serialport.cpp

PC端

#include "stdafx.h"
#include "SerialPort.h"
#include <assert.h>
 
//
// 构造函数
//
CSerialPort::CSerialPort()
{
	m_hComm = NULL;

	// 重叠结构成员置0
	m_ov.Offset = 0;
	m_ov.OffsetHigh = 0;

	// 创建事件
	m_ov.hEvent = NULL;
	m_hWriteEvent = NULL;
	m_hShutdownEvent = NULL;

	m_szWriteBuffer = NULL;

	m_bThreadAlive = FALSE;
}

//
// 析构函数
//
CSerialPort::~CSerialPort()
{
	do
	{
		SetEvent(m_hShutdownEvent);
	} while (m_bThreadAlive);

	TRACE("Thread ended\n");
	delete [] m_szWriteBuffer;
}

//
// 初始化串行口
//
BOOL CSerialPort::InitPort(CWnd* pPortOwner,	// 接受串行口信息的窗口
						   UINT  portnr,		// 串口数
						   UINT  baud,			// 波特率
						   char  parity,		// 奇偶 
						   UINT  databits,		// 数据位 
						   UINT  stopbits,		// 停止位 
						   DWORD dwCommEvents,	// EV_RXCHAR, EV_CTS 等
						   UINT  writebuffersize)	// 写缓冲大小
{
	assert(portnr > 0 && portnr < 5);
	assert(pPortOwner != NULL);

	// 线程是激活的则杀掉
	if (m_bThreadAlive)
	{
		do
		{
			SetEvent(m_hShutdownEvent);//设置关闭事件
		} while (m_bThreadAlive);
		TRACE("Thread ended\n");
	}

	// 建立事件
	if (m_ov.hEvent != NULL)
		ResetEvent(m_ov.hEvent); //设置事件"m_ov.hEvent"为无信号状态
	m_ov.hEvent = CreateEvent(NULL, TRUE, FALSE, NULL);

	if (m_hWriteEvent != NULL)
		ResetEvent(m_hWriteEvent);//设置事件"m_hWriteEvent"为无信号状态
	m_hWriteEvent = CreateEvent(NULL, TRUE, FALSE, NULL);
	//无继承,手动复位,无信号原始状态,无名的事件
	
	if (m_hShutdownEvent != NULL)
		ResetEvent(m_hShutdownEvent);//设置事件"m_hShutdownEvent"为无信号状态
	m_hShutdownEvent = CreateEvent(NULL, TRUE, FALSE, NULL);

	// 事件初始化
	m_hEventArray[0] = m_hShutdownEvent;	//  优先级最高
	m_hEventArray[1] = m_ov.hEvent;//
	m_hEventArray[2] = m_hWriteEvent;//写事件

	// 初始化临界区
	InitializeCriticalSection(&m_csCommunicationSync);
	
	// 设置缓冲大小和保持串口拥有者
	m_pOwner = pPortOwner;

	if (m_szWriteBuffer != NULL)
		delete [] m_szWriteBuffer;
	m_szWriteBuffer = new char[writebuffersize];

	m_nPortNr = portnr;

	m_nWriteBufferSize = writebuffersize;
	m_dwCommEvents = dwCommEvents;

	BOOL bResult = FALSE;
	char *szPort = new char[50];
	char *szBaud = new char[50];

	// 设置临界
	EnterCriticalSection(&m_csCommunicationSync);

	// 串口已打开,先关掉
	if (m_hComm != NULL)
	{
		CloseHandle(m_hComm);
		m_hComm = NULL;
	}

	// 串行口初始化
	sprintf(szPort, "COM%d", portnr);
	sprintf(szBaud, "baud=%d parity=%c data=%d stop=%d", baud, parity, databits, stopbits);

	// 获得串口句柄
	m_hComm = CreateFile(szPort,						// 串口名
				     GENERIC_READ | GENERIC_WRITE,	// 读写类型
				     0,								// 设置为独占方式
				     NULL,							// 无安全属性
				     OPEN_EXISTING,					// OPEN_EXISTING
				     FILE_FLAG_OVERLAPPED,			// 异步I/O
				     0);							// 

	if (m_hComm == INVALID_HANDLE_VALUE)
	{
		// 串口未发现
		delete [] szPort;
		delete [] szBaud;
		return FALSE;
	}

	// 设置超时值
	m_CommTimeouts.ReadIntervalTimeout = 1000;
	m_CommTimeouts.ReadTotalTimeoutMultiplier = 1000;
	m_CommTimeouts.ReadTotalTimeoutConstant = 1000;
	m_CommTimeouts.WriteTotalTimeoutMultiplier = 1000;
	m_CommTimeouts.WriteTotalTimeoutConstant = 1000;

