Struct PolyBasisNtt 

pub struct PolyBasisNtt { /* private fields */ }

LchNtt over BinaryField128, with the data held in the polynomial basis throughout.

A tower-basis product converts both operands into the polynomial basis and the result back, sixteen dependent table lookups apiece, which is most of what a butterfly costs. Converting the whole matrix once on the way in and once on the way out pays 2 conversions per element instead of 3ℓ/2, and every twiddle multiply in between is a bare carryless multiply and a reduction. Additions are XOR in both bases, so they are unaffected.

Without a carryless-multiply instruction that product is a bit-serial loop and slower than the tower arithmetic it replaces, so on such a target the transform runs in the tower basis instead, using typed subfield multiplication when the twiddle permits it. The choice is a constant and only one arm survives compilation.

Trait Implementations

impl AdditiveNtt<BinaryField128> for PolyBasisNtt

fn shifted_ntt_batch( &self, mat: RowMajorMatrix<BinaryField128>, shift: BinaryField128, ) -> RowMajorMatrix<BinaryField128>

Evaluates each column on the coset shift + S_ℓ.

fn ntt_batch_padded( &self, mat: RowMajorMatrix<BinaryField128>, log_inv_rate: usize, ) -> RowMajorMatrix<BinaryField128>

Transforms a matrix whose coefficient prefix has been padded with zero rows.

fn shifted_lde_batch( &self, mat: RowMajorMatrix<BinaryField128>, added_bits: usize, shift: BinaryField128, ) -> RowMajorMatrix<BinaryField128>

lde_batch on the coset shift + S_{ℓ + added_bits}.

fn shifted_intt_batch( &self, mat: RowMajorMatrix<BinaryField128>, shift: BinaryField128, ) -> RowMajorMatrix<BinaryField128>

Inverse of shifted_ntt_batch.

fn ntt_batch(&self, mat: RowMajorMatrix<F>) -> RowMajorMatrix<F>

Evaluates each column on S_ℓ.

fn intt_batch(&self, mat: RowMajorMatrix<F>) -> RowMajorMatrix<F>

Inverse of ntt_batch.

fn lde_batch( &self, mat: RowMajorMatrix<F>, added_bits: usize, ) -> RowMajorMatrix<F>

Low-degree extension onto S_{ℓ + added_bits} ⊃ S_ℓ.

impl Clone for PolyBasisNtt

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for PolyBasisNtt

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

Formats the value using the given formatter.

impl Default for PolyBasisNtt

fn default() -> Self

Returns the “default value” for a type.