75 lines
2.1 KiB
C++
75 lines
2.1 KiB
C++
/*
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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) 2009 Helge Bahmann
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* Copyright (c) 2012 Tim Blechmann
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* Copyright (c) 2013 - 2014 Andrey Semashev
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*/
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/*!
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* \file atomic/detail/bitwise_cast.hpp
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*
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* This header defines \c bitwise_cast used to convert between storage and value types
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*/
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#ifndef BOOST_ATOMIC_DETAIL_BITWISE_CAST_HPP_INCLUDED_
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#define BOOST_ATOMIC_DETAIL_BITWISE_CAST_HPP_INCLUDED_
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#include <boost/atomic/detail/config.hpp>
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#if !defined(BOOST_ATOMIC_DETAIL_HAS_BUILTIN_MEMCPY)
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#include <cstring>
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#endif
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#ifdef BOOST_HAS_PRAGMA_ONCE
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#pragma once
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#endif
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#if defined(BOOST_GCC) && (BOOST_GCC+0) >= 40600
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#pragma GCC diagnostic push
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// missing initializer for member var
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#pragma GCC diagnostic ignored "-Wmissing-field-initializers"
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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 T >
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BOOST_FORCEINLINE T* addressof(T& value) BOOST_NOEXCEPT
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{
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// Note: The point of using a local struct as the intermediate type instead of char is to avoid gcc warnings
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// if T is a const volatile char*:
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// warning: casting 'const volatile char* const' to 'const volatile char&' does not dereference pointer
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// The local struct makes sure T is not related to the cast target type.
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struct opaque_type;
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return reinterpret_cast< T* >(&const_cast< opaque_type& >(reinterpret_cast< const volatile opaque_type& >(value)));
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}
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template< typename To, typename From >
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BOOST_FORCEINLINE To bitwise_cast(From const& from) BOOST_NOEXCEPT
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{
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struct
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{
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To to;
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}
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value = {};
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BOOST_ATOMIC_DETAIL_MEMCPY
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(
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atomics::detail::addressof(value.to),
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atomics::detail::addressof(from),
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(sizeof(From) < sizeof(To) ? sizeof(From) : sizeof(To))
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);
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return value.to;
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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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#if defined(BOOST_GCC) && (BOOST_GCC+0) >= 40600
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#pragma GCC diagnostic pop
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#endif
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#endif // BOOST_ATOMIC_DETAIL_BITWISE_CAST_HPP_INCLUDED_
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