/* -*- c++ -*- */
/*
 * Copyright 2015 Free Software Foundation, Inc.
 *
 * This 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.
 *
 * This software 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 this software; 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_encoder_impl.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_encoder::sptr atsc_rs_encoder::make()
{
    return gnuradio::get_initial_sptr(new atsc_rs_encoder_impl());
}

atsc_rs_encoder_impl::atsc_rs_encoder_impl()
    : gr::sync_block("atsc_rs_encoder",
                     gr::io_signature::make(1, 1, sizeof(atsc_mpeg_packet_no_sync)),
                     gr::io_signature::make(1, 1, sizeof(atsc_mpeg_packet_rs_encoded)))
{
    d_rs = init_rs_char(
        rs_init_symsize, rs_init_gfpoly, rs_init_fcr, rs_init_prim, rs_init_nroots);
    assert(d_rs != 0);
}

atsc_rs_encoder_impl::~atsc_rs_encoder_impl()
{
    if (d_rs) {
        free_rs_char(d_rs);
    }

    d_rs = 0;
}

void atsc_rs_encoder_impl::encode(atsc_mpeg_packet_rs_encoded& out,
                                  const atsc_mpeg_packet_no_sync& in)
{
    unsigned char tmp[K];

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

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

    // copy message portion to output packet
    memcpy(out.data, in.data, sizeof(in.data));

    // now compute parity bytes and add them to tail end of output packet
    encode_rs_char(d_rs, tmp, &out.data[sizeof(in.data)]);
}

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

    // Tell runtime system how many output items we produced.
    return noutput_items;
}

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