function SplitFile(Filename, DestFolder: string; SplitSize, CntParts: Int64): Int64;
const
  //BLOCKSIZE = 1048544;
  BLOCKSIZE = 32767;
resourcestring
  ChangeDiskMsg = 'Legen sie die nächste Diskette in Laufwerk a: ein.';
var
  hFile : THandle;
  SizeOfFile : Int64; // >4GB
  hPart : THandle;
  Loop : Cardinal;
  Partname : string;
  MemBuffer : array[0..BLOCKSIZE - 1] of Byte;
  BytesToRead, BytesRead, BytesWritten: Int64;
  TotalBytesRead, OverallBytesRead: Int64;
  ProgressCurrent, ProgressOld: Cardinal;
begin
  bRunning := 1;
  OverallBytesRead := 0;
  SizeOfFile := GetFileSize(PChar(Filename));
  hFile := FileOpen(Filename, $0000);
  if hFile <> INVALID_HANDLE_VALUE then
  begin
    for Loop := 1 to CntParts do
    begin
      // Reset variables
      TotalBytesRead := 0;
      ProgressOld := 0;
      BytesToRead := SplitSize;
      // build filename of the parts
      Partname := DestFolder + '\' + ExtractFilename(Filename) + Format('.%3.3d', [Loop]);
      if FileExists(Partname) then
        DeleteFile(PChar(Partname));
      hPart := FileCreate(Partname);
      if hPart <> INVALID_HANDLE_VALUE then
      begin
        repeat
          BytesRead := FileRead(hFile, MemBuffer, Min(sizeof(MemBuffer), BytesToRead));
          BytesWritten := FileWrite(hPart, MemBuffer, BytesRead);
          Dec(BytesToRead, sizeof(MemBuffer));
          // progress stuff ////////////////////////////////////////////////////
          TotalBytesRead := TotalBytesRead + BytesWritten;
          OverallBytesRead := OverallBytesRead + BytesWritten;
          ProgressCurrent := (OverallBytesRead * 100) div SizeOfFile;
          if ProgressCurrent <> ProgressOld then
          begin
            ProgressOld := ProgressCurrent;

          end;
          SendMessage(hApp, FSM_PROGRESS, ProgressCurrent, Integer(PChar(Partname)));
          //////////////////////////////////////////////////////////////////////
        until (BytesToRead <= 0) or (bRunning = 0);
      end;
      FileClose(hPart);
      if bRunning = 0 then
        Break;
      if (DestFolder = 'a:\') and (Loop < CntParts) then
      begin
        if MessageBox(0, PChar(ChangeDiskMsg), APPNAME, MB_ICONINFORMATION or MB_OKCANCEL) = ID_CANCEL then
        begin
          bRunning := 0;
          break;
        end;
      end;
    end;
    FileClose(hFile);
  end;
  SendMessage(hApp, FSM_FINISH, 0, GetLastError());
  result := GetLastError();
end;