/**
  ******************************************************************************
  * @file    EEPROM/EEPROM_Emulation/src/eeprom.c
  * @author  MCD Application Team
  * @brief   This file provides all the EEPROM emulation firmware functions.
  ******************************************************************************
  * @attention
  *
  * <h2><center>&copy; Copyright � 2017 STMicroelectronics International N.V.
  * All rights reserved.</center></h2>
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted, provided that the following conditions are met:
  *
  * 1. Redistribution of source code must retain the above copyright notice,
  *    this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright notice,
  *    this list of conditions and the following disclaimer in the documentation
  *    and/or other materials provided with the distribution.
  * 3. Neither the name of STMicroelectronics nor the names of other
  *    contributors to this software may be used to endorse or promote products
  *    derived from this software without specific written permission.
  * 4. This software, including modifications and/or derivative works of this
  *    software, must execute solely and exclusively on microcontroller or
  *    microprocessor devices manufactured by or for STMicroelectronics.
  * 5. Redistribution and use of this software other than as permitted under
  *    this license is void and will automatically terminate your rights under
  *    this license.
  *
  * THIS SOFTWARE IS PROVIDED BY STMICROELECTRONICS AND CONTRIBUTORS "AS IS"
  * AND ANY EXPRESS, IMPLIED OR STATUTORY WARRANTIES, INCLUDING, BUT NOT
  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
  * PARTICULAR PURPOSE AND NON-INFRINGEMENT OF THIRD PARTY INTELLECTUAL PROPERTY
  * RIGHTS ARE DISCLAIMED TO THE FULLEST EXTENT PERMITTED BY LAW. IN NO EVENT
  * SHALL STMICROELECTRONICS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA,
  * OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
  * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
  * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
  * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  *
  ******************************************************************************
  */
/** @addtogroup EEPROM_Emulation
  * @{
  */

/* Includes ------------------------------------------------------------------*/
#include "eeprom_f4.h"

/* Private typedef -----------------------------------------------------------*/
/* Private define ------------------------------------------------------------*/
/* Private macro -------------------------------------------------------------*/
/* Private variables ---------------------------------------------------------*/

/* Global variable used to store variable value in read sequence */
uint16_t DataVar = 0;

/* Virtual address defined by the user: 0xFFFF value is prohibited */
extern uint16_t VirtAddVarTab[NB_OF_VAR];

/* Private function prototypes -----------------------------------------------*/
/* Private functions ---------------------------------------------------------*/
static HAL_StatusTypeDef EE_Format(void);
static uint16_t EE_FindValidPage(uint8_t Operation);
static uint16_t EE_VerifyPageFullWriteVariable(uint16_t VirtAddress, uint16_t Data);
static uint16_t EE_PageTransfer(uint16_t VirtAddress, uint16_t Data);
static uint16_t EE_VerifyPageFullyErased(uint32_t Address);

/**
  * @brief  Restore the pages to a known good state in case of page's status
  *   corruption after a power loss.
  * @param  None.
  * @retval - Flash error code: on write Flash error
  *         - FLASH_COMPLETE: on success
  */
uint16_t EE_Init(void)
{
  uint16_t PageStatus0 = 6, PageStatus1 = 6;
  uint16_t VarIdx = 0;
  uint16_t EepromStatus = 0, ReadStatus = 0;
  int16_t x = -1;
  HAL_StatusTypeDef  FlashStatus;

  FLASH_UnlockF4();

  /* Get Page0 status */
  PageStatus0 = (*(__IO uint16_t*)PAGE0_BASE_ADDRESS);
  /* Get Page1 status */
  PageStatus1 = (*(__IO uint16_t*)PAGE1_BASE_ADDRESS);

