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) 2020 Andrey Semashev 7 */ 8 /*! 9 * \file atomic/detail/memory_order_utils.hpp 10 * 11 * This header contains utilities related to memory order constants. 12 */ 13 14 #ifndef BOOST_ATOMIC_DETAIL_MEMORY_ORDER_UTILS_HPP_INCLUDED_ 15 #define BOOST_ATOMIC_DETAIL_MEMORY_ORDER_UTILS_HPP_INCLUDED_ 16 17 #include <boost/memory_order.hpp> 18 #include <boost/atomic/detail/config.hpp> 19 #include <boost/atomic/detail/header.hpp> 20 21 #ifdef BOOST_HAS_PRAGMA_ONCE 22 #pragma once 23 #endif 24 25 namespace boost { 26 namespace atomics { 27 namespace detail { 28 deduce_failure_order(memory_order order)29BOOST_FORCEINLINE BOOST_CONSTEXPR memory_order deduce_failure_order(memory_order order) BOOST_NOEXCEPT 30 { 31 return order == memory_order_acq_rel ? memory_order_acquire : (order == memory_order_release ? memory_order_relaxed : order); 32 } 33 cas_failure_order_must_not_be_stronger_than_success_order(memory_order success_order,memory_order failure_order)34BOOST_FORCEINLINE BOOST_CONSTEXPR bool cas_failure_order_must_not_be_stronger_than_success_order(memory_order success_order, memory_order failure_order) BOOST_NOEXCEPT 35 { 36 // 15 == (memory_order_seq_cst | memory_order_consume), see memory_order.hpp 37 // Given the enum values we can test the strength of memory order requirements with this single condition. 38 return (static_cast< unsigned int >(failure_order) & 15u) <= (static_cast< unsigned int >(success_order) & 15u); 39 } 40 41 } // namespace detail 42 } // namespace atomics 43 } // namespace boost 44 45 #include <boost/atomic/detail/footer.hpp> 46 47 #endif // BOOST_ATOMIC_DETAIL_MEMORY_ORDER_UTILS_HPP_INCLUDED_ 48