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CSerialPort串口类最新修正版2016-05-07

时间:2016-05-13 04:38:37      阅读:196      评论:0      收藏:0      [点我收藏+]

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这是一份优秀的串口类文件,好多的地方值得我们学习,具体在多线程,事件,自定义消息,类的封装方面等等。
Remon提供的串口类网址为: http://codeguru.earthweb.com/network/serialport.shtml
由于已经运行十几年了,原文的问答部分列出来这么多年来的问题,经过网友们的总结,补充和修改原来代码后,整理出一份相对比较完美的代码。

 

2016-05-07补充说明:

CSerialPort类地址:https://github.com/itas109/CSerialPort

CSDN下载:http://download.csdn.net/detail/itas109/9512828

 

更新内容:

  • 修复每次打开串口发送一次,当串口无应答时,需要关闭再打开或者接收完数据才能发送的问题。 解决办法:在m_hEventArray中调整m_hWriteEvent的优先级高于读的优先级。CommThread(LPVOID pParam)函数中读写的位置也调换。 参考:http://zhidao.baidu.com/link?url=RSrbPcfTZRULFFd2ziHZPBwnoXv1iCSu_Nmycb_yEw1mklT8gkoNZAkWpl3UDhk8L35DtRPo5VV5kEGpOx-Gea
  • 修复停止位在头文件中定义成1导致SetCommState报错的问题,应为1对应的停止位是1.5。UINT stopsbits = ONESTOPBIT
  • switch(stopbits)和switch(parity)增加默认情况,增强程序健壮性

 

历史更新:

First Version by Remon Spekreijse on 2000-02-08
http://www.codeguru.com/cpp/i-n/network/serialcommunications/article.php/c2483/A-communication-class-for-serial-port.htm


Second Version by mrlong on 2007-12-25
https://code.google.com/p/mycom/
* 增加 ClosePort
* 增加 WriteToPort 两个方法
* 增加 SendData 与 RecvData 方法


by liquanhai on 2011-11-04
http://blog.csdn.net/liquanhai/article/details/4955253
* 增加 ClosePort 中交出控制权,防止死锁问题


by liquanhai on 2011-11-06
http://blog.csdn.net/liquanhai/article/details/6941574
* 增加 ReceiveChar 中防止线程死锁


by viruscamp on 2013-12-04
https://github.com/viruscamp/CSerialPort
* 增加 IsOpen 判断是否打开
* 修正 InitPort 中 parity Odd Even 参数取值错误
* 修改 InitPort 中 portnr 取值范围,portnr>9 时特殊处理
* 取消对 MFC 的依赖,使用 HWND 替代 CWnd,使用 win32 thread 函数而不是 MFC 的
* 增加用户消息编号自定义,方法来自 CnComm


by itas109 on 2014-01-10
http://blog.csdn.net/itas109/article/details/18358297
* 解决COM10以上端口无法显示的问题
* 扩展可选择端口,最大值MaxSerialPortNum可以自定义
* 添加QueryKey()和Hkey2ComboBox两个方法,用于自动查询当前有效的串口号。


by liquanhai on 2014-12-18
* 增加一些处理措施,主要是对减少CPU占用率

 

/*
**	FILENAME			CSerialPort.h
**
**	PURPOSE				This class can read, write and watch one serial port.
**						It sends messages to its owner when something happends on the port
**						The class creates a thread for reading and writing so the main
**						program is not blocked.
**
**	CREATION DATE		15-09-1997
**	LAST MODIFICATION	12-11-1997
**
**	AUTHOR				Remon Spekreijse
**
**
************************************************************************************
**  author: mrlong date:2007-12-25
**
**  改进
**	1) 增加 ClosePort
**	2) 增加 WriteToPort 两个方法
**	3) 增加 SendData 与 RecvData 方法
**************************************************************************************
***************************************************************************************
**  author:liquanhai date:2011-11-06
**
**  改进
**	1) 增加 ClosePort 中交出控制权,防止死锁问题
**	2) 增加 ReceiveChar 中防止线程死锁
**************************************************************************************
***************************************************************************************
**  author:viruscamp date:2013-12-04
**
**  改进
**	1) 增加 IsOpen 判断是否打开
**	2) 修正 InitPort 中 parity Odd Even 参数取值错误
**	3) 修改 InitPort 中 portnr 取值范围,portnr>9 时特殊处理
**	4) 取消对 MFC 的依赖,使用 HWND 替代 CWnd,使用 win32 thread 函数而不是 MFC 的
**	5) 增加用户消息编号自定义,方法来自 CnComm
*************************************************************************************** 
***************************************************************************************
**  author: itas109  date:2014-01-10
**  Blog:blog.csdn.net/itas109
**
**  改进
**    1) 解决COM10以上端口无法显示的问题
**    2) 扩展可选择端口,最大值MaxSerialPortNum可以自定义
**    3) 添加QueryKey()和Hkey2ComboBox两个方法,用于自动查询当前有效的串口号。
***************************************************************************************
**  author: itas109  date:2016-05-06
**  Blog:blog.csdn.net/itas109
**
**  改进
**    1) 修复每次打开串口发送一次,当串口无应答时,需要关闭再打开或者接收完数据才能发送的问题。
**		 解决办法:在m_hEventArray中调整m_hWriteEvent的优先级高于读的优先级。CommThread(LPVOID pParam)函数中读写的位置也调换。
**		 参考:http://zhidao.baidu.com/link?url=RSrbPcfTZRULFFd2ziHZPBwnoXv1iCSu_Nmycb_yEw1mklT8gkoNZAkWpl3UDhk8L35DtRPo5VV5kEGpOx-Gea
**    2) 修复停止位在头文件中定义成1导致SetCommState报错的问题,应为1对应的停止位是1.5。UINT stopsbits = ONESTOPBIT
**    3) switch(stopbits)和switch(parity)增加默认情况,增强程序健壮性
** 
*/

