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

/*

 * Copyright 2004,2007 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 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_fractional_interpolator_ff.h>

#include <gri_mmse_fir_interpolator.h>

#include <stdexcept>

// Public constructor

gr_fractional_interpolator_ff_sptr gr_make_fractional_interpolator_ff(float phase_shift, float interp_ratio)

{

  return gr_fractional_interpolator_ff_sptr(new gr_fractional_interpolator_ff(phase_shift, interp_ratio));

}

gr_fractional_interpolator_ff::gr_fractional_interpolator_ff(float phase_shift, float interp_ratio)

  : gr_block ("fractional_interpolator_ff",

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

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

    d_mu (phase_shift), d_mu_inc (interp_ratio), d_interp(new gri_mmse_fir_interpolator())

{

  if (interp_ratio <=  0)

    throw std::out_of_range ("interpolation ratio must be > 0");

  if (phase_shift <  0  || phase_shift > 1)

    throw std::out_of_range ("phase shift ratio must be > 0 and < 1");

  set_relative_rate (1.0 / interp_ratio);

}

gr_fractional_interpolator_ff::~gr_fractional_interpolator_ff()

{

  delete d_interp;

}

void

gr_fractional_interpolator_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_mu_inc) + d_interp->ntaps());

}

int

gr_fractional_interpolator_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

  while (oo < noutput_items) {

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

    double s = d_mu + d_mu_inc;

    double f = floor (s);

    int incr = (int) f;

    d_mu = s - f;

    ii += incr;

  }

  consume_each (ii);

  return noutput_items;

}