/****************************************************************************************
|  Description: bootloader file system interface source file
|    File Name: file.c
|
|----------------------------------------------------------------------------------------
|                          C O P Y R I G H T
|----------------------------------------------------------------------------------------
|   Copyright (c) 2013  by Feaser    http://www.feaser.com    All rights reserved
|
|----------------------------------------------------------------------------------------
|                            L I C E N S E
|----------------------------------------------------------------------------------------
| This file is part of OpenBLT. OpenBLT 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.
|
| OpenBLT 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 OpenBLT.
| If not, see <http://www.gnu.org/licenses/>.
|
| A special exception to the GPL is included to allow you to distribute a combined work 
| that includes OpenBLT without being obliged to provide the source code for any 
| proprietary components. The exception text is included at the bottom of the license
| file <license.html>.
| 
****************************************************************************************/

/****************************************************************************************
* Include files
****************************************************************************************/
#include "boot.h"                                     /* bootloader generic header     */
#include <string.h>                                   /* for strcpy etc.               */
#include <ctype.h>                                    /* for toupper() etc.            */


#if (BOOT_FILE_SYS_ENABLE > 0)
/****************************************************************************************
* Defines
****************************************************************************************/
/* array size configurators */
#define MAX_CHARS_PER_LINE                  (256)
#define MAX_DATA_BYTES_PER_LINE             (MAX_CHARS_PER_LINE/2)
/* error codes */
#define ERROR_SREC_INVALID_CHECKSUM         (-1)


/****************************************************************************************
* Type definitions
****************************************************************************************/
typedef enum 
{ 
  FIRMWARE_UPDATE_STATE_IDLE,                    /* idle state                         */
  FIRMWARE_UPDATE_STATE_ERASING,                 /* erasing state                      */
  FIRMWARE_UPDATE_STATE_PROGRAMMING              /* programming state                  */
} tFirmwareUpdateState;                          /* state identifier type              */

typedef enum
{
  LINE_TYPE_S1,                                  /* 16-bit address line                */
  LINE_TYPE_S2,                                  /* 24-bit address line                */
  LINE_TYPE_S3,                                  /* 32-bit address line                */
  LINE_TYPE_UNSUPPORTED                          /* unsupported line                   */
} tSrecLineType;                                 /* S-Record line type                 */

typedef struct 
{
  blt_addr   start_address;                      /* erase start address                */
  blt_int32u total_size;                         /* total number of bytes to erase     */
} tFileEraseInfo;                                /* erase info structure               */

typedef struct 
{
  FATFS fs;                                      /* file system object for mouting     */
  FIL   file;                                    /* file object for firmware file      */
} tFatFsObjects;                                 /* grouped FATFS objects              */

typedef struct
{
  blt_char  line[MAX_CHARS_PER_LINE];            /* string buffer for the line chars   */
  blt_int8u data[MAX_DATA_BYTES_PER_LINE];       /* array for S1, S2 or S3 data bytes  */
  blt_addr  address;                             /* address found on S1, S2 or S3 line */
} tSrecLineParseObject;


/****************************************************************************************
* Function prototypes
****************************************************************************************/
static tSrecLineType SrecGetLineType(const blt_char *line);
static blt_bool      SrecVerifyChecksum(const blt_char *line);
static blt_int16s    SrecParseLine(const blt_char *line, blt_addr *address, blt_int8u *data);
#if (BOOT_FILE_LOGGING_ENABLE > 0)
static blt_char      FileLibByteNibbleToChar(blt_int8u nibble);
static blt_char     *FileLibByteToHexString(blt_int8u byte_val, blt_char *destination);
static blt_char     *FileLibLongToIntString(blt_int32u long_val, blt_char *destination);
#endif
static blt_int8u     FileLibHexStringToByte(const blt_char *hexstring);


