LLVM  10.0.0svn
SwapByteOrder.h
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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.
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
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
uint64_t CallInst * C
void swapByteOrder(T &Value)
This class represents lattice values for constants.
Definition: AllocatorList.h:23
constexpr bool IsBigEndianHost
Definition: SwapByteOrder.h:51
uint32_t SwapByteOrder_32(uint32_t value)
This function returns a byte-swapped representation of the 32-bit argument.
Definition: SwapByteOrder.h:71
static const bool IsLittleEndianHost
Definition: SwapByteOrder.h:54
uint16_t SwapByteOrder_16(uint16_t value)
SwapByteOrder_16 - This function returns a byte-swapped representation of the 16-bit argument...
Definition: SwapByteOrder.h:58
uint64_t SwapByteOrder_64(uint64_t value)
This function returns a byte-swapped representation of the 64-bit argument.
Definition: SwapByteOrder.h:86
unsigned char getSwappedBytes(unsigned char C)
Definition: SwapByteOrder.h:98
LLVM Value Representation.
Definition: Value.h:74