Reed-Solomon Codes. More...

#include <itpp/comm/reedsolomon.h>

Inheritance diagram for itpp::Reed_Solomon:

Public Member Functions
	Reed_Solomon (int in_m, int in_t, bool sys=false, int in_b=1)

virtual	~Reed_Solomon ()
	Destructor.

virtual void	encode (const bvec &uncoded_bits, bvec &coded_bits)
	Encoder function.

virtual bvec	encode (const bvec &uncoded_bits)
	Encoder function.

virtual bool	decode (const bvec &coded_bits, const ivec &erasure_positions, bvec &decoded_message, bvec &cw_isvalid)
	Decode the RS code bits. Return false if there has been any decoding failure.

virtual bool	decode (const bvec &coded_bits, bvec &decoded_message, bvec &cw_isvalid)
	Decode the RS code bits. Return false if there has been any decoding failure.

virtual void	decode (const bvec &coded_bits, bvec &decoded_bits)
	Decoder a `bvec` of coded data. This function is kept for backward compatibility. Better use.

virtual bvec	decode (const bvec &coded_bits)
	Decoder a `bvec` of coded data. This function is kept for backward compatibility. Better use.

virtual void	decode (const vec &received_signal, bvec &output)
	Decode a vec of received data.

virtual bvec	decode (const vec &received_signal)
	Decode a vec of received data.

virtual double	get_rate () const
	Gets the rate of the RS-code.

Reed_Solomon &	operator= (const Reed_Solomon &)
	Dummy assignment operator - MSVC++ warning C4512.

Protected Attributes
GFX	g
	The generator polynomial of the RS code.

const bool	systematic
	Whether or not the code is systematic.


int	m

int	t

int	k

int	n

int	q

int	b

Detailed Description

Reed-Solomon Codes.

Uses the Berlkamp-Massey algorithm for decoding as described in: S. B. Wicker, "Error Control Systems for digital communication and storage," Prentice Hall.

The code is $2^m$ - ary of length $2^m-1$ capable of correcting $t$ errors.

Definition at line 51 of file reedsolomon.h.

Constructor & Destructor Documentation

itpp::Reed_Solomon::Reed_Solomon	(	int	in_m,
		int	in_t,
		bool	sys = `false`,
		int	in_b = `1`
	)

Class constructor for the $2^m$ - ary, $t$ error correcting RS-code. The generator polynomial will be $g(x)={i=0}^{2t-1}(x-^{b+i})$, where $$ is a root of the primitive polynomial of itpp::GF.

Definition at line 55 of file reedsolomon.cpp.

References b, g, it_assert, k, m, n, itpp::pow2i(), q, itpp::GFX::set(), and t.

Member Function Documentation

bool itpp::Reed_Solomon::decode	(	const bvec &	coded_bits,
		const ivec &	erasure_positions,
		bvec &	decoded_message,
		bvec &	cw_isvalid
	)

virtual

Decode the RS code bits. Return false if there has been any decoding failure.

The coded_bits are block-wise decoded into decoded_message messages. If there has been any decoding failure, the function will return false. If this happened in the n-th block, then cw_isvalid(n) will be set to false (zero-indexed). In case of a systematic code the systematic bits will be extracted and presented in the corresponding block of decoded_message. This is better than just presenting zeros, which is done in case of a decoding failure of non-systematic codes.

For erasure decoding the indices of erased positions need to be passed in erasure_positions as indices to the erased (not bit!).

Definition at line 121 of file reedsolomon.cpp.

References b, itpp::concat(), itpp::divgfx(), itpp::floor_i(), itpp::formal_derivate(), g, it_assert, k, m, itpp::max(), n, itpp::ones_i(), q, itpp::GFX::set_degree(), systematic, t, and itpp::zeros_b().

Referenced by decode().

bool itpp::Reed_Solomon::decode	(	const bvec &	coded_bits,
		bvec &	decoded_message,
		bvec &	cw_isvalid
	)

virtual

Decode the RS code bits. Return false if there has been any decoding failure.

The coded_bits are block-wise decoded into decoded_message messages. If there has been any decoding failure, the function will return false. If this happened in the n-th block, then cw_isvalid(n) will be set to false (zero-indexed). In case of a systematic code the systematic bits will be extracted and presented in the corresponding block of decoded_message. This is better than just presenting zeros, which is done in case of a decoding failure of non-systematic codes.

Definition at line 278 of file reedsolomon.cpp.

References decode().