Implement on a data set of characters the three CRC polynomials – CRC 12, CRC 16 and CRC CCIP.

Implement on a data set of characters the three CRC polynomials – CRC 12, CRC 16 and CRC CCIP.

Introduction to Cyclic Redundancy Check:

CRC method can detect a single burst of length n, since only one bit per column will be changed, a burst of length n+1 will pass undetected, if the first bit is inverted, the last bit is inverted and all other bits are correct. If the block is badly garbled by a long burst or by multiple shorter burst, the probability that any of the n columns will have the correct parity that is 0.5. so the probability of a bad block being expected when it should not be 2 power(-n). This scheme sometimes is known as Cyclic Redundancy Code.

Program Algorithm/Flowchart:

Begin

Step 1:Declare I, j , fr[8], dupfr[11], recfr[11], tlen, flag, gen[4], genl, frl, rem[4] as integer

Step 2: initialize frl=8 and genl=4

Step 3: initialize i=0

Step 4: Repeat step(5to7) until i<frl

Step 5: read fr[i]

Step 6: dupfr[i]=fr[i]

Step 7: increment i

Step 8: initialize i=0

Step 9: repeat step(10to11) until i<genl

Step 10: read gen[i]

Step 11: increment i

Step 12: tlen=frl+genl-1

Step 13: initialize i=frl

Step 14: Repeat step(15to16) until i<tlen

Step 15: dupfr[i]=0

Step 16: increment i

Step 17: call the function remainder(dupfr)

Step 18: initialize i=0

Step 19: repeat step(20 to 21) until j<genl

Step 20: recfr[i]=rem[j]

Step 21: increment I and j

Step 22: call the function remainder(dupfr)

Step 23: initialize flag=0 and i=0

Step 24: Repeat step(25to28) until i<4

Step 25: if rem[i]!=0 then

Step 26: increment flag

Step 27: end if

Step 28: increment i

Step 29: if flag=0 then

Step 25: print frame received correctly

Step 25: else

Step 25: print the received frame is wrong

End

Function: Remainder(int fr[])

Begin

Step 1: Declare k,k1,I,j as integer

Step 2: initialize k=0;

Step 3: repeat step(4 to 14) until k< frl

Step 4: if ((fr[k] == 1) then

Step 5: k1=k

Step 6: initialize i=0, j=k

Step 7: repeat step(8 to 9) until i< genl

Step 8: rem[i] =fr[j] exponential gen[i]

Step 9: increment I and j

Step 10: initialize I = 0

Step 11: repeat step(12to13) until I <genl

Step 12: fr[k1] = rem[i]

Step 13: increment k1 and i

Step 14: end if

End

Program Code: // Program for Cyclic Redundency 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:");

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

{

scanf("%d",&fr[i]);

dupfr[i]=fr[i];

}

printf("Enter generator:");

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 received correctly");

}

else

{

printf("the received frame is wrong");

}

}

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++;

}

}

}

}

Program Output:

Enter frame: MLRITM

Enter generator: frame received correctly

------------------

(program exited with code: 24)

Press return to continue