Struct SeededRng 

pub struct SeededRng { /* private fields */ }

Seeded RNG for reproducible randomness.

Uses a simple xorshift64 algorithm for fast, reproducible random numbers. This is suitable for testing but not for cryptographic purposes.

Security Warning

SeededRng is deterministic and is not suitable for secrets, tokens, authentication nonces, key material, or any other security-sensitive use. Use a SecureRng implementation such as ChaCha20Rng::from_os_entropy() for those cases.

Algorithm

Xorshift64 with shifts (13, 7, 17) as described by Marsaglia (2003). Period is 2^64 - 1.

Example

use telltale_types::effects::{Rng, SeededRng};

let mut rng = SeededRng::new(12345);
let a = rng.next_u64();
let b = rng.next_u64();
assert_ne!(a, b);

// Same seed produces same sequence
let mut rng2 = SeededRng::new(12345);
assert_eq!(rng2.next_u64(), a);

Implementations

impl SeededRng

pub fn new(seed: u64) -> SeededRng

Create a new seeded RNG with an explicit seed.

For deterministic simulation, always use explicit seeds. A seed of 0 is replaced with 1 (xorshift requires non-zero state).

pub fn state(&self) -> u64

Get the current state (can be used to save/restore).

pub fn restore(&mut self, state: u64)

Restore from a previous state.

Trait Implementations

impl Clone for SeededRng

fn clone(&self) -> SeededRng

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for SeededRng

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

Formats the value using the given formatter.

impl Rng for SeededRng

fn next_u64(&mut self) -> u64

Generate a random u64.

fn fork(&mut self) -> SeededRng

Fork into an independent RNG stream.

fn next_u32(&mut self) -> u32

Generate a random u32.

fn next_bool(&mut self) -> bool

Generate a random boolean.

fn next_fixed(&mut self) -> FixedQ32

Generate a random FixedQ32 value in [0, 1).

fn next_u64_bounded(&mut self, bound: u64) -> u64

Generate a random u64 in the range [0, bound).

fn choose<'a, T>(&mut self, slice: &'a [T]) -> Option<&'a T>

Choose a random element from a slice.

fn duration_between(&mut self, min: Duration, max: Duration) -> Duration

Generate a random duration between min and max.

impl DeterministicRng for SeededRng