#: 12237 S12/OS9/68000 (OSK)
    13-Sep-91  21:23:39
Sb: #12220-#Intercepts
Fm: Bob van der Poel 76510,2203
To: Kim Kempf 71161,3221 (X)

Kim, thanks for the details on intercept routines. I'll be interested to read
your reply to Mark's query (yet another stack?). But I still don't understand
something: just when does the F$RTE get called? Surely the C compiler is not
intelligent to create my intercept function differently from any other
function--and they all end the same by doing a RTS. Oh, does the intercept
routine itself set up the stack so that the RTS branches to the F$RTE and from
there back to the program?

Yes, you are correct in that it is possible to rewrite a program to check
global flags.... but the question which has to come up is--in how many
different places should one check? And there is always the possibility that
(especially during development!) that a minor loop might be infinite and the
only way out of the *$*%**$# thing is to hit ABORT. If the intercept just sets
a flag, hitting ABORT is not going to be all the helpful. Well, I guess it
could set a global flag, and have a panic flag too which causes a exit via the
intercept if a certain number of ABORTs have been done... but for termination I
think that doing a cleanup from the intercpet and then an exit is the cleanest.

The longjmp() technique is pretty sleasy. But, again, it is a nice way to
restart to a known point (esp. in games, etc.). Again, the checking of global
flags in who knows how many places can get pretty tedious. Plus, it slows down
the response time...

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