Struct SplitMix64 

pub struct SplitMix64 { /* private fields */ }

A splitmix64 generator (Steele, Lea & Flood 2014).

Carries its 64-bit state, advances by the golden gamma and runs the xorshift-multiply output function. Two bytes of state for a passing statistical battery is the reason this and not an LCG is the shared PRNG: tests that need deterministic “random” data seed it with a constant, never with the clock.

let mut rng = pith_digest::SplitMix64::new(0);
assert_eq!(rng.next_u64(), 0xe220_a839_7b1d_cdaf);
assert_eq!(rng.next_u64(), 0x6e78_9e6a_a1b9_65f4);

Implementations

impl SplitMix64

pub const fn new(seed: u64) -> Self

Creates a generator seeded with seed.

pub fn next_u64(&mut self) -> u64

Produces the next 64-bit output and advances the state.

pub fn fill_bytes(&mut self, out: &mut [u8])

Produces n pseudo-random bytes, filling out exactly.

Deterministic in out.len() and the seed alone, so a test can regenerate the same corpus on any machine.

Trait Implementations

impl Clone for SplitMix64

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.