Path: utzoo!mnetor!uunet!husc6!cmcl2!rutgers!ames!ucbcad!ucbvax!CORY.BERKELEY.EDU!dillon
From: dillon@CORY.BERKELEY.EDU (Matt Dillon)
Newsgroups: comp.sys.amiga
Subject: Re: Need help with signals
Message-ID: <8801030156.AA04670@cory.Berkeley.EDU>
Date: 3 Jan 88 01:56:40 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Lines: 68


	Since you indicated a relative newness to programming on the Amiga
I won't rattle you on your programming style.  There are a couple of things
wrong here...

	(*) Wait() clears all waited on signals before it returns.   Wait also
	    returns a mask of all requested signals which OCCURED... this is
	    usually used before doing the more expensive GetMsg() or CheckIO()
	    calls.

	You seem to be assumming that only one signal will come back at a 
	time.  In actuality, any one, two, or all the signals may come back
	at the same time.  So if an intuition message occurs at the same time
	the serial completes, your code will never get to the serial due to
	your "ELSE IF" ... "if intuition message then to intuition stuff but
	DO NOT do serial stuff (even if serial message)" is what your code is
	doing.  It gets even worse because your console handling section is
	also on the tail end of an ELSE... 

	Fix #1:  Make each IF independant, not dangling on the previous IF's
		 else.

	Now, assumming that SerRead and ConRead are each message ports the 
	rest of the code looks correct (at least what you've given us).  In
	fact, your use of GetMsg() is one of the more interesting ways to
	check for IO completion (and remove the message from the reply port
	if the IO has completed).  In the case of the code below, it only 
	works if each request has its own reply port, which yours do.

	Most advanced programmers use only one reply port for all their 
	requests and use CheckIO()/WaitIO() instead of GetMsg().

	One addition you might want to make to the fragment below is to
	use the returned signal mask from Wait() as another IF level before
	making the more expensive GetMsg() calls:

	mask = Wait(blah)

	if ((mask & (1 << SerRead->mp_SigBit)) &&  GetMsg(SerRead)) {
	    blah
	}

					-Matt

:	while(1){
:		 Wait((1L << MyWindow->UserPort->mp_SigBit) |
:		     (1L << SerRead->mp_SigBit) |
:		     (1L << ConRead->mp_SigBit));  
:		if(WinMsg = (struct IntuiMessage *)GetMsg(MyWindow->UserPort)){
:			mclass = WinMsg->Class;
:			mcode = WinMsg->Code;
:			ReplyMsg(WinMsg);
:			if(mclass == CLOSEWINDOW){
:				AbortIO(ser_in); 
:				CloseSerial();	
:				cleanup("Exiting", 0);
:				break;
:			}
:		}
:		else if(GetMsg(SerRead)){	 <<<<<<<<<<<<<--- remove else
:			data_in = SerGetChar();
:			PutChar(data_in);
:		} 	
:		else if(GetMsg(ConRead)){	<<<<<<<<<<<<<<-- remove else
:			data_out = GetChar();
:			SerPutChar(data_out);
:		}
:	}