hysteresis.h
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/****************************************************************************
*
* Copyright (c) 2016-2019 PX4 Development Team. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. Neither the name PX4 nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
****************************************************************************/
/**
* @file hysteresis.h
*
* Hysteresis of a boolean value.
*
* @author Julian Oes <julian@oes.ch>
*/
#pragma once
#include <drivers/drv_hrt.h>
namespace systemlib
{
class Hysteresis
{
public:
explicit Hysteresis(bool init_state) :
_state(init_state),
_requested_state(init_state)
{}
Hysteresis() = delete; // no default constructor
~Hysteresis() = default;
bool get_state() const { return _state; }
void set_hysteresis_time_from(const bool from_state, const hrt_abstime new_hysteresis_time_us);
void set_state_and_update(const bool new_state, const hrt_abstime &now_us);
void update(const hrt_abstime &now_us);
private:
hrt_abstime _last_time_to_change_state{0};
hrt_abstime _time_from_true_us{0};
hrt_abstime _time_from_false_us{0};
bool _state;
bool _requested_state;
};
} // namespace systemlib