ldpc.c File Reference

LDPC encoder and decoder. More...

#include <stdlib.h>
#include <math.h>
#include "jabcode.h"
#include "ldpc.h"
#include <string.h>
#include <stdio.h>
#include "detector.h"
#include "pseudo_random.h"

Functions
jab_int32 *	createMatrixA (jab_int32 wc, jab_int32 wr, jab_int32 capacity)
	Create matrix A for message data. More...
jab_int32	GaussJordan (jab_int32 *matrixA, jab_int32 wc, jab_int32 wr, jab_int32 capacity, jab_int32 *matrix_rank, jab_boolean encode)
	Gauss Jordan elimination algorithm. More...
jab_int32 *	createMetadataMatrixA (jab_int32 wc, jab_int32 capacity)
	Create the error correction matrix for the metadata. More...
jab_int32 *	createGeneratorMatrix (jab_int32 *matrixA, jab_int32 capacity, jab_int32 Pn)
	Create the generator matrix to encode messages. More...
jab_data *	encodeLDPC (jab_data *data, jab_int32 *coderate_params)
	LDPC encoding. More...
jab_int32	decodeMessage (jab_byte *data, jab_int32 *matrix, jab_int32 length, jab_int32 height, jab_int32 max_iter, jab_boolean *is_correct, jab_int32 start_pos)
	Iterative hard decision error correction decoder. More...
jab_int32	decodeLDPChd (jab_byte *data, jab_int32 length, jab_int32 wc, jab_int32 wr)
	LDPC decoding to perform hard decision. More...
jab_int32	decodeMessageILL (jab_float *enc, jab_int32 *matrix, jab_int32 length, jab_int32 checkbits, jab_int32 height, jab_int32 max_iter, jab_boolean *is_correct, jab_int32 start_pos, jab_byte *dec)
	LDPC Iterative Log Likelihood decoding algorithm for binary codes. More...
jab_int32	decodeMessageBP (jab_float *enc, jab_int32 *matrix, jab_int32 length, jab_int32 checkbits, jab_int32 height, jab_int32 max_iter, jab_boolean *is_correct, jab_int32 start_pos, jab_byte *dec)
	LDPC Iterative belief propagation decoding algorithm for binary codes. More...
jab_int32	decodeLDPC (jab_float *enc, jab_int32 length, jab_int32 wc, jab_int32 wr, jab_byte *dec)
	LDPC decoding to performe soft decision. More...

Detailed Description

LDPC encoder and decoder.

libjabcode - JABCode Encoding/Decoding Library

Copyright 2016 by Fraunhofer SIT. All rights reserved. See LICENSE file for full terms of use and distribution.

Contact: Huajian Liu liu@s.nosp@m.it.f.nosp@m.raunh.nosp@m.ofer.nosp@m..de Waldemar Berchtold walde.nosp@m.mar..nosp@m.berch.nosp@m.told.nosp@m.@sit..nosp@m.frau.nosp@m.nhofe.nosp@m.r.de

Function Documentation

jab_int32* createGeneratorMatrix	(	jab_int32 *	matrixA,
		jab_int32	capacity,
		jab_int32	Pn
	)

Create the generator matrix to encode messages.

Parameters

matrixA	the error correction matrix
capacity	the number of columns of the matrix
Pn	the number of net message bits

Returns

the generator matrix | NULL if failed (out of memory)

jab_int32* createMatrixA	(	jab_int32	wc,
		jab_int32	wr,
		jab_int32	capacity
	)

Create matrix A for message data.

Parameters

wc	the number of '1's in a column
wr	the number of '1's in a row
capacity	the number of columns of the matrix

Returns

the matrix A | NULL if failed (out of memory)

jab_int32* createMetadataMatrixA	(	jab_int32	wc,
		jab_int32	capacity
	)

Create the error correction matrix for the metadata.

