modelppm.java

这是架包java-unrar-0.2.jar的源码

/*
 * Copyright (c) 2007 innoSysTec (R) GmbH, Germany. All rights reserved.
 * Original author: Edmund Wagner
 * Creation date: 31.05.2007
 *
 * Source: $HeadURL$
 * Last changed: $LastChangedDate$
 * 
 * the unrar licence applies to all junrar source and binary distributions 
 * you are not allowed to use this source to re-create the RAR compression algorithm
 * 
 * Here some html entities which can be used for escaping javadoc tags:
 * "&":  "&" or "&"
 * "<":  "&#060;" or "&lt;"
 * ">":  "&#062;" or "&gt;"
 * "@":  "&#064;" 
 */
package de.innosystec.unrar.unpack.ppm;

import java.io.IOException;
import java.util.Arrays;

import de.innosystec.unrar.exception.RarException;
import de.innosystec.unrar.unpack.Unpack;

/**
 * DOCUMENT ME
 * 
 * @author $LastChangedBy$
 * @version $LastChangedRevision$
 */
public class ModelPPM
{
	public static final int MAX_O = 64; /* maximum allowed model order */

	public static final int INT_BITS = 7;

	public static final int PERIOD_BITS = 7;

	public static final int TOT_BITS = INT_BITS + PERIOD_BITS;

	public static final int INTERVAL = 1 << INT_BITS;

	public static final int BIN_SCALE = 1 << TOT_BITS;

	public static final int MAX_FREQ = 124;

	private SEE2Context[][] SEE2Cont = new SEE2Context[25][16];

	private SEE2Context dummySEE2Cont;

	private PPMContext minContext, medContext, maxContext;

	private State foundState; // found next state transition

	private int numMasked, initEsc, orderFall, maxOrder, runLength, initRL;

	private int[] charMask = new int[256];

	private int[] NS2Indx = new int[256];

	private int[] NS2BSIndx = new int[256];

	private int[] HB2Flag = new int[256];

    // byte EscCount, PrevSuccess, HiBitsFlag;
	private int escCount, prevSuccess, hiBitsFlag;

	private int[][] binSumm = new int[128][64]; // binary SEE-contexts

	private RangeCoder coder = new RangeCoder();

	private SubAllocator subAlloc = new SubAllocator();

	private static int InitBinEsc[] = { 0x3CDD, 0x1F3F, 0x59BF, 0x48F3,
			0x64A1, 0x5ABC, 0x6632, 0x6051 };

    // Temp fields
    private final State tempState1 = new State(null);
    private final State tempState2 = new State(null);
    private final State tempState3 = new State(null);
    private final State tempState4 = new State(null);
    private final StateRef tempStateRef1 = new StateRef();
    private final StateRef tempStateRef2 = new StateRef();
    private final PPMContext tempPPMContext1 = new PPMContext(null);
    private final PPMContext tempPPMContext2 = new PPMContext(null);
    private final PPMContext tempPPMContext3 = new PPMContext(null);
    private final PPMContext tempPPMContext4 = new PPMContext(null);
    private final int[] ps = new int[MAX_O];

	public ModelPPM()
	{
		minContext = null;
		maxContext = null;
		medContext = null;
	}

	public SubAllocator getSubAlloc()
	{
		return subAlloc;
	}

	private void restartModelRare()
	{
		Arrays.fill(charMask, 0);
		subAlloc.initSubAllocator();
		initRL = -(maxOrder < 12 ? maxOrder : 12) - 1;
		int addr = subAlloc.allocContext();
		minContext.setAddress(addr);
		maxContext.setAddress(addr);
		minContext.setSuffix(0);
		orderFall = maxOrder;
		minContext.setNumStats(256);
		minContext.getFreqData().setSummFreq(minContext.getNumStats()+1);
				
		addr = subAlloc.allocUnits(256 / 2);
		foundState.setAddress(addr);
		minContext.getFreqData().setStats(addr);

		State state = new State(subAlloc.getHeap());
		addr = minContext.getFreqData().getStats();
        runLength = initRL;
        prevSuccess = 0;
		for (int i = 0; i < 256; i++) {
			state.setAddress(addr + i * State.size);
			state.setSymbol(i);
			state.setFreq(1);
			state.setSuccessor(0);
		}

		for (int i = 0; i < 128; i++) {
			for (int k = 0; k < 8; k++) {
				for (int m = 0; m < 64; m += 8) {
					binSumm[i][k + m] = BIN_SCALE - InitBinEsc[k] / (i + 2);
				}
			}
		}
		for (int i = 0; i < 25; i++) {
			for (int k = 0; k < 16; k++) {
				SEE2Cont[i][k].init(5 * i + 10);
			}
		}
	}

	private void startModelRare(int MaxOrder)
	{
        int i, k, m, Step;
		escCount = 1;
		this.maxOrder = MaxOrder;
		restartModelRare();
        // Bug Fixed
        NS2BSIndx[0] = 0;
        NS2BSIndx[1] = 2;
		for (int j = 0; j < 9; j++) {
			NS2BSIndx[2 + j] = 4;
		}
		for (int j = 0; j < 256 - 11; j++) {
			NS2BSIndx[11 + j] = 6;
		}
		for (i = 0; i < 3; i++) {
			NS2Indx[i] = i;
		}
		for (m = i, k = 1, Step = 1; i < 256; i++) {
			NS2Indx[i] = m;
			if ((--k) == 0) {
				k = ++Step;
				m++;
			}
		}
		for (int j = 0; j < 0x40; j++) {
			HB2Flag[j] = 0;
		}
		for (int j = 0; j < 0x100 - 0x40; j++) {
			HB2Flag[0x40 + j] = 0x08;
		}
		dummySEE2Cont.setShift(PERIOD_BITS);

