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 45namespace llvm { 46namespace sys { 47 48#if defined(BYTE_ORDER) && defined(BIG_ENDIAN) && BYTE_ORDER == BIG_ENDIAN 49constexpr bool IsBigEndianHost = true; 50#else 51constexpr bool IsBigEndianHost = false; 52#endif 53 54static const bool IsLittleEndianHost = !IsBigEndianHost; 55 56/// SwapByteOrder_16 - This function returns a byte-swapped representation of 57/// the 16-bit argument. 58inline 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. 71inline 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. 86inline 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 98inline unsigned char getSwappedBytes(unsigned char C) { return C; } 99inline signed char getSwappedBytes(signed char C) { return C; } 100inline char getSwappedBytes(char C) { return C; } 101 102inline unsigned short getSwappedBytes(unsigned short C) { return SwapByteOrder_16(C); } 103inline signed short getSwappedBytes( signed short C) { return SwapByteOrder_16(C); } 104 105inline unsigned int getSwappedBytes(unsigned int C) { return SwapByteOrder_32(C); } 106inline signed int getSwappedBytes( signed int C) { return SwapByteOrder_32(C); } 107 108#if __LONG_MAX__ == __INT_MAX__ 109inline unsigned long getSwappedBytes(unsigned long C) { return SwapByteOrder_32(C); } 110inline signed long getSwappedBytes( signed long C) { return SwapByteOrder_32(C); } 111#elif __LONG_MAX__ == __LONG_LONG_MAX__ 112inline unsigned long getSwappedBytes(unsigned long C) { return SwapByteOrder_64(C); } 113inline signed long getSwappedBytes( signed long C) { return SwapByteOrder_64(C); } 114#else 115#error "Unknown long size!" 116#endif 117 118inline unsigned long long getSwappedBytes(unsigned long long C) { 119 return SwapByteOrder_64(C); 120} 121inline signed long long getSwappedBytes(signed long long C) { 122 return SwapByteOrder_64(C); 123} 124 125inline 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 135inline 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 145template <typename T> 146inline typename std::enable_if<std::is_enum<T>::value, T>::type 147getSwappedBytes(T C) { 148 return static_cast<T>( 149 getSwappedBytes(static_cast<typename std::underlying_type<T>::type>(C))); 150} 151 152template<typename T> 153inline void swapByteOrder(T &Value) { 154 Value = getSwappedBytes(Value); 155} 156 157} // end namespace sys 158} // end namespace llvm 159 160#endif 161