ldpc rust

Code/ldpc/src/encoder/dense.rs

@@ -0,0 +1,59 @@
+use crate::code::{self, LdpcCode};
+use crate::matrix::MatrixGF2;
+
+pub struct DenseEncoder {
+    pub g_matrix: MatrixGF2,
+    pub h_reduced: MatrixGF2, // A enlever c'est juste pour l'affichage...
+    pub k: usize,
+    pub n: usize,
+    pub col_swaps: Vec<(usize, usize)>,
+}
+
+impl DenseEncoder {
+    pub fn new(code: &LdpcCode) -> Self {
+        let mut h_reduced = code.h_matrix.clone();
+        let (rank, col_swaps) = h_reduced.gauss_jordan_swap_cols();
+
+        let n = h_reduced.cols;
+        let k = n - rank;
+
+        let mut g_data = vec![0; k * n];
+
+        for r in 0..k {
+            for c in 0..rank {
+                g_data[r * n + c] = h_reduced.get(c, rank + r);
+            }
+        }
+        for i in 0..k {
+            g_data[i * n + (rank + i)] = 1;
+        }
+        Self {
+            g_matrix: MatrixGF2::new(k, n, g_data),
+            h_reduced,
+            k,
+            n,
+            col_swaps,
+        }
+    }
+
+    pub fn encode(&self, message: &[u8]) -> Vec<u8> {
+        assert_eq!(message.len(), self.k, "Taille du message non valide");
+        let mut codeword = vec![0; self.n];
+
+        // s = u * G
+        for c in 0..self.n {
+            let mut sum = 0;
+            for r in 0..self.k {
+                sum ^= message[r] & self.g_matrix.get(r, c);
+            }
+            codeword[c] = sum;
+        }
+
+        // Reverse les changement de colonnes
+        for &(c1, c2) in self.col_swaps.iter().rev() {
+            codeword.swap(c1, c2);
+        }
+
+        codeword
+    }
+}