🚀 go-pugleaf

I did some test, but not very succesful so far.
It seems that WSAWaitForMultipleEvents cannot handle non-WSA-events.

To start with I tried this method on the serial port only, hoping to 
extend it to sockets later on.

Here's what I did:

int main(int argc, char* argv[])
{
	WSADATA wsaData;

	COMMTIMEOUTS CTimeout;
	DCB dcb;
	HANDLE hCom;

         DWORD EventTotal = 0;
         WSAEVENT EventArray[WSA_MAXIMUM_WAIT_EVENTS];
         OVERLAPPED PortOverlapped;

         char buff[1024];
         DWORD BytesRead;

         DWORD Index;

	DWORD Flags = 0;



	WSAStartup(MAKEWORD(2,2), &wsaData);

	hCom = CreateFile("COM2",
	                  GENERIC_READ | GENERIC_WRITE,
	                  0,
	                  NULL,
	                  OPEN_EXISTING,
	                  FILE_FLAG_OVERLAPPED,
	                  NULL);
	if (hCom == INVALID_HANDLE_VALUE) {
         	printf("CreateFile: %s\n", win_strerror(GetLastError()));
		return -1;
	}

	// configure port
	if (GetCommState(hCom, &dcb) == FALSE) {
		CloseHandle(hCom);
         	printf("GetCommState: %s\n", win_strerror(GetLastError()));
		return -1;
	}
	dcb.BaudRate = 19200;
	dcb.ByteSize = 8;
	dcb.Parity   = NOPARITY;
	dcb.StopBits = ONESTOPBIT;
	dcb.fBinary  = TRUE;
	if (SetCommState(hCom, &dcb) == FALSE) {
		CloseHandle(hCom);
         	printf("SetCommState: %s\n", win_strerror(GetLastError()));
		return -1;
	}

	if (GetCommTimeouts(hCom, &CTimeout) == FALSE) {
		CloseHandle(hCom);
         	printf("GetCommTimeouts: %s\n", win_strerror(GetLastError()));
		return -1;
	}
	CTimeout.ReadIntervalTimeout = MAXDWORD;
	CTimeout.ReadTotalTimeoutMultiplier = 0;
	CTimeout.ReadTotalTimeoutConstant = 0;
	if (SetCommTimeouts(hCom, &CTimeout) == FALSE) {
		CloseHandle(hCom);
         	printf("SetCommTimeouts: %s\n", win_strerror(GetLastError()));
		return -1;
	}
	if(SetCommMask(hCom, EV_RXCHAR) == FALSE) {
		CloseHandle(hCom);
         	printf("SetCommMask: %s\n", win_strerror(GetLastError()));
		return -1;
	}

	EventArray[EventTotal] =
         	(WSAEVENT)CreateEvent(NULL, // pointer to security attributes
                                       TRUE, // flag for manual-reset event
                                       FALSE,// flag for initial state
                                       NULL);// pointer to event-object name
	ZeroMemory(&PortOverlapped, sizeof(PortOverlapped));
         PortOverlapped.hEvent = (HANDLE)EventArray[EventTotal];
	EventTotal++;

	printf("Port init ok\n");

         BytesRead = 0;
         if (ReadFile(hCom, buff, 1, &BytesRead, &PortOverlapped) == 
FALSE) {
		printf("ReadFile: %s\n", win_strerror(GetLastError()));
         } else {
         	printf("BytesRead: %d\n", BytesRead);
         }

         for (;;) {
         	printf("WSAWaitForMultipleEvents...\n");
		Index = WSAWaitForMultipleEvents(EventTotal,
                                                  EventArray,
                                                  FALSE,
                                                  5000,
                                                  FALSE);
                 printf("Index = %d\n", Index);
         	if (Index == WSA_WAIT_FAILED) {
	                printf("WSA_WAIT_FAILED\n");
			break;
                 }

		WSAResetEvent(EventArray[Index - WSA_WAIT_EVENT_0]);

		WSAGetOverlappedResult(hCom, &PortOverlapped, &BytesRead, FALSE, &Flags);
         	printf("- BytesRead: %d\n", BytesRead);

         }

	CloseHandle(hCom);
	return 0;
}

...
...

The program output is:

Port init ok
BytesRead: 0
WSAWaitForMultipleEvents...
Index = 0
- BytesRead: 0
WSAWaitForMultipleEvents...
Index = 0
- BytesRead: 0
WSAWaitForMultipleEvents...
Index = 0
- BytesRead: 0
...

The timeout, given to WSAWaitForMultipleEvents does not seem to have any 
effect, because there is no delay in the loop.

This event-overlapped-stuff is still very dark to me, so I probably did 
a lot of things wrong here... But what?

Thanks,
Patrick

Eelke wrote:
> Patrick Rotsaert wrote:
> 
>> Sounds promising!
>> Do you know of any good examples on overlapped IO, events and such. 
>> Reading the microsoft help does not make it any easier ;-)
>>
> Most of my knowledge comes from the book Advanced Win32 Programming from 
> Microsoft Press and I also have had a course on concurrent programming 
> (thought we used NeXT for that course) so I can't give a link. I have 
> never used overlapped IO myself but I can give you a quick idea of how 
> to use Event  objects.
> 
> An event object is an object that can have two states signaled or 
> non-signaled. A thread can use wait functions on an Event object to wait 
> until the object goes into the signaled state. In case of the use of 
> events with overlapped IO and sockets windows will put the event in the 
> signalled state when certain conditions are met like the overlapped IO 
> transfer is completed or data is available for reading on a socket.
> 
> Eelke
>