typedef struct _COMSTAT 
{
  DWORD fCtsHold  :1;
  DWORD fDsrHold  :1;
  DWORD fRlsdHold  :1;
  DWORD fXoffHold  :1;
  DWORD fXoffSent  :1;
  DWORD fEof  :1;
  DWORD fTxim  :1;
  DWORD fReserved  :25;
  DWORD cbInQue;
  DWORD cbOutQue;
} COMSTAT, *LPCOMSTAT;