  /* Check for invalid header states and repair if necessary */
  switch (PageStatus0)
  {
    case ERASED:
      if (PageStatus1 == VALID_PAGE) /* Page0 erased, Page1 valid */
      {
          /* Erase Page0 */
        if(!EE_VerifyPageFullyErased(PAGE0_BASE_ADDRESS))
        {
          FlashStatus = FLASH_EraseSectorF4(PAGE0_ID);
          /* If erase operation was failed, a Flash error code is returned */
          if (FlashStatus != HAL_OK)
          {
            return FlashStatus;
          }
        }
      }
      else if (PageStatus1 == RECEIVE_DATA) /* Page0 erased, Page1 receive */
      {
        /* Erase Page0 */
        if(!EE_VerifyPageFullyErased(PAGE0_BASE_ADDRESS))
        {
          FlashStatus = FLASH_EraseSectorF4(PAGE1_ID);
          /* If erase operation was failed, a Flash error code is returned */
          if (FlashStatus != HAL_OK)
          {
            return FlashStatus;
          }
        }
        /* Mark Page1 as valid */
        FlashStatus = FLASH_ProgramHalfWordF4(PAGE1_BASE_ADDRESS, VALID_PAGE);
        /* If program operation was failed, a Flash error code is returned */
        if (FlashStatus != HAL_OK)
        {
          return FlashStatus;
        }
      }
      else /* First EEPROM access (Page0&1 are erased) or invalid state -> format EEPROM */
      {
        /* Erase both Page0 and Page1 and set Page0 as valid page */
        FlashStatus = EE_Format();
        /* If erase/program operation was failed, a Flash error code is returned */
        if (FlashStatus != HAL_OK)
        {
          return FlashStatus;
        }
      }
      break;

    case RECEIVE_DATA:
      if (PageStatus1 == VALID_PAGE) /* Page0 receive, Page1 valid */
      {
        /* Transfer data from Page1 to Page0 */
        for (VarIdx = 0; VarIdx < NB_OF_VAR; VarIdx++)
        {
          if (( *(__IO uint16_t*)(PAGE0_BASE_ADDRESS + 6)) == VirtAddVarTab[VarIdx])
          {
            x = VarIdx;
          }
          if (VarIdx != x)
          {
            /* Read the last variables' updates */
            ReadStatus = EE_ReadVariable(VirtAddVarTab[VarIdx], &DataVar);
            /* In case variable corresponding to the virtual address was found */
            if (ReadStatus != 0x1)
            {
              /* Transfer the variable to the Page0 */
              EepromStatus = EE_VerifyPageFullWriteVariable(VirtAddVarTab[VarIdx], DataVar);
              /* If program operation was failed, a Flash error code is returned */
              if (EepromStatus != HAL_OK)
              {
                return EepromStatus;
              }
            }
          }
        }
        /* Mark Page0 as valid */
        FlashStatus = FLASH_ProgramHalfWordF4(PAGE0_BASE_ADDRESS, VALID_PAGE);
        /* If program operation was failed, a Flash error code is returned */
        if (FlashStatus != HAL_OK)
        {
          return FlashStatus;
        }
        /* Erase Page1 */
        if(!EE_VerifyPageFullyErased(PAGE1_BASE_ADDRESS))
        {
          FlashStatus = FLASH_EraseSectorF4(PAGE1_ID);
          /* If erase operation was failed, a Flash error code is returned */
          if (FlashStatus != HAL_OK)
          {
            return FlashStatus;
          }
        }
      }
      else if (PageStatus1 == ERASED) /* Page0 receive, Page1 erased */
      {
        /* Erase Page1 */
        if(!EE_VerifyPageFullyErased(PAGE1_BASE_ADDRESS))
        {
          FlashStatus = FLASH_EraseSectorF4(PAGE1_ID);
          /* If erase operation was failed, a Flash error code is returned */
          if (FlashStatus != HAL_OK)
          {
            return FlashStatus;
          }
        }
        /* Mark Page0 as valid */
        FlashStatus = FLASH_ProgramHalfWordF4(PAGE0_BASE_ADDRESS, VALID_PAGE);
        /* If program operation was failed, a Flash error code is returned */
        if (FlashStatus != HAL_OK)
        {
          return FlashStatus;
        }
      }
      else /* Invalid state -> format eeprom */
      {
        /* Erase both Page0 and Page1 and set Page0 as valid page */
        FlashStatus = EE_Format();
        /* If erase/program operation was failed, a Flash error code is returned */
        if (FlashStatus != HAL_OK)
        {
          return FlashStatus;
        }
      }
      break;

