make exec speed configurable

crsn_stacks/src/exec.rs

@@ -48,6 +48,10 @@ impl OpTrait for StackOp {
                     let obj: &mut Stacks = state.ext_mut();
                     let val = obj.stacks[stack_num as usize].pop_back();
 
+                    if obj.stacks[stack_num as usize].is_empty() {
+                        state.frame.status.zero = true;
+                    }
+
                     let val = match val {
                         None => {
                             state.frame.status.overflow = true;