[語法] RS232裡面的一些函數(以查過很多資料)

看板C_and_CPP作者gg1122 (99通未接來電)時間15年前 (2009/07/14 23:54)推噓0(0推 0噓 16→)

留言16則, 4人參與討論串1/1

目前在學習RS232 所以就直接拿別人的CODE來看但有幾行函數網路上找很多資料都還是沒辦法了解對方的表達意思希望各位先進能幫忙解答非常感謝妳主要是meset這行跟 WaitForSingleObject 這二個 WaitForSingleObject 這不是應該要判斷回傳訊息嗎? 我看read 跟write都沒判斷我查msdn WaitForSingleObject如果回傳WAIT_OBJECT_0 在判斷GetOverlappedResult 之後回傳true然後data_counter++ 這是我的想法可是網路上的code跟我想的都不一樣但跑出來的結果又是正確的有人能解說一下這邊的 read&write分別用 WaitForSingleObject 哪幾行說明嗎? 參考網址程式: http://www.edaboard.com/ftopic51410.html msdn:http://msdn.microsoft.com/en-us/library/ms810467.aspx CSerial::CSerial() { 　memset( &m_OverlappedRead, 0, sizeof( OVERLAPPED ) );//??作用? 　memset( &m_OverlappedWrite, 0, sizeof( OVERLAPPED ) );//??作用? } BOOL CSerial::WriteCommByte( unsigned char ucByte ) { BOOL bWriteStat; DWORD dwBytesWritten; bWriteStat = WriteFile( m_hIDComDev, (LPSTR) &ucByte, 1, &dwBytesWritten, &m_OverlappedWrite ); if( !bWriteStat && ( GetLastError() == ERROR_IO_PENDING ){ if( WaitForSingleObject( m_OverlappedWrite.hEvent, 1000 ) )//這不是要判斷 dwBytesWritten = 0; //不懂回傳的訊息 else { GetOverlappedResult( m_hIDComDev,&m_OverlappedWrite,&dwBytesWritten,FALSE); m_OverlappedWrite.Offset += dwBytesWritten; } } return( TRUE ); } int CSerial::ReadData( void *buffer, int limit) { if( !m_bOpened || m_hIDComDev == NULL ) return( 0 ); BOOL bReadStatus; DWORD dwBytesRead, dwErrorFlags; COMSTAT ComStat; ClearCommError( m_hIDComDev, &dwErrorFlags, &ComStat ); if( !ComStat.cbInQue ) return( 0 ); dwBytesRead = (DWORD) ComStat.cbInQue; if( limit < (int) dwBytesRead ) dwBytesRead = (DWORD) limit; bReadStatus = ReadFile( m_hIDComDev, buffer, dwBytesRead, &dwBytesRead, &m_OverlappedRead ); if(!bReadStatus ) { if( GetLastError() == ERROR_IO_PENDING ) { WaitForSingleObject( m_OverlappedRead.hEvent, 2000 );//不懂 return( (int) dwBytesRead ); //不懂 } return( 0 ); } } -- ※ 發信站: 批踢踢實業坊(ptt.cc) ◆ From: 61.216.18.65

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iamivers0n

07/14 23:56, , 1^F

07/14 23:56, 1^F

※ 編輯: gg1122 來自: 61.216.18.65 (07/15 00:06)

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james732

07/14 23:59, , 2^F

07/14 23:59, 2^F

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james732

07/14 23:59, , 3^F