/usr/include/itpp/comm/bch.h is in libitpp-dev 4.3.1-8.
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* \file
* \brief Definition of a BCH encoder/decoder class
* \author Pal Frenger, Steve Peters, Adam Piatyszek and Stephan Ludwig
*
* -------------------------------------------------------------------------
*
* Copyright (C) 1995-2010 (see AUTHORS file for a list of contributors)
*
* This file is part of IT++ - a C++ library of mathematical, signal
* processing, speech processing, and communications classes and functions.
*
* IT++ 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 of the License, or (at your option) any
* later version.
*
* IT++ 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 IT++. If not, see <http://www.gnu.org/licenses/>.
*
* -------------------------------------------------------------------------
*/
#ifndef BCH_H
#define BCH_H
#include <itpp/comm/galois.h>
#include <itpp/comm/channel_code.h>
#include <itpp/itexports.h>
namespace itpp
{
/*!
\addtogroup fec
*/
//---------------------- BCH --------------------------------------
/*!
\ingroup fec
\brief Class for binary, narrow-sense BCH codes.
The notation used is found in S. B. Wicker, "Error control systems for
digital communication and storage", Appendix E, Prentice-Hall, 1995.
Example:
\code BCH bch(31,21,2,ivec("3 5 5 1"))
\endcode
uses the generator polynomial
\f$g(x) = x^{10} + x^9 + x^8 + x^6 + x^5 + x^3 + 1\f$, and is capable of
correcting 2 errors with \a n = 31 and \a k = 21.
*/
class ITPP_EXPORT BCH : public Channel_Code
{
public:
/*!
* \brief Initialize a (n,k)-code that can correct t errors
*
* \note Do not call this constructor with e.g. BCH bch(31, 21, 2, "3 5 5 1")
* but with BCH bch(31, 21, 2, ivec("3 5 5 1")) instead. Otherwise the
* complier will complain.
*/
BCH(int in_n, int in_k, int in_t, const ivec &genpolynom, bool sys = false);
/*!
* \brief Initialize a (n,k)-code that can correct t errors
* \author Stephan Ludwig
*
* The generator polynomial is automatically generated from the (n, t)
* parameters of the BCH code. The constructor generates the generator
* polynomial (and determines k) according to the method described in:
*
* [Wic95] S. B. Wicker, "Error control systems for digital communication
* and storage", Prentice-Hall, 1995
*/
BCH(int in_n, int in_t, bool sys = false);
//! Destructor
virtual ~BCH() { }
//! Encode a bvec of indata
virtual void encode(const bvec &uncoded_bits, bvec &coded_bits);
//! Encode a bvec of indata
virtual bvec encode(const bvec &uncoded_bits);
/*!
* \brief Decode the BCH code bits. Return false if there has been any decoding failure.
*
* The \c coded_bits are block-wise decoded into \c decoded_message messages. If
* there has been any decoding failure, the function will return \c false.
* If this happened in the n-th block, then \c cw_isvalid(n) will be set
* to \c false (zero-indexed). In case of a systematic code the systematic bits will be
* extracted and presented in the corresponding block of \c decoded_message.
* This is better than just presenting zeros, which is done in case of a
* decoding failure of non-systematic codes.
*/
virtual bool decode(const bvec &coded_bits, bvec &decoded_message, bvec &cw_isvalid);
//! Decode a bvec of coded data. This function is kept for backward compatibility. Better use \code bool decode(const bvec &coded_bits, bvec &decoded_message, bvec &cw_isvalid) \endcode.
virtual void decode(const bvec &coded_bits, bvec &decoded_bits);
//! Decode a bvec of coded data. This function is kept for backward compatibility. Better use \code bool decode(const bvec &coded_bits, bvec &decoded_message, bvec &cw_isvalid)\endcode.
virtual bvec decode(const bvec &coded_bits);
// Soft-decision decoding is not implemented
virtual void decode(const vec &received_signal, bvec &output);
virtual bvec decode(const vec &received_signal);
//! Get the code rate
virtual double get_rate() const {
return static_cast<double>(k) / n;
}
//! Get cardinality of code k
virtual int get_k() const {
return k;
}
//! Dummy assignment operator - MSVC++ warning C4512
BCH & operator= (const BCH &) {
return *this;
}
private:
int n, k, t;
GFX g;
const bool systematic;
};
} // namespace itpp
#endif // #ifndef BCH_H
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