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- #ifndef BOOST_ENDIAN_DETAIL_ENDIAN_REVERSE_HPP_INCLUDED
- #define BOOST_ENDIAN_DETAIL_ENDIAN_REVERSE_HPP_INCLUDED
- // Copyright 2019 Peter Dimov
- //
- // Distributed under the Boost Software License, Version 1.0.
- // http://www.boost.org/LICENSE_1_0.txt
- #include <boost/endian/detail/integral_by_size.hpp>
- #include <boost/endian/detail/intrinsic.hpp>
- #include <boost/type_traits/is_integral.hpp>
- #include <boost/type_traits/is_same.hpp>
- #include <boost/static_assert.hpp>
- #include <boost/cstdint.hpp>
- #include <boost/config.hpp>
- #include <cstddef>
- #include <cstring>
- #if defined(BOOST_ENDIAN_NO_INTRINSICS)
- # if defined(BOOST_NO_CXX14_CONSTEXPR)
- # define BOOST_ENDIAN_CONSTEXPR
- # else
- # define BOOST_ENDIAN_CONSTEXPR constexpr
- # endif
- #else
- # if defined(BOOST_ENDIAN_CONSTEXPR_INTRINSICS)
- # define BOOST_ENDIAN_CONSTEXPR BOOST_CONSTEXPR
- # else
- # define BOOST_ENDIAN_CONSTEXPR
- # endif
- #endif
- namespace boost
- {
- namespace endian
- {
- namespace detail
- {
- // -- portable approach suggested by tymofey, with avoidance of undefined behavior
- // as suggested by Giovanni Piero Deretta, with a further refinement suggested
- // by Pyry Jahkola.
- // -- intrinsic approach suggested by reviewers, and by David Stone, who provided
- // his Boost licensed macro implementation (detail/intrinsic.hpp)
- inline uint8_t BOOST_CONSTEXPR endian_reverse_impl( uint8_t x ) BOOST_NOEXCEPT
- {
- return x;
- }
- inline uint16_t BOOST_ENDIAN_CONSTEXPR endian_reverse_impl( uint16_t x ) BOOST_NOEXCEPT
- {
- #ifdef BOOST_ENDIAN_NO_INTRINSICS
- return (x << 8) | (x >> 8);
- #else
- return BOOST_ENDIAN_INTRINSIC_BYTE_SWAP_2(x);
- #endif
- }
- inline uint32_t BOOST_ENDIAN_CONSTEXPR endian_reverse_impl( uint32_t x ) BOOST_NOEXCEPT
- {
- #ifdef BOOST_ENDIAN_NO_INTRINSICS
- uint32_t step16 = x << 16 | x >> 16;
- return ((step16 << 8) & 0xff00ff00) | ((step16 >> 8) & 0x00ff00ff);
- #else
- return BOOST_ENDIAN_INTRINSIC_BYTE_SWAP_4(x);
- #endif
- }
- inline uint64_t BOOST_ENDIAN_CONSTEXPR endian_reverse_impl( uint64_t x ) BOOST_NOEXCEPT
- {
- #ifdef BOOST_ENDIAN_NO_INTRINSICS
- uint64_t step32 = x << 32 | x >> 32;
- uint64_t step16 = (step32 & 0x0000FFFF0000FFFFULL) << 16 | (step32 & 0xFFFF0000FFFF0000ULL) >> 16;
- return (step16 & 0x00FF00FF00FF00FFULL) << 8 | (step16 & 0xFF00FF00FF00FF00ULL) >> 8;
- #else
- return BOOST_ENDIAN_INTRINSIC_BYTE_SWAP_8(x);
- # endif
- }
- #if defined(BOOST_HAS_INT128)
- inline uint128_type BOOST_ENDIAN_CONSTEXPR endian_reverse_impl( uint128_type x ) BOOST_NOEXCEPT
- {
- return endian_reverse_impl( static_cast<uint64_t>( x >> 64 ) ) |
- static_cast<uint128_type>( endian_reverse_impl( static_cast<uint64_t>( x ) ) ) << 64;
- }
- #endif
- } // namespace detail
- // Requires:
- // T is non-bool integral
- template<class T> inline BOOST_CONSTEXPR T endian_reverse( T x ) BOOST_NOEXCEPT
- {
- BOOST_STATIC_ASSERT( is_integral<T>::value && !(is_same<T, bool>::value) );
- typedef typename detail::integral_by_size< sizeof(T) >::type uintN_t;
- return static_cast<T>( detail::endian_reverse_impl( static_cast<uintN_t>( x ) ) );
- }
- template <class EndianReversible>
- inline void endian_reverse_inplace(EndianReversible& x) BOOST_NOEXCEPT
- {
- x = endian_reverse( x );
- }
- } // namespace endian
- } // namespace boost
- #endif // BOOST_ENDIAN_DETAIL_ENDIAN_REVERSE_HPP_INCLUDED
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