Added a siso_combined block analogous to the viterbi_combined; useful for FSMs with a large output alphabet

git-svn-id: http://gnuradio.org/svn/gnuradio/trunk@3452 221aa14e-8319-0410-a670-987f0aec2ac5

7 files changed, 559 insertions, 21 deletions

diff --git a/gr-trellis/src/lib/Makefile.am b/gr-trellis/src/lib/Makefile.am
index 767f603a2..7c9b23166 100644
--- a/gr-trellis/src/lib/Makefile.am
+++ b/gr-trellis/src/lib/Makefile.am
@@ -70,6 +70,7 @@ _trellis_la_SOURCES = 			\
         trellis_calc_metric.cc		\
         trellis_permutation.cc		\
 	trellis_siso_f.cc		\
+	trellis_siso_combined_f.cc	\
 	$(GENERATED_CC)                 
 
 # magic flags
@@ -96,6 +97,7 @@ grinclude_HEADERS =			\
         trellis_permutation.h		\
         trellis_siso_type.h		\
 	trellis_siso_f.h		\
+	trellis_siso_combined_f.h		\
 	$(GENERATED_H)                  
 
 
diff --git a/gr-trellis/src/lib/trellis.i b/gr-trellis/src/lib/trellis.i
index 983576e83..6f00f8c38 100644
--- a/gr-trellis/src/lib/trellis.i
+++ b/gr-trellis/src/lib/trellis.i
@@ -11,6 +11,7 @@
 #include "interleaver.h"
 #include "trellis_permutation.h"
 #include "trellis_siso_f.h"
+#include "trellis_siso_combined_f.h"
 #include <stdexcept>
 %}
 
@@ -20,6 +21,7 @@
 %include "interleaver.i"
 %include "trellis_permutation.i"
 %include "trellis_siso_f.i"
+%include "trellis_siso_combined_f.i"
 
