视窗串行通信C++

我是c++和windows串行通信的新手。现在我正在关注微软链接，但是我不知道以下变量的含义这些变量有什么作用。请帮助我了解以下变量。我不知道的变量

1. 伊普布夫
2. dwRead

法典

DWORD dwRead;
BOOL fWaitingOnRead = FALSE;
OVERLAPPED osReader = {0};
// Create the overlapped event. Must be closed before exiting
// to avoid a handle leak.
osReader.hEvent = CreateEvent(NULL, TRUE, FALSE, NULL);
if (osReader.hEvent == NULL)
   // Error creating overlapped event; abort.
if (!fWaitingOnRead) {
   // Issue read operation.
   if (!ReadFile(hComm, lpBuf, READ_BUF_SIZE, &dwRead, &osReader)) {
      if (GetLastError() != ERROR_IO_PENDING)     // read not delayed?
         // Error in communications; report it.
      else
         fWaitingOnRead = TRUE;
   }
   else {    
      // read completed immediately
      HandleASuccessfulRead(lpBuf, dwRead);
    }
}