| /* |
| * 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) 2009 Helge Bahmann |
| * Copyright (c) 2012 Tim Blechmann |
| * Copyright (c) 2013 - 2018, 2020 Andrey Semashev |
| */ |
| /*! |
| * \file atomic/detail/bitwise_cast.hpp |
| * |
| * This header defines \c bitwise_cast used to convert between storage and value types |
| */ |
| |
| #ifndef BOOST_ATOMIC_DETAIL_BITWISE_CAST_HPP_INCLUDED_ |
| #define BOOST_ATOMIC_DETAIL_BITWISE_CAST_HPP_INCLUDED_ |
| |
| #include <cstddef> |
| #include <boost/atomic/detail/config.hpp> |
| #include <boost/atomic/detail/addressof.hpp> |
| #include <boost/atomic/detail/string_ops.hpp> |
| #include <boost/atomic/detail/type_traits/integral_constant.hpp> |
| #include <boost/atomic/detail/header.hpp> |
| |
| #ifdef BOOST_HAS_PRAGMA_ONCE |
| #pragma once |
| #endif |
| |
| #if defined(BOOST_GCC) && BOOST_GCC >= 80000 |
| #pragma GCC diagnostic push |
| // copying an object of non-trivial type X from an array of Y. This is benign because we use memcpy to copy trivially copyable objects. |
| #pragma GCC diagnostic ignored "-Wclass-memaccess" |
| #endif |
| |
| namespace boost { |
| namespace atomics { |
| namespace detail { |
| |
| template< std::size_t FromSize, typename To > |
| BOOST_FORCEINLINE void clear_tail_padding_bits(To& to, atomics::detail::true_type) BOOST_NOEXCEPT |
| { |
| BOOST_ATOMIC_DETAIL_MEMSET(reinterpret_cast< unsigned char* >(atomics::detail::addressof(to)) + FromSize, 0, sizeof(To) - FromSize); |
| } |
| |
| template< std::size_t FromSize, typename To > |
| BOOST_FORCEINLINE void clear_tail_padding_bits(To&, atomics::detail::false_type) BOOST_NOEXCEPT |
| { |
| } |
| |
| template< std::size_t FromSize, typename To > |
| BOOST_FORCEINLINE void clear_tail_padding_bits(To& to) BOOST_NOEXCEPT |
| { |
| atomics::detail::clear_tail_padding_bits< FromSize >(to, atomics::detail::integral_constant< bool, FromSize < sizeof(To) >()); |
| } |
| |
| template< typename To, std::size_t FromSize, typename From > |
| BOOST_FORCEINLINE To bitwise_cast(From const& from) BOOST_NOEXCEPT |
| { |
| To to; |
| BOOST_ATOMIC_DETAIL_MEMCPY |
| ( |
| atomics::detail::addressof(to), |
| atomics::detail::addressof(from), |
| (FromSize < sizeof(To) ? FromSize : sizeof(To)) |
| ); |
| atomics::detail::clear_tail_padding_bits< FromSize >(to); |
| return to; |
| } |
| |
| template< typename To, typename From > |
| BOOST_FORCEINLINE To bitwise_cast(From const& from) BOOST_NOEXCEPT |
| { |
| return atomics::detail::bitwise_cast< To, sizeof(From) >(from); |
| } |
| |
| } // namespace detail |
| } // namespace atomics |
| } // namespace boost |
| |
| #if defined(BOOST_GCC) && BOOST_GCC >= 80000 |
| #pragma GCC diagnostic pop |
| #endif |
| |
| #include <boost/atomic/detail/footer.hpp> |
| |
| #endif // BOOST_ATOMIC_DETAIL_BITWISE_CAST_HPP_INCLUDED_ |