boost/atomic/detail/bitwise_cast.hpp
/*
* 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 - 2014 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 <boost/atomic/detail/config.hpp>
#if !defined(BOOST_ATOMIC_DETAIL_HAS_BUILTIN_MEMCPY)
#include <cstring>
#endif
#ifdef BOOST_HAS_PRAGMA_ONCE
#pragma once
#endif
#if defined(BOOST_GCC) && (BOOST_GCC+0) >= 40600
#pragma GCC diagnostic push
// missing initializer for member var
#pragma GCC diagnostic ignored "-Wmissing-field-initializers"
#endif
namespace boost {
namespace atomics {
namespace detail {
template< typename T >
BOOST_FORCEINLINE T* addressof(T& value) BOOST_NOEXCEPT
{
// Note: The point of using a local struct as the intermediate type instead of char is to avoid gcc warnings
// if T is a const volatile char*:
// warning: casting 'const volatile char* const' to 'const volatile char&' does not dereference pointer
// The local struct makes sure T is not related to the cast target type.
struct opaque_type;
return reinterpret_cast< T* >(&const_cast< opaque_type& >(reinterpret_cast< const volatile opaque_type& >(value)));
}
template< typename To, typename From >
BOOST_FORCEINLINE To bitwise_cast(From const& from) BOOST_NOEXCEPT
{
struct
{
To to;
}
value = {};
BOOST_ATOMIC_DETAIL_MEMCPY
(
atomics::detail::addressof(value.to),
atomics::detail::addressof(from),
(sizeof(From) < sizeof(To) ? sizeof(From) : sizeof(To))
);
return value.to;
}
} // namespace detail
} // namespace atomics
} // namespace boost
#if defined(BOOST_GCC) && (BOOST_GCC+0) >= 40600
#pragma GCC diagnostic pop
#endif
#endif // BOOST_ATOMIC_DETAIL_BITWISE_CAST_HPP_INCLUDED_