/* -*- c++ -*- */
/*
 * Copyright 2007,2008,2010-2012 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 "ofdm_sampler_impl.h"
#include <gnuradio/expj.h>
#include <gnuradio/io_signature.h>
#include <cstdio>

namespace gr {
namespace digital {

ofdm_sampler::sptr ofdm_sampler::make(unsigned int fft_length,
                                      unsigned int symbol_length,
                                      unsigned int timeout)
{
    return gnuradio::get_initial_sptr(
        new ofdm_sampler_impl(fft_length, symbol_length, timeout));
}

ofdm_sampler_impl::ofdm_sampler_impl(unsigned int fft_length,
                                     unsigned int symbol_length,
                                     unsigned int timeout)
    : block("ofdm_sampler",
            io_signature::make2(2, 2, sizeof(gr_complex), sizeof(char)),
            io_signature::make2(
                2, 2, sizeof(gr_complex) * fft_length, sizeof(char) * fft_length)),
      d_state(STATE_NO_SIG),
      d_timeout_max(timeout),
      d_fft_length(fft_length),
      d_symbol_length(symbol_length)
{
    GR_LOG_WARN(d_logger, "The gr::digital::ofdm_sampler block has been deprecated.");

    set_relative_rate(1, (uint64_t)fft_length); // buffer allocator hint
}

ofdm_sampler_impl::~ofdm_sampler_impl() {}

void ofdm_sampler_impl::forecast(int noutput_items, gr_vector_int& ninput_items_required)
{
    // FIXME do we need more
    // int nreqd  = (noutput_items-1) * d_symbol_length + d_fft_length;
    int nreqd = d_symbol_length + d_fft_length;
    unsigned ninputs = ninput_items_required.size();
    for (unsigned i = 0; i < ninputs; i++)
        ninput_items_required[i] = nreqd;
}

int ofdm_sampler_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* iptr = (const gr_complex*)input_items[0];
    const char* trigger = (const char*)input_items[1];

    gr_complex* optr = (gr_complex*)output_items[0];
    char* outsig = (char*)output_items[1];

    // FIXME: we only process a single OFDM symbol at a time; after the preamble, we can
    // process a few at a time as long as we always look out for the next preamble.

    unsigned int index = d_fft_length; // start one fft length into the input so we can
                                       // always look back this far

    outsig[0] = 0; // set output to no signal by default

    // Search for a preamble trigger signal during the next symbol length
    while ((d_state != STATE_PREAMBLE) && (index <= (d_symbol_length + d_fft_length))) {
        if (trigger[index]) {
            outsig[0] = 1; // tell the next block there is a preamble coming
            d_state = STATE_PREAMBLE;
        } else
            index++;
    }

    unsigned int i, pos, ret;
    switch (d_state) {
    case (STATE_PREAMBLE):
        // When we found a preamble trigger, get it and set the symbol boundary here
        for (i = (index - d_fft_length + 1); i <= index; i++) {
            *optr++ = iptr[i];
        }

        d_timeout = d_timeout_max; // tell the system to expect at least this many symbols
                                   // for a frame
        d_state = STATE_FRAME;
        consume_each(index - d_fft_length +
                     1); // consume up to one fft_length away to keep the history
        ret = 1;
        break;

    case (STATE_FRAME):
        // use this state when we have processed a preamble and are getting the rest of
        // the frames
        // FIXME: we could also have a power squelch system here to enter STATE_NO_SIG if
        // no power is received

        // skip over fft length history and cyclic prefix
        pos = d_symbol_length; // keeps track of where we are in the input buffer
        while (pos < d_symbol_length + d_fft_length) {
            *optr++ = iptr[pos++];
        }

        if (d_timeout-- == 0) {
            printf("TIMEOUT\n");
            d_state = STATE_NO_SIG;
        }

        consume_each(
            d_symbol_length); // jump up by 1 fft length and the cyclic prefix length
        ret = 1;
        break;

    case (STATE_NO_SIG):
    default:
        consume_each(index - d_fft_length); // consume everything we've gone through so
                                            // far leaving the fft length history
        ret = 0;
        break;
    }

    return ret;
}

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