failure_order(__m));
      }

      bool
      compare_exchange_strong(__pointer_type& __p1, __pointer_type __p2,
                  memory_order __m1, memory_order __m2) noexcept
      { return _M_b.compare_exchange_strong(__p1, __p2, __m1, __m2); }

      bool
      compare_exchange_strong(__pointer_type& __p1, __pointer_type __p2,
                  memory_order __m1,
                  memory_order __m2) volatile noexcept
      { return _M_b.compare_exchange_strong(__p1, __p2, __m1, __m2); }

      bool
      compare_exchange_strong(__pointer_type& __p1, __pointer_type __p2,
                  memory_order __m = memory_order_seq_cst) noexcept
      {
    return _M_b.compare_exchange_strong(__p1, __p2, __m,
                        __cmpexch_failure_order(__m));
      }

      bool
      compare_exchange_strong(__pointer_type& __p1, __pointer_type __p2,
            memory_order __m = memory_order_seq_cst) volatile noexcept
      {
    return _M_b.compare_exchange_strong(__p1, __p2, __m,
                        __cmpexch_failure_order(__m));
      }

      __pointer_type
      fetch_add(ptrdiff_t __d,
        memory_order __m = memory_order_seq_cst) noexcept
      { return _M_b.fetch_add(__d, __m); }

      __pointer_type
      fetch_add(ptrdiff_t __d,
        memory_order __m = memory_order_seq_cst) volatile noexcept
      { return _M_b.fetch_add(__d, __m); }

      __pointer_type
      fetch_sub(ptrdiff_t __d,
        memory_order __m = memory_order_seq_cst) noexcept
      { return _M_b.fetch_sub(__d, __m); }

      __pointer_type
      fetch_sub(ptrdiff_t __d,
        memory_order __m = memory_order_seq_cst) volatile noexcept
      { return _M_b.fetch_sub(__d, __m); }
    };


  /// Explicit specialization for bool.
  template<>
    struct atomic<bool> : public atomic_bool
    {
      typedef bool          __integral_type;
      typedef atomic_bool       __base_type;

      atomic() noexcept = default;
      ~atomic() noexcept = default;
      atomic(const atomic&) = delete;
      atomic& operator=(const atomic&) = delete;
      atomic& operator=(const atomic&) volatile = delete;

      constexpr atomic(__integral_type __i) noexcept : __base_type(__i) { }

      using __base_type::operator __integral_type;
      using __base_type::operator=;
    };

  /// Explicit specialization for char.
  template<>
    struct atomic<char> : public atomic_char
    {
      typedef char          __integral_type;
      typedef atomic_char       __base_type;

      atomic() noexcept = default;
      ~atomic() noexcept = default;
      atomic(const atomic&) = delete;
      atomic& operator=(const atomic&) = delete;
      atomic& operator=(const atomic&) volatile = delete;

      constexpr atomic(__integral_type __i) noexcept : __base_type(__i) { }

      using __base_type::operator __integral_type;
      using __base_type::operator=;
    };

  /// Explicit specialization for signed char.
  template<>
    struct atomic<signed char> : public atomic_schar
    {
      typedef signed char       __integral_type;
      typedef atomic_schar      __base_type;

      atomic() noexcept= default;
      ~atomic() noexcept = default;
      atomic(const atomic&) = delete;
      atomic& operator=(const atomic&) = delete;
      atomic& operator=(const atomic&) volatile = delete;

      constexpr atomic(__integral_type __i) noexcept : __base_type(__i) { }

      using __base_type::operator __integral_type;
      using __base_type::operator=;
    };

  /// Explicit specialization for unsigned char.
  template<>
    struct atomic<unsigned char> : public atomic_uchar
    {
      typedef unsigned char         __integral_type;
      typedef atomic_uchar      __base_type;

      atomic() noexcept= default;
      ~atomic() noexcept = default;
      atomic(const atomic&) = delete;
      atomic& operator=(const atomic&) = delete;
      atomic& operator=(const atomic&) volatile = delete;

      constexpr atomic(__integral_type __i) noexcept : __base_type(__i) { }

      using __base_type::operator __integral_type;
      using __base_type::operator=;
    };

