1 files changed, 284 insertions, 0 deletions
diff --git a/gr-atsc/lib/qa_atsci_single_viterbi.cc b/gr-atsc/lib/qa_atsci_single_viterbi.cc
new file mode 100644
index 0000000000..be5187dc25
--- /dev/null
+++ b/gr-atsc/lib/qa_atsci_single_viterbi.cc
@@ -0,0 +1,284 @@
+/* -*- c++ -*- */
+/*
+ * Copyright 2002 Free Software Foundation, Inc.
+ *
+ * This file is part of GNU Radio
+ *
+ * GNU Radio 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.
+ *
+ * GNU Radio 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 GNU Radio; see the file COPYING.  If not, write to
+ * the Free Software Foundation, Inc., 51 Franklin Street,
+ * Boston, MA 02110-1301, USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include <cppunit/TestAssert.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <atsc/single_viterbi_impl.h>
+#include "qa_atsci_single_viterbi.h"
+#include <random.h>
+#include <string.h>
+
+
+static const int NTRIALS     =   50;
+static const int MAXERRORS   =   10;
+static const int NN          =  200;
+
+static const int MAXDIBIT    = 3;
+
+void
+qa_atsci_single_viterbi::encode_block (unsigned char *out, unsigned char *in,
+				      unsigned int n)
+{
+  for (unsigned int i = 0; i < n; i++) {
+    out[i] = encoder.encode(in[i]);
+  }
+}
+
+
+void
+qa_atsci_single_viterbi::decode_block (unsigned char *out, unsigned char *in,
+				      unsigned int n, float noise_factor)
+{
+  for (unsigned int i = 0; i < n; i++) {
+    out[i] = decoder.decode((2*in[i]-7) + noise () * noise_factor);
+  }
+}
+
+float
+qa_atsci_single_viterbi::noise ()
+{
+  return 2.0 * ((float) random () / RANDOM_MAX - 0.5);	// uniformly (-1, 1)
+}
+
+void
+qa_atsci_single_viterbi::t0 ()
+{
+  static const int 			  blocklen = NN;
+  unsigned char		  in[blocklen];
+  unsigned char		  enc[blocklen];
+  unsigned char		  out[blocklen];
+  int			  decoder_errors = 0;
+  int			  delay = decoder.delay ();
+  int			  i;
+
+  // printf ("  Delay is %d.\n", delay);
+
+  srandom (27);		// reproducable sequence of "random" values
+
+  for (int nt = 0; nt < NTRIALS; nt++){
+
+    // load block with random data and encode
+
+    for (i = 0; i < (blocklen-delay); i++)
+      in[i] = random () & MAXDIBIT;
+    for (     ; i < blocklen; i++)
+      in[i] = 0;		/* To empty the delay buffers */
+
+    encoder.reset ();
+    encode_block (enc, in, blocklen);
+
+    decoder.reset ();
+
+    // decode the block
+    decode_block (out, enc, blocklen, 1.0);
+
+    // int offset = delay/4;
+    int offset = 2;
+    bool differs = (memcmp (in+offset,
+			    out+delay+offset, blocklen-(delay+offset)));
+
+    // initial values after reset are 0
+    for (i = 0; i < delay; i++){
+      if (out[i] != 0)
+	printf ("  initial output at %i is %X, not 0\n",
+		i, out[i]);
+    }
+
+    if (differs){
+      printf ("  incorrect data\n");
+
+      printf ("\n  Erroneous result dibits:");
+      for (int erri = 0; erri < (NN-delay); erri++) {
+	if (in[erri] != out[erri+delay])
+	  printf (" %d", erri);
+      }
+      printf ("\n  In:  ");
+      for (int erri = 0; erri < (NN-delay); erri++) {
+	printf (" %d", in[erri]);
+      }
+      printf ("\n  Out: ");
+      for (int erri = 0; erri < (NN-delay); erri++) {
+	printf (" %d", out[erri+delay]);
+      }
+      printf ("\n  Errs:");
+      for (int erri = 0; erri < (NN-delay); erri++) {
+	printf (" %c", (in[erri] != out[erri+delay])? '*': ' ');
+      }
+      printf ("\n    THIS IS A REAL PROBLEM.\n");
+      decoder_errors++;
+    }
+  }
+
+  printf ("  Summary: %d decoder errors out of %d trials.\n",
+	  decoder_errors, NTRIALS);
+
+  CPPUNIT_ASSERT (decoder_errors == 0);
+}
+
+void
+qa_atsci_single_viterbi::t1 ()
+{
+  static const int 			  blocklen = NN;
+  unsigned char		  in[blocklen];
+  unsigned char		  enc[blocklen];
+  unsigned char		  out[blocklen];
+  int			  errlocs[NN];
+  int			  errval;
+  int			  errloc;
+  int			  decoder_errors = 0;
+  int			  delay = decoder.delay ();
+  int			  i;
+
+  // printf ("  Delay is %d.\n", delay);
+
+  srandom (1);		// reproducable sequence of "random" values
+
+  for (int nt = 0; nt < NTRIALS; nt++){
+
+    // test up to the error correction capacity of the code
+    for (int errors = 0; errors <= MAXERRORS; errors++){
+
+      // load block with random data and encode
+
+      for (i = 0; i < (blocklen-delay); i++)
+	in[i] = random () & MAXDIBIT;
+      for (     ; i < blocklen; i++)
+	in[i] = 0;		/* To empty the delay buffers */
+
+      encoder.reset ();
+      encode_block (enc, in, blocklen);
+
+      // Now generate 0 to N errors in the encoded symbols.
