COUNTER_BITS_TOTAL
COUNTER_WINDOW_SIZE = COUNTER_BITS_TOTAL - COUNTER_REDUNDANT_BITS
unsigned long backtrack[COUNTER_BITS_TOTAL / BITS_PER_LONG];
COUNTER_BITS_TOTAL / BITS_PER_LONG);
((COUNTER_BITS_TOTAL / BITS_PER_LONG) - 1)] = 0;
index &= (COUNTER_BITS_TOTAL / BITS_PER_LONG) - 1;