1 // Copyright 2017 The Chromium OS 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 #ifndef _BSDIFF_COMPRESSOR_BUFFER_H_ 6 #define _BSDIFF_COMPRESSOR_BUFFER_H_ 7 8 #include <stddef.h> 9 #include <stdint.h> 10 11 #include <vector> 12 13 namespace bsdiff { 14 15 // An utility class to store the output from a compressor. It has a small 16 // temporary buffer that holds the compressed data every time the compressed 17 // stream has some output. That buffer is then appended to a list of vectors 18 // stored in memory. This approach is more efficient than a simple vector 19 // because it saves some resize / reallocation of memory. And the compressed 20 // data is copied once no matter how many times we fetch output from the 21 // compressor. 22 class CompressorBuffer { 23 public: 24 explicit CompressorBuffer(size_t buffer_size) { 25 comp_buffer_.resize(buffer_size); 26 } 27 28 size_t buffer_size() { return comp_buffer_.size(); } 29 uint8_t* buffer_data() { return comp_buffer_.data(); } 30 31 // Concatenate the data in |comp_chunks_| and return the data in the form of 32 // a single vector. 33 const std::vector<uint8_t>& GetCompressedData(); 34 35 // Add the data in |comp_buffer_| to the end of |comp_chunks_|. 36 void AddDataToChunks(size_t data_size); 37 38 private: 39 // A list of chunks of compressed data. The final compressed representation is 40 // the concatenation of all the compressed data. 41 std::vector<std::vector<uint8_t>> comp_chunks_; 42 43 // A concatenated version of the |comp_chunks_|, used to store the compressed 44 // memory after Finish() is called. 45 std::vector<uint8_t> comp_data_; 46 47 // A temporary compression buffer for multiple calls to Write(). 48 std::vector<uint8_t> comp_buffer_; 49 }; 50 51 } // namespace bsdiff 52 53 #endif // _BSDIFF_COMPRESSOR_BUFFER_H_ 54