#ifndef __SERIALPORT_H__
#define __SERIALPORT_H__

#ifndef WM_COMM_MSG_BASE 
	#define WM_COMM_MSG_BASE		WM_USER + 617		//!< 消息编号的基点  
#endif

#define WM_COMM_BREAK_DETECTED		WM_COMM_MSG_BASE + 1	// A break was detected on input.
#define WM_COMM_CTS_DETECTED		WM_COMM_MSG_BASE + 2	// The CTS (clear-to-send) signal changed state. 
#define WM_COMM_DSR_DETECTED		WM_COMM_MSG_BASE + 3	// The DSR (data-set-ready) signal changed state. 
#define WM_COMM_ERR_DETECTED		WM_COMM_MSG_BASE + 4	// A line-status error occurred. Line-status errors are CE_FRAME, CE_OVERRUN, and CE_RXPARITY. 
#define WM_COMM_RING_DETECTED		WM_COMM_MSG_BASE + 5	// A ring indicator was detected. 
#define WM_COMM_RLSD_DETECTED		WM_COMM_MSG_BASE + 6	// The RLSD (receive-line-signal-detect) signal changed state. 
#define WM_COMM_RXCHAR				WM_COMM_MSG_BASE + 7	// A character was received and placed in the input buffer. 
#define WM_COMM_RXFLAG_DETECTED		WM_COMM_MSG_BASE + 8	// The event character was received and placed in the input buffer.  
#define WM_COMM_TXEMPTY_DETECTED	WM_COMM_MSG_BASE + 9	// The last character in the output buffer was sent.  

#define MaxSerialPortNum 20   ///有效的串口总个数,不是串口的号 //add by itas109 2014-01-09
class CSerialPort
{														 
public:
	// contruction and destruction
	CSerialPort();
	virtual		~CSerialPort();

	// port initialisation		
	// UINT stopsbits = ONESTOPBIT   stop is index 0 = 1 1=1.5 2=2 
	// 切记:stopsbits = 1,不是停止位为1。
	// by itas109 20160506
	BOOL		InitPort(CWnd* pPortOwner, UINT portnr = 1, UINT baud = 19200, 
				char parity = 'N', UINT databits = 8, UINT stopsbits = ONESTOPBIT, 
				DWORD dwCommEvents = EV_RXCHAR | EV_CTS, UINT nBufferSize = 512,
			
				DWORD ReadIntervalTimeout = 1000,
				DWORD ReadTotalTimeoutMultiplier = 1000,
				DWORD ReadTotalTimeoutConstant = 1000,
				DWORD WriteTotalTimeoutMultiplier = 1000,
				DWORD WriteTotalTimeoutConstant = 1000);

	// start/stop comm watching
	///控制串口监视线程
	BOOL		 StartMonitoring();//开始监听
	BOOL		 RestartMonitoring();//重新监听
	BOOL		 StopMonitoring();//停止监听

	DWORD		 GetWriteBufferSize();///获取写缓冲大小
	DWORD		 GetCommEvents();///获取事件
	DCB			 GetDCB();///获取DCB

///写数据到串口
	void		WriteToPort(char* string);
	void		WriteToPort(char* string,int n); // add by mrlong 2007-12-25
	void		WriteToPort(LPCTSTR string);	 // add by mrlong 2007-12-25
    void		WriteToPort(LPCTSTR string,int n);//add by mrlong 2007-12-2
	void		WriteToPort(BYTE* Buffer, int n);// add by mrlong
	void		ClosePort();					 // add by mrlong 2007-12-2  
	BOOL		IsOpen();

	void SendData(LPCTSTR lpszData, const int nLength);   //串口发送函数 by mrlong 2008-2-15
	BOOL RecvData(LPTSTR lpszData, const int nSize);	  //串口接收函数 by mrlong 2008-2-15
	void QueryKey(HKEY hKey);///查询注册表的串口号,将值存于数组中
	void Hkey2ComboBox(CComboBox& m_PortNO);///将QueryKey查询到的串口号添加到CComboBox控件中

protected:
	// protected memberfunctions
	void		ProcessErrorMessage(char* ErrorText);///错误处理
	static DWORD WINAPI CommThread(LPVOID pParam);///线程函数
	static void	ReceiveChar(CSerialPort* port);
	static void	WriteChar(CSerialPort* port);

	// thread
	//CWinThread*			m_Thread;
	HANDLE			  m_Thread;
	BOOL                m_bIsSuspened;///thread监视线程是否挂起

	// synchronisation objects
	CRITICAL_SECTION	m_csCommunicationSync;///临界资源
	BOOL				m_bThreadAlive;///监视线程运行标志

	// handles
	HANDLE				m_hShutdownEvent;  //stop发生的事件
	HANDLE				m_hComm;		   // 串口句柄 
	HANDLE				m_hWriteEvent;	 // write

	// Event array. 
	// One element is used for each event. There are two event handles for each port.
	// A Write event and a receive character event which is located in the overlapped structure (m_ov.hEvent).
	// There is a general shutdown when the port is closed. 
	///事件数组,包括一个写事件,接收事件,关闭事件
	///一个元素用于一个事件。有两个事件线程处理端口。
	///写事件和接收字符事件位于overlapped结构体(m_ov.hEvent)中
	///当端口关闭时,有一个通用的关闭。
	HANDLE				m_hEventArray[3];