 %include "trellis_metric_type.h"
 %include "trellis_siso_type.h"
diff --git a/gr-trellis/src/lib/trellis_siso_combined_f.cc b/gr-trellis/src/lib/trellis_siso_combined_f.cc
new file mode 100644
index 000000000..61cf6f8bf
--- /dev/null
+++ b/gr-trellis/src/lib/trellis_siso_combined_f.cc
@@ -0,0 +1,350 @@
+/* -*- 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 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.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <trellis_siso_combined_f.h>
+#include <gr_io_signature.h>
+#include <stdexcept>
+#include <assert.h>
+#include <iostream>
+  
+static const float INF = 1.0e9;
+
+trellis_siso_combined_f_sptr 
+trellis_make_siso_combined_f (
+    const fsm &FSM,
+    int K,
+    int S0,
+    int SK,
+    bool POSTI,
+    bool POSTO,
+    trellis_siso_type_t SISO_TYPE,
+    int D,
+    const std::vector<float> &TABLE,
+    trellis_metric_type_t TYPE)
+{
+  return trellis_siso_combined_f_sptr (new trellis_siso_combined_f (FSM,K,S0,SK,POSTI,POSTO,SISO_TYPE,D,TABLE,TYPE));
+}
+
+trellis_siso_combined_f::trellis_siso_combined_f (
+    const fsm &FSM,
+    int K,
+    int S0,
+    int SK,
+    bool POSTI,
+    bool POSTO,
+    trellis_siso_type_t SISO_TYPE,
+    int D,
+    const std::vector<float> &TABLE,
+    trellis_metric_type_t TYPE)
+  : gr_block ("siso_combined_f",
+			  gr_make_io_signature (1, -1, sizeof (float)),
+			  gr_make_io_signature (1, -1, sizeof (float))),  
+  d_FSM (FSM),
+  d_K (K),
+  d_S0 (S0),
+  d_SK (SK),
+  d_POSTI (POSTI),
+  d_POSTO (POSTO),
+  d_SISO_TYPE (SISO_TYPE),
+  d_D (D),
+  d_TABLE (TABLE),
+  d_TYPE (TYPE)//,
+  //d_alpha(FSM.S()*(K+1)),
+  //d_beta(FSM.S()*(K+1))
+{
+    int multiple;
+    if (d_POSTI && d_POSTO) 
+        multiple = d_FSM.I()+d_FSM.O();
+    else if(d_POSTI)
+        multiple = d_FSM.I();
+    else if(d_POSTO)
+        multiple = d_FSM.O();
+    else
+        throw std::runtime_error ("Not both POSTI and POSTO can be false.");
+    //printf("constructor: Multiple = %d\n",multiple);
+    set_output_multiple (d_K*multiple);
+    //what is the meaning of relative rate for a block with 2 inputs?
+    //set_relative_rate ( multiple / ((double) d_FSM.I()) );
+    // it turns out that the above gives problems in the scheduler, so 
+    // let's try (assumption O>I)
+    //set_relative_rate ( multiple / ((double) d_FSM.O()) );
+    // I am tempted to automate like this
+    if(d_FSM.I() <= d_D)
+      set_relative_rate ( multiple / ((double) d_D) );
+    else
+      set_relative_rate ( multiple / ((double) d_FSM.I()) ); 
+}
+
+
+void
+trellis_siso_combined_f::forecast (int noutput_items, gr_vector_int &ninput_items_required)
+{
+  int multiple;
+  if (d_POSTI && d_POSTO)
+      multiple = d_FSM.I()+d_FSM.O();
+  else if(d_POSTI)
+      multiple = d_FSM.I();
+  else if(d_POSTO)
+      multiple = d_FSM.O();
+  else
+      throw std::runtime_error ("Not both POSTI and POSTO can be false.");
+  //printf("forecast: Multiple = %d\n",multiple); 
+  assert (noutput_items % (d_K*multiple) == 0);
+  int input_required1 =  d_FSM.I() * (noutput_items/multiple) ;
+  int input_required2 =  d_D * (noutput_items/multiple) ;
+  //printf("forecast: Output requirements:  %d\n",noutput_items);
+  //printf("forecast: Input requirements:  %d   %d\n",input_required1,input_required2);
+  unsigned ninputs = ninput_items_required.size();
+  assert(ninputs % 2 == 0);
+  for (unsigned int i = 0; i < ninputs/2; i++) {
+    ninput_items_required[2*i] = input_required1;
+    ninput_items_required[2*i+1] = input_required2;
+  }
+}
+
+inline float min(float a, float b)
+{
+  return a <= b ? a : b;
+}
+
+inline float min_star(float a, float b)
+{
+  return (a <= b ? a : b)-log(1+exp(a <= b ? a-b : b-a));
+}
+
+void siso_algorithm_combined(int I, int S, int O, 
+             const std::vector<int> &NS,
+             const std::vector<int> &OS,
+             const std::vector<int> &PS,
+             const std::vector<int> &PI,
+             int K,
+             int S0,int SK,
