79. JAVA PROGRAM FOR CYCLIC REDUNDANCY CHECK

//CYCLIC REDUNDANCY CHECK

import java.io.*;

import java.lang.*;

public class crc

{

public static void main(String args[]) throws IOException

{

int f[]=new int[25];

int gen[]=new int[10];

int rem[]=new int[10];

int flen,glen,rlen,i,j;

int p,sum,iframe,igen,irem;

String data;

BufferedReader in=new BufferedReader(new InputStreamReader(System.in));

System.out.println("Enter the frame:");

data=in.readLine();flen=data.length()-1;

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

f[i]=(int)(data.charAt(i))-48;

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

data=in.readLine();

glen=data.length()-1;

for(i=1;i<=glen;i++)

f[flen+i]=0;

flen=flen+glen;

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

gen[i]=((int)(data.charAt(i))-48);

p=0;

sum=0;

for(i=flen;i>=0;i--)

{

sum=sum+(f[i]*(int)Math.pow(2,p));

p=p+1;

}

iframe=sum;

p=0;

sum=0;

for(i=glen;i>=0;i--)

{

sum=sum+(gen[i]*(int)Math.pow(2,p));

p=p+1;

}

igen=sum;

irem=iframe%igen;

irem=igen-irem;

i=0;

while(iframe>0)

{

f[i]=iframe%2;

iframe=iframe/2;i++;

}

if(iframe == 1)

f[i]=iframe;

System.out.print("Transmitted string:");

for(i=flen;i>=0;i--)

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

System.out.print("\n\nEnter the received string:");

data=in.readLine();

flen=data.length()-1;

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

f[i]=((int)(data.charAt(i)))-48;

p=0;

sum=0;

for(i=flen;i>=0;i--)

{

 p=p+1;

}

iframe=sum;

irem=iframe%igen;

if(irem==0)

{

System.out.println("Message received with no error");

}

else

{

System.out.println("Message received with error");

}

}

}

OUTPUT:

Enter the frame: 10101011

Enter the generator: 1011

Transmitted string:10101011000

Enter the received string:1011

Message received with no error