/* -*- c++ -*- */
/*
 * Copyright 2008,2010,2012,2018 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 "fmdet_cf_impl.h"
#include <gnuradio/io_signature.h>
#include <gnuradio/math.h>

namespace gr {
namespace analog {

fmdet_cf::sptr
fmdet_cf::make(float samplerate, float freq_low, float freq_high, float scl)
{
    return gnuradio::get_initial_sptr(
        new fmdet_cf_impl(samplerate, freq_low, freq_high, scl));
}

fmdet_cf_impl::fmdet_cf_impl(float samplerate, float freq_low, float freq_high, float scl)
    : sync_block("fmdet_cf",
                 io_signature::make(1, 1, sizeof(gr_complex)),
                 io_signature::make(1, 1, sizeof(float))),
      d_S1(0.1),
      d_S2(0.1),
      d_S3(0.1),
      d_S4(0.1)
{
    d_freq = 0;
    d_freqhi = freq_high;
    d_freqlo = freq_low;
    set_scale(scl);
}

fmdet_cf_impl::~fmdet_cf_impl() {}

void fmdet_cf_impl::set_scale(float scl)
{
    float delta = d_freqhi - d_freqlo;
    d_scl = scl;
    d_bias = 0.5 * scl * (d_freqhi + d_freqlo) / delta;
}

void fmdet_cf_impl::set_freq_range(float freq_low, float freq_high)
{
    d_freqhi = freq_high;
    d_freqlo = freq_low;
    set_scale(d_scl);
}

int fmdet_cf_impl::work(int noutput_items,
                        gr_vector_const_void_star& input_items,
                        gr_vector_void_star& output_items)
{
    const gr_complex* iptr = (gr_complex*)input_items[0];
    float* optr = (float*)output_items[0];

    int size = noutput_items;

    gr_complex Sdot, S0;
    gr_complex S1 = d_S1, S2 = d_S2, S3 = d_S3, S4 = d_S4;

    while (size-- > 0) {
        S0 = *iptr++;

        Sdot = d_scl * (-S0 + 8.f * S1 - 8.f * S3 + S4);

        d_freq = (S2.real() * Sdot.imag() - S2.imag() * Sdot.real()) /
                 (S2.real() * S2.real() + S2.imag() * S2.imag());

        S4 = S3;
        S3 = S2;
        S2 = S1;
        S1 = S0;

        *optr++ = d_freq - d_bias;
    }
    d_S1 = S1;
    d_S2 = S2;
    d_S3 = S3;
    d_S4 = S4;
    return noutput_items;
}

} /* namespace analog */
} /* namespace gr */
