ToneAlarm.h

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/**
 * @file ToneAlarm.h
 *
 * Low Level Driver for the PX4 audio alarm port. Subscribes to
 * tune_control and plays notes on this architecture specific timer HW.
 */

#pragma once

#include <circuit_breaker/circuit_breaker.h>
#include <drivers/device/device.h>
#include <drivers/drv_tone_alarm.h>
#include <lib/tunes/tunes.h>
#include <px4_platform_common/defines.h>
#include <px4_platform_common/px4_work_queue/ScheduledWorkItem.hpp>
#include <uORB/Subscription.hpp>
#include <uORB/topics/tune_control.h>

#include <string.h>

#if !defined(UNUSED)
#  define UNUSED(a) ((void)(a))
#endif

class ToneAlarm : public cdev::CDev, public px4::ScheduledWorkItem
{
public:
    ToneAlarm();
    ~ToneAlarm();

    /**
     * @brief Initializes the character device and hardware registers.
     */
    int init() override;

    /**
     * @brief Prints the driver status to the console.
     */
    void status();

protected:

    /**
     * @brief Parses the next note out of the string and plays it.
     */
    void next_note();

    /**
     * @brief Trampoline for the work queue.
     */
    void Run() override;

    /**
     * @brief Updates the uORB topics for local subscribers.
     */
    void orb_update();

    /**
     * @brief Starts playing the note.
     */
    void start_note(unsigned frequency);

    /**
     * @brief Stops playing the current note and makes the player 'safe'.
     */
    void stop_note();

    volatile bool _running{false};      ///< Flag to indicate the current driver status.

    int _cbrk{CBRK_UNINIT};             ///< If true, no audio output.

private:

    volatile bool _should_run{true};

    bool _play_tone{false};

    unsigned int _silence_length{0};    ///< If nonzero, silence before next note.

    uORB::Subscription _tune_control_sub{ORB_ID(tune_control)};

    tune_control_s _tune{};

    Tunes _tunes = Tunes();
};