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1 // Copyright 2014 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 // LEB128 encoder and decoder for packed R_ARM_RELATIVE relocations. | |
6 // | |
7 // Run-length encoded R_ARM_RELATIVE relocations consist of a large number | |
8 // of pairs of relatively small positive integer values. Encoding these as | |
9 // LEB128 saves space. | |
10 // | |
11 // For more on LEB128 see http://en.wikipedia.org/wiki/LEB128. | |
12 | |
13 #ifndef TOOLS_RELOCATION_PACKER_SRC_LEB128_H_ | |
14 #define TOOLS_RELOCATION_PACKER_SRC_LEB128_H_ | |
15 | |
16 #include <stdint.h> | |
17 #include <unistd.h> | |
18 #include <vector> | |
19 | |
20 namespace relocation_packer { | |
21 | |
22 // Encode packed words as a LEB128 byte stream. | |
23 class Leb128Encoder { | |
24 public: | |
25 // Add a value or a vector of values to the encoding stream. | |
26 // |value| is the unsigned int to add. | |
27 void Enqueue(uint32_t value); | |
rmcilroy
2014/06/07 11:49:07
Newline
simonb (inactive)
2014/06/09 14:39:19
Done.
| |
28 // |values| is the vector of unsigned ints to add. | |
29 void EnqueueAll(const std::vector<uint32_t>& values); | |
30 | |
31 // Retrieve the encoded representation of the values. | |
32 // |encoding| is the returned vector of encoded data. | |
33 void GetEncoding(std::vector<uint8_t>* encoding) { *encoding = encoding_; } | |
34 | |
35 private: | |
36 // Growable vector holding the encoded LEB128 stream. | |
37 std::vector<uint8_t> encoding_; | |
38 }; | |
39 | |
40 // Decode a LEB128 byte stream to produce packed words. | |
41 class Leb128Decoder { | |
42 public: | |
43 // Create a new decoder for the given encoded stream. | |
44 // |encoding| is the vector of encoded data. | |
45 explicit Leb128Decoder(const std::vector<uint8_t>& encoding) | |
46 : encoding_(encoding), cursor_(0) { } | |
47 | |
48 // Retrieve the next value from the encoded stream. | |
49 uint32_t Dequeue(); | |
50 | |
51 // Retrieve all remaining values from the encoded stream. | |
52 // |values| is the vector of decoded data. | |
53 void DequeueAll(std::vector<uint32_t>* values); | |
54 | |
55 private: | |
56 // Encoded LEB128 stream. | |
57 std::vector<uint8_t> encoding_; | |
58 | |
59 // Cursor indicating the current stream retrieval point. | |
60 size_t cursor_; | |
61 }; | |
62 | |
63 } // namespace relocation_packer | |
64 | |
65 #endif // TOOLS_RELOCATION_PACKER_SRC_LEB128_H_ | |
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