Hamming Code 2

#include<stdio.h> #include<math.h> #include<string.h> #define MAXINT 65536 #define SIZE 100 int arr[SIZE][SIZE]; // a global array , to contain table information int ele=0,ind=0; // indices to be used in above array void summ(int i) { /* The method to initialize contents of global array by power of 2's sum for each entry */ int j=0; //index no if(isPow2(i)) { /*input no i is of power of 2's form like 1,2,4,8,16...*/ arr[ele][ind]=calcPow(i); /*calculate what's the power of 2 , in the no, & store to global array*/ ind++; } else { /*input no i is NOT of power of 2's form */ j=findLowerOf2(i); /* try to find just last no , which is of form of power of 2 */

of 2 */

arr[ele][ind]=calcPow(j); /* again calculate the power*/ ind++; i=i-j; /* differnce in the no & the last no which is of form of power /*now call method recursively for the new no (i=i-j) */ summ(i);

}

}

int isPow2(int i) { /*if input no is power of two retrun 1 , else 0*/ if(MAXINT % i==0) return 1; //true return 0; //false } int calcPow(int i) { /*Thism ethod returns , what is power of 2 , in a no. which is of form 2 to the power p */ /* return p , from input of format 2^p */ int count=-1; /* validate */ if(!isPow2(i)) printf("flow error... ");

else while(i>0) { i/=2; count++; } }

return count;

int findLowerOf2(int i) { /*a function to calculate the no , JUST below i , which is power of 2 */ int count=-1; if(isPow2(i)) return pow(2,i); else while(i>0) { i/=2; count++; } return pow(2,count); } void callSumm(int i) { /* A method to call summ() method , with assertion that all global parameters are incremented at each call to summ() */ ind=0; summ(i); arr[ele][ind++]=-1; ele++; } void dieError() { /* If failure , exit the program*/ exit(1); } int howManyTimes(int val,int a[]) { /* a method to check that how many times no val is occuring in array a[] */ int i,count=0; for(i=0;a[i]!=-1;i++) if(a[i]==val) count++; return count; } void checkInput(int argc,char str[]) {

int i=0; if (argc<2) { printf("usage: filename.o 'The code string' "); printf(" ex. a.out 110110 "); dieError(); } for(i=0;i<strlen(str);i++) if(!(str[i]=='0' || str[i]=='1')) { printf("Please enter a binary string only..... "); dieError(); } } int calr(int m) { /*Method to calculate checksum bits for given m , databits */ int r=0; for(r=0;r<=m;r++) if(m <= pow(2,r)-1-r) return r; } int isEven(int i) { return i%2==0; } int main(int argc,char *argv[]) { /* Declaretions ...*/ /* flag & index variables*/ int i,j,k=0,flag,temp; /* The output codeword container */ char coded[SIZE]; int len; //total length of coded word int m; //code bits int r; //check bits /* to associate & contain equations of checkbits */ int count[SIZE][SIZE]; /* validate input */ checkInput(argc,argv[1]); /*calculate no of check bits required n thus total length */ m=strlen(argv[1]); r=calr(m); len=m+r;

/* Fill the global container , of m,r & len */ for(i=1;i<=len;i++) callSumm(i);

according to the size info

for(j=0,k=0;j
count[j][k]=-1;

/*Fill the code word....,except check bits*/ for(i=0,j=0;j
"); }

for(i=0;i