Write a program for error detection and correction for 7/8 bits ASCII codes using Hamming Codes or CRC.

Write a program for error detection and correction for 7/8 bits ASCII codes using Hamming Codes or CRC.

  10:54 PM    Dnyaneshwar Kudande

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Write a program for error detection and correction for 7/8 bits ASCII codes using Hamming Codes or CRC.

//Code for 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]);
//if (rem ==0)
//printf("Error in the code");
//else
//printf("\nNo Error detected%d",rem);
//getch();

}


//Code for Hamming
#include<stdio.h>
#include <curses.h>

int main() {
    int data[10];
    int dataatrec[10],c,c1,c2,c3,i;
    //clrscr();
    printf("Enter 4 bits of data one by one\n");
    scanf("%d",&data[0]);
    scanf("%d",&data[1]);
    scanf("%d",&data[2]);
    scanf("%d",&data[4]);

    //Calculation of even parity
    data[6]=data[0]^data[2]^data[4];
    data[5]=data[0]^data[1]^data[4];
    data[3]=data[0]^data[1]^data[2];

    printf("\nEncoded data is\n");
    for(i=0;i<7;i++)
        printf("%d",data[i]);

    printf("\n\nEnter received data bits one by one\n");
    for(i=0;i<7;i++)
        scanf("%d",&dataatrec[i]);

    c1=dataatrec[6]^dataatrec[4]^dataatrec[2]^dataatrec[0];
    c2=dataatrec[5]^dataatrec[4]^dataatrec[1]^dataatrec[0];
    c3=dataatrec[3]^dataatrec[2]^dataatrec[1]^dataatrec[0];
    c=c3*4+c2*2+c1 ;

    if(c==0) {
        printf("\nNo error while transmission of data\n");
    }
    else {
        printf("\nError on position %d",c);
       
        printf("\nData sent : ");
        for(i=0;i<7;i++)
            printf("%d",data[i]);
       
        printf("\nData received : ");
        for(i=0;i<7;i++)
            printf("%d",dataatrec[i]);
       
        printf("\nCorrect message is\n");

        //if errorneous bit is 0 we complement it else vice versa
        if(dataatrec[7-c]==0)
            dataatrec[7-c]=1;
        else
            dataatrec[7-c]=0;
       
        for (i=0;i<7;i++) {
            printf("%d",dataatrec[i]);
           
            return 0;
        }
    }
getchar ();
}