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Filename : fp_ops_emulated.hpp
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/*
 * Distributed under the Boost Software License, Version 1.0.
 * (See accompanying file LICENSE_1_0.txt or copy at
 * http://www.boost.org/LICENSE_1_0.txt)
 *
 * Copyright (c) 2018 Andrey Semashev
 */
/*!
 * \file   atomic/detail/fp_ops_emulated.hpp
 *
 * This header contains emulated (lock-based) implementation of the floating point atomic operations.
 */

#ifndef BOOST_ATOMIC_DETAIL_FP_OPS_EMULATED_HPP_INCLUDED_
#define BOOST_ATOMIC_DETAIL_FP_OPS_EMULATED_HPP_INCLUDED_

#include <cstddef>
#include <boost/static_assert.hpp>
#include <boost/memory_order.hpp>
#include <boost/atomic/detail/config.hpp>
#include <boost/atomic/detail/bitwise_fp_cast.hpp>
#include <boost/atomic/detail/fp_operations_fwd.hpp>
#include <boost/atomic/detail/header.hpp>

#ifdef BOOST_HAS_PRAGMA_ONCE
#pragma once
#endif

namespace boost {
namespace atomics {
namespace detail {

//! Emulated implementation of floating point operations
template< typename Base, typename Value, std::size_t Size >
struct fp_operations_emulated :
    public Base
{
    typedef Base base_type;
    typedef typename base_type::storage_type storage_type;
    typedef Value value_type;
    typedef typename base_type::scoped_lock scoped_lock;

    static value_type fetch_add(storage_type volatile& storage, value_type v, memory_order) BOOST_NOEXCEPT
    {
        BOOST_STATIC_ASSERT_MSG(!base_type::is_interprocess, "Boost.Atomic: operation invoked on a non-lock-free inter-process atomic object");
        storage_type& s = const_cast< storage_type& >(storage);
        scoped_lock lock(&storage);
        value_type old_val = atomics::detail::bitwise_fp_cast< value_type >(s);
        value_type new_val = old_val + v;
        s = atomics::detail::bitwise_fp_cast< storage_type >(new_val);
        return old_val;
    }

    static value_type fetch_sub(storage_type volatile& storage, value_type v, memory_order) BOOST_NOEXCEPT
    {
        BOOST_STATIC_ASSERT_MSG(!base_type::is_interprocess, "Boost.Atomic: operation invoked on a non-lock-free inter-process atomic object");
        storage_type& s = const_cast< storage_type& >(storage);
        scoped_lock lock(&storage);
        value_type old_val = atomics::detail::bitwise_fp_cast< value_type >(s);
        value_type new_val = old_val - v;
        s = atomics::detail::bitwise_fp_cast< storage_type >(new_val);
        return old_val;
    }
};

template< typename Base, typename Value, std::size_t Size >
struct fp_operations< Base, Value, Size, false > :
    public fp_operations_emulated< Base, Value, Size >
{
};

} // namespace detail
} // namespace atomics
} // namespace boost

#include <boost/atomic/detail/footer.hpp>

#endif // BOOST_ATOMIC_DETAIL_FP_OPS_EMULATED_HPP_INCLUDED_