hysteresis.cpp

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/**
 * @file hysteresis.cpp
 *
 * @author Julian Oes <julian@oes.ch>
 */

#include "hysteresis.h"

namespace systemlib
{

void
Hysteresis::set_hysteresis_time_from(const bool from_state, const hrt_abstime new_hysteresis_time_us)
{
    if (from_state) {
        _time_from_true_us = new_hysteresis_time_us;

    } else {
        _time_from_false_us = new_hysteresis_time_us;
    }
}

void
Hysteresis::set_state_and_update(const bool new_state, const hrt_abstime &now_us)
{
    if (new_state != _state) {
        if (new_state != _requested_state) {
            _requested_state = new_state;
            _last_time_to_change_state = now_us;
        }

    } else {
        _requested_state = _state;
    }

    update(now_us);
}

void
Hysteresis::update(const hrt_abstime &now_us)
{
    if (_requested_state != _state) {

        const hrt_abstime elapsed = now_us - _last_time_to_change_state;

        if (_state && !_requested_state) {
            // true -> false
            if (elapsed >= _time_from_true_us) {
                _state = false;
            }

        } else if (!_state && _requested_state) {
            // false -> true
            if (elapsed >= _time_from_false_us) {
                _state = true;
            }
        }
    }
}

} // namespace systemlib