text: /**
   * Marlin 3D Printer Firmware
   * Copyright (c) 2020 MarlinFirmware [https://github.com/MarlinFirmware/Marlin]
   *
   * Based on Sprinter and grbl.
   * Copyright (c) 2011 Camiel Gubbels / Erik van der Zalm
   *
   * This program is free software: you can redistribute it and/or modify
   * it under the terms of the GNU General Public License as published by
   * the Free Software Foundation, either version 3 of the License, or
   * (at your option) any later version.
   *
   * This program 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 General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program.  If not, see <http://www.gnu.org/licenses/>.
   *
   */
  
  /**
   * Implementation of EEPROM settings in SD Card
   */
  
  #if defined(ARDUINO_ARCH_STM32) && !defined(STM32GENERIC)
  
  #include "../../inc/MarlinConfig.h"
  
  #if ENABLED(EEPROM_SETTINGS) && NONE(FLASH_EEPROM_EMULATION, SRAM_EEPROM_EMULATION, SPI_EEPROM, I2C_EEPROM)
  
  #include "../shared/persistent_store_api.h"
  
  #ifndef E2END
    #define E2END 0xFFF // 4KB
  #endif
  #define HAL_EEPROM_SIZE int(E2END + 1)
  
  #define _ALIGN(x) __attribute__ ((aligned(x)))
  static char _ALIGN(4) HAL_eeprom_data[HAL_EEPROM_SIZE];
  
  #if ENABLED(SDSUPPORT)
  
    #include "../../sd/cardreader.h"
  
    #define EEPROM_FILENAME "eeprom.dat"
  
    bool PersistentStore::access_start() {
      if (!card.isMounted()) return false;
  
      SdFile file, root = card.getroot();
      if (!file.open(&root, EEPROM_FILENAME, O_RDONLY))
        return true;
  
      int bytes_read = file.read(HAL_eeprom_data, HAL_EEPROM_SIZE);
      if (bytes_read < 0) return false;
      for (; bytes_read < HAL_EEPROM_SIZE; bytes_read++)
        HAL_eeprom_data[bytes_read] = 0xFF;
      file.close();
      return true;
    }
  
    bool PersistentStore::access_finish() {
      if (!card.isMounted()) return false;
  
      SdFile file, root = card.getroot();
      int bytes_written = 0;
      if (file.open(&root, EEPROM_FILENAME, O_CREAT | O_WRITE | O_TRUNC)) {
        bytes_written = file.write(HAL_eeprom_data, HAL_EEPROM_SIZE);
        file.close();
      }
      return (bytes_written == HAL_EEPROM_SIZE);
    }
  
  #else // !SDSUPPORT
  
    #error "Please define an EEPROM, a SDCARD or disable EEPROM_SETTINGS."
  
  #endif // !SDSUPPORT
  
  bool PersistentStore::write_data(int &pos, const uint8_t *value, size_t size, uint16_t *crc) {
    for (size_t i = 0; i < size; i++)
      HAL_eeprom_data[pos + i] = value[i];
    crc16(crc, value, size);
    pos += size;
    return false;
  }
  
  bool PersistentStore::read_data(int &pos, uint8_t* value, const size_t size, uint16_t *crc, const bool writing/*=true*/) {
    for (size_t i = 0; i < size; i++) {
      uint8_t c = HAL_eeprom_data[pos + i];
      if (writing) value[i] = c;
      crc16(crc, &c, 1);
    }
    pos += size;
    return false;
  }
  
  size_t PersistentStore::capacity() { return HAL_EEPROM_SIZE; }
  
  #endif // EEPROM_SETTINGS
  #endif // STM32
  