EEPROM-Base.h

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// Copyright © 2017-2025 Daniel Porrey. All Rights Reserved.
//
// This file is part of the EEPROM-Storage library.
//
// EEPROM-Storage library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// EEPROM-Storage library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with EEPROM-Storage library. If not,
// see http://www.gnu.org/licenses/.
//
#pragma once
#ifndef EEPROM_BASE_H
#define EEPROM_BASE_H
 
//
// Cross-compatable with Arduino, GNU C++ for tests, and Particle.
//
#if defined(ARDUINO) && ARDUINO >= 100
  #include <Arduino.h>
  #include <EEPROM.h>
#elif defined(PARTICLE)
  #include <Particle.h>
#endif
 
#include "EEPROM-Util.h"
#include "EEPROM-Checksum.h"
 
template <typename T>
class EEPROMBase
{
  public:
    EEPROMBase(const uint address)
    {
      this->_address = this->normalizeAddress(address);
    }
 
    EEPROMBase(const uint address, T defaultValue) : EEPROMBase(address)
    {
      this->_defaultValue = defaultValue;
    }
 
    operator T()
    {
      return this->get();
    }
 
    byte operator[] (const uint index)
    {
      uint address = this->normalizeAddress(this->getAddress() + index);
      return EEPROM[address];
    }
 
    T operator ++ (int)
    {
      T oldValue = this->get();
      this->set(oldValue + 1);
      return oldValue;
    }
 
    T operator ++ ()
    {
      return this->set(this->get() + 1);
    }
 
    T operator -- (int)
    {
      T oldValue = this->get();
      this->set(this->get() - 1);
      return oldValue;
    }
 
    T operator -- ()
    {
      return this->set(this->get() - 1);
    }
 
    T operator += (T const& value)
    {
      return this->set(this->get() + value);
    }
 
    T operator -= (T const& value)
    {
      return this->set(this->get() - value);
    }
 
    T operator *= (T const& value)
    {
      return this->set(this->get() * value);
    }
 
    T operator /= (T const& value)
    {
      return this->set(this->get() / value);
    }
 
    T operator ^= (T const& value)
    {
      return this->set(this->get() ^ value);
    }
 
    T operator %= (T const& value)
    {
      return this->set(this->get() % value);
    }
 
    T operator &= (T const& value)
    {
      return this->set(this->get() & value);
    }
 
    T operator |= (T const& value)
    {
      return this->set(this->get() | value);
    }
 
    T operator <<= (T const& value)
    {
      return this->set(this->get() << value);
    }
 
    T operator >>= (T const& value)
    {
      return this->set(this->get() >> value);
    }
 
    virtual T get() const
    {
      //
      // Use default initialization.
      //
      return T{};
    }
 
    virtual T set(T const& value)
    {
      return value;
    }
 
    T read() const
    {
      T returnValue;
 
      //
      // Check if the variable has been set or not
      // by comparing the value to the not set value
      // specified in the constructor.
      //
      if (this->isInitialized())
      {
        //
        // Get the variable from EEPROM
        // using the address this->_address.
        //
        EEPROM.get(this->_address, returnValue);
      }
      else
      {
        //
        // Return the default value.
        //
        returnValue = this->_defaultValue;
      }
 
      return returnValue;
    }
 
    void write(T const& value) const
    {
      //
      // Write the value to EEPROM using the put method. 
      // Put uses EEPROM.update() to perform the write 
      // so it will not rewrite the value if it didn't 
      // change.
      //
      EEPROM.put(this->_address, value);
 
      //
      // Write the checksum.
      //
      byte checksum = Checksum<T>::get(value);
      EEPROMUtil.updateEEPROM(this->checksumAddress(), checksum);
    }
 
    bool isInitialized() const
    {
      return (this->checksum() == this->checksumByte());
    }
 
    uint length() const
    {
      //
      // The extra byte is the checksum byte.
      //
      return this->size() + 1;
    }
 
    uint size() const
    {
      //
      // The extra byte is the checksum byte.
      //
      return sizeof(T);
    }
 
    void unset(byte unsetValue = UNSET_VALUE)
    {
      for (uint i = 0; i < this->length(); i++)
      {
        uint address = this->normalizeAddress(this->_address + i);
        EEPROMUtil.updateEEPROM(address, unsetValue);
      }
    }
 
    uint checksumAddress() const
    {
      return this->normalizeAddress(this->_address + this->length() - 1);
    }
 
    byte checksumByte() const
    {
      return EEPROM.read(this->checksumAddress());
    }
 
    byte checksum() const
    {
      return Checksum<T>::getEEPROM(this->getAddress(), sizeof(T));
    }
 
    void copyTo(byte* data, uint length) const
    {
      for (uint i = 0; i < length; i++)
      {
        uint address = this->normalizeAddress(this->_address + i);
        data[i] = EEPROM[address];
      }
    }
 
    uint getAddress() const
    {
      return this->_address;
    }
 
    uint nextAddress() const
    {
      return this->normalizeAddress(this->getAddress() + this->length());
    }
 
    T getDefaultValue() const
    {
      return this->_defaultValue;
    }
 
  protected:
    uint _address = 0;
 
    T _defaultValue;
 
    byte computeChecksum(T value);
    
    uint normalizeAddress(uint address) const
    {
      return min(address, EEPROM.length() - 1);
    }
};
#endif