mirror of
https://github.com/LadybirdBrowser/ladybird.git
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244 lines
6.1 KiB
C++
244 lines
6.1 KiB
C++
/*
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* Copyright (c) 2020, the SerenityOS developers.
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* Copyright (c) 2021, Idan Horowitz <idan.horowitz@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#pragma once
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#include <AK/Optional.h>
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#include <AK/Stream.h>
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namespace AK {
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// Obsoleted by LibCore/{Big, Little}EndianInputBitStream.
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class InputBitStream final : public InputStream {
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public:
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explicit InputBitStream(InputStream& stream)
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: m_stream(stream)
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{
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}
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size_t read(Bytes bytes) override
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{
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if (has_any_error())
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return 0;
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size_t nread = 0;
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if (bytes.size() >= 1) {
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if (m_next_byte.has_value()) {
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bytes[0] = m_next_byte.value();
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m_next_byte.clear();
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++nread;
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}
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}
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return nread + m_stream.read(bytes.slice(nread));
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}
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bool read_or_error(Bytes bytes) override
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{
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if (read(bytes) != bytes.size()) {
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set_fatal_error();
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return false;
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}
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return true;
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}
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bool unreliable_eof() const override { return !m_next_byte.has_value() && m_stream.unreliable_eof(); }
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bool discard_or_error(size_t count) override
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{
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if (count >= 1) {
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if (m_next_byte.has_value()) {
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m_next_byte.clear();
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--count;
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}
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}
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return m_stream.discard_or_error(count);
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}
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u64 read_bits(size_t count)
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{
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u64 result = 0;
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size_t nread = 0;
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while (nread < count) {
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if (m_stream.has_any_error()) {
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set_fatal_error();
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return 0;
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}
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if (m_next_byte.has_value()) {
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auto const bit = (m_next_byte.value() >> m_bit_offset) & 1;
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result |= bit << nread;
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++nread;
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if (m_bit_offset++ == 7)
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m_next_byte.clear();
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} else {
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m_stream >> m_next_byte;
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m_bit_offset = 0;
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}
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}
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return result;
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}
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u64 read_bits_big_endian(size_t count)
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{
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u64 result = 0;
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size_t nread = 0;
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while (nread < count) {
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if (m_stream.has_any_error()) {
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set_fatal_error();
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return 0;
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}
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if (m_next_byte.has_value()) {
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// read an entire byte
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if (((count - nread) >= 8) && m_bit_offset == 0) {
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// shift existing bytes over
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result <<= 8;
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result |= m_next_byte.value();
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nread += 8;
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m_next_byte.clear();
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} else {
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auto const bit = (m_next_byte.value() >> (7 - m_bit_offset)) & 1;
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result <<= 1;
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result |= bit;
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++nread;
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if (m_bit_offset++ == 7)
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m_next_byte.clear();
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}
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} else {
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m_stream >> m_next_byte;
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m_bit_offset = 0;
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}
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}
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return result;
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}
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bool read_bit() { return static_cast<bool>(read_bits(1)); }
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bool read_bit_big_endian() { return static_cast<bool>(read_bits_big_endian(1)); }
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void align_to_byte_boundary()
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{
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if (m_next_byte.has_value())
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m_next_byte.clear();
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}
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bool handle_any_error() override
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{
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bool handled_errors = m_stream.handle_any_error();
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return Stream::handle_any_error() || handled_errors;
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}
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private:
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Optional<u8> m_next_byte;
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size_t m_bit_offset { 0 };
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InputStream& m_stream;
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};
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class OutputBitStream final : public OutputStream {
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public:
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explicit OutputBitStream(OutputStream& stream)
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: m_stream(stream)
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{
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}
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// WARNING: write aligns to the next byte boundary before writing, if unaligned writes are needed this should be rewritten
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size_t write(ReadonlyBytes bytes) override
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{
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if (has_any_error())
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return 0;
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align_to_byte_boundary();
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if (has_fatal_error()) // if align_to_byte_boundary failed
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return 0;
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return m_stream.write(bytes);
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}
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bool write_or_error(ReadonlyBytes bytes) override
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{
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if (write(bytes) < bytes.size()) {
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set_fatal_error();
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return false;
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}
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return true;
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}
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void write_bits(u32 bits, size_t count)
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{
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VERIFY(count <= 32);
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if (count == 32 && !m_next_byte.has_value()) { // fast path for aligned 32 bit writes
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m_stream << bits;
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return;
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}
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size_t n_written = 0;
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while (n_written < count) {
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if (m_stream.has_any_error()) {
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set_fatal_error();
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return;
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}
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if (m_next_byte.has_value()) {
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m_next_byte.value() |= ((bits >> n_written) & 1) << m_bit_offset;
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++n_written;
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if (m_bit_offset++ == 7) {
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m_stream << m_next_byte.value();
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m_next_byte.clear();
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}
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} else if (count - n_written >= 16) { // fast path for aligned 16 bit writes
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m_stream << (u16)((bits >> n_written) & 0xFFFF);
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n_written += 16;
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} else if (count - n_written >= 8) { // fast path for aligned 8 bit writes
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m_stream << (u8)((bits >> n_written) & 0xFF);
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n_written += 8;
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} else {
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m_bit_offset = 0;
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m_next_byte = 0;
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}
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}
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}
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void write_bit(bool bit)
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{
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write_bits(bit, 1);
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}
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void align_to_byte_boundary()
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{
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if (m_next_byte.has_value()) {
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if (!m_stream.write_or_error(ReadonlyBytes { &m_next_byte.value(), 1 })) {
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set_fatal_error();
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}
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m_next_byte.clear();
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}
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}
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size_t bit_offset() const
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{
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return m_bit_offset;
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}
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private:
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Optional<u8> m_next_byte;
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size_t m_bit_offset { 0 };
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OutputStream& m_stream;
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};
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}
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using AK::InputBitStream;
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using AK::OutputBitStream;
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