/**
* Shifts in byte b and mods with poly
*
* <p>If we have passed overflowed our window, we pop a byte
*/
@Override
public synchronized void pushByte(byte b) {
Polynomial f = fingerprint;
f = f.shiftLeft(byteShift);
f = f.or(Polynomial.createFromLong(b & 0xFFL));
f = f.mod(poly);
fingerprint = f;
if (bytesPerWindow > 0) {
byteWindow.add(b);
if (byteWindow.isFull()) popByte();
}
}
/**
* Removes the contribution of the first byte in the byte queue from the fingerprint.
*
* <p>Note that the shift necessary to calculate it's contribution can be sizeable, and the mod
* calculation will be similarly slow. It is therefore done with the Polynomial to support
* arbitrary sizes.
*
* <p>Note that despite this massive shift, the fingerprint will still result in a k-bit number at
* the end of the calculation.
*/
public synchronized void popByte() {
byte b = byteWindow.poll();
Polynomial f = Polynomial.createFromLong(b & 0xFFL);
f = f.shiftLeft(windowShift);
f = f.mod(poly);
fingerprint = fingerprint.xor(f);
}