  /// Explicit specialization for short.
  template<>
    struct atomic<short> : public atomic_short
    {
      typedef short             __integral_type;
      typedef atomic_short      __base_type;

      atomic() noexcept = default;
      ~atomic() noexcept = default;
      atomic(const atomic&) = delete;
      atomic& operator=(const atomic&) = delete;
      atomic& operator=(const atomic&) volatile = delete;

      constexpr atomic(__integral_type __i) noexcept : __base_type(__i) { }

      using __base_type::operator __integral_type;
      using __base_type::operator=;
    };

  /// Explicit specialization for unsigned short.
  template<>
    struct atomic<unsigned short> : public atomic_ushort
    {
      typedef unsigned short            __integral_type;
      typedef atomic_ushort         __base_type;

      atomic() noexcept = default;
      ~atomic() noexcept = default;
      atomic(const atomic&) = delete;
      atomic& operator=(const atomic&) = delete;
      atomic& operator=(const atomic&) volatile = delete;

      constexpr atomic(__integral_type __i) noexcept : __base_type(__i) { }

      using __base_type::operator __integral_type;
      using __base_type::operator=;
    };

  /// Explicit specialization for int.
  template<>
    struct atomic<int> : atomic_int
    {
      typedef int           __integral_type;
      typedef atomic_int        __base_type;

      atomic() noexcept = default;
      ~atomic() noexcept = default;
      atomic(const atomic&) = delete;
      atomic& operator=(const atomic&) = delete;
      atomic& operator=(const atomic&) volatile = delete;

      constexpr atomic(__integral_type __i) noexcept : __base_type(__i) { }

      using __base_type::operator __integral_type;
      using __base_type::operator=;
    };

  /// Explicit specialization for unsigned int.
  template<>
    struct atomic<unsigned int> : public atomic_uint
    {
      typedef unsigned int      __integral_type;
      typedef atomic_uint       __base_type;

      atomic() noexcept = default;
      ~atomic() noexcept = default;
      atomic(const atomic&) = delete;
      atomic& operator=(const atomic&) = delete;
      atomic& operator=(const atomic&) volatile = delete;

      constexpr atomic(__integral_type __i) noexcept : __base_type(__i) { }

      using __base_type::operator __integral_type;
      using __base_type::operator=;
    };

  /// Explicit specialization for long.
  template<>
    struct atomic<long> : public atomic_long
    {
      typedef long          __integral_type;
      typedef atomic_long       __base_type;

      atomic() noexcept = default;
      ~atomic() noexcept = default;
      atomic(const atomic&) = delete;
      atomic& operator=(const atomic&) = delete;
      atomic& operator=(const atomic&) volatile = delete;

      constexpr atomic(__integral_type __i) noexcept : __base_type(__i) { }

      using __base_type::operator __integral_type;
      using __base_type::operator=;
    };

  /// Explicit specialization for unsigned long.
  template<>
    struct atomic<unsigned long> : public atomic_ulong
    {
      typedef unsigned long         __integral_type;
      typedef atomic_ulong      __base_type;

      atomic() noexcept = default;
      ~atomic() noexcept = default;
      atomic(const atomic&) = delete;
      atomic& operator=(const atomic&) = delete;
      atomic& operator=(const atomic&) volatile = delete;

      constexpr atomic(__integral_type __i) noexcept : __base_type(__i) { }

      using __base_type::operator __integral_type;
      using __base_type::operator=;
    };

  /// Explicit specialization for long long.
  template<>
    struct atomic<long long> : public atomic_llong
    {
      typedef long long         __integral_type;
      typedef atomic_llong      __base_type;

      atomic() noexcept = default;
      ~atomic() noexcept = default;
      atomic(const atomic&) = delete;
      atomic& operator=(const atomic&) = delete;
      atomic& operator=(const atomic&) volatile = delete;

      constexpr atomic(__integral_type __i) noexcept : __base_type(__i) { }

      using __base_type::operator __integral_type;
      using __base_type::operator=;
    };

