61 lines
1.8 KiB
C++
61 lines
1.8 KiB
C++
// Copyright 2017 Google Inc. All rights reserved.
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//
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file or at
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// https://developers.google.com/open-source/licenses/bsd
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#ifndef PACKAGER_MEDIA_BASE_BIT_WRITER_H_
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#define PACKAGER_MEDIA_BASE_BIT_WRITER_H_
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#include <stdint.h>
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#include <vector>
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#include "packager/base/logging.h"
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namespace shaka {
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namespace media {
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class BitWriter {
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public:
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/// Constructor a BitWriter instance which writes to the provided storage.
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/// @param storage points to vector this BitWriter writes to. Cannot be
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/// nullptr.
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explicit BitWriter(std::vector<uint8_t>* storage);
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~BitWriter() = default;
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/// Appends the sequence 'bits' of length 'number_of_bits' <= 32.
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/// Note that 'bits' should contain at most 'number_of_bits' bits, i.e.
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/// bits should be less than 1 << number_of_bits.
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/// @param bits is the data to write.
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/// @param number_of_bits is the number of LSB to write, capped at 32. Cannot
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/// be zero.
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void WriteBits(uint32_t bits, size_t number_of_bits);
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/// Write pending bits, and align bitstream with extra zero bits.
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void Flush();
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/// @return last written position, in bits.
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size_t BitPos() const { return BytePos() * 8 + num_bits_; }
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/// @return last written position, in bytes.
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size_t BytePos() const { return storage_->size() - initial_storage_size_; }
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private:
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BitWriter(const BitWriter&) = delete;
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BitWriter& operator=(const BitWriter&) = delete;
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// Accumulator for unwritten bits.
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uint64_t bits_ = 0;
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// Number of unwritten bits.
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int num_bits_ = 0;
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// Buffer contains the written bits.
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std::vector<uint8_t>* const storage_ = nullptr;
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const size_t initial_storage_size_ = 0;
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};
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} // namespace media
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} // namespace shaka
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#endif // PACKAGER_MEDIA_BASE_BIT_WRITER_H_
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