/****************************************************************************************
* Hook functions
****************************************************************************************/
extern blt_bool        FileIsFirmwareUpdateRequestedHook(void);
extern const blt_char *FileGetFirmwareFilenameHook(void);
extern void            FileFirmwareUpdateStartedHook(void);
extern void            FileFirmwareUpdateCompletedHook(void);
extern void            FileFirmwareUpdateErrorHook(blt_int8u error_code);
extern void            FileFirmwareUpdateLogHook(blt_char *info_string);


/****************************************************************************************
* Local data declarations
****************************************************************************************/
static tFirmwareUpdateState firmwareUpdateState;
static tFatFsObjects        fatFsObjects;
static tSrecLineParseObject lineParseObject;
static tFileEraseInfo       eraseInfo;
#if (BOOT_FILE_LOGGING_ENABLE > 0)
static blt_char             loggingStr[64];
#endif


/****************************************************************************************
** NAME:           FileInit
** PARAMETER:      none
** RETURN VALUE:   none
** DESCRIPTION:    Initializes the file system interface module. The initial firmware
**                 update state is set to idle and the file system is mounted as 
**                 logical disk 0.
**
****************************************************************************************/
void FileInit(void)
{
  FRESULT fresult;
    
  /* set the initial state */
  firmwareUpdateState = FIRMWARE_UPDATE_STATE_IDLE;
  /* mount the file system, using logical disk 0 */
  fresult = f_mount(0, &fatFsObjects.fs);
  /* mounting does not access the disk and should succeed unless misconfigured */
  ASSERT_RT(fresult == FR_OK);
} /*** end of FileInit ***/


/****************************************************************************************
** NAME:           FileIsIdle
** PARAMETER:      none
** RETURN VALUE:   BLT_TRUE when in idle state, BLT_FALSE otherwise. 
** DESCRIPTION:    This function checks if a firmware update through the locally attached
**                 storage is in progress or not (idle).
**
****************************************************************************************/
blt_bool FileIsIdle(void)
{
  if (firmwareUpdateState == FIRMWARE_UPDATE_STATE_IDLE)
  {
    return BLT_TRUE;
  }
  return BLT_FALSE;
} /*** end of FileIsIdle ***/


/****************************************************************************************
** NAME:           FileTask
** PARAMETER:      none
** RETURN VALUE:   none
** DESCRIPTION:    File system task function for managing the firmware updates from
**                 locally attached storage.
**
****************************************************************************************/
void FileTask(void)
{
  blt_int16s  parse_result;
  blt_char   *read_line_ptr;
  
