/* -*- c++ -*- */
/*
 * Copyright 2014 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 "msk_timing_recovery_cc_impl.h"
#include <gnuradio/filter/firdes.h>
#include <gnuradio/io_signature.h>
#include <gnuradio/math.h>

namespace gr {
namespace digital {

msk_timing_recovery_cc::sptr
msk_timing_recovery_cc::make(float sps, float gain, float limit, int osps = 1)
{
    return gnuradio::get_initial_sptr(
        new msk_timing_recovery_cc_impl(sps, gain, limit, osps));
}

/*
 * The private constructor
 */
msk_timing_recovery_cc_impl::msk_timing_recovery_cc_impl(float sps,
                                                         float gain,
                                                         float limit,
                                                         int osps)
    : gr::block("msk_timing_recovery_cc",
                gr::io_signature::make(1, 1, sizeof(gr_complex)),
                gr::io_signature::make3(
                    1, 3, sizeof(gr_complex), sizeof(float), sizeof(float))),
      d_limit(limit),
      d_interp(new filter::mmse_fir_interpolator_cc()),
      d_dly_conj_1(0),
      d_dly_conj_2(0),
      d_dly_diff_1(0),
      d_mu(0.5),
      d_div(0),
      d_osps(osps)
{
    set_sps(sps);
    enable_update_rate(true); // fixes tag propagation through variable rate blox
    set_gain(gain);
    if (d_osps != 1 && d_osps != 2)
        throw std::out_of_range("osps must be 1 or 2");
}

msk_timing_recovery_cc_impl::~msk_timing_recovery_cc_impl() { delete d_interp; }

void msk_timing_recovery_cc_impl::set_sps(float sps)
{
    d_sps = sps / 2.0; // loop runs at 2x sps
    d_omega = d_sps;
    set_relative_rate(d_osps / sps);
    //        set_history(d_sps);
}

float msk_timing_recovery_cc_impl::get_sps(void) { return d_sps; }

void msk_timing_recovery_cc_impl::set_gain(float gain)
{
    d_gain = gain;
    if (d_gain <= 0)
        throw std::out_of_range("Gain must be positive");
    d_gain_omega = d_gain * d_gain * 0.25;
}

float msk_timing_recovery_cc_impl::get_gain(void) { return d_gain; }

void msk_timing_recovery_cc_impl::set_limit(float limit) { d_limit = limit; }

float msk_timing_recovery_cc_impl::get_limit(void) { return d_limit; }

void msk_timing_recovery_cc_impl::forecast(int noutput_items,
                                           gr_vector_int& ninput_items_required)
{
    unsigned ninputs = ninput_items_required.size();
    for (unsigned i = 0; i < ninputs; i++) {
        ninput_items_required[i] =
            (int)ceil((noutput_items * d_sps * 2) + 3.0 * d_sps + d_interp->ntaps());
    }
}

int msk_timing_recovery_cc_impl::general_work(int noutput_items,
                                              gr_vector_int& ninput_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];
    float *out2, *out3;
    if (output_items.size() >= 2)
        out2 = (float*)output_items[1];
    if (output_items.size() >= 3)
        out3 = (float*)output_items[2];
    int oidx = 0, iidx = 0;
    int ninp = ninput_items[0] - 3.0 * d_sps;
    if (ninp <= 0) {
        consume_each(0);
        return (0);
    }

    std::vector<tag_t> tags;
    get_tags_in_range(
        tags, 0, nitems_read(0), nitems_read(0) + ninp, pmt::intern("time_est"));

    gr_complex sq,     // Squared input
        dly_conj,      // Input delayed sps and conjugated
        nlin_out,      // output of the nonlinearity
        in_interp;     // interpolated input
    float err_out = 0; // error output

    while (oidx < noutput_items && iidx < ninp) {
        // check to see if there's a tag to reset the timing estimate
        if (!tags.empty()) {
            int offset = tags[0].offset - nitems_read(0);
            if ((offset >= iidx) && (offset < (iidx + d_sps))) {
                float center = (float)pmt::to_double(tags[0].value);
                if (center != center) { // test for NaN, it happens somehow
                    tags.erase(tags.begin());
                    goto out;
                }
                if (std::abs(center) >= 1.0f) {
                    GR_LOG_WARN(d_logger,
                                boost::format("work: ignoring time_est tag "
                                              "(%.2f) outside of (-1, 1)") %
                                    center);
                    tags.erase(tags.begin());
                    goto out;
                }
                d_mu = center;
                iidx = offset;
                // we want positive mu, so offset iidx to compensate
                if (d_mu < 0) {
                    d_mu++;
                    iidx--;
                }
                d_div = 0;
                d_omega = d_sps;
                d_dly_conj_2 = d_dly_conj_1;
                // this keeps the block from outputting an odd number of
                // samples and throwing off downstream blocks which depend
                // on proper alignment -- for instance, a decimating FIR
                // filter.
                //                    if(d_div == 0 && d_osps == 2) oidx++;
                tags.erase(tags.begin());
            }
        }

    out:
        // the actual equation for the nonlinearity is as follows:
        // e(n) = in[n]^2 * in[n-sps].conj()^2
        // we then differentiate the error by subtracting the sample delayed by d_sps/2
        in_interp = d_interp->interpolate(&in[iidx], d_mu);
        sq = in_interp * in_interp;
        // conjugation is distributive.
        dly_conj = std::conj(d_dly_conj_2 * d_dly_conj_2);
        nlin_out = sq * dly_conj;
        // TODO: paper argues that some improvement can be had
        // if you either operate at >2sps or use a better numeric
        // differentiation method.
        err_out = std::real(nlin_out - d_dly_diff_1);
        if (d_div % 2) { // error loop calc once per symbol
            err_out = gr::branchless_clip(err_out, 3.0);
            d_omega += d_gain_omega * err_out;
            d_omega = d_sps + gr::branchless_clip(d_omega - d_sps, d_limit);
            d_mu += d_gain * err_out;
        }
        // output every other d_sps by default.
        if (!(d_div % 2) || d_osps == 2) {
            out[oidx] = in_interp;
            if (output_items.size() >= 2)
                out2[oidx] = err_out;
            if (output_items.size() >= 3)
                out3[oidx] = d_mu;
            oidx++;
        }
        d_div++;

        d_dly_conj_1 = in_interp;
        d_dly_conj_2 = d_dly_conj_1;
        d_dly_diff_1 = nlin_out;

        // update interpolator twice per symbol
        d_mu += d_omega;
        iidx += (int)floor(d_mu);
        d_mu -= floor(d_mu);
    }

    consume_each(iidx);
    return oidx;
}

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