Cyclic Redundancy Check program in C | CRC

Write a program to compute CRC code for the polynomials CRC-12, CRC-16 and CRC CCIP

 Name of Experiment: Cyclic Redundancy Check

Hardware Requirements: Intel based Desktop PC:RAM of 1GB

Software Requirement: Turbo C / Turbo C++

Theory:

Cyclic Redundancy Checks fall into the same category as parity bits, check digits, and checksums: Their use is to detect transmission errors. Depending on the error model assumed (i.e., what types of transmission errors are to be expected, which typically depends on the transmission media), different forms of checking are appropriate.

This technique involves binary division of the data bits being sent. The divisor is generated using polynomials. The sender performs a division operation on the bits being sent and calculates the remainder. Before sending the actual bits, the sender adds the remainder at the end of the actual bits. Actual data bits plus the remainder is called a codeword. The sender transmits data bits as code-words. At the other end, the receiver performs division operation on code-words using the same CRC divisor. If the remainder contains all zeros the data bits are accepted, otherwise it is considered as there some data corruption occurred in transit.

SOURCE CODE:

// Program for Cyclic Redundancy Check

 #include<stdio.h>

int gen[4],genl, frl, rem[4];

void main ( )

{

            int i,j,fr[8],dupfr[11],recfr[11],tlen,flag;

            frl=8;  genl=4;

            printf ("Enter frame:\n");

            for (i=0; i<frl; i++)

            {

            scanf ("%d", &fr[i]);

            dupfr[i]=fr[i];

            }

            printf("Enter generator:\n");

            for (i=0; i<genl;i++)

            scanf ("%d", &gen[i]);

            tlen=frl+genl-1;

                        for(i=frl;i<tlen;i++)

                        {

                        dupfr[i] =0;

                        }

                        remainder(dupfr);

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

                        {

                        recfr[i]=fr[i];

                        }

                                    for(i=frl,j=1;j<genl;i++,j++)

                                    {

                                    recfr[i]=rem[j];

                                    }

                        remainder(recfr);

                        flag=0;

                        for(i=0;i<4;i++)

                        {

                        if(rem[i]!=0)

                        flag++;

                        }

            if (flag==0)

            {

            printf ("Frame is received correctly\n");

            }

            else

            {

            printf ("The received frame is wrong\n");

            }

}

            remainder (int fr[])

            {

            int k,k1,i,j;

            for(k=0;k<frl;k++)

            {

                        if (fr[k]==1)

                        {

                        k1=k;

                                    for (i=0,j=k;i<genl;i++,j++)

                                    {

                                    rem[i]=fr[j]^gen[i];

                                    }

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

                        {

                        fr[k1]=rem[i];

                        k1++;

                        }

                        }

            }

return 0;

}

OUTPUT CONSOLE:

    }