Public Function CRC32(str As String) As Long
  Dim i As Long
  Dim j As Long
  Dim nPowers(0 To 7) As Integer
  Dim nCRC As Long
  Dim nByte As Integer
  Dim nBit As Boolean
 
  For i = 0 To 7
     nPowers(i) = 2 ^ i
  Next 'i
  For i = 1 To Len(str)
    nByte = Asc(Mid$(str, i, 1))
    For j = 7 To 0 Step -1
      nBit = CBool((nCRC And 32768) = 32768) Xor _
       ((nByte And nPowers(j)) = nPowers(j))
      nCRC = (nCRC And 32767&) * 2&
      If nBit Then
        nCRC = nCRC Xor &H8005&
      End If
    Next 'j
  Next 'i
  CRC32 = nCRC
End Function