1 //===- SwapByteOrder.h - Generic and optimized byte swaps -------*- C++ -*-===//
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
7 //===----------------------------------------------------------------------===//
9 // This file declares generic and optimized functions to swap the byte order of
12 //===----------------------------------------------------------------------===//
14 #ifndef LLVM_SUPPORT_SWAPBYTEORDER_H
15 #define LLVM_SUPPORT_SWAPBYTEORDER_H
17 #include "llvm/Support/Compiler.h"
18 #include "llvm/Support/DataTypes.h"
20 #include <type_traits>
21 #if defined(_MSC_VER) && !defined(_DEBUG)
25 #if defined(__linux__) || defined(__GNU__) || defined(__HAIKU__)
28 #include <sys/machine.h>
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
37 #define BYTE_ORDER LITTLE_ENDIAN
40 #if !defined(BYTE_ORDER) && !defined(_WIN32)
41 #include <machine/endian.h>
48 #if defined(BYTE_ORDER) && defined(BIG_ENDIAN) && BYTE_ORDER == BIG_ENDIAN
49 constexpr bool IsBigEndianHost = true;
51 constexpr bool IsBigEndianHost = false;
54 static const bool IsLittleEndianHost = !IsBigEndianHost;
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);
64 uint16_t Hi = value << 8;
65 uint16_t Lo = value >> 8;
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);
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);
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);
92 uint64_t Hi = SwapByteOrder_32(uint32_t(value));
93 uint32_t Lo = SwapByteOrder_32(uint32_t(value >> 32));
94 return (Hi << 32) | Lo;
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; }
102 inline unsigned short getSwappedBytes(unsigned short C) { return SwapByteOrder_16(C); }
103 inline signed short getSwappedBytes( signed short C) { return SwapByteOrder_16(C); }
105 inline unsigned int getSwappedBytes(unsigned int C) { return SwapByteOrder_32(C); }
106 inline signed int getSwappedBytes( signed int C) { return SwapByteOrder_32(C); }
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); }
115 #error "Unknown long size!"
118 inline unsigned long long getSwappedBytes(unsigned long long C) {
119 return SwapByteOrder_64(C);
121 inline signed long long getSwappedBytes(signed long long C) {
122 return SwapByteOrder_64(C);
125 inline float getSwappedBytes(float C) {
131 out.i = SwapByteOrder_32(in.i);
135 inline double getSwappedBytes(double C) {
141 out.i = SwapByteOrder_64(in.i);
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)));
153 inline void swapByteOrder(T &Value) {
154 Value = getSwappedBytes(Value);
157 } // end namespace sys
158 } // end namespace llvm