mask |= (mask >> 16);
_mask = mask;
_filter = new long[mask + 1];
IntIterator iter = set.iterator();
while (iter.hasNext()) {
int h = iter.nextInt() * MIXER;
long bits = _filter[h & _mask];
bits |= ((1L << (h >>> 26)));
bits |= ((1L << ((h >> 20) & 0x3F)));
_filter[h & _mask] = bits;