	// structures
	OVERLAPPED			m_ov;///异步I/O
	COMMTIMEOUTS		m_CommTimeouts;///超时设置
	DCB					m_dcb;///设备控制块

	// owner window
	CWnd*				m_pOwner;
	//HWND				m_pOwner;


	// misc
	UINT				m_nPortNr;		//?????
	char*				m_szWriteBuffer;///写缓冲区
	DWORD				m_dwCommEvents;
	DWORD				m_nWriteBufferSize;///写缓冲大小

	int				 m_nWriteSize;//写入字节数 //add by mrlong 2007-12-25
};

#endif __SERIALPORT_H__


 

/*
**	FILENAME			CSerialPort.cpp
**
**	PURPOSE				This class can read, write and watch one serial port.
**						It sends messages to its owner when something happends on the port
**						The class creates a thread for reading and writing so the main
**						program is not blocked.
**
**	CREATION DATE		15-09-1997
**	LAST MODIFICATION	12-11-1997
**
**	AUTHOR				Remon Spekreijse
**
**  2007-12-25 mrlong    https://code.google.com/p/mycom/
**  2011-11-06 liquanhai http://blog.csdn.net/liquanhai/article/details/6941574
**  2013-12-04 viruscamp https://github.com/viruscamp/CSerialPort
**  2014-01-10 itas109   http://blog.csdn.net/itas109
**  2014-12-18 liquanhai http://blog.csdn.net/liquanhai/article/details/6941574
**  2016-05-06 itas109   http://blog.csdn.net/itas109
*/

#include "stdafx.h"
#include "SerialPort.h"

#include <assert.h>

int m_nComArray[20];
//
// Constructor
//
CSerialPort::CSerialPort()
{
	m_hComm = NULL;

	// initialize overlapped structure members to zero
	///初始化异步结构体
	m_ov.Offset = 0;
	m_ov.OffsetHigh = 0;

	// create events
	m_ov.hEvent = NULL;
	m_hWriteEvent = NULL;
	m_hShutdownEvent = NULL;

	m_szWriteBuffer = NULL;

	m_bThreadAlive = FALSE;
	m_nWriteSize = 1;
	m_bIsSuspened = FALSE;
}

//
// Delete dynamic memory
//
CSerialPort::~CSerialPort()
{
	do
	{
		SetEvent(m_hShutdownEvent);
	} while (m_bThreadAlive);

// if the port is still opened: close it 
	if (m_hComm != NULL)
	{
		CloseHandle(m_hComm);
		m_hComm = NULL;
	}
	// Close Handles  
	if(m_hShutdownEvent!=NULL)
		CloseHandle( m_hShutdownEvent); 
	if(m_ov.hEvent!=NULL)
		CloseHandle( m_ov.hEvent ); 
	if(m_hWriteEvent!=NULL)
		CloseHandle( m_hWriteEvent ); 

	//TRACE("Thread ended\n");

	delete [] m_szWriteBuffer;
}

//
// Initialize the port. This can be port 1 to MaxSerialPortNum.
///初始化串口。只能是1-MaxSerialPortNum
//
//parity:
//  n=none
//  e=even
//  o=odd
//  m=mark
//  s=space
//data:
//  5,6,7,8
//stop:
//  1,1.5,2 
//
BOOL CSerialPort::InitPort(CWnd* pPortOwner,	// the owner (CWnd) of the port (receives message)
						   UINT  portnr,		// portnumber (1..MaxSerialPortNum)
						   UINT  baud,			// baudrate
						   char  parity,		// parity 
						   UINT  databits,		// databits 
						   UINT  stopbits,		// stopbits 
						   DWORD dwCommEvents,	// EV_RXCHAR, EV_CTS etc
						   UINT  writebuffersize,// size to the writebuffer
						   
						   DWORD   ReadIntervalTimeout,
						   DWORD   ReadTotalTimeoutMultiplier,
						   DWORD   ReadTotalTimeoutConstant,
						   DWORD   WriteTotalTimeoutMultiplier,
						   DWORD   WriteTotalTimeoutConstant )	

{
	assert(portnr > 0 && portnr < 200);
	assert(pPortOwner != NULL);

	// if the thread is alive: Kill
	if (m_bThreadAlive)
	{
		do
		{
			SetEvent(m_hShutdownEvent);
		} while (m_bThreadAlive);
		//TRACE("Thread ended\n");
	}

	// create events
	if (m_ov.hEvent != NULL)
		ResetEvent(m_ov.hEvent);
	else
		m_ov.hEvent = CreateEvent(NULL, TRUE, FALSE, NULL);

	if (m_hWriteEvent != NULL)
		ResetEvent(m_hWriteEvent);
	else
		m_hWriteEvent = CreateEvent(NULL, TRUE, FALSE, NULL);
	
	if (m_hShutdownEvent != NULL)
		ResetEvent(m_hShutdownEvent);
	else
		m_hShutdownEvent = CreateEvent(NULL, TRUE, FALSE, NULL);

	// initialize the event objects
	///事件数组初始化,设定优先级别
	m_hEventArray[0] = m_hShutdownEvent;	// highest priority
	m_hEventArray[1] = m_hWriteEvent;
	m_hEventArray[2] = m_ov.hEvent;
	

	// initialize critical section
	///初始化临界资源
	InitializeCriticalSection(&m_csCommunicationSync);
	
	// set buffersize for writing and save the owner
	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];

	
	/*
	多个线程操作相同的数据时,一般是需要按顺序访问的,否则会引导数据错乱,
	无法控制数据,变成随机变量。为解决这个问题,就需要引入互斥变量,让每
	个线程都按顺序地访问变量。这样就需要使用EnterCriticalSection和
	LeaveCriticalSection函数。
	*/
	// now it critical!
	EnterCriticalSection(&m_csCommunicationSync);

