1 /* 2 * LZMACoder 3 * 4 * Authors: Lasse Collin <lasse.collin@tukaani.org> 5 * Igor Pavlov <http://7-zip.org/> 6 * 7 * This file has been put into the public domain. 8 * You can do whatever you want with this file. 9 */ 10 11 package org.tukaani.xz.lzma; 12 13 import org.tukaani.xz.rangecoder.RangeCoder; 14 15 abstract class LZMACoder { 16 static final int POS_STATES_MAX = 1 << 4; 17 18 static final int MATCH_LEN_MIN = 2; 19 static final int MATCH_LEN_MAX = MATCH_LEN_MIN + LengthCoder.LOW_SYMBOLS 20 + LengthCoder.MID_SYMBOLS 21 + LengthCoder.HIGH_SYMBOLS - 1; 22 23 static final int DIST_STATES = 4; 24 static final int DIST_SLOTS = 1 << 6; 25 static final int DIST_MODEL_START = 4; 26 static final int DIST_MODEL_END = 14; 27 static final int FULL_DISTANCES = 1 << (DIST_MODEL_END / 2); 28 29 static final int ALIGN_BITS = 4; 30 static final int ALIGN_SIZE = 1 << ALIGN_BITS; 31 static final int ALIGN_MASK = ALIGN_SIZE - 1; 32 33 static final int REPS = 4; 34 35 final int posMask; 36 37 final int[] reps = new int[REPS]; 38 final State state = new State(); 39 40 final short[][] isMatch = new short[State.STATES][POS_STATES_MAX]; 41 final short[] isRep = new short[State.STATES]; 42 final short[] isRep0 = new short[State.STATES]; 43 final short[] isRep1 = new short[State.STATES]; 44 final short[] isRep2 = new short[State.STATES]; 45 final short[][] isRep0Long = new short[State.STATES][POS_STATES_MAX]; 46 final short[][] distSlots = new short[DIST_STATES][DIST_SLOTS]; 47 final short[][] distSpecial = { new short[2], new short[2], 48 new short[4], new short[4], 49 new short[8], new short[8], 50 new short[16], new short[16], 51 new short[32], new short[32] }; 52 final short[] distAlign = new short[ALIGN_SIZE]; 53 getDistState(int len)54 static final int getDistState(int len) { 55 return len < DIST_STATES + MATCH_LEN_MIN 56 ? len - MATCH_LEN_MIN 57 : DIST_STATES - 1; 58 } 59 LZMACoder(int pb)60 LZMACoder(int pb) { 61 posMask = (1 << pb) - 1; 62 } 63 reset()64 void reset() { 65 reps[0] = 0; 66 reps[1] = 0; 67 reps[2] = 0; 68 reps[3] = 0; 69 state.reset(); 70 71 for (int i = 0; i < isMatch.length; ++i) 72 RangeCoder.initProbs(isMatch[i]); 73 74 RangeCoder.initProbs(isRep); 75 RangeCoder.initProbs(isRep0); 76 RangeCoder.initProbs(isRep1); 77 RangeCoder.initProbs(isRep2); 78 79 for (int i = 0; i < isRep0Long.length; ++i) 80 RangeCoder.initProbs(isRep0Long[i]); 81 82 for (int i = 0; i < distSlots.length; ++i) 83 RangeCoder.initProbs(distSlots[i]); 84 85 for (int i = 0; i < distSpecial.length; ++i) 86 RangeCoder.initProbs(distSpecial[i]); 87 88 RangeCoder.initProbs(distAlign); 89 } 90 91 92 abstract class LiteralCoder { 93 private final int lc; 94 private final int literalPosMask; 95 LiteralCoder(int lc, int lp)96 LiteralCoder(int lc, int lp) { 97 this.lc = lc; 98 this.literalPosMask = (1 << lp) - 1; 99 } 100 getSubcoderIndex(int prevByte, int pos)101 final int getSubcoderIndex(int prevByte, int pos) { 102 int low = prevByte >> (8 - lc); 103 int high = (pos & literalPosMask) << lc; 104 return low + high; 105 } 106 107 108 abstract class LiteralSubcoder { 109 final short[] probs = new short[0x300]; 110 reset()111 void reset() { 112 RangeCoder.initProbs(probs); 113 } 114 } 115 } 116 117 118 abstract class LengthCoder { 119 static final int LOW_SYMBOLS = 1 << 3; 120 static final int MID_SYMBOLS = 1 << 3; 121 static final int HIGH_SYMBOLS = 1 << 8; 122 123 final short[] choice = new short[2]; 124 final short[][] low = new short[POS_STATES_MAX][LOW_SYMBOLS]; 125 final short[][] mid = new short[POS_STATES_MAX][MID_SYMBOLS]; 126 final short[] high = new short[HIGH_SYMBOLS]; 127 reset()128 void reset() { 129 RangeCoder.initProbs(choice); 130 131 for (int i = 0; i < low.length; ++i) 132 RangeCoder.initProbs(low[i]); 133 134 for (int i = 0; i < low.length; ++i) 135 RangeCoder.initProbs(mid[i]); 136 137 RangeCoder.initProbs(high); 138 } 139 } 140 } 141