    case VALID_PAGE:
      if (PageStatus1 == VALID_PAGE) /* Invalid state -> format eeprom */
      {
        /* Erase both Page0 and Page1 and set Page0 as valid page */
        FlashStatus = EE_Format();
        /* If erase/program operation was failed, a Flash error code is returned */
        if (FlashStatus != HAL_OK)
        {
          return FlashStatus;
        }
      }
      else if (PageStatus1 == ERASED) /* Page0 valid, Page1 erased */
      {
        /* Erase Page1 */
        if(!EE_VerifyPageFullyErased(PAGE1_BASE_ADDRESS))
        {
          FlashStatus = FLASH_EraseSectorF4(PAGE1_ID);
          /* If erase operation was failed, a Flash error code is returned */
          if (FlashStatus != HAL_OK)
          {
            return FlashStatus;
          }
        }
      }
      else /* Page0 valid, Page1 receive */
      {
        /* Transfer data from Page0 to Page1 */
        for (VarIdx = 0; VarIdx < NB_OF_VAR; VarIdx++)
        {
          if ((*(__IO uint16_t*)(PAGE1_BASE_ADDRESS + 6)) == VirtAddVarTab[VarIdx])
          {
            x = VarIdx;
          }
          if (VarIdx != x)
          {
            /* Read the last variables' updates */
            ReadStatus = EE_ReadVariable(VirtAddVarTab[VarIdx], &DataVar);
            /* In case variable corresponding to the virtual address was found */
            if (ReadStatus != 0x1)
            {
              /* Transfer the variable to the Page1 */
              EepromStatus = EE_VerifyPageFullWriteVariable(VirtAddVarTab[VarIdx], DataVar);
              /* If program operation was failed, a Flash error code is returned */
              if (EepromStatus != HAL_OK)
              {
                return EepromStatus;
              }
            }
          }
        }
        /* Mark Page1 as valid */
        FlashStatus = FLASH_ProgramHalfWordF4(PAGE1_BASE_ADDRESS, VALID_PAGE);
        /* If program operation was failed, a Flash error code is returned */
        if (FlashStatus != HAL_OK)
        {
          return FlashStatus;
        }
        /* Erase Page0 */
        if(!EE_VerifyPageFullyErased(PAGE0_BASE_ADDRESS))
        {
          FlashStatus = FLASH_EraseSectorF4(PAGE0_ID);
          /* If erase operation was failed, a Flash error code is returned */
          if (FlashStatus != HAL_OK)
          {
            return FlashStatus;
          }
        }
      }
      break;

    default:  /* Any other state -> format eeprom */
      /* Erase both Page0 and Page1 and set Page0 as valid page */
      FlashStatus = EE_Format();
      /* If erase/program operation was failed, a Flash error code is returned */
      if (FlashStatus != HAL_OK)
      {
        return FlashStatus;
      }
      break;
  }

  return HAL_OK;
}

/**
  * @brief  Verify if specified page is fully erased.
  * @param  Address: page address
  *   This parameter can be one of the following values:
  *     @arg PAGE0_BASE_ADDRESS: Page0 base address
  *     @arg PAGE1_BASE_ADDRESS: Page1 base address
  * @retval page fully erased status:
  *           - 0: if Page not erased
  *           - 1: if Page erased
  */
uint16_t EE_VerifyPageFullyErased(uint32_t Address)
{
  uint32_t ReadStatus = 1;
  uint16_t AddressValue = 0x5555;

  /* Check each active page address starting from end */
  while (Address <= PAGE0_END_ADDRESS)
  {
    /* Get the current location content to be compared with virtual address */
    AddressValue = (*(__IO uint16_t*)Address);

    /* Compare the read address with the virtual address */
    if (AddressValue != ERASED)
    {

      /* In case variable value is read, reset ReadStatus flag */
      ReadStatus = 0;

      break;
    }
    /* Next address location */
    Address = Address + 4;
  }

  /* Return ReadStatus value: (0: Page not erased, 1: Sector erased) */
  return ReadStatus;
}

