/* -*- c++ -*- */

/*

 * Copyright 2008 Free Software Foundation, Inc.

 * 

 * 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 INCLUDED_GR_DECODE_CCSDS_27_FB_H

#define INCLUDED_GR_DECODE_CCSDS_27_FB_H

#include <gr_sync_decimator.h>

extern "C" {

#include "../viterbi/viterbi.h"

}

class gr_decode_ccsds_27_fb;

typedef boost::shared_ptr<gr_decode_ccsds_27_fb> gr_decode_ccsds_27_fb_sptr;

gr_decode_ccsds_27_fb_sptr gr_make_decode_ccsds_27_fb();

/*! \brief A rate 1/2, k=7 convolutional decoder for the CCSDS standard

 * \ingroup ecc

 *  

 * This block performs soft-decision convolutional decoding using the Viterbi

 * algorithm.

 *  

 * The input is a stream of (possibly noise corrupted) floating point values 

 * nominally spanning [-1.0, 1.0], representing the encoded channel symbols 

 * 0 (-1.0) and 1 (1.0), with erased symbols at 0.0.

 *

 * The output is MSB first packed bytes of decoded values.

 *

 * As a rate 1/2 code, there will be one output byte for every 16 input symbols.

 *

 * This block is designed for continuous data streaming, not packetized data.

 * The first 32 bits out will be zeroes, with the output delayed four bytes

 * from the corresponding inputs.

 */

class gr_decode_ccsds_27_fb : public gr_sync_decimator

{

private:

  friend gr_decode_ccsds_27_fb_sptr gr_make_decode_ccsds_27_fb();

  gr_decode_ccsds_27_fb();

  // Viterbi state

  int d_mettab[2][256];

  struct viterbi_state d_state0[64];

  struct viterbi_state d_state1[64];

  unsigned char d_viterbi_in[16];

  int d_count;

public:

  ~gr_decode_ccsds_27_fb();

  int work (int noutput_items,

            gr_vector_const_void_star &input_items,

            gr_vector_void_star &output_items);

};

#endif /* INCLUDED_GR_DECODE_CCSDS_27_FB_H */