/*
* 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:
*
* http://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;
/**
* Constants for both the {@link Bzip2Encoder} and the {@link Bzip2Decoder}.
*/
final class Bzip2Constants {
/**
* Magic number of Bzip2 stream.
*/
static final int MAGIC_NUMBER = 'B' << 16 | 'Z' << 8 | 'h';
/**
* Block header magic number. Equals to BCD (pi).
*/
static final int BLOCK_HEADER_MAGIC_1 = 0x314159;
static final int BLOCK_HEADER_MAGIC_2 = 0x265359;
/**
* End of stream magic number. Equals to BCD sqrt(pi).
*/
static final int END_OF_STREAM_MAGIC_1 = 0x177245;
static final int END_OF_STREAM_MAGIC_2 = 0x385090;
/**
* Base block size.
*/
static final int BASE_BLOCK_SIZE = 100000;
/**
* Minimum and maximum size of one block.
* Must be multiplied by {@link Bzip2Constants#BASE_BLOCK_SIZE}.
*/
static final int MIN_BLOCK_SIZE = 1;
static final int MAX_BLOCK_SIZE = 9;
/**
* Maximum possible Huffman alphabet size.
*/
static final int HUFFMAN_MAX_ALPHABET_SIZE = 258;
/**
* The longest Huffman code length created by the encoder.
*/
static final int HUFFMAN_ENCODE_MAX_CODE_LENGTH = 20;
/**
* The longest Huffman code length accepted by the decoder.
*/
static final int HUFFMAN_DECODE_MAX_CODE_LENGTH = 23;
/**
* Huffman symbols used for run-length encoding.
*/
static final int HUFFMAN_SYMBOL_RUNA = 0;
static final int HUFFMAN_SYMBOL_RUNB = 1;
/**
* Huffman symbols range size for Huffman used map.
*/
static final int HUFFMAN_SYMBOL_RANGE_SIZE = 16;
/**
* Maximum length of zero-terminated bit runs of MTF'ed Huffman table.
*/
static final int HUFFMAN_SELECTOR_LIST_MAX_LENGTH = 6;
/**
* Number of symbols decoded after which a new Huffman table is selected.
*/
static final int HUFFMAN_GROUP_RUN_LENGTH = 50;
/**
* Maximum possible number of Huffman table selectors.
*/
static final int MAX_SELECTORS = 2 + 900000 / HUFFMAN_GROUP_RUN_LENGTH; // 18002
/**
* 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;
private Bzip2Constants() { }
}