/**
  * @brief  Returns the last stored variable data, if found, which correspond to
  *   the passed virtual address
  * @param  VirtAddress: Variable virtual address
  * @param  Data: Global variable contains the read variable value
  * @retval Success or error status:
  *           - 0: if variable was found
  *           - 1: if the variable was not found
  *           - NO_VALID_PAGE: if no valid page was found.
  */
uint16_t EE_ReadVariable(uint16_t VirtAddress, uint16_t* Data)
{
  uint16_t ValidPage = PAGE0;
  uint16_t AddressValue = 0x5555, ReadStatus = 1;
  uint32_t Address = EEPROM_START_ADDRESS, PageStartAddress = EEPROM_START_ADDRESS;

  /* Get active Page for read operation */
  ValidPage = EE_FindValidPage(READ_FROM_VALID_PAGE);

  /* Check if there is no valid page */
  if (ValidPage == NO_VALID_PAGE)
  {
    return  NO_VALID_PAGE;
  }

  /* Get the valid Page start Address */
  PageStartAddress = (uint32_t)(EEPROM_START_ADDRESS + (uint32_t)(ValidPage * PAGE_SIZE));

  /* Get the valid Page end Address */
  Address = (uint32_t)((EEPROM_START_ADDRESS - 2) + (uint32_t)((1 + ValidPage) * PAGE_SIZE));

  /* Check each active page address starting from end */
  while (Address > (PageStartAddress + 2))
  {
    /* Get the current location content to be compared with virtual address */
    AddressValue = (*(__IO uint16_t*)Address);

    /* Compare the read address with the virtual address */
    if (AddressValue == VirtAddress)
    {
      /* Get content of Address-2 which is variable value */
      *Data = (*(__IO uint16_t*)(Address - 2));

      /* In case variable value is read, reset ReadStatus flag */
      ReadStatus = 0;

      break;
    }
    else
    {
      /* Next address location */
      Address = Address - 4;
    }
  }

  /* Return ReadStatus value: (0: variable exist, 1: variable doesn't exist) */
  return ReadStatus;
}

/**
  * @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
  *           - PAGE_FULL: if valid page is full
  *           - NO_VALID_PAGE: if no valid page was found
  *           - Flash error code: on write Flash error
  */
uint16_t EE_WriteVariable(uint16_t VirtAddress, uint16_t Data)
{
  uint16_t Status = 0;

  /* Write the variable virtual address and value in the EEPROM */
  Status = EE_VerifyPageFullWriteVariable(VirtAddress, Data);

  /* In case the EEPROM active page is full */
  if (Status == PAGE_FULL)
  {
    /* Perform Page transfer */
    Status = EE_PageTransfer(VirtAddress, Data);
  }

  /* Return last operation status */
  return Status;
}

/**
  * @brief  Erases PAGE and PAGE1 and writes VALID_PAGE header to PAGE
  * @param  None
  * @retval Status of the last operation (Flash write or erase) done during
  *         EEPROM formating
  */
static HAL_StatusTypeDef EE_Format(void)
{
  HAL_StatusTypeDef FlashStatus = HAL_OK;

  /* Erase Page0 */
  if(!EE_VerifyPageFullyErased(PAGE0_BASE_ADDRESS))
  {
    FlashStatus = FLASH_EraseSectorF4(PAGE0_ID);
    /* If erase operation was failed, a Flash error code is returned */
    if (FlashStatus != HAL_OK)
    {
      return FlashStatus;
    }
  }
  /* Set Page0 as valid page: Write VALID_PAGE at Page0 base address */
  FlashStatus = FLASH_ProgramHalfWordF4(PAGE0_BASE_ADDRESS, VALID_PAGE);
  /* If program operation was failed, a Flash error code is returned */
  if (FlashStatus != HAL_OK)
  {
    return FlashStatus;
  }

  /* Erase Page1 */
  if(!EE_VerifyPageFullyErased(PAGE1_BASE_ADDRESS))
  {
    FlashStatus = FLASH_EraseSectorF4(PAGE1_ID);
    /* If erase operation was failed, a Flash error code is returned */
    if (FlashStatus != HAL_OK)
    {
      return FlashStatus;
    }
  }

  return HAL_OK;
}

/**
  * @brief  Find valid Page for write or read operation
  * @param  Operation: operation to achieve on the valid page.
  *   This parameter can be one of the following values:
  *     @arg READ_FROM_VALID_PAGE: read operation from valid page
  *     @arg WRITE_IN_VALID_PAGE: write operation from valid page
  * @retval Valid page number (PAGE or PAGE1) or NO_VALID_PAGE in case
  *   of no valid page was found
  */
static uint16_t EE_FindValidPage(uint8_t Operation)
{
  uint16_t PageStatus0 = 6, PageStatus1 = 6;

