// Support for atomic operations -*- C++ -*-

// Copyright (C) 2004-2020 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 ext/atomicity.h
 *  This file is a GNU extension to the Standard C++ Library.
 */

#ifndef _GLIBCXX_ATOMICITY_H
#define _GLIBCXX_ATOMICITY_H 1

#pragma GCC system_header

#include <bits/c++config.h>
#include <bits/gthr.h>
#include <bits/atomic_word.h>

namespace __gnu_cxx _GLIBCXX_VISIBILITY(default)
{
    _GLIBCXX_BEGIN_NAMESPACE_VERSION

    // Functions for portable atomic access.
    // To abstract locking primitives across all thread policies, use:
    // __exchange_and_add_dispatch
    // __atomic_add_dispatch
#ifdef _GLIBCXX_ATOMIC_BUILTINS
    static inline _Atomic_word __attribute__((__always_inline__))
    __exchange_and_add(volatile _Atomic_word * __mem, int __val)
    {
        return __atomic_add_fetch(__mem, __val, __ATOMIC_ACQ_REL);
    }

    static inline void __attribute__((__always_inline__)) __atomic_add(volatile _Atomic_word * __mem, int __val)
    {
        __atomic_add_fetch(__mem, __val, __ATOMIC_ACQ_REL);
    }
#else
    _Atomic_word __exchange_and_add(volatile _Atomic_word *, int) _GLIBCXX_NOTHROW;

    void __atomic_add(volatile _Atomic_word *, int) _GLIBCXX_NOTHROW;
#endif

    static inline _Atomic_word __attribute__((__always_inline__))
    __exchange_and_add_single(_Atomic_word * __mem, int __val)
    {
        return __atomic_add_fetch(__mem, __val, __ATOMIC_ACQ_REL);
    }

    static inline void __attribute__((__always_inline__)) __atomic_add_single(_Atomic_word * __mem, int __val)
    {
        __atomic_add_fetch(__mem, __val, __ATOMIC_ACQ_REL);
    }

    static inline _Atomic_word __attribute__((__always_inline__))
    __exchange_and_add_dispatch(_Atomic_word * __mem, int __val)
    {
        return __exchange_and_add_single(__mem, __val);
    }

    static inline void __attribute__((__always_inline__)) __atomic_add_dispatch(_Atomic_word * __mem, int __val)
    {
        __atomic_add_single(__mem, __val);
    }

    _GLIBCXX_END_NAMESPACE_VERSION
} // namespace )

// Even if the CPU doesn't need a memory barrier, we need to ensure
// that the compiler doesn't reorder memory accesses across the
// barriers.
#ifndef _GLIBCXX_READ_MEM_BARRIER
#define _GLIBCXX_READ_MEM_BARRIER __atomic_thread_fence(__ATOMIC_ACQUIRE)
#endif
#ifndef _GLIBCXX_WRITE_MEM_BARRIER
#define _GLIBCXX_WRITE_MEM_BARRIER __atomic_thread_fence(__ATOMIC_RELEASE)
#endif

#endif