  /* ------------------------------- idle -------------------------------------------- */
  if (firmwareUpdateState == FIRMWARE_UPDATE_STATE_IDLE)
  {
    #if (BOOT_COM_ENABLE > 0)
    /* make sure that there is no connection with a remote host to prevent two firmware
     * updates happening at the same time
     */
    if (ComIsConnected() == BLT_TRUE)
    {
      return;
    }
    #endif
    /* check if a firmware update is requested */
    if (FileIsFirmwareUpdateRequestedHook() == BLT_TRUE)
    {
      #if (BOOT_FILE_STARTED_HOOK_ENABLE > 0)
      /* inform application about update started event via hook function */
      FileFirmwareUpdateStartedHook();
      #endif
      #if (BOOT_FILE_LOGGING_ENABLE > 0)
      FileFirmwareUpdateLogHook("Firmware update request detected\n\r");
      FileFirmwareUpdateLogHook("Opening firmware file for reading...");
      #endif
      /* attempt to obtain a file object for the firmware file */
      if (f_open(&fatFsObjects.file, FileGetFirmwareFilenameHook(), FA_OPEN_EXISTING | FA_READ) != FR_OK)
      {
        /* can't open file */
        #if (BOOT_FILE_LOGGING_ENABLE > 0)
        FileFirmwareUpdateLogHook("ERROR\n\r");
        #endif
        #if (BOOT_FILE_ERROR_HOOK_ENABLE > 0)
        FileFirmwareUpdateErrorHook(FILE_ERROR_CANNOT_OPEN_FIRMWARE_FILE);
        #endif        
        /* nothing left to do now */
        return;
      }
      #if (BOOT_FILE_LOGGING_ENABLE > 0)
      FileFirmwareUpdateLogHook("OK\n\r");
      FileFirmwareUpdateLogHook("Starting the programming sequence\n\r");
      FileFirmwareUpdateLogHook("Parsing firmware file to obtain erase size...");
      #endif
      /* prepare data objects for the erasing state */
      eraseInfo.start_address = 0;
      eraseInfo.total_size = 0;
      /* transition from idle to erasing state */
      firmwareUpdateState = FIRMWARE_UPDATE_STATE_ERASING;
    }
  }
  /* ------------------------------- erasing ----------------------------------------- */
  else if (firmwareUpdateState == FIRMWARE_UPDATE_STATE_ERASING)
  {
    /* read a line from the file */
    read_line_ptr = f_gets(lineParseObject.line, sizeof(lineParseObject.line), &fatFsObjects.file);
    /* check if an error occurred */
    if (f_error(&fatFsObjects.file) > 0)
    {
      #if (BOOT_FILE_LOGGING_ENABLE > 0)
      FileFirmwareUpdateLogHook("ERROR\n\r");
      #endif
      #if (BOOT_FILE_ERROR_HOOK_ENABLE > 0)
      FileFirmwareUpdateErrorHook(FILE_ERROR_CANNOT_READ_FROM_FILE);
      #endif       
      /* close the file */
      f_close(&fatFsObjects.file);
      /* cannot continue with firmware update so go back to idle state */
      firmwareUpdateState = FIRMWARE_UPDATE_STATE_IDLE;
      return;
    }
    /* parse the S-Record line without copying the data values if the line is not empty */
    if (read_line_ptr != BLT_NULL)
    {
      parse_result = SrecParseLine(lineParseObject.line, &lineParseObject.address, BLT_NULL);
      /* check parsing result */
      if (parse_result == ERROR_SREC_INVALID_CHECKSUM)
      {
        #if (BOOT_FILE_LOGGING_ENABLE > 0)
        FileFirmwareUpdateLogHook("ERROR\n\r");
        #endif
        #if (BOOT_FILE_ERROR_HOOK_ENABLE > 0)
        FileFirmwareUpdateErrorHook(FILE_ERROR_INVALID_CHECKSUM_IN_FILE);
        #endif       
        /* close the file */
        f_close(&fatFsObjects.file);
        /* cannot continue with firmware update so go back to idle state */
        firmwareUpdateState = FIRMWARE_UPDATE_STATE_IDLE;
        return;
      }
    }
    /* only process parsing results if the line contained address/data info */
    if (parse_result > 0)
    {
      /* is this the first address/data info we encountered? */
      if (eraseInfo.total_size == 0)
      {
        /* store the start_address and byte count */
        eraseInfo.start_address = lineParseObject.address;
        eraseInfo.total_size = parse_result;
      }
      else
      {
        /* update the start_address and byte count */
        if (lineParseObject.address < eraseInfo.start_address)
        {
          eraseInfo.start_address = lineParseObject.address;
        }
        eraseInfo.total_size += parse_result;
      }
    }
    /* check if the end of the file was reached */
    if (f_eof(&fatFsObjects.file) > 0)
    {
      /* rewind the file in preparation for the programming state */
      if (f_lseek(&fatFsObjects.file, 0) != FR_OK)
      {
        #if (BOOT_FILE_LOGGING_ENABLE > 0)
        FileFirmwareUpdateLogHook("ERROR\n\r");
        #endif
        #if (BOOT_FILE_ERROR_HOOK_ENABLE > 0)
        FileFirmwareUpdateErrorHook(FILE_ERROR_REWINDING_FILE_READ_POINTER);
        #endif       
        /* close the file */
        f_close(&fatFsObjects.file);
        /* cannot continue with firmware update so go back to idle state */
        firmwareUpdateState = FIRMWARE_UPDATE_STATE_IDLE;
        return;
      }
      #if (BOOT_FILE_LOGGING_ENABLE > 0)
      FileFirmwareUpdateLogHook("OK\n\r");
      FileFirmwareUpdateLogHook("Erasing ");
      /* convert size to string  */
      FileLibLongToIntString(eraseInfo.total_size, loggingStr);
      FileFirmwareUpdateLogHook(loggingStr);
      FileFirmwareUpdateLogHook(" bytes from memory at 0x");
      /* convert address to hex-string  */
      FileLibByteToHexString((blt_int8u)(eraseInfo.start_address >> 24), &loggingStr[0]);
      FileLibByteToHexString((blt_int8u)(eraseInfo.start_address >> 16), &loggingStr[2]);
      FileLibByteToHexString((blt_int8u)(eraseInfo.start_address >> 8), &loggingStr[4]);
      FileLibByteToHexString((blt_int8u)eraseInfo.start_address, &loggingStr[6]);
      FileFirmwareUpdateLogHook(loggingStr);
      FileFirmwareUpdateLogHook("...");
      #endif
      /* still here so we are ready to perform the memory erase operation */
