mavlink_stream.h

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/**
 * @file mavlink_stream.h
 * Mavlink messages stream definition.
 *
 * @author Anton Babushkin <anton.babushkin@me.com>
 */

#ifndef MAVLINK_STREAM_H_
#define MAVLINK_STREAM_H_

#include <drivers/drv_hrt.h>
#include <px4_platform_common/module_params.h>
#include <containers/List.hpp>

class Mavlink;

class MavlinkStream : public ListNode<MavlinkStream *>
{

public:

    MavlinkStream(Mavlink *mavlink);
    virtual ~MavlinkStream() = default;

    // no copy, assignment, move, move assignment
    MavlinkStream(const MavlinkStream &) = delete;
    MavlinkStream &operator=(const MavlinkStream &) = delete;
    MavlinkStream(MavlinkStream &&) = delete;
    MavlinkStream &operator=(MavlinkStream &&) = delete;

    /**
     * Get the interval
     *
     * @param interval the interval in microseconds (us) between messages
     */
    void set_interval(const int interval) { _interval = interval; }

    /**
     * Get the interval
     *
     * @return the inveral in microseconds (us) between messages
     */
    int get_interval() { return _interval; }

    /**
     * @return 0 if updated / sent, -1 if unchanged
     */
    int update(const hrt_abstime &t);
    virtual const char *get_name() const = 0;
    virtual uint16_t get_id() = 0;

    /**
     * @return true if steam rate shouldn't be adjusted
     */
    virtual bool const_rate() { return false; }

    /**
     * Get maximal total messages size on update
     */
    virtual unsigned get_size() = 0;

    /**
     * Get the average message size
     *
     * For a normal stream this equals the message size,
     * for something like a parameter or mission message
     * this equals usually zero, as no bandwidth
     * needs to be reserved
     */
    virtual unsigned get_size_avg() { return get_size(); }

    /**
     * @return true if the first message of this stream has been sent
     */
    bool first_message_sent() const { return _first_message_sent; }

    /**
     * Reset the time of last sent to 0. Can be used if a message over this
     * stream needs to be sent immediately.
     */
    void reset_last_sent() { _last_sent = 0; }

protected:
    Mavlink      *const _mavlink;
    int _interval{1000000};     ///< if set to negative value = unlimited rate

    virtual bool send(const hrt_abstime t) = 0;

    /**
     * Function to collect/update data for the streams at a high rate independant of
     * actual stream rate.
     *
     * This function is called at every iteration of the mavlink module.
     */
    virtual void update_data() { }

private:
    hrt_abstime _last_sent{0};
    bool _first_message_sent{false};
};


#endif /* MAVLINK_STREAM_H_ */