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1/*
2 * Distributed under the Boost Software License, Version 1.0.
3 * (See accompanying file LICENSE_1_0.txt or copy at
4 * http://www.boost.org/LICENSE_1_0.txt)
5 *
6 * Copyright (c) 2014 Andrey Semashev
7 */
8/*!
9 * \file atomic/detail/ops_extending_cas_based.hpp
10 *
11 * This header contains a boilerplate of the \c operations template implementation that requires sign/zero extension in arithmetic operations.
12 */
13
14#ifndef BOOST_ATOMIC_DETAIL_OPS_EXTENDING_CAS_BASED_HPP_INCLUDED_
15#define BOOST_ATOMIC_DETAIL_OPS_EXTENDING_CAS_BASED_HPP_INCLUDED_
16
17#include <cstddef>
18#include <boost/memory_order.hpp>
19#include <boost/atomic/detail/config.hpp>
20#include <boost/atomic/detail/storage_type.hpp>
21
22#ifdef BOOST_HAS_PRAGMA_ONCE
23#pragma once
24#endif
25
26namespace boost {
27namespace atomics {
28namespace detail {
29
30template< typename Base, std::size_t Size, bool Signed >
31struct extending_cas_based_operations :
32 public Base
33{
34 typedef typename Base::storage_type storage_type;
35 typedef typename make_storage_type< Size, Signed >::type emulated_storage_type;
36
37 static BOOST_FORCEINLINE storage_type fetch_add(storage_type volatile& storage, storage_type v, memory_order order) BOOST_NOEXCEPT
38 {
39 storage_type old_val;
40 atomics::detail::non_atomic_load(storage, old_val);
41 emulated_storage_type new_val;
42 do
43 {
44 new_val = static_cast< emulated_storage_type >(old_val) + static_cast< emulated_storage_type >(v);
45 }
46 while (!Base::compare_exchange_weak(storage, old_val, static_cast< storage_type >(new_val), order, memory_order_relaxed));
47 return old_val;
48 }
49
50 static BOOST_FORCEINLINE storage_type fetch_sub(storage_type volatile& storage, storage_type v, memory_order order) BOOST_NOEXCEPT
51 {
52 storage_type old_val;
53 atomics::detail::non_atomic_load(storage, old_val);
54 emulated_storage_type new_val;
55 do
56 {
57 new_val = static_cast< emulated_storage_type >(old_val) - static_cast< emulated_storage_type >(v);
58 }
59 while (!Base::compare_exchange_weak(storage, old_val, static_cast< storage_type >(new_val), order, memory_order_relaxed));
60 return old_val;
61 }
62};
63
64} // namespace detail
65} // namespace atomics
66} // namespace boost
67
68#endif // BOOST_ATOMIC_DETAIL_OPS_EXTENDING_CAS_BASED_HPP_INCLUDED_