	// 结构串口
	if (SetCommTimeouts(m_hComm, &m_CommTimeouts))
	{						   
		if (SetCommMask(m_hComm, dwCommEvents))
		{
			if (GetCommState(m_hComm, &m_dcb))
			{
				m_dcb.fRtsControl = RTS_CONTROL_ENABLE;// 设置RTS为高
				if (BuildCommDCB(szBaud, &m_dcb))
				{
					if (SetCommState(m_hComm, &m_dcb))
						; // 正常操作...继续
					else
						ProcessErrorMessage("SetCommState()");
				}
				else
					ProcessErrorMessage("BuildCommDCB()");
			}
			else
				ProcessErrorMessage("GetCommState()");
		}
		else
			ProcessErrorMessage("SetCommMask()");
	}
	else
		ProcessErrorMessage("SetCommTimeouts()");

	delete [] szPort;
	delete [] szBaud;

	// 刷新串口
	PurgeComm(m_hComm, PURGE_RXCLEAR | PURGE_TXCLEAR | PURGE_RXABORT | PURGE_TXABORT);

	// 释放临界区
	LeaveCriticalSection(&m_csCommunicationSync);

	TRACE("Initialisation for communicationport %d completed.\nUse Startmonitor to communicate.\n", portnr);

	return TRUE;
}

//
//  串口线程函数
//
UINT CSerialPort::CommThread(LPVOID pParam)
{
	// 指派一个void 指针,使其找回类 CSerialPort
	CSerialPort *port = (CSerialPort*)pParam;
	
	// 设置一状态变量为TRUE,指示线程已运行.
	port->m_bThreadAlive = TRUE;	
		
	// 其他变量
	DWORD BytesTransfered = 0; 
	DWORD Event = 0;
	DWORD CommEvent = 0;
	DWORD dwError = 0;
	COMSTAT comstat;
	BOOL  bResult = TRUE;
		
	// 开始时,清除串口缓冲区
	if (port->m_hComm)		// 检查端口是否打开
		PurgeComm(port->m_hComm, PURGE_RXCLEAR | PURGE_TXCLEAR | PURGE_RXABORT | PURGE_TXABORT);

	// 死循环,线程存在一直循环
	for (;;) 
	{ 

		// 呼叫函数 WaitCommEvent().  这种呼叫立即返回,因为异步口设置
		//为(FILE_FLAG_OVERLAPPED) m_OverlappedStructerlapped 结构被指定.
		// This call will cause the 
		// m_OverlappedStructerlapped element m_OverlappedStruct.hEvent, 
		// which is part of the m_hEventArray to 
		// be placed in a non-signeled state if there are no bytes available to be read,
		// or to a signeled state if there are bytes available.  
		// 如果事件句柄被设置为无信号状态，在串口有一个字符到来时设置为信号状态

		bResult = WaitCommEvent(port->m_hComm, &Event, &port->m_ov);

		if (!bResult)  
		{ 
			// 如果 WaitCommEvent() 返回为假, 处理错误
			switch (dwError = GetLastError()) 
			{ 
			case ERROR_IO_PENDING: 	
				{ 
					// 常返回值,指示在输入缓冲区中无字符
					break;
				}
			case 87:
				{
					// 这是NT下的返回值,此值为其他原因
					break;
				}
			default:
				{
					// 其他的错误码
					//port->ProcessErrorMessage("WaitCommEvent()");
					break;
				}
			}
		}
		else
		{
		// 如果 WaitCommEvent() 返回真值,检查在读缓冲区是否真的
		// 有输入字符,
	    //一次从缓冲区读取超过一个字符时,第一个字符到达时 会引起
		//函数WaitForMultipleObjects()停止等待,函数WaitForMultipleObjects()
		//返回时,将重置在m_OverlappedStruct.hEvent中的事件句柄为
		//无信号状态
		// If in the time between the reset of this event and the call to 
		// ReadFile() more bytes arrive, the m_OverlappedStruct.hEvent handle will be set again
		// to the signeled state. When the call to ReadFile() occurs, it will 
		// read all of the bytes from the buffer, and the program will
		// loop back around to WaitCommEvent().
		// 
		// At this point you will be in the situation where m_OverlappedStruct.hEvent is set,
		// but there are no bytes available to read.  If you proceed and call
		// ReadFile(), it will return immediatly due to the async port setup, but
		// GetOverlappedResults() will not return until the next character arrives.
		//
		// It is not desirable for the GetOverlappedResults() function to be in 
		// this state.  The thread shutdown event (event 0) and the WriteFile()
		// event (Event2) will not work if the thread is blocked by GetOverlappedResults().
		//
		// The solution to this is to check the buffer with a call to ClearCommError().
		// This call will reset the event handle, and if there are no bytes to read
		// we can loop back through WaitCommEvent() again, then proceed.
		// If there are really bytes to read, do nothing and proceed.
		