Parameters

wc	the number of '1's in a column
capacity	the number of columns of the matrix

Returns

the error correction matrix | NULL if failed

jab_int32 decodeLDPC	(	jab_float *	enc,
		jab_int32	length,
		jab_int32	wc,
		jab_int32	wr,
		jab_byte *	dec
	)

LDPC decoding to performe soft decision.

Parameters

enc	the probability value for each bit position
length	the encoded data length
wc	the number of '1's in each column
wr	the number of '1's in each row
dec	the decoded data

Returns

the decoded data length | 0: decoding error

jab_int32 decodeLDPChd	(	jab_byte *	data,
		jab_int32	length,
		jab_int32	wc,
		jab_int32	wr
	)

LDPC decoding to perform hard decision.

Parameters

data	the encoded data
length	the encoded data length
wc	the number of '1's in a column
wr	the number of '1's in a row

Returns

the decoded data length | 0: fatal error (out of memory)

jab_int32 decodeMessage	(	jab_byte *	data,
		jab_int32 *	matrix,
		jab_int32	length,
		jab_int32	height,
		jab_int32	max_iter,
		jab_boolean *	is_correct,
		jab_int32	start_pos
	)

Iterative hard decision error correction decoder.

Parameters

data	the received data
matrix	the parity check matrix
length	the encoded data length
height	the number of check bits
max_iter	the maximal number of iterations
is_correct	indicating if decodedMessage function could correct all errors
start_pos	indicating the position to start reading in data array

Returns

1: error correction succeeded | 0: fatal error (out of memory)

jab_int32 decodeMessageBP	(	jab_float *	enc,
		jab_int32 *	matrix,
		jab_int32	length,
		jab_int32	checkbits,
		jab_int32	height,
		jab_int32	max_iter,
		jab_boolean *	is_correct,
		jab_int32	start_pos,
		jab_byte *	dec
	)

LDPC Iterative belief propagation decoding algorithm for binary codes.

Parameters

enc	the received reliability value for each bit
matrix	the decoding matrixreliability value for each bit
length	the encoded data length
checkbits	the rank of the matrix
height	the number of check bits
max_iter	the maximal number of iterations
is_correct	indicating if decodedMessage function could correct all errors
start_pos	indicating the position to start reading in enc array
dec	is the tentative decision after each decoding iteration

Returns

1: error correction succeded | 0: decoding failed

jab_int32 decodeMessageILL	(	jab_float *	enc,
		jab_int32 *	matrix,
		jab_int32	length,
		jab_int32	checkbits,
		jab_int32	height,
		jab_int32	max_iter,
		jab_boolean *	is_correct,
		jab_int32	start_pos,
		jab_byte *	dec
	)

LDPC Iterative Log Likelihood decoding algorithm for binary codes.

Parameters

enc	the received reliability value for each bit
matrix	the error correction decoding matrix
length	the encoded data length
checkbits	the rank of the matrix
height	the number of check bits
max_iter	the maximal number of iterations
is_correct	indicating if decodedMessage function could correct all errors
start_pos	indicating the position to start reading in enc array
dec	is the tentative decision after each decoding iteration

Returns

1: success | 0: fatal error (out of memory)

jab_data* encodeLDPC	(	jab_data *	data,
		jab_int32 *	coderate_params
	)

LDPC encoding.

Parameters

data	the data to be encoded
coderate_params	the two code rate parameter wc and wr indicating how many '1' in a column (Wc) and how many '1' in a row of the parity check matrix

Returns

the encoded data | NULL if failed

jab_int32 GaussJordan	(	jab_int32 *	matrixA,
		jab_int32	wc,
		jab_int32	wr,
		jab_int32	capacity,
		jab_int32 *	matrix_rank,
		jab_boolean	encode
	)

Gauss Jordan elimination algorithm.

Parameters

matrixA	the matrix
wc	the number of '1's in a column
wr	the number of '1's in a row
capacity	the number of columns of the matrix
matrix_rank	the rank of the matrix
encode	specifies if function is called by the encoder or decoder

Returns

0: success | 1: fatal error (out of memory)