Struct ExternalLayerConstants 

pub struct ExternalLayerConstants<T, const WIDTH: usize> { /* private fields */ }

A struct which stores round-specific constants for both initial and terminal external layers.

Implementations

impl<T, const WIDTH: usize> ExternalLayerConstants<T, WIDTH>

pub const fn new(initial: Vec<[T; WIDTH]>, terminal: Vec<[T; WIDTH]>) -> Self

Create a new instance of external layer constants.

Panics

Panics if initial.len() != terminal.len() since the Poseidon2 spec requires the same number of initial and terminal rounds to maintain symmetry.

pub fn new_from_rng<R: Rng>(external_round_number: usize, rng: &mut R) -> Self

where StandardUniform: Distribution<[T; WIDTH]>,

Randomly generate a new set of external constants using a provided RNG.

Arguments

• external_round_number: Total number of external rounds (must be even).
• rng: A random number generator that supports uniform sampling.

The constants are split equally between the initial and terminal rounds.

Panics

Panics if external_round_number is not even.

pub fn new_from_saved_array<U, const N: usize>( [initial, terminal]: [[[U; WIDTH]; N]; 2], conversion_fn: fn([U; WIDTH]) -> [T; WIDTH], ) -> Self

where T: Clone,

Construct constants from statically stored arrays, using a conversion function.

This is useful when deserializing precomputed constants or embedding them directly in the codebase (e.g., from [[[u32; WIDTH]; N]; 2] arrays).

Arguments

• initial, terminal: Two fixed-size arrays of size N containing round constants.
• conversion_fn: A function to convert from the source type U to T.

pub const fn get_initial_constants(&self) -> &Vec<[T; WIDTH]>

Get a reference to the list of initial round constants.

These are used in the first half of the external rounds.

pub const fn get_terminal_constants(&self) -> &Vec<[T; WIDTH]>

Get a reference to the list of terminal round constants.

These are used in the second half (terminal rounds) of the external layer.

Trait Implementations

impl<T: Clone, const WIDTH: usize> Clone for ExternalLayerConstants<T, WIDTH>

fn clone(&self) -> ExternalLayerConstants<T, WIDTH>

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl<T: Debug, const WIDTH: usize> Debug for ExternalLayerConstants<T, WIDTH>

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

Formats the value using the given formatter.