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 #include <cstdlib> 17 18 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 19 # pragma GCC system_header 20 #endif 21 22 _LIBCPP_BEGIN_NAMESPACE_STD 23 24 #if _LIBCPP_STD_VER > 20 25 26 template <integral _Tp> 27 _LIBCPP_HIDE_FROM_ABI constexpr _Tp byteswap(_Tp __val) noexcept { 28 29 if constexpr (sizeof(_Tp) == 1) { 30 return __val; 31 } else if constexpr (sizeof(_Tp) == 2) { 32 return __builtin_bswap16(__val); 33 } else if constexpr (sizeof(_Tp) == 4) { 34 return __builtin_bswap32(__val); 35 } else if constexpr (sizeof(_Tp) == 8) { 36 return __builtin_bswap64(__val); 37 #ifndef _LIBCPP_HAS_NO_INT128 38 } else if constexpr (sizeof(_Tp) == 16) { 39 #if __has_builtin(__builtin_bswap128) 40 return __builtin_bswap128(__val); 41 #else 42 return static_cast<_Tp>(byteswap(static_cast<uint64_t>(__val))) << 64 | 43 static_cast<_Tp>(byteswap(static_cast<uint64_t>(__val >> 64))); 44 #endif // __has_builtin(__builtin_bswap128) 45 #endif // _LIBCPP_HAS_NO_INT128 46 } else { 47 static_assert(sizeof(_Tp) == 0, "byteswap is unimplemented for integral types of this size"); 48 } 49 } 50 51 #endif // _LIBCPP_STD_VER > 20 52 53 _LIBCPP_END_NAMESPACE_STD 54 55 #endif // _LIBCPP___BIT_BYTESWAP_H 56