atsci_basic_trellis_encoder.h

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/* -*- c++ -*- */
/*
 * Copyright 2002 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.
 */
#ifndef _ATSC_BASIC_TRELLIS_ENCODER_H_
#define _ATSC_BASIC_TRELLIS_ENCODER_H_

#include <assert.h>

/*!
 * \brief ATSC trellis encoder building block.
 *
 * Note this is NOT the 12x interleaved interface.
 *
 * This implements a single instance of the ATSC trellis encoder.
 * This is a rate 2/3 encoder (really a constraint length 3, rate 1/2
 * encoder with the top bit passed through unencoded.  This does not
 * implement the "precoding" of the top bit, because the NTSC rejection
 * filter is not supported.
 */

class atsci_basic_trellis_encoder {

private:
  int               state;              // two bit state;

public:
  atsci_basic_trellis_encoder () : state (0) {}

  /*!
   * Encode two bit INPUT into 3 bit return value.  Domain is [0,3],
   * Range is [0,7].  The mapping to bipolar levels is not done.
   */
  int encode (unsigned int input);

  //! reset encoder state
  void reset () { state = 0; }

  static const unsigned char next_state[32];
  static const unsigned char out_symbol[32];
};

#endif /* _ATSC_BASIC_TRELLIS_ENCODER_H_ */