Struct Xabc

pub struct Xabc { /* private fields */ }

Available on crate feature rand only.

X ABC Algorithm Random Number Generator for 8-bit Devices.

It has a 32-bit state and generates 8-bit numbers.

This is a small PRNG, experimentally verified to have at least a 50 million byte period by generating 50 million bytes and observing that there were no overapping sequences and repeats.

This generator passes serial correlation, entropy, Monte Carlo Pi value, arithmetic mean, and many other statistical tests. This generator may have a period of up to 2^32, but this has not been verified.

By XORing 3 bytes into the a, b, and c registers, you can add in entropy from an external source easily.

This generator is free to use, but is not suitable for cryptography due to its short period (by cryptographic standards) and simple construction. No attempt was made to make this generator suitable for cryptographic use.

Due to the use of a constant counter, the generator should be resistant to latching up. A significant performance gain is had in that the x variable is only ever incremented.

Only 4 bytes of ram are needed for the internal state, and generating a byte requires 3 XORs, 2 ADDs, one bit shift right, and one increment. Difficult or slow operations like multiply, etc were avoided for maximum speed on ultra low power devices.

It has a period of 487,780,609 from a zeroed state.

License

This algorithm was originally openly published in December 2011 by user EternityForest in Electro-Tech-Online.com.

Implementations

impl Xabc

pub const fn new(seeds: [u8; 3]) -> Self

Returns a seeded Xabc generator from the given 3 × 8-bit seeds.

pub fn reseed(&mut self, seeds: [u8; 3])

Reseeds the generator from the given 3 × 8-bit seeds.

pub const fn current_u8(&self) -> u8

Returns the current random u8.

pub fn next_u8(&mut self) -> u8

Returns the next random u8.

pub const fn next_state(&self) -> Self

Returns a copy of the next new random state.

pub const fn own_next_u8(self) -> Own<Self, u8>

Returns both the next random state and the u8 value.

impl Xabc

Extra constructors

pub const fn new3_u8(seeds: [u8; 3]) -> Self

Returns a seeded Xabc generator from the given 3 × 8-bit seeds.

This is an alias of new.

Trait Implementations

impl Clone for Xabc

fn clone(&self) -> Xabc

Returns a copy of the value.

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

Performs copy-assignment from source.

impl ConstDefault for Xabc

const DEFAULT: Self

Returns the compile-time “default value” for a type.

impl Debug for Xabc

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

Formats the value using the given formatter.

impl Default for Xabc

fn default() -> Self

Returns the “default value” for a type.

impl PartialEq for Xabc

fn eq(&self, other: &Xabc) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl RngCore for Xabc

Available on crate feature dep_rand_core only.

fn next_u32(&mut self) -> u32

Returns the next 4 × random u8 combined as a single u32.

fn next_u64(&mut self) -> u64

Returns the next 8 × random u8 combined as a single u64.

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

Fill dest with random data.

fn try_fill_bytes(&mut self, dest: &mut [u8]) -> Result<(), Error>

Fill dest entirely with random data.

impl SeedableRng for Xabc

Available on crate feature dep_rand_core only.

type Seed = [u8; 3]

Seed type, which is restricted to types mutably-dereferenceable as u8 arrays (we recommend [u8; N] for some N).

fn from_seed(seed: Self::Seed) -> Self

Create a new PRNG using the given seed.

fn seed_from_u64(state: u64) -> Self

Create a new PRNG using a u64 seed.

fn from_rng<R>(rng: R) -> Result<Self, Error>

where R: RngCore,

Create a new PRNG seeded from another Rng.

fn from_entropy() -> Self

Creates a new instance of the RNG seeded via getrandom.

impl Copy for Xabc

impl Eq for Xabc

impl StructuralPartialEq for Xabc