给定unsigned int,获取set位的"索引"的最快方法是什么？

unsigned int get_nth_set_bit_index(unsigned int x, int n) {
    unsigned int mask = 1;
    int count = 0;
    for (int i = 0; i < 32; i++) {
        if ((x & mask) != 0) {
            count++;
            if (count == n) {
                return i;
            }
        }
        mask <<= 1;
    }
    return -1; // 如果n大于set位的数量，返回-1
}