Struct PartialRoundConstants 

pub struct PartialRoundConstants<F, const WIDTH: usize> {
    pub first_round_constants: [F; WIDTH],
    pub m_i: [[F; WIDTH]; WIDTH],
    pub sparse_first_row: Vec<[F; WIDTH]>,
    pub v: Vec<[F; WIDTH]>,
    pub round_constants: Vec<F>,
    pub textbook_scalar_constants: Vec<F>,
    pub textbook_residual: [F; WIDTH],
}

Pre-computed constants for the RP partial (internal) rounds.

These are produced by the sparse matrix decomposition in crate::utils.

Fields

first_round_constants: [F; WIDTH]

Full WIDTH-vector of optimized round constants, added once before the transition matrix m_i.

This vector absorbs the original round constants from all RP partial rounds via backward substitution through M^{-1}.

m_i: [[F; WIDTH]; WIDTH]

Dense transition matrix m_i, applied once before the partial round loop.

This is the accumulated product of sparse matrix factors from the sparse matrix decomposition, transposed to match the HorizenLabs convention.

sparse_first_row: Vec<[F; WIDTH]>

Per-round full first row of the sparse matrix, pre-assembled for branch-free dot product computation.

sparse_first_row[r] = [mds_0_0, ŵ_r[0], ŵ_r[1], ..., ŵ_r[WIDTH-2]]

where mds_0_0 is the top-left entry of the original MDS matrix (same for all rounds) and ŵ_r is the per-round first-row vector from the sparse factorization.

Length = RP. Stored in forward application order.

v: Vec<[F; WIDTH]>

Per-round first-column vectors for the sparse matrix multiply (excluding the [0,0] entry).

v[r] has WIDTH elements: [v_r[0], v_r[1], ..., v_r[WIDTH-2], 0]. Only the first WIDTH-1 entries are meaningful; the last is padding.

Length = RP. Stored in forward application order.

round_constants: Vec<F>

Optimized scalar round constants for partial rounds 0 through RP-2.

The last partial round has no additive constant (it was absorbed by the backward substitution). Length = RP - 1.

textbook_scalar_constants: Vec<F>

Scalar constants for the textbook partial round path.

Length = RP. Each entry is the optimized scalar to add to state[0] before the S-box, computed via forward constant substitution.

textbook_residual: [F; WIDTH]

Residual accumulator for the textbook path.

Added to the state after all partial rounds complete. Accounts for the folded-forward state[1..WIDTH] constants.

Trait Implementations

impl<F: Clone, const WIDTH: usize> Clone for PartialRoundConstants<F, WIDTH>

fn clone(&self) -> PartialRoundConstants<F, WIDTH>

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl<F: Debug, const WIDTH: usize> Debug for PartialRoundConstants<F, WIDTH>

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

Formats the value using the given formatter.