ceph/src/boost/boost/atomic/detail/bitwise_fp_cast.hpp

   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) 2018 Andrey Semashev
   7  */
   8 /*!
   9  * \file   atomic/detail/bitwise_fp_cast.hpp
  10  *
  11  * This header defines \c bitwise_fp_cast used to convert between storage and floating point value types
  12  */
  13
  14 #ifndef BOOST_ATOMIC_DETAIL_BITWISE_FP_CAST_HPP_INCLUDED_
  15 #define BOOST_ATOMIC_DETAIL_BITWISE_FP_CAST_HPP_INCLUDED_
  16
  17 #include <cstddef>
  18 #include <boost/atomic/detail/config.hpp>
  19 #include <boost/atomic/detail/float_sizes.hpp>
  20 #include <boost/atomic/detail/bitwise_cast.hpp>
  21 #include <boost/atomic/detail/header.hpp>
  22
  23 #ifdef BOOST_HAS_PRAGMA_ONCE
  24 #pragma once
  25 #endif
  26
  27 namespace boost {
  28 namespace atomics {
  29 namespace detail {
  30
  31 /*!
  32  * \brief The type trait returns the size of the value of the specified floating point type
  33  *
  34  * This size may be less than <tt>sizeof(T)</tt> if the implementation uses padding bytes for a particular FP type. This is
  35  * often the case with 80-bit extended double, which is stored in 12 or 16 bytes with padding filled with garbage.
  36  */
  37 template< typename T >
  38 struct value_sizeof
  39 {
  40     static BOOST_CONSTEXPR_OR_CONST std::size_t value = sizeof(T);
  41 };
  42
  43 #if defined(BOOST_ATOMIC_DETAIL_SIZEOF_FLOAT_VALUE)
  44 template< >
  45 struct value_sizeof< float >
  46 {
  47     static BOOST_CONSTEXPR_OR_CONST std::size_t value = BOOST_ATOMIC_DETAIL_SIZEOF_FLOAT_VALUE;
  48 };
  49 #endif
  50
  51 #if defined(BOOST_ATOMIC_DETAIL_SIZEOF_DOUBLE_VALUE)
  52 template< >
  53 struct value_sizeof< double >
  54 {
  55     static BOOST_CONSTEXPR_OR_CONST std::size_t value = BOOST_ATOMIC_DETAIL_SIZEOF_DOUBLE_VALUE;
  56 };
  57 #endif
  58
  59 #if defined(BOOST_ATOMIC_DETAIL_SIZEOF_LONG_DOUBLE_VALUE)
  60 template< >
  61 struct value_sizeof< long double >
  62 {
  63     static BOOST_CONSTEXPR_OR_CONST std::size_t value = BOOST_ATOMIC_DETAIL_SIZEOF_LONG_DOUBLE_VALUE;
  64 };
  65 #endif
  66
  67 template< typename T >
  68 struct value_sizeof< const T > : value_sizeof< T > {};
  69
  70 template< typename T >
  71 struct value_sizeof< volatile T > : value_sizeof< T > {};
  72
  73 template< typename T >
  74 struct value_sizeof< const volatile T > : value_sizeof< T > {};
  75
  76
  77 template< typename To, typename From >
  78 BOOST_FORCEINLINE To bitwise_fp_cast(From const& from) BOOST_NOEXCEPT
  79 {
  80     return atomics::detail::bitwise_cast< To, atomics::detail::value_sizeof< From >::value >(from);
  81 }
  82
  83 } // namespace detail
  84 } // namespace atomics
  85 } // namespace boost
  86
  87 #include <boost/atomic/detail/footer.hpp>
  88
  89 #endif // BOOST_ATOMIC_DETAIL_BITWISE_FP_CAST_HPP_INCLUDED_