🚀 go-pugleaf

Neil P. wrote:

>Well, I am using overlapped I/O.  The problem is that I don't want my code
>to lock up.

It won't lock up.
WaitForSingleObject() has a timeout value.
You should be running all this an a worker thread so the GUI stays
available to the user in any case.

If you want to use blocking reads/writes instead of overlapped
(blocking is easier to write and understand), then set a reasonable
timeout with SetCommTimeouts() so you don't lock up.

>If the other unit does not respond, I want the read function to quit, but
>what is a good time to quit?

Well, you expect to get a result in < 1 sec, so 2 second timeout seems
safe.  The speed of the CPU is mostly irrelevant at 9600 baud, unless
you are talking less than 1 MHz.

	WriteFile( f, "t", 1, &written, &overlap );
	status = WaitForSingleObject( hCommEvent, 1000 );
	if( status != WAIT_OBJECT_0 )
	{	/*handle the write error*/
	}else{
		GetOverlappedResult(.....);
		/* double check the write completed */

		ReadFile( f, buf, 1, &read, &overlap );
		status = WaitForSingleObject( hCommEvent, 2000 );
		if( status != WAIT_OBJECT_0 )
		{	/*handle the read error*/
		}else{
			GetOverlappedResult(.....);
			/* double check the read */
		};
	};