koreth@ssyx.ucsc.edu (Steven Grimm) (08/25/88)
Submitted-by: uunet!mcvax!philmds!leo (Leo de Wit)
Posting-number: Volume 2, Issue 47
Archive-name: break
The following program, when placed in the AUTO folder or started by hand,
lets you interrupt any program (except the desktop).
This posting consists of a manual page and a uuencoded program.
The corresponding source is sent to the moderator of comp.sources.atari.st.
For correspondence conceirning this program (bugs, questions etc.) try
L. J. M. de Wit
Nachtegaallaan 7
5731XP Mierlo
Holland
e-mail: ..!mcvax!philmds!leo
(or perhaps ..!hp4nl!philmds!leo)
----------------------------- start of manual page ----------------------------
NAME
break - stop current program on receipt of interrupt character
SYNTAX
break [-e|-d|-z] [-i|-c<code>]
DESCRIPTION
After installing break, any program can be interrupted.
This is achieved by 'extending' the existing keyboard interrupt
routine: after executing the old code the break character check
is done.
The various flags have the following meaning:
e(nable) : the current break character will end the program.
the code returned is -32, what seems to be the standard
value for programs interrupted by ^C in GEMDOS.
d(isable): no actions are done; this restores the old behaviour
z(ero) : the current break character will be discarded (made 0)
in the input buffer; this can be used to disable ^C.
i(nput) : the break character is prompted for. Combinations with
shift, control and alternate keys are also allowed.
Useful for specifying the break character interactively.
c(ode) : specifies the break character as a hexadecimal code.
The hex code must follow the 'c' flag immediately.
Useful for specifying the break character from a script.
Of the flags e,d and z only one should be used; e is the default.
Also, of the flags i and c only one should be used; control-delete is
the default. This is done on purpose; you can always change it to ^C
if you want to (or whatever key you like).
The break program can be reused indefinitely, because a next invocation
is not made memory resident; it only modifies parameters in the first
invocation (the resident one).
The program can be placed into the \AUTO folder to be installed
automatically, or activated 'by hand'. If placed in the \AUTO folder, it
should of course have a .PRG extension (break.prg); as \AUTO folder
programs don't get arguments, the break will be enabled and the break
character is control-delete in this case.
BUGS/SHORTCOMINGS
A nice extension would be the possibility to catch the interrupt from
a user program; this could be achieved by using a new trap. As this
implies restoring the old interrupt catch routine when the program
exits, and maybe also core dumps could be added to the action of an
(other) interrupt character, such a more general signal mechanism is
not added (yet). Gives me time to think of a nice implementation 8-).
JOKE
Gimme a break, huh?!
-------------- end of manual page; start of uuencoded program -----------------
begin 640 break.prg
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end