fsm.h

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/* -*- c++ -*- */
/*
 * Copyright 2002,2011 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_TRELLIS_FSM_H
#define INCLUDED_TRELLIS_FSM_H

#include <trellis_api.h>
#include <vector>
#include <iosfwd>

/*!
 * \brief  Finite State Machine Specification class.
 *
 * An instance of this class represents a finite state machine specification (FSMS)
 * rather than the FSM itself.  It particular the state of the FSM
 * is not stored within an instance of this class.
 */
class TRELLIS_API fsm {
private:
  // Input alphabet cardinality.
  int d_I;
  // Number of states.
  int d_S;
  // Output alphabet cardinality.
  int d_O;
  // NS means Next State.
  // next_state = d_NS[current_state * d_I + input_symbol]
  std::vector<int> d_NS;
  // OS means Output Symbol.
  // output_symbol = d_OS[current_state * d_I + input_symbol]          
  std::vector<int> d_OS;
  // PS means Previous State.
  std::vector< std::vector<int> > d_PS;
  // PI means Previous Input Symbol.
  // d_PS[current_state][k] and d_PI[current_state][k], is a pair of the form
  // (previous_state, previous_input_symbol) that could have produced the
  // current state.
  std::vector< std::vector<int> > d_PI;
  // TM means Termination matrix.
  // d_TMl[s*d_S+es] is the shortest number of steps to get from state s to
  // state es.
  std::vector<int> d_TMl;
  // d_TMi[s*d_S+es] is the input symbol required to set off on the shortest
  // path from state s to es.
  std::vector<int> d_TMi;
  void generate_PS_PI ();
  void generate_TM ();
  bool find_es(int es);
public:
 /*!
   * \brief Constructor to create an uninitialized FSMS.
   */
  fsm();
 /*!
   * \brief Constructor to copy an FSMS.
   */
  fsm(const fsm &FSM);
 /*!
   * \brief Constructor to to create an FSMS.
   *
   * \param I           The number of possible input symbols.
   * \param S           The number of possible FSM states.
   * \param O           The number of possible output symbols.
   * \param NS          A mapping from (current state, input symbol) to next state.
   *                    next_state = NS[current_state * I + input_symbol]
   * \param OS          A mapping from (current state, input symbol) to output symbol.
   *                    output_symbol = OS[current_state * I + input_symbol]          
   *
   */
  fsm(int I, int S, int O, const std::vector<int> &NS, const std::vector<int> &OS);
 /*!
   * \brief Constructor to create an FSMS from file contents.
   *
   * \param name        filename
   *
   */
  fsm(const char *name);
 /*!
   * \brief Creates an FSMS from the generator matrix of a (n, k) binary convolutional code.
   *
   * \param k      ???
   * \param n      ???
   * \param G      ???
   *
   */
  fsm(int k, int n, const std::vector<int> &G);
  /*!
   * \brief Creates an FSMS describing ISI.
   *
   * \param mod_size    modulation size
   * \param ch_length   channel length
   *
   */
  fsm(int mod_size, int ch_length);
  /*!
   * \brief Creates an FSMS describing the trellis for a CPM.
   *
   * \param P    ???? h=K/P (relatively prime)
   * \param M    alphabet size
   * \param L    pulse duration
   *
   * This FSM is based on the paper by B. Rimoldi
   * "A decomposition approach to CPM", IEEE Trans. Info Theory, March 1988
   * See also my own notes at http://www.eecs.umich.edu/~anastas/docs/cpm.pdf
   */
  fsm(int P, int M, int L);
  /*!
   * \brief Creates an FSMS describing the joint trellis of two FSMs.
   *
   * \param FSM1  first FSMS
   * \param FSM2  second FSMS
   */
  fsm(const fsm &FSM1, const fsm &FSM2);
  /*!
   * \brief Creates an FSMS representing n stages through the originial FSM (AKA radix-n FSM).
   *
   * \param FSM      Original FSMs
   * \param n        Number of stages.
   */
  fsm(const fsm &FSM, int n);
  int I () const { return d_I; }
  int S () const { return d_S; }
  int O () const { return d_O; }
  const std::vector<int> & NS () const { return d_NS; }
  const std::vector<int> & OS () const { return d_OS; }
  const std::vector< std::vector<int> > & PS () const { return d_PS; }
  const std::vector< std::vector<int> > & PI () const { return d_PI; }
  const std::vector<int> & TMi () const { return d_TMi; }
  const std::vector<int> & TMl () const { return d_TMl; }
  /*!
   * \brief Creates an svg image of the trellis representation.
   *
   * \param filename         filename
   * \param number_stages    ????
   *
   */  
  void write_trellis_svg(std::string filename ,int number_stages);
  /*!
   * \brief Write the FSMS to a file.
   *
   * \param filename   filename
   *
   */
  void write_fsm_txt(std::string filename);
};

#endif