  /* Get Page0 actual status */
  PageStatus0 = (*(__IO uint16_t*)PAGE0_BASE_ADDRESS);

  /* Get Page1 actual status */
  PageStatus1 = (*(__IO uint16_t*)PAGE1_BASE_ADDRESS);

  /* Write or read operation */
  switch (Operation)
  {
    case WRITE_IN_VALID_PAGE:   /* ---- Write operation ---- */
      if (PageStatus1 == VALID_PAGE)
      {
        /* Page0 receiving data */
        if (PageStatus0 == RECEIVE_DATA)
        {
          return PAGE0;         /* Page0 valid */
        }
        else
        {
          return PAGE1;         /* Page1 valid */
        }
      }
      else if (PageStatus0 == VALID_PAGE)
      {
        /* Page1 receiving data */
        if (PageStatus1 == RECEIVE_DATA)
        {
          return PAGE1;         /* Page1 valid */
        }
        else
        {
          return PAGE0;         /* Page0 valid */
        }
      }
      else
      {
        return NO_VALID_PAGE;   /* No valid Page */
      }

    case READ_FROM_VALID_PAGE:  /* ---- Read operation ---- */
      if (PageStatus0 == VALID_PAGE)
      {
        return PAGE0;           /* Page0 valid */
      }
      else if (PageStatus1 == VALID_PAGE)
      {
        return PAGE1;           /* Page1 valid */
      }
      else
      {
        return NO_VALID_PAGE ;  /* No valid Page */
      }

    default:
      return PAGE0;             /* Page0 valid */
  }
}

/**
  * @brief  Verify if active page is full and Writes variable in EEPROM.
  * @param  VirtAddress: 16 bit virtual address of the variable
  * @param  Data: 16 bit data to be written as variable value
  * @retval Success or error status:
  *           - FLASH_COMPLETE: on success
  *           - PAGE_FULL: if valid page is full
  *           - NO_VALID_PAGE: if no valid page was found
  *           - Flash error code: on write Flash error
  */
static uint16_t EE_VerifyPageFullWriteVariable(uint16_t VirtAddress, uint16_t Data)
{
  HAL_StatusTypeDef FlashStatus = HAL_OK;
  uint16_t ValidPage = PAGE0;
  uint32_t Address = EEPROM_START_ADDRESS, PageEndAddress = EEPROM_START_ADDRESS+PAGE_SIZE;

  /* Get valid Page for write operation */
  ValidPage = EE_FindValidPage(WRITE_IN_VALID_PAGE);

  /* Check if there is no valid page */
  if (ValidPage == NO_VALID_PAGE)
  {
    return  NO_VALID_PAGE;
  }

  /* Get the valid Page start Address */
  Address = (uint32_t)(EEPROM_START_ADDRESS + (uint32_t)(ValidPage * PAGE_SIZE));

  /* Get the valid Page end Address */
  PageEndAddress = (uint32_t)((EEPROM_START_ADDRESS - 1) + (uint32_t)((ValidPage + 1) * PAGE_SIZE));

  /* Check each active page address starting from begining */
  while (Address < PageEndAddress)
  {
    /* Verify if Address and Address+2 contents are 0xFFFFFFFF */
    if ((*(__IO uint32_t*)Address) == 0xFFFFFFFF)
    {
      /* Set variable data */
      FlashStatus = FLASH_ProgramHalfWordF4(Address, Data);
      /* If program operation was failed, a Flash error code is returned */
      if (FlashStatus != HAL_OK)
      {
        return FlashStatus;
      }
      /* Set variable virtual address */
      FlashStatus = FLASH_ProgramHalfWordF4(Address + 2, VirtAddress);
      /* Return program operation status */
      return FlashStatus;
    }
    else
    {
      /* Next address location */
      Address = Address + 4;
    }
  }

