at.ac.fhstp.sonitalk.utils

Class CRC

java.lang.Object

at.ac.fhstp.sonitalk.utils.CRC

public class CRC
extends java.lang.Object

The CRC class adds and also checks the parity bits. The main part of both functions is a xor_logic_gate. Beside that it has a helper function for counting occurrences.

Constructor Summary

Constructors

Constructor and Description
CRC()
CRC(byte[] generatorPolynom)

Method Summary

Modifier and Type	Method and Description
int	checkMessageCRC(int[] messageDecoded) Checks if a message was received correctly.
static int	countOccurrences(java.lang.String input, char searchedChar) Returns the number of occurrences of searchedChar in input.
java.lang.String	parityBit(java.lang.String bitOfText) Calls xorArray to get a remainder bit sequence depending on the generator polynomal.

Methods inherited from class java.lang.Object

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

Constructor Detail

CRC

public CRC()

CRC

public CRC(byte[] generatorPolynom)

Method Detail

checkMessageCRC

public int checkMessageCRC(int[] messageDecoded)

Checks if a message was received correctly. Returns 0 if the CRC is correct.

Parameters:

messageDecoded - bit sequence containing the message to be checked

Returns:

0 if the CRC is correct otherwise a positive integer

parityBit

public java.lang.String parityBit(java.lang.String bitOfText)

Calls xorArray to get a remainder bit sequence depending on the generator polynomal. returns this bit sequence as error detection for the message

Parameters:

bitOfText - the message after which the error detection bit sequence is generated

Returns:

error detection bit sequence

countOccurrences

public static int countOccurrences(java.lang.String input,
                                   char searchedChar)

Returns the number of occurrences of searchedChar in input. Source : https://stackoverflow.com/a/275969/5232306

Parameters:

input -

searchedChar -

Returns:

How many occurrences of searchedChar are in input.