public class ParityChecksum implements Checksum { long checksum = 0;
public void update(int b) { int numOneBits = 0; for (int i = 1; i < 256; i *= 2) { if ((b & i) != 0)
numOneBits++;
}
checksum = (checksum + numOneBits) % 2;
}
public void update(byte data[], int offset, int length) { for (int i = offset; i < offset + length; i++) { this.update(data[i]);
}
}