Most efficient way to calculate hamming distance in ruby?

Question

In ruby, what is the most efficient way to calculate the bit difference between two unsigned integers (e.g. the hamming distance)?

Eg, I have integer a = 2323409845

Answer 1

If one intends to follow c-based path, it is a good idea to add the compiler flag -msse4.2 to your makefile. This allows the compiler to generate hardware based popcnt instructions instead of using a table to generate the popcount. On my system this was approximately 2.5x faster.