      if (NvmErase(eraseInfo.start_address, eraseInfo.total_size) == BLT_FALSE)
      {
        #if (BOOT_FILE_LOGGING_ENABLE > 0)
        FileFirmwareUpdateLogHook("ERROR\n\r");
        #endif
        #if (BOOT_FILE_ERROR_HOOK_ENABLE > 0)
        FileFirmwareUpdateErrorHook(FILE_ERROR_CANNOT_ERASE_MEMORY);
        #endif       
        /* close the file */
        f_close(&fatFsObjects.file);
        /* cannot continue with firmware update so go back to idle state */
        firmwareUpdateState = FIRMWARE_UPDATE_STATE_IDLE;
        return;
      }
      #if (BOOT_FILE_LOGGING_ENABLE > 0)
      FileFirmwareUpdateLogHook("OK\n\r");
      #endif
      /* all okay, then go to programming state */
      firmwareUpdateState = FIRMWARE_UPDATE_STATE_PROGRAMMING;
    }
  }
  /* ------------------------------- programming ------------------------------------- */
  else if (firmwareUpdateState == FIRMWARE_UPDATE_STATE_PROGRAMMING)
  {
    /* read a line from the file */
    read_line_ptr = f_gets(lineParseObject.line, sizeof(lineParseObject.line), &fatFsObjects.file);
    /* check if an error occurred */
    if (f_error(&fatFsObjects.file) > 0)
    {
      #if (BOOT_FILE_LOGGING_ENABLE > 0)
      FileFirmwareUpdateLogHook("Reading line from file...ERROR\n\r");
      #endif
      #if (BOOT_FILE_ERROR_HOOK_ENABLE > 0)
      FileFirmwareUpdateErrorHook(FILE_ERROR_CANNOT_READ_FROM_FILE);
      #endif       
      /* close the file */
      f_close(&fatFsObjects.file);
      /* cannot continue with firmware update so go back to idle state */
      firmwareUpdateState = FIRMWARE_UPDATE_STATE_IDLE;
      return;
    }
    /* parse the S-Record line if the line is not empty */
    if (read_line_ptr != BLT_NULL)
    {
      parse_result = SrecParseLine(lineParseObject.line, &lineParseObject.address, lineParseObject.data);
      /* check parsing result */
      if (parse_result == ERROR_SREC_INVALID_CHECKSUM)
      {
        #if (BOOT_FILE_LOGGING_ENABLE > 0)
        FileFirmwareUpdateLogHook("Invalid checksum found...ERROR\n\r");
        #endif
        #if (BOOT_FILE_ERROR_HOOK_ENABLE > 0)
        FileFirmwareUpdateErrorHook(FILE_ERROR_INVALID_CHECKSUM_IN_FILE);
        #endif       
        /* close the file */
        f_close(&fatFsObjects.file);
        /* cannot continue with firmware update so go back to idle state */
        firmwareUpdateState = FIRMWARE_UPDATE_STATE_IDLE;
        return;
      }
    }
    /* only process parsing results if the line contained address/data info */
    if (parse_result > 0)
    {
      #if (BOOT_FILE_LOGGING_ENABLE > 0)
      FileFirmwareUpdateLogHook("Programming ");
      /* convert size to string  */
      FileLibLongToIntString(parse_result, loggingStr);
      FileFirmwareUpdateLogHook(loggingStr);
      FileFirmwareUpdateLogHook(" bytes to memory at 0x");
      /* convert address to hex-string  */
      FileLibByteToHexString((blt_int8u)(lineParseObject.address >> 24), &loggingStr[0]);
      FileLibByteToHexString((blt_int8u)(lineParseObject.address >> 16), &loggingStr[2]);
      FileLibByteToHexString((blt_int8u)(lineParseObject.address >> 8), &loggingStr[4]);
      FileLibByteToHexString((blt_int8u)lineParseObject.address, &loggingStr[6]);
      FileFirmwareUpdateLogHook(loggingStr);
      FileFirmwareUpdateLogHook("...");
      #endif
      /* program the data */
      if (NvmWrite(lineParseObject.address, parse_result, lineParseObject.data) == BLT_FALSE)
      {
        #if (BOOT_FILE_LOGGING_ENABLE > 0)
        FileFirmwareUpdateLogHook("ERROR\n\r");
        #endif
        #if (BOOT_FILE_ERROR_HOOK_ENABLE > 0)
        FileFirmwareUpdateErrorHook(FILE_ERROR_CANNOT_PROGRAM_MEMORY);
        #endif       
        /* close the file */
        f_close(&fatFsObjects.file);
        /* cannot continue with firmware update so go back to idle state */
        firmwareUpdateState = FIRMWARE_UPDATE_STATE_IDLE;
        return;
      }
      #if (BOOT_FILE_LOGGING_ENABLE > 0)
      FileFirmwareUpdateLogHook("OK\n\r");
      #endif
    }
    /* check if the end of the file was reached */
    if (f_eof(&fatFsObjects.file) > 0)
    {
      #if (BOOT_FILE_LOGGING_ENABLE > 0)
      FileFirmwareUpdateLogHook("Writing program checksum...");
      #endif
      /* finish the programming by writing the checksum */
      if (NvmDone() == BLT_FALSE)
      {
        #if (BOOT_FILE_LOGGING_ENABLE > 0)
        FileFirmwareUpdateLogHook("ERROR\n\r");
        #endif
        #if (BOOT_FILE_ERROR_HOOK_ENABLE > 0)
        FileFirmwareUpdateErrorHook(FILE_ERROR_CANNOT_WRITE_CHECKSUM);
        #endif       
        /* close the file */
        f_close(&fatFsObjects.file);
        /* cannot continue with firmware update so go back to idle state */
        firmwareUpdateState = FIRMWARE_UPDATE_STATE_IDLE;
        return;
      }
      #if (BOOT_FILE_LOGGING_ENABLE > 0)
      FileFirmwareUpdateLogHook("OK\n\r");
      FileFirmwareUpdateLogHook("Closing firmware file\n\r");
      #endif
      /* close the file */
      f_close(&fatFsObjects.file);
      #if (BOOT_FILE_LOGGING_ENABLE > 0)
      FileFirmwareUpdateLogHook("Firmware update successfully completed\n\r");
      #endif
      /* all done so transistion back to idle mode */
      firmwareUpdateState = FIRMWARE_UPDATE_STATE_IDLE;
      #if (BOOT_FILE_COMPLETED_HOOK_ENABLE > 0)
      /* inform application about update completed event via hook function */
      FileFirmwareUpdateCompletedHook();
      #endif
      /* attempt to start the user program now that programming is done. note that
       * a call to CpuReset() won't work correctly here, because if the same firmware
       * file is still on the locally attached storage, it will just restart the
       * firmware update again and again..
       */
      CpuStartUserProgram();
    }
  }
} /*** end of FileTask ***/


