module rand // Ported from http://xoshiro.di.unimi.it/splitmix64.c struct Splitmix64 { mut: state u64 } /** * new_splitmix64 - a Splitmix64 PRNG generator * @param seed the initial seed of the PRNG. * @return a new Splitmix64 PRNG instance */ pub fn new_splitmix64(seed u64) Splitmix64 { return Splitmix64{ seed } } /** * Splitmix64.next - update the PRNG state and get back the next random number * @return the generated pseudo random number */ [inline] pub fn (rng mut Splitmix64) next() u64 { rng.state += (0x9e3779b97f4a7c15) mut z := rng.state z = (z ^ ((z >> u64(30)))) * (0xbf58476d1ce4e5b9) z = (z ^ ((z >> u64(27)))) * (0x94d049bb133111eb) return z ^ (z >> (31)) } /** * Splitmix64.bounded_next - Get the next random number < bound * @param bound - the returned random number will be < bound * @return the generated pseudo random number */ [inline] pub fn (rng mut Splitmix64) bounded_next(bound u64) u64 { threshold := -bound % bound for { r := rng.next() if r >= threshold { return r % bound } } return u64(0) }