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

/*

 * Copyright 2009 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_decimator_ccf.h>

#include <gr_fir_ccf.h>

#include <gr_fir_util.h>

#include <gri_fft.h>

#include <gr_io_signature.h>

#include <gr_expj.h>

gr_pfb_decimator_ccf_sptr gr_make_pfb_decimator_ccf (unsigned int decim, 

                                                     const std::vector<float> &taps,

                                                     unsigned int channel)

{

  return gr_pfb_decimator_ccf_sptr (new gr_pfb_decimator_ccf (decim, taps, channel));

}

gr_pfb_decimator_ccf::gr_pfb_decimator_ccf (unsigned int decim, 

                                            const std::vector<float> &taps,

                                            unsigned int channel)

  : gr_sync_block ("pfb_decimator_ccf",

                   gr_make_io_signature (decim, decim, sizeof(gr_complex)),

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

    d_updated (false)

{

  d_rate = decim;

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

  d_chan = channel;

  d_rotator = new gr_complex[d_rate];

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

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

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

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

    d_rotator[i] = gr_expj(i*2*M_PI*d_chan/d_rate);

  }

  // Now, actually set the filters' taps

  set_taps(taps);

  // Create the FFT to handle the output de-spinning of the channels

  d_fft = new gri_fft_complex (d_rate, false);

}

gr_pfb_decimator_ccf::~gr_pfb_decimator_ccf ()

{

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

    delete d_filters[i];

  }

}

void

gr_pfb_decimator_ccf::set_taps (const std::vector<float> &taps)

{

  unsigned int i,j;

  unsigned int ntaps = taps.size();

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

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

  d_taps.resize(d_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 = taps;

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

    tmp_taps.push_back(0.0);

  }

  // Partition the filter

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

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

    d_taps[i] = std::vector<float>(d_taps_per_filter, 0);

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

      d_taps[i][j] = tmp_taps[i + j*d_rate];  // add taps to channels in reverse order

    }

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

    d_filters[i]->set_taps(d_taps[i]);

  }

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

  set_history (d_taps_per_filter);

  d_updated = true;

}

void

gr_pfb_decimator_ccf::print_taps()

{

  unsigned int i, j;

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

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

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

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

    }

    printf("]\n\n");

  }

}

#define ROTATEFFT

int

gr_pfb_decimator_ccf::work (int noutput_items,

                            gr_vector_const_void_star &input_items,

                            gr_vector_void_star &output_items)

{

  gr_complex *in;

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

  if (d_updated) {

    d_updated = false;

    return 0;                     // history requirements may have changed.

  }

  int i;

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

    // Move through filters from bottom to top

    out[i] = 0;

    for(int j = d_rate-1; j >= 0; j--) {

      // Take in the items from the first input stream to d_rate

      in = (gr_complex*)input_items[d_rate - 1 - j];

      // Filter current input stream from bottom filter to top

      // The rotate them by expj(j*k*2pi/M) where M is the number of filters

      // (the decimation rate) and k is the channel number to extract

      // This is the real math that goes on; we abuse the FFT to do this quickly

      // for decimation rates > N where N is a small number (~5):

      //       out[i] += d_filters[j]->filter(&in[i])*gr_expj(j*d_chan*2*M_PI/d_rate);

#ifdef ROTATEFFT

      d_fft->get_inbuf()[j] = d_filters[j]->filter(&in[i]);

#else

      out[i] += d_filters[j]->filter(&in[i])*d_rotator[i];

#endif

    }

#ifdef ROTATEFFT

    // Perform the FFT to do the complex multiply despinning for all channels

    d_fft->execute();

    // Select only the desired channel out

    out[i] = d_fft->get_outbuf()[d_chan];

#endif

  }

  return noutput_items;

}