+             bool POSTI, bool POSTO,
+             float (*p2mymin)(float,float),
+             int D,
+             const std::vector<float> &TABLE,
+             trellis_metric_type_t TYPE,
+             const float *priori, const float *observations, float *post//,
+             //std::vector<float> &alpha,
+             //std::vector<float> &beta
+             ) 
+{
+  float norm,mm,minm;
+  std::vector<float> alpha(S*(K+1));
+  std::vector<float> beta(S*(K+1));
+  float *prioro = new float[O*K];
+
+
+  if(S0<0) { // initial state not specified
+      for(int i=0;i<S;i++) alpha[0*S+i]=0;
+  }
+  else {
+      for(int i=0;i<S;i++) alpha[0*S+i]=INF;
+      alpha[0*S+S0]=0.0;
+  }
+
+  for(int k=0;k<K;k++) { // forward recursion
+      calc_metric_f(O, D, TABLE, &(observations[k*D]), &(prioro[k*O]),TYPE); // calc metrics
+      norm=INF;
+      for(int j=0;j<S;j++) {
+          minm=INF;
+          for(int i=0;i<I;i++) {
+              int i0 = j*I+i;
+              mm=alpha[k*S+PS[i0]]+priori[k*I+PI[i0]]+prioro[k*O+OS[PS[i0]*I+PI[i0]]];
+              minm=(*p2mymin)(minm,mm);
+          }
+          alpha[(k+1)*S+j]=minm;
+          if(minm<norm) norm=minm;
+      }
+      for(int j=0;j<S;j++) 
+          alpha[(k+1)*S+j]-=norm; // normalize total metrics so they do not explode
+  }
+
+  if(SK<0) { // final state not specified
+      for(int i=0;i<S;i++) beta[K*S+i]=0;
+  }
+  else {
+      for(int i=0;i<S;i++) beta[K*S+i]=INF;
+      beta[K*S+SK]=0.0;
+  }
+
+  for(int k=K-1;k>=0;k--) { // backward recursion
+      norm=INF;
+      for(int j=0;j<S;j++) { 
+          minm=INF;
+          for(int i=0;i<I;i++) {
+              int i0 = j*I+i;
+              mm=beta[(k+1)*S+NS[i0]]+priori[k*I+i]+prioro[k*O+OS[i0]];
+              minm=(*p2mymin)(minm,mm);
+          }
+          beta[k*S+j]=minm;
+          if(minm<norm) norm=minm;
+      }
+      for(int j=0;j<S;j++)
+          beta[k*S+j]-=norm; // normalize total metrics so they do not explode
+  }
+
+
+  if (POSTI && POSTO)
+  {
+    for(int k=0;k<K;k++) { // input combining
+        norm=INF;
+        for(int i=0;i<I;i++) {
+            minm=INF;
+            for(int j=0;j<S;j++) {
+                mm=alpha[k*S+j]+prioro[k*O+OS[j*I+i]]+beta[(k+1)*S+NS[j*I+i]];
+                minm=(*p2mymin)(minm,mm);
+            }
+            post[k*(I+O)+i]=minm;
+            if(minm<norm) norm=minm;
+        }
+        for(int i=0;i<I;i++)
+            post[k*(I+O)+i]-=norm; // normalize metrics
+    }
+
+
+    for(int k=0;k<K;k++) { // output combining
+        norm=INF;
+        for(int n=0;n<O;n++) {
+            minm=INF;
+            for(int j=0;j<S;j++) {
+                for(int i=0;i<I;i++) {
+                    mm= (n==OS[j*I+i] ? alpha[k*S+j]+priori[k*I+i]+beta[(k+1)*S+NS[j*I+i]] : INF);
+                    minm=(*p2mymin)(minm,mm);
+                }
+            }
+            post[k*(I+O)+I+n]=minm;
+            if(minm<norm) norm=minm;
+        }
+        for(int n=0;n<O;n++)
+            post[k*(I+O)+I+n]-=norm; // normalize metrics
+    }
+  } 
+  else if(POSTI) 
+  {
+    for(int k=0;k<K;k++) { // input combining
+        norm=INF;
+        for(int i=0;i<I;i++) {
+            minm=INF;
+            for(int j=0;j<S;j++) {
+                mm=alpha[k*S+j]+prioro[k*O+OS[j*I+i]]+beta[(k+1)*S+NS[j*I+i]];
+                minm=(*p2mymin)(minm,mm);
+            }
+            post[k*I+i]=minm;
+            if(minm<norm) norm=minm;
+        }
+        for(int i=0;i<I;i++)
+            post[k*I+i]-=norm; // normalize metrics
+    }
+  }
+  else if(POSTO)
+  {
+    for(int k=0;k<K;k++) { // output combining
+        norm=INF;
+        for(int n=0;n<O;n++) {
+            minm=INF;
+            for(int j=0;j<S;j++) {
+                for(int i=0;i<I;i++) {
+                    mm= (n==OS[j*I+i] ? alpha[k*S+j]+priori[k*I+i]+beta[(k+1)*S+NS[j*I+i]] : INF);
+                    minm=(*p2mymin)(minm,mm);
+                }
+            }
+            post[k*O+n]=minm;
+            if(minm<norm) norm=minm;
