CRC32()

Private Function CRC32(Data As String) As UInt32

  Dim ret As UInt32 = &HFFFFFFFF
  Dim i, j As Integer

  Dim CRC32Table As MemoryBlock = InitCRC32()

  For i = 1 To LenB(Data)
    j = AscB(MidB(Data, i, 1)) Xor (ret And &HFF)
    If ret < 0 Then ret = ((ret And &H7FFFFFFF) \ &H100) Or &H800000 Else ret = ret \ &H100
    ret = ret Xor CRC32Table.Int32Value(j * 4)
  Next

  ret = Not ret
  Return ret

End Function