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.
SwapByteOrder_16(uint16_t value)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.
SwapByteOrder_32(uint32_t value)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.
SwapByteOrder_64(uint64_t value)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 
getSwappedBytes(unsigned char C)70 inline unsigned char  getSwappedBytes(unsigned char C) { return C; }
getSwappedBytes(signed char C)71 inline   signed char  getSwappedBytes(signed char C) { return C; }
getSwappedBytes(char C)72 inline          char  getSwappedBytes(char C) { return C; }
73 
getSwappedBytes(unsigned short C)74 inline unsigned short getSwappedBytes(unsigned short C) { return SwapByteOrder_16(C); }
getSwappedBytes(signed short C)75 inline   signed short getSwappedBytes(  signed short C) { return SwapByteOrder_16(C); }
76 
getSwappedBytes(unsigned int C)77 inline unsigned int   getSwappedBytes(unsigned int   C) { return SwapByteOrder_32(C); }
getSwappedBytes(signed int C)78 inline   signed int   getSwappedBytes(  signed int   C) { return SwapByteOrder_32(C); }
79 
80 #if __LONG_MAX__ == __INT_MAX__
getSwappedBytes(unsigned long C)81 inline unsigned long  getSwappedBytes(unsigned long  C) { return SwapByteOrder_32(C); }
getSwappedBytes(signed long C)82 inline   signed long  getSwappedBytes(  signed long  C) { return SwapByteOrder_32(C); }
83 #elif __LONG_MAX__ == __LONG_LONG_MAX__
getSwappedBytes(unsigned long C)84 inline unsigned long  getSwappedBytes(unsigned long  C) { return SwapByteOrder_64(C); }
getSwappedBytes(signed long C)85 inline   signed long  getSwappedBytes(  signed long  C) { return SwapByteOrder_64(C); }
86 #else
87 #error "Unknown long size!"
88 #endif
89 
getSwappedBytes(unsigned long long C)90 inline unsigned long long getSwappedBytes(unsigned long long C) {
91   return SwapByteOrder_64(C);
92 }
getSwappedBytes(signed long long C)93 inline signed long long getSwappedBytes(signed long long C) {
94   return SwapByteOrder_64(C);
95 }
96 
getSwappedBytes(float C)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 
getSwappedBytes(double C)107 inline float 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>
swapByteOrder(T & Value)118 inline void swapByteOrder(T &Value) {
119   Value = getSwappedBytes(Value);
120 }
121 
122 } // end namespace sys
123 } // end namespace llvm
124 
125 #endif
126