+        }
+        for(int n=0;n<O;n++)
+            post[k*O+n]-=norm; // normalize metrics
+    }
+  }
+  else
+    throw std::runtime_error ("Not both POSTI and POSTO can be false.");
+
+  delete [] prioro;
+
+}
+
+
+
+
+
+
+int
+trellis_siso_combined_f::general_work (int noutput_items,
+                        gr_vector_int &ninput_items,
+                        gr_vector_const_void_star &input_items,
+                        gr_vector_void_star &output_items)
+{
+  assert (input_items.size() == 2*output_items.size());
+  int nstreams = output_items.size();
+  //printf("general_work:Streams:  %d\n",nstreams); 
+  int multiple;
+  if (d_POSTI && d_POSTO)
+      multiple = d_FSM.I()+d_FSM.O();
+  else if(d_POSTI)
+      multiple = d_FSM.I();
+  else if(d_POSTO)
+      multiple = d_FSM.O();
+  else
+      throw std::runtime_error ("Not both POSTI and POSTO can be false.");
+
+  assert (noutput_items % (d_K*multiple) == 0);
+  int nblocks = noutput_items / (d_K*multiple);
+  //printf("general_work:Blocks:  %d\n",nblocks); 
+  //for(int i=0;i<ninput_items.size();i++)
+      //printf("general_work:Input items available:  %d\n",ninput_items[i]);
+
+  float (*p2min)(float, float) = NULL; 
+  if(d_SISO_TYPE == TRELLIS_MIN_SUM)
+    p2min = &min;
+  else if(d_SISO_TYPE == TRELLIS_SUM_PRODUCT)
+    p2min = &min_star;
+
+
+  for (int m=0;m<nstreams;m++) {
+    const float *in1 = (const float *) input_items[2*m];
+    const float *in2 = (const float *) input_items[2*m+1];
+    float *out = (float *) output_items[m];
+    for (int n=0;n<nblocks;n++) {
+      siso_algorithm_combined(d_FSM.I(),d_FSM.S(),d_FSM.O(),
+        d_FSM.NS(),d_FSM.OS(),d_FSM.PS(),d_FSM.PI(),
+        d_K,d_S0,d_SK,
+        d_POSTI,d_POSTO,
+        p2min,
+        d_D,d_TABLE,d_TYPE,
+        &(in1[n*d_K*d_FSM.I()]),&(in2[n*d_K*d_D]),
+        &(out[n*d_K*multiple])//,
+        //d_alpha,d_beta
+        );
+    }
+  }
+
+  for (unsigned int i = 0; i < input_items.size()/2; i++) {
+    consume(2*i,d_FSM.I() * noutput_items / multiple );
+    consume(2*i+1,d_D * noutput_items / multiple );
+  }
+
+  return noutput_items;
+}
diff --git a/gr-trellis/src/lib/trellis_siso_combined_f.h b/gr-trellis/src/lib/trellis_siso_combined_f.h
new file mode 100644
index 000000000..f6d24e593
--- /dev/null
+++ b/gr-trellis/src/lib/trellis_siso_combined_f.h
@@ -0,0 +1,109 @@
+/* -*- 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 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.
+ */
+
+#ifndef INCLUDED_TRELLIS_SISO_COMBINED_F_H
+#define INCLUDED_TRELLIS_SISO_COMBINED_F_H
+
+#include "fsm.h"
+#include "trellis_siso_type.h"
+#include "trellis_calc_metric.h"
+#include <gr_block.h>
+
+class trellis_siso_combined_f;
+typedef boost::shared_ptr<trellis_siso_combined_f> trellis_siso_combined_f_sptr;
+
+trellis_siso_combined_f_sptr trellis_make_siso_combined_f (
+    const fsm &FSM, 	// underlying FSM
+    int K,		// block size in trellis steps
+    int S0,		// initial state (put -1 if not specified)
+    int SK,		// final state (put -1 if not specified)
+    bool POSTI,		// true if you want a-posteriori info about the input symbols to be mux-ed in the output
+    bool POSTO,		// true if you want a-posteriori info about the output symbols to be mux-ed in the output
+    trellis_siso_type_t d_SISO_TYPE, // perform "min-sum" or "sum-product" combining 
+    int D,
+    const std::vector<float> &TABLE,
+    trellis_metric_type_t TYPE
+);
+
+
+
+class trellis_siso_combined_f : public gr_block
+{
+  fsm d_FSM;
+  int d_K;
+  int d_S0;
+  int d_SK;
+  bool d_POSTI;
+  bool d_POSTO;
+  trellis_siso_type_t d_SISO_TYPE;
+  int d_D;
+  std::vector<float> d_TABLE;
+  trellis_metric_type_t d_TYPE;
+  //std::vector<float> d_alpha;
+  //std::vector<float> d_beta;
+
+  friend trellis_siso_combined_f_sptr trellis_make_siso_combined_f (
+    const fsm &FSM,
+    int K,
+    int S0,
+    int SK,
+    bool POSTI,
+    bool POSTO,
+    trellis_siso_type_t d_SISO_TYPE,
+    int D,
+    const std::vector<float> &TABLE,
