Notes

//CRC
#include<stdio.h>
#include<conio.h>
#include<string.h>
void main()
{
int i, j, keylen, msglen;
char input[100], key[30], temp[30], quot[100], rem[30], key1[30];
clrscr();
printf("Enter Data: ");
gets(input);
printf("Enter Key: ");
gets(key);
keylen = strlen(key);
msglen = strlen(input);
strcpy(key1, key);
for (i = 0; i < keylen - 1; i++)
{
input[msglen + i] = '0';
}
for (i = 0; i < keylen; i++)
temp[i] = input[i];
for (i = 0; i < msglen; i++)
{
quot[i] = temp[0];
if (quot[i] == '0')
for (j = 0; j < keylen; j++)
key[j] = '0';
else
for (j = 0; j < keylen; j++)
key[j] = key1[j];
for (j = keylen - 1; j > 0; j--)
{
if (temp[j] == key[j])
rem[j - 1] = '0';
else
rem[j - 1] = '1';
}
rem[keylen - 1] = input[i + keylen];
strcpy(temp, rem);
}
strcpy(rem, temp);
printf("nQuotient is ");
for (i = 0; i < msglen; i++)
printf("%c", quot[i]);
printf("nRemainder is ");
for (i = 0; i < keylen - 1; i++)
printf("%c", rem[i]);
printf("nFinal data is: ");
for (i = 0; i < msglen; i++)
printf("%c", input[i]);
for (i = 0; i < keylen - 1; i++)
printf("%c", rem[i]);
getch();
}
// Bit stuffing
#include <stdio.h>
#include <string.h>

// Function for bit stuffing
void bitStuffing(int N, int arr[])
{
// Stores the stuffed array
int brr[30];

// Variables to traverse arrays
int i=0, j=0, k;

// Stores the count of consecutive ones
int count = 1;

// Loop to traverse in the range [0, N)
while (i < N)
{
// If the current bit is a set bit
if (arr[i] == 1)
{
// Insert into array brr[]
brr[j] = arr[i];

// Loop to check for next 5 bits
for (k = i + 1; arr[k] == 1 && k < N && count < 5; k++)
{
j++;
brr[j] = arr[k];
count++;

// If 5 consecutive set bits are found insert a 0 bit
if (count == 5)
{
j++;
brr[j] = 0;
}
i = k;
}
}

// Otherwise insert arr[i] into the array brr[]
else
{
brr[j] = arr[i];
}
i++;
j++;
}
// Print Answer
for (i = 0; i < j; i++)
{
printf("%d", brr[i]);
}
}
// Driver Code
int main()
{
int N = 6;
int arr[] = {1, 1, 1, 1, 1, 1};

bitStuffing(N, arr);

return 0;
}
//Byte stuffing
#include <stdio.h>
#include <string.h>
main()
{
char a[20], b[20];
int i, n, j;
char f, s;
printf("Enter the size of the frame : ");
scanf("%d", &n);
n = n * 2;
printf("nEnter the characters in frame : n");
for (i = 0; i < n; i++)
scanf("%c", &a[i]);
printf("n FRAME n ");
for (i = 0; i < n; i++)
printf("%c", a[i]);
j = 0;
for (i = 0; i < n; i++)
{
if (a[i] == 'f')
{
b[j] = 's';
j++;
b[j] = a[i];
}
else if (a[i] == 's')
{
b[j] = 's';
j++;
b[j] = a[i];
}
else
b[j] = a[i];

j++;
}
printf("n RESULT n");
printf("f");
for (i = 0; i < j; i++)
{
printf("n");
printf("%c", b[i]);
}
printf("nf");
}
//Checksum
#include <stdio.h>
#include <string.h>

int main()
{
char a[20], b[20];
char sum[20], complement[20];
int i, length;

printf("Enter first binary stringn");
scanf("%s", &a);
printf("Enter second binary stringn");
scanf("%s", &b);

if (strlen(a) == strlen(b))
{
length = strlen(a);
char carry = '0';

for (i = length - 1; i >= 0; i--)
{
if (a[i] == '0' && b[i] == '0' && carry == '0')
{
sum[i] = '0';
carry = '0';
}
else if (a[i] == '0' && b[i] == '0' && carry == '1')
{
sum[i] = '1';
carry = '0';
}
else if (a[i] == '0' && b[i] == '1' && carry == '0')
{
sum[i] = '1';
carry = '0';
}
else if (a[i] == '0' && b[i] == '1' && carry == '1')
{
sum[i] = '0';
carry = '1';
}
else if (a[i] == '1' && b[i] == '0' && carry == '0')
{
sum[i] = '1';
carry = '0';
}
else if (a[i] == '1' && b[i] == '0' && carry == '1')
{
sum[i] = '0';
carry = '1';
}
else if (a[i] == '1' && b[i] == '1' && carry == '0')
{
sum[i] = '0';
carry = '1';
}
else if (a[i] == '1' && b[i] == '1' && carry == '1')
{
sum[i] = '1';
carry = '1';
}
else{
break;
}
}

printf("nSum=%c%s", carry, sum);
for (i = 0; i < length; i++)
{
if (sum[i] == '0'){
complement[i] = '1';
}
else{

complement[i] = '0';
}
}

if (carry == '1'){
carry = '0';
}
else{
carry = '1';
}

printf("nChecksum=%c%sn", carry, complement);
printf("n");
}
else
{
printf("nWrong input strings");
}
}