/* -*- c++ -*- */
/*
 * gr-satnogs: SatNOGS GNU Radio Out-Of-Tree Module
 *
 *  Copyright (C) 2016, Libre Space Foundation <http://librespacefoundation.org/>
 *
 *  This program 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 of the License, or
 *  (at your option) any later version.
 *
 *  This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <gnuradio/io_signature.h>
#include "coarse_doppler_correction_cc_impl.h"
#include <volk/volk.h>
#include <satnogs/log.h>

namespace gr {
namespace satnogs {

coarse_doppler_correction_cc::sptr
coarse_doppler_correction_cc::make(double target_freq,
                                   double offset,
                                   double sampling_rate)
{
  return gnuradio::get_initial_sptr(
           new coarse_doppler_correction_cc_impl(target_freq, offset,
               sampling_rate));
}

/*
 * The private constructor
 */
coarse_doppler_correction_cc_impl::coarse_doppler_correction_cc_impl(
  double target_freq, double offset, double sampling_rate) :
  gr::sync_block("coarse_doppler_correction_cc",
                 gr::io_signature::make(1, 1, sizeof(gr_complex)),
                 gr::io_signature::make(1, 1, sizeof(gr_complex))),
  d_target_freq(target_freq),
  d_offset(offset),
  d_samp_rate(sampling_rate),
  d_buf_items(std::min((size_t)8192UL, (size_t)(d_samp_rate / 4))),
  d_freq_diff(d_offset),
  d_nco()
{
  message_port_register_in(pmt::mp("freq"));

  /*
   * NOTE:
   * Set the maximum number of samples to be equivalent of half a second.
   * With this way we are sure that at least one frequency message
   * per second will be processed.
   *
   * This is taken into consideration due to the fact that the work()
   * and the input message handler are NOT reentrant.
   */
  set_max_noutput_items(d_samp_rate / 4.0);
  set_alignment(8);

  set_msg_handler(
    pmt::mp("freq"),
    boost::bind(&coarse_doppler_correction_cc_impl::new_freq, this, _1));

  d_nco.set_freq((2 * M_PI * (-d_freq_diff)) / d_samp_rate);
  /* Allocate aligned memory for the NCO */
  d_nco_buff = (gr_complex *) volk_malloc(
                 (d_samp_rate / 4) * sizeof(gr_complex), 32);
  if (!d_nco_buff) {
    throw std::runtime_error("Could not allocate NCO memory");
  }
}

void
coarse_doppler_correction_cc_impl::new_freq(pmt::pmt_t msg)
{
  double new_freq;
  new_freq = pmt::to_double(msg);
  d_freq_diff = new_freq - (d_target_freq - d_offset);
  d_nco.set_freq((2 * M_PI * (-d_freq_diff)) / d_samp_rate);
}

/*
 * Our virtual destructor.
 */
coarse_doppler_correction_cc_impl::~coarse_doppler_correction_cc_impl()
{
  volk_free(d_nco_buff);
}

int
coarse_doppler_correction_cc_impl::work(
  int noutput_items, gr_vector_const_void_star &input_items,
  gr_vector_void_star &output_items)
{
  const gr_complex *in = (const gr_complex *) input_items[0];
  gr_complex *out = (gr_complex *) output_items[0];

  /* Perform the correction */
  d_nco.sincos(d_nco_buff, noutput_items, 1.0);
  volk_32fc_x2_multiply_32fc(out, in, d_nco_buff, noutput_items);

  // Tell runtime system how many output items we produced.
  return noutput_items;
}

} /* namespace satnogs */
} /* namespace gr */