  /* Return PAGE_FULL in case the valid page is full */
  return PAGE_FULL;
}

/**
  * @brief  Transfers last updated variables data from the full Page to
  *   an empty one.
  * @param  VirtAddress: 16 bit virtual address of the variable
  * @param  Data: 16 bit data to be written as variable value
  * @retval Success or error status:
  *           - FLASH_COMPLETE: on success
  *           - PAGE_FULL: if valid page is full
  *           - NO_VALID_PAGE: if no valid page was found
  *           - Flash error code: on write Flash error
  */
static uint16_t EE_PageTransfer(uint16_t VirtAddress, uint16_t Data)
{
  HAL_StatusTypeDef FlashStatus = HAL_OK;
  uint32_t NewPageAddress = EEPROM_START_ADDRESS;
  uint16_t OldPageId=0;
  uint16_t ValidPage = PAGE0, VarIdx = 0;
  uint16_t EepromStatus = 0, ReadStatus = 0;

  /* Get active Page for read operation */
  ValidPage = EE_FindValidPage(READ_FROM_VALID_PAGE);

  if (ValidPage == PAGE1)       /* Page1 valid */
  {
    /* New page address where variable will be moved to */
    NewPageAddress = PAGE0_BASE_ADDRESS;

    /* Old page ID where variable will be taken from */
    OldPageId = PAGE1_ID;
  }
  else if (ValidPage == PAGE0)  /* Page0 valid */
  {
    /* New page address  where variable will be moved to */
    NewPageAddress = PAGE1_BASE_ADDRESS;

    /* Old page ID where variable will be taken from */
    OldPageId = PAGE0_ID;
  }
  else
  {
    return NO_VALID_PAGE;       /* No valid Page */
  }

  /* Set the new Page status to RECEIVE_DATA status */
  FlashStatus = FLASH_ProgramHalfWordF4(NewPageAddress, RECEIVE_DATA);
  /* If program operation was failed, a Flash error code is returned */
  if (FlashStatus != HAL_OK)
  {
    return FlashStatus;
  }

  /* Write the variable passed as parameter in the new active page */
  EepromStatus = EE_VerifyPageFullWriteVariable(VirtAddress, Data);
  /* If program operation was failed, a Flash error code is returned */
  if (EepromStatus != HAL_OK)
  {
    return EepromStatus;
  }

  /* Transfer process: transfer variables from old to the new active page */
  for (VarIdx = 0; VarIdx < NB_OF_VAR; VarIdx++)
  {
    if (VirtAddVarTab[VarIdx] != VirtAddress)  /* Check each variable except the one passed as parameter */
    {
      /* Read the other last variable updates */
      ReadStatus = EE_ReadVariable(VirtAddVarTab[VarIdx], &DataVar);
      /* In case variable corresponding to the virtual address was found */
      if (ReadStatus != 0x1)
      {
        /* Transfer the variable to the new active page */
        EepromStatus = EE_VerifyPageFullWriteVariable(VirtAddVarTab[VarIdx], DataVar);
        /* If program operation was failed, a Flash error code is returned */
        if (EepromStatus != HAL_OK)
        {
          return EepromStatus;
        }
      }
    }
  }

  /* Erase the old Page: Set old Page status to ERASED status */
  FlashStatus = FLASH_EraseSectorF4(OldPageId);
  /* If erase operation was failed, a Flash error code is returned */
  if (FlashStatus != HAL_OK)
  {
    return FlashStatus;
  }

  /* Set new Page status to VALID_PAGE status */
  FlashStatus = FLASH_ProgramHalfWordF4(NewPageAddress, VALID_PAGE);
  /* If program operation was failed, a Flash error code is returned */
  if (FlashStatus != HAL_OK)
  {
    return FlashStatus;
  }

  /* Return last operation flash status */
  return FlashStatus;
}

/* flash operation */

#define EraseTimeout        ((uint32_t)0x00000FFF)
#define ProgramTimeout      ((uint32_t)0x0000001F)

#define FLASH_PSIZE_BYTE    0
#define FLASH_PSIZE_HFWORD  FLASH_CR_PSIZE_0
#define FLASH_PSIZE_WORD    FLASH_CR_PSIZE_1
#define FLASH_CR_SNB_Pos    3
#define FLASH_KEY1_F4       0x45670123
#define FLASH_KEY2_F4       0xCDEF89AB

