/* -*- 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 "atsc_rs_decoder_impl.h"
#include "gnuradio/dtv/atsc_consts.h"
#include <gnuradio/io_signature.h>

namespace gr {
  namespace dtv {

    static const int rs_init_symsize =     8;
    static const int rs_init_gfpoly  = 0x11d;
    static const int rs_init_fcr     =     0;	// first consecutive root
    static const int rs_init_prim    =     1;	// primitive is 1 (alpha)
    static const int rs_init_nroots  =    20;

    static const int N = (1 << rs_init_symsize) - 1;	// 255
    static const int K = N - rs_init_nroots;		// 235

    static const int amount_of_pad = N - ATSC_MPEG_RS_ENCODED_LENGTH;	  // 48

    atsc_rs_decoder::sptr
    atsc_rs_decoder::make()
    {
      return gnuradio::get_initial_sptr
	(new atsc_rs_decoder_impl());
    }

    atsc_rs_decoder_impl::atsc_rs_decoder_impl()
      : gr::sync_block("dtv_atsc_rs_decoder",
                       io_signature::make(1, 1, sizeof(atsc_mpeg_packet_rs_encoded)),
                       io_signature::make(1, 1, sizeof(atsc_mpeg_packet_no_sync)))
    {
      d_rs = init_rs_char(rs_init_symsize, rs_init_gfpoly, rs_init_fcr, rs_init_prim, rs_init_nroots);
      assert (d_rs != 0);
      nerrors_corrrected_count = 0;
      bad_packet_count = 0;
      total_packets = 0;
    }

    int atsc_rs_decoder_impl::decode (atsc_mpeg_packet_no_sync &out, const atsc_mpeg_packet_rs_encoded &in)
    {
      unsigned char tmp[N];
      int ncorrections;

      assert((int)(amount_of_pad + sizeof(in.data)) == N);

      // add missing prefix zero padding to message
      memset(tmp, 0, amount_of_pad);
      memcpy(&tmp[amount_of_pad], in.data, sizeof(in.data));

      // correct message...
      ncorrections = decode_rs_char(d_rs, tmp, 0, 0);

      // copy corrected message to output, skipping prefix zero padding
      memcpy (out.data, &tmp[amount_of_pad], sizeof (out.data));

      return ncorrections;
    }

    atsc_rs_decoder_impl::~atsc_rs_decoder_impl()
    {
      if (d_rs)
        free_rs_char (d_rs);
      d_rs = 0;
    }

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

      for (int i = 0; i < noutput_items; i++) {
        assert(in[i].pli.regular_seg_p());
        out[i].pli = in[i].pli;			// copy pipeline info...

        int nerrors_corrrected = decode(out[i], in[i]);
        out[i].pli.set_transport_error(nerrors_corrrected == -1);
        if (nerrors_corrrected == -1)
          bad_packet_count++;
        else
          nerrors_corrrected_count += nerrors_corrrected;

	total_packets++;
        #if 0
        if (total_packets > 1000) {
          // FIXME: convert to logger
          std::cout << "Error rate: "
                    << (float)nerrors_corrrected_count/total_packets
                    << "\tPacket error rate: "
                    << (float)bad_packet_count/total_packets
                    << std::endl;

          nerrors_corrrected_count = 0;
          bad_packet_count = 0;
          total_packets = 0;
        }
        #endif
      }

      return noutput_items;
    }

  } /* namespace dtv */
} /* namespace gr */
