/* -*- 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.
 */

#include "selective_fading_model_impl.h"
#include <gnuradio/io_signature.h>
#include <iostream>

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

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


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


namespace gr {
  namespace channels {

    selective_fading_model::sptr
    selective_fading_model::make( unsigned int N, float fDTs, bool LOS, float K, int seed, std::vector<float> delays, std::vector<float> mags, int ntaps)
    {
      return gnuradio::get_initial_sptr
	(new selective_fading_model_impl( N, fDTs, LOS, K, seed, delays, mags, ntaps));
    }

    // Block constructor
    selective_fading_model_impl::selective_fading_model_impl( unsigned int N, float fDTs, bool LOS, float K, int seed, std::vector<float> delays, std::vector<float> mags, int ntaps )
      : sync_block("selective_fading_model",
		       io_signature::make(1, 1, sizeof(gr_complex)),
		       io_signature::make(1, 1, sizeof(gr_complex))),
        d_delays(delays),
        d_mags(mags),
        d_sintable(1024)
    {
        if(mags.size() != delays.size())
            throw std::runtime_error("magnitude and delay vectors must be the same length!");

        for(size_t i=0; i<mags.size(); i++){
            d_faders.push_back(new gr::channels::flat_fader_impl(N, fDTs, (i==0)&&(LOS), K, seed+i));
        }

        // set up tap history
        if(ntaps < 1){ throw std::runtime_error("ntaps must be >= 1"); }
        set_history(1+ntaps);
        d_taps.resize(ntaps, gr_complex(0,0));
    }

    selective_fading_model_impl::~selective_fading_model_impl()
    {
        for(size_t i=0; i<d_faders.size(); i++){
            delete d_faders[i];
        }
    }

    int
    selective_fading_model_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];

        // loop over each output sample
        for(int i=0; i<noutput_items; i++){

            // clear the current values in each tap
            for(size_t j=0; j<d_taps.size(); j++){
                d_taps[j] = gr_complex(0,0);
            }

            // add each flat fading component to the taps
            for(size_t j=0; j<d_faders.size(); j++){
                gr_complex ff_H(d_faders[j]->next_sample());
                for(size_t k=0; k<d_taps.size(); k++){
                    float dist = k-d_delays[j];
                    float interpmag = d_sintable.sinc(M_PI*dist);
                    d_taps[k] += ff_H * interpmag * d_mags[j];
                }
            }

            // apply the taps and generate output
            gr_complex sum(0,0);
            for(size_t j=0; j<d_taps.size(); j++){
                sum += in[i+j] * d_taps[d_taps.size()-j-1];
            }

            // assign output
            out[i] = sum;
        }

        // return all outputs
        return noutput_items;
    }

    void
    selective_fading_model_impl::setup_rpc()
    {
#ifdef GR_CTRLPORT
    add_rpc_variable(
        rpcbasic_sptr(new rpcbasic_register_get<selective_fading_model, float >(
            alias(), "fDTs",
            &selective_fading_model::fDTs,
            pmt::mp(0), pmt::mp(1), pmt::mp(0.01),
            "Hz*Sec", "normalized maximum doppler frequency (fD*Ts)",
            RPC_PRIVLVL_MIN, DISPTIME | DISPOPTSTRIP)));
    add_rpc_variable(
        rpcbasic_sptr(new rpcbasic_register_set<selective_fading_model, float >(
            alias(), "fDTs",
            &selective_fading_model::set_fDTs,
            pmt::mp(0), pmt::mp(1), pmt::mp(0.01),
            "Hz*Sec", "normalized maximum doppler frequency (fD*Ts)",
            RPC_PRIVLVL_MIN, DISPTIME | DISPOPTSTRIP)));

    add_rpc_variable(
        rpcbasic_sptr(new rpcbasic_register_get<selective_fading_model, float >(
            alias(), "K",
            &selective_fading_model::K,
            pmt::mp(0), pmt::mp(8), pmt::mp(4),
            "Ratio", "Rician factor (ratio of the specular power to the scattered power)",
            RPC_PRIVLVL_MIN, DISPTIME | DISPOPTSTRIP)));
    add_rpc_variable(
        rpcbasic_sptr(new rpcbasic_register_set<selective_fading_model, float >(
            alias(), "K",
            &selective_fading_model::set_K,
            pmt::mp(0), pmt::mp(8), pmt::mp(4),
            "Ratio", "Rician factor (ratio of the specular power to the scattered power)",
            RPC_PRIVLVL_MIN, DISPTIME | DISPOPTSTRIP)));

    add_rpc_variable(
        rpcbasic_sptr(new rpcbasic_register_get<selective_fading_model, float >(
            alias(), "step",
            &selective_fading_model::step,
            pmt::mp(0), pmt::mp(8), pmt::mp(4),
            "radians", "Maximum step size for random walk angle per sample",
            RPC_PRIVLVL_MIN, DISPTIME | DISPOPTSTRIP)));
    add_rpc_variable(
        rpcbasic_sptr(new rpcbasic_register_set<selective_fading_model, float >(
            alias(), "step",
            &selective_fading_model::set_step,
            pmt::mp(0), pmt::mp(1), pmt::mp(0.00001),
            "radians", "Maximum step size for random walk angle per sample",
            RPC_PRIVLVL_MIN, DISPTIME | DISPOPTSTRIP)));
#endif /* GR_CTRLPORT */
    }

  } /* namespace channels */
} /* namespace gr */