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+/* RCODE.C - Procedures to read parity check and generator matrices. */
+
+/* Copyright (c) 1995-2012 by Radford M. Neal.
+ *
+ * Permission is granted for anyone to copy, use, modify, and distribute
+ * these programs and accompanying documents for any purpose, provided
+ * this copyright notice is retained and prominently displayed, and note
+ * is made of any changes made to these programs.  These programs and
+ * documents are distributed without any warranty, express or implied.
+ * As the programs were written for research purposes only, they have not
+ * been tested to the degree that would be advisable in any important
+ * application.  All use of these programs is entirely at the user's own
+ * risk.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <math.h>
+
+#include "alloc.h"
+#include "intio.h"
+#include "open.h"
+#include "mod2sparse.h"
+#include "mod2dense.h"
+#include "mod2convert.h"
+#include "rcode.h"
+
+
+/* VARIABLES DECLARED IN RCODE.H.  These global variables are set to
+   representations of the parity check and generator matrices by read_pchk
+   and read_gen. */
+
+mod2sparse *H;		/* Parity check matrix */
+
+int M;			/* Number of rows in parity check matrix */
+int N;			/* Number of columns in parity check matrix */
+
+char type;		/* Type of generator matrix representation (s/d/m) */
+int *cols;		/* Ordering of columns in generator matrix */
+
+mod2sparse *L, *U;	/* Sparse LU decomposition, if type=='s' */
+int *rows;		/* Ordering of rows in generator matrix (type 's') */
+
+mod2dense *G;		/* Dense or mixed representation of generator matrix,
+			   if type=='d' or type=='m' */
+
+
+/* READ PARITY CHECK MATRIX.  Sets the H, M, and N global variables.  If an
+   error is encountered, a message is displayed on standard error, and the
+   program is terminated. */
+
+void read_pchk
+( char *pchk_file
+)
+{
+  FILE *f;
+
+  f = open_file_std(pchk_file,"rb");
+  if (f==NULL)
+  { fprintf(stderr,"Can't open parity check file: %s\n",pchk_file);
+    exit(1);
+  }
+
+  if (intio_read(f)!=('P'<<8)+0x80)
+  { fprintf(stderr,"File %s doesn't contain a parity check matrix\n",pchk_file);
+    exit(1);
+  }
+
+  H = mod2sparse_read(f);
+
+  if (H==0)
+  { fprintf(stderr,"Error reading parity check matrix from %s\n",pchk_file);
+    exit(1);
+  }
+
+  M = mod2sparse_rows(H);
+  N = mod2sparse_cols(H);
+
+  fclose(f);
+}
+
+
+/* READ GENERATOR MATRIX.  The parity check matrix must have already been 
+   read, unless the last argument is set to 1.  The generator matrix must be 
+   compatible with the parity check matrix, if it has been read.  If the 
+   second argument is 1, only the column ordering (the last N-M of which are 
+   the indexes of the message bits) is read, into the 'cols' global variable.  
+   Otherwise, everything is read, into the global variables appropriate
+   to the representation.  The 'type' global variable is set to a letter
+   indicating which represention is used. 
+
+   If an error is encountered, a message is displayed on standard error,
+   and the program is terminated. */
+
+void read_gen
+( char *gen_file,	/* Name of generator matrix file */
+  int cols_only,	/* Read only column ordering? */
+  int no_pchk_file	/* No parity check file used? */
+)
+{
+  int M2, N2;
+  FILE *f;
+  int i;
+
+  f = open_file_std(gen_file,"rb");
+  if (f==NULL)
+  { fprintf(stderr,"Can't open generator matrix file: %s\n",gen_file);
+    exit(1);
+  }
+
+  if (intio_read(f)!=('G'<<8)+0x80)
+  { fprintf(stderr,"File %s doesn't contain a generator matrix\n",gen_file);
+    exit(1);
+  }
+
+  if (fread (&type, 1, 1, f) != 1) goto error;
+
+  M2 = intio_read(f);
+  N2 = intio_read(f);
+
+  if (feof(f) || ferror(f)) goto error;
+
+  if (no_pchk_file)
+  { M = M2;
+    N = N2;
+  }
+  else 
+  { if (M2!=M || N2!=N)
+    { fprintf(stderr,
+              "Generator matrix and parity-check matrix are incompatible\n");
+      exit(1);
+    }
+  }
+
+  cols = chk_alloc (N, sizeof *cols);
+  rows = chk_alloc (M, sizeof *rows);
+
+  for (i = 0; i<N; i++)
+  { cols[i] = intio_read(f);
+    if (feof(f) || ferror(f)) goto error;
+  }
+
+  if (!cols_only)
+  {
+    switch (type)
+    {
+      case 's':
+      { 
+        for (i = 0; i<M; i++)
+        { rows[i] = intio_read(f);
+          if (feof(f) || ferror(f)) goto error;
+        }
+
+        if ((L = mod2sparse_read(f)) == 0) goto error;
+        if ((U = mod2sparse_read(f)) == 0) goto error;
+  
+        if (mod2sparse_rows(L)!=M || mod2sparse_cols(L)!=M) goto garbled;
+        if (mod2sparse_rows(U)!=M || mod2sparse_cols(U)<M) goto garbled;
+       
+        break;
+      }
+  
+      case 'd':
+      {
+        if ((G = mod2dense_read(f)) == 0) goto error;
+  
+        if (mod2dense_rows(G)!=M || mod2dense_cols(G)!=N-M) goto garbled;
+  
+        break;
+      }
+  
+      case 'm':
+      {
+        if ((G = mod2dense_read(f)) == 0) goto error;
+  
+        if (mod2dense_rows(G)!=M || mod2dense_cols(G)!=M) goto garbled;
+  
+        break;
+      }
+  
+      default: 
+      { fprintf(stderr,
+         "Unknown type of generator matrix in file %s\n",gen_file);
+        exit(1);
+      }
+    }
+  }
+  
+  fclose(f);
+
+  return;
+
+error:
+  fprintf(stderr,"Error reading generator matrix from file %s\n",gen_file);
+  exit(1);
+
+garbled:
+  fprintf(stderr,"Garbled generator matrix in file %s\n",gen_file);
+  exit(1);
+}
+
+// Fortran interface routines for WSJT-X
+void init_ldpc_ (char *pfile, char *gfile )
+{
+    read_pchk( pfile );
+    read_gen( gfile, 0, 0 );
+}
+
+void fini_ldpc_ ()
+{
+  mod2dense_free (G);
+  mod2sparse_free (U);
+  mod2sparse_free (L);
+  free (cols);
+  free (rows);
+  mod2sparse_free (H);
+}