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

// Copyright (C) 2008, 2009
// 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 cstdatomic
 *  This is a Standard C++ Library file.  You should @c #include this file
 *  in your programs, rather than any of the "*.h" implementation files.
 *
 *  This is the C++ version of the Standard C Library header @c stdatomic.h,
 *  and its contents are (mostly) the same as that header, but are all
 *  contained in the namespace @c std (except for names which are defined
 *  as macros in C).
 */

// 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_STDATOMIC
#define _GLIBCXX_STDATOMIC 1

#pragma GCC system_header

#ifndef __GXX_EXPERIMENTAL_CXX0X__
# include <c++0x_warning.h>
#endif

#include <stdatomic.h>
#include <cstddef>

_GLIBCXX_BEGIN_NAMESPACE(std)

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

/// kill_dependency
  template<typename _Tp>
    inline _Tp 
    kill_dependency(_Tp __y)
    {
      _Tp ret(__y);
      return ret;
    }

inline memory_order
  __calculate_memory_order(memory_order __m)
  {
    const bool __cond1 = __m == memory_order_release;
    const bool __cond2 = __m == memory_order_acq_rel;
    memory_order __mo1(__cond1 ? memory_order_relaxed : __m);
    memory_order __mo2(__cond2 ? memory_order_acquire : __mo1);
    return __mo2;
  }

//
  // Three nested namespaces for atomic implementation details.
  // 
  // The nested namespace inlined into std:: is determined by the value
  // of the _GLIBCXX_ATOMIC_PROPERTY macro and the resulting
  // ATOMIC_*_LOCK_FREE macros. See file stdatomic.h.
  //
  // 0 == __atomic0 == Never lock-free
  // 1 == __atomic1 == Best available, sometimes lock-free
  // 2 == __atomic2 == Always lock-free
#include <bits/atomic_0.h>
#include <bits/atomic_2.h>

/// atomic
  /// 29.4.3, Generic atomic type, primary class template.
  template<typename _Tp>
    struct atomic
    {
    private:
      _Tp _M_i;

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

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

operator _Tp() const volatile;

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

bool 
      is_lock_free() const volatile;

void 
      store(_Tp, memory_order = memory_order_seq_cst) volatile;

_Tp 
      load(memory_order = memory_order_seq_cst) const volatile;

_Tp 
      exchange(_Tp __i, memory_order = memory_order_seq_cst) volatile;

bool 
      compare_exchange_weak(_Tp&, _Tp, memory_order, memory_order) volatile;

bool 
      compare_exchange_strong(_Tp&, _Tp, memory_order, memory_order) volatile;

bool 
      compare_exchange_weak(_Tp&, _Tp, 
			    memory_order = memory_order_seq_cst) volatile;

bool 
      compare_exchange_strong(_Tp&, _Tp, 
			      memory_order = memory_order_seq_cst) volatile;
    };

/// Partial specialization for pointer types.
  template<typename _Tp> 
    struct atomic<_Tp*> : atomic_address
    {
      atomic() = default;
      ~atomic() = default;
      atomic(const atomic&) = delete;
      atomic& operator=(const atomic&) = delete;

atomic(_Tp* __v) : atomic_address(__v) { }

void 
      store(_Tp*, memory_order = memory_order_seq_cst) volatile;

_Tp* 
      load(memory_order = memory_order_seq_cst) const volatile;

_Tp* 
      exchange(_Tp*, memory_order = memory_order_seq_cst) volatile;

bool 
      compare_exchange_weak(_Tp*&, _Tp*, memory_order, memory_order) volatile;

bool 
      compare_exchange_strong(_Tp*&, _Tp*, memory_order, memory_order) volatile;

bool 
      compare_exchange_weak(_Tp*&, _Tp*, 
			    memory_order = memory_order_seq_cst) volatile;

bool 
      compare_exchange_strong(_Tp*&, _Tp*, 
			      memory_order = memory_order_seq_cst) volatile;

_Tp* 
      fetch_add(ptrdiff_t, memory_order = memory_order_seq_cst) volatile;

_Tp* 
      fetch_sub(ptrdiff_t, memory_order = memory_order_seq_cst) volatile;

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

_Tp* 
      operator=(_Tp* __v) volatile 
      { 
	store(__v); 
	return __v; 
      }

_Tp* 
      operator++(int) volatile { return fetch_add(1); }

_Tp* 
      operator--(int) volatile { return fetch_sub(1); }

_Tp* 
      operator++() volatile { return fetch_add(1) + 1; }

_Tp* 
      operator--() volatile { return fetch_sub(1) - 1; }

_Tp* 
      operator+=(ptrdiff_t __d) volatile 
      { return fetch_add(__d) + __d; }

_Tp* 
      operator-=(ptrdiff_t __d) volatile 
      { return fetch_sub(__d) - __d; }
    };

/// Explicit specialization for void*
  template<> 
    struct atomic<void*> : public atomic_address
    {
      typedef void* 			__integral_type;
      typedef atomic_address 		__base_type;