/****************************************************************************************
** NAME:           SrecGetLineType
** PARAMETER:      line    a line from the S-Record
** RETURN VALUE:   the S-Record line type.
** DESCRIPTION:    Inspects a line from a Motorola S-Record file to determine its type.
**
****************************************************************************************/
static tSrecLineType SrecGetLineType(const blt_char *line)
{
  /* check if the line starts with the 'S' character, followed by a digit */
  if ( (toupper(line[0]) != 'S') || (isdigit(line[1]) == 0) )
  {
    /* not a valid S-Record line type */
    return LINE_TYPE_UNSUPPORTED;
  }
  /* determine the line type */
  if (line[1] == '1')
  {
    return LINE_TYPE_S1;
  }
  if (line[1] == '2')
  {
    return LINE_TYPE_S2;
  }
  if (line[1] == '3')
  {
    return LINE_TYPE_S3;
  }
  /* still here so not a supported line type found */
  return LINE_TYPE_UNSUPPORTED;
} /*** end of SrecGetLineType ***/


/****************************************************************************************
** NAME:           SrecVerifyChecksum
** PARAMETER:      line    an S1, S2 or S3 line from the S-Record
** RETURN VALUE:   BLT_TRUE if the checksum is correct, BLT_FALSE otherwise.
** DESCRIPTION:    Inspects an S1, S2 or S3 line from a Motorola S-Record file to
**                 determine if the checksum at the end is corrrect.
**
****************************************************************************************/
static blt_bool SrecVerifyChecksum(const blt_char *line)
{
  blt_int16u bytes_on_line;
  blt_int8u  checksum = 0;
  
