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/* -*- 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_viterbi_b.h>
#include <gr_io_signature.h>
#include <assert.h>
#include <iostream>
static const float INF = 1.0e9;
trellis_viterbi_b_sptr
trellis_make_viterbi_b (
const fsm &FSM,
const int K,
const int S0,
const int SK)
{
return trellis_viterbi_b_sptr (new trellis_viterbi_b (FSM,K,S0,SK));
}
trellis_viterbi_b::trellis_viterbi_b (
const fsm &FSM,
const int K,
const int S0,
const int SK)
: gr_block ("viterbi_b",
gr_make_io_signature (1, -1, sizeof (float)),
gr_make_io_signature (1, -1, sizeof (unsigned char))),
d_FSM (FSM),
d_K (K),
d_S0 (S0),
d_SK (SK),
d_trace(FSM.S()*K)
{
set_relative_rate (1.0 / ((double) d_FSM.O()));
set_output_multiple (d_K);
}
void
trellis_viterbi_b::forecast (int noutput_items, gr_vector_int &ninput_items_required)
{
assert (noutput_items % d_K == 0);
int input_required = d_FSM.O() * noutput_items ;
unsigned ninputs = ninput_items_required.size();
for (unsigned int i = 0; i < ninputs; i++) {
ninput_items_required[i] = input_required;
}
}
void viterbi_algorithm(const int I, const int S, const int O,
const std::vector<int> &NS,
const std::vector<int> &OS,
const std::vector<int> &PS,
const std::vector<int> &PI,
const int K,
const int S0,const int SK,
const float *in, unsigned char *out,
std::vector<int> &trace)
{
std::vector<float> alpha(S*2);
int alphai;
float norm,mm,minm;
int minmi;
int st;
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;
}
alphai=0;
for(int k=0;k<K;k++) {
norm=INF;
for(int j=0;j<S;j++) { // for each next state do ACS
minm=INF;
minmi=0;
for(int i=0;i<I;i++) {
int i0 = j*I+i;
if((mm=alpha[alphai*S+PS[i0]]+in[k*O+OS[PS[i0]*I+PI[i0]]])<minm)
minm=mm,minmi=i;
}
trace[k*S+j]=minmi;
alpha[((alphai+1)%2)*S+j]=minm;
if(minm<norm) norm=minm;
}
for(int j=0;j<S;j++)
alpha[((alphai+1)%2)*S+j]-=norm; // normalize total metrics so they do not explode
alphai=(alphai+1)%2;
}
if(SK<0) { // final state not specified
minm=INF;
minmi=0;
for(int i=0;i<S;i++)
if((mm=alpha[alphai*S+i])<minm) minm=mm,minmi=i;
st=minmi;
}
else {
st=SK;
}
for(int k=K-1;k>=0;k--) { // traceback
int i0=st*I+trace[k*S+st];
out[k]= (unsigned char) PI[i0];
st=PS[i0];
}
}
int
trellis_viterbi_b::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() == output_items.size());
int nstreams = input_items.size();
assert (noutput_items % d_K == 0);
int nblocks = noutput_items / d_K;
for (int m=0;m<nstreams;m++) {
const float *in = (const float *) input_items[m];
unsigned char *out = (unsigned char *) output_items[m];
for (int n=0;n<nblocks;n++) {
viterbi_algorithm(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,&(in[n*d_K*d_FSM.O()]),&(out[n*d_K]),d_trace);
}
}
consume_each (d_FSM.O() * noutput_items );
return noutput_items;
}
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