Package com.google.zxing.pdf417.decoder.ec

Class ErrorCorrection

java.lang.Object

com.google.zxing.pdf417.decoder.ec.ErrorCorrection

public final class ErrorCorrection
extends java.lang.Object

PDF417 error correction implementation.

This example is quite useful in understanding the algorithm.

See Also:

ReedSolomonDecoder

Field Summary

Fields

Modifier and Type	Field	Description
private ModulusGF	field

Constructor Summary

Constructors

Constructor	Description
ErrorCorrection()

Method Summary

Modifier and Type	Method	Description
int	decode(int[] received, int numECCodewords, int[] erasures)
private int[]	findErrorLocations(ModulusPoly errorLocator)
private int[]	findErrorMagnitudes(ModulusPoly errorEvaluator, ModulusPoly errorLocator, int[] errorLocations)
private ModulusPoly[]	runEuclideanAlgorithm(ModulusPoly a, ModulusPoly b, int R)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

field

private final ModulusGF field

Constructor Detail

ErrorCorrection

public ErrorCorrection()

Method Detail

decode

public int decode(int[] received,
                  int numECCodewords,
                  int[] erasures)
           throws ChecksumException

Parameters:

received - received codewords

numECCodewords - number of those codewords used for EC

erasures - location of erasures

Returns:

number of errors

Throws:

ChecksumException - if errors cannot be corrected, maybe because of too many errors

runEuclideanAlgorithm

private ModulusPoly[] runEuclideanAlgorithm(ModulusPoly a,
                                            ModulusPoly b,
                                            int R)
                                     throws ChecksumException

Throws:

ChecksumException

findErrorLocations

private int[] findErrorLocations(ModulusPoly errorLocator)
                          throws ChecksumException

Throws:

ChecksumException

findErrorMagnitudes

private int[] findErrorMagnitudes(ModulusPoly errorEvaluator,
                                  ModulusPoly errorLocator,
                                  int[] errorLocations)