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// -*- C++ -*-

// Copyright (C) 2007, 2008, 2009, 2010, 2012 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 parallel/compatibility.h

 *  @brief Compatibility layer, mostly concerned with atomic operations.

 *

 *  This file is a GNU parallel extension to the Standard C++ Library

 *  and contains implementation details for the library's internal use.

 */

// Written by Felix Putze.

#ifndef _GLIBCXX_PARALLEL_COMPATIBILITY_H

#define _GLIBCXX_PARALLEL_COMPATIBILITY_H 1

#include <parallel/types.h>

#include <parallel/base.h>

#if !defined(_WIN32) || defined (__CYGWIN__)

#include <sched.h>

#endif

#ifdef __MINGW32__

// Including <windows.h> will drag in all the windows32 names.  Since

// that can cause user code portability problems, we just declare the

// one needed function here.

extern "C"

__attribute((dllimport)) void __attribute__((stdcall)) Sleep (unsigned long);

#endif

namespace __gnu_parallel

{

  template<typename _Tp>

    inline _Tp

    __add_omp(volatile _Tp* __ptr, _Tp __addend)

    {

      int64_t __res;

#pragma omp critical

      {

        __res = *__ptr;

        *(__ptr) += __addend;

      }

      return __res;

    }

  /** @brief Add a value to a variable, atomically.

   *

   *  @param __ptr Pointer to a signed integer.

   *  @param __addend Value to add.

   */

  template<typename _Tp>

    inline _Tp

    __fetch_and_add(volatile _Tp* __ptr, _Tp __addend)

    {

      if (__atomic_always_lock_free(sizeof(_Tp), __ptr))

        return __atomic_fetch_add(__ptr, __addend, __ATOMIC_ACQ_REL);

      return __add_omp(__ptr, __addend);

    }

  template<typename _Tp>

    inline bool

    __cas_omp(volatile _Tp* __ptr, _Tp __comparand, _Tp __replacement)

    {

      bool __res = false;

#pragma omp critical

      {

        if (*__ptr == __comparand)

          {

            *__ptr = __replacement;

            __res = true;

          }

      }

      return __res;

    }

  /** @brief Compare-and-swap

   *

   * Compare @c *__ptr and @c __comparand. If equal, let @c

   * *__ptr=__replacement and return @c true, return @c false otherwise.

   *

   *  @param __ptr Pointer to signed integer.

   *  @param __comparand Compare value.

   *  @param __replacement Replacement value.

   */

  template<typename _Tp>

    inline bool

    __compare_and_swap(volatile _Tp* __ptr, _Tp __comparand, _Tp __replacement)

    {

      if (__atomic_always_lock_free(sizeof(_Tp), __ptr))

        return __atomic_compare_exchange_n(__ptr, &__comparand, __replacement,

                                           false, __ATOMIC_ACQ_REL,

                                           __ATOMIC_RELAXED);

      return __cas_omp(__ptr, __comparand, __replacement);

    }

  /** @brief Yield control to another thread, without waiting for

   *  the end of the time slice.

   */

  inline void

  __yield()

  {

#if defined (_WIN32) && !defined (__CYGWIN__)

    Sleep(0);

#else

    sched_yield();

#endif

  }

} // end namespace

#endif /* _GLIBCXX_PARALLEL_COMPATIBILITY_H */