java-org.hwo/src/org/hwo/buffer/BitStream.java

package org.hwo.buffer;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

public class BitStream {

	private boolean byteOrder;
	
	private int pByte;
	private byte pBit;
	
	private List<Byte> buffer;
	
	public BitStream()
	{
		initialize();
		
		buffer = new ArrayList<Byte>();
	}
	
	public BitStream(byte[] source)
	{
		initialize();
		
		buffer = new ArrayList<Byte>();
		for (byte b:source)
			buffer.add(b);
	}
	
	public BitStream(Byte[] source)
	{
		initialize();
		
		buffer = new ArrayList<Byte>(Arrays.asList(source));
	}
	
	private void initialize()
	{
		pByte = 0;
		pBit = 0;
	}
	
	private short unsigned2short(byte by)
	{
		short s;
		
		if (by < 0)
		{
			s = (short)(128 | (by & 0x7f));
		} else
			s = by;

		return s;
	}
	
	public short read(byte bits)
	{
		short symbol = 0;
		byte position = 0;	// Bit-Position im symbol
		
		while (bits > 0)
		{
			symbol <<= 1;
			
			short s = (short)( unsigned2short(buffer.get(pByte)));
			
			if (byteOrder)
			{
				s >>= pBit;
				if ((s & 0x01) == 0x01)
					symbol |= 0x01;				
			} else
			{
				s <<= pBit;
				if ((s & 0x80) == 0x80)
					symbol |= 0x01;
			};
			
			pBit++;
			if (pBit == 8)
			{
				pBit = 0;
				pByte++;
			}
			bits--;
		}
		return symbol;
	}
	
	
	
	public byte[] getBuffer()
	{
		int len = buffer.size();
		byte[] out = new byte[ len ];
		for (int i=0;i<len;i++)
			out[i] = buffer.get(i);
		return out;
	}

	public boolean isByteOrder() {
		return byteOrder;
	}

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