Path: utzoo!attcan!uunet!cs.utexas.edu!usc!ucsd!ames!lll-winken!sun-barr!newstop!sun!stpeter.Eng.Sun.COM!cmcmanis
From: cmcmanis@stpeter.Eng.Sun.COM (Chuck McManis)
Newsgroups: comp.sys.amiga.tech
Subject: Re: mixing standard i/o with intuition messages
Message-ID: <137309@sun.Eng.Sun.COM>
Date: 14 Jun 90 21:08:05 GMT
References: <3242@goanna.cs.rmit.oz.au>
Sender: news@sun.Eng.Sun.COM
Organization: Sun Microsystems, Mt. View, Ca.
Lines: 67

In article <3242@goanna.cs.rmit.oz.au> (Philip Hingston) writes:
>The subject line is basically my question: is it possible? Can I write
>a command loop which acts on intuition (or other, e.g. arexx) messages
>as well as reading lines from standard input?

You probably want something along the lines of select() in UNIX. The
answer is that it is possible, it isn't very intuitive and that is
a problem, and it isn't as easy as it should be but we will get to that
in a minute.

First, you have to realize that a single call to Wait() can wait on 
multiple signals. It does this by ORing the signals it wants to wait
for together and then checking the result to see which ones were
set. So lets say you had three message ports, IDCMP, Arexx, and I/O 
you could set it up as :
	ArexxSig = 1 << Arexxport->mp_SigBit;
	IDCMPSig = 1 << Window->UserPort->mp_SigBit;
	IOSig = 1 << MyIOport->mp_SigBit;

Then you can Wait for any port to get a signal using :
	I_got = Wait(ArexxSig | IDCMPSig | IOSig);

And you can determine which ones you got using :
	if ((I_got & ArexxSig) != 0) {
		/* Process ARexx Message(s) */
	}
	if ((I_got & IDCMPSig) != 0) {
		/* Process IDCMP Message(s) */
	}
	if ((I_got & IOSig) != 0) {
		/* Process I/O result(s) */
	}

Note carefully that you can get more than one signal set in the
result so you cannot use "else if" constructs. Also you may get
more than one message per/signal so be sure to drain the port
of all messages before you return to the Wait() call in your
loop.

(for performance conscious people the XXXSig stuff can be macros)

In the above example, what you probably want to do is to open the 
console.device and queue up IORequests to the device to read characters.
If you don't mind the overhead of dealing with one character at a time
you can use RAWKEY events. 

>A related problem: Can I set up a window in a custom screen for standard i/o?
>If so, how?

This is the second problem which is a bit tricky. What you would really
like to do is open a conhandler handle and use it that way things like
fprintf(fp,xxx) etc would work as you expect. ConMan will let you do
this by opening up "CON:w<hexaddress of window>" which can give you an
stdio FILE * handle. To do this with the standard conhandler requires
some pretty gross digging around in the global vector. The problem
with all of that is that the characters typed won't generate a signal
that you can Wait() for. If that is too much of a problem then you will
have to reinvent wheel a bit.




--
--Chuck McManis						    Sun Microsystems
uucp: {anywhere}!sun!cmcmanis   BIX: <none>   Internet: cmcmanis@Eng.Sun.COM
These opinions are my own and no one elses, but you knew that didn't you.
"I tell you this parrot is bleeding deceased!"