fec: LDPC: Adding class for LDPC parity check matrix.

This code is from GSOC 2013; start of the port into gr-fec.

gr-fec/include/gnuradio/fec/ldpc_parity_check_matrix.h

@@ -0,0 +1,126 @@
+/* -*- c++ -*- */
+/* 
+ * Copyright 2013-2014 Free Software Foundation, Inc.
+ * 
+ * This is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published 
+ * by the Free Software Foundation; either version 3, or (at your 
+ * option) any later version.
+ * 
+ * This software is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License
+ * along with this software; see the file COPYING.  If not, write to
+ * the Free Software Foundation, Inc., 51 Franklin Street,
+ * Boston, MA 02110-1301, USA.
+ */
+
+#ifndef INCLUDED_LDPC_PARITY_CHECK_MATRIX
+#define INCLUDED_LDPC_PARITY_CHECK_MATRIX
+
+#include <string>
+#include <cmath>
+#include <gsl/gsl_matrix.h>
+#include <gsl/gsl_randist.h>
+#include <gsl/gsl_permutation.h>
+#include <gsl/gsl_linalg.h>
+#include <gsl/gsl_blas.h>
+using namespace std;
+
+class LDPC_parity_check_matrix
+{
+    // Codeword length n (also the number of columns in the H matrix)
+    unsigned int d_n;
+    // Information word length k
+    unsigned int d_k;
+    // Rank of the parity check matrix
+    unsigned int d_rank;
+    // Number of rows in the parity check matrix
+    unsigned int d_num_rows;
+    // Gap (when matrix is in TABECD form)
+    unsigned int d_gap;
+    // GSL matrix structure for the parity check matrix
+    gsl_matrix *d_H_ptr;
+
+
+public:
+    /* Overloading the constructor because the parity matrix may come
+       from one of three places and be in a few forms:
+       1. Be read in from a given filename (must be alist format)
+         a) encoding-ready. (Gap g must be provided)
+            Set flag = 1. This is the default flag/case.
+         b) full rank but not encoding ready
+            Set flag = 2. 
+         c) regular LDPC matrix, not (necessarily) full rank
+            Set flag = 3.
+         d) unknown state, so try (c)
+            Set flag = 4.
+       2. Be already existing in a GSL matrix object
+         - User must call functions as needed to get matrix into
+           encoding-ready state
+       3. Be generated by this class if the properties are specified
+    */
+
+    // Constructor if filename is given, case 1
+    LDPC_parity_check_matrix(string *,
+                             int flag = 1,
+                             unsigned int gap = 0);
+
+    // Constructor if a parity check matrix is given, case 2
+    LDPC_parity_check_matrix(gsl_matrix *);
+
+    // Constructor if n,p,q values are given, case 3
+    LDPC_parity_check_matrix(unsigned int n, 
+                             unsigned int p, 
+                             unsigned int q);
+
+    // Default constructor, should not be used
+    LDPC_parity_check_matrix();
+
+    // Get the codeword length n
+    unsigned int get_n();
+    // Get the information word length k
+    unsigned int get_k();
+    // Get the rank of the parity check matrix
+    unsigned int get_rank();
+
+    // These are the submatrices found during preprocessing which are
+    // used for encoding. TODO should these be private?
+    gsl_matrix *d_T_inverse;
+    gsl_matrix *d_phi_inverse;
+    gsl_matrix *d_E;
+    gsl_matrix *d_A;
+    gsl_matrix *d_B;
+    gsl_matrix *d_D;
+
+    // Write the matrix out to a file in alist format
+    void write_matrix_to_file(string *);
+    // Read the matrix from a file in alist format
+    void read_matrix_from_file(string *);
+    // Reduce a H matrix which is not full rank to be full rank
+    void reduce_H_to_full_rank_matrix();
+    // Transform full rank parity check H matrix to TABECD form
+    void full_rank_to_TABECD_form(bool extra_shuffle = false);
+    // Preprocess TABECD form matrix to get parameters for encoding
+    // Should only do this one time because it takes a while...
+    void preprocess_for_encoding();
+    // Set the submatrix variables needed for encoding
+    void set_parameters_for_encoding();
+    // Subtract matrices using mod2 operation
+    gsl_matrix *subtract_matrices_mod2(gsl_matrix *, gsl_matrix *);
+    // Perform matrix multiplication using mod 2 operations
+    gsl_matrix *matrix_mult_mod2(gsl_matrix *, gsl_matrix *);
+    // Find the inverse of a square matrix using modulo 2 operations
+    gsl_matrix *calc_inverse_mod2(gsl_matrix *);
+
+    // Destructor
+    ~LDPC_parity_check_matrix();
+
+};
+
+
+
+#endif /* INCLUDED_LDPC_HELPER_CLASSES_H */