1 /* Copyright 2015 Google Inc. All Rights Reserved. 2 3 Distributed under MIT license. 4 See file LICENSE for detail or copy at https://opensource.org/licenses/MIT 5 */ 6 7 package org.brotli.dec; 8 9 /** 10 * Common context lookup table for all context modes. 11 */ 12 final class Context { 13 14 static final int[] LOOKUP = new int[2048]; 15 16 private static final String UTF_MAP = " !! ! \"#$##%#$&'##(#)#+++++++++" 17 + "+((&*'##,---,---,-----,-----,-----&#'###.///.///./////./////./////&#'# "; 18 private static final String UTF_RLE = "A/* ': & : $ \u0081 @"; 19 20 private static void unpackLookupTable(int[] lookup, String map, String rle) { 21 // LSB6, MSB6, SIGNED 22 for (int i = 0; i < 256; ++i) { 23 lookup[i] = i & 0x3F; 24 lookup[512 + i] = i >> 2; 25 lookup[1792 + i] = 2 + (i >> 6); 26 } 27 // UTF8 28 for (int i = 0; i < 128; ++i) { 29 lookup[1024 + i] = 4 * (map.charAt(i) - 32); 30 } 31 for (int i = 0; i < 64; ++i) { 32 lookup[1152 + i] = i & 1; 33 lookup[1216 + i] = 2 + (i & 1); 34 } 35 int offset = 1280; 36 for (int k = 0; k < 19; ++k) { 37 int value = k & 3; 38 int rep = rle.charAt(k) - 32; 39 for (int i = 0; i < rep; ++i) { 40 lookup[offset++] = value; 41 } 42 } 43 // SIGNED 44 for (int i = 0; i < 16; ++i) { 45 lookup[1792 + i] = 1; 46 lookup[2032 + i] = 6; 47 } 48 lookup[1792] = 0; 49 lookup[2047] = 7; 50 for (int i = 0; i < 256; ++i) { 51 lookup[1536 + i] = lookup[1792 + i] << 3; 52 } 53 } 54 55 static { 56 unpackLookupTable(LOOKUP, UTF_MAP, UTF_RLE); 57 } 58 } 59
