GNU Radio 3.5.1 C++ API
atsci_basic_trellis_encoder.h
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00001 /* -*- c++ -*- */
00002 /*
00003  * Copyright 2002 Free Software Foundation, Inc.
00004  * 
00005  * This file is part of GNU Radio
00006  * 
00007  * GNU Radio is free software; you can redistribute it and/or modify
00008  * it under the terms of the GNU General Public License as published by
00009  * the Free Software Foundation; either version 3, or (at your option)
00010  * any later version.
00011  * 
00012  * GNU Radio is distributed in the hope that it will be useful,
00013  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00014  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00015  * GNU General Public License for more details.
00016  * 
00017  * You should have received a copy of the GNU General Public License
00018  * along with GNU Radio; see the file COPYING.  If not, write to
00019  * the Free Software Foundation, Inc., 51 Franklin Street,
00020  * Boston, MA 02110-1301, USA.
00021  */
00022 #ifndef _ATSC_BASIC_TRELLIS_ENCODER_H_
00023 #define _ATSC_BASIC_TRELLIS_ENCODER_H_
00024 
00025 #include <atsc_api.h>
00026 #include <assert.h>
00027 
00028 /*!
00029  * \brief ATSC trellis encoder building block.
00030  *
00031  * Note this is NOT the 12x interleaved interface.
00032  *
00033  * This implements a single instance of the ATSC trellis encoder.
00034  * This is a rate 2/3 encoder (really a constraint length 3, rate 1/2
00035  * encoder with the top bit passed through unencoded.  This does not
00036  * implement the "precoding" of the top bit, because the NTSC rejection
00037  * filter is not supported.
00038  */
00039 
00040 class ATSC_API atsci_basic_trellis_encoder {
00041 
00042 private:
00043   int               state;              // two bit state;
00044 
00045 public:
00046   atsci_basic_trellis_encoder () : state (0) {}
00047 
00048   /*!
00049    * Encode two bit INPUT into 3 bit return value.  Domain is [0,3],
00050    * Range is [0,7].  The mapping to bipolar levels is not done.
00051    */
00052   int encode (unsigned int input);
00053 
00054   //! reset encoder state
00055   void reset () { state = 0; }
00056 
00057   static const unsigned char next_state[32];
00058   static const unsigned char out_symbol[32];
00059 };
00060 
00061 #endif /* _ATSC_BASIC_TRELLIS_ENCODER_H_ */