			bResult = ClearCommError(port->m_hComm, &dwError, &comstat);

			if (comstat.cbInQue == 0)//输入缓冲区无字符
				continue;
		}	// bResult结束

		// 主等待函数,等待事件发生,他正常地阻塞线程,直到要求的事件发生
		Event = WaitForMultipleObjects(3, port->m_hEventArray, FALSE, INFINITE);

		switch (Event)
		{
		case 0:
			{
				// 关闭事件.  指示0为最高的优先级,最先被服务
			 	port->m_bThreadAlive = FALSE;
				
				// 释放线程
				AfxEndThread(100);
				break;
			}
		case 1:	// 读事件
			{
				GetCommMask(port->m_hComm, &CommEvent);
				if (CommEvent & EV_CTS)
					::SendMessage(port->m_pOwner->m_hWnd, WM_COMM_CTS_DETECTED, (WPARAM) 0, (LPARAM) port->m_nPortNr);
				if (CommEvent & EV_RXFLAG)
					::SendMessage(port->m_pOwner->m_hWnd, WM_COMM_RXFLAG_DETECTED, (WPARAM) 0, (LPARAM) port->m_nPortNr);
				if (CommEvent & EV_BREAK)
					::SendMessage(port->m_pOwner->m_hWnd, WM_COMM_BREAK_DETECTED, (WPARAM) 0, (LPARAM) port->m_nPortNr);
				if (CommEvent & EV_ERR)
					::SendMessage(port->m_pOwner->m_hWnd, WM_COMM_ERR_DETECTED, (WPARAM) 0, (LPARAM) port->m_nPortNr);
				if (CommEvent & EV_RING)
					::SendMessage(port->m_pOwner->m_hWnd, WM_COMM_RING_DETECTED, (WPARAM) 0, (LPARAM) port->m_nPortNr);
				if (CommEvent & EV_RXCHAR)
					// 从串口读字符
					ReceiveChar(port, comstat);
					
				break;
			}  
		case 2: // 写事件
			{
				WriteChar(port);
				GetCommMask(port->m_hComm, &CommEvent);
				if (CommEvent & EV_TXEMPTY)
				{
					MessageBox(NULL, NULL, "完成", MB_ICONSTOP);
				}
				// 从串口写字符事件
				
				break;
			}

		} // switch 结束

	} // 关闭死循环

	return 0;
}

//
// 启动串口监测线程
//
BOOL CSerialPort::StartMonitoring()
{
	if (!(m_Thread = AfxBeginThread(CommThread, this)))
		return FALSE;
	TRACE("Thread started\n");
	return TRUE;	
}

//
// 重新启动串口线程
//
BOOL CSerialPort::RestartMonitoring()
{
	TRACE("Thread resumed\n");
	m_Thread->ResumeThread();
	return TRUE;	
}

//
//停止串口线程
//
BOOL CSerialPort::StopMonitoring()
{
	TRACE("Thread suspended\n");
	m_Thread->SuspendThread(); 
	return TRUE;	
}

//
// 显示错误信息
//
void CSerialPort::ProcessErrorMessage(char* ErrorText)
{
	char *Temp = new char[200];
	
	LPVOID lpMsgBuf;

	FormatMessage( 
		FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM,
		NULL,
		GetLastError(),
		MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), // 缺省语言
		(LPTSTR) &lpMsgBuf,
		0,
		NULL 
	);

	sprintf(Temp, "WARNING:  %s Failed with the following error: \n%s\nPort: %d\n", (char*)ErrorText, lpMsgBuf, m_nPortNr); 
	MessageBox(NULL, Temp, "Application Error", MB_ICONSTOP);

	LocalFree(lpMsgBuf);
	delete[] Temp;
}

//
// 写一个字符
//
void CSerialPort::WriteChar(CSerialPort* port)
{
	BOOL bWrite = TRUE;
	BOOL bResult = TRUE;

	DWORD BytesSent = 0;

	ResetEvent(port->m_hWriteEvent);

	// 获取临界区所有权
	EnterCriticalSection(&port->m_csCommunicationSync);

	if (bWrite)
	{
		// 变量初始化
		port->m_ov.Offset = 0;
		port->m_ov.OffsetHigh = 0;

		// 缓冲区刷新
		PurgeComm(port->m_hComm, PURGE_RXCLEAR | PURGE_TXCLEAR | PURGE_RXABORT | PURGE_TXABORT);

		bResult = WriteFile(port->m_hComm,		// 串口句柄
						port->m_szWriteBuffer,	// 写缓冲区
						strlen((char*)port->m_szWriteBuffer),// 发送大小
						&BytesSent,		// 被发送的字节
						&port->m_ov);	// 重叠结构

