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-exception 7 // 8 //===----------------------------------------------------------------------===// 9 10 #ifndef _LIBCPP___BIT_BYTESWAP_H 11 #define _LIBCPP___BIT_BYTESWAP_H 12 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_header 19 #endif 20 21 _LIBCPP_BEGIN_NAMESPACE_STD 22 23 #if _LIBCPP_STD_VER >= 23 24 25 template <integral _Tp> 26 _LIBCPP_NODISCARD_EXT _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 # ifndef _LIBCPP_HAS_NO_INT128 36 } else if constexpr (sizeof(_Tp) == 16) { 37 # if __has_builtin(__builtin_bswap128) 38 return __builtin_bswap128(__val); 39 # else 40 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_NO_INT128 44 } else { 45 static_assert(sizeof(_Tp) == 0, "byteswap is unimplemented for integral types of this size"); 46 } 47 } 48 49 #endif // _LIBCPP_STD_VER >= 23 50 51 _LIBCPP_END_NAMESPACE_STD 52 53 #endif // _LIBCPP___BIT_BYTESWAP_H 54