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 <cstddef>
18#include <cstdint>
19#include <type_traits>
20#if defined(_MSC_VER) && !defined(_DEBUG)
21#include <stdlib.h>
22#endif
23
24#if defined(__linux__) || defined(__GNU__) || defined(__HAIKU__) || \
25 defined(__Fuchsia__) || defined(__EMSCRIPTEN__)
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#elif defined(__MVS__)
40#define BIG_ENDIAN 4321
41#define LITTLE_ENDIAN 1234
42#define BYTE_ORDER BIG_ENDIAN
43#else
44#if !defined(BYTE_ORDER) && !defined(_WIN32)
45#include <machine/endian.h>
46#endif
47#endif
48
49namespace llvm {
50
51/// ByteSwap_16 - This function returns a byte-swapped representation of
52/// the 16-bit argument.
53inline uint16_t ByteSwap_16(uint16_t value) {
54#if defined(_MSC_VER) && !defined(_DEBUG)
55 // The DLL version of the runtime lacks these functions (bug!?), but in a
56 // release build they're replaced with BSWAP instructions anyway.
57 return _byteswap_ushort(value);
58#else
59 uint16_t Hi = value << 8;
60 uint16_t Lo = value >> 8;
61 return Hi | Lo;
62#endif
63}
64
65/// This function returns a byte-swapped representation of the 32-bit argument.
66inline uint32_t ByteSwap_32(uint32_t value) {
67#if defined(__llvm__) || (defined(__GNUC__) && !defined(__ICC))
68 return __builtin_bswap32(value);
69#elif defined(_MSC_VER) && !defined(_DEBUG)
70 return _byteswap_ulong(value);
71#else
72 uint32_t Byte0 = value & 0x000000FF;
73 uint32_t Byte1 = value & 0x0000FF00;
74 uint32_t Byte2 = value & 0x00FF0000;
75 uint32_t Byte3 = value & 0xFF000000;
76 return (Byte0 << 24) | (Byte1 << 8) | (Byte2 >> 8) | (Byte3 >> 24);
77#endif
78}
79
80/// This function returns a byte-swapped representation of the 64-bit argument.
81inline uint64_t ByteSwap_64(uint64_t value) {
82#if defined(__llvm__) || (defined(__GNUC__) && !defined(__ICC))
83 return __builtin_bswap64(value);
84#elif defined(_MSC_VER) && !defined(_DEBUG)
85 return _byteswap_uint64(value);
86#else
87 uint64_t Hi = ByteSwap_32(uint32_t(value));
88 uint32_t Lo = ByteSwap_32(uint32_t(value >> 32));
89 return (Hi << 32) | Lo;
90#endif
91}
92
93namespace sys {
94
95#if defined(BYTE_ORDER) && defined(BIG_ENDIAN) && BYTE_ORDER == BIG_ENDIAN
96constexpr bool IsBigEndianHost = true;
97#else
98constexpr bool IsBigEndianHost = false;
99#endif
100
101static const bool IsLittleEndianHost = !IsBigEndianHost;
102
103inline unsigned char getSwappedBytes(unsigned char C) { return C; }
104inline signed char getSwappedBytes(signed char C) { return C; }
105inline char getSwappedBytes(char C) { return C; }
106
107inline unsigned short getSwappedBytes(unsigned short C) { return ByteSwap_16(C); }
108inline signed short getSwappedBytes( signed short C) { return ByteSwap_16(C); }
109
110inline unsigned int getSwappedBytes(unsigned int C) { return ByteSwap_32(C); }
111inline signed int getSwappedBytes( signed int C) { return ByteSwap_32(C); }
112
113inline unsigned long getSwappedBytes(unsigned long C) {
114 // Handle LLP64 and LP64 platforms.
115 return sizeof(long) == sizeof(int) ? ByteSwap_32((uint32_t)C)
116 : ByteSwap_64((uint64_t)C);
117}
118inline signed long getSwappedBytes(signed long C) {
119 // Handle LLP64 and LP64 platforms.
120 return sizeof(long) == sizeof(int) ? ByteSwap_32((uint32_t)C)
121 : ByteSwap_64((uint64_t)C);
122}
123
124inline unsigned long long getSwappedBytes(unsigned long long C) {
125 return ByteSwap_64(C);
126}
127inline signed long long getSwappedBytes(signed long long C) {
128 return ByteSwap_64(C);
129}
130
131inline float getSwappedBytes(float C) {
132 union {
133 uint32_t i;
134 float f;
135 } in, out;
136 in.f = C;
137 out.i = ByteSwap_32(in.i);
138 return out.f;
139}
140
141inline double getSwappedBytes(double C) {
142 union {
143 uint64_t i;
144 double d;
145 } in, out;
146 in.d = C;
147 out.i = ByteSwap_64(in.i);
148 return out.d;
149}
150
151template <typename T>
152inline std::enable_if_t<std::is_enum<T>::value, T> getSwappedBytes(T C) {
153 return static_cast<T>(
154 getSwappedBytes(static_cast<std::underlying_type_t<T>>(C)));
155}
156
157template<typename T>
158inline void swapByteOrder(T &Value) {
159 Value = getSwappedBytes(Value);
160}
161
162} // end namespace sys
163} // end namespace llvm
164
165#endif
166