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