/**
* Compute the first few words of the XOR aggregate between two iterators.
*
* @param container where to write
* @param desiredrlwcount number of words to be written (max)
* @param rlwi first iterator to aggregate
* @param rlwj second iterator to aggregate
*/
public static void xorToContainer(
final BitmapStorage32 container,
int desiredrlwcount,
final IteratingRLW32 rlwi,
IteratingRLW32 rlwj) {
while ((rlwi.size() > 0) && (rlwj.size() > 0) && (desiredrlwcount-- > 0)) {
while ((rlwi.getRunningLength() > 0) || (rlwj.getRunningLength() > 0)) {
final boolean i_is_prey = rlwi.getRunningLength() < rlwj.getRunningLength();
final IteratingRLW32 prey = i_is_prey ? rlwi : rlwj;
final IteratingRLW32 predator = i_is_prey ? rlwj : rlwi;
if (!predator.getRunningBit()) {
int index = discharge(container, prey, predator.getRunningLength());
container.addStreamOfEmptyWords(false, predator.getRunningLength() - index);
predator.discardFirstWords(predator.getRunningLength());
} else {
int index = dischargeNegated(container, prey, predator.getRunningLength());
container.addStreamOfEmptyWords(true, predator.getRunningLength() - index);
predator.discardFirstWords(predator.getRunningLength());
}
}
final int nbre_literal =
Math.min(rlwi.getNumberOfLiteralWords(), rlwj.getNumberOfLiteralWords());
if (nbre_literal > 0) {
desiredrlwcount -= nbre_literal;
for (int k = 0; k < nbre_literal; ++k)
container.addWord(rlwi.getLiteralWordAt(k) ^ rlwj.getLiteralWordAt(k));
rlwi.discardFirstWords(nbre_literal);
rlwj.discardFirstWords(nbre_literal);
}
}
}
/**
* Write out up to max words, returns how many were written
*
* @param container target for writes
* @param i source of data
* @param max maximal number of writes
* @return how many written
*/
protected static int discharge(final BitmapStorage32 container, IteratingRLW32 i, int max) {
int counter = 0;
while (i.size() > 0 && counter < max) {
int l1 = i.getRunningLength();
if (l1 > 0) {
if (l1 + counter > max) l1 = max - counter;
container.addStreamOfEmptyWords(i.getRunningBit(), l1);
counter += l1;
}
int l = i.getNumberOfLiteralWords();
if (l + counter > max) l = max - counter;
for (int k = 0; k < l; ++k) {
container.addWord(i.getLiteralWordAt(k));
}
counter += l;
i.discardFirstWords(l + l1);
}
return counter;
}
/**
* Write out the content of the iterator, but as if it were all zeros.
*
* @param container where we write
* @param i the iterator
*/
protected static void dischargeAsEmpty(final BitmapStorage32 container, final IteratingRLW32 i) {
while (i.size() > 0) {
container.addStreamOfEmptyWords(false, i.size());
i.next();
}
}
