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TIPE/Code/ldpc/src/construction/random.rs
2026-02-12 12:32:46 +01:00

54 lines
1.6 KiB
Rust

use crate::matrix::MatrixGF2;
use rand::RngExt;
// H doit respecter les contraine des poids w_c et w_r
pub fn generate_random_h(rows: usize, cols: usize, wc: usize, wr: usize) -> MatrixGF2 {
assert_eq!(rows * wr, cols * wc, "Erreur");
loop {
let mut data = vec![0; rows * cols];
let mut row_w = vec![0; rows];
let mut rng = rand::rng();
let mut success = true;
for c in 0..cols {
let mut ones_placed = 0;
let mut avail_rows: Vec<usize> = (0..rows).filter(|&r| row_w[r] < wr).collect();
if avail_rows.len() < wc {
// Les problèmes...
success = false;
break;
}
while ones_placed < wc {
let id = rng.random_range(0..avail_rows.len());
let r = avail_rows.remove(id);
data[r * cols + c] = 1;
row_w[r] += 1;
ones_placed += 1;
}
}
if success {
return MatrixGF2::new(rows, cols, data);
}
}
}
pub fn generate_random_h_for_k(k: usize, wc: usize, wr: usize) -> MatrixGF2 {
assert!(wr > wc, "wr < wc ...");
assert!((k * wr) % (wr - wc) == 0, "Colonnes non entieres");
let n = (k * wr) / (wr - wc);
let m = n - k;
// On garde que les matrice de rang m
loop {
let h_matrix = generate_random_h(m, n, wc, wr);
let mut h_test = h_matrix.clone();
let (rank, _) = h_test.gauss_jordan_swap_cols();
if rank == m {
return h_matrix;
}
}
}