ardupilot/libraries/AP_RangeFinder/AP_RangeFinder_Backend_CAN.h

#pragma once

#include "AP_RangeFinder_Backend.h"

#if HAL_MAX_CAN_PROTOCOL_DRIVERS

#include <AP_CANManager/AP_CANSensor.h>
#include <AP_BoardConfig/AP_BoardConfig.h>

class RangeFinder_MultiCAN;

class AP_RangeFinder_Backend_CAN : public AP_RangeFinder_Backend
{
public:
    // constructor
    AP_RangeFinder_Backend_CAN(RangeFinder::RangeFinder_State &_state,
                                  AP_RangeFinder_Params &_params);

    friend class RangeFinder_MultiCAN;

    static const struct AP_Param::GroupInfo var_info[];

protected:

    // update state
    virtual void update(void) override;

    // get distance measurement
    bool get_reading(float &reading_m);

    // it is essential that anyone relying on the base-class update to implement this
    virtual bool handle_frame(AP_HAL::CANFrame &frame) = 0;

    // maximum time between readings before we change state to NoData:
    virtual uint32_t read_timeout_ms() const { return 200; }

    virtual MAV_DISTANCE_SENSOR _get_mav_distance_sensor_type() const override {
        return MAV_DISTANCE_SENSOR_RADAR;
    }

    // return true if the CAN ID is correct
    bool is_correct_id(uint32_t can_id) const;

    // set distance and count
    void accumulate_distance_m(float distance_m) {
        _distance_sum += distance_m;
        _distance_count++;
    };

    // linked list
    AP_RangeFinder_Backend_CAN *next;

    AP_Int32 receive_id; // CAN ID to receive for this backend
    AP_Int32 snr_min; // minimum signal strength to accept packet

private:

    float _distance_sum; // meters
    uint32_t _distance_count;
};

// a class to allow for multiple CAN backends with one
// CANSensor driver
class RangeFinder_MultiCAN : public CANSensor {
public:
    RangeFinder_MultiCAN(AP_CAN::Protocol can_type, const char *driver_name) : CANSensor(driver_name) {
        register_driver(can_type);
    }

    // handler for incoming frames
    void handle_frame(AP_HAL::CANFrame &frame) override;

    // Semaphore for access to shared backend data
    HAL_Semaphore sem;
    AP_RangeFinder_Backend_CAN *drivers;
};

#endif // HAL_MAX_CAN_PROTOCOL_DRIVERS