  /* adjust pointer to point to byte count value */
  line += 2;
  /* read out the number of byte values that follow on the line */
  bytes_on_line = FileLibHexStringToByte(line);
  /* byte count is part of checksum */
  checksum += bytes_on_line;
  /* adjust pointer to the first byte of the address */
  line += 2;
  /* add byte values of address and data, but not the final checksum */
  do 
  {
    /* add the next byte value to the checksum */
    checksum += FileLibHexStringToByte(line);
    /* update counter */
    bytes_on_line--;
    /* point to next hex string in the line */
    line += 2;
  } 
  while (bytes_on_line > 1);
  /* the checksum is calculated by summing up the values of the byte count, address and
   * databytes and then taking the 1-complement of the sum's least signigicant byte */
  checksum = ~checksum;
  /* finally verify the calculated checksum with the one at the end of the line */
  if (checksum != FileLibHexStringToByte(line))
  {
    /* checksum incorrect */
    return BLT_FALSE;
  }
  /* still here so the checksum was correct */
  return BLT_TRUE;
} /*** end of SrecVerifyChecksum ***/


/****************************************************************************************
** NAME:           SrecParseLine
** PARAMETER:      line    a line from the S-Record
**                 address address found in the S-Record data line
**                 data    byte array where the data bytes from the S-Record data line
**                         are stored.
** RETURN VALUE:   the number of data bytes found on the S-record data line, 0 in case 
**                 the line is not an S1, S2 or S3 line or ERROR_SREC_INVALID_CHECKSUM
**                 in case the checksum validation failed.
** DESCRIPTION:    Parses a line from a Motorola S-Record file and looks for S1, S2 or S3 
**                 lines with data. Note that if a null pointer is passed as the data
**                 parameter, then no data is extracted from the line.
**
****************************************************************************************/
static blt_int16s SrecParseLine(const blt_char *line, blt_addr *address, blt_int8u *data)
{
  tSrecLineType lineType;
  blt_int16s    data_byte_count = 0;
  blt_int16u    bytes_on_line;
  blt_int16u    i;
  
