double myList[100];
int head, tail ;
// Do not initialize inputs!
void Init(void)
{
  head = 0;
  tail = 0;
}

void Exec(void)
{
if(*v->En == 1){
  myList[tail] = *v->In;
  //tail = (tail+1)% v->Count;
  v->Out = myList[tail] -  myList[head] ;
  v->head = head;
  v->tail = tail;

  if(tail + 1 >= v->Count) tail = 0; else tail++;
  if(tail == head)
    if(head+1 >= v->Count) head = 0; else head++;
  }
}