/*
 * 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:
 * "&":  "&#038;" or "&amp;"
 * "<":  "&#060;" or "&lt;"
 * ">":  "&#062;" or "&gt;"
 * "@":  "&#064;" 
 */
package com.innosystec.unrar.unpack.ppm;

/**
 * DOCUMENT ME
 * 
 * @author $LastChangedBy$
 * @version $LastChangedRevision$
 */
public class SEE2Context
{
	public static final int size = 4;
	// ushort Summ;
	private int summ;
	// byte Shift;
	private int shift;
	// byte Count;
	private int count;

	public void init(int initVal)
	{
		shift = (ModelPPM.PERIOD_BITS - 4) & 0xff;
		summ = (initVal << shift) & 0xffff;
		count = 4;
	}

	public int getMean()
	{
		int retVal = summ >>> shift;
		summ -= retVal;
		return retVal + ((retVal == 0) ? 1 : 0);
	}

	public void update()
	{
		if(shift < ModelPPM.PERIOD_BITS && --count == 0)
		{
			summ += summ;
			count = (3 << shift++);
		}
		summ &= 0xffff;
		count &= 0xff;
		shift &= 0xff;
	}

	public int getCount()
	{
		return count;
	}

	public void setCount(int count)
	{
		this.count = count & 0xff;
	}

	public int getShift()
	{
		return shift;
	}

	public void setShift(int shift)
	{
		this.shift = shift & 0xff;
	}

	public int getSumm()
	{
		return summ;
	}

	public void setSumm(int summ)
	{
		this.summ = summ & 0xffff;
	}

	public void incSumm(int dSumm)
	{
		setSumm(getSumm() + dSumm);
	}

	public String toString()
	{
		StringBuffer buffer = new StringBuffer();
		buffer.append("SEE2Context[");
		buffer.append("\n  size=");
		buffer.append(size);
		buffer.append("\n  summ=");
		buffer.append(summ);
		buffer.append("\n  shift=");
		buffer.append(shift);
		buffer.append("\n  count=");
		buffer.append(count);
		buffer.append("\n]");
		return buffer.toString();
	}
}
