1//===- SwapByteOrder.h - Generic and optimized byte swaps -------*- C++ -*-===// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file is distributed under the University of Illinois Open Source 6// License. See LICENSE.TXT for details. 7// 8//===----------------------------------------------------------------------===// 9// 10// This file declares generic and optimized functions to swap the byte order of 11// an integral type. 12// 13//===----------------------------------------------------------------------===// 14 15#ifndef LLVM_SUPPORT_SWAPBYTEORDER_H 16#define LLVM_SUPPORT_SWAPBYTEORDER_H 17 18#include "llvm/Support/Compiler.h" 19#include "llvm/Support/DataTypes.h" 20#include <cstddef> 21 22namespace llvm { 23namespace sys { 24 25/// SwapByteOrder_16 - This function returns a byte-swapped representation of 26/// the 16-bit argument. 27inline uint16_t SwapByteOrder_16(uint16_t value) { 28#if defined(_MSC_VER) && !defined(_DEBUG) 29 // The DLL version of the runtime lacks these functions (bug!?), but in a 30 // release build they're replaced with BSWAP instructions anyway. 31 return _byteswap_ushort(value); 32#else 33 uint16_t Hi = value << 8; 34 uint16_t Lo = value >> 8; 35 return Hi | Lo; 36#endif 37} 38 39/// SwapByteOrder_32 - This function returns a byte-swapped representation of 40/// the 32-bit argument. 41inline uint32_t SwapByteOrder_32(uint32_t value) { 42#if defined(__llvm__) || (LLVM_GNUC_PREREQ(4, 3, 0) && !defined(__ICC)) 43 return __builtin_bswap32(value); 44#elif defined(_MSC_VER) && !defined(_DEBUG) 45 return _byteswap_ulong(value); 46#else 47 uint32_t Byte0 = value & 0x000000FF; 48 uint32_t Byte1 = value & 0x0000FF00; 49 uint32_t Byte2 = value & 0x00FF0000; 50 uint32_t Byte3 = value & 0xFF000000; 51 return (Byte0 << 24) | (Byte1 << 8) | (Byte2 >> 8) | (Byte3 >> 24); 52#endif 53} 54 55/// SwapByteOrder_64 - This function returns a byte-swapped representation of 56/// the 64-bit argument. 57inline uint64_t SwapByteOrder_64(uint64_t value) { 58#if defined(__llvm__) || (LLVM_GNUC_PREREQ(4, 3, 0) && !defined(__ICC)) 59 return __builtin_bswap64(value); 60#elif defined(_MSC_VER) && !defined(_DEBUG) 61 return _byteswap_uint64(value); 62#else 63 uint64_t Hi = SwapByteOrder_32(uint32_t(value)); 64 uint32_t Lo = SwapByteOrder_32(uint32_t(value >> 32)); 65 return (Hi << 32) | Lo; 66#endif 67} 68 69inline unsigned char getSwappedBytes(unsigned char C) { return C; } 70inline signed char getSwappedBytes(signed char C) { return C; } 71inline char getSwappedBytes(char C) { return C; } 72 73inline unsigned short getSwappedBytes(unsigned short C) { return SwapByteOrder_16(C); } 74inline signed short getSwappedBytes( signed short C) { return SwapByteOrder_16(C); } 75 76inline unsigned int getSwappedBytes(unsigned int C) { return SwapByteOrder_32(C); } 77inline signed int getSwappedBytes( signed int C) { return SwapByteOrder_32(C); } 78 79#if __LONG_MAX__ == __INT_MAX__ 80inline unsigned long getSwappedBytes(unsigned long C) { return SwapByteOrder_32(C); } 81inline signed long getSwappedBytes( signed long C) { return SwapByteOrder_32(C); } 82#elif __LONG_MAX__ == __LONG_LONG_MAX__ 83inline unsigned long getSwappedBytes(unsigned long C) { return SwapByteOrder_64(C); } 84inline signed long getSwappedBytes( signed long C) { return SwapByteOrder_64(C); } 85#else 86#error "Unknown long size!" 87#endif 88 89inline unsigned long long getSwappedBytes(unsigned long long C) { 90 return SwapByteOrder_64(C); 91} 92inline signed long long getSwappedBytes(signed long long C) { 93 return SwapByteOrder_64(C); 94} 95 96inline float getSwappedBytes(float C) { 97 union { 98 uint32_t i; 99 float f; 100 } in, out; 101 in.f = C; 102 out.i = SwapByteOrder_32(in.i); 103 return out.f; 104} 105 106inline double getSwappedBytes(double C) { 107 union { 108 uint64_t i; 109 double d; 110 } in, out; 111 in.d = C; 112 out.i = SwapByteOrder_64(in.i); 113 return out.d; 114} 115 116template<typename T> 117inline void swapByteOrder(T &Value) { 118 Value = getSwappedBytes(Value); 119} 120 121} // end namespace sys 122} // end namespace llvm 123 124#endif 125