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