	// if the port is already opened: close it
	///串口已打开就关掉
	if (m_hComm != NULL)
	{
		CloseHandle(m_hComm);
		m_hComm = NULL;
	}

	// prepare port strings
	sprintf(szPort, "\\\\.\\COM%d", portnr);///可以显示COM10以上端口//add by itas109 2014-01-09

	// stop is index 0 = 1 1=1.5 2=2
	int mystop;
	int myparity;
	switch(stopbits)
	{
		case 0:
			mystop = ONESTOPBIT;
			break;
		case 1:
			mystop = ONE5STOPBITS;
			break;
		case 2:
			mystop = TWOSTOPBITS;
			break;
			//增加默认情况,因为stopbits=1.5时,SetCommState会报错。
			//一般的电脑串口不支持1.5停止位,这个1.5停止位似乎用在红外传输上的。
			//by itas109 20160506
		default:
			mystop = ONESTOPBIT;
			break;
	}
	myparity = 0;
	parity = toupper(parity);
	switch(parity)
	{
		case 'N':
			myparity = 0;
			break;
		case 'O':
			myparity = 1;
			break;
		case 'E':
			myparity = 2;
			break;
		case 'M':
			myparity = 3;
			break;
		case 'S':
			myparity = 4;
			break;
		//增加默认情况。
		//by itas109 20160506
		default:
			myparity = 0;
			break;
	}
	sprintf(szBaud, "baud=%d parity=%c data=%d stop=%d", baud, parity, databits, mystop);

	// get a handle to the port
	/*
	通信程序在CreateFile处指定串口设备及相关的操作属性,再返回一个句柄,
	该句柄将被用于后续的通信操作,并贯穿整个通信过程串口打开后,其属性
	被设置为默认值,根据具体需要,通过调用GetCommState(hComm,&&dcb)读取
	当前串口设备控制块DCB设置,修改后通过SetCommState(hComm,&&dcb)将其写
	入。运用ReadFile()与WriteFile()这两个API函数实现串口读写操作,若为异
	步通信方式,两函数中最后一个参数为指向OVERLAPPED结构的非空指针,在读
	写函数返回值为FALSE的情况下,调用GetLastError()函数,返回值为ERROR_IO_PENDING,
	表明I/O操作悬挂,即操作转入后台继续执行。此时,可以用WaitForSingleObject()
	来等待结束信号并设置最长等待时间
	*/
	m_hComm = CreateFile(szPort,						// communication port string (COMX)
						 GENERIC_READ | GENERIC_WRITE,	// read/write types
						 0,								// comm devices must be opened with exclusive access
						 NULL,							// no security attributes
						 OPEN_EXISTING,					// comm devices must use OPEN_EXISTING
						 FILE_FLAG_OVERLAPPED,			// Async I/O
						 0);							// template must be 0 for comm devices

	///创建失败
	if (m_hComm == INVALID_HANDLE_VALUE)
	{
		// port not found
		delete [] szPort;
		delete [] szBaud;

		return FALSE;
	}

	// set the timeout values
	///设置超时
	m_CommTimeouts.ReadIntervalTimeout		 = ReadIntervalTimeout * 1000;
	m_CommTimeouts.ReadTotalTimeoutMultiplier  = ReadTotalTimeoutMultiplier * 1000;
	m_CommTimeouts.ReadTotalTimeoutConstant	= ReadTotalTimeoutConstant * 1000;
	m_CommTimeouts.WriteTotalTimeoutMultiplier = WriteTotalTimeoutMultiplier * 1000;
	m_CommTimeouts.WriteTotalTimeoutConstant   = WriteTotalTimeoutConstant * 1000;

	// configure
	///配置
	///分别调用Windows API设置串口参数
	if (SetCommTimeouts(m_hComm, &m_CommTimeouts))///设置超时
	{						   
		/*
		若对端口数据的响应时间要求较严格,可采用事件驱动方式。
		事件驱动方式通过设置事件通知,当所希望的事件发生时,Windows
		发出该事件已发生的通知,这与DOS环境下的中断方式很相似。Windows
	    定义了9种串口通信事件,较常用的有以下三种:
			EV_RXCHAR:接收到一个字节,并放入输入缓冲区;
			EV_TXEMPTY:输出缓冲区中的最后一个字符,发送出去;
			EV_RXFLAG:接收到事件字符(DCB结构中EvtChar成员),放入输入缓冲区
		在用SetCommMask()指定了有用的事件后,应用程序可调用WaitCommEvent()来等待事
		件的发生。SetCommMask(hComm,0)可使WaitCommEvent()中止
		*/
		if (SetCommMask(m_hComm, dwCommEvents))///设置通信事件
		{
			
			if (GetCommState(m_hComm, &m_dcb))///获取当前DCB参数
			{
				m_dcb.EvtChar = 'q';
				m_dcb.fRtsControl = RTS_CONTROL_ENABLE;		// set RTS bit high!
				m_dcb.BaudRate = baud;  // add by mrlong
				m_dcb.Parity   = myparity;
				m_dcb.ByteSize = databits;
				m_dcb.StopBits = mystop;

				//if (BuildCommDCB(szBaud &m_dcb))///填写DCB结构
				//{
					if (SetCommState(m_hComm, &m_dcb))///配置DCB
						; // normal operation... continue
					else
						ProcessErrorMessage("SetCommState()");
				//}
				//else
				//	ProcessErrorMessage("BuildCommDCB()");
			}
			else
				ProcessErrorMessage("GetCommState()");
		}
		else
			ProcessErrorMessage("SetCommMask()");
	}
	else
		ProcessErrorMessage("SetCommTimeouts()");

	delete [] szPort;
	delete [] szBaud;

