fat16driver.bas

MSP430最基本的应用开发实例

' * The resulting values are stored in the global variables starting with 
Mbr_
' **
Sub Readmbr()

  'output some debug info
  Call Debug( "ReadMBR()")

  'set the offset values
  G_offset = 447

  'point to the first byte of the array
  G_pointer = Varptr(g_xferbuffer(1))

  'MBR is always sector #0
  G_sectnum = 0

  'debug
  Print "Reading MBR at Sector: " ; G_sectnum
  'Call Debug(g_debugtext)

  'read sector number 1 into the 512 byte array starting at the pointer 
address
  Readsector G_pointer , G_sectnum , 1

  'see if the value is greater than 0, otherwise, that partition not defined
  If G_xferbuffer(g_offset) > 0 Then

     'update the offset value
     G_offset = G_offset + 4

     'read the filesystem type from the transfer buffer
     Mbr_fstype = G_xferbuffer(g_offset)
     Print "File System Type: " ; Hex(mbr_fstype)

     G_offset = G_offset + 3

     'read the starting sector for the partition
     Mbr_sectfrom = Getlongfrombuffer(g_xferbuffer(1) , G_offset)
     Print "Start Sector: " ; Mbr_sectfrom

     If Mbr_fstype = &H0B Then
       Mbr_fatoffset = 4
       Mbr_sectorsinroot = 0
       Print "Filesystem: FAT32"
     End If

     If Mbr_fstype = &H06 Then
       Mbr_fatoffset = 2
       Mbr_sectorsinroot = 14
       Print "Filesystem: FAT16"
     End If

     If Mbr_fstype < &H06 Then
       Mbr_fatoffset = 1.5
       Mbr_sectorsinroot = 32
       Print "Filesystem: FAT12"
     End If

  End If

End Sub

' **
' * This function is used to read boot record for a given partition
' **
Sub Readbootrecord()

  Print "ReadBootRecord()"

  'point to the first byte of the array
  G_pointer = Varptr(g_xferbuffer(1))

  Print "Reading from Sector " ; Mbr_sectfrom

  'find the starting sector from the partition table lookup
  G_sectnum = Mbr_sectfrom

  'read sector number 1 into the 512 byte array starting at the pointer 
address
  Readsector G_pointer , G_sectnum , 1

  'set the offset and get the bytes per sector field
  G_offset = 11
  Br_bytespersector = Getwordfrombuffer(g_xferbuffer(1) , G_offset)

  'set the offset and get the sectors per cluster field
  G_offset = G_offset + 2
  Br_sectorspercluster = G_xferbuffer(g_offset + 1)

  'set the offset and get the reserved sectors
  G_offset = G_offset + 1
  Br_reservedsectors = Getwordfrombuffer(g_xferbuffer(1) , G_offset)

  'set the offset and get the copies of fat
  G_offset = G_offset + 2
  Br_copiesoffat = G_xferbuffer(g_offset + 1)

  'set the offset and get the max number of root entries
  G_offset = G_offset + 1
  Br_maxrootentries = Getwordfrombuffer(g_xferbuffer(1) , G_offset)

  'set the offset and get the sectors per fat
  If Mbr_fstype < &H0B Then

    'reads the sectors per fat for FAT12/16
    G_offset = G_offset + 5
    Br_sectorsperfat = Getwordfrombuffer(g_xferbuffer(1) , G_offset)

  Else
    'reads the sectors per fat for FAT32
    G_offset = G_offset + 19
    Br_sectorsperfat = Getwordfrombuffer(g_xferbuffer(1) , G_offset)

    'set the offset and get the root directory starting cluster
    G_offset = G_offset + 1
    Br_rootcluster = Getlongfrombuffer(g_xferbuffer(1) , G_offset)

  End If

  'start by adding the starting sector with the reserved sectors
  Br_actualstartsector = Mbr_sectfrom + Br_reservedsectors

