parallel/compatibility.h
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// -*- C++ -*-
// Copyright (C) 2007-2013 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 */