/* -*- c++ -*- */
/*
 * Copyright 2006,2007,2011,2012 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.
 */

#ifndef INCLUDED_DIGITAL_OFDM_FRAME_ACQUISITION_IMPL_H
#define INCLUDED_DIGITAL_OFDM_FRAME_ACQUISITION_IMPL_H

#include <gnuradio/digital/ofdm_frame_acquisition.h>

namespace gr {
namespace digital {

class ofdm_frame_acquisition_impl : public ofdm_frame_acquisition
{
private:
    unsigned char slicer(gr_complex x);
    void correlate(const gr_complex* symbol, int zeros_on_left);
    void calculate_equalizer(const gr_complex* symbol, int zeros_on_left);
    gr_complex coarse_freq_comp(int freq_delta, int count);

    unsigned int d_occupied_carriers; // !< \brief number of subcarriers with data
    unsigned int d_fft_length;        // !< \brief length of FFT vector
    unsigned int d_cplen;             // !< \brief length of cyclic prefix in samples
    unsigned int d_freq_shift_len; // !< \brief number of surrounding bins to look at for
                                   // correlation
    std::vector<gr_complex> d_known_symbol; // !< \brief known symbols at start of frame
    std::vector<float>
        d_known_phase_diff; // !< \brief factor used in correlation from known symbol
    std::vector<float>
        d_symbol_phase_diff; // !< \brief factor used in correlation from received symbol
    std::vector<gr_complex> d_hestimate; // !< channel estimate
    int d_coarse_freq;                   // !< \brief search distance in number of bins
    unsigned int d_phase_count; // !< \brief accumulator for coarse freq correction
    float d_snr_est;            // !< an estimation of the signal to noise ratio

    gr_complex* d_phase_lut; // !< look-up table for coarse frequency compensation

    void forecast(int noutput_items, gr_vector_int& ninput_items_required);

public:
    ofdm_frame_acquisition_impl(unsigned int occupied_carriers,
                                unsigned int fft_length,
                                unsigned int cplen,
                                const std::vector<gr_complex>& known_symbol,
                                unsigned int max_fft_shift_len = 4);
    ~ofdm_frame_acquisition_impl();

    /*!
     * \brief Return an estimate of the SNR of the channel
     */
    float snr() { return d_snr_est; }

    int general_work(int noutput_items,
                     gr_vector_int& ninput_items,
                     gr_vector_const_void_star& input_items,
                     gr_vector_void_star& output_items);
};

} /* namespace digital */
} /* namespace gr */

#endif /* INCLUDED_DIGITAL_OFDM_FRAME_ACQUISITION_IMPL_H */
