C Program to implement CRC

/* CRC */



#include<stdio.h>

#include<conio.h>



int d[7],div[4],r[7];

void dn(int dd[]);



void main()

{

 int i,f=0;

 long int a;

 clrscr();

 printf("-----SENDER'S SIDE-----\n\n");

 printf("Enter code : ");

 scanf("%ld",&a);

 for(i=3;i>-1;i--)

 {

  d[i] = (long)a%10;

  a=a/10;

 }

 d[4]=d[5]=d[6]=0;



 printf("Enter divisor: ");

 scanf("%ld",&a);

 for(i=3;i>-1;i--)

 {

  div[i] = a%10;

  a=a/10;

 }



 printf("\nData before processing: ");

 for(i=0;i<7;i++) printf("%d",d[i]);

 dn(d);

 printf("\nGenerated syndrome: %d%d%d\n\n",d[4],d[5],d[6]);



 printf("-----RECEIVER'S SIDE-----\n\n");

 printf("Enter data at Receiver: ");

 scanf("%ld",&a);

 for(i=6;i>-1;i--)

 {

  r[i] = a%10;

  a=a/10;

 }



 dn(r);

 for(i=4;i<7;i++) if(r[i]==1){f=1;break;}

 printf("Receiver's syndrome: ");

 for(i=4;i<7;i++) printf("%d",r[i]);



 if(f==1) printf("\n\nError in Transmission!!");

 else printf("\n\nNo Error in Transmission!!");

 getch();

}



void dn(int dd[])

{

 int i,j;

 for(i=0;i<4;i++)

 {

  if(dd[i]==0) continue;

  for(j=i+3;j>=i;j--)

  {

   dd[j] = dd[j]^div[j-i];

  }

 }

}





/* OUTPUT-1



-----SENDER'S SIDE-----



Enter code : 1001

Enter divisor: 1011



Data before processing: 1001000

Generated syndrome: 110



-----RECEIVER'S SIDE-----



Enter data at Receiver: 1001110

Receiver's syndrome: 000



No Error in Transmission!!

*/



/* OUTPUT-2



-----SENDER'S SIDE-----



Enter code : 1001

Enter divisor: 1011



Data before processing: 1001000

Generated syndrome: 110



-----RECEIVER'S SIDE-----



Enter data at Receiver: 1001111.

Receiver's syndrome: 001



Error in Transmission!!

*/