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    extern crate kawaii;

    use std::time::Duration;
    use std::thread;
    use std::thread::JoinHandle;
    use std::sync::Arc;
    use std::sync::atomic::{AtomicBool, Ordering};

    use self::kawaii::gpio::{AsyncPort, Edge, Value};

    #[cfg(feature = "measure")]
    use self::kawaii::Measure;

    #[derive(Debug)]
    pub struct EmergencyStop {
        thread: Option<JoinHandle<()>>,
        pub state: Arc<AtomicBool>,
    }

    impl EmergencyStop {
        /// Constructs a new `EmergencyStop` and starts poll thread.
        ///
        /// # Parameter
        /// - `stop_port` GPIO Port number of emergency stop pin.
        pub fn new(stop_port: u8) -> std::io::Result<Self> {
            let name = format!("EmergencyStop(port = {})", stop_port);
            let state = Arc::new(AtomicBool::new(false));
            let mut port = AsyncPort::new(stop_port, Edge::Both)?;

            let state_clone = state.clone();
            let thread = thread::Builder::new()
                .name(name)
                .spawn(move || EmergencyStop::thread(&mut port, state_clone))?;

            Ok(EmergencyStop {
                thread: Some(thread),
                state: state,
            })
        }

        /// Emergency stop poll thread
        fn thread(port: &mut AsyncPort, state: Arc<AtomicBool>) {
            #[cfg(feature = "measure")]
            let mut measure = Measure::new(format!("EmergencyStop(port = {})", port.port.number));

            // clear first value
            port.poll(Some(Duration::new(0, 0))).is_ok();

            while !state.load(Ordering::Relaxed) {
                #[cfg(feature = "measure")]
                measure.start();

                let timeout = Some(Duration::new(1, 0));

                #[cfg(not(feature = "measure"))]
                let value = port.poll(timeout);

                #[cfg(feature = "measure")]
                let value = port.poll_measure(timeout, &mut measure);

                // continue on timeout
                match value {
                    Ok(value) => {
                        if let Some(value) = value {
                            match value {
                                Value::High => {
                                    #[cfg(debug_assertions)]
                                    println!("EmergencyStop! ({:?})", value);

                                    state.store(true, Ordering::Relaxed);
                                }
                                _ => {
                                    #[cfg(debug_assertions)]
                                    println!("EmergencyStop ignored: ({:?})", value);
                                }
                            }
                        }
                    }
                    Err(e) => {
                        #[cfg(debug_assertions)]
                        println!("EmergencyStop! ({:?})", e);

                        state.store(true, Ordering::Relaxed);
                    }
                }

                #[cfg(feature = "measure")]
                measure.stop();
            }
        }
    }

    impl Drop for EmergencyStop {
        /// Set emergency stop and join poll thread.
        fn drop(&mut self) {
            self.state.store(true, Ordering::Relaxed);

            if let Some(thread) = self.thread.take() {
                thread.join().is_ok();
            }
        }
    }

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