; CRC32 calculating macros
; v1.00
; for flat assembler by Grom PE
;
; Notes:
;   calculating CRC32 of 10 mb file takes about 17s on my Pentium4 1.7 GHz
;
; Limitations:
;   data between crc32start and crc32end must be duplicated in case you
;   want to include it in resulting file, that's because "virtual"
;   directive doesn't allow to "load" and "store" from outside of it.
;
; Usage example:
;
; crc32filecheck 'test.bin', 0xb5a214e8
; ; - Useful together with my patching macros, for example =)
; ;   (http://board.flatassembler.net/topic.php?t=8744)
;
; crc32start
;   db 'This string has its own CRC32:'
; crc32end
;   db 'This string has its own CRC32:'
;   dd crc32value

macro crc32start
{
  crc32value = 0xFFFFFFFF
  virtual
}

macro crc32end
{
  local _r, _t, _l
    _l = $-$$
    crc32table rd 256

    repeat 256
      _r = %-1
      repeat 8
        _r = _r shr 1 xor (0xEDB88320 * _r and 1)
      end repeat
      store dword _r at crc32table+%*4-4
    end repeat

    repeat _l
      load _p byte from $$+%-1
      load _t dword from crc32table+(_p xor (crc32value and 0xFF))*4
      crc32value = crc32value shr 8 xor _t
    end repeat
    crc32value = crc32value xor 0xFFFFFFFF
  end virtual
}

macro crc32file filename*
{
  crc32start
    file filename
  crc32end
}

macro crc32filecheck filename*, value*
{
  crc32file filename
  if crc32value <> value
    "Error: crc32 doesn't match!"
  end if
}    

macro embed_crc start,finish {
 local b,c
   c = 0xffffffff
      repeat finish-start
         load b byte from start+%-1
          c = c xor b
         repeat 8
                    c = (c shr 1) xor (0xedb88320 * (c and 1))
          end repeat
  end repeat
  dd c xor 0xffffffff
}    

MyCode:
   mov     eax,0x12345678
      xor     eax,edx
     ret

     embed_crc $$,$