xref: /external/brotli/java/org/brotli/dec/Prefix.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;

/**
 * Lookup tables to map prefix codes to value ranges.
 *
 * <p> This is used during decoding of the block lengths, literal insertion lengths and copy
 * lengths.
 *
 * <p> Range represents values: [offset, offset + 2 ^ n_bits)
 */
final class Prefix {

  static final int[] BLOCK_LENGTH_OFFSET = {
      1, 5, 9, 13, 17, 25, 33, 41, 49, 65, 81, 97, 113, 145, 177, 209, 241, 305, 369, 497,
      753, 1265, 2289, 4337, 8433, 16625
  };

  static final int[] BLOCK_LENGTH_N_BITS = {
      2, 2, 2, 2, 3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 6, 6, 7, 8, 9, 10, 11, 12, 13, 24
  };

  static final int[] INSERT_LENGTH_OFFSET = {
      0, 1, 2, 3, 4, 5, 6, 8, 10, 14, 18, 26, 34, 50, 66, 98, 130, 194, 322, 578, 1090, 2114, 6210,
      22594
  };

  static final int[] INSERT_LENGTH_N_BITS = {
      0, 0, 0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 7, 8, 9, 10, 12, 14, 24
  };

  static final int[] COPY_LENGTH_OFFSET = {
      2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 18, 22, 30, 38, 54, 70, 102, 134, 198, 326, 582, 1094,
      2118
  };

  static final int[] COPY_LENGTH_N_BITS = {
      0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 7, 8, 9, 10, 24
  };

  static final int[] INSERT_RANGE_LUT = {
      0, 0, 8, 8, 0, 16, 8, 16, 16
  };

  static final int[] COPY_RANGE_LUT = {
      0, 8, 0, 8, 16, 0, 16, 8, 16
  };
}