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49 lines
1.7 KiB
49 lines
1.7 KiB
/*
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* Copyright (C) 2010,2014 by Jonathan Naylor G4KLX
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#ifndef AMBEFEC_H
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#define AMBEFEC_H
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#include "Golay.h"
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/*
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* Forward error correction for AMBE codec frames.
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*
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* D-Star uses AMBE+2 (72-bit frames) with a Golay(23,12) FEC scheme applied
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* to the most significant bits of each frame. regenerate() attempts to repair
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* bit errors in the three Golay codewords that make up one AMBE frame, and
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* returns the number of errors that were corrected. count() returns the number
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* of uncorrectable errors without modifying the data.
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*/
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class CAMBEFEC {
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public:
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CAMBEFEC();
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~CAMBEFEC();
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// Attempts in-place error correction; returns number of errors corrected.
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unsigned int regenerate(unsigned char* bytes) const;
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// Counts bit errors without modifying the data.
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unsigned int count(const unsigned char* bytes) const;
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private:
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unsigned int regenerate(unsigned int& a, unsigned int& b, unsigned int& c) const;
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unsigned int count(unsigned int a, unsigned int b, unsigned int c) const;
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};
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#endif
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