54 lines · c
1// -*- C++ -*-2//===----------------------------------------------------------------------===//3//4// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.5// See https://llvm.org/LICENSE.txt for license information.6// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception7//8//===----------------------------------------------------------------------===//9 10#ifndef _LIBCPP___BIT_BYTESWAP_H11#define _LIBCPP___BIT_BYTESWAP_H12 13#include <__concepts/arithmetic.h>14#include <__config>15#include <cstdint>16 17#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)18# pragma GCC system_header19#endif20 21_LIBCPP_BEGIN_NAMESPACE_STD22 23#if _LIBCPP_STD_VER >= 2324 25template <integral _Tp>26[[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr _Tp byteswap(_Tp __val) noexcept {27 if constexpr (sizeof(_Tp) == 1) {28 return __val;29 } else if constexpr (sizeof(_Tp) == 2) {30 return __builtin_bswap16(__val);31 } else if constexpr (sizeof(_Tp) == 4) {32 return __builtin_bswap32(__val);33 } else if constexpr (sizeof(_Tp) == 8) {34 return __builtin_bswap64(__val);35# if _LIBCPP_HAS_INT12836 } else if constexpr (sizeof(_Tp) == 16) {37# if __has_builtin(__builtin_bswap128)38 return __builtin_bswap128(__val);39# else40 return static_cast<_Tp>(byteswap(static_cast<uint64_t>(__val))) << 64 |41 static_cast<_Tp>(byteswap(static_cast<uint64_t>(__val >> 64)));42# endif // __has_builtin(__builtin_bswap128)43# endif // _LIBCPP_HAS_INT12844 } else {45 static_assert(sizeof(_Tp) == 0, "byteswap is unimplemented for integral types of this size");46 }47}48 49#endif // _LIBCPP_STD_VER >= 2350 51_LIBCPP_END_NAMESPACE_STD52 53#endif // _LIBCPP___BIT_BYTESWAP_H54