	}

	private void clearMask()
	{
		escCount = 1;
		Arrays.fill(charMask, 0);
	}

	public boolean decodeInit(Unpack unpackRead, int escChar/* ref */)
			throws IOException, RarException
	{

		int MaxOrder = unpackRead.getChar() & 0xff;
		boolean reset = ((MaxOrder & 0x20) != 0);

		int MaxMB = 0;
		if (reset) {
			MaxMB = unpackRead.getChar();
		} else {
			if (subAlloc.GetAllocatedMemory() == 0) {
				return (false);
			}
		}
		if ((MaxOrder & 0x40) != 0) {
			escChar = unpackRead.getChar();
			unpackRead.setPpmEscChar(escChar);
		}
		coder.initDecoder(unpackRead);
		if (reset) {
			MaxOrder = (MaxOrder & 0x1f) + 1;
			if (MaxOrder > 16) {
				MaxOrder = 16 + (MaxOrder - 16) * 3;
			}
			if (MaxOrder == 1) {
				subAlloc.stopSubAllocator();
				return (false);
			}
			subAlloc.startSubAllocator(MaxMB + 1);
			minContext = new PPMContext(getHeap());
			medContext = new PPMContext(getHeap());
			maxContext = new PPMContext(getHeap());
			foundState = new State(getHeap());
			dummySEE2Cont = new SEE2Context();
			for (int i = 0; i < 25; i++) {
				for (int j = 0; j < 16; j++) {
					SEE2Cont[i][j] = new SEE2Context();
				}
			}
			startModelRare(MaxOrder);
		}
		return (minContext.getAddress() != 0);
	}

	public int decodeChar() throws IOException, RarException
	{
        // Debug
        //subAlloc.dumpHeap();

		if (minContext.getAddress() <= subAlloc.getPText()
				|| minContext.getAddress() > subAlloc.getHeapEnd()) {
			return (-1);
		}

		if (minContext.getNumStats() != 1) {
			if (minContext.getFreqData().getStats() <= subAlloc.getPText()
					|| minContext.getFreqData().getStats() > subAlloc.getHeapEnd()) {
				return (-1);
			}
			if (!minContext.decodeSymbol1(this)) {
				return (-1);
			}
		} else {
			minContext.decodeBinSymbol(this);
		}
		coder.decode();
		while (foundState.getAddress() == 0) {
			coder.ariDecNormalize();
			do {
				orderFall++;
				minContext.setAddress(minContext.getSuffix());// =MinContext->Suffix;
				if (minContext.getAddress() <= subAlloc.getPText()
						|| minContext.getAddress() > subAlloc.getHeapEnd()) {
					return (-1);
				}
			} while (minContext.getNumStats() == numMasked);
			if (!minContext.decodeSymbol2(this)) {
				return (-1);
			}
			coder.decode();
		}
		int Symbol = foundState.getSymbol();
		if ((orderFall == 0) && foundState.getSuccessor() > subAlloc.getPText()) {
			// MinContext=MaxContext=FoundState->Successor;
			int addr = foundState.getSuccessor();
			minContext.setAddress(addr);
			maxContext.setAddress(addr);
		} else {
			updateModel();
			//this.foundState.setAddress(foundState.getAddress());//TODO just 4 debugging
			if (escCount == 0) {
				clearMask();
			}
		}
		coder.ariDecNormalize();// ARI_DEC_NORMALIZE(Coder.code,Coder.low,Coder.range,Coder.UnpackRead);
		return (Symbol);
	}

	public SEE2Context[][] getSEE2Cont()
	{
		return SEE2Cont;
	}

	public SEE2Context getDummySEE2Cont()
	{
		return dummySEE2Cont;
	}

	public int getInitRL()
	{
		return initRL;
	}

	public void setEscCount(int escCount)
	{
		this.escCount = escCount&0xff;
	}

	public int getEscCount()
	{
		return escCount;
	}

    public void incEscCount(int dEscCount) {
        setEscCount(getEscCount() + dEscCount);
    }

	public int[] getCharMask()
	{
		return charMask;
	}

	public int getNumMasked()
	{
		return numMasked;
	}

	public void setNumMasked(int numMasked)
	{
		this.numMasked = numMasked;
	}

	public void setPrevSuccess(int prevSuccess)
	{
		this.prevSuccess = prevSuccess&0xff;
	}

	public int getInitEsc()
	{
		return initEsc;
	}

	public void setInitEsc(int initEsc)
	{
		this.initEsc = initEsc;
	}

	public void setRunLength(int runLength)
	{
		this.runLength = runLength;
	}