/* -*- c++ -*- */
/*
 * Copyright 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.
 */

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

#include "cma_equalizer_cc_impl.h"
#include <gnuradio/io_signature.h>

namespace gr {
namespace digital {

using namespace filter::kernel;

cma_equalizer_cc::sptr
cma_equalizer_cc::make(int num_taps, float modulus, float mu, int sps)
{
    return gnuradio::get_initial_sptr(
        new cma_equalizer_cc_impl(num_taps, modulus, mu, sps));
}

cma_equalizer_cc_impl::cma_equalizer_cc_impl(int num_taps,
                                             float modulus,
                                             float mu,
                                             int sps)
    : sync_decimator("cma_equalizer_cc",
                     io_signature::make(1, 1, sizeof(gr_complex)),
                     io_signature::make(1, 1, sizeof(gr_complex)),
                     sps),
      fir_filter_ccc(sps, std::vector<gr_complex>(num_taps, gr_complex(0, 0))),
      d_new_taps(num_taps, gr_complex(0, 0)),
      d_updated(false),
      d_error(gr_complex(0, 0))
{
    set_modulus(modulus);
    set_gain(mu);
    if (num_taps > 0)
        d_new_taps[0] = 1.0;
    fir_filter_ccc::set_taps(d_new_taps);

    set_history(num_taps);
}

cma_equalizer_cc_impl::~cma_equalizer_cc_impl() {}

void cma_equalizer_cc_impl::set_taps(const std::vector<gr_complex>& taps)
{
    d_new_taps = taps;
    d_updated = true;
}

std::vector<gr_complex> cma_equalizer_cc_impl::taps() const { return d_taps; }

gr_complex cma_equalizer_cc_impl::error(const gr_complex& out)
{
    gr_complex error = out * (norm(out) - d_modulus);
    float re = gr::clip(error.real(), 1.0);
    float im = gr::clip(error.imag(), 1.0);
    return gr_complex(re, im);
}

void cma_equalizer_cc_impl::update_tap(gr_complex& tap, const gr_complex& in)
{
    // Hn+1 = Hn - mu*conj(Xn)*zn*(|zn|^2 - 1)
    tap -= d_mu * conj(in) * d_error;
}

int cma_equalizer_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];

    if (d_updated) {
        d_taps = d_new_taps;
        set_history(d_taps.size());
        d_updated = false;
        return 0; // history requirements may have changed.
    }

    int j = 0;
    size_t k, l = d_taps.size();
    for (int i = 0; i < noutput_items; i++) {
        out[i] = filter(&in[j]);

        // Adjust taps
        d_error = error(out[i]);
        for (k = 0; k < l; k++) {
            // Update tap locally from error.
            update_tap(d_taps[k], in[j + k]);

            // Update aligned taps in filter object.
            fir_filter_ccc::update_tap(d_taps[k], k);
        }

        j += decimation();
    }

    return noutput_items;
}

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