20000804014.htm

C++Builder教学大全

          } <br>
          <br>
          // <br>
          // If there is a error, give the right message <br>
          // <br>
          void TSerialPort::ProcessErrorMessage(char* ErrorText) <br>
          { <br>
          char *Temp = new char[200]; <br>
          <br>
          <br>
          LPVOID lpMsgBuf; <br>
          <br>
          FormatMessage( <br>
          FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM, <br>
          NULL, <br>
          GetLastError(), <br>
          MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), // Default language <br>
          (LPTSTR) &amp;lpMsgBuf, <br>
          0, <br>
          NULL <br>
          ); <br>
          <br>
          sprintf(Temp, "WARNING: %s Failed with the following error: \n%s\nPo 
          <br>
          rt: %d\n", (char*)ErrorText, lpMsgBuf, m_nPortNr); <br>
          Application-&gt;MessageBox(Temp, "Application Error", MB_ICONSTOP); 
          <br>
          <br>
          LocalFree(lpMsgBuf); <br>
          delete[] Temp; <br>
          } <br>
          <br>
          // <br>
          // Write a character. <br>
          // <br>
          void TSerialPort::WriteChar(TSerialPort* port) <br>
          { <br>
          BOOL bWrite = true; <br>
          BOOL bResult = true; <br>
          <br>
          DWORD BytesSent = 0; <br>
          <br>
          ResetEvent(port-&gt;m_hWriteEvent); <br>
          <br>
          // Gain ownership of the critical section <br>
          EnterCriticalSection(&amp;port-&gt;m_csCommunicationSync); <br>
          <br>
          if (bWrite) <br>
          { <br>
          // Initailize variables <br>
          port-&gt;m_ov.Offset = 0; <br>
          port-&gt;m_ov.OffsetHigh = 0; <br>
          <br>
          // Clear buffer <br>
          PurgeComm(port-&gt;m_hComm, PURGE_RXCLEAR | PURGE_TXCLEAR | PURGE_R 
          <br>
          ABO <br>
          ABO <br>
          RT | PURGE_TXABORT); <br>
          <br>
          bResult = WriteFile(port-&gt;m_hComm, <br>
          / Handle to COMM Port <br>
          port-&gt;m_szWriteBuffer, / <br>
          / Pointer to message buffer in call <br>
          ing finction <br>
          strlen((char*)port-&gt;m_sz <br>
          riteBuffer), // Length of message to s <br>
          end <br>
          &amp;BytesSent, <br>
          / Where to store the number of bytes sent <br>
          &amp;port-&gt;m_ov); <br>
          / Overlapped structure <br>
          <br>
          // deal with any error codes <br>
          if (!bResult) <br>
          { <br>
          DWORD dwError = GetLastError(); <br>
          switch (dwError) <br>
          { <br>
          case ERROR_IO_PENDING: <br>
          { <br>
          // continue to GetOverlappedResu <br>
          ts() <br>
          BytesSent = 0; <br>
          bWrite = false; <br>
          break; <br>
          } <br>
          default: <br>
          { <br>
          // all other error codes <br>
          port-&gt;ProcessErrorMessage("Write <br>
          ile()"); <br>
          } <br>
          } <br>
          } <br>
          else <br>
          { <br>
          LeaveCriticalSection(&amp;port-&gt;m_csCommunicationSync); <br>
          } <br>
          } // end if(bWrite) <br>
          <br>
          if (!bWrite) <br>
          { <br>
          bWrite = true; <br>
          <br>
          bResult = GetOverlappedResult(port-&gt;m_hComm, // Handle to COM <br>
          port <br>
          <br>
          &amp;port- <br>
          m_ov, // Overlapped structure <br>
          &amp;Bytes <br>
          ent, // Stores number of bytes sent <br>
          true); <br>
          // Wait flag <br>
          <br>
          LeaveCriticalSection(&amp;port-&gt;m_csCommunicationSync); <br>
          <br>
          // deal with the error code <br>
          if (!bResult) <br>
          { <br>
          port-&gt;ProcessErrorMessage("GetOverlappedResults() in Wri <br>
          eFile()"); <br>
          <br>
          } <br>
          } // end if (!bWrite) <br>
          <br>
          // Verify that the data size send equals what we tried to send <br>
          if (BytesSent != strlen((char*)port-&gt;m_szWriteBuffer)) <br>
          { <br>
          printf("WARNING: WriteFile() error.. Bytes Sent: %d; Message Len <br>
          th: <br>
          %d\n", BytesSent, strlen((char*)port-&gt;m_szWriteBuffer)); <br>
          } <br>
          } <br>
          <br>
          // <br>
          // Character received. Inform the owner <br>
          // <br>
          void TSerialPort::ReceiveChar(TSerialPort* port, COMSTAT comstat) <br>
          { <br>
          BOOL bRead = true; <br>
          BOOL bResult = true; <br>
          DWORD dwError = 0; <br>
          DWORD BytesRead = 0; <br>
          unsigned char RXBuff; <br>
          <br>
          <br>
          for (;;) <br>
          { <br>
          // Gain ownership of the comm port critical section. <br>
          // This process guarantees no other part of this program <br>