  /// Explicit specialization for unsigned long long.
  template<>
    struct atomic<unsigned long long> : public atomic_ullong
    {
      typedef unsigned long long        __integral_type;
      typedef atomic_ullong         __base_type;

      atomic() noexcept = default;
      ~atomic() noexcept = default;
      atomic(const atomic&) = delete;
      atomic& operator=(const atomic&) = delete;
      atomic& operator=(const atomic&) volatile = delete;

      constexpr atomic(__integral_type __i) noexcept : __base_type(__i) { }

      using __base_type::operator __integral_type;
      using __base_type::operator=;
    };

  /// Explicit specialization for wchar_t.
  template<>
    struct atomic<wchar_t> : public atomic_wchar_t
    {
      typedef wchar_t           __integral_type;
      typedef atomic_wchar_t        __base_type;

      atomic() noexcept = default;
      ~atomic() noexcept = default;
      atomic(const atomic&) = delete;
      atomic& operator=(const atomic&) = delete;
      atomic& operator=(const atomic&) volatile = delete;

      constexpr atomic(__integral_type __i) noexcept : __base_type(__i) { }

      using __base_type::operator __integral_type;
      using __base_type::operator=;
    };

  /// Explicit specialization for char16_t.
  template<>
    struct atomic<char16_t> : public atomic_char16_t
    {
      typedef char16_t          __integral_type;
      typedef atomic_char16_t       __base_type;

      atomic() noexcept = default;
      ~atomic() noexcept = default;
      atomic(const atomic&) = delete;
      atomic& operator=(const atomic&) = delete;
      atomic& operator=(const atomic&) volatile = delete;

      constexpr atomic(__integral_type __i) noexcept : __base_type(__i) { }

      using __base_type::operator __integral_type;
      using __base_type::operator=;
    };

  /// Explicit specialization for char32_t.
  template<>
    struct atomic<char32_t> : public atomic_char32_t
    {
      typedef char32_t          __integral_type;
      typedef atomic_char32_t       __base_type;

      atomic() noexcept = default;
      ~atomic() noexcept = default;
      atomic(const atomic&) = delete;
      atomic& operator=(const atomic&) = delete;
      atomic& operator=(const atomic&) volatile = delete;

      constexpr atomic(__integral_type __i) noexcept : __base_type(__i) { }

      using __base_type::operator __integral_type;
      using __base_type::operator=;
    };


  // Function definitions, atomic_flag operations.
  inline bool
  atomic_flag_test_and_set_explicit(atomic_flag* __a,
                    memory_order __m) noexcept
  { return __a->test_and_set(__m); }

  inline bool
  atomic_flag_test_and_set_explicit(volatile atomic_flag* __a,
                    memory_order __m) noexcept
  { return __a->test_and_set(__m); }

  inline void
  atomic_flag_clear_explicit(atomic_flag* __a, memory_order __m) noexcept
  { __a->clear(__m); }

  inline void
  atomic_flag_clear_explicit(volatile atomic_flag* __a,
                 memory_order __m) noexcept
  { __a->clear(__m); }

  inline bool
  atomic_flag_test_and_set(atomic_flag* __a) noexcept
  { return atomic_flag_test_and_set_explicit(__a, memory_order_seq_cst); }

  inline bool
  atomic_flag_test_and_set(volatile atomic_flag* __a) noexcept
  { return atomic_flag_test_and_set_explicit(__a, memory_order_seq_cst); }

  inline void
  atomic_flag_clear(atomic_flag* __a) noexcept
  { atomic_flag_clear_explicit(__a, memory_order_seq_cst); }

  inline void
  atomic_flag_clear(volatile atomic_flag* __a) noexcept
  { atomic_flag_clear_explicit(__a, memory_order_seq_cst); }


