Houston, we have a trunk.

git-svn-id: http://gnuradio.org/svn/gnuradio/trunk@3122 221aa14e-8319-0410-a670-987f0aec2ac5

1 files changed, 100 insertions, 0 deletions

diff --git a/gr-atsc/src/lib/atsci_single_viterbi.cc b/gr-atsc/src/lib/atsci_single_viterbi.cc
new file mode 100644
index 000000000..edc2cd13b
--- /dev/null
+++ b/gr-atsc/src/lib/atsci_single_viterbi.cc
@@ -0,0 +1,100 @@
+/* -*- 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 2, 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., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#include <math.h>
+#include <atsci_single_viterbi.h>
+#include <iostream>
+
+using std::cerr;
+using std::cout;
+
+const float atsci_single_viterbi::was_sent[32] = {
+  -7,-3,-7,-3,-7,-3,-7,-3,
+  -5,-1,-5,-1,-5,-1,-5,-1,
+  1,5,1,5,1,5,1,5,
+  3,7,3,7,3,7,3,7
+};
+
+const int atsci_single_viterbi::transition_table[32] = {
+  0,2,4,6,
+  2,0,6,4,
+  1,3,5,7,
+  3,1,7,5,
+  4,6,0,2,
+  6,4,2,0,
+  5,7,1,3,
+  7,5,3,1
+};
+
+void
+atsci_single_viterbi::reset()
+{
+  for (unsigned int i = 0; i<2; i++)
+    for (unsigned int j = 0; j<8; j++) {
+      path_metrics[i][j] = 0;
+      traceback[i][j] = 0;
+    }
+  phase = 0;
+}
+
+atsci_single_viterbi::atsci_single_viterbi()
+{
+  reset();
+}
+
+char
+atsci_single_viterbi::decode(float input)
+{
+  for (unsigned int next_state = 0; next_state < 8; next_state++) {
+    unsigned int index = next_state << 2;
+    int min_metric_symb = 0;
+    float min_metric = fabs(input - was_sent[index + 0]) +
+      path_metrics[phase][transition_table[index + 0]];
+
+    for (unsigned int symbol_sent = 1; symbol_sent < 4; symbol_sent++) 
+      if( (fabs(input-was_sent[index+symbol_sent]) + 
+	   path_metrics[phase][transition_table[index+symbol_sent]])
+	  < min_metric) {
+	min_metric = fabs(input-was_sent[index+symbol_sent]) + 
+	  path_metrics[phase][transition_table[index+symbol_sent]];
+	min_metric_symb = symbol_sent;
+      }
+
+    path_metrics[phase^1][next_state] = min_metric;
+    traceback[phase^1][next_state] = (((unsigned long long)min_metric_symb) << 62) |
+      (traceback[phase][transition_table[index+min_metric_symb]] >> 2);
+  }
+  unsigned int best_state = 0;
+  float best_state_metric = path_metrics[phase^1][0];
+  for (unsigned int state = 1; state < 8; state++)
+    if(path_metrics[phase^1][state] < best_state_metric) {
+      best_state = state;
+      best_state_metric = path_metrics[phase^1][state];
+    }
+  if(best_state_metric > 10000) {
+    for(unsigned int state = 0; state < 8; state++)
+      path_metrics[phase^1][state] -= best_state_metric;
+    // cerr << "Resetting Path Metrics from " << best_state_metric << " to 0\n";
+  }
+  phase ^= 1;
+  return (0x3 & traceback[phase][best_state]);
+}