// check whether an ack resets temporary blocking of cb's 
interface IAsync {
  in void e();
  in void c();
  out void cb();

  behaviour {
    bool idle = true;
    [idle] {
      on e: idle = false;
      on c: {}
    }
    [!idle] {
      on e: illegal;
      on c: idle = true;
      on inevitable: { cb; idle = true; }
    }
  }
}


component async_prio3 {
  provides IAsync p;
  requires IAsync r;
  behaviour {
    enum State { S0, S1, S2 };
    requires dzn.async i;
    State s = State.S0;
    [s.S0] {
      on p.e(): { i.req(); r.e(); s = State.S1; }
    }
    [s.S1] {
      on i.ack(): { s = State.S2; } 
    }
    [s.S2] {
      on r.cb(): { p.cb(); s = State.S0; }
    }
    on p.c(): { i.clr(); r.c(); s = State.S0; }
  }
}