1 popcnt 0 -> 0 cc=0 2 popcnt 1 -> 1 cc=1 3 popcnt 8000000000000000 -> 100000000000000 cc=1 4 popcnt ffffffffffffffff -> 808080808080808 cc=1 5 popcnt ff427e3800556bcd -> 802060300040505 cc=1 6