kc3-lang/brotli/java/dec/HuffmanTreeGroup.java

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• Hash : 5025365d
  Author :
  Date : 2016-10-17T14:04:59
  

  Add Java port of Brotli decoder.
  

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• java/dec/HuffmanTreeGroup.java

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

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