[Coco] os9 intercept call from C

[Walter Zambotti]

On 2020-04-19 01:03, Gene Heskett wrote:
> On Saturday 18 April 2020 12:44:08 Walter Zambotti wrote:
>
>> Opps nine characters long!!!
>>
>> Which is exactly when the Ansi front end will start converting long
>> variable names to hashes.
> What ansi front end are you refering to?

The Ansi front end that comes with the Climax C compiler.
I'm using the -A switch on cc to trigger ansi mode.

>> On 2020-04-19 00:41, Walter Zambotti wrote:
>>> That's what I have trying to say guys.
>>>