atsc_randomizer.cc

这是用python语言写的一个数字广播的信号处理工具包。利用它

/* -*- c++ -*- */
/*
 * Copyright 2006 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_randomizer.h>
#include <gr_io_signature.h>
#include <atsc_consts.h>


atsc_randomizer_sptr
atsc_make_randomizer()
{
  return atsc_randomizer_sptr(new atsc_randomizer());
}

atsc_randomizer::atsc_randomizer()
  : gr_sync_block("atsc_randomizer",
		  gr_make_io_signature(1, 1, sizeof(atsc_mpeg_packet)),
		  gr_make_io_signature(1, 1, sizeof(atsc_mpeg_packet_no_sync)))
{
  reset();
}

void
atsc_randomizer::reset()
{
  d_rand.reset();
  d_field2 = false;
  d_segno = 0;
}

int
atsc_randomizer::work (int noutput_items,
		       gr_vector_const_void_star &input_items,
		       gr_vector_void_star &output_items)
{
  const atsc_mpeg_packet *in = (const atsc_mpeg_packet *) 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++){

    // sanity check incoming data.
    assert((in[i].data[0] == MPEG_SYNC_BYTE));
    assert((in[i].data[1] & MPEG_TRANSPORT_ERROR_BIT) == 0);

    // initialize plinfo for downstream
    //
    // We do this here because the randomizer is effectively
    // the head of the tx processing chain
    //
    out[i].pli.set_regular_seg(d_field2, d_segno);
    d_segno++;
    if (d_segno == 312){
      d_segno = 0;
      d_field2 = !d_field2;
    }

    if (out[i].pli.first_regular_seg_p())
      d_rand.reset();

    d_rand.randomize(out[i], in[i]);
  }

  return noutput_items;
}