  /* check pointers and not that data can be a null pointer */
  ASSERT_RT((address != BLT_NULL) && (line != BLT_NULL));
  /* figure out what type of line we are dealing with */
  lineType = SrecGetLineType(line);
  /* make sure it is one that we can parse */
  if (lineType == LINE_TYPE_UNSUPPORTED)
  {
    /* not a parsing error, but simply no data on this line */
    return 0;
  }
  /* verify the checksum */
  if (SrecVerifyChecksum(line) == BLT_FALSE)
  {
    /* error on data line encountered */
    return ERROR_SREC_INVALID_CHECKSUM;
  }
  /* all good so far, now read out the address and databytes for the line */
  switch (lineType)
  {
    /* ---------------------------- S1 line type ------------------------------------- */
    case LINE_TYPE_S1:
      /* adjust pointer to point to byte count value */
      line += 2;
      /* read out the number of byte values that follow on the line */
      bytes_on_line = FileLibHexStringToByte(line);
      /* read out the 16-bit address */
      line += 2;
      *address = FileLibHexStringToByte(line) << 8;
      line += 2;
      *address += FileLibHexStringToByte(line);
      /* adjust pointer to point to the first data byte after the address */
      line += 2;
      /* determine how many data bytes are on the line */
      data_byte_count = bytes_on_line - 3; /* -2 bytes address, -1 byte checksum */
      /* read and store data bytes if requested */
      if (data != BLT_NULL)
      {
        for (i=0; i<data_byte_count; i++)
        {
          data[i] = FileLibHexStringToByte(line);
          line += 2;
        }
      }
      break;
      
    /* ---------------------------- S2 line type ------------------------------------- */
    case LINE_TYPE_S2:
      /* adjust pointer to point to byte count value */
      line += 2;
      /* read out the number of byte values that follow on the line */
      bytes_on_line = FileLibHexStringToByte(line);
      /* read out the 32-bit address */
      line += 2;
      *address = FileLibHexStringToByte(line) << 16;
      line += 2;
      *address += FileLibHexStringToByte(line) << 8;
      line += 2;
      *address += FileLibHexStringToByte(line);
      /* adjust pointer to point to the first data byte after the address */
      line += 2;
      /* determine how many data bytes are on the line */
      data_byte_count = bytes_on_line - 4; /* -3 bytes address, -1 byte checksum */
      /* read and store data bytes if requested */
      if (data != BLT_NULL)
      {
        for (i=0; i<data_byte_count; i++)
        {
          data[i] = FileLibHexStringToByte(line);
          line += 2;
        }
      }
      break;
      
    /* ---------------------------- S3 line type ------------------------------------- */
    case LINE_TYPE_S3:
      /* adjust pointer to point to byte count value */
      line += 2;
      /* read out the number of byte values that follow on the line */
      bytes_on_line = FileLibHexStringToByte(line);
      /* read out the 32-bit address */
      line += 2;
      *address = FileLibHexStringToByte(line) << 24;
      line += 2;
      *address += FileLibHexStringToByte(line) << 16;
      line += 2;
      *address += FileLibHexStringToByte(line) << 8;
      line += 2;
      *address += FileLibHexStringToByte(line);
      /* adjust pointer to point to the first data byte after the address */
      line += 2;
      /* determine how many data bytes are on the line */
      data_byte_count = bytes_on_line - 5; /* -4 bytes address, -1 byte checksum */
      /* read and store data bytes if requested */
      if (data != BLT_NULL)
      {
        for (i=0; i<data_byte_count; i++)
        {
          data[i] = FileLibHexStringToByte(line);
          line += 2;
        }
      }
      break;

    default:
      break;
  }
  
  return data_byte_count;
} /*** end of SrecParseLine ***/


#if (BOOT_FILE_LOGGING_ENABLE > 0)
/****************************************************************************************
** NAME:           FileLibByteNibbleToChar
** PARAMETER:      nibble 4-bit value to convert
** RETURN VALUE:   The resulting byte value
** DESCRIPTION:    Helper function to convert a 4-bit value to a character that repre-
**                 sents its value in hexadecimal format.
**                 Example: FileLibByteNibbleToChar(11)  --> returns 'B'.
**
****************************************************************************************/
static blt_char FileLibByteNibbleToChar(blt_int8u nibble)
{
  blt_char  c;
  
