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From: joels@tekred.TEK.COM (Joel Swank)
Newsgroups: comp.sys.amiga
Subject: Re: CTL-C .. anybody know how to...
Message-ID: <1659@tekred.TEK.COM>
Date: Wed, 30-Sep-87 14:34:29 EDT
Article-I.D.: tekred.1659
Posted: Wed Sep 30 14:34:29 1987
Date-Received: Mon, 5-Oct-87 02:49:09 EDT
References: <8709260241.AA18897@cory.Berkeley.EDU> <2394@cbmvax.UUCP>
Organization: Tektronix Inc., Beaverton, Or.
Lines: 38

> 
> This line waits a signal from either Intuition  or the console.device.
> 
> Well, just add the SIGBREAKF_CTRL_C to the Wait(), ie
> 
> WakeUpBit= Wait((1<<window->UserPort->mp_SigBit)|(1<<consoleMsgPort.mp_SigBit)
>         |SIGBREAKF_CTRL_C);
> 
> 
> And that's all there is to it.
> 
> 			andy
> 
   That's great if you are waiting on something. But what if you are just
processing at full speed? You can to use SetSignal(0,0) to return the signal
bits. If you use Manx 3.4 you have a facility that does this. Manx
lower level IO routines call a routine "Chk_Abort". Chk_Abort does a
SetSignal and if CTRL_C is set calls the routine "_abort". You can include
your own _abort subroutine to do cleanup and an "exit(1)". If _abort
returns execution continues. So you can capture CTRL_C and ignore it.
The standard _abort displays '^C' and exits.  If the program is not doing any 
IO, you will have to insert your own call to Chk_Abort at the apropriate 
place. It only consumes about 70 usec by my measurements.
  A note: If you are using Manx and have a program that does a lot of IO
and try to do your own SetSignal to get control, it will very likely 
fail because Chk_Abort beats you to it. If you must use your own SetSignal
(to check for [DEF]) stub off Chk_Abort so that your program gets all
signals.
  There is one problem. If the CTRL_C came from the keyboard (rather than 
the BREAK command) there will be a character left in the input stream.
A getchar() in the _abort routine will take care of this problem, but
then if the CTRL_C came from BREAK _abort will hang waiting for a character.
I haven't found a way to tell if a character is there without waiting
if its not. Anybody know?

Joel Swank
Tektronix, Redmond, Oregon
joels@tekred.TEK.COM