int8_t STORAGE_Read_FS(uint8_t lun, uint8_t *buf, uint32_t blk_addr, uint16_t blk_len)
{
  /* USER CODE BEGIN 6 */
  uint32_t i;
  switch (lun)
  {
    case 0:
       for(i = 0; i < blk_len*STORAGE_BLK_SIZ; i += 4)
         {
             *(uint32_t*)(&buf[i]) = ((volatile uint32_t*)(FLASH_MSD_START_ADDR + blk_addr*STORAGE_BLK_SIZ))[i];
         }
      break;
    case 1:
      break;
    default:
      return USBD_FAIL;
  }
   
  return (USBD_OK);
  /* USER CODE END 6 */
}

int8_t STORAGE_Write_FS(uint8_t lun, uint8_t *buf, uint32_t blk_addr, uint16_t blk_len)
{
  /* USER CODE BEGIN 7 */

   FLASH_EraseInitTypeDef EraseInitStruct;
   uint32_t PAGEError = 0;
  uint32_t i;
  switch (lun)
  {
    case 0:   
      for(i = 0; i < blk_len*STORAGE_BLK_SIZ; i += FLASH_PAGE_SIZE)
      {
            EraseInitStruct.TypeErase   = FLASH_TYPEERASE_PAGES;
            EraseInitStruct.PageAddress = FLASH_MSD_START_ADDR + blk_addr*STORAGE_BLK_SIZ + i;
            EraseInitStruct.NbPages     = 1;
            if (HAL_FLASHEx_Erase(&EraseInitStruct, &PAGEError) != HAL_OK)
            {   
               // error
            }
      }         
     
      for(i = 0; i < blk_len*STORAGE_BLK_SIZ; i += 4)
      {
          HAL_FLASH_Program(FLASH_TYPEPROGRAM_WORD,FLASH_MSD_START_ADDR + blk_addr*STORAGE_BLK_SIZ + i , *(uint32_t*)(&buf[i]));
      }
     
      break;
    case 1:
      break;
    default:
      return USBD_FAIL;
  }
  return (USBD_OK);
  /* USER CODE END 7 */
}

#define STORAGE_BLK_NBR                  50
#define STORAGE_BLK_SIZ                  2048

int8_t STORAGE_Read_FS(uint8_t lun, uint8_t *buf, uint32_t blk_addr, uint16_t blk_len)
{
   memcpy(buf, (void *)(STORAGE_ADDRESS + STORAGE_BLK_SIZ * blk_addr), (STORAGE_BLK_SIZ * blk_len));

   return (USBD_OK);
}



int8_t STORAGE_Write_FS(uint8_t lun, uint8_t *buf, uint32_t blk_addr, uint16_t blk_len)
{
   /* USER CODE BEGIN 7 */

    ERASE_One_Page((STORAGE_ADDRESS) + (STORAGE_BLK_SIZ * blk_addr));

    WRITE_One_Page(((uint64_t *)buf), ((STORAGE_ADDRESS)+(STORAGE_BLK_SIZ * blk_addr)));

   return (USBD_OK);
   /* USER CODE END 7 */
}


void WRITE_One_Page(uint64_t *bufptr, uint32_t page_address)
{
   for(uint32_t i = 0; i < STORAGE_BLK_SIZ ; i += 8)
   {
      HAL_FLASH_Program(FLASH_PROC_PROGRAMDOUBLEWORD , (page_address + i) , *bufptr); //send 8 bytes to write
      bufptr ++; // bufptr is 64bit value - incrementation onward 8 bytes
   }
}



void ERASE_One_Page(uint32_t page_address)
{
   FLASH_EraseInitTypeDef flashErase_handle; // declare structure to erase page
   uint32_t sectorError; // if check any errors after erase here you can...

   //memset(&flashErase_handle, 0, sizeof(flashErase_handle)); // don't need every one field this structure is initialize here
   HAL_FLASH_Unlock(); //don't need it's on time unlocked in STORAGE_FileSystem_Init function

   flashErase_handle.TypeErase = FLASH_TYPEERASE_PAGES; // page type erase
   flashErase_handle.Banks = FLASH_BANK_1; //bank 1
   flashErase_handle.PageAddress = page_address; // address of page to erase
   flashErase_handle.NbPages = 1 ; // only one page to erase

   HAL_FLASHEx_Erase(&flashErase_handle, &sectorError); // Let's do ERASE ONE PAGE...

   //HAL_FLASH_Lock();
}