  'calculate all of the sectors in every copy of the FAT table
  Br_sectorsinallfats = Br_sectorsperfat * Br_copiesoffat

  'add the total sectors in all copies of the FAT table
  Br_actualstartsector = Br_actualstartsector + Br_sectorsinallfats

  'calc the data sector offset based on the max entries * 32 (32 bytes each)
  Data_sectoffset = Br_maxrootentries * 32

  'devide the offset by bytes per sector to determine the sector number
  Data_sectorcluster = Data_sectoffset / Br_bytespersector

  Data_sector = Br_actualstartsector + Data_sectorcluster

  'For Cntr = 1 To 120
  ' Print Xferbuffer(cntr) ; " ";
  'Next Cntr
  'Print " "

  Print "Bytes per sector: " ; Br_bytespersector
  Print "Sectors per cluster: " ; Br_sectorspercluster
  Print "Sectors per fat: " ; Br_sectorsperfat
  Print "Reserved sectors: " ; Br_reservedsectors
  Print "Copies of fat: " ; Br_copiesoffat
  Print "Max root entries: " ; Br_maxrootentries

End Sub

' **
' * This function is used to return a long datatype from the buffer
' *
' * Code originated by Josef Franz
' **
Function Getlongfrombuffer(pbsramarray As Byte , Byval Pbpos As Word) As 
Long
   ' Extract a Long-Value from a Byte-Array
   ' pbSRAMArray: Byte-array, from which the Long-value should be extracted
   ' pbPos: Position, at which the Long-Value starts (0-based)
   Loadadr Pbsramarray , Z
   Loadadr Pbpos , X
   ld r24, x+
   ld r25, x+
   add zl, r24
   adc zh, r25
   Loadadr Getlongfrombuffer , X
   ldi r24, 4
   !Call _Mem_Copy
End Function

' **
' * This function is used to return a word datatype from the buffer
' *
' * Code originated by Josef Franz
' **
Function Getwordfrombuffer(pbsramarray As Byte , Byval Pbpos As Word) As 
Word
   ' Extract a Word-value from a Byte-Array
   ' pbSRAMArray: Byte-array, from which the Word-value should be extracted
   ' pbPos: Position, at which the Word-Value starts (0-based)
   Loadadr Pbsramarray , Z
   Loadadr Pbpos , X
   ld r24, x+
   ld r25, x+
   add zl, r24
   adc zh, r25
   Loadadr Getwordfrombuffer , X
   ldi r24, 2
   !Call _Mem_Copy
End Function

' **
' * Used to convert a long value to 4 bytes
' **
Sub Convertlong(byval Longvalue As Long)

  'set the long value outside the frame
  Conv_long = Longvalue
  Conv_string = Hex(conv_long)

  'parse the HEX string value as 2 char strings
  Conv_strbytes(1) = Mid(conv_string , 1 , 2)
  Conv_strbytes(2) = Mid(conv_string , 3 , 2)
  Conv_strbytes(3) = Mid(conv_string , 5 , 2)
  Conv_strbytes(4) = Mid(conv_string , 7 , 2)

  'convert the bit order to little endian
  Conv_bytes(4) = Hexval(conv_strbytes(1))
  Conv_bytes(3) = Hexval(conv_strbytes(2))
  Conv_bytes(2) = Hexval(conv_strbytes(3))
  Conv_bytes(1) = Hexval(conv_strbytes(4))
End Sub

' **
' * Used to convert a long value to 4 bytes
' **
Sub Convertword(byval Wordvalue As Word)

  'set the long value outside the frame
  Convw_word = Wordvalue
  Convw_string = Hex(convw_word)

  'parse the HEX string value as 2 char strings
  Convw_strbytes(1) = Mid(convw_string , 1 , 2)
  Convw_strbytes(2) = Mid(convw_string , 3 , 2)

  'convert the bit order to little endian
  Convw_bytes(2) = Hexval(convw_strbytes(1))
  Convw_bytes(1) = Hexval(convw_strbytes(2))
End Sub

