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

/*

 * Copyright 2009,2010 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_pfb_arb_resampler_ccf.h>

#include <gr_fir_ccf.h>

#include <gr_fir_util.h>

#include <gr_io_signature.h>

#include <cstdio>

gr_pfb_arb_resampler_ccf_sptr gr_make_pfb_arb_resampler_ccf (float rate, 

                                                             const std::vector<float> &taps,

                                                             unsigned int filter_size)

{

  return gnuradio::get_initial_sptr(new gr_pfb_arb_resampler_ccf (rate, taps,

                                                                  filter_size));

}

gr_pfb_arb_resampler_ccf::gr_pfb_arb_resampler_ccf (float rate, 

                                                    const std::vector<float> &taps,

                                                    unsigned int filter_size)

  : gr_block ("pfb_arb_resampler_ccf",

              gr_make_io_signature (1, 1, sizeof(gr_complex)),

              gr_make_io_signature (1, 1, sizeof(gr_complex))),

    d_updated (false)

{

  d_acc = 0; // start accumulator at 0

  /* The number of filters is specified by the user as the filter size;

     this is also the interpolation rate of the filter. We use it and the

     rate provided to determine the decimation rate. This acts as a

     rational resampler. The flt_rate is calculated as the residual

     between the integer decimation rate and the real decimation rate and

     will be used to determine to interpolation point of the resampling

     process.

  */

  d_int_rate = filter_size;

  set_rate(rate);

  // Store the last filter between calls to work

  d_last_filter = 0;

  d_start_index = 0;

  d_filters = std::vector<gr_fir_ccf*>(d_int_rate);

  d_diff_filters = std::vector<gr_fir_ccf*>(d_int_rate);

  // Create an FIR filter for each channel and zero out the taps

  std::vector<float> vtaps(0, d_int_rate);

  for(unsigned int i = 0; i < d_int_rate; i++) {

    d_filters[i] = gr_fir_util::create_gr_fir_ccf(vtaps);

    d_diff_filters[i] = gr_fir_util::create_gr_fir_ccf(vtaps);

  }

  // Now, actually set the filters' taps

  std::vector<float> dtaps;

  create_diff_taps(taps, dtaps);

  create_taps(taps, d_taps, d_filters);

  create_taps(dtaps, d_dtaps, d_diff_filters);

}

gr_pfb_arb_resampler_ccf::~gr_pfb_arb_resampler_ccf ()

{

  for(unsigned int i = 0; i < d_int_rate; i++) {

    delete d_filters[i];

  }

}

void

gr_pfb_arb_resampler_ccf::create_taps (const std::vector<float> &newtaps,

                                       std::vector< std::vector<float> > &ourtaps,

                                       std::vector<gr_fir_ccf*> &ourfilter)

{

  unsigned int ntaps = newtaps.size();

  d_taps_per_filter = (unsigned int)ceil((double)ntaps/(double)d_int_rate);

  // Create d_numchan vectors to store each channel's taps

  ourtaps.resize(d_int_rate);

  // Make a vector of the taps plus fill it out with 0's to fill

  // each polyphase filter with exactly d_taps_per_filter

  std::vector<float> tmp_taps;

  tmp_taps = newtaps;

  while((float)(tmp_taps.size()) < d_int_rate*d_taps_per_filter) {

    tmp_taps.push_back(0.0);

  }

  // Partition the filter

  for(unsigned int i = 0; i < d_int_rate; i++) {

    // Each channel uses all d_taps_per_filter with 0's if not enough taps to fill out

    ourtaps[d_int_rate-1-i] = std::vector<float>(d_taps_per_filter, 0);

    for(unsigned int j = 0; j < d_taps_per_filter; j++) {

      ourtaps[d_int_rate - 1 - i][j] = tmp_taps[i + j*d_int_rate];

    }

    // Build a filter for each channel and add it's taps to it

    ourfilter[i]->set_taps(ourtaps[d_int_rate-1-i]);

  }

  // Set the history to ensure enough input items for each filter

  set_history (d_taps_per_filter + 1);

  d_updated = true;

}

void

gr_pfb_arb_resampler_ccf::create_diff_taps(const std::vector<float> &newtaps,

                                           std::vector<float> &difftaps)

{

  // Calculate the differential taps (derivative filter) by taking the difference

  // between two taps. Duplicate the last one to make both filters the same length.

  float tap;

  difftaps.clear();

  for(unsigned int i = 0; i < newtaps.size()-1; i++) {

    tap = newtaps[i+1] - newtaps[i];

    difftaps.push_back(tap);

  }

  difftaps.push_back(tap);

}

void

gr_pfb_arb_resampler_ccf::print_taps()

{

  unsigned int i, j;

  for(i = 0; i < d_int_rate; i++) {

    printf("filter[%d]: [", i);

    for(j = 0; j < d_taps_per_filter; j++) {

      printf(" %.4e", d_taps[i][j]);

    }

    printf("]\n");

  }

}

int

gr_pfb_arb_resampler_ccf::general_work (int noutput_items,

                                        gr_vector_int &ninput_items,

                                        gr_vector_const_void_star &input_items,

                                        gr_vector_void_star &output_items)

{

  gr_complex *in = (gr_complex *) input_items[0];

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

  if (d_updated) {

    d_updated = false;

    return 0;                     // history requirements may have changed.

  }

  int i = 0, count = d_start_index;

  unsigned int j;

  gr_complex o0, o1;

  // Restore the last filter position

  j = d_last_filter;

  // produce output as long as we can and there are enough input samples

  int max_input = ninput_items[0]-(int)d_taps_per_filter;

  while((i < noutput_items) && (count < max_input)) {

    // start j by wrapping around mod the number of channels

    while((j < d_int_rate) && (i < noutput_items)) {

      // Take the current filter and derivative filter output

      o0 = d_filters[j]->filter(&in[count]);

      o1 = d_diff_filters[j]->filter(&in[count]);

      out[i] = o0 + o1*d_acc;     // linearly interpolate between samples

      i++;

      // Adjust accumulator and index into filterbank

      d_acc += d_flt_rate;

      j += d_dec_rate + (int)floor(d_acc);

      d_acc = fmodf(d_acc, 1.0);

    }

    if(i < noutput_items) {              // keep state for next entry

      float ss = (int)(j / d_int_rate);  // number of items to skip ahead by

      count += ss;                       // we have fully consumed another input

      j = j % d_int_rate;                // roll filter around

    }

  }

  // Store the current filter position and start of next sample

  d_last_filter = j;

  d_start_index = std::max(0, count - ninput_items[0]);

  // consume all we've processed but no more than we can

  consume_each(std::min(count, ninput_items[0]));

  return i;

}