+      //
+      //  If we restrict ourselves to damaging the low-order bit,
+      //  our decoder finds and fixes the vast majority of errors.
+      //
+      //  If we munge any or all of the three bits of the symbol,
+      //  our decoder frequently gets the wrong data even with a single
+      //  error.
+      //
+      //  Let's see what it can do with just the two low-order bits.
+      //
+      // ALSO:  Don't let any error be within 12 spots of another
+      //  error.  This simulates the muxed behavior.
+
+      memset (errlocs, 0, sizeof (errlocs));
+
+      for (int j = 0; j < errors; j++){
+
+	do {
+	  // errval = random () & 3;  // FIXME:  1;   // FIXME: MAXSYM;
+	  errval = random () & 1;  // FIXME:  1;   // FIXME: MAXSYM;
+	} while (errval == 0);	// error value must be non-zero
+
+	// Don't insert errors in the first delay slot, since we
+	// don't have valid history to correct them.  Also, don't
+	// insert burst errors (adjacent errors), or errors within 2,
+	// since we can't reliably correct them.  Also we must not choose
+	// the same location twice when inserting an error.
+
+	do {
+	  errloc = random () % NN;
+	} while (errloc < delay || errlocs[errloc] != 0
+		 || (errloc > 0 && errlocs[errloc-1] != 0)
+		 || (errloc > 1 && errlocs[errloc-2] != 0)
+		 || (errloc < (NN-1) && errlocs[errloc+1] != 0)
+		 || (errloc < (NN-2) && errlocs[errloc+2] != 0));
+
+	errlocs[errloc] = 1;
+
+	enc[errloc] ^= errval;		// cause the error
+      }
+
+      // decode the errored block
+      decoder.reset ();
+      decode_block (out, enc, blocklen, 0.5);
+
+      // int offset = delay/4;
+      int offset = 2;
+      bool differs = (memcmp (in+offset,
+			      out+delay+offset, blocklen-(delay+offset)));
+
+      // initial values after reset are 0
+      for (i = 0; i < delay; i++){
+	if (out[i] != 0)
+	  printf ("  initial output at %i is %X, not 0\n",
+		  i, out[i]);
+      }
+
+      if (differs){
+	printf ("  %2d errors introduced, %scorrect data\n",
+		 errors, differs? "in": "");
+
+	// FIXME, should we be able to tell how many errs too?
+        if (differs) {
+	  //const int ERRTOL = 12;		/* Or relate to delay? */
+	  int shouldfix = 1;
+	  //int lasti = -ERRTOL;
+
+	  printf (  "  Inserted errors:        ");
+	  for (int erri = 0; erri < NN; erri++) {
+	    if (errlocs[erri]) {
+	      printf (" %d", erri);
+	      // if (erri < lasti+ERRTOL)
+	      //   shouldfix = 0;
+	      //lasti = erri;
+	    }
+	  }
+	  printf ("\n  Erroneous result dibits:");
+	  for (int erri = 0; erri < (NN-delay); erri++) {
+	    if (in[erri] != out[erri+delay])
+	      printf (" %d", erri);
+	  }
+	  printf ("\n  In:  ");
+	  for (int erri = 0; erri < (NN-delay); erri++) {
+	      printf (" %d", in[erri]);
+	  }
+	  printf ("\n  Out: ");
+	  for (int erri = 0; erri < (NN-delay); erri++) {
+	      printf (" %d", out[erri+delay]);
+	  }
+	  printf ("\n  Errs:");
+	  for (int erri = 0; erri < (NN-delay); erri++) {
+	    printf (" %c", (in[erri] != out[erri+delay])? '*': ' ');
+	  }
+	  if (shouldfix)
+	    printf ("\n    THIS IS A REAL PROBLEM.\n");
+	  else
+	    printf ("\n    BUT THAT'S OK since errors are too close.\n");
+	  if (shouldfix)
+            decoder_errors++;
+	}
+      }
+    }
+  }
+
+  printf ("  Summary: %d decoder errors out of %d trials.\n",
+	  decoder_errors, (MAXERRORS*NTRIALS));
+
+  CPPUNIT_ASSERT (decoder_errors <= (MAXERRORS*NTRIALS) * .1);
+}