mirror of https://github.com/google/brotli
58 lines
1.4 KiB
Java
58 lines
1.4 KiB
Java
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/* Copyright 2015 Google Inc. All Rights Reserved.
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Distributed under MIT license.
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See file LICENSE for detail or copy at https://opensource.org/licenses/MIT
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*/
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package org.brotli.dec;
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/**
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* Contains a collection of huffman trees with the same alphabet size.
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*/
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final class HuffmanTreeGroup {
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/**
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* The maximal alphabet size in this group.
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*/
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private int alphabetSize;
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/**
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* Storage for Huffman lookup tables.
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*/
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int[] codes;
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/**
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* Offsets of distinct lookup tables in {@link #codes} storage.
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*/
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int[] trees;
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/**
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* Initializes the Huffman tree group.
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*
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* @param group POJO to be initialised
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* @param alphabetSize the maximal alphabet size in this group
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* @param n number of Huffman codes
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*/
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static void init(HuffmanTreeGroup group, int alphabetSize, int n) {
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group.alphabetSize = alphabetSize;
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group.codes = new int[n * Huffman.HUFFMAN_MAX_TABLE_SIZE];
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group.trees = new int[n];
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}
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/**
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* Decodes Huffman trees from input stream and constructs lookup tables.
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*
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* @param group target POJO
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* @param br data source
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*/
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static void decode(HuffmanTreeGroup group, BitReader br) {
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int next = 0;
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int n = group.trees.length;
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for (int i = 0; i < n; i++) {
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group.trees[i] = next;
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Decode.readHuffmanCode(group.alphabetSize, group.codes, next, br);
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next += Huffman.HUFFMAN_MAX_TABLE_SIZE;
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}
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}
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}
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