  /* convert to ASCII value */
  c = (nibble & 0x0f) + '0';
  if (nibble > 9)
  {
    c += 7;
  }
  else
  {
    c = toupper(c);
  }
  /* return the character */
  return c;
} /*** end of FileLibByteNibbleToChar ***/


/****************************************************************************************
** NAME:           FileLibByteToHexString
** PARAMETER:      byte_val    8-bit value to convert
**                 destination pointer to character buffer for storing the results.
** RETURN VALUE:   The resulting string
** DESCRIPTION:    Helper function to convert a byte value to a string representing the
**                 value in hexadecimal format.
**                 Example: FileLibByteToHexString(28, strBuffer)  --> returns "1C".
**
****************************************************************************************/
static blt_char *FileLibByteToHexString(blt_int8u byte_val, blt_char *destination)
{
  /* first the most significant n-bit nibble */
  destination[0] = FileLibByteNibbleToChar(byte_val >> 4);
  /* next the least significant n-bit nibble */
  destination[1] = FileLibByteNibbleToChar(byte_val & 0x0f);
  /* add string termination */
  destination[2] = '\0';
  /* return pointer to resulting string */
  return destination;
} /*** end of FileLibByteToHexString ***/


/****************************************************************************************
** NAME:           FileLibLongToIntString
** PARAMETER:      hexstring string beginning with 2 characters that represent a hexa-
**                           decimal value
** RETURN VALUE:   The resulting string
** DESCRIPTION:    Helper function to convert a 32-bit unsigned number to a string that
**                 represents its decimal value.
**                 Example: FileLibLongToIntString(1234, strBuffer)  --> returns "1234".
**
****************************************************************************************/
static blt_char *FileLibLongToIntString(blt_int32u long_val, blt_char *destination)
{
  blt_int32u long_val_cpy = long_val;
  
  /* first determine how many digits there will be */
  do
  {
    destination++;
    long_val_cpy /= 10;
  }
  while (long_val_cpy > 0);
  /* add space for the string termination and add it */
  *destination = '\0';
  /* now add the digits from right to left */  
  long_val_cpy = long_val;
  do
  {
    /* set write pointer to where the next character should go */
    destination--;
    /* write digit in ASCII format */
    *destination = long_val_cpy % 10 + '0';
    /* move on to the next digit */
    long_val_cpy /= 10;
  }
  while (long_val_cpy > 0);

  return destination;
} /*** end of FileLibLongToIntString ***/
#endif /* (BOOT_FILE_LOGGING_ENABLE > 0) */


/****************************************************************************************
** NAME:           FileLibHexStringToByte
** PARAMETER:      hexstring string beginning with 2 characters that represent a hexa-
**                           decimal value
** RETURN VALUE:   The resulting byte value
** DESCRIPTION:    Helper function to convert a sequence of 2 characters that represent
**                 a hexadecimal value to the actual byte value.
**                 Example: FileLibHexStringToByte("2f")  --> returns 47.
**
****************************************************************************************/
static blt_int8u FileLibHexStringToByte(const blt_char *hexstring)
{
  blt_int8u result = 0;
  blt_char  c;
  blt_int8u counter;
  
  /* a hexadecimal character is 2 characters long (i.e 0x4F minus the 0x part) */
  for (counter=0; counter < 2; counter++)
  {
    /* read out the character */
    c = toupper(hexstring[counter]);
    /* check that the character is 0..9 or A..F */
    if ( (c < '0') || (c > 'F') || ( (c > '9') && (c < 'A') ) )
    {
      /* character not valid */
      return 0;
    }
    /* convert character to 4-bit value (check ASCII table for more info) */
    c -= '0';
    if (c > 9) 
    {
      c -= 7;
    }
    /* add it to the result */
    result = (result << 4) + c;
  }
  /* return the results */
  return result;
} /*** end of FileLibHexStringToByte ***/

#endif /* BOOT_FILE_SYS_ENABLE > 0 */


/*********************************** end of file.c *************************************/