' **
' * This sub sets the debug output device
' *
' * Set to 1 for RS232
' * Set to 2 for LCD
' **
Sub Setdebug(byval Debugvalue As Byte)

  'set the global debug value
  G_debug = Debugvalue

End Sub


' **
' * This sub prints a message to the RS232 or LCD if the debug is set
' **
Sub Debug(byval Debugtext As String)

  'if debug is set to 1, select the RS232 output device
  If G_debug = 1 Then
    Print Debugtext
  End If

  'if debug is set to 2, select the LCD output device
  If G_debug = 2 Then
    Lcd Debugtext
  End If

End Sub

' **
' * This function is used to parse a 512 byte sector for the 32 byte fat 
record
' **
Function Parsefatrecord(byval Recordnum As Word) As Byte

  'start at byte 0 offset
  G_offset = Recordnum * 32

  G_parse_temp = G_offset + 12

  'set the offset and read the attribute byte
  G_attribute = G_xferbuffer(g_parse_temp)

  'Print "REC: " ; Recordnum ; " OFFSET: " ; Offset ; "  ATTRIB: " ; 
Attribute

  'For Cntr = 1 To 32
  '  Parse_temp = Offset + Cntr
  '  Print Hex(xferbuffer(parse_temp)) ; " " ;
  'Next Cntr

  'Print ""

  'For Cntr = 1 To 32
  '  Parse_temp = Offset + Cntr
  '  Print Xferbuffer(parse_temp) ; " " ;
  'Next Cntr

  'Print ""

  'check the attribute byte to determine if this a a LFN ercord.
  'The attribute indicates that this is a LFN record if it's OFh
  If G_attribute = &H0F Then

    'LFN code goes here

  Else
    Fat_attribute = G_attribute

    'Print "VALUES: " ;
    'get the 8 byte short file name
    For G_cntr = 1 To 8
      G_offset = G_offset + 1
      Fat_shortname(g_cntr) = G_xferbuffer(g_offset)
    Next G_cntr

    'get the 3 byte file extension
    For G_cntr = 1 To 3
      G_offset = G_offset + 1
      Fat_extension(g_cntr) = G_xferbuffer(g_offset)
    Next G_cntr

    'get the files created milliseconds (ms)
    G_offset = G_offset + 1                                 'base 1 array 
requires +1
    Fat_createdms = G_xferbuffer(g_offset + 1)

    'get the create time as a word
    G_offset = G_offset + 2
    Fat_createdtm = Getwordfrombuffer(g_xferbuffer(1) , G_offset)

    'get the created date as a word
    G_offset = G_offset + 2
    Fat_createddt = Getwordfrombuffer(g_xferbuffer(1) , G_offset)

    'get the last access date as a word
    G_offset = G_offset + 2
    Fat_accessdt = Getwordfrombuffer(g_xferbuffer(1) , G_offset)

    'get the high 16 bits of the fat cluster as a word
    G_offset = G_offset + 2
    Fat_fathighcluster = Getwordfrombuffer(g_xferbuffer(1) , G_offset)

    'get the last update time as a word
    G_offset = G_offset + 2
    Fat_updatetime = Getwordfrombuffer(g_xferbuffer(1) , G_offset)

    'get the last update date as a word
    G_offset = G_offset + 2
    Fat_updatedate = Getwordfrombuffer(g_xferbuffer(1) , G_offset)

    'get the 16 bit fat cluster as a word
    G_offset = G_offset + 2
    Fat_cluster = Getwordfrombuffer(g_xferbuffer(1) , G_offset)

    'get the file size as a dword (long)
    G_offset = G_offset + 2
    'Print "long offset = " ; Offset
    Fat_filesize = Getlongfrombuffer(g_xferbuffer(1) , G_offset)

