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 #if defined(_MSC_VER) && !defined(_DEBUG)
22 #include <stdlib.h>
23 #endif
24 
25 namespace llvm {
26 namespace sys {
27 
28 /// SwapByteOrder_16 - This function returns a byte-swapped representation of
29 /// the 16-bit argument.
SwapByteOrder_16(uint16_t value)30 inline uint16_t SwapByteOrder_16(uint16_t value) {
31 #if defined(_MSC_VER) && !defined(_DEBUG)
32   // The DLL version of the runtime lacks these functions (bug!?), but in a
33   // release build they're replaced with BSWAP instructions anyway.
34   return _byteswap_ushort(value);
35 #else
36   uint16_t Hi = value << 8;
37   uint16_t Lo = value >> 8;
38   return Hi | Lo;
39 #endif
40 }
41 
42 /// SwapByteOrder_32 - This function returns a byte-swapped representation of
43 /// the 32-bit argument.
SwapByteOrder_32(uint32_t value)44 inline uint32_t SwapByteOrder_32(uint32_t value) {
45 #if defined(__llvm__) || (LLVM_GNUC_PREREQ(4, 3, 0) && !defined(__ICC))
46   return __builtin_bswap32(value);
47 #elif defined(_MSC_VER) && !defined(_DEBUG)
48   return _byteswap_ulong(value);
49 #else
50   uint32_t Byte0 = value & 0x000000FF;
51   uint32_t Byte1 = value & 0x0000FF00;
52   uint32_t Byte2 = value & 0x00FF0000;
53   uint32_t Byte3 = value & 0xFF000000;
54   return (Byte0 << 24) | (Byte1 << 8) | (Byte2 >> 8) | (Byte3 >> 24);
55 #endif
56 }
57 
58 /// SwapByteOrder_64 - This function returns a byte-swapped representation of
59 /// the 64-bit argument.
SwapByteOrder_64(uint64_t value)60 inline uint64_t SwapByteOrder_64(uint64_t value) {
61 #if defined(__llvm__) || (LLVM_GNUC_PREREQ(4, 3, 0) && !defined(__ICC))
62   return __builtin_bswap64(value);
63 #elif defined(_MSC_VER) && !defined(_DEBUG)
64   return _byteswap_uint64(value);
65 #else
66   uint64_t Hi = SwapByteOrder_32(uint32_t(value));
67   uint32_t Lo = SwapByteOrder_32(uint32_t(value >> 32));
68   return (Hi << 32) | Lo;
69 #endif
70 }
71 
getSwappedBytes(unsigned char C)72 inline unsigned char  getSwappedBytes(unsigned char C) { return C; }
getSwappedBytes(signed char C)73 inline   signed char  getSwappedBytes(signed char C) { return C; }
getSwappedBytes(char C)74 inline          char  getSwappedBytes(char C) { return C; }
75 
getSwappedBytes(unsigned short C)76 inline unsigned short getSwappedBytes(unsigned short C) { return SwapByteOrder_16(C); }
getSwappedBytes(signed short C)77 inline   signed short getSwappedBytes(  signed short C) { return SwapByteOrder_16(C); }
78 
getSwappedBytes(unsigned int C)79 inline unsigned int   getSwappedBytes(unsigned int   C) { return SwapByteOrder_32(C); }
getSwappedBytes(signed int C)80 inline   signed int   getSwappedBytes(  signed int   C) { return SwapByteOrder_32(C); }
81 
82 #if __LONG_MAX__ == __INT_MAX__
getSwappedBytes(unsigned long C)83 inline unsigned long  getSwappedBytes(unsigned long  C) { return SwapByteOrder_32(C); }
getSwappedBytes(signed long C)84 inline   signed long  getSwappedBytes(  signed long  C) { return SwapByteOrder_32(C); }
85 #elif __LONG_MAX__ == __LONG_LONG_MAX__
getSwappedBytes(unsigned long C)86 inline unsigned long  getSwappedBytes(unsigned long  C) { return SwapByteOrder_64(C); }
getSwappedBytes(signed long C)87 inline   signed long  getSwappedBytes(  signed long  C) { return SwapByteOrder_64(C); }
88 #else
89 #error "Unknown long size!"
90 #endif
91 
getSwappedBytes(unsigned long long C)92 inline unsigned long long getSwappedBytes(unsigned long long C) {
93   return SwapByteOrder_64(C);
94 }
getSwappedBytes(signed long long C)95 inline signed long long getSwappedBytes(signed long long C) {
96   return SwapByteOrder_64(C);
97 }
98 
getSwappedBytes(float C)99 inline float getSwappedBytes(float C) {
100   union {
101     uint32_t i;
102     float f;
103   } in, out;
104   in.f = C;
105   out.i = SwapByteOrder_32(in.i);
106   return out.f;
107 }
108 
getSwappedBytes(double C)109 inline double getSwappedBytes(double C) {
110   union {
111     uint64_t i;
112     double d;
113   } in, out;
114   in.d = C;
115   out.i = SwapByteOrder_64(in.i);
116   return out.d;
117 }
118 
119 template<typename T>
swapByteOrder(T & Value)120 inline void swapByteOrder(T &Value) {
121   Value = getSwappedBytes(Value);
122 }
123 
124 } // end namespace sys
125 } // end namespace llvm
126 
127 #endif
128