while (i < to) {
    ui64 row = rows[rowIndex];
    ui64 bitchange = i++;
    bitchange ^= i;
    rowIndex = 63-__builtin_clzll(bitchange);

    ui64 cardinality = 0;
    for (int j=0; j<8; j++) {
        curr[j] ^= row[j];
        cardinality += __builtin_popcountll(curr[j]);
    }
    popcountpolynomial[cardinality]++;
}