+    trellis_metric_type_t TYPE);
+
+
+  trellis_siso_combined_f (
+    const fsm &FSM,
+    int K,
+    int S0,
+    int SK,
+    bool POSTI,
+    bool POSTO,
+    trellis_siso_type_t d_SISO_TYPE,
+    int D,
+    const std::vector<float> &TABLE,
+    trellis_metric_type_t TYPE);
+
+
+public:
+  fsm FSM () const { return d_FSM; }
+  int K () const { return d_K; }
+  int S0 () const { return d_S0; }
+  int SK () const { return d_SK; }
+  bool POSTI () const { return d_POSTI; }
+  bool POSTO () const { return d_POSTO; }
+  trellis_siso_type_t SISO_TYPE () const { return d_SISO_TYPE; }
+  int D () const { return d_D; }
+  std::vector<float> TABLE () const { return d_TABLE; }
+  trellis_metric_type_t TYPE () const { return d_TYPE; }
+  void forecast (int noutput_items,
+                 gr_vector_int &ninput_items_required);
+  int general_work (int noutput_items,
+                    gr_vector_int &ninput_items,
+                    gr_vector_const_void_star &input_items,
+                    gr_vector_void_star &output_items);
+};
+
+#endif
diff --git a/gr-trellis/src/lib/trellis_siso_combined_f.i b/gr-trellis/src/lib/trellis_siso_combined_f.i
new file mode 100644
index 000000000..840afabc2
--- /dev/null
+++ b/gr-trellis/src/lib/trellis_siso_combined_f.i
@@ -0,0 +1,64 @@
+/* -*- 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 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.
+ */
+
+GR_SWIG_BLOCK_MAGIC(trellis,siso_combined_f);
+
+trellis_siso_combined_f_sptr trellis_make_siso_combined_f (
+    const fsm &FSM,
+    int K,
+    int S0,
+    int SK,
+    bool POSTI,
+    bool POSTO,
+    trellis_siso_type_t SISO_TYPE,
+    int D,
+    const std::vector<float> &TABLE,
+    trellis_metric_type_t TYPE);
+
+
+class trellis_siso_combined_f : public gr_block
+{
+private:
+  trellis_siso_combined_f (
+    const fsm &FSM,
+    int K,
+    int S0,
+    int SK,
+    bool POSTI,
+    bool POSTO,
+    trellis_siso_type_t SISO_TYPE,
+    int D,
+    const std::vector<float> &TABLE,
+    trellis_metric_type_t TYPE);
+
+public:
+    fsm FSM () const { return d_FSM; }
+    int K () const { return d_K; }
+    int S0 () const { return d_S0; }
+    int SK () const { return d_SK; }
+    bool POSTI () const { return d_POSTI; }
+    bool POSTO () const { return d_POSTO; }
+    trellis_siso_type_t SISO_TYPE () const { return d_SISO_TYPE; }
+    int D () const { return d_D; }
+    std::vector<float> TABLE () const { return d_TABLE; }
+    trellis_metric_type_t TYPE () const { return d_TYPE; }
+};
diff --git a/gr-trellis/src/lib/trellis_siso_f.cc b/gr-trellis/src/lib/trellis_siso_f.cc
index df364fc65..6d8548194 100644
--- a/gr-trellis/src/lib/trellis_siso_f.cc
+++ b/gr-trellis/src/lib/trellis_siso_f.cc
@@ -62,9 +62,9 @@ trellis_siso_f::trellis_siso_f (
   d_SK (SK),
   d_POSTI (POSTI),
   d_POSTO (POSTO),
-  d_SISO_TYPE (SISO_TYPE),
-  d_alpha(FSM.S()*(K+1)),
-  d_beta(FSM.S()*(K+1))
+  d_SISO_TYPE (SISO_TYPE)//,
+  //d_alpha(FSM.S()*(K+1)),
+  //d_beta(FSM.S()*(K+1))
 {
     int multiple;
     if (d_POSTI && d_POSTO) 
@@ -77,10 +77,16 @@ trellis_siso_f::trellis_siso_f (
         throw std::runtime_error ("Not both POSTI and POSTO can be false.");
     //printf("constructor: Multiple = %d\n",multiple);
     set_output_multiple (d_K*multiple);
-    //what is the meaning of relative rate for this?
-    // it was suggested to use the one furthest from 1.0
-    // let's do it.
-    set_relative_rate ( multiple / ((double) d_FSM.I()) );
+    //what is the meaning of relative rate for a block with 2 inputs?
+    //set_relative_rate ( multiple / ((double) d_FSM.I()) );
+    // it turns out that the above gives problems in the scheduler, so 
+    // let's try (assumption O>I)
+    //set_relative_rate ( multiple / ((double) d_FSM.O()) );
+    // I am tempted to automate like this
+    if(d_FSM.I() <= d_FSM.O())
+      set_relative_rate ( multiple / ((double) d_FSM.O()) );
+    else
+      set_relative_rate ( multiple / ((double) d_FSM.I()) ); 
 }
 
