[email protected] | d9806a9 | 2014-02-26 18:14:57 | [diff] [blame] | 1 | // Copyright 2014 The Chromium Authors. All rights reserved. |
[email protected] | 7556ea2 | 2011-12-08 19:29:15 | [diff] [blame] | 2 | // Use of this source code is governed by a BSD-style license that can be |
3 | // found in the LICENSE file. | ||||
4 | |||||
[email protected] | d9806a9 | 2014-02-26 18:14:57 | [diff] [blame] | 5 | #ifndef BASE_BIG_ENDIAN_H_ |
6 | #define BASE_BIG_ENDIAN_H_ | ||||
[email protected] | 7556ea2 | 2011-12-08 19:29:15 | [diff] [blame] | 7 | |
[email protected] | d9806a9 | 2014-02-26 18:14:57 | [diff] [blame] | 8 | #include "base/base_export.h" |
[email protected] | 7556ea2 | 2011-12-08 19:29:15 | [diff] [blame] | 9 | #include "base/basictypes.h" |
[email protected] | d069c11 | 2013-04-13 00:01:55 | [diff] [blame] | 10 | #include "base/strings/string_piece.h" |
[email protected] | 7556ea2 | 2011-12-08 19:29:15 | [diff] [blame] | 11 | |
[email protected] | d9806a9 | 2014-02-26 18:14:57 | [diff] [blame] | 12 | namespace base { |
[email protected] | 7556ea2 | 2011-12-08 19:29:15 | [diff] [blame] | 13 | |
14 | // Read an integer (signed or unsigned) from |buf| in Big Endian order. | ||||
15 | // Note: this loop is unrolled with -O1 and above. | ||||
16 | // NOTE(szym): glibc dns-canon.c and SpdyFrameBuilder use | ||||
17 | // ntohs(*(uint16_t*)ptr) which is potentially unaligned. | ||||
18 | // This would cause SIGBUS on ARMv5 or earlier and ARMv6-M. | ||||
19 | template<typename T> | ||||
20 | inline void ReadBigEndian(const char buf[], T* out) { | ||||
21 | *out = buf[0]; | ||||
22 | for (size_t i = 1; i < sizeof(T); ++i) { | ||||
23 | *out <<= 8; | ||||
24 | // Must cast to uint8 to avoid clobbering by sign extension. | ||||
25 | *out |= static_cast<uint8>(buf[i]); | ||||
26 | } | ||||
27 | } | ||||
28 | |||||
29 | // Write an integer (signed or unsigned) |val| to |buf| in Big Endian order. | ||||
30 | // Note: this loop is unrolled with -O1 and above. | ||||
31 | template<typename T> | ||||
32 | inline void WriteBigEndian(char buf[], T val) { | ||||
33 | for (size_t i = 0; i < sizeof(T); ++i) { | ||||
34 | buf[sizeof(T)-i-1] = static_cast<char>(val & 0xFF); | ||||
35 | val >>= 8; | ||||
36 | } | ||||
37 | } | ||||
38 | |||||
39 | // Specializations to make clang happy about the (dead code) shifts above. | ||||
40 | template<> | ||||
41 | inline void ReadBigEndian<uint8>(const char buf[], uint8* out) { | ||||
42 | *out = buf[0]; | ||||
43 | } | ||||
44 | |||||
45 | template<> | ||||
46 | inline void WriteBigEndian<uint8>(char buf[], uint8 val) { | ||||
47 | buf[0] = static_cast<char>(val); | ||||
48 | } | ||||
49 | |||||
50 | // Allows reading integers in network order (big endian) while iterating over | ||||
51 | // an underlying buffer. All the reading functions advance the internal pointer. | ||||
[email protected] | d9806a9 | 2014-02-26 18:14:57 | [diff] [blame] | 52 | class BASE_EXPORT BigEndianReader { |
[email protected] | 7556ea2 | 2011-12-08 19:29:15 | [diff] [blame] | 53 | public: |
[email protected] | d9806a9 | 2014-02-26 18:14:57 | [diff] [blame] | 54 | BigEndianReader(const char* buf, size_t len); |
[email protected] | 7556ea2 | 2011-12-08 19:29:15 | [diff] [blame] | 55 | |
56 | const char* ptr() const { return ptr_; } | ||||
57 | int remaining() const { return end_ - ptr_; } | ||||
58 | |||||
59 | bool Skip(size_t len); | ||||
60 | bool ReadBytes(void* out, size_t len); | ||||
61 | // Creates a StringPiece in |out| that points to the underlying buffer. | ||||
62 | bool ReadPiece(base::StringPiece* out, size_t len); | ||||
63 | bool ReadU8(uint8* value); | ||||
64 | bool ReadU16(uint16* value); | ||||
65 | bool ReadU32(uint32* value); | ||||
[email protected] | 0d5590f | 2014-07-30 23:24:48 | [diff] [blame] | 66 | bool ReadU64(uint64* value); |
[email protected] | 7556ea2 | 2011-12-08 19:29:15 | [diff] [blame] | 67 | |
68 | private: | ||||
69 | // Hidden to promote type safety. | ||||
70 | template<typename T> | ||||
71 | bool Read(T* v); | ||||
72 | |||||
73 | const char* ptr_; | ||||
74 | const char* end_; | ||||
75 | }; | ||||
76 | |||||
77 | // Allows writing integers in network order (big endian) while iterating over | ||||
78 | // an underlying buffer. All the writing functions advance the internal pointer. | ||||
[email protected] | d9806a9 | 2014-02-26 18:14:57 | [diff] [blame] | 79 | class BASE_EXPORT BigEndianWriter { |
[email protected] | 7556ea2 | 2011-12-08 19:29:15 | [diff] [blame] | 80 | public: |
[email protected] | d9806a9 | 2014-02-26 18:14:57 | [diff] [blame] | 81 | BigEndianWriter(char* buf, size_t len); |
[email protected] | 7556ea2 | 2011-12-08 19:29:15 | [diff] [blame] | 82 | |
83 | char* ptr() const { return ptr_; } | ||||
84 | int remaining() const { return end_ - ptr_; } | ||||
85 | |||||
86 | bool Skip(size_t len); | ||||
87 | bool WriteBytes(const void* buf, size_t len); | ||||
88 | bool WriteU8(uint8 value); | ||||
89 | bool WriteU16(uint16 value); | ||||
90 | bool WriteU32(uint32 value); | ||||
[email protected] | 0d5590f | 2014-07-30 23:24:48 | [diff] [blame] | 91 | bool WriteU64(uint64 value); |
[email protected] | 7556ea2 | 2011-12-08 19:29:15 | [diff] [blame] | 92 | |
93 | private: | ||||
94 | // Hidden to promote type safety. | ||||
95 | template<typename T> | ||||
96 | bool Write(T v); | ||||
97 | |||||
98 | char* ptr_; | ||||
99 | char* end_; | ||||
100 | }; | ||||
101 | |||||
[email protected] | d9806a9 | 2014-02-26 18:14:57 | [diff] [blame] | 102 | } // namespace base |
[email protected] | 7556ea2 | 2011-12-08 19:29:15 | [diff] [blame] | 103 | |
[email protected] | d9806a9 | 2014-02-26 18:14:57 | [diff] [blame] | 104 | #endif // BASE_BIG_ENDIAN_H_ |