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
25namespace llvm {
26namespace sys {
27
28/// SwapByteOrder_16 - This function returns a byte-swapped representation of
29/// the 16-bit argument.
30inline 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.
44inline 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.
60inline 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
72inline unsigned char getSwappedBytes(unsigned char C) { return C; }
73inline signed char getSwappedBytes(signed char C) { return C; }
74inline char getSwappedBytes(char C) { return C; }
75
76inline unsigned short getSwappedBytes(unsigned short C) { return SwapByteOrder_16(C); }
77inline signed short getSwappedBytes( signed short C) { return SwapByteOrder_16(C); }
78
79inline unsigned int getSwappedBytes(unsigned int C) { return SwapByteOrder_32(C); }
80inline signed int getSwappedBytes( signed int C) { return SwapByteOrder_32(C); }
81
82#if __LONG_MAX__ == __INT_MAX__
83inline unsigned long getSwappedBytes(unsigned long C) { return SwapByteOrder_32(C); }
84inline signed long getSwappedBytes( signed long C) { return SwapByteOrder_32(C); }
85#elif __LONG_MAX__ == __LONG_LONG_MAX__
86inline unsigned long getSwappedBytes(unsigned long C) { return SwapByteOrder_64(C); }
87inline signed long getSwappedBytes( signed long C) { return SwapByteOrder_64(C); }
88#else
89#error "Unknown long size!"
90#endif
91
92inline unsigned long long getSwappedBytes(unsigned long long C) {
93 return SwapByteOrder_64(C);
94}
95inline signed long long getSwappedBytes(signed long long C) {
96 return SwapByteOrder_64(C);
97}
98
99inline 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
109inline 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
119template<typename T>
120inline void swapByteOrder(T &Value) {
121 Value = getSwappedBytes(Value);
122}
123
124} // end namespace sys
125} // end namespace llvm
126
127#endif
128