ardupilot/libraries/AP_HAL_F4Light/EEPROM.h

#pragma once

#include "stm32f4xx_flash.h"
#include <stdio.h>

/* Page status definitions */
#define EEPROM_ERASED			((uint16_t)0xFFFF)	/* PAGE is empty */
#define EEPROM_RECEIVE_DATA		((uint16_t)0xEEEE)	/* PAGE is marked to receive data */
#define EEPROM_VALID_PAGE		((uint16_t)0xAAAA)	/* 1st PAGE containing valid data */

#define ADDRESS_MASK 0x3fff          // valid address always below it - 16K of EEPROM max
#define FLAGS_MASK   (~ADDRESS_MASK) // if this bits are set then we have partially written slot

/* Page full define */
enum {
	EEPROM_OK            = 0x00,
	EEPROM_OUT_SIZE      = 0x81,
	EEPROM_BAD_ADDRESS   = 0x82,
	EEPROM_BAD_FLASH     = 0x83,
	EEPROM_NOT_INIT      = 0x84,
	EEPROM_WRITE_FAILED  = 0x96,
	EEPROM_NO_VALID_PAGE = 0xAB
};

#define EEPROM_DEFAULT_DATA		0xFFFF

#define FLASH_CR_ERRIE ((uint32_t)0x02000000) // not in stm32f4xx.h somehow

class EEPROMClass
{
public:
        typedef void (*func_t)(uint8_t page);
        
	EEPROMClass(void);

	uint16_t init(uint32_t, uint32_t, uint32_t);

        /**
          * @brief  Erases PAGE0 and PAGE1 and writes EEPROM_VALID_PAGE / 0 header to PAGE0
          * @param  PAGE0 and PAGE1 base addresses
          * @retval _status of the last operation (Flash write or erase) done during EEPROM formating
          */
	uint16_t format(void);

        /**
          * @brief  Returns the erase counter for current page
          * @param  Data: Global variable contains the read variable value
          * @retval Success or error status:
          *                     - EEPROM_OK: if erases counter return.
          *                     - EEPROM_NO_VALID_PAGE: if no valid page was found.
          */
	uint16_t erases(uint16_t *);
        /**
          * @brief      Returns the last stored variable data, if found,
          *                     which correspond to the passed virtual address
          * @param  Address: Variable virtual address
          * @param  Data: Pointer to data variable
          * @retval Success or error status:
          *           - EEPROM_OK: if variable was found
          *           - EEPROM_BAD_ADDRESS: if the variable was not found
          *           - EEPROM_NO_VALID_PAGE: if no valid page was found.
          */
	uint16_t read (uint16_t address, uint16_t *data);
	/**
          * @brief      Returns the last stored variable data, if found,
          *                     which correspond to the passed virtual address
          * @param  Address: Variable virtual address
          * @retval Data for variable or EEPROM_DEFAULT_DATA, if any errors
         */
        inline uint16_t read (uint16_t address) { 
            uint16_t data;
            read(address, &data);
            return data;
        }
        /**
          * @brief  Writes/upadtes variable data in EEPROM.
          * @param  VirtAddress: Variable virtual address
          * @param  Data: 16 bit data to be written
          * @retval Success or error status:
          *                     - FLASH_COMPLETE: on success
          *                     - EEPROM_BAD_ADDRESS: if address = 0xFFFF
          *                     - EEPROM_PAGE_FULL: if valid page is full
          *                     - EEPROM_NO_VALID_PAGE: if no valid page was found
          *                     - EEPROM_OUT_SIZE: if no empty EEPROM variables
          *                     - Flash error code: on write Flash error
          */
	uint16_t write(uint16_t address, uint16_t data);
	/**
         * @brief  Return number of variable
         * @retval Number of variables
        */
	uint16_t count(uint16_t *data);
	inline uint16_t maxcount(void) {   return (PageSize / 4)-1; }

        static FLASH_Status write_16(uint32_t addr, uint16_t data);
        static FLASH_Status write_8(uint32_t addr, uint8_t data);
        static void FLASH_Lock_check();
        static void FLASH_Unlock_dis();
        
        static inline uint32_t read_16(uint32_t addr){
            return *(__IO uint16_t*)addr;
        }

        static inline uint32_t read_32(uint32_t addr){
            return *(__IO uint32_t*)addr;
        }

	uint16_t _CheckErasePage(uint32_t, uint16_t);
        static FLASH_Status _ErasePageByAddress(uint32_t Page_Address);

        static void FLASH_OB_WRPConfig(uint32_t OB_WRP, FunctionalState NewState);

private:
	uint32_t PageBase0; // uses 2 flash pages
	uint32_t PageBase1;
	uint32_t PageSize;
	uint16_t _status;

	uint16_t _init(void);
	uint16_t _format(void);

	FLASH_Status _ErasePage(uint32_t);

	uint16_t _CheckPage(uint32_t, uint16_t);
	uint16_t _Format(void);
	uint32_t _FindValidPage(void);
	uint16_t _GetVariablesCount(uint32_t, uint16_t);
	uint16_t _PageTransfer(uint32_t, uint32_t, uint16_t);
	uint16_t _VerifyPageFullWriteVariable(uint16_t, uint16_t);
};


extern EEPROMClass EEPROM;