atsc_field_sync_mux.cc

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/* -*- 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_field_sync_mux.h>
#include <gr_io_signature.h>
#include <atsc_consts.h>
#include <atsci_pnXXX.h>


atsc_field_sync_mux_sptr
atsc_make_field_sync_mux()
{
  return atsc_field_sync_mux_sptr(new atsc_field_sync_mux());
}

atsc_field_sync_mux::atsc_field_sync_mux()
  : gr_sync_block("atsc_field_sync_mux",
		  gr_make_io_signature(1, 1, sizeof(atsc_data_segment)),
		  gr_make_io_signature(1, 1, sizeof(atsc_data_segment)))
{
  reset();
}

static const int NUMBER_OF_OUTPUTS = 1; // # of output streams (almost always one)

static const int N_SAVED_SYMBOLS = atsc_field_sync_mux::N_SAVED_SYMBOLS;

static void
init_field_sync_common (unsigned char *p, int mask,
                        const unsigned char saved_symbols[N_SAVED_SYMBOLS])
{
  static const unsigned char bin_map[2] = { 1, 6 };  // map binary values to 1 of 8 levels

  int  i = 0;

  p[i++] = bin_map[1];                  // data segment sync pulse
  p[i++] = bin_map[0];
  p[i++] = bin_map[0];
  p[i++] = bin_map[1];

  for (int j = 0; j < 511; j++)         // PN511
    p[i++] = bin_map[atsc_pn511[j]];

  for (int j = 0; j < 63; j++)          // PN63
    p[i++] = bin_map[atsc_pn63[j]];

  for (int j = 0; j < 63; j++)          // PN63, toggled on field 2
    p[i++] = bin_map[atsc_pn63[j] ^ mask];

  for (int j = 0; j < 63; j++)          // PN63
    p[i++] = bin_map[atsc_pn63[j]];

  p[i++] = bin_map[0];                  // 24 bits of VSB8 mode identifiera
  p[i++] = bin_map[0];
  p[i++] = bin_map[0];
  p[i++] = bin_map[0];

  p[i++] = bin_map[1];
  p[i++] = bin_map[0];
  p[i++] = bin_map[1];
  p[i++] = bin_map[0];

  p[i++] = bin_map[0];
  p[i++] = bin_map[1];
  p[i++] = bin_map[0];
  p[i++] = bin_map[1];

  p[i++] = bin_map[1];
  p[i++] = bin_map[1];
  p[i++] = bin_map[1];
  p[i++] = bin_map[1];

  p[i++] = bin_map[0];
  p[i++] = bin_map[1];
  p[i++] = bin_map[0];
  p[i++] = bin_map[1];

  p[i++] = bin_map[1];
  p[i++] = bin_map[0];
  p[i++] = bin_map[1];
  p[i++] = bin_map[0];


  for (int j = 0; j < 92; j++)          // 92 more bits
    p[i++] = bin_map[atsc_pn63[j % 63]];

  // now copy the last 12 symbols of the previous segment

  for (int j = 0; j < N_SAVED_SYMBOLS; j++)
    p[i++] = saved_symbols[j];

  assert (i == ATSC_DATA_SEGMENT_LENGTH);
}
inline static void
init_field_sync_1 (atsc_data_segment *s,
                   const unsigned char saved_symbols[N_SAVED_SYMBOLS])
{
  init_field_sync_common (&s->data[0], 0, saved_symbols);
}

inline static void
init_field_sync_2 (atsc_data_segment *s,
                   const unsigned char saved_symbols[N_SAVED_SYMBOLS])

{
  init_field_sync_common (&s->data[0], 1, saved_symbols);
}

static void
save_last_symbols (unsigned char saved_symbols[N_SAVED_SYMBOLS],
                   const atsc_data_segment &seg)
{
  for (int i = 0; i < N_SAVED_SYMBOLS; i++)
    saved_symbols[i] = seg.data[i + ATSC_DATA_SEGMENT_LENGTH - N_SAVED_SYMBOLS];}


inline static bool
last_regular_seg_p (const plinfo &pli)
{
  return pli.regular_seg_p () && (pli.segno () == ATSC_DSEGS_PER_FIELD - 1);
}

void
atsc_field_sync_mux::forecast (int noutput_items, gr_vector_int &ninput_items_required)
{
  unsigned ninputs = ninput_items_required.size();
  for (unsigned i = 0; i < ninputs; i++) 
    ninput_items_required[i] = fixed_rate_noutput_to_ninput (noutput_items);
  
}


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

  unsigned int index = 0;
  for (unsigned int outdex = 0; outdex < noutput_items; outdex++){

    assert (in[index].pli.regular_seg_p ());

    if (!in[index].pli.first_regular_seg_p ()){
      out[outdex] = in[index];                  // just copy in to out

      if (last_regular_seg_p (in[index].pli))
        save_last_symbols (d_saved_symbols, in[index]);

      index++;
    }
    else {                                      // first_regular_seg_p
      if (!d_already_output_field_sync){
        // write out field sync...
        atsc_data_segment       field_sync;

        if (in[index].pli.in_field1_p ())
          init_field_sync_1 (&field_sync, d_saved_symbols);
        else
          init_field_sync_2 (&field_sync, d_saved_symbols);

        // note that index doesn't advance in this branch
        out[outdex] = field_sync;
        d_already_output_field_sync = true;
      }
      else {
        // already output field sync, now output first regular segment
        out[outdex] = in[index];
        index++;
        d_already_output_field_sync = false;
      }
    }
  }

  d_current_index += index;

  return noutput_items;
}