	// flush the port
	///终止读写并清空接收和发送
	PurgeComm(m_hComm, PURGE_RXCLEAR | PURGE_TXCLEAR | PURGE_RXABORT | PURGE_TXABORT);

	// release critical section
	///释放临界资源
	LeaveCriticalSection(&m_csCommunicationSync);

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

	return TRUE;
}

//
//  The CommThread Function.
///线程函数
///监视线程的大致流程:
///检查串口-->进入循环{WaitCommEvent(不阻塞询问)询问事件-->如果有事件来到-->到相应处理(关闭\读\写)}
//
DWORD WINAPI CSerialPort::CommThread(LPVOID pParam)
{
	// Cast the void pointer passed to the thread back to
	// a pointer of CSerialPort class
	CSerialPort *port = (CSerialPort*)pParam;
	
	// Set the status variable in the dialog class to
	// TRUE to indicate the thread is running.
	///TRUE表示线程正在运行
	port->m_bThreadAlive = TRUE;	
		
	// Misc. variables
	DWORD BytesTransfered = 0; 
	DWORD Event = 0;
	DWORD CommEvent = 0;
	DWORD dwError = 0;
	COMSTAT comstat;
	BOOL  bResult = TRUE;
		
	// Clear comm buffers at startup
	///开始时清除串口缓冲
	if (port->m_hComm)		// check if the port is opened
		PurgeComm(port->m_hComm, PURGE_RXCLEAR | PURGE_TXCLEAR | PURGE_RXABORT | PURGE_TXABORT);

	// begin forever loop.  This loop will run as long as the thread is alive.
	///只要线程存在就不断读取数据
	for (;;) 
	{ 

		// Make a call to WaitCommEvent().  This call will return immediatly
		// because our port was created as an async port (FILE_FLAG_OVERLAPPED
		// and an m_OverlappedStructerlapped structure specified).  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.  If this event handle 
		// is set to the non-signeled state, it will be set to signeled when a 
		// character arrives at the port.

		// we do this for each port!

		/*
		WaitCommEvent函数第3个参数1pOverlapped可以是一个OVERLAPPED结构的变量指针
		,也可以是NULL,当用NULL时,表示该函数是同步的,否则表示该函数是异步的。
		调用WaitCommEvent时,如果异步操作不能立即完成,会立即返回FALSE,系统在
		WaitCommEvent返回前将OVERLAPPED结构成员hEvent设为无信号状态,等到产生通信
		事件时,系统将其置有信号
		*/

		bResult = WaitCommEvent(port->m_hComm, &Event, &port->m_ov);///表示该函数是异步的
		
		if (!bResult)  
		{ 
			// If WaitCommEvent() returns FALSE, process the last error to determin
			// the reason..
			///如果WaitCommEvent返回Error为FALSE,则查询错误信息
			switch (dwError = GetLastError()) 
			{ 
			case ERROR_IO_PENDING: 	///正常情况,没有字符可读
				{ 
					// This is a normal return value if there are no bytes
					// to read at the port.
					// Do nothing and continue
					break;
				}
			case 87:///系统错误
				{
					// Under Windows NT, this value is returned for some reason.
					// I have not investigated why, but it is also a valid reply
					// Also do nothing and continue.
					break;
				}
			default:///发生其他错误,其中有串口读写中断开串口连接的错误
				{
					// All other error codes indicate a serious error has
					// occured.  Process this error.
					port->ProcessErrorMessage("WaitCommEvent()");
					break;
				}
			}
		}
		else	///WaitCommEvent()能正确返回
		{
			// If WaitCommEvent() returns TRUE, check to be sure there are
			// actually bytes in the buffer to read.  
			//
			// If you are reading more than one byte at a time from the buffer 
			// (which this program does not do) you will have the situation occur 
			// where the first byte to arrive will cause the WaitForMultipleObjects() 
			// function to stop waiting.  The WaitForMultipleObjects() function 
			// resets the event handle in m_OverlappedStruct.hEvent to the non-signelead state
			// as it returns.  
			//
			// 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)
				continue;
		}	// end if bResult

		///主等待函数,会阻塞线程
		// Main wait function.  This function will normally block the thread
		// until one of nine events occur that require action.
		///等待3个事件:关断/读/写,有一个事件发生就返回
		Event = WaitForMultipleObjects(3, ///3个事件
			port->m_hEventArray, ///事件数组
			FALSE, ///有一个事件发生就返回
			INFINITE);///超时时间

		switch (Event)
		{
		case 0:
			{
				// Shutdown event.  This is event zero so it will be
				// the higest priority and be serviced first.
				///关断事件,关闭串口
				CloseHandle(port->m_hComm);
				port->m_hComm=NULL;
			 	port->m_bThreadAlive = FALSE;
				
