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/**
 * First order "alpha" IIR digital filter
 * @author Mathieu Bresciani <brescianimathieu@gmail.com>
 */

#pragma once

template <typename T>
class AlphaFilter final {
public:
	AlphaFilter() = default;
	~AlphaFilter() = default;

	void reset(const T &val) { _x = val; }

	void update(const T &input, float tau, float dt) {
		const float alpha = dt / tau;
		update(input, alpha);
	}

	void update(const T &input, float alpha) { _x = (1.f - alpha) * _x + alpha * input; }

	// Typical 0.9/0.1 lowpass filter
	void update(const T &input) { update(input, 0.1f); }

	const T &getState() const { return _x; }

private:
	T _x{};  ///< current state of the filter
};