bzip2/BZip2Constants.java at master · MateuszBartosiewicz/bzip2 · GitHub

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/*
 * Copyright (c) 2011 Matthew Francis
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

package org.itadaki.bzip2;


/**
 * BZip2 constants shared between the compressor and decompressor
 */
interface BZip2Constants {

	/**
	 * First three bytes of the block header marker
	 */
	static final int BLOCK_HEADER_MARKER_1 = 0x314159;

	/**
	 * Last three bytes of the block header marker
	 */
	static final int BLOCK_HEADER_MARKER_2 = 0x265359;

	/**
	 * Number of symbols decoded after which a new Huffman table is selected
	 */
	static final int HUFFMAN_GROUP_RUN_LENGTH = 50;

	/**
	 * Maximum possible Huffman alphabet size
	 */
	static final int HUFFMAN_MAXIMUM_ALPHABET_SIZE = 258;

	/**
	 * The longest Huffman code length created by the encoder
	 */
	static final int HUFFMAN_ENCODE_MAXIMUM_CODE_LENGTH = 20;

	/**
	 * The longest Huffman code length accepted by the decoder
	 */
	static final int HUFFMAN_DECODE_MAXIMUM_CODE_LENGTH = 23;

	/**
	 * Minimum number of alternative Huffman tables
	 */
	static final int HUFFMAN_MINIMUM_TABLES = 2;

	/**
	 * Maximum number of alternative Huffman tables
	 */
	static final int HUFFMAN_MAXIMUM_TABLES = 6;

	/**
	 * Maximum possible number of Huffman table selectors
	 */
	static final int HUFFMAN_MAXIMUM_SELECTORS = (900000 / HUFFMAN_GROUP_RUN_LENGTH) + 1;

	/**
	 * Huffman symbol used for run-length encoding
	 */
	static final int HUFFMAN_SYMBOL_RUNA = 0;

	/**
	 * Huffman symbol used for run-length encoding
	 */
	static final int HUFFMAN_SYMBOL_RUNB = 1;

	/**
	 * First three bytes of the end of stream marker
	 */
	static final int STREAM_END_MARKER_1 = 0x177245;

	/**
	 * Last three bytes of the end of stream marker
	 */
	static final int STREAM_END_MARKER_2 = 0x385090;

	/**
	 * 'B' 'Z' that marks the start of a BZip2 stream
	 */
	static final int STREAM_START_MARKER_1 = 0x425a;

	/**
	 * 'h' that distinguishes BZip from BZip2
	 */
	static final int STREAM_START_MARKER_2 = 0x68;

}