				// Kill this thread.  break is not needed, but makes me feel better.
				//AfxEndThread(100);
				::ExitThread(100);

				break;
			}
		case 2:	// read event 将定义的各种消息发送出去
			{
				GetCommMask(port->m_hComm, &CommEvent);
				if (CommEvent & EV_RXCHAR) //接收到字符,并置于输入缓冲区中 
					ReceiveChar(port);
				
				if (CommEvent & EV_CTS) //CTS信号状态发生变化
					::SendMessage(port->m_pOwner->m_hWnd, WM_COMM_CTS_DETECTED, (WPARAM) 0, (LPARAM) port->m_nPortNr);
				if (CommEvent & EV_RXFLAG) //接收到事件字符,并置于输入缓冲区中 
					::SendMessage(port->m_pOwner->m_hWnd, WM_COMM_RXFLAG_DETECTED, (WPARAM) 0, (LPARAM) port->m_nPortNr);
				if (CommEvent & EV_BREAK)  //输入中发生中断
					::SendMessage(port->m_pOwner->m_hWnd, WM_COMM_BREAK_DETECTED, (WPARAM) 0, (LPARAM) port->m_nPortNr);
				if (CommEvent & EV_ERR) //发生线路状态错误,线路状态错误包括CE_FRAME,CE_OVERRUN和CE_RXPARITY 
					::SendMessage(port->m_pOwner->m_hWnd, WM_COMM_ERR_DETECTED, (WPARAM) 0, (LPARAM) port->m_nPortNr);
				if (CommEvent & EV_RING) //检测到振铃指示
					::SendMessage(port->m_pOwner->m_hWnd, WM_COMM_RING_DETECTED, (WPARAM) 0, (LPARAM) port->m_nPortNr);
					
				break;
			}  
		case 1: // write event 发送数据
			{
				// Write character event from port
				WriteChar(port);
				break;
			}
		default:
			{
				AfxMessageBox("接收有问题!");
				break;
			}

		} // end switch

	} // close forever loop

	return 0;
}

//
// start comm watching
///开启监视线程
//
BOOL CSerialPort::StartMonitoring()
{
	//if (!(m_Thread = AfxBeginThread(CommThread, this)))
	if (!(m_Thread = ::CreateThread (NULL, 0, CommThread, this, 0, NULL )))
		return FALSE;
	//TRACE("Thread started\n");
	return TRUE;	
}

//
// Restart the comm thread
///复位监视线程
//
BOOL CSerialPort::RestartMonitoring()
{
	//TRACE("Thread resumed\n");
	//m_Thread->ResumeThread();
	::ResumeThread(m_Thread);
	return TRUE;	
}


//
// Suspend the comm thread
///挂起监视线程
//
BOOL CSerialPort::StopMonitoring()
{
	//TRACE("Thread suspended\n");
	//m_Thread->SuspendThread();
	::SuspendThread(m_Thread);
	return TRUE;
}


//
// If there is a error, give the right message
///如果有错误,给出提示
//
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), // Default language
		(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;
}

//
// Write a character.
//
void CSerialPort::WriteChar(CSerialPort* port)
{
	BOOL bWrite = TRUE;
	BOOL bResult = TRUE;

	DWORD BytesSent = 0;
	DWORD SendLen   = port->m_nWriteSize;
	ResetEvent(port->m_hWriteEvent);


	// Gain ownership of the critical section
	EnterCriticalSection(&port->m_csCommunicationSync);

	if (bWrite)
	{
		// Initailize variables
		port->m_ov.Offset = 0;
		port->m_ov.OffsetHigh = 0;
	 
		// Clear buffer
		PurgeComm(port->m_hComm, PURGE_RXCLEAR | PURGE_TXCLEAR | PURGE_RXABORT | PURGE_TXABORT);

		bResult = WriteFile(port->m_hComm,							// Handle to COMM Port
							port->m_szWriteBuffer,					// Pointer to message buffer in calling finction
							SendLen,	// add by mrlong
							//strlen((char*)port->m_szWriteBuffer),	// Length of message to send
							&BytesSent,								// Where to store the number of bytes sent
							&port->m_ov);							// Overlapped structure

		// deal with any error codes
		if (!bResult)  
		{
			DWORD dwError = GetLastError();
			switch (dwError)
			{
				case ERROR_IO_PENDING:
					{
						// continue to GetOverlappedResults()
						BytesSent = 0;
						bWrite = FALSE;
						break;
					}
				default:
					{
						// all other error codes
						port->ProcessErrorMessage("WriteFile()");
					}
			}
		} 
		else
		{
			LeaveCriticalSection(&port->m_csCommunicationSync);
		}
	} // end if(bWrite)

	if (!bWrite)
	{
		bWrite = TRUE;
	
		bResult = GetOverlappedResult(port->m_hComm,	// Handle to COMM port 
									  &port->m_ov,		// Overlapped structure
									  &BytesSent,		// Stores number of bytes sent
									  TRUE); 			// Wait flag

		LeaveCriticalSection(&port->m_csCommunicationSync);

		// deal with the error code 
		if (!bResult)  
		{
			port->ProcessErrorMessage("GetOverlappedResults() in WriteFile()");
		}	
	} // end if (!bWrite)

	// Verify that the data size send equals what we tried to send
	if (BytesSent != SendLen /*strlen((char*)port->m_szWriteBuffer)*/)  // add by 
	{
		//TRACE("WARNING: WriteFile() error.. Bytes Sent: %d; Message Length: %d\n", BytesSent, strlen((char*)port->m_szWriteBuffer));
	}
}

//
// Character received. Inform the owner
//
void CSerialPort::ReceiveChar(CSerialPort* port)
{
	BOOL  bRead = TRUE; 
	BOOL  bResult = TRUE;
	DWORD dwError = 0;
	DWORD BytesRead = 0;
	COMSTAT comstat;
	unsigned char RXBuff;

	for (;;) 
	{ 
		//add by liquanhai 2011-11-06  防止死锁
		if(WaitForSingleObject(port->m_hShutdownEvent,0)==WAIT_OBJECT_0)
			return;

		// Gain ownership of the comm port critical section.
		// This process guarantees no other part of this program 
		// is using the port object. 
		
