Binary Multiplication in C

This is a dynamic program which accepts two integer from the console and convert them to Binary Numbers.
After converting them, they are multiplied by repetitive addition and the result is then displayed in the console !
Binary Multiplication is highly necessary because computer only understands the addition. In case of multiplication it’s repetitive addition.

Screenshots [Demo]

The Code:

#include<stdio.h>
#include<malloc.h>
int *q,*m,*c,n,d,siz;
int powr(int x,int y)
{
 int s=1,i;
 for(i=0;i<y;i++)
   s=s*x;
 return s;
}
void bin(int n, int arr[]){
    int r, i = 0;
    do{
        r = n % 2;
        n /= 2;
        arr[i] = r;
        i++;
    }while(n > 0);
 }
void set(int array[], int x){
    int i,tmp[20]={0};
    for(i = x -1; i >=0; i--)
  tmp[x-1-i]=array[i];
 for(i=0;i<x;i++)
  array[i]=tmp[i];
 }
int len(int x)
{
 int i=0;
 while(powr(2,i)<=x) i++;
 return ++i;
}
void print(int arr[],int n)
{
 int i;
 for(i=0;i<n;i++)
  printf("%d ",arr[i]);
}
void addBinary(int a1[], int a2[])
{
    int bi[2]={0},ca[20]={0};
    int t=siz,tmp=0;
    int *su=(int*)malloc(sizeof(int)*siz);
 while(t-->0)
 {
  tmp=a1[t]+a2[t]+ca[t];
  bin(tmp,bi);
  su[t]=bi[0];
  ca[t-1]=bi[1];
  bi[0]=0;bi[1]=0;
 }
 for(t=0;t<siz;t++)
  a1[t]=su[t];
 free(su);
 }
int main()
{
 int i;
 printf("Enter two numbers a*b : ");
 scanf("%d*%d",&n,&d);
 siz=(len(n)+len(d))-2;
 q=(int*)malloc(sizeof(int)*siz);
 bin(d,q);
 m=(int*)malloc(sizeof(int)*siz);
 bin(d,m);
 set(q,siz);
 set(m,siz);
 for(i=1;i<n;i++)
  addBinary(q,m);
 print(q,siz);
 return 0;
}