I was reading the Redis source code, specifically the siphash.c file, as well
as this Ruby
version
and I noticed that they both seemed to do achieve the same thing but
differently. Redis used n & 7 while the Ruby version used n % 8
And it turns out that when you're trying to get the power of two modulo of a
number, you can instead do n & (m-1) where m is the power of two.
So it works with 2, 4, 8, 16, 32, 64, ... you get it
More info on StackOverflow: https://stackoverflow.com/questions/6670715/mod-of-power-2-on-bitwise-operators