/******************** (C) COPYRIGHT 2008 STMicroelectronics ********************
* File Name          : eeprom.c
* Author             : MCD Application Team
* Version            : V2.0.0
* Date               : 06/16/2008
* Description        : This file provides all the EEPROM emulation firmware functions.
********************************************************************************
* THE PRESENT FIRMWARE WHICH IS FOR GUIDANCE ONLY AIMS AT PROVIDING CUSTOMERS
* WITH CODING INFORMATION REGARDING THEIR PRODUCTS IN ORDER FOR THEM TO SAVE TIME.
* AS A RESULT, STMICROELECTRONICS SHALL NOT BE HELD LIABLE FOR ANY DIRECT,
* INDIRECT OR CONSEQUENTIAL DAMAGES WITH RESPECT TO ANY CLAIMS ARISING FROM THE
* CONTENT OF SUCH FIRMWARE AND/OR THE USE MADE BY CUSTOMERS OF THE CODING
* INFORMATION CONTAINED HEREIN IN CONNECTION WITH THEIR PRODUCTS.
*******************************************************************************/

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

/* Private typedef -----------------------------------------------------------*/
/* Private define ------------------------------------------------------------*/
/* Private macro -------------------------------------------------------------*/
/* Private variables ---------------------------------------------------------*/
#define PAGE_SIZE  (unsigned short)(0x400)  /* Page size for eeprom emulator = 1KByte */

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

/* Virtual address defined by the user: 0xFFFF value is prohibited */
extern unsigned short VirtAddVarTab[NumbOfVar];

/* Private function prototypes -----------------------------------------------*/
/* Private functions ---------------------------------------------------------*/
FLASH_Status FlashStatus;
static FLASH_Status EE_Format ( void );
static unsigned short EE_VerifyPageFullWriteVariable ( unsigned short VirtAddress, unsigned short Data );
static unsigned short EE_FindValidPage ( char Operation );
static unsigned short EE_PageTransfer ( unsigned short VirtAddress, unsigned short Data );

/*******************************************************************************
* Function Name  : EE_Init
* Description    : Restore the pages to a known good state in case of pages'
*                  status corruption after a power loss.
* Input          : None.
* Output         : None.
* Return         : - Flash error code: on write Flash error
*                  - FLASH_COMPLETE: on success
*******************************************************************************/
unsigned short EE_Init ( void )
{
    unsigned short PageStatus0 = 6, PageStatus1 = 6;
    unsigned short VarIdx = 0;
    unsigned short EepromStatus = 0, ReadStatus = 0;
    short x = -1;
    unsigned short  FlashStatus;

    /* Get Page0 status */
    PageStatus0 = ( * ( vu16* ) PAGE0_BASE_ADDRESS );
    /* Get Page1 status */
    PageStatus1 = ( * ( vu16* ) 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 */
            FlashStatus = FLASH_ErasePage ( PAGE0_BASE_ADDRESS );

            /* If erase operation was failed, a Flash error code is returned */
            if ( FlashStatus != FLASH_COMPLETE )
            {
                return FlashStatus;
            }
        }
        else if ( PageStatus1 == RECEIVE_DATA ) /* Page0 erased, Page1 receive */
        {
            /* Erase Page0 */
            FlashStatus = FLASH_ErasePage ( PAGE0_BASE_ADDRESS );

            /* If erase operation was failed, a Flash error code is returned */
            if ( FlashStatus != FLASH_COMPLETE )
            {
                return FlashStatus;
            }

            /* Mark Page1 as valid */
            FlashStatus = FLASH_ProgramHalfWord ( PAGE1_BASE_ADDRESS, VALID_PAGE );

            /* If program operation was failed, a Flash error code is returned */
            if ( FlashStatus != FLASH_COMPLETE )
            {
                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 != FLASH_COMPLETE )
            {
                return FlashStatus;
            }
        }

        break;

    case RECEIVE_DATA:
        if ( PageStatus1 == VALID_PAGE ) /* Page0 receive, Page1 valid */
        {
            /* Transfer data from Page1 to Page0 */
            for ( VarIdx = 0; VarIdx < NumbOfVar; VarIdx++ )
            {
                if ( ( * ( vu16* ) ( 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 != FLASH_COMPLETE )
                        {
                            return EepromStatus;
                        }
                    }
                }
            }

            /* Mark Page0 as valid */
            FlashStatus = FLASH_ProgramHalfWord ( PAGE0_BASE_ADDRESS, VALID_PAGE );

            /* If program operation was failed, a Flash error code is returned */
            if ( FlashStatus != FLASH_COMPLETE )
            {
                return FlashStatus;
            }

            /* Erase Page1 */
            FlashStatus = FLASH_ErasePage ( PAGE1_BASE_ADDRESS );

            /* If erase operation was failed, a Flash error code is returned */
            if ( FlashStatus != FLASH_COMPLETE )
            {
                return FlashStatus;
            }
        }
        else if ( PageStatus1 == ERASED ) /* Page0 receive, Page1 erased */
        {
            /* Erase Page1 */
            FlashStatus = FLASH_ErasePage ( PAGE1_BASE_ADDRESS );

