1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4
5 // This header defines cross-platform ByteSwap() implementations for 16, 32 and
6 // 64-bit values, and NetToHostXX() / HostToNextXX() functions equivalent to
7 // the traditional ntohX() and htonX() functions.
8 // Use the functions defined here rather than using the platform-specific
9 // functions directly.
10
11 #ifndef BASE_SYS_BYTEORDER_H_
12 #define BASE_SYS_BYTEORDER_H_
13
14 #include <stdint.h>
15
16 #include "base/logging.h"
17 #include "build/build_config.h"
18
19 #if defined(COMPILER_MSVC)
20 #include <stdlib.h>
21 #endif
22
23 namespace base {
24
25 // Returns a value with all bytes in |x| swapped, i.e. reverses the endianness.
ByteSwap(uint16_t x)26 inline uint16_t ByteSwap(uint16_t x) {
27 #if defined(COMPILER_MSVC)
28 return _byteswap_ushort(x);
29 #else
30 return __builtin_bswap16(x);
31 #endif
32 }
33
ByteSwap(uint32_t x)34 inline uint32_t ByteSwap(uint32_t x) {
35 #if defined(COMPILER_MSVC)
36 return _byteswap_ulong(x);
37 #else
38 return __builtin_bswap32(x);
39 #endif
40 }
41
ByteSwap(uint64_t x)42 inline uint64_t ByteSwap(uint64_t x) {
43 #if defined(COMPILER_MSVC)
44 return _byteswap_uint64(x);
45 #else
46 return __builtin_bswap64(x);
47 #endif
48 }
49
ByteSwapUintPtrT(uintptr_t x)50 inline uintptr_t ByteSwapUintPtrT(uintptr_t x) {
51 // We do it this way because some build configurations are ILP32 even when
52 // defined(ARCH_CPU_64_BITS). Unfortunately, we can't use sizeof in #ifs. But,
53 // because these conditionals are constexprs, the irrelevant branches will
54 // likely be optimized away, so this construction should not result in code
55 // bloat.
56 if (sizeof(uintptr_t) == 4) {
57 return ByteSwap(static_cast<uint32_t>(x));
58 } else if (sizeof(uintptr_t) == 8) {
59 return ByteSwap(static_cast<uint64_t>(x));
60 } else {
61 NOTREACHED();
62 }
63 }
64
65 // Converts the bytes in |x| from host order (endianness) to little endian, and
66 // returns the result.
ByteSwapToLE16(uint16_t x)67 inline uint16_t ByteSwapToLE16(uint16_t x) {
68 #if defined(ARCH_CPU_LITTLE_ENDIAN)
69 return x;
70 #else
71 return ByteSwap(x);
72 #endif
73 }
ByteSwapToLE32(uint32_t x)74 inline uint32_t ByteSwapToLE32(uint32_t x) {
75 #if defined(ARCH_CPU_LITTLE_ENDIAN)
76 return x;
77 #else
78 return ByteSwap(x);
79 #endif
80 }
ByteSwapToLE64(uint64_t x)81 inline uint64_t ByteSwapToLE64(uint64_t x) {
82 #if defined(ARCH_CPU_LITTLE_ENDIAN)
83 return x;
84 #else
85 return ByteSwap(x);
86 #endif
87 }
88
89 // Converts the bytes in |x| from network to host order (endianness), and
90 // returns the result.
NetToHost16(uint16_t x)91 inline uint16_t NetToHost16(uint16_t x) {
92 #if defined(ARCH_CPU_LITTLE_ENDIAN)
93 return ByteSwap(x);
94 #else
95 return x;
96 #endif
97 }
NetToHost32(uint32_t x)98 inline uint32_t NetToHost32(uint32_t x) {
99 #if defined(ARCH_CPU_LITTLE_ENDIAN)
100 return ByteSwap(x);
101 #else
102 return x;
103 #endif
104 }
NetToHost64(uint64_t x)105 inline uint64_t NetToHost64(uint64_t x) {
106 #if defined(ARCH_CPU_LITTLE_ENDIAN)
107 return ByteSwap(x);
108 #else
109 return x;
110 #endif
111 }
112
113 // Converts the bytes in |x| from host to network order (endianness), and
114 // returns the result.
HostToNet16(uint16_t x)115 inline uint16_t HostToNet16(uint16_t x) {
116 #if defined(ARCH_CPU_LITTLE_ENDIAN)
117 return ByteSwap(x);
118 #else
119 return x;
120 #endif
121 }
HostToNet32(uint32_t x)122 inline uint32_t HostToNet32(uint32_t x) {
123 #if defined(ARCH_CPU_LITTLE_ENDIAN)
124 return ByteSwap(x);
125 #else
126 return x;
127 #endif
128 }
HostToNet64(uint64_t x)129 inline uint64_t HostToNet64(uint64_t x) {
130 #if defined(ARCH_CPU_LITTLE_ENDIAN)
131 return ByteSwap(x);
132 #else
133 return x;
134 #endif
135 }
136
137 } // namespace base
138
139 #endif // BASE_SYS_BYTEORDER_H_
140