find_bits.c

/* Find set bits by value. process_faster() is between 40% and 200% faster than process_naive(), depending on optimizations and environment. */
void process_naive(long long x)
{
    long long val = 1;
    while (x) {
        if (x & 1)
            record(val);
        x >>= 1;
        val <<= 1;
    }
}

void process_faster(long long x)
{
    while (x) {
        int val = x ^ (x & (x - 1));
        record(val);
        x &= ~val;
    }
}