Struct Matrix

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pub struct Matrix { /* private fields */ }

Expand description

A row-major rows x cols matrix over GF(2^8).

For an encode matrix, rows = k + p (sources + parity, ISA-L’s m) and cols = k; the top k x k block is the identity, so source shards pass through unchanged and the bottom p rows generate parity.

Implementations§

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impl Matrix

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pub fn reed_solomon(k: usize, p: usize) -> Result<Matrix, MatrixError>

Vandermonde-style encode matrix for k sources and p parity rows — ISA-L’s gf_gen_rs_matrix, refusing the configurations ISA-L’s own documentation marks unsafe (where some decode submatrices are singular). Outside the safe region use Matrix::cauchy.

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pub fn cauchy(k: usize, p: usize) -> Result<Matrix, MatrixError>

Cauchy encode matrix for k sources and p parity rows — ISA-L’s gf_gen_cauchy1_matrix. Every square submatrix is invertible, so any (k, p) within the field limit is a valid configuration; this is the recommended general-purpose construction.

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pub fn from_bytes( rows: usize, cols: usize, data: Vec<u8>, ) -> Result<Matrix, MatrixError>

Build a matrix from raw row-major bytes. data.len() must equal rows * cols, and both dimensions must be in 1..=256 (the GF(2^8) shard-index limit; the field-based constructors are stricter because their constructions need ≤ 255 distinct nonzero elements).

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pub fn rows(&self) -> usize

Number of rows (k + p for an encode matrix — ISA-L’s m).

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pub fn cols(&self) -> usize

Number of columns (k, the source count, for an encode matrix).

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pub fn get(&self, row: usize, col: usize) -> Option<u8>

The coefficient at (row, col), or None out of bounds.

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pub fn as_bytes(&self) -> &[u8] ⓘ

The raw row-major coefficient bytes.

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pub fn parity_bytes(&self) -> &[u8] ⓘ

The bottom p rows — the parity-generating block, in exactly the layout tables::init_tables expects.

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pub fn select_rows(&self, indices: &[usize]) -> Result<Matrix, MatrixError>

Select indices.len() rows (in order) into a new matrix — the step that builds a decode matrix from the surviving shards’ rows. Indices must be in range; duplicates are allowed here and will simply produce a singular matrix at inversion.

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pub fn invert(&self) -> Result<Matrix, MatrixError>

Invert a square matrix — ISA-L’s gf_invert_matrix (Gauss-Jordan with row-swap pivoting), except non-destructive and with singularity as a typed error. Non-square input is a dimension error.

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