java-org.hwo/src/org/hwo/compressor/LZW.java

package org.hwo.compressor;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.LinkedList;

import org.hwo.Reverse;
import org.hwo.Unsigned;
import org.hwo.buffer.BitStream;

public class LZW {
	
	static short CLEARCODE = (short)256;
	static short ENDOFINFORMATION = (short)257;
	
	ArrayList<Byte[]> stringTable;
	ArrayList<Byte>	omega;
	
	LinkedList<Byte>	uncompressed;
	BitStream			compressed;
	
	private boolean				byteOrder;
	
	public LZW()
	{
		stringTable = new ArrayList<Byte[]>();
		omega = new ArrayList<Byte>();
		uncompressed = new LinkedList<Byte>();
		compressed = new BitStream();
	}
	
	private void initializeStringTable()
	{
		stringTable.clear();
		for (short n=0;n<256;n++)
			stringTable.add(new Byte[]{ (byte)n });
		
		stringTable.add(new Byte[0]);
		stringTable.add(new Byte[0]);
		
	}
	
	private byte getSymbolLength()
	{
		if (stringTable.size() < 511)
			return 9;
		if (stringTable.size() < 1023)
			return 10;
		if (stringTable.size() < 2047)
			return 11;
		return 12;		
	}
	
	public void compress()
	{
		
	}
	
	public void decompress()
	{
		short symbol,
			lastsymbol = 0;
		
		uncompressed.clear();
		initializeStringTable();
		
		try
		{
		
		while ( (symbol = compressed.read(getSymbolLength())) != ENDOFINFORMATION)
		{
			if (symbol == CLEARCODE)
			{
				initializeStringTable();
				symbol = compressed.read(getSymbolLength());
				if (symbol == ENDOFINFORMATION)
					break;
				
				uncompressed.addAll(Arrays.asList(stringTable.get(symbol)));
				lastsymbol = symbol;
			} else
			{
				if (symbol < stringTable.size())
				{
					Byte[] codeString = stringTable.get(symbol);
					uncompressed.addAll(Arrays.asList(codeString));
					
					Byte[] b = stringTable.get(lastsymbol);
					Byte[] nb = Arrays.copyOf(b, b.length + 1 );
					nb[ b.length ] = codeString[0];
					stringTable.add(nb);
				} else
				{
					Byte[] b = stringTable.get(lastsymbol);
					Byte[] nb = Arrays.copyOf(b, b.length + 1 );
					nb[ b.length ] = b[0];
					stringTable.add(nb);
					uncompressed.addAll(Arrays.asList(nb));
				}
				lastsymbol = symbol;
			}
		}
		
		
		} catch (Exception e)
		{
			e.printStackTrace();
		}
	}
	
	
	
	public Byte[] getBoxedUncompressedData()
	{
		return uncompressed.toArray(new Byte[0]);
	}
	public byte[] getUncompressedData()
	{
		Byte[] boxed = getBoxedUncompressedData();
		byte[] unboxed = new byte[ boxed.length ];
		
		for (int i=0;i<boxed.length;i++)
			unboxed[i] = boxed[i];
			
		return unboxed;
	}
	
	
	public void setUncompressedData(Byte[] data)
	{
		uncompressed.clear();
		uncompressed.addAll(Arrays.asList(data));
	}
	
	public Byte[] getBoxedCompressedData()
	{
		byte[] unboxed = compressed.getBuffer();
		Byte[] boxed = new Byte[ unboxed.length ];
		for (int i=0;i<unboxed.length;i++)
			boxed[i] = unboxed[i];
		return boxed;
	}
	public byte[] getCompressedData()
	{
		return compressed.getBuffer();
	}

	public void setCompressedData(Byte[] data)
	{
		compressed = new BitStream(data);
	}
	public void setCompressedData(byte[] data)
	{
		compressed = new BitStream(data);
	}

	public boolean isByteOrder() {
		return byteOrder;
	}

	public void setByteOrder(boolean byteOrder) {
		this.byteOrder = byteOrder;
		this.compressed.setByteOrder(byteOrder);
	}
	
	
}