1 //===- SwapByteOrder.h - Generic and optimized byte swaps -------*- C++ -*-===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 // 9 // This file declares generic and optimized functions to swap the byte order of 10 // an integral type. 11 // 12 //===----------------------------------------------------------------------===// 13 14 #ifndef LLVM_SUPPORT_SWAPBYTEORDER_H 15 #define LLVM_SUPPORT_SWAPBYTEORDER_H 16 17 #include "llvm/Support/Compiler.h" 18 #include "llvm/Support/DataTypes.h" 19 #include <cstddef> 20 #include <type_traits> 21 #if defined(_MSC_VER) && !defined(_DEBUG) 22 #include <stdlib.h> 23 #endif 24 25 #if defined(__linux__) || defined(__GNU__) || defined(__HAIKU__) 26 #include <endian.h> 27 #elif defined(_AIX) 28 #include <sys/machine.h> 29 #elif defined(__sun) 30 /* Solaris provides _BIG_ENDIAN/_LITTLE_ENDIAN selector in sys/types.h */ 31 #include <sys/types.h> 32 #define BIG_ENDIAN 4321 33 #define LITTLE_ENDIAN 1234 34 #if defined(_BIG_ENDIAN) 35 #define BYTE_ORDER BIG_ENDIAN 36 #else 37 #define BYTE_ORDER LITTLE_ENDIAN 38 #endif 39 #else 40 #if !defined(BYTE_ORDER) && !defined(_WIN32) 41 #include <machine/endian.h> 42 #endif 43 #endif 44 45 namespace llvm { 46 namespace sys { 47 48 #if defined(BYTE_ORDER) && defined(BIG_ENDIAN) && BYTE_ORDER == BIG_ENDIAN 49 constexpr bool IsBigEndianHost = true; 50 #else 51 constexpr bool IsBigEndianHost = false; 52 #endif 53 54 static const bool IsLittleEndianHost = !IsBigEndianHost; 55 56 /// SwapByteOrder_16 - This function returns a byte-swapped representation of 57 /// the 16-bit argument. 58 inline uint16_t SwapByteOrder_16(uint16_t value) { 59 #if defined(_MSC_VER) && !defined(_DEBUG) 60 // The DLL version of the runtime lacks these functions (bug!?), but in a 61 // release build they're replaced with BSWAP instructions anyway. 62 return _byteswap_ushort(value); 63 #else 64 uint16_t Hi = value << 8; 65 uint16_t Lo = value >> 8; 66 return Hi | Lo; 67 #endif 68 } 69 70 /// This function returns a byte-swapped representation of the 32-bit argument. 71 inline uint32_t SwapByteOrder_32(uint32_t value) { 72 #if defined(__llvm__) || (defined(__GNUC__) && !defined(__ICC)) 73 return __builtin_bswap32(value); 74 #elif defined(_MSC_VER) && !defined(_DEBUG) 75 return _byteswap_ulong(value); 76 #else 77 uint32_t Byte0 = value & 0x000000FF; 78 uint32_t Byte1 = value & 0x0000FF00; 79 uint32_t Byte2 = value & 0x00FF0000; 80 uint32_t Byte3 = value & 0xFF000000; 81 return (Byte0 << 24) | (Byte1 << 8) | (Byte2 >> 8) | (Byte3 >> 24); 82 #endif 83 } 84 85 /// This function returns a byte-swapped representation of the 64-bit argument. 86 inline uint64_t SwapByteOrder_64(uint64_t value) { 87 #if defined(__llvm__) || (defined(__GNUC__) && !defined(__ICC)) 88 return __builtin_bswap64(value); 89 #elif defined(_MSC_VER) && !defined(_DEBUG) 90 return _byteswap_uint64(value); 91 #else 92 uint64_t Hi = SwapByteOrder_32(uint32_t(value)); 93 uint32_t Lo = SwapByteOrder_32(uint32_t(value >> 32)); 94 return (Hi << 32) | Lo; 95 #endif 96 } 97 98 inline unsigned char getSwappedBytes(unsigned char C) { return C; } 99 inline signed char getSwappedBytes(signed char C) { return C; } 100 inline char getSwappedBytes(char C) { return C; } 101 102 inline unsigned short getSwappedBytes(unsigned short C) { return SwapByteOrder_16(C); } 103 inline signed short getSwappedBytes( signed short C) { return SwapByteOrder_16(C); } 104 105 inline unsigned int getSwappedBytes(unsigned int C) { return SwapByteOrder_32(C); } 106 inline signed int getSwappedBytes( signed int C) { return SwapByteOrder_32(C); } 107 108 #if __LONG_MAX__ == __INT_MAX__ 109 inline unsigned long getSwappedBytes(unsigned long C) { return SwapByteOrder_32(C); } 110 inline signed long getSwappedBytes( signed long C) { return SwapByteOrder_32(C); } 111 #elif __LONG_MAX__ == __LONG_LONG_MAX__ 112 inline unsigned long getSwappedBytes(unsigned long C) { return SwapByteOrder_64(C); } 113 inline signed long getSwappedBytes( signed long C) { return SwapByteOrder_64(C); } 114 #else 115 #error "Unknown long size!" 116 #endif 117 118 inline unsigned long long getSwappedBytes(unsigned long long C) { 119 return SwapByteOrder_64(C); 120 } 121 inline signed long long getSwappedBytes(signed long long C) { 122 return SwapByteOrder_64(C); 123 } 124 125 inline float getSwappedBytes(float C) { 126 union { 127 uint32_t i; 128 float f; 129 } in, out; 130 in.f = C; 131 out.i = SwapByteOrder_32(in.i); 132 return out.f; 133 } 134 135 inline double getSwappedBytes(double C) { 136 union { 137 uint64_t i; 138 double d; 139 } in, out; 140 in.d = C; 141 out.i = SwapByteOrder_64(in.i); 142 return out.d; 143 } 144 145 template <typename T> 146 inline typename std::enable_if<std::is_enum<T>::value, T>::type 147 getSwappedBytes(T C) { 148 return static_cast<T>( 149 getSwappedBytes(static_cast<typename std::underlying_type<T>::type>(C))); 150 } 151 152 template<typename T> 153 inline void swapByteOrder(T &Value) { 154 Value = getSwappedBytes(Value); 155 } 156 157 } // end namespace sys 158 } // end namespace llvm 159 160 #endif 161