/* -*- c++ -*- */
/*
 * Copyright 2013 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 FLAT_FADER_IMPL_H
#define FLAT_FADER_IMPL_H

#include <gnuradio/io_signature.h>
#include <stdint.h>
#include <iostream>

#include <boost/format.hpp>
#include <boost/random.hpp>

#include "sincostable.h"
#include <gnuradio/fxpt.h>

// FASTSINCOS:  0 = slow native,  1 = gr::fxpt impl,  2 = sincostable.h
#define FASTSINCOS 2

namespace gr {
namespace channels {

class flat_fader_impl
{
private:
    // initial theta variate generator
    boost::mt19937 seed_1;
    boost::uniform_real<> dist_1; // U(-pi,pi)
    boost::variate_generator<boost::mt19937&, boost::uniform_real<>> rv_1;

    // random walk variate
    boost::mt19937 seed_2;
    boost::uniform_real<> dist_2; // U(0,1)
    boost::variate_generator<boost::mt19937&, boost::uniform_real<>> rv_2;

public:
    int d_N;        // number of sinusoids
    float d_fDTs;   // normalized maximum doppler frequency
    double d_theta; // random walk variable (RWP)
    float d_theta_los;
    float d_step; // maximum random walk step size
    uint64_t d_m; // sample counter

    float d_K;  // Rician factor (ratio of the specular power to the scattered power)
    bool d_LOS; // LOS path exists? chooses Rician (LOS) vs Rayleigh (NLOS) model.

    std::vector<float> d_psi; // in-phase initial phase
    std::vector<float> d_phi; // quadrature initial phase

    std::vector<float> d_costable;

    sincostable d_table;

    float scale_sin, scale_los, scale_nlos;

    void update_theta();

    flat_fader_impl(unsigned int N, float fDTs, bool LOS, float K, int seed);
    gr_complex next_sample();
    void next_samples(std::vector<gr_complex>& HVec, int n_samples);

}; /* class flat_fader_impl */
} /* namespace channels */
} /* namespace gr */

#endif // FLAT_FADER_IMPL_H