            /* If erase operation was failed, a Flash error code is returned */
            if ( FlashStatus != FLASH_COMPLETE )
            {
                return FlashStatus;
            }

            /* Mark Page0 as valid */
            FlashStatus = FLASH_ProgramHalfWord ( PAGE0_BASE_ADDRESS, VALID_PAGE );

            /* If program operation was failed, a Flash error code is returned */
            if ( FlashStatus != FLASH_COMPLETE )
            {
                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 != FLASH_COMPLETE )
            {
                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 != FLASH_COMPLETE )
            {
                return FlashStatus;
            }
        }
        else if ( PageStatus1 == ERASED ) /* Page0 valid, Page1 erased */
        {
            /* Erase Page1 */
            FlashStatus = FLASH_ErasePage ( PAGE1_BASE_ADDRESS );

            /* If erase operation was failed, a Flash error code is returned */
            if ( FlashStatus != FLASH_COMPLETE )
            {
                return FlashStatus;
            }
        }
        else /* Page0 valid, Page1 receive */
        {
            /* Transfer data from Page0 to Page1 */
            for ( VarIdx = 0; VarIdx < NumbOfVar; VarIdx++ )
            {
                if ( ( * ( vu16* ) ( 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 != FLASH_COMPLETE )
                        {
                            return EepromStatus;
                        }
                    }
                }
            }

            /* Mark Page1 as valid */
            FlashStatus = FLASH_ProgramHalfWord ( PAGE1_BASE_ADDRESS, VALID_PAGE );

            /* If program operation was failed, a Flash error code is returned */
            if ( FlashStatus != FLASH_COMPLETE )
            {
                return FlashStatus;
            }

            /* Erase Page0 */
            FlashStatus = FLASH_ErasePage ( PAGE0_BASE_ADDRESS );

            /* If erase operation was failed, a Flash error code is returned */
            if ( FlashStatus != FLASH_COMPLETE )
            {
                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 != FLASH_COMPLETE )
        {
            return FlashStatus;
        }

        break;
    }

    return FLASH_COMPLETE;
}

/*******************************************************************************
* Function Name  : EE_ReadVariable
* Description    : Returns the last stored variable data, if found, which
*                  correspond to the passed virtual address
* Input          : - VirtAddress: Variable virtual address
*                  - Data: Global variable contains the read variable value
* Output         : None
* Return         : - 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.
*******************************************************************************/
unsigned short EE_ReadVariable ( unsigned short VirtAddress, unsigned short* Data )
{
    unsigned short ValidPage = PAGE0;
    unsigned short AddressValue = 0x5555, ReadStatus = 1;
    unsigned int Address, PageStartAddress;

    /* 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 = ( unsigned int ) ( EEPROM_START_ADDRESS + ( unsigned int ) ( ValidPage * PAGE_SIZE ) );

    /* Get the valid Page end Address */
    Address = ( unsigned int ) ( ( EEPROM_START_ADDRESS - 2 ) + ( unsigned int ) ( ( 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 = ( * ( vu16* ) Address );

        /* Compare the read address with the virtual address */
        if ( AddressValue == VirtAddress )
        {
            /* Get content of Address-2 which is variable value */
            *Data = ( * ( vu16* ) ( 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;
}

/*******************************************************************************
* Function Name  : EE_WriteVariable
* Description    : Writes/upadtes variable data in EEPROM.
* Input          : - VirtAddress: Variable virtual address
*                  - Data: 16 bit data to be written
* Output         : None
* Return         : - 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
*******************************************************************************/
unsigned short EE_WriteVariable ( unsigned short VirtAddress, unsigned short Data )
{
    unsigned short 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;
}

/*******************************************************************************
* Function Name  : EE_Format
* Description    : Erases PAGE0 and PAGE1 and writes VALID_PAGE header to PAGE0
* Input          : None
* Output         : None
* Return         : Status of the last operation (Flash write or erase) done during
*                  EEPROM formating
*******************************************************************************/
static FLASH_Status EE_Format ( void )
{
    FLASH_Status FlashStatus = FLASH_COMPLETE;

    /* Erase Page0 */
    FlashStatus = FLASH_ErasePage ( PAGE0_BASE_ADDRESS );

    /* If erase operation was failed, a Flash error code is returned */
    if ( FlashStatus != FLASH_COMPLETE )
    {
        return FlashStatus;
    }

    /* Set Page0 as valid page: Write VALID_PAGE at Page0 base address */
    FlashStatus = FLASH_ProgramHalfWord ( PAGE0_BASE_ADDRESS, VALID_PAGE );

    /* If program operation was failed, a Flash error code is returned */
    if ( FlashStatus != FLASH_COMPLETE )
    {
        return FlashStatus;
    }

    /* Erase Page1 */
    FlashStatus = FLASH_ErasePage ( PAGE1_BASE_ADDRESS );