  // Function templates generally applicable to atomic types.
  template<typename _ITp>
    inline bool
    atomic_is_lock_free(const atomic<_ITp>* __a) noexcept
    { return __a->is_lock_free(); }

  template<typename _ITp>
    inline bool
    atomic_is_lock_free(const volatile atomic<_ITp>* __a) noexcept
    { return __a->is_lock_free(); }

  template<typename _ITp>
    inline void
    atomic_init(atomic<_ITp>* __a, _ITp __i) noexcept;

  template<typename _ITp>
    inline void
    atomic_init(volatile atomic<_ITp>* __a, _ITp __i) noexcept;

  template<typename _ITp>
    inline void
    atomic_store_explicit(atomic<_ITp>* __a, _ITp __i,
              memory_order __m) noexcept
    { __a->store(__i, __m); }

  template<typename _ITp>
    inline void
    atomic_store_explicit(volatile atomic<_ITp>* __a, _ITp __i,
              memory_order __m) noexcept
    { __a->store(__i, __m); }

  template<typename _ITp>
    inline _ITp
    atomic_load_explicit(const atomic<_ITp>* __a, memory_order __m) noexcept
    { return __a->load(__m); }

  template<typename _ITp>
    inline _ITp
    atomic_load_explicit(const volatile atomic<_ITp>* __a,
             memory_order __m) noexcept
    { return __a->load(__m); }

  template<typename _ITp>
    inline _ITp
    atomic_exchange_explicit(atomic<_ITp>* __a, _ITp __i,
                 memory_order __m) noexcept
    { return __a->exchange(__i, __m); }

  template<typename _ITp>
    inline _ITp
    atomic_exchange_explicit(volatile atomic<_ITp>* __a, _ITp __i,
                 memory_order __m) noexcept
    { return __a->exchange(__i, __m); }

  template<typename _ITp>
    inline bool
    atomic_compare_exchange_weak_explicit(atomic<_ITp>* __a,
                      _ITp* __i1, _ITp __i2,
                      memory_order __m1,
                      memory_order __m2) noexcept
    { return __a->compare_exchange_weak(*__i1, __i2, __m1, __m2); }

  template<typename _ITp>
    inline bool
    atomic_compare_exchange_weak_explicit(volatile atomic<_ITp>* __a,
                      _ITp* __i1, _ITp __i2,
                      memory_order __m1,
                      memory_order __m2) noexcept
    { return __a->compare_exchange_weak(*__i1, __i2, __m1, __m2); }

  template<typename _ITp>
    inline bool
    atomic_compare_exchange_strong_explicit(atomic<_ITp>* __a,
                        _ITp* __i1, _ITp __i2,
                        memory_order __m1,
                        memory_order __m2) noexcept
    { return __a->compare_exchange_strong(*__i1, __i2, __m1, __m2); }

  template<typename _ITp>
    inline bool
    atomic_compare_exchange_strong_explicit(volatile atomic<_ITp>* __a,
                        _ITp* __i1, _ITp __i2,
                        memory_order __m1,
                        memory_order __m2) noexcept
    { return __a->compare_exchange_strong(*__i1, __i2, __m1, __m2); }


  template<typename _ITp>
    inline void
    atomic_store(atomic<_ITp>* __a, _ITp __i) noexcept
    { atomic_store_explicit(__a, __i, memory_order_seq_cst); }

  template<typename _ITp>
    inline void
    atomic_store(volatile atomic<_ITp>* __a, _ITp __i) noexcept
    { atomic_store_explicit(__a, __i, memory_order_seq_cst); }

  template<typename _ITp>
    inline _ITp
    atomic_load(const atomic<_ITp>* __a) noexcept
    { return atomic_load_explicit(__a, memory_order_seq_cst); }

  template<typename _ITp>
    inline _ITp
    atomic_load(const volatile atomic<_ITp>* __a) noexcept
    { return atomic_load_explicit(__a, memory_order_seq_cst); }

  template<typename _ITp>
    inline _ITp
    atomic_exchange(atomic<_ITp>* __a, _ITp __i) noexcept
    { return atomic_exchange_explicit(__a, __i, memory_order_seq_cst); }

  template<typename _ITp>
    inline _ITp
    atomic_exchange(volatile atomic<_ITp>* __a, _ITp __i) noexcept
    { return atomic_exchange_explicit(__a, __i, memory_order_seq_cst); }

