mavlink_simple_analyzer.h

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/**
 * @file mavlink_simple_analyzer.h
 *
 * @author Achermann Florian <acfloria@ethz.ch>
 */

#pragma once

#include <float.h>
#include <stdint.h>

/**
 * SimpleAnalyzer
 *
 * Class used for simple analysis of data streams.
 * The data can be analyzed in the following three modes:
 *
 * AVERAGE:
 *      The average value is computed at the beginning. Based on the number of analyzed values,
 *      the update rate and the window size the switch to the moving average is determined.
 *
 * MIN:
 *      The minimum value is tracked.
 *
 * MAX:
 *      The maximum value is tracked.
 */
class SimpleAnalyzer
{
public:
    enum Mode {
        AVERAGE = 0,
        MIN,
        MAX,
    };

    /**
     * Constructor
     *
     * Defines the mode of the analyzer and the window size in case of the
     * averaging mode.
     *
     * @param[in] mode: The mode of the analyzer
     * @param[in] window: The window size in seconds. Only used in the averaging mode.
     */
    SimpleAnalyzer(Mode mode, float window = 60.0f);

    /**
     * Reset the analyzer to the initial state.
     */
    void reset();

    /**
     * Add a new value to the analyzer and update the result according to the mode.
     *
     * @param[in] val: The value to process
     * @param[in] update_rate: The update rate in [1/s] for which new value are added.
     *      Used in the averaging mode to determine when to switch from averaging to the moving average.
     */
    void add_value(float val, float update_rate);

    /**
     * Returns true if at least one value has been added to the analyzer.
     */
    bool valid() const;

    /**
     * Get the current result of the analyzer.
     */
    float get() const;

    /**
     * Get the scaled value of the current result of the analyzer.
     *
     * @param[in] scalingfactor: The factor used to scale the result.
     */
    float get_scaled(float scalingfactor) const;

    /**
     * Get the rounded scaled value casted to the input template type.
     * Should only be used to return integer types.
     *
     * @param[out] ret: The scaled and rounded value of the current analyzer result.
     * @parma[in] scalingfactor: The factor which is used to scale the result.
     */
    void get_scaled(uint8_t &ret, float scalingfactor) const
    {
        float avg = get_scaled(scalingfactor);
        int_round(avg);
        check_limits(avg, 0, UINT8_MAX);

        ret = static_cast<uint8_t>(avg);
    }

    void get_scaled(int8_t &ret, float scalingfactor) const
    {
        float avg = get_scaled(scalingfactor);
        int_round(avg);
        check_limits(avg, INT8_MIN, INT8_MAX);

        ret = static_cast<int8_t>(avg);
    }

private:
    unsigned int _n = 0; /**< The number of added samples */
    float _window = 60.0f; /**< The window size for the moving average filter [s] */
    Mode _mode = AVERAGE; /**< The mode of the simple analyzer */
    float _result = 0.0f; /**< The result of the analyzed data. */

    void check_limits(float &x, float min, float max) const;
    void int_round(float &x) const;
};

void convert_limit_safe(float in, uint16_t &out);
void convert_limit_safe(float in, int16_t &out);