/* -*- c++ -*- */

/*

 * Copyright 2007 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., 51 Franklin Street,

 * Boston, MA 02110-1301, USA.

 */

#ifdef HAVE_CONFIG_H

#include "config.h"

#endif

#include <gr_dpll_bb.h>

#include <gr_io_signature.h>

gr_dpll_bb_sptr

gr_make_dpll_bb (float period, float gain)

{

  return gr_dpll_bb_sptr (new gr_dpll_bb (period, gain));

}

gr_dpll_bb::gr_dpll_bb (float period, float gain)

  : gr_sync_block ("dpll_bb",

                   gr_make_io_signature (1, 1, sizeof (char)),

                   gr_make_io_signature (1, 1, sizeof (char))),

    d_restart(0),d_pulse_phase(0)

{

  d_pulse_frequency = 1.0/period;

  d_gain = gain;

  d_decision_threshold = 1.0 - 0.5*d_pulse_frequency;

#if 1

  fprintf(stderr,"frequency = %f period = %f gain = %f threshold = %f\n",

          d_pulse_frequency,

          period,

          d_gain,

          d_decision_threshold);

#endif

  set_history(1); // so we can look behind us

}

int

gr_dpll_bb::work (int noutput_items,

              gr_vector_const_void_star &input_items,

              gr_vector_void_star &output_items)

{

  const char *iptr = (const char *) input_items[0];

  char *optr = (char *) output_items[0];

  for (int i = 0; i < noutput_items; i++){

    optr[i]= 0;

    if(iptr[i] == 1) {

      if (d_restart == 0) {

        d_pulse_phase = 1;

      } else {

        if (d_pulse_phase > 0.5) d_pulse_phase += d_gain*(1.0-d_pulse_phase);

        else d_pulse_phase -= d_gain*d_pulse_phase;

      }

      d_restart = 3;

    }

    if (d_pulse_phase > d_decision_threshold) {

      d_pulse_phase -= 1.0;

      if (d_restart > 0) {

        d_restart -= 1;

        optr[i] = 1;

      }

    }

    d_pulse_phase += d_pulse_frequency;

  }

  return noutput_items;

}