ardupilot/libraries/AP_Frsky_Telem/AP_Frsky_SPort.h

#pragma once

#include "AP_Frsky_Backend.h"

class AP_Frsky_SPort : public AP_Frsky_Backend
{

public:

    using AP_Frsky_Backend::AP_Frsky_Backend;

    void send() override;

    typedef union {
        struct PACKED {
            uint8_t sensor;
            uint8_t frame;
            uint16_t appid;
            uint32_t data;
        };
        uint8_t raw[8];
    } sport_packet_t;

protected:

    void send_sport_frame(uint8_t frame, uint16_t appid, uint32_t data);

    struct PACKED {
        bool send_latitude; // sizeof(bool) = 4 ?
        uint32_t gps_lng_sample;
        uint8_t new_byte;
    } _passthrough;

    uint32_t calc_gps_latlng(bool &send_latitude);

    static uint8_t calc_sensor_id(const uint8_t physical_id);

private:

    struct {
        bool sport_status;
        bool gps_refresh;
        bool vario_refresh;
        uint8_t fas_call;
        uint8_t gps_call;
        uint8_t vario_call;
        uint8_t various_call;
    } _SPort;
};