comport.cpp
----------------------------------------------------------------------
//////////////////////////////////////////////////////////////////////
#include "ComPort.h"

class CComPort
{
public:
CComPort();
virtual ~CComPort();

void PresetComParameters(DWORD baud,BYTE databits,BYTE parity,BYTE stopbits);
BOOL OpenCom(LPCTSTR lpPortName);
BOOL CloseCom();
BOOL GetByte(LPBYTE rByte,DWORD dwMilliseconds);
BOOL PutByte(BYTE wByte);
DWORD ReadBlock(LPBYTE lpBuffer,DWORD nMax);
BOOL WriteBlock(LPBYTE lpBuffer,DWORD dwBufferLength);
BOOL GetOpenedStatus(void);

protected:
HANDLE m_hCommPort;
BOOL m_bOpened;
DWORD m_Baud;
BYTE m_DataBits;
BYTE m_Parity;
BYTE m_StopBits;
};

//////////////////////////////////////////////////////////////////////
// CComPort class: com_port
//////////////////////////////////////////////////////////////////////

CComPort com_port;

//////////////////////////////////////////////////////////////////////
// Construction/Destruction
//////////////////////////////////////////////////////////////////////

CComPort::CComPort()
{
m_bOpened = FALSE;
m_Baud = CBR_9600;
m_DataBits = 8;
m_Parity = NOPARITY;
m_StopBits = ONESTOPBIT;
}

CComPort::~CComPort()
{
CloseCom();
}

void CComPort::PresetComParameters(DWORD baud,BYTE databits,BYTE parity,BYTE stopbits)
{
m_Baud = baud;
m_DataBits = databits;
m_Parity = parity;
m_StopBits = stopbits;
}

BOOL CComPort::OpenCom(LPCTSTR lpPortName)
{
if(m_bOpened) return FALSE; // we are already opened, so OpenCom failed

BOOL fSuccess;
DCB dcb;

m_hCommPort = CreateFile(lpPortName,
GENERIC_READ | GENERIC_WRITE,
0, // exclusive access
NULL, // no security attrs
OPEN_EXISTING,
FILE_ATTRIBUTE_NORMAL,
NULL
);


if(m_hCommPort == INVALID_HANDLE_VALUE) return FALSE; // OpenCom failed

// Setup new connection:

GetCommState(m_hCommPort, &dcb);

dcb.BaudRate = m_Baud;
dcb.ByteSize = m_DataBits;
dcb.Parity = m_Parity;
dcb.StopBits = m_StopBits;
dcb.fOutxDsrFlow = 0; // we don't need handshake
dcb.fDtrControl = 0;
dcb.fOutxCtsFlow = 0;
dcb.fRtsControl = 0;
dcb.fBinary = TRUE ;
dcb.fParity = TRUE ;

fSuccess = SetCommState(m_hCommPort, &dcb);

if(!fSuccess) return FALSE; // Can't SetCommState -- OpenCom failed

PurgeComm(m_hCommPort,PURGE_TXABORT | PURGE_RXABORT |
PURGE_TXCLEAR | PURGE_RXCLEAR ); // Clean up COM port

m_bOpened = TRUE;
return TRUE; // OpenCom OK
}

BOOL CComPort::CloseCom()
{
if(m_bOpened) {
m_bOpened = FALSE ;
PurgeComm(m_hCommPort,PURGE_TXABORT | PURGE_RXABORT |
PURGE_TXCLEAR | PURGE_RXCLEAR ); // Clean up COM port
CloseHandle(m_hCommPort) ;
}
return TRUE;
}

BOOL CComPort::WriteBlock(LPBYTE lpBuffer, DWORD dwBufferLength)
{
DWORD dwBytesWritten;
BOOL bResult;

if (!m_bOpened) return FALSE; // we are not connected

bResult = WriteFile(m_hCommPort,lpBuffer,dwBufferLength,&dwBytesWritten,NULL);

if(!bResult) return FALSE;

return TRUE;
}

DWORD CComPort::ReadBlock(LPBYTE lpBuffer,DWORD nMax)
{
BOOL fReadStat ;
COMSTAT ComStat ;
DWORD dwErrorFlags;
DWORD dwLength;

if(!m_bOpened) return (DWORD)-1; // we are not connected

// get number of bytes in queue
if (ClearCommError( m_hCommPort, &dwErrorFlags, &ComStat )) {
dwLength = min( (DWORD) nMax, ComStat.cbInQue ) ;
}
else {
dwLength=0;
}

if(dwLength > 0) {
fReadStat = ReadFile(m_hCommPort,lpBuffer,dwLength,&dwLength,NULL);
if(!fReadStat) {
dwLength = 0;
ClearCommError(m_hCommPort,&dwErrorFlags,&ComStat) ;
}
}
return dwLength;
}

#define SLEEP_TIME 5

BOOL CComPort::GetByte(LPBYTE rByte,DWORD dwMilliseconds)
{
BYTE byt;
DWORD pause_cnt;

pause_cnt = dwMilliseconds/SLEEP_TIME; // we pause in SLEEP_TIME milliseconds increment
while(1) {
if(ReadBlock(&byt,1) > 0) {
*rByte = byt;
return TRUE;
}
if(pause_cnt == 0) break;
Sleep(SLEEP_TIME);
pause_cnt--;
}
return FALSE;
}

BOOL CComPort::PutByte(BYTE wByte)
{
return WriteBlock(&wByte,1);
}

BOOL CComPort::GetOpenedStatus(void)
{
return m_bOpened;
}

//////////////////////////////////////////////////////////////////////
//
// User interface routines to ComPort class
//
//////////////////////////////////////////////////////////////////////

void ComPort_PresetParameters(DWORD baud,BYTE databits,BYTE parity,BYTE stopbits)
{
com_port.PresetComParameters(baud,databits,parity,stopbits);
}

BOOL ComPort_Open(char *name)
{
return com_port.OpenCom(name);
}

void ComPort_Close(void)
{
com_port.CloseCom();
}

BOOL ComPort_PutByte(BYTE byt)
{
return com_port.PutByte(byt);
}

int ComPort_GetByte(DWORD dwMilliseconds)
{
BYTE byt;

if(com_port.GetByte(&byt,dwMilliseconds))
return byt;
else
return -1;
}

BOOL ComPort_GetOpenedStatus(void)
{
return com_port.GetOpenedStatus();
}

---------------------------------------------------------------------
//////////////////////////////////////////////////////////////////////

// ComPort.h: interface for the CComPort class.
//
//////////////////////////////////////////////////////////////////////

#if !defined(_COMPORT_H_)
#define _COMPORT_H_

#include <windows.h>

void ComPort_PresetParameters(DWORD baud,BYTE databits,BYTE parity,BYTE stopbits);
BOOL ComPort_Open(char *name);
void ComPort_Close(void);
BOOL ComPort_PutByte(BYTE byt);
int ComPort_GetByte(DWORD dwMilliseconds);
BOOL ComPort_GetOpenedStatus(void);

#endif // !defined(_COMPORT_H_)