Format of the SPF DIF file (last updated in v0.70 dev 0604):

  0000h  0020h  Header
  0020h  ????   Block data (plain for SPFD, ZLib-compressed for SPFZ)

  Header:

    0000h  0004h  'SPFD' or 'SPFZ' or 'SPFX' (see *7 for 'SPFX')
                  DIF signature
    0004h  0004h  ASCII Phone ID
    0008h  0010h  ASCIIZ (00h) right-padded software ID
    0018h  0004h  Reserved
    001Ch  0004h  Number of blocks in block data area

  Block:

    0000h  000Ch  Block header
    000Ch  ????   Data

    Block header:

      0000h  0004h  'FBLK' signature
      0004h  0004h  Block type
      0008h  0004h  Block size

    Common dIFC type block data:
      0000h  ????   RTF comment

    Common class dChK checking block data:
      0000h  0004h  Reserved (00000000h)

    SGHA class NORD/nOrR type block data:

      0000h  0004h  Starting address in NOR flash (see *8)
      0004h  ????   NOR data

    SGHA class TFSF type block data:

      0000h  0004h  Filename length
      0004h  ????   Full TFS filename
      ????   ????   TFS file data

    SGHA class fLDR type block data:

      0000h  ????   Full TFS folder name

Comments:

1. Phone ID is phone class ID. If SGHFD (or other software) does not know
   how to process phone class specified, it must display an error and stop
   processing. You can not intermix multiple phone classes in one DIF file.

   Phone classes currently known by SGHFD:
     'SGHA': Samsung SGH series phones
                             
2. Software ID must be right-padded by zeros up to 16 bytes length.
   It is given just for informational purposes and is not processed 
   by SGHFD in any way.

   Examples:
     'X100XEDG1', 0, 0, 0, 0, 0, 0, 0.
     'AUTODIFF TOOL', 0, 0, 0

3. Block naming conventions:

   First block name letter defines 'mandatory' block if it is capital and
   'optional' block if it is small. If the first letter is capital and
   SGHFD (or other software) does not know how to parse that block, it
   must stop parsing here and display an error message. If the first
   letter is small and software does not know how to parse it, it must
   skip and ignore that block.

   Second block name letter defines 'author' block if it is capital and
   'third-party' block if it is small. 'Author' blocks are blocks defined
   by the author of SGHFD. If you want to make your own private block
   extension to DIF, you must keep second letter small to ensure it will
   not conflict with future SGHFD versions.

   Third block name letter defines 'safe to copy' block if it is capital
   and 'unsafe to copy' block if it is small. When processing DIF file
   to include it into other DIF file, or when modifying DIF file someway,
   blocks marked with small third letter ('unsafe to copy' blocks) which
   are not known by the processing software must not be processed, and must
   be thrown out.

   Common author blocks currently known by SGHFD:
     'dIFC' - DIF comment in RTF (Rich Text Format), multiple dIFC
              blocks are joined by SGHFD into single comment
     'dChK' - DIF checking enable flag, if it is present then checking
              is performed in Normal checking mode using nOrR data from
              the DIF. Checking ensures that the DIF is compatible with
              other DIF's and firmware present in phone (or BIN file,
              during depacking). v0.70 and higher only, unsafe to copy
              non-mandatory block.

   Author blocks known by SGHFD for 'SGHA' class phones:
     'NORD' - NOR flash data
     'nOrR' - NOR reversal (undo) data
     'TFSF' - TFS file
     'fLDR' - TFS folder (NOTE! Folders present in 'TFSF' blocks must be
              created in filesystem too. 'fLDR' is optional block type
              that can be used to create empty folders). This block type
              has meaning in SGHFD 0.70 or higher only.

4. Starting address in the is the linear address in phone flash.

5. For 'SGHA' class phones, internal NOR flash blocks have 10000h
   bytes granularity (not all the blocks, really, but the flasher emulates
   10000h granularity where needed). If the NOR block being written is not
   granular on start/end, remaining granularity unit data will be read from
   the phone itself at the flashing stage. This makes patching a few bytes
   pretty easy.

6. 'SPFZ' files are generic SPF DIF files where the block data itself is
   compressed with ZLib as a single datastream.

7. 'SPFX' files are XML DIF files, their format greatly differ from the
   standard DIF. If you see 'SPFX' in the first 4 bytes, you must follow
   recommendations in dif-xml-format.txt for further DIF processing.

8. NORD/nOrR address is FLASH address. There is common mistake with Swift
   series to make these addresses starting at not at 0x0 but at 0x10000000.
   Such DIFs will be tolerated only if they are ResMan ones (and the
   workaround will be completely removed in SGHFD v0.72. Real flash
   addresses start at 0x0 and never at any other address.