Added trellis_constellation_metrics_cf. It is equivalent to trellis_metrics_c but it uses the constellation object's calc_metric method. This method is also added here. trellis_metric_type.h is moved to gr_metric_type since constellation object is now dependent on it.

5 files changed, 88 insertions, 0 deletions

diff --git a/gnuradio-core/src/lib/general/Makefile.am b/gnuradio-core/src/lib/general/Makefile.am
index e5ea49640..0830f5d2e 100644
--- a/gnuradio-core/src/lib/general/Makefile.am
+++ b/gnuradio-core/src/lib/general/Makefile.am
@@ -266,6 +266,7 @@ grinclude_HEADERS = 			\
 	gr_log2_const.h			\
 	gr_map_bb.h			\
 	gr_math.h			\
+	gr_metric_type.h		\
 	gr_misc.h			\
 	gr_nco.h			\
 	gr_nlog10_ff.h			\
diff --git a/gnuradio-core/src/lib/general/gr_constellation.cc b/gnuradio-core/src/lib/general/gr_constellation.cc
index 403394eaa..8f5624668 100644
--- a/gnuradio-core/src/lib/general/gr_constellation.cc
+++ b/gnuradio-core/src/lib/general/gr_constellation.cc
@@ -22,11 +22,14 @@
 
 #include <gr_io_signature.h>
 #include <gr_constellation.h>
+#include <gr_metric_type.h>
 #include <gr_math.h>
 #include <gr_complex.h>
 #include <math.h>
 #include <iostream>
 #include <stdlib.h>
+#include <float.h>
+#include <stdexcept>
 
 #define M_TWOPI (2*M_PI)
 #define SQRT_TWO 0.707107
@@ -76,6 +79,45 @@ unsigned int gr_constellation::decision_maker(gr_complex sample)
   return min_index;
 }
 
+void gr_constellation::calc_metric(gr_complex sample, float *metric, trellis_metric_type_t type) {
+  switch (type){
+  case TRELLIS_EUCLIDEAN:
+    calc_euclidean_metric(sample, metric);
+    break;
+  case TRELLIS_HARD_SYMBOL:
+    calc_hard_symbol_metric(sample, metric);
+    break;
+  case TRELLIS_HARD_BIT:
+    throw std::runtime_error ("Invalid metric type (not yet implemented).");
+    break;
+  default:
+    throw std::runtime_error ("Invalid metric type.");
+  }
+}
+
+void gr_constellation::calc_euclidean_metric(gr_complex sample, float *metric) {
+  for (int o=0; o<d_constellation.size(); o++) {
+    gr_complex s = sample - d_constellation[o];
+    metric[o] = s.real()*s.real()+s.imag()*s.imag();
+  }
+}
+
+void gr_constellation::calc_hard_symbol_metric(gr_complex sample, float *metric){
+  float minm = FLT_MAX;
+  int minmi = 0;
+  for (int o=0; o<d_constellation.size(); o++) {
+    gr_complex s = sample - d_constellation[o];
+    float dist = s.real()*s.real()+s.imag()*s.imag();
+    if (dist < minm) {
+      minm = dist;
+      minmi = o;
+    }
+  }
+  for(int o=0; o<d_constellation.size(); o++) {
+    metric[o] = (o==minmi?0.0:1.0);
+  }
+}
+
 gr_constellation_sector::gr_constellation_sector (std::vector<gr_complex> constellation,
 						  unsigned int n_sectors) :
   gr_constellation(constellation),
diff --git a/gnuradio-core/src/lib/general/gr_constellation.h b/gnuradio-core/src/lib/general/gr_constellation.h
index 8ba22d59a..6908f43f1 100644
--- a/gnuradio-core/src/lib/general/gr_constellation.h
+++ b/gnuradio-core/src/lib/general/gr_constellation.h
@@ -27,6 +27,7 @@
 #include <math.h>
 #include <gr_complex.h>
 #include <boost/enable_shared_from_this.hpp>
+#include <gr_metric_type.h>
 
 /************************************************************/
 /* gr_constellation                                         */
@@ -55,9 +56,19 @@ class gr_constellation : public boost::enable_shared_from_this<gr_constellation>
   //! Also calculates the phase error.
   virtual unsigned int decision_maker (gr_complex sample);
   
+  //! Calculates metrics for all points in the constellation.
+  //! For use with the viterbi algorithm.
+  void calc_metric(gr_complex sample, float *metric, trellis_metric_type_t type);
+  void calc_euclidean_metric(gr_complex sample, float *metric);
+  void calc_hard_symbol_metric(gr_complex sample, float *metric);
+  
   unsigned int bits_per_symbol () {
     return floor(log(d_constellation.size())/log(2));
   }
+  
+  unsigned int arity () {
+    return d_constellation.size();
+  }
 
   gr_constellation_sptr base() {
     return shared_from_this();
diff --git a/gnuradio-core/src/lib/general/gr_constellation.i b/gnuradio-core/src/lib/general/gr_constellation.i
index 6620721ea..d00c62f90 100644
--- a/gnuradio-core/src/lib/general/gr_constellation.i
+++ b/gnuradio-core/src/lib/general/gr_constellation.i
@@ -23,6 +23,9 @@
 %template(gr_complex_vector) std::vector<gr_complex>;
 %template(unsigned_int_vector) std::vector<unsigned int>;
 
+// Make sure metric types get SWIGed.
+%include gr_metric_type.h
+
 class gr_constellation;
 typedef boost::shared_ptr<gr_constellation> gr_constellation_sptr;
 %template(gr_constellation_sptr) boost::shared_ptr<gr_constellation>;
diff --git a/gnuradio-core/src/lib/general/gr_metric_type.h b/gnuradio-core/src/lib/general/gr_metric_type.h
new file mode 100644
index 000000000..74c93b55e
--- /dev/null
+++ b/gnuradio-core/src/lib/general/gr_metric_type.h
@@ -0,0 +1,31 @@
+/* -*- c++ -*- */
+/*
+ * Copyright 2004 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.
+ */
+
+#ifndef INCLUDED_GR_METRIC_TYPE_H
+#define INCLUDED_GR_METRIC_TYPE_H
+
+typedef enum {
+  TRELLIS_EUCLIDEAN = 200, TRELLIS_HARD_SYMBOL, TRELLIS_HARD_BIT
+} trellis_metric_type_t;
+
+#endif
+