		EnterCriticalSection(&port->m_csCommunicationSync);

		// ClearCommError() will update the COMSTAT structure and
		// clear any other errors.
		///更新COMSTAT
		
		bResult = ClearCommError(port->m_hComm, &dwError, &comstat);

		LeaveCriticalSection(&port->m_csCommunicationSync);

		// start forever loop.  I use this type of loop because I
		// do not know at runtime how many loops this will have to
		// run. My solution is to start a forever loop and to
		// break out of it when I have processed all of the
		// data available.  Be careful with this approach and
		// be sure your loop will exit.
		// My reasons for this are not as clear in this sample 
		// as it is in my production code, but I have found this 
		// solutiion to be the most efficient way to do this.
		
		///所有字符均被读出,中断循环
		if (comstat.cbInQue == 0)
		{
			// break out when all bytes have been read
			break;
		}
						
		EnterCriticalSection(&port->m_csCommunicationSync);

		if (bRead)
		{
			///串口读出,读出缓冲区中字节
			bResult = ReadFile(port->m_hComm,		// Handle to COMM port 
							   &RXBuff,				// RX Buffer Pointer
							   1,					// Read one byte
							   &BytesRead,			// Stores number of bytes read
							   &port->m_ov);		// pointer to the m_ov structure
			// deal with the error code 
			///若返回错误,错误处理
			if (!bResult)  
			{ 
				switch (dwError = GetLastError()) 
				{ 
					case ERROR_IO_PENDING: 	
						{ 
							// asynchronous i/o is still in progress 
							// Proceed on to GetOverlappedResults();
							///异步IO仍在进行
							bRead = FALSE;
							break;
						}
					default:
						{
							// Another error has occured.  Process this error.
							port->ProcessErrorMessage("ReadFile()");
							break;
							//return;///防止读写数据时,串口非正常断开导致死循环一直执行。add by itas109 2014-01-09 与上面liquanhai添加防死锁的代码差不多
						} 
				}
			}
			else///ReadFile返回TRUE
			{
				// ReadFile() returned complete. It is not necessary to call GetOverlappedResults()
				bRead = TRUE;
			}
		}  // close if (bRead)

		///异步IO操作仍在进行,需要调用GetOverlappedResult查询
		if (!bRead)
		{
			bRead = TRUE;
			bResult = GetOverlappedResult(port->m_hComm,	// Handle to COMM port 
										  &port->m_ov,		// Overlapped structure
										  &BytesRead,		// Stores number of bytes read
										  TRUE); 			// Wait flag

			// deal with the error code 
			if (!bResult)  
			{
				port->ProcessErrorMessage("GetOverlappedResults() in ReadFile()");
			}	
		}  // close if (!bRead)
				
		LeaveCriticalSection(&port->m_csCommunicationSync);

		// notify parent that a byte was received
		::SendMessage((port->m_pOwner->m_hWnd), WM_COMM_RXCHAR, (WPARAM) RXBuff, (LPARAM) port->m_nPortNr);
	} // end forever loop

}

//
// Write a string to the port
//
void CSerialPort::WriteToPort(char* string)
{		
	assert(m_hComm != 0);

	memset(m_szWriteBuffer, 0, sizeof(m_szWriteBuffer));
	strcpy(m_szWriteBuffer, string);
	m_nWriteSize=strlen(string); // add by mrlong
	// set event for write
	SetEvent(m_hWriteEvent);
}

//
// Return the device control block
//
DCB CSerialPort::GetDCB()
{
	return m_dcb;
}

//
// Return the communication event masks
//
DWORD CSerialPort::GetCommEvents()
{
	return m_dwCommEvents;
}

//
// Return the output buffer size
//
DWORD CSerialPort::GetWriteBufferSize()
{
	return m_nWriteBufferSize;
}

BOOL CSerialPort::IsOpen()
{
	return m_hComm != NULL;
}

void CSerialPort::ClosePort()
{
	MSG message;
	//add by liquanhai  防止死锁  2011-11-06
	do
	{
		SetEvent(m_hShutdownEvent);
		if(::PeekMessage(&message,m_pOwner->m_hWnd,0,0,PM_REMOVE))
		{
			::TranslateMessage(&message);
			::DispatchMessage(&message);
		}
	} while (m_bThreadAlive);

	// if the port is still opened: close it 
	if (m_hComm != NULL)
	{
		CloseHandle(m_hComm);
		m_hComm = NULL;
	}
	
	// Close Handles  
	if(m_hShutdownEvent!=NULL)
		ResetEvent(m_hShutdownEvent);
	if(m_ov.hEvent!=NULL)
		ResetEvent(m_ov.hEvent);
	if(m_hWriteEvent!=NULL)
		ResetEvent(m_hWriteEvent);			
		
	//delete [] m_szWriteBuffer;
	    if(m_szWriteBuffer != NULL)
    {
        delete [] m_szWriteBuffer;
        m_szWriteBuffer = NULL;
    }
	
}

void CSerialPort::WriteToPort(char* string,int n)
{
	assert(m_hComm != 0);
	memset(m_szWriteBuffer, 0, sizeof(m_szWriteBuffer));
	memcpy(m_szWriteBuffer, string, n);
	m_nWriteSize = n;

	// set event for write
	SetEvent(m_hWriteEvent);
}

void CSerialPort::WriteToPort(LPCTSTR string)
{
	assert(m_hComm != 0);
	memset(m_szWriteBuffer, 0, sizeof(m_szWriteBuffer));
	strcpy(m_szWriteBuffer, string);
	m_nWriteSize=strlen(string);
	// set event for write
	SetEvent(m_hWriteEvent);
}

void CSerialPort::WriteToPort(BYTE* Buffer, int n)
{
	assert(m_hComm != 0);
	memset(m_szWriteBuffer, 0, sizeof(m_szWriteBuffer));
	int i;
	for(i=0; i<n; i++)
	{
		m_szWriteBuffer[i] = Buffer[i];
	}
	m_nWriteSize=n;

	// set event for write
	SetEvent(m_hWriteEvent);
}


void CSerialPort::SendData(LPCTSTR lpszData, const int nLength)
{
	assert(m_hComm != 0);
	memset(m_szWriteBuffer, 0, nLength);
	strcpy(m_szWriteBuffer, lpszData);
	m_nWriteSize=nLength;
	// set event for write
	SetEvent(m_hWriteEvent);
}

BOOL CSerialPort::RecvData(LPTSTR lpszData, const int nSize)
{
	//
	//接收数据
	//
	assert(m_hComm!=0);
	memset(lpszData,0,nSize);
	DWORD mylen  = 0;
	DWORD mylen2 = 0;
	while (mylen<nSize) {
		if(!ReadFile(m_hComm,lpszData,nSize,&mylen2,NULL)) 
			return FALSE;
		mylen += mylen2;

		
	}
	
	return TRUE;
}
//
///查询注册表的串口号,将值存于数组中
///本代码参考于mingojiang的获取串口逻辑名代码
//
void CSerialPort::QueryKey(HKEY hKey) 
{ 
	#define MAX_KEY_LENGTH 255
	#define MAX_VALUE_NAME 16383
	//	TCHAR    achKey[MAX_KEY_LENGTH];   // buffer for subkey name
	//	DWORD    cbName;                   // size of name string 
	TCHAR    achClass[MAX_PATH] = TEXT("");  // buffer for class name 
	DWORD    cchClassName = MAX_PATH;  // size of class string 
	DWORD    cSubKeys=0;               // number of subkeys 
	DWORD    cbMaxSubKey;              // longest subkey size 
	DWORD    cchMaxClass;              // longest class string 
	DWORD    cValues;              // number of values for key 
	DWORD    cchMaxValue;          // longest value name 
	DWORD    cbMaxValueData;       // longest value data 
	DWORD    cbSecurityDescriptor; // size of security descriptor 
	FILETIME ftLastWriteTime;      // last write time 
	
	DWORD i, retCode; 
	
	TCHAR  achValue[MAX_VALUE_NAME]; 
	DWORD cchValue = MAX_VALUE_NAME; 
	
	// Get the class name and the value count. 
	retCode = RegQueryInfoKey(
		hKey,                    // key handle 
		achClass,                // buffer for class name 
		&cchClassName,           // size of class string 
		NULL,                    // reserved 
		&cSubKeys,               // number of subkeys 
		&cbMaxSubKey,            // longest subkey size 
		&cchMaxClass,            // longest class string 
		&cValues,                // number of values for this key 
		&cchMaxValue,            // longest value name 
		&cbMaxValueData,         // longest value data 
		&cbSecurityDescriptor,   // security descriptor 
		&ftLastWriteTime);       // last write time 
	
	for (i=0;i<20;i++)///存放串口号的数组初始化
	{
		m_nComArray[i] = -1;
	}
	
	// Enumerate the key values. 
	if (cValues > 0) {
		for (i=0, retCode=ERROR_SUCCESS; i<cValues; i++) { 
			cchValue = MAX_VALUE_NAME;  achValue[0] = '\0'; 
			if (ERROR_SUCCESS == RegEnumValue(hKey, i, achValue, &cchValue, NULL, NULL, NULL, NULL))  { 
				CString szName(achValue);
				if (-1 != szName.Find(_T("Serial")) || -1 != szName.Find(_T("VCom")) ){
					BYTE strDSName[10]; memset(strDSName, 0, 10);
					DWORD nValueType = 0, nBuffLen = 10;
					if (ERROR_SUCCESS == RegQueryValueEx(hKey, (LPCTSTR)achValue, NULL, &nValueType, strDSName, &nBuffLen)){
						int nIndex = -1;
						while(++nIndex < MaxSerialPortNum){
							if (-1 == m_nComArray[nIndex]) {
								m_nComArray[nIndex] = atoi((char*)(strDSName + 3));
								break;
							}
						}
					}
				}
			} 
		}
	}
	else{
		AfxMessageBox(_T("本机没有串口....."));
	}
	
}

void CSerialPort::Hkey2ComboBox(CComboBox& m_PortNO)
{
	HKEY hTestKey;
	bool Flag = FALSE;
	
	///仅是XP系统的注册表位置,其他系统根据实际情况做修改
	if(ERROR_SUCCESS == RegOpenKeyEx(HKEY_LOCAL_MACHINE, TEXT("HARDWARE\\DEVICEMAP\\SERIALCOMM"), 0, KEY_READ, &hTestKey) ){
		QueryKey(hTestKey);
	}
	RegCloseKey(hTestKey);
	
	int i = 0;
	m_PortNO.ResetContent();///刷新时,清空下拉列表内容
	while(i < MaxSerialPortNum && -1 != m_nComArray[i]){
		CString szCom; 
		szCom.Format(_T("COM%d"), m_nComArray[i]);
		m_PortNO.InsertString(i, szCom.GetBuffer(5));
		++i;
		Flag = TRUE;
		if (Flag)///把第一个发现的串口设为下拉列表的默认值
			m_PortNO.SetCurSel(0);
	}
	
}

 

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CSerialPort串口类最新修正版2016-05-07

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原文地址:http://blog.csdn.net/itas109/article/details/51337538

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