    /* Return Page1 erase operation status */
    return FlashStatus;
}

/*******************************************************************************
* Function Name  : EE_FindValidPage
* Description    : Find valid Page for write or read operation
* Input          : - Operation: operation to achieve on the valid page:
*                      - READ_FROM_VALID_PAGE: read operation from valid page
*                      - WRITE_IN_VALID_PAGE: write operation from valid page
* Output         : None
* Return         : Valid page number (PAGE0 or PAGE1) or NO_VALID_PAGE in case
*                  of no valid page was found
*******************************************************************************/
static unsigned short EE_FindValidPage ( char Operation )
{
    unsigned short PageStatus0 = 6, PageStatus1 = 6;

    /* Get Page0 actual status */
    PageStatus0 = ( * ( vu16* ) PAGE0_BASE_ADDRESS );

    /* Get Page1 actual status */
    PageStatus1 = ( * ( vu16* ) 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 */
    }
}

/*******************************************************************************
* Function Name  : EE_VerifyPageFullWriteVariable
* Description    : Verify if active page is full and Writes variable in EEPROM.
* Input          : - VirtAddress: 16 bit virtual address of the variable
*                  - Data: 16 bit data to be written as variable value
* Output         : None
* Return         : - 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 unsigned short EE_VerifyPageFullWriteVariable ( unsigned short VirtAddress, unsigned short Data )
{
    FLASH_Status FlashStatus = FLASH_COMPLETE;
    unsigned short ValidPage = PAGE0;
    unsigned int Address, PageEndAddress;

    /* 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 = ( unsigned int ) ( EEPROM_START_ADDRESS + ( unsigned int ) ( ValidPage * PAGE_SIZE ) );

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

    /* Check each active page address starting from begining */
    while ( Address < PageEndAddress )
    {
        /* Verify if Address and Address+2 contents are 0xFFFFFFFF */
        if ( ( * ( vu32* ) Address ) == 0xFFFFFFFF )
        {
            /* Set variable data */
            FlashStatus = FLASH_ProgramHalfWord ( Address, Data );

            /* If program operation was failed, a Flash error code is returned */
            if ( FlashStatus != FLASH_COMPLETE )
            {
                return FlashStatus;
            }

            /* Set variable virtual address */
            FlashStatus = FLASH_ProgramHalfWord ( 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;
}

/*******************************************************************************
* Function Name  : EE_PageTransfer
* Description    : Transfers last updated variables data from the full Page to
*                  an empty one.
* Input          : - VirtAddress: 16 bit virtual address of the variable
*                  - Data: 16 bit data to be written as variable value
* Output         : None
* Return         : - 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 unsigned short EE_PageTransfer ( unsigned short VirtAddress, unsigned short Data )
{
    FLASH_Status FlashStatus = FLASH_COMPLETE;
    unsigned int NewPageAddress, OldPageAddress;
    unsigned short ValidPage = PAGE0, VarIdx = 0;
    unsigned short 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 address where variable will be taken from */
        OldPageAddress = PAGE1_BASE_ADDRESS;
    }
    else if ( ValidPage == PAGE0 ) /* Page0 valid */
    {
        /* New page address where variable will be moved to */
        NewPageAddress = PAGE1_BASE_ADDRESS;

        /* Old page address where variable will be taken from */
        OldPageAddress = PAGE0_BASE_ADDRESS;
    }
    else
    {
        return NO_VALID_PAGE;       /* No valid Page */
    }

    /* Set the new Page status to RECEIVE_DATA status */
    FlashStatus = FLASH_ProgramHalfWord ( NewPageAddress, RECEIVE_DATA );

    /* If program operation was failed, a Flash error code is returned */
    if ( FlashStatus != FLASH_COMPLETE )
    {
        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 != FLASH_COMPLETE )
    {
        return EepromStatus;
    }

    /* Transfer process: transfer variables from old to the new active page */
    for ( VarIdx = 0; VarIdx < NumbOfVar; 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 != FLASH_COMPLETE )
                {
                    return EepromStatus;
                }
            }
        }
    }

    /* Erase the old Page: Set old Page status to ERASED status */
    FlashStatus = FLASH_ErasePage ( OldPageAddress );

    /* If erase operation was failed, a Flash error code is returned */
    if ( FlashStatus != FLASH_COMPLETE )
    {
        return FlashStatus;
    }

    /* Set new Page status to VALID_PAGE status */
    FlashStatus = FLASH_ProgramHalfWord ( NewPageAddress, VALID_PAGE );

    /* If program operation was failed, a Flash error code is returned */
    if ( FlashStatus != FLASH_COMPLETE )
    {
        return FlashStatus;
    }

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

/*******************************************************************************
* Function Name  : EE_XX
* Description    : Force the complete reset of the entire space of eeprom
*                  saves.
* Input          :none
** Output        : None
* Return         : None
*******************************************************************************/
void EE_XX ( void )
{
    __disable_interrupt();
    FlashStatus = EE_Format();
    __enable_interrupt();
}