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// Copyright 2017 The Chromium OS Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef _BSDIFF_COMPRESSOR_BUFFER_H_
#define _BSDIFF_COMPRESSOR_BUFFER_H_
#include <stddef.h>
#include <stdint.h>
#include <vector>
namespace bsdiff {
// An utility class to store the output from a compressor. It has a small
// temporary buffer that holds the compressed data every time the compressed
// stream has some output. That buffer is then appended to a list of vectors
// stored in memory. This approach is more efficient than a simple vector
// because it saves some resize / reallocation of memory. And the compressed
// data is copied once no matter how many times we fetch output from the
// compressor.
class CompressorBuffer {
public:
explicit CompressorBuffer(size_t buffer_size) {
comp_buffer_.resize(buffer_size);
}
size_t buffer_size() { return comp_buffer_.size(); }
uint8_t* buffer_data() { return comp_buffer_.data(); }
// Concatenate the data in |comp_chunks_| and return the data in the form of
// a single vector.
const std::vector<uint8_t>& GetCompressedData();
// Add the data in |comp_buffer_| to the end of |comp_chunks_|.
void AddDataToChunks(size_t data_size);
private:
// A list of chunks of compressed data. The final compressed representation is
// the concatenation of all the compressed data.
std::vector<std::vector<uint8_t>> comp_chunks_;
// A concatenated version of the |comp_chunks_|, used to store the compressed
// memory after Finish() is called.
std::vector<uint8_t> comp_data_;
// A temporary compression buffer for multiple calls to Write().
std::vector<uint8_t> comp_buffer_;
};
} // namespace bsdiff
#endif // _BSDIFF_COMPRESSOR_BUFFER_H_
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