    If Fat_attribute > 31 And Fat_shortname(1) <> 229 Then
       For G_temp_cntr = 1 To 4
          G_temp_val = G_temp_cntr + G_offset
          'Print Xferbuffer(temp_val) ; " " ;
       Next G_temp_cntr
       'Print " = " ; Fat_filesize ; " Bytes at offset " ; Offset ; " cntr=" 
; Temp_cntr
    End If

    'point the offset to the end of the 32 byte record
    G_offset = G_offset + 4

    'set the volume name of attribute indicates this is a file
    If Fat_attribute > 31 And Fat_shortname(1) <> 229 Then
      Fat_filename = ""
        For G_cntr = 1 To 8                                 '
         If Fat_shortname(g_cntr) < 129 And Fat_shortname(g_cntr) > 33 Then
           'Print "'" ; Chr(fat_shortname(cntr)) ; "' " ; 
Hex(fat_shortname(cntr)) ; " " ;
           Fat_filename = Fat_filename + Chr(fat_shortname(g_cntr))
         End If
       Next G_cntr
       Fat_filename = Fat_filename + "."
       For G_cntr = 1 To 3
         If Fat_extension(g_cntr) < 129 And Fat_extension(g_cntr) > 33 Then
          Fat_filename = Fat_filename + Chr(fat_extension(g_cntr))
         End If
       Next Cntr
          'Print "file: " ; Fat_filename
    End If

  End If

  Parsefatrecord = G_attribute

End Function

' **
' * This function is used to list the files on the root dir
' **
Sub Listrootdir()

  'empty return value
  Local Returnvalue As Byte

  'call 'search' with a bogus filename
  ' NOTE: wild cards '*' are meaningless, this is a totally bogus filename
  Returnvalue = Searchrootdir( "*.*")

End Sub

' **
' * Lists a file contents as ascii text
' **
Sub Listfile(byval Fname As String)

  'search results
  Local Result As Byte

  'search for file
  Result = Searchrootdir(fname)

  'if file was found, dump it as ascii text
  If Result > 0 Then

    'dump the contents
    Call Dumpfile(fat_cluster , Fat_filesize)

  End If

End Sub

' **
' * This function is used to search the root dir for a file
' **
Function Searchrootdir(byval Searchname As String) As Byte

  'set the value out of the frame
  G_touchholder = Searchname

  'point to the first byte of the array
  G_pointer = Varptr(g_xferbuffer(1))

  Print "FAT start sector:" ; Br_actualstartsector ; " for dir entries"
  'Print "data start sector:" ; Datasector

  Print "Searching for " ; G_touchholder

  While G_rootloop <= Br_sectorsinroot

     'read sector number 1 into the 512 byte array starting at the pointer 
address
     Readsector G_pointer , Br_actualstartsector , 1

     'set the fat directory sector for future updates
     Fat_dirsector = Br_actualstartsector

     'start with record 0
     G_volumerecord = 0

     'exame each of 16 records on this sector until the volume attribute is 
found
     While G_volumerecord < 16

       'set the fat directory entry number for future updates
       Fat_direntry = G_volumerecord

       G_attribreturn = Parsefatrecord(g_volumerecord)

         'the attribute indicates this entry is a file
         If G_attribreturn > 31 And Fat_shortname(1) <> 229 Then

           Print "File: " ; Fat_filename

           'found the filename so return
           If Fat_filename = G_touchholder Then

             'set the return value and exit
             Searchrootdir = G_attribreturn
             G_rootloop = 99
             G_volumerecord = 99
           Else
             'file not found
             Searchrootdir = 0
           End If

         End If

       G_volumerecord = G_volumerecord + 1
     Wend

     Br_actualstartsector = Br_actualstartsector + 1
     G_rootloop = G_rootloop + 1
  Wend

End Function

' **
' * copy Memory from (Z) nach (X)
' * counts of bytes in r24
' *
' * Code originated by Josef Franz
' **
_mem_copy:
   ld r25, z+
   st x+, r25
   dec r24
   brne _Mem_Copy
   ret