struct NestedLoopList list;
if ((*arg_ptr).ptr_type == 0)
{
   /* array */
   struct NestedLoopArrayArg* array_ptr = (*arg_ptr).ptr;
   list.elem_size = (*array_ptr).elem_size;
   list.length    = (*array_ptr).length;
   list.ptr       = (*array_ptr).ptr;
   list.free_ptr  = 0;
}
else 
{
   /* function */
   struct NestedLoopFuncArg* func_ptr = (*arg_ptr).ptr;
   (*(*func_ptr).ptr)(&list, (*func_ptr).pad);
}