		// 处理错误码
		if (!bResult)  
		{
			DWORD dwError = GetLastError();
			switch (dwError)
			{
				case ERROR_IO_PENDING:
					{
						// GetOverlappedResults()函数继续
						BytesSent = 0;
						bWrite = FALSE;
						break;
					}
				default:
					{
						// 其他错误码
						port->ProcessErrorMessage("WriteFile()");
					}
			}
		} 
		else
		{
			LeaveCriticalSection(&port->m_csCommunicationSync);
		}
	} // bWrite结束

	if (!bWrite)
	{
		bWrite = TRUE;
	
		bResult = GetOverlappedResult(port->m_hComm,//串口句柄 
									  &port->m_ov,	//重叠结构
									  &BytesSent,// 发送数量
									  TRUE); 	// 等待标志

		LeaveCriticalSection(&port->m_csCommunicationSync);

		// 处理错误码 
		if (!bResult)  
		{
			port->ProcessErrorMessage("GetOverlappedResults() in WriteFile()");
		}	
	} // bWrite结束

	// 校验发送的数量与要发送的是否一致
	if (BytesSent != strlen((char*)port->m_szWriteBuffer))
	{
		TRACE("WARNING: WriteFile() error.. Bytes Sent: %d; Message Length: %d\n", BytesSent, strlen((char*)port->m_szWriteBuffer));
	}
}

//
// 字符收到,通知串口拥有者
//
void CSerialPort::ReceiveChar(CSerialPort* port, COMSTAT comstat)
{
	BOOL  bRead = TRUE; 
	BOOL  bResult = TRUE;
	DWORD dwError = 0;
	DWORD BytesRead = 0;
	unsigned char RXBuff;

	for (;;) 
	{ 
		// 获取串口临界区的所有权,保证无其他的目标使用串口 
		
		EnterCriticalSection(&port->m_csCommunicationSync);

		// ClearCommError() 更新结构 COMSTAT 清除其他的错误
		
		bResult = ClearCommError(port->m_hComm, &dwError, &comstat);

		LeaveCriticalSection(&port->m_csCommunicationSync);

		// 死循环开始,直到读取所有字符
		
		if (comstat.cbInQue == 0)
		{
			// 所有的字符读完,转出
			break;
		}
						
		EnterCriticalSection(&port->m_csCommunicationSync);

		if (bRead)
		{
			bResult = ReadFile(port->m_hComm,//端口句柄 
							   &RXBuff,		// 缓冲区
							   1,			// 读一个字符
							   &BytesRead,	// 发送数量
							   &port->m_ov);//重叠结构
			// 错误码处理 
			if (!bResult)  
			{ 
				switch (dwError = GetLastError()) 
				{ 
					case ERROR_IO_PENDING: 	
						{ 
							// 异步在操作中 
							// 继续GetOverlappedResults()处理
							bRead = FALSE;
							break;
						}
					default:
						{
							// 其他错误码
							port->ProcessErrorMessage("ReadFile()");
							break;
						} 
				}
			}
			else
			{
				// ReadFile() 操作完毕 呼叫GetOverlappedResults()
				//不一定必要
				bRead = TRUE;
			}
		}  // bRead 结束

		if (!bRead)
		{
			bRead = TRUE;
			bResult = GetOverlappedResult(port->m_hComm,//端口句柄 
										  &port->m_ov,	//重叠结构
										  &BytesRead,	// 读字符数量
										  TRUE); // 等待标志

			// 处理错误码 
			if (!bResult)  
			{
				port->ProcessErrorMessage("GetOverlappedResults() in ReadFile()");
			}	
		}  // bRead结束
				
		LeaveCriticalSection(&port->m_csCommunicationSync);

		// 通知父对象有字符收到
		::SendMessage((port->m_pOwner)->m_hWnd, WM_COMM_RXCHAR, (WPARAM) RXBuff, (LPARAM) port->m_nPortNr);
	} // 死循环结束

}

//
// 向串口写字符串
//
void CSerialPort::WriteToPort(char* string)
{		                                               
	assert(m_hComm != 0);
	memset(m_szWriteBuffer, 0, sizeof(m_szWriteBuffer));
	strcpy(m_szWriteBuffer, string);

	// 设置写事件
	SetEvent(m_hWriteEvent);
}

//
// 返回设备控制块
//
DCB CSerialPort::GetDCB()
{
	return m_dcb;
}

//
// 返回通信事件屏蔽
//
DWORD CSerialPort::GetCommEvents()
{
	return m_dwCommEvents;
}

//
// 返回写缓冲区大小
//
DWORD CSerialPort::GetWriteBufferSize()
{
	return m_nWriteBufferSize;
}