#define ASSERT(exp) (void)((0))

static void Flash_Delay(void)
{
    __IO uint32_t i = 0;
    for(i = 0xFF; i != 0; i--) { }
}

static HAL_StatusTypeDef FLASH_GetStatus(void)
{
    if ((FLASH->SR & FLASH_SR_BSY) == FLASH_SR_BSY)
        return HAL_BUSY;

    if ((FLASH->SR & (FLASH_SR_PGSERR|FLASH_SR_PGPERR|FLASH_SR_PGAERR)) != 0)
        return HAL_ERROR;

    if ((FLASH->SR & FLASH_SR_WRPERR) != 0 )
        return HAL_ERROR;

    if ((FLASH->SR & FLASH_SR_SOP) != 0 )
        return HAL_ERROR;

    return HAL_OK;
}

static HAL_StatusTypeDef FLASH_WaitForLastOperation(uint32_t timeout)
{
    /* Check for the Flash Status */
    HAL_StatusTypeDef status = FLASH_GetStatus();
    /* Wait for a Flash operation to complete or a TIMEOUT to occur */
    while ((status == HAL_BUSY) && (timeout != 0x00))
    {
        Flash_Delay();
        status = FLASH_GetStatus();
        timeout--;
    }
    if (timeout == 0)
        status = HAL_TIMEOUT;

    return status;
}
HAL_StatusTypeDef FLASH_UnlockF4(void)
{
    FLASH->KEYR = FLASH_KEY1_F4;
    FLASH->KEYR = FLASH_KEY2_F4;
    return HAL_OK;
}

HAL_StatusTypeDef FLASH_EraseSectorF4(uint32_t sector)
{
    HAL_StatusTypeDef status = HAL_OK;
    /* Wait for last operation to be completed */
    status = FLASH_WaitForLastOperation(EraseTimeout);

    if(status == HAL_OK) {
        /* if the previous operation is completed, proceed to erase the page */
        CLEAR_BIT(FLASH->CR, FLASH_CR_PSIZE);
        FLASH->CR |= FLASH_PSIZE_WORD;
        CLEAR_BIT(FLASH->CR, FLASH_CR_SNB);
        FLASH->CR |= FLASH_CR_SER | (sector << FLASH_CR_SNB_Pos);
        FLASH->CR |= FLASH_CR_STRT;

        /* Wait for last operation to be completed */
        status = FLASH_WaitForLastOperation(EraseTimeout);
        if(status != HAL_TIMEOUT)
        {
            /* if the erase operation is completed, disable the PER Bit */
            FLASH->CR &= ~FLASH_CR_SNB;
            FLASH->CR &= ~FLASH_CR_SER;
        }

        FLASH->SR = (FLASH_SR_EOP | FLASH_SR_SOP | FLASH_SR_WRPERR);
    }
    /* Return the Erase Status */
    return status;
}

HAL_StatusTypeDef FLASH_ProgramHalfWordF4(uint32_t address, uint16_t data)
{
    HAL_StatusTypeDef status = HAL_ERROR;

    if (IS_FLASH_ADDRESS(address))
    {
        /* Wait for last operation to be completed */
        status = FLASH_WaitForLastOperation(ProgramTimeout);
        if(status == HAL_OK) {
            // set size to byte
            FLASH->CR &= ~FLASH_CR_PSIZE;
            FLASH->CR |= FLASH_PSIZE_HFWORD;
            FLASH->CR |= FLASH_CR_PG;

            *(__IO uint16_t*)address = data;
            /* Wait for last operation to be completed */
            status = FLASH_WaitForLastOperation(ProgramTimeout);
            if(status != HAL_TIMEOUT)
            {
                /* if the program operation is completed, disable the PG Bit */
                FLASH->CR &= ~FLASH_CR_PG;
            }
            FLASH->SR = (FLASH_SR_EOP | FLASH_SR_SOP | FLASH_SR_PGSERR | FLASH_SR_PGPERR | FLASH_SR_PGAERR | FLASH_SR_WRPERR);
        }
    }
    return status;
}

/**
  * @}
  */

/******************* (C) COPYRIGHT 2017 STMicroelectronics *****END OF FILE****/