/* -*- 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.

 */

#ifdef HAVE_CONFIG_H

#include "config.h"

#endif

#include <gr_io_signature.h>

#include <gr_clock_recovery_mm_ff.h>

#include <gri_mmse_fir_interpolator.h>

#include <stdexcept>

#define DEBUG_CR_MM_FF        0                // must be defined as 0 or 1

// Public constructor

gr_clock_recovery_mm_ff_sptr 

gr_make_clock_recovery_mm_ff(float omega, float gain_omega, float mu, float gain_mu,

                             float omega_relative_limit)

{

  return gr_clock_recovery_mm_ff_sptr (new gr_clock_recovery_mm_ff (omega,

                                                                    gain_omega, 

                                                                    mu,

                                                                    gain_mu,

                                                                    omega_relative_limit));

}

gr_clock_recovery_mm_ff::gr_clock_recovery_mm_ff (float omega, float gain_omega, float mu, float gain_mu,

                                                  float omega_relative_limit)

  : gr_block ("clock_recovery_mm_ff",

              gr_make_io_signature (1, 1, sizeof (float)),

              gr_make_io_signature (1, 1, sizeof (float))),

    d_mu (mu), d_gain_omega(gain_omega), d_gain_mu(gain_mu),

    d_last_sample(0), d_interp(new gri_mmse_fir_interpolator()),

    d_logfile(0), d_omega_relative_limit(omega_relative_limit)

{

  if (omega <  1)

    throw std::out_of_range ("clock rate must be > 0");

  if (gain_mu <  0  || gain_omega < 0)

    throw std::out_of_range ("Gains must be non-negative");

  set_omega(omega);                        // also sets min and max omega

  set_relative_rate (1.0 / omega);

  if (DEBUG_CR_MM_FF)

    d_logfile = fopen("cr_mm_ff.dat", "wb");

}

gr_clock_recovery_mm_ff::~gr_clock_recovery_mm_ff ()

{

  delete d_interp;

  if (DEBUG_CR_MM_FF && d_logfile){

    fclose(d_logfile);

    d_logfile = 0;

  }

}

void

gr_clock_recovery_mm_ff::forecast(int noutput_items, gr_vector_int &ninput_items_required)

{

  unsigned ninputs = ninput_items_required.size();

  for (unsigned i=0; i < ninputs; i++)

    ninput_items_required[i] =

      (int) ceil((noutput_items * d_omega) + d_interp->ntaps());

}

static inline float

slice(float x)

{

  return x < 0 ? -1.0F : 1.0F;

}

/*

 * This implements the Mueller and MÃŒller (M&M) discrete-time error-tracking synchronizer.

 *

 * See "Digital Communication Receivers: Synchronization, Channel

 * Estimation and Signal Processing" by Heinrich Meyr, Marc Moeneclaey, & Stefan Fechtel.

 * ISBN 0-471-50275-8.

 */

int

gr_clock_recovery_mm_ff::general_work (int noutput_items,

                                       gr_vector_int &ninput_items,

                                       gr_vector_const_void_star &input_items,

                                       gr_vector_void_star &output_items)

{

  const float *in = (const float *) input_items[0];

  float *out = (float *) output_items[0];

  int         ii = 0;                                // input index

  int          oo = 0;                                // output index

  float mm_val;

  while (oo < noutput_items){

    // produce output sample

    out[oo] = d_interp->interpolate (&in[ii], d_mu);

    mm_val = slice(d_last_sample) * out[oo] - slice(out[oo]) * d_last_sample;

    d_last_sample = out[oo];

    d_omega = d_omega + d_gain_omega * mm_val;

    if (d_omega > d_max_omega)

      d_omega = d_max_omega;

    else if (d_omega < d_min_omega)

      d_omega = d_min_omega;

    d_mu = d_mu + d_omega + d_gain_mu * mm_val;

    ii += (int) floor(d_mu);

    d_mu = d_mu - floor(d_mu);

    oo++;

    if (DEBUG_CR_MM_FF && d_logfile){

      fwrite(&d_omega, sizeof(d_omega), 1, d_logfile);

    }

  }

  consume_each (ii);

  return noutput_items;

}