Crc.java

import java.util.Scanner;
class CRC
{
static String datastream;
static String generator = "10001000000100001";
public static void main(String args[])
{
Scanner sc = new Scanner(System.in);
System.out.println("---At the Sender---\n Enter data stream:");
String datastream = sc.nextLine();
int datalen = datastream.length();
int genlen = generator.length();
int data[] = new int[datalen + genlen - 1];
int codeword[] = new int[datalen + genlen - 1];
int div[] = new int[generator.length()];
for(int i=0;i<datastream.length();i++)
data[i] = Integer.parseInt(datastream.charAt(i)+"");
for(int i=0;i<generator.length();i++)
div[i] = Integer.parseInt(generator.charAt(i)+"");
codeword = calculateCrc(data,div,datalen);
System.out.println("The CRC(Final Codeword) code is:");
for(int i=0;i<datastream.length();i++)
codeword[i] = Integer.parseInt(datastream.charAt(i)+"");
for(int i=0;i<data.length;i++)
System.out.print(codeword[i]);
System.out.println("\n");
System.out.print("---At the Receiver---\n Enter Received codeword:");
datastream = sc.nextLine();
data = new int[datastream.length() + generator.length() - 1];
for(int i=0;i<datastream.length();i++)
data[i] = Integer.parseInt(datastream.charAt(i)+"");
codeword = calculateCrc(data,div,datalen);
boolean valid = true;
for(int i=0;i<codeword.length;i++)
if(codeword[i]==1)
{
valid = false;
break;
}
if(valid==true)
System.out.println("Data stream is valid. No error occurred");
else
System.out.println("Data stream is invalid. CRC error occurred");
sc.close();
}
Public static int[] calculateCRC(int[] divrem, int[] divisor, int len)
{
for(int i=0;i<len;i++)
{
if(divrem[i]==1)
for(int j=0;j<divisor.length;j++)
divrem[i+j]^=divisor[j];
}
return divrem;
}
}