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/*
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 * Distributed under the Boost Software License, Version 1.0.
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 * (See accompanying file LICENSE_1_0.txt or copy at
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 * http://www.boost.org/LICENSE_1_0.txt)
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 *
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 * Copyright (c) 2014 Andrey Semashev
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 */
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/*!
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 * \file   atomic/detail/ops_extending_cas_based.hpp
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 *
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 * This header contains a boilerplate of the \c operations template implementation that requires sign/zero extension in arithmetic operations.
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 */
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#ifndef BOOST_ATOMIC_DETAIL_OPS_EXTENDING_CAS_BASED_HPP_INCLUDED_
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#define BOOST_ATOMIC_DETAIL_OPS_EXTENDING_CAS_BASED_HPP_INCLUDED_
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#include <cstddef>
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#include <boost/memory_order.hpp>
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#include <boost/atomic/detail/config.hpp>
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#include <boost/atomic/detail/storage_type.hpp>
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#ifdef BOOST_HAS_PRAGMA_ONCE
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#pragma once
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#endif
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namespace boost {
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namespace atomics {
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namespace detail {
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template< typename Base, std::size_t Size, bool Signed >
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struct extending_cas_based_operations :
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    public Base
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{
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    typedef typename Base::storage_type storage_type;
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    typedef typename make_storage_type< Size, Signed >::type emulated_storage_type;
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    static BOOST_FORCEINLINE storage_type fetch_add(storage_type volatile& storage, storage_type v, memory_order order) BOOST_NOEXCEPT
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    {
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        storage_type old_val;
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        atomics::detail::non_atomic_load(storage, old_val);
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        emulated_storage_type new_val;
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        do
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        {
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            new_val = static_cast< emulated_storage_type >(old_val) + static_cast< emulated_storage_type >(v);
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        }
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        while (!Base::compare_exchange_weak(storage, old_val, static_cast< storage_type >(new_val), order, memory_order_relaxed));
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        return old_val;
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    }
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    static BOOST_FORCEINLINE storage_type fetch_sub(storage_type volatile& storage, storage_type v, memory_order order) BOOST_NOEXCEPT
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    {
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        storage_type old_val;
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        atomics::detail::non_atomic_load(storage, old_val);
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        emulated_storage_type new_val;
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        do
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        {
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            new_val = static_cast< emulated_storage_type >(old_val) - static_cast< emulated_storage_type >(v);
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        }
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        while (!Base::compare_exchange_weak(storage, old_val, static_cast< storage_type >(new_val), order, memory_order_relaxed));
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        return old_val;
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    }
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};
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} // namespace detail
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} // namespace atomics
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} // namespace boost
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#endif // BOOST_ATOMIC_DETAIL_OPS_EXTENDING_CAS_BASED_HPP_INCLUDED_