#include "CSerial.h"

CSerial::CSerial(void){
	m_bOpened = false;
}
CSerial::~CSerial(void){
}

BOOL CSerial::Open(int nPort,int nBaud )
{
	if( m_bOpened ) return( TRUE );

	char szPort[15];
	DCB dcb;

	wsprintf( szPort, "COM%d", nPort );
	m_hComDev = CreateFile( szPort, GENERIC_READ | GENERIC_WRITE, 0, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL | FILE_FLAG_OVERLAPPED, NULL );
//CreateFile用指定的方式打開指定的串口
//m_hCom為文件句柄。
//GENERIC_READ | GENERIC_WRITE指定可以對串口進行讀寫操作。
//參數0表示串口為獨占打開。
//OPEN_EXISTING當指定串口不存在時，返回失敗。
//FILE_ATTRIBUTE_NORMAL | FILE_FLAG_OVERLAPPED表示文件屬性。
//打開串口時，須指定 FILE_FLAG_OVERLAPPED，表示文件或設備不會維護訪問指針，
//在讀寫時，須使用OVERLAPPED 結構指定訪問的文件偏移量。
	if( m_hComDev == NULL ) return( FALSE );

	memset( &m_OverlappedRead, 0, sizeof( OVERLAPPED ) );
	memset( &m_OverlappedWrite, 0, sizeof( OVERLAPPED ) );
//COMMTIMEOUTS:串口超時參數設置
	COMMTIMEOUTS CommTimeOuts;
	CommTimeOuts.ReadIntervalTimeout = 0xFFFFFFFF;
	//ReadIntervalTimeout：兩字符之間最大的延時，當讀取串口數據時，
	//一旦兩個字符傳輸的時間差超過該時間，讀取函數將返回現有的數據。
	//設置為0表示該參數不起作用。

	CommTimeOuts.ReadTotalTimeoutMultiplier = 0;//讀取每字符間的超時。
	CommTimeOuts.ReadTotalTimeoutConstant = 0;//一次讀取串口數據的固定超時。
	CommTimeOuts.WriteTotalTimeoutMultiplier = 0;//寫入每字符間的超時。
	CommTimeOuts.WriteTotalTimeoutConstant = 5000;//一次寫入串口數據的固定超時。
	SetCommTimeouts( m_hComDev, &CommTimeOuts );
//SetCommTimeouts函數設置某設備句柄的超時參數，要得到某設備句柄的超時參數可以用GetCommTimeouts函數

	m_OverlappedRead.hEvent = CreateEvent( NULL, TRUE, FALSE, NULL );
	m_OverlappedWrite.hEvent = CreateEvent( NULL, TRUE, FALSE, NULL );
//DCB:串口參數設置
	dcb.DCBlength = sizeof( DCB );
	GetCommState( m_hComDev, &dcb );
	dcb.BaudRate = nBaud;//串口的通訊速度。如為9600
	dcb.ByteSize = 8;//字節位數
	if( !SetCommState( m_hComDev, &dcb ) ||
	!SetupComm( m_hComDev, 10000, 10000 ) ||//設置串口輸入、輸出緩沖區
	m_OverlappedRead.hEvent == NULL ||
	m_OverlappedWrite.hEvent == NULL ){
		DWORD dwError = GetLastError();
		if( m_OverlappedRead.hEvent != NULL ) CloseHandle( m_OverlappedRead.hEvent );
		if( m_OverlappedWrite.hEvent != NULL ) CloseHandle( m_OverlappedWrite.hEvent );
		CloseHandle( m_hComDev );
		return FALSE;
	}

	m_bOpened = TRUE;

	return m_bOpened;

}

int CSerial::InBufferCount( void )
{

	if( !m_bOpened || m_hComDev == NULL ) return( 0 );

	DWORD dwErrorFlags;
	COMSTAT ComStat;

	ClearCommError( m_hIDComDev, &dwErrorFlags, &ComStat );

	return (int)ComStat.cbInQue;

}

DWORD CSerial::ReadData( void *buffer, DWORD dwBytesRead)
{

	if( !m_bOpened || m_hComDev == NULL ) return 0;

	BOOL bReadStatus;
	DWORD dwErrorFlags;
	COMSTAT ComStat;

	ClearCommError( m_hComDev, &dwErrorFlags, &ComStat );
	if( !ComStat.cbInQue ) return 0;

	dwBytesRead = min(dwBytesRead,(DWORD) ComStat.cbInQue);
    //ReadFile：讀取串口數據
	bReadStatus = ReadFile( m_hComDev, buffer, dwBytesRead, &dwBytesRead, &m_OverlappedRead );
	if( !bReadStatus ){
		if( GetLastError() == ERROR_IO_PENDING ){
			WaitForSingleObject( m_OverlappedRead.hEvent, 2000 );
			return dwBytesRead;
		}
		return 0;
	}

	return dwBytesRead;

}

DWORD CSerial::SendData( const char *buffer, DWORD dwBytesWritten)
{

	if( !m_bOpened || m_hComDev == NULL ) return( 0 );

	BOOL bWriteStat;
//WriteFile：向串口寫數據
	bWriteStat = WriteFile( m_hComDev, buffer, dwBytesWritten, &dwBytesWritten, &m_OverlappedWrite );
	if( !bWriteStat){
		if ( GetLastError() == ERROR_IO_PENDING ) {
			WaitForSingleObject( m_OverlappedWrite.hEvent, 1000 );
			return dwBytesWritten;
		}
		return 0;
	}
	return dwBytesWritten;

}
//CloseHandle：關閉串口
void CSerial::Close(){
	if(m_hComDev!=NULL){
		if( m_OverlappedRead.hEvent != NULL ) CloseHandle( m_OverlappedRead.hEvent );
		if( m_OverlappedWrite.hEvent != NULL ) CloseHandle( m_OverlappedWrite.hEvent );
		CloseHandle( m_hComDev );
	}
}