          // is using the port object. <br>
          <br>
          EnterCriticalSection(&amp;port-&gt;m_csCommunicationSync); <br>
          <br>
          // ClearCommError() will update the COMSTAT structure and <br>
          // clear any other errors. <br>
          <br>
          bResult = ClearCommError(port-&gt;m_hComm, &amp;dwError, &amp;comstat); 
          <br>
          <br>
          LeaveCriticalSection(&amp;port-&gt;m_csCommunicationSync); <br>
          <br>
          // start forever loop. I use this type of loop because I <br>
          // do not know at runtime how many loops this will have to <br>
          // run. My solution is to start a forever loop and to <br>
          // break out of it when I have processed all of the <br>
          // data available. Be careful with this approach and <br>
          // be sure your loop will exit. <br>
          // My reasons for this are not as clear in this sample <br>
          // as it is in my production code, but I have found this <br>
          // solutiion to be the most efficient way to do this. <br>
          <br>
          if (comstat.cbInQue == 0) <br>
          { <br>
          // break out when all bytes have been read <br>
          break; <br>
          } <br>
          <br>
          EnterCriticalSection(&amp;port-&gt;m_csCommunicationSync); <br>
          <br>
          if (bRead) <br>
          { <br>
          bResult = ReadFile(port-&gt;m_hComm, // Handl <br>
          to COMM port <br>
          &amp;RXBuff, <br>
          / RX Buffer Pointer <br>
          1, <br>
          / Read one byte <br>
          &amp;BytesRead, <br>
          / Stores number of bytes read <br>
          &amp;port-&gt;m_ov); <br>
          / pointer to the m_ov structure <br>
          // deal with the error code <br>
          if (!bResult) <br>
          { <br>
          switch (dwError = GetLastError()) <br>
          { <br>
          case ERROR_IO_PENDING: <br>
          { <br>
          // asynchronous i/o is s <br>
          ill in progress <br>
          // Proceed on to GetOver <br>
          appedResults(); <br>
          bRead = false; <br>
          break; <br>
          } <br>
          default: <br>
          { <br>
          // Another error has occ <br>
          red. Process this error. <br>
          port-&gt;ProcessErrorMessag <br>
          ("ReadFile()"); <br>
          break; <br>
          } <br>
          } <br>
          } <br>
          else <br>
          { <br>
          // ReadFile() returned complete. It is not neces <br>
          ary to call GetOv <br>
          erlappedResults() <br>
          bRead = true; <br>
          } <br>
          } // close if (bRead) <br>
          <br>
          if (!bRead) <br>
          { <br>
          bRead = true; <br>
          bResult = GetOverlappedResult(port-&gt;m_hComm, // Handl <br>
          to COMM port <br>
          <br>
          <br>
          &amp;port-&gt;m_ov, // Overlapped structure <br>
          <br>
          &amp;BytesRead, // Stores number of bytes read <br>
          <br>
          true); // Wait flag <br>
          <br>
          // deal with the error code <br>
          if (!bResult) <br>
          { <br>
          port-&gt;ProcessErrorMessage("GetOverlappedResults( <br>
          in ReadFile()"); <br>
          <br>
          } <br>
          } // close if (!bRead) <br>
          <br>
          LeaveCriticalSection(&amp;port-&gt;m_csCommunicationSync); <br>
          <br>
          // notify parent that a byte was received <br>
          ::SendMessage((port-&gt;m_pOwner)-&gt;Handle, WM_COMM_RXCHAR, (WPARAM) 
          <br>
          RXB <br>
          uff, (LPARAM) port-&gt;m_nPortNr); <br>
          } // end forever loop <br>
          <br>
          } <br>
          <br>
          <br>
          // <br>
          // Write a string to the port <br>
          // <br>
          void TSerialPort::WriteToPort(char* string) <br>
          { <br>
          assert(m_hComm != 0); <br>
          <br>
          memset(m_szWriteBuffer, 0, sizeof(m_szWriteBuffer)); <br>
          strcpy(m_szWriteBuffer, string); <br>
          <br>
          // set event for write <br>
          SetEvent(m_hWriteEvent); <br>
          } <br>
          <br>
          // <br>
          // Return the device control block <br>
          // <br>
          DCB TSerialPort::GetDCB() <br>
          { <br>
          return m_dcb; <br>
          } <br>
          <br>
          <br>
          // <br>
          // Return the communication event masks <br>
          // <br>
          DWORD TSerialPort::GetCommEvents() <br>
          { <br>
          return m_dwCommEvents; <br>
          } <br>
          <br>
          // <br>
          // Return the output buffer size <br>
          // <br>
          DWORD TSerialPort::GetWriteBufferSize() <br>
          { <br>
          return m_nWriteBufferSize; <br>
          } <br>
          <br>
          //----------------------------------------------------------------
      </td>
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