Bzip2BlockDecompressor.java — netty Source File

Source Code

/*
 * Copyright 2014 The Netty Project
 *
 * The Netty Project licenses this file to you under the Apache License,
 * version 2.0 (the "License"); you may not use this file except in compliance
 * with the License. You may obtain a copy of the License at:
 *
 *   https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations
 * under the License.
 */
package io.netty.handler.codec.compression;

import static io.netty.handler.codec.compression.Bzip2Constants.HUFFMAN_DECODE_MAX_CODE_LENGTH;
import static io.netty.handler.codec.compression.Bzip2Constants.HUFFMAN_SYMBOL_RUNA;
import static io.netty.handler.codec.compression.Bzip2Constants.HUFFMAN_SYMBOL_RUNB;
import static io.netty.handler.codec.compression.Bzip2Constants.MAX_BLOCK_LENGTH;

/**
 * Reads and decompresses a single Bzip2 block.<br><br>
 *
 * Block decoding consists of the following stages:<br>
 * 1. Read block header<br>
 * 2. Read Huffman tables<br>
 * 3. Read and decode Huffman encoded data - {@link #decodeHuffmanData(Bzip2HuffmanStageDecoder)}<br>
 * 4. Run-Length Decoding[2] - {@link #decodeHuffmanData(Bzip2HuffmanStageDecoder)}<br>
 * 5. Inverse Move To Front Transform - {@link #decodeHuffmanData(Bzip2HuffmanStageDecoder)}<br>
 * 6. Inverse Burrows Wheeler Transform - {@link #initialiseInverseBWT()}<br>
 * 7. Run-Length Decoding[1] - {@link #read()}<br>
 * 8. Optional Block De-Randomisation - {@link #read()} (through {@link #decodeNextBWTByte()})
 */
final class Bzip2BlockDecompressor {
    /**
     * A reader that provides bit-level reads.
     */
    private final Bzip2BitReader reader;

    /**
     * Calculates the block CRC from the fully decoded bytes of the block.
     */
    private final Crc32 crc = new Crc32();

    /**
     * The CRC of the current block as read from the block header.
     */
    private final int blockCRC;

    /**
     * {@code true} if the current block is randomised, otherwise {@code false}.
     */
    private final boolean blockRandomised;

    /* Huffman Decoding stage */
    /**
     * The end-of-block Huffman symbol. Decoding of the block ends when this is encountered.
     */
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