CN 7 - CRC

7. Write a program for error detecting code using CRC-CCITT (16- bits).

Crc.java - PROGRAM

import java.util.Scanner;

public class Crc {

static int n,m,msb,i,j,k,g[],d[],z[],r[];

public static void main(String[] args) 

{

Scanner s=new Scanner(System.in);

System.out.println("Enter no. of databits:");

n=s.nextInt();

System.out.println("Enter no. of generator bits:");

m=s.nextInt();

d=new int[m+n];

g=new int[n];

System.out.println("Enter databits:");

for(i=0;i<n;i++)

d[i]=s.nextInt();

System.out.println("Enter generator bits:");

for(i=0;i<m;i++)

g[i]=s.nextInt();

crcEval();

System.out.println("\nThe code data is:");

for(i=0;i<n+m-1;i++)

System.out.println(d[i]);

crcEval();

boolean t=true;

for(i=n;i<n+m-1;i++) {

if(r[i]==1)

t=false;

}

if(t)

System.out.println("\nNo error");

else

System.out.println("Error");

}

private static void crcEval() 

{

r=new int[m+n];

for(i=0;i<m;i++)

r[i]=d[i];

z=new int[m];

for(i=0;i<n;i++) {

k=0;

msb=r[i];

for(j=i;j<m+i;j++) {

if(msb==0)

r[j]=r[j]^z[k];

else

r[j]=r[j]^g[k];

k++;

}

r[m+i]=d[m+i];

}

//System.out.println("The code bits added are:");

for(i=n;i<n+m-1;i++) {

d[i]=r[i];

//System.out.print(d[i]+" ");

}

}

}

OUTPUT :

( click on image to zoom )