Struct Xorshift64 

#[repr(transparent)]
pub struct Xorshift64(pub u64);

A pseudo-random number generator (PRNG) that uses a [Xorshift algorithm]¹ to generate 64 bits of randomness at a time, represented by a u64.

Xorshift is a type of linear-feedback shift register that uses only three right-shifts and three xor operations per generated number, making it very efficient. Xorshift64 has a period of 2⁶⁴-1: it yields every number in the interval [1, 2⁶⁴) exactly once before repeating.

---

1. Marsaglia, G. (2003). Xorshift RNGs. Journal of Statistical Software, 8(14), 1–6. https://doi.org/10.18637/jss.v008.i14 ↩

Tuple Fields

0: u64

Implementations

impl Xorshift64

pub const DEFAULT_SEED: u64 = 378_682_147_834_061u64

A random 64-bit prime, used to initialize the generator returned by Xorshift64::default().

pub fn from_seed(seed: u64) -> Self

Returns a new Xorshift64 seeded by the given number.

Two Xorshift64 instances generate the same sequence of pseudo-random numbers if and only if they were created with the same seed. (Technically, every Xorshift64 instance yields values from the same sequence; the seed determines the starting point in the sequence).

Examples

use retrofire_core::math::rand::Xorshift64;

let mut g = Xorshift64::from_seed(123);
assert_eq!(g.next_bits(), 133101616827);
assert_eq!(g.next_bits(), 12690785413091508870);
assert_eq!(g.next_bits(), 7516749944291143043);

Panics

If seed equals 0.

pub fn from_time() -> Self

Returns a new Xorshift64 seeded by the current system time.

Note that depending on the precision of the system clock, two or more calls to this function in quick succession may return instances seeded by the same number.

Examples

use std::thread;
use retrofire_core::math::rand::Xorshift64;

let mut g = Xorshift64::from_time();
thread::sleep_ms(1); // Just to be sure
let mut h = Xorshift64::from_time();
assert_ne!(g.next_bits(), h.next_bits());

pub fn next_bits(&mut self) -> u64

Returns 64 bits of pseudo-randomness.

Successive calls to this function (with the same self) will yield every value in the interval [1, 2⁶⁴) exactly once before starting to repeat the sequence.

Trait Implementations

impl Clone for Xorshift64

fn clone(&self) -> Xorshift64

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Xorshift64

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for Xorshift64

fn default() -> Self

Returns a Xorshift64 seeded with DEFAULT_SEED.

Examples

use retrofire_core::math::rand::Xorshift64;

let mut g = Xorshift64::default();
assert_eq!(g.next_bits(), 11039719294064252060);

impl Copy for Xorshift64