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

import java.io.*;

import java.util.*;

public class CRC

 {

 public static void main(String args[])

{

Scanner s=new Scanner(System.in);

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

int  n=s.nextInt();

int data[ ]=new int[n];

System.out.println("Enter the data bits : ");

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

data[i]=s.nextInt();

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

int m=s.nextInt();

int divisor[ ]=new int[m];

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

for(int j=0;j<m;j++)

divisor[j]=s.nextInt();

int len=n+m-1;

int div[ ]=new int[len];

int rem[ ]=new int[len];

int crc[ ]=new int[len];

int src[ ]=new int[len];

for(int i=0;i<data.length;i++)

div[i]=data[i];

System.out.println("Dividend after appending zero");

for(int i=0;i<div.length;i++)

System.out.print(div[i]);

System.out.println();

for(int j=0;j<div.length;j++)

rem[j]=div[j];

rem=divide(div,divisor,rem);

for(int i=0;i<div.length;i++)

crc[i]=(div[i]^rem[i]);

System.out.println();

System.out.println("crc code");

for(int i=0;i<crc.length;i++)

System.out.print(crc[i]);

System.out.println();

System.out.println("crc code of"+len+"bits");

System.out.println("enter crc code");

for(int i=0;i<div.length;i++)

crc[i]=s.nextInt();

for(int i=0;i<src.length;i++)

for(int j=0;j<crc.length;j++)

rem[j]=crc[j];

rem=divide(crc,divisor,rem);

for(int i=0;i<rem.length;i++)

{

if(rem[i]!=0)

{

System.out.println("error!!!");

break;

}

if(i==rem.length-1)

System.out.println("no error");

}

}

static int[ ] divide (int div[ ],int divisor[ ],int rem[ ])

{

int cur=0;

while(true)

{

for(int i=0;i<divisor.length;i++)

rem[cur+i]=(rem[cur+i]^divisor[i]);

while(rem[cur]==0 && cur!=rem.length-1)

cur++;

if((rem.length-cur)<divisor.length)

break;

}

return rem;

}

}