事件標志

描述

EV_BREAK

檢測到輸入中的break

EV_CTS

CTS(Clear?To?Send)信號狀態改變。要取得CTS線路狀態，應使用GetCommModemStatus函數。

EV_DSR

DSR(Data?Set?Ready)信號狀態改變。要取得DSR線路狀態，應使用GetCommModemStatus函數。

EV_ERR

某線路狀態錯誤發生。線路狀態錯誤包括CE_FRAME、CE_OVERRUN和CE_RXPARITY。要取得具體錯誤種類，需調用ClearCommError函數。

EV_RING

檢測到振鈴指示

EV_RLSD

RLSD(Receive?Line?Signal?Detect)信號狀態改變。要取得RLSD線路狀態，需調用GetCommModemStatus函數。注意，RLSD通常被稱作CD(carrier?detect)。

EV_RXCHAR

接收到一個字符并且已放入輸入緩沖區。請參考下面的“警告”節對此標志的詳細討論。

EV_RXFLAG

接收到一個事件字符并且已放入輸入緩沖區。事件字符由下文討論的DCB結構EvtChar字段指定。下面的“警告”節也討論了這個標志。

EV_TXEMPTY

輸出緩沖區中最后一個字符被發送到串口設備了。如果使用硬件緩沖區，此標志僅表示所有數據已經發送到硬件了。如果不與設備驅動交互，是無法確定硬件緩沖區空的。

?? #define?STATUS_CHECK_TIMEOUT??????500???//?Milliseconds

???DWORD??????dwRes;
???DWORD??????dwCommEvent;
???DWORD??????dwStoredFlags;
???BOOL??????fWaitingOnStat?=?FALSE;
???OVERLAPPED?osStatus?=?{0};
???dwStoredFlags?=?EV_BREAK?|?EV_CTS?|?EV_DSR?|?EV_ERR?|?EV_RING?|\
??????????????????EV_RLSD?|?EV_RXCHAR?|?EV_RXFLAG?|?EV_TXEMPTY?;
???if?(!SetCommMask(comHandle,?dwStoredFlags))
??????//?error?setting?communications?mask;?abort
??????return?0;
???osStatus.hEvent?=?CreateEvent(NULL,?TRUE,?FALSE,?NULL);
???if?(osStatus.hEvent?==?NULL)
??????//?error?creating?event;?abort
??????return?0;
???for?(?;?;?)?{
??????//?Issue?a?status?event?check?if?one?hasn't?been?issued?already.
??????if?(!fWaitingOnStat)?{
?????????if?(!WaitCommEvent(hComm,?&dwCommEvent,?&osStatus))?{
????????????if?(GetLastError()?==?ERROR_IO_PENDING)
???????????????bWaitingOnStatusHandle?=?TRUE;
????????????else
???????????????//?error?in?WaitCommEvent;?abort
???????????????break;
?????????}
?????????else
????????????//?WaitCommEvent?returned?immediately.
????????????//?Deal?with?status?event?as?appropriate.
????????????ReportStatusEvent(dwCommEvent);?
??????}
??????//?Check?on?overlapped?operation.
??????if?(fWaitingOnStat)?{
?????????//?Wait?a?little?while?for?an?event?to?occur.
?????????dwRes?=?WaitForSingleObject(osStatus.hEvent,?STATUS_CHECK_TIMEOUT);
?????????switch(dwRes)
?????????{
?????????????//?Event?occurred.
?????????????case?WAIT_OBJECT_0:?
?????????????????if?(!GetOverlappedResult(hComm,?&osStatus,?&dwOvRes,?FALSE))
????????????????????//?An?error?occurred?in?the?overlapped?operation;
????????????????????//?call?GetLastError?to?find?out?what?it?was
????????????????????//?and?abort?if?it?is?fatal.
?????????????????else
????????????????????//?Status?event?is?stored?in?the?event?flag
????????????????????//?specified?in?the?original?WaitCommEvent?call.
????????????????????//?Deal?with?the?status?event?as?appropriate.
????????????????????ReportStatusEvent(dwCommEvent);
?????????????????//?Set?fWaitingOnStat?flag?to?indicate?that?a?new
?????????????????//?WaitCommEvent?is?to?be?issued.
?????????????????fWaitingOnStat?=?FALSE;
?????????????????break;
?????????????case?WAIT_TIMEOUT:
?????????????????//?Operation?isn't?complete?yet.?fWaitingOnStatusHandle?flag?
?????????????????//?isn't?changed?since?I'll?loop?back?around?and?I?don't?want
?????????????????//?to?issue?another?WaitCommEvent?until?the?first?one?finishes.
?????????????????//
?????????????????//?This?is?a?good?time?to?do?some?background?work.
????????????????DoBackgroundWork();
?????????????????break;???????????????????????
?????????????default:
?????????????????//?Error?in?the?WaitForSingleObject;?abort
?????????????????//?This?indicates?a?problem?with?the?OVERLAPPED?structure's
?????????????????//?event?handle.
????????????????CloseHandle(osStatus.hEvent);
????????????????return?0;
?????????}
??????}
???}
???CloseHandle(osStatus.hEvent);