private static byte[] get4bytes(long l)
	{
		// break down to bytes
		byte a[] = new byte[4];
		a[0] = (byte)((l & 0x00000000ff000000) >> 24);
		a[1] = (byte)((l & 0x0000000000ff0000) >> 16);
		a[2] = (byte)((l & 0x000000000000ff00) >> 8);
		a[3] = (byte)((l & 0x00000000000000ff) >> 0);
		// assemble back
		// ll != l.
		long ll = ((unsigned(a[0]) << 24)&0xff000000) | 
				  ((unsigned(a[1]) << 16)&0x00ff0000) | 
				  ((unsigned(a[2]) <<8)  &0x0000ff00) | 
				  (unsigned(a[3])        &0x000000ff);
		System.err.println("original " + l);
		System.err.println("new  " + ll);
		return a;
	}
	
	static byte unsigned(byte b)
	{
		if (b < 0)
		{
			b += 128;
		}
		return b;
	}