Hysteresis.hpp

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#pragma once
 
#include <AH/Settings/Warnings.hpp>
AH_DIAGNOSTIC_WERROR() // Enable errors on warnings
 
#include <stdint.h>
 
 
template <uint8_t BITS, class T_in = uint16_t, class T_out = uint8_t>
class Hysteresis {
  public:
    bool update(T_in inputLevel) {
        T_in prevLevelFull = (T_in(prevLevel) << BITS) | offset;
        T_in lowerbound = prevLevel > 0 ? prevLevelFull - margin : 0;
        T_in upperbound = prevLevel < max_out ? prevLevelFull + margin : max_in;
        if (inputLevel < lowerbound || inputLevel > upperbound) {
            setValue(inputLevel);
            return true;
        }
        return false;
    }
 
    T_out getValue() const { return prevLevel; }
 
    void setValue(T_in inputLevel) { prevLevel = inputLevel >> BITS; }
 
  private:
    T_out prevLevel = 0;
    constexpr static T_in margin = (1UL << BITS) - 1;
    constexpr static T_in offset = 1UL << (BITS - 1);
    constexpr static T_in max_in = -1;
    constexpr static T_out max_out = static_cast<T_out>(max_in >> BITS);
    static_assert(max_in > 0, "Error: only unsigned types are supported");
};
 
 
AH_DIAGNOSTIC_POP()