void * cpstr(void * str, int strln, void  *start, unsigned int num){
int vl=0;
void * pos;
 if (strln == 1){
   memset(start,*(char *)str,num);
   return (char *)start+num;
 }
 while (num){
   while (!(num % 2)){
     vl++;
     num=num>>1;
   } 
   pos=mempcpy(start,str,strln);
   num=num-1;
   str=start;
   while (vl){
     pos=mempcpy(pos,start,strln);
     strln=strln<<1;
     vl--;
   }
   start=pos;
  }
 return start;
}