  template<typename _ITp>
    inline bool
    atomic_compare_exchange_weak(atomic<_ITp>* __a,
                 _ITp* __i1, _ITp __i2) noexcept
    {
      return atomic_compare_exchange_weak_explicit(__a, __i1, __i2,
                           memory_order_seq_cst,
                           memory_order_seq_cst);
    }

  template<typename _ITp>
    inline bool
    atomic_compare_exchange_weak(volatile atomic<_ITp>* __a,
                 _ITp* __i1, _ITp __i2) noexcept
    {
      return atomic_compare_exchange_weak_explicit(__a, __i1, __i2,
                           memory_order_seq_cst,
                           memory_order_seq_cst);
    }

  template<typename _ITp>
    inline bool
    atomic_compare_exchange_strong(atomic<_ITp>* __a,
                   _ITp* __i1, _ITp __i2) noexcept
    {
      return atomic_compare_exchange_strong_explicit(__a, __i1, __i2,
                             memory_order_seq_cst,
                             memory_order_seq_cst);
    }

  template<typename _ITp>
    inline bool
    atomic_compare_exchange_strong(volatile atomic<_ITp>* __a,
                   _ITp* __i1, _ITp __i2) noexcept
    {
      return atomic_compare_exchange_strong_explicit(__a, __i1, __i2,
                             memory_order_seq_cst,
                             memory_order_seq_cst);
    }

  // Function templates for atomic_integral operations only, using
  // __atomic_base. Template argument should be constricted to
  // intergral types as specified in the standard, excluding address
  // types.
  template<typename _ITp>
    inline _ITp
    atomic_fetch_add_explicit(__atomic_base<_ITp>* __a, _ITp __i,
                  memory_order __m) noexcept
    { return __a->fetch_add(__i, __m); }

  template<typename _ITp>
    inline _ITp
    atomic_fetch_add_explicit(volatile __atomic_base<_ITp>* __a, _ITp __i,
                  memory_order __m) noexcept
    { return __a->fetch_add(__i, __m); }

  template<typename _ITp>
    inline _ITp
    atomic_fetch_sub_explicit(__atomic_base<_ITp>* __a, _ITp __i,
                  memory_order __m) noexcept
    { return __a->fetch_sub(__i, __m); }

  template<typename _ITp>
    inline _ITp
    atomic_fetch_sub_explicit(volatile __atomic_base<_ITp>* __a, _ITp __i,
                  memory_order __m) noexcept
    { return __a->fetch_sub(__i, __m); }

  template<typename _ITp>
    inline _ITp
    atomic_fetch_and_explicit(__atomic_base<_ITp>* __a, _ITp __i,
                  memory_order __m) noexcept
    { return __a->fetch_and(__i, __m); }

  template<typename _ITp>
    inline _ITp
    atomic_fetch_and_explicit(volatile __atomic_base<_ITp>* __a, _ITp __i,
                  memory_order __m) noexcept
    { return __a->fetch_and(__i, __m); }

  template<typename _ITp>
    inline _ITp
    atomic_fetch_or_explicit(__atomic_base<_ITp>* __a, _ITp __i,
                 memory_order __m) noexcept
    { return __a->fetch_or(__i, __m); }

  template<typename _ITp>
    inline _ITp
    atomic_fetch_or_explicit(volatile __atomic_base<_ITp>* __a, _ITp __i,
                 memory_order __m) noexcept
    { return __a->fetch_or(__i, __m); }

  template<typename _ITp>
    inline _ITp
    atomic_fetch_xor_explicit(__atomic_base<_ITp>* __a, _ITp __i,
                  memory_order __m) noexcept
    { return __a->fetch_xor(__i, __m); }

  template<typename _ITp>
    inline _ITp
    atomic_fetch_xor_explicit(volatile __atomic_base<_ITp>* __a, _ITp __i,
                  memory_order __m) noexcept
    { return __a->fetch_xor(__i, __m); }

  template<typename _ITp>
    inline _ITp
    atomic_fetch_add(__atomic_base<_ITp>* __a, _ITp __i) noexcept
    { return atomic_fetch_add_explicit(__a, __i, memory_order_seq_cst); }

  template<typename _ITp>
    inline _ITp
    atomic_fetch_add(volatile __atomic_base<_ITp>* __a, _ITp __i) noexcept
    { return atomic_fetch_add_explicit(__a, __i, memory_order_seq_cst); }

  template<typename _ITp>
    inline _ITp
    atomic_fetch_sub(__atomic_base<_ITp>* __a, _ITp __i) noexcept
    { return atomic_fetch_sub_explicit(__a, __i, memory_order_seq_cst); }

  template<typename _ITp>
    inline _ITp
    atomic_fetch_sub(volatile __atomic_base<_ITp>* __a, _ITp __i) noexcept
    { return atomic_fetch_sub_explicit(__a, __i, memory_order_seq_cst); }

  template<typename _ITp>
    inline _ITp
    atomic_fetch_and(__atomic_base<_ITp>* __a, _ITp __i) noexcept
    { return atomic_fetch_and_explicit(__a, __i, memory_order_seq_cst); }

  template<typename _ITp>
    inline _ITp
    atomic_fetch_and(volatile __atomic_base<_ITp>* __a, _ITp __i) noexcept
    { return atomic_fetch_and_explicit(__a, __i, memory_order_seq_cst); }

  template<typename _ITp>
    inline _ITp
    atomic_fetch_or(__atomic_base<_ITp>* __a, _ITp __i) noexcept
    { return atomic_fetch_or_explicit(__a, __i, memory_order_seq_cst); }

  template<typename _ITp>
    inline _ITp
    atomic_fetch_or(volatile __atomic_base<_ITp>* __a, _ITp __i) noexcept
    { return atomic_fetch_or_explicit(__a, __i, memory_order_seq_cst); }

  template<typename _ITp>
    inline _ITp
    atomic_fetch_xor(__atomic_base<_ITp>* __a, _ITp __i) noexcept
    { return atomic_fetch_xor_explicit(__a, __i, memory_order_seq_cst); }

  template<typename _ITp>
    inline _ITp
    atomic_fetch_xor(volatile __atomic_base<_ITp>* __a, _ITp __i) noexcept
    { return atomic_fetch_xor_explicit(__a, __i, memory_order_seq_cst); }


  // Partial specializations for pointers.
  template<typename _ITp>
    inline _ITp*
    atomic_fetch_add_explicit(atomic<_ITp*>* __a, ptrdiff_t __d,
                  memory_order __m) noexcept
    { return __a->fetch_add(__d, __m); }

  template<typename _ITp>
    inline _ITp*
    atomic_fetch_add_explicit(volatile atomic<_ITp*>* __a, ptrdiff_t __d,
                  memory_order __m) noexcept
    { return __a->fetch_add(__d, __m); }

  template<typename _ITp>
    inline _ITp*
    atomic_fetch_add(volatile atomic<_ITp*>* __a, ptrdiff_t __d) noexcept
    { return __a->fetch_add(__d); }

  template<typename _ITp>
    inline _ITp*
    atomic_fetch_add(atomic<_ITp*>* __a, ptrdiff_t __d) noexcept
    { return __a->fetch_add(__d); }

  template<typename _ITp>
    inline _ITp*
    atomic_fetch_sub_explicit(volatile atomic<_ITp*>* __a,
                  ptrdiff_t __d, memory_order __m) noexcept
    { return __a->fetch_sub(__d, __m); }

  template<typename _ITp>
    inline _ITp*
    atomic_fetch_sub_explicit(atomic<_ITp*>* __a, ptrdiff_t __d,
                  memory_order __m) noexcept
    { return __a->fetch_sub(__d, __m); }

  template<typename _ITp>
    inline _ITp*
    atomic_fetch_sub(volatile atomic<_ITp*>* __a, ptrdiff_t __d) noexcept
    { return __a->fetch_sub(__d); }

  template<typename _ITp>
    inline _ITp*
    atomic_fetch_sub(atomic<_ITp*>* __a, ptrdiff_t __d) noexcept
    { return __a->fetch_sub(__d); }
  // @} group atomics

_GLIBCXX_END_NAMESPACE_VERSION
} // namespace

#endif