ComputerNetworksLab/crc.java at master · Pythonista7/ComputerNetworksLab · GitHub

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importjava.util.*;

classcrc
{


publicstaticvoidmain(Stringargs[])
	{
Scanners=newScanner(System.in);

intk,g;
System.out.println("Enter degree of data :");
k=s.nextInt();
System.out.println("Enter degree of generator :");
g=s.nextInt();

intdata[] = newint [200];
intgen[] = newint [200];

//function to input
System.out.println("Enter data: ");//113659.20
data=input(data,k);
System.out.println("Enter generator: ");
gen=input(gen,g);

//Pad the input with zeros
intcodeword[] = newint[200];

for(inti=k;i<k+g-1;i++)
data[i]=0;

/*Disp after padding
 System.out.println("Padded Codeword");
 for(int i=0;i<k+g-1;i++)
 System.out.println(codeword[i]);
 */

//Division part
//codeword=data because data was padded with zeros and stored in codeword
codeword=div(data,gen,k,g);
System.out.println("Checksum is :");
for(inti=k;i<k+g-1;i++)
 {
data[i]=codeword[i];
System.out.println(data[i]);
 }

System.out.println("Codeword is :");
for(inti=0;i<k+g-1;i++)
 {
System.out.println(data[i]);
 }

intcodewordR[]=newint[200];
intdataR[]=newint[200];
System.out.println("RE-ENTER CODEWORD for reciever :");
//get user input for codewordR
dataR=input(codewordR,k+g-1);

//divide new codeword with gen
codewordR=div(dataR,gen,k,g);
intflag=0;
//System.out.println("After Division");
for(inti=k;i<k+g-1;i++)
 {	if(codewordR[i]!=0)
 {	flag=1;
break;
 }
else
flag=0;
//System.out.println(codewordR[i]);
 }
if(flag==1)
System.out.println("ERROR");

else
System.out.println("NO ERROR");
	}

//Input helper function
publicstaticint[] input(intarr[],intl)
	{	Scanners =newScanner(System.in);
for(inti=0;i<l;i++)
arr[i]=s.nextInt();
returnarr;
	}

//Division Helper function,function recieves parameter k as n.
publicstaticint[] div(intdata[],intgen[],intn,intg)
	{
intk,msb;
intr[]=newint[200];

for(inti=0;i<g;i++)
 {
r[i]=data[i];
 }

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

msb=r[i];
for(intj=i;j<g+i;j++)
 {
if(msb==0)
r[j]=r[j]^0;
else
r[j]=r[j]^gen[k];

k++;

 }


r[g+i]=data[g+i];
 }


returnr;


	}


}