2.工程实例
下面我们用第1节所述API实现一个多线程的串口通信程序。这个例子工程（工程名为MultiThreadCom）的界面很简单，如下图所示：
它是一个多线程的应用程序，包括两个工作者线程，分别处理串口1和串口2。为了简化问题，我们让连接两个串口的电缆只包含RX、TX两根连线（即不以硬件控制RS-232，串口上只会发生EV_TXEMPTY、EV_RXCHAR事件）。
在工程实例的BOOL
CMultiThreadComApp::InitInstance()函数中，启动并设置COM1和COM2，其源代码为：
BOOL
CMultiThreadComApp::InitInstance()
{
AfxEnableControlContainer();
//打开并设置COM1
hComm1=CreateFile("COM1",
GENERIC_READ|GENERIC_WRITE, 0, NULL ,OPEN_EXISTING, 0,NULL);
if
(hComm1==(HANDLE)-1)
{
AfxMessageBox("打开COM1失败");
return
false;
}
else
{
DCB wdcb;
GetCommState
(hComm1,&wdcb);
wdcb.BaudRate=9600;
SetCommState
(hComm1,&wdcb);
PurgeComm(hComm1,PURGE_TXCLEAR);
}
//打开并设置COM2
hComm2=CreateFile("COM2",
GENERIC_READ|GENERIC_WRITE, 0, NULL ,OPEN_EXISTING, 0,NULL);
if
(hComm2==(HANDLE)-1)
{
AfxMessageBox("打开COM2失败");
return
false;
}
else
{
DCB wdcb;
GetCommState
(hComm2,&wdcb);
wdcb.BaudRate=9600;
SetCommState
(hComm2,&wdcb);
PurgeComm(hComm2,PURGE_TXCLEAR);
}
CMultiThreadComDlg
dlg;
m_pMainWnd = &dlg;
int nResponse = dlg.DoModal();
if
(nResponse == IDOK)
{
// TODO: Place code here to handle when the
dialog is
// dismissed with OK
}
else if (nResponse ==
IDCANCEL)
{
// TODO: Place code here to handle when the dialog
is
// dismissed with Cancel
}
return
FALSE;
} |
此后我们在对话框CMultiThreadComDlg的初始化函数OnInitDialog中启动两个分别处理COM1和COM2的线程：
BOOL
CMultiThreadComDlg::OnInitDialog()
{
CDialog::OnInitDialog();
// Add "About..." menu item to system menu.
// IDM_ABOUTBOX
must be in the system command range.
ASSERT((IDM_ABOUTBOX &
0xFFF0) == IDM_ABOUTBOX);
ASSERT(IDM_ABOUTBOX <
0xF000);
CMenu* pSysMenu = GetSystemMenu(FALSE);
if (pSysMenu
!= NULL)
{
CString
strAboutMenu;
strAboutMenu.LoadString(IDS_ABOUTBOX);
if
(!strAboutMenu.IsEmpty())
{
pSysMenu->AppendMenu(MF_SEPARATOR);
pSysMenu->AppendMenu(MF_STRING,
IDM_ABOUTBOX, strAboutMenu);
}
}
// Set the icon for this
dialog. The framework does this automatically
// when the
application's main window is not a dialog
SetIcon(m_hIcon, TRUE); //
Set big icon
SetIcon(m_hIcon, FALSE); // Set small icon
//
TODO: Add extra initialization here
//启动串口1处理线程
DWORD
nThreadId1;
hCommThread1 = ::CreateThread((LPSECURITY_ATTRIBUTES)NULL,
0,
(LPTHREAD_START_ROUTINE)Com1ThreadProcess,
AfxGetMainWnd()->m_hWnd, 0, &nThreadId1);
if (hCommThread1 ==
NULL)
{
AfxMessageBox("创建串口1处理线程失败");
return
false;
}
//启动串口2处理线程
DWORD nThreadId2;
hCommThread2 =
::CreateThread((LPSECURITY_ATTRIBUTES)NULL,
0,
(LPTHREAD_START_ROUTINE)Com2ThreadProcess,
AfxGetMainWnd()->m_hWnd, 0, &nThreadId2);
if (hCommThread2 ==
NULL)
{
AfxMessageBox("创建串口2处理线程失败");
return
false;
}
return TRUE; // return TRUE unless you set the focus
to a
control
} |
两个串口COM1和COM2对应的线程处理函数等待串口上发生事件，并根据事件类型和自身缓冲区是否有数据要发送进行相应的处理，其源代码为：
DWORD WINAPI Com1ThreadProcess(HWND hWnd//主窗口句柄)
{
DWORD
wEven;
char str[10]; //读入数据
SetCommMask(hComm1, EV_RXCHAR |
EV_TXEMPTY);
while (TRUE)
{
WaitCommEvent(hComm1, &wEven,
NULL);
if(wEven =
0)
{
CloseHandle(hCommThread1);
hCommThread1 =
NULL;
ExitThread(0);
}
else
{
switch
(wEven)
{
case EV_TXEMPTY:
if (wTxPos <
wTxLen)
{
//在串口1写入数据
DWORD wCount;
//写入的字节数
WriteFile(hComm1, com1Data.TxBuf[wTxPos], 1,
&wCount,
NULL);
com1Data.wTxPos++;
}
break;
case
EV_RXCHAR:
if (com1Data.wRxPos <
com1Data.wRxLen)
{
//读取串口数据, 处理收到的数据
DWORD
wCount; //读取的字节数
ReadFile(hComm1, com1Data.RxBuf[wRxPos], 1,
&wCount,
NULL);
com1Data.wRxPos++;
if(com1Data.wRxPos==
com1Data.wRxLen);
::PostMessage(hWnd, COM_SENDCHAR, 0,
1);
}
break;
}
}
}
}
return
TRUE;
}
DWORD WINAPI Com2ThreadProcess(HWND hWnd
//主窗口句柄)
{
DWORD wEven;
char str[10];
//读入数据
SetCommMask(hComm2, EV_RXCHAR | EV_TXEMPTY);
while
(TRUE)
{
WaitCommEvent(hComm2, &wEven, NULL);
if (wEven
= 0)
{
CloseHandle(hCommThread2);
hCommThread2 =
NULL;
ExitThread(0);
}
else
{
switch
(wEven)
{
case EV_TXEMPTY:
if (wTxPos <
wTxLen)
{
//在串口2写入数据
DWORD wCount;
//写入的字节数
WriteFile(hComm2, com2Data.TxBuf[wTxPos], 1,
&wCount,
NULL);
com2Data.wTxPos++;
}
break;
case
EV_RXCHAR:
if (com2Data.wRxPos <
com2Data.wRxLen)
{
//读取串口数据, 处理收到的数据
DWORD
wCount; //读取的字节数
ReadFile(hComm2, com2Data.RxBuf[wRxPos], 1,
&wCount,
NULL);
com2Data.wRxPos++;
if(com2Data.wRxPos==
com2Data.wRxLen);
::PostMessage(hWnd, COM_SENDCHAR, 0,
1);
}
break;
}
}
}
return
TRUE;
} |
线程控制函数中所操作的com1Data和com2Data是与串口对应的数据结构struct
tagSerialPort的实例，这个数据结构是：
typedef struct tagSerialPort
{
BYTE
RxBuf[SPRX_BUFLEN];//接收Buffer
WORD wRxPos; //当前接收字节位置
WORD wRxLen;
//要接收的字节数
BYTE TxBuf[SPTX_BUFLEN];//发送Buffer
WORD wTxPos;
//当前发送字节位置
WORD wTxLen; //要发送的字节数
}SerialPort, *
LPSerialPort; |
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