 
@@ -129,11 +135,14 @@ void siso_algorithm(int I, int S, int O,
              int S0,int SK,
              bool POSTI, bool POSTO,
              float (*p2mymin)(float,float),
-             const float *priori, const float *prioro, float *post,
-             std::vector<float> &alpha,
-             std::vector<float> &beta) 
+             const float *priori, const float *prioro, float *post//,
+             //std::vector<float> &alpha,
+             //std::vector<float> &beta
+             ) 
 {
   float norm,mm,minm;
+  std::vector<float> alpha(S*(K+1));
+  std::vector<float> beta(S*(K+1));
 
 
   if(S0<0) { // initial state not specified
@@ -309,8 +318,9 @@ trellis_siso_f::general_work (int noutput_items,
         d_POSTI,d_POSTO,
         p2min,
         &(in1[n*d_K*d_FSM.I()]),&(in2[n*d_K*d_FSM.O()]),
-        &(out[n*d_K*multiple]),
-        d_alpha,d_beta);
+        &(out[n*d_K*multiple])//,
+        //d_alpha,d_beta
+        );
     }
   }
 
diff --git a/gr-trellis/src/lib/trellis_siso_f.h b/gr-trellis/src/lib/trellis_siso_f.h
index 36981254d..4c2f41f4e 100644
--- a/gr-trellis/src/lib/trellis_siso_f.h
+++ b/gr-trellis/src/lib/trellis_siso_f.h
@@ -31,13 +31,14 @@ class trellis_siso_f;
 typedef boost::shared_ptr<trellis_siso_f> trellis_siso_f_sptr;
 
 trellis_siso_f_sptr trellis_make_siso_f (
-    const fsm &FSM, 
-    int K,
-    int S0,
-    int SK,
-    bool POSTI,
-    bool POSTO,
-    trellis_siso_type_t d_SISO_TYPE);
+    const fsm &FSM, 	// underlying FSM
+    int K,		// block size in trellis steps
+    int S0,		// initial state (put -1 if not specified)
+    int SK,		// final state (put -1 if not specified)
+    bool POSTI,		// true if you want a-posteriori info about the input symbols to be mux-ed in the output
+    bool POSTO,		// true if you want a-posteriori info about the output symbols to be mux-ed in the output
+    trellis_siso_type_t d_SISO_TYPE // perform "min-sum" or "sum-product" combining 
+);
 
 
 
@@ -50,8 +51,8 @@ class trellis_siso_f : public gr_block
   bool d_POSTI;
   bool d_POSTO;
   trellis_siso_type_t d_SISO_TYPE;
-  std::vector<float> d_alpha;
-  std::vector<float> d_beta;
+  //std::vector<float> d_alpha;
+  //std::vector<float> d_beta;
 
   friend trellis_siso_f_sptr trellis_make_siso_f (
     const fsm &FSM,