/* -*- c++ -*- */
/*
 * Copyright 2004,2010,2012,2019 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 "wvps_ff_impl.h"
#include <gnuradio/io_signature.h>
#include <string.h>

namespace gr {
namespace wavelet {

static int ceil_log2(int k)
{
    int m = 0;
    for (int n = k - 1; n > 0; n >>= 1)
        m++;
    return m;
}

wvps_ff::sptr wvps_ff::make(int ilen)
{
    return gnuradio::get_initial_sptr(new wvps_ff_impl(ilen));
}

wvps_ff_impl::wvps_ff_impl(int ilen)
    : sync_block("wvps_ff",
                 io_signature::make(1, 1, sizeof(float) * ilen),
                 io_signature::make(1, 1, sizeof(float) * ceil_log2(ilen))),
      d_ilen(ilen),
      d_olen(ceil_log2(ilen))
{
}

// input vector assumed to be output from gsl wavelet computation

int wvps_ff_impl::work(int noutput_items,
                       gr_vector_const_void_star& input_items,
                       gr_vector_void_star& output_items)
{
    const float* in = (const float*)input_items[0];
    float* out = (float*)output_items[0];

    for (int count = 0; count < noutput_items; count++) {

        // any power?

        if (in[0] == 0.0) {
            for (int i = 0; i < d_olen; i++)
                out[i] = 0.0;

        } else {

            // get power normalization from 0-th wavelet coefficient

            float scl = 1.0 / (in[0] * in[0]);
            int k = 1;

            // sum powers over sequences of bins,
            // sequence lengths in increasing powers of 2

            for (int e = 0; e < d_olen; e++) {
                int m = 01 << e;
                float sum = 0.0;

                for (int l = 0; l < m; l++)
                    sum += (in[k + l] * in[k + l]);

                out[e] = scl * sum;
                k += m;
            }
        }

        in += d_ilen;
        out += d_olen;
    }

    return noutput_items;
}

} /* namespace wavelet */
} /* namespace gr */
