LLVM  3.7.0
SwapByteOrder.h
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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 #include <limits>
22 
23 namespace llvm {
24 namespace sys {
25 
26 /// SwapByteOrder_16 - This function returns a byte-swapped representation of
27 /// the 16-bit argument.
28 inline uint16_t SwapByteOrder_16(uint16_t value) {
29 #if defined(_MSC_VER) && !defined(_DEBUG)
30  // The DLL version of the runtime lacks these functions (bug!?), but in a
31  // release build they're replaced with BSWAP instructions anyway.
32  return _byteswap_ushort(value);
33 #else
34  uint16_t Hi = value << 8;
35  uint16_t Lo = value >> 8;
36  return Hi | Lo;
37 #endif
38 }
39 
40 /// SwapByteOrder_32 - This function returns a byte-swapped representation of
41 /// the 32-bit argument.
42 inline uint32_t SwapByteOrder_32(uint32_t value) {
43 #if defined(__llvm__) || (LLVM_GNUC_PREREQ(4, 3, 0) && !defined(__ICC))
44  return __builtin_bswap32(value);
45 #elif defined(_MSC_VER) && !defined(_DEBUG)
46  return _byteswap_ulong(value);
47 #else
48  uint32_t Byte0 = value & 0x000000FF;
49  uint32_t Byte1 = value & 0x0000FF00;
50  uint32_t Byte2 = value & 0x00FF0000;
51  uint32_t Byte3 = value & 0xFF000000;
52  return (Byte0 << 24) | (Byte1 << 8) | (Byte2 >> 8) | (Byte3 >> 24);
53 #endif
54 }
55 
56 /// SwapByteOrder_64 - This function returns a byte-swapped representation of
57 /// the 64-bit argument.
58 inline uint64_t SwapByteOrder_64(uint64_t value) {
59 #if defined(__llvm__) || (LLVM_GNUC_PREREQ(4, 3, 0) && !defined(__ICC))
60  return __builtin_bswap64(value);
61 #elif defined(_MSC_VER) && !defined(_DEBUG)
62  return _byteswap_uint64(value);
63 #else
64  uint64_t Hi = SwapByteOrder_32(uint32_t(value));
65  uint32_t Lo = SwapByteOrder_32(uint32_t(value >> 32));
66  return (Hi << 32) | Lo;
67 #endif
68 }
69 
70 inline unsigned char getSwappedBytes(unsigned char C) { return C; }
71 inline signed char getSwappedBytes(signed char C) { return C; }
72 inline char getSwappedBytes(char C) { return C; }
73 
74 inline unsigned short getSwappedBytes(unsigned short C) { return SwapByteOrder_16(C); }
75 inline signed short getSwappedBytes( signed short C) { return SwapByteOrder_16(C); }
76 
77 inline unsigned int getSwappedBytes(unsigned int C) { return SwapByteOrder_32(C); }
78 inline signed int getSwappedBytes( signed int C) { return SwapByteOrder_32(C); }
79 
80 #if __LONG_MAX__ == __INT_MAX__
81 inline unsigned long getSwappedBytes(unsigned long C) { return SwapByteOrder_32(C); }
82 inline signed long getSwappedBytes( signed long C) { return SwapByteOrder_32(C); }
83 #elif __LONG_MAX__ == __LONG_LONG_MAX__
84 inline unsigned long getSwappedBytes(unsigned long C) { return SwapByteOrder_64(C); }
85 inline signed long getSwappedBytes( signed long C) { return SwapByteOrder_64(C); }
86 #else
87 #error "Unknown long size!"
88 #endif
89 
90 inline unsigned long long getSwappedBytes(unsigned long long C) {
91  return SwapByteOrder_64(C);
92 }
93 inline signed long long getSwappedBytes(signed long long C) {
94  return SwapByteOrder_64(C);
95 }
96 
97 inline float getSwappedBytes(float C) {
98  union {
99  uint32_t i;
100  float f;
101  } in, out;
102  in.f = C;
103  out.i = SwapByteOrder_32(in.i);
104  return out.f;
105 }
106 
107 inline double getSwappedBytes(double C) {
108  union {
109  uint64_t i;
110  double d;
111  } in, out;
112  in.d = C;
113  out.i = SwapByteOrder_64(in.i);
114  return out.d;
115 }
116 
117 template<typename T>
118 inline void swapByteOrder(T &Value) {
119  Value = getSwappedBytes(Value);
120 }
121 
122 } // end namespace sys
123 } // end namespace llvm
124 
125 #endif
void swapByteOrder(T &Value)
uint32_t SwapByteOrder_32(uint32_t value)
SwapByteOrder_32 - This function returns a byte-swapped representation of the 32-bit argument...
Definition: SwapByteOrder.h:42
uint16_t SwapByteOrder_16(uint16_t value)
SwapByteOrder_16 - This function returns a byte-swapped representation of the 16-bit argument...
Definition: SwapByteOrder.h:28
uint64_t SwapByteOrder_64(uint64_t value)
SwapByteOrder_64 - This function returns a byte-swapped representation of the 64-bit argument...
Definition: SwapByteOrder.h:58
unsigned char getSwappedBytes(unsigned char C)
Definition: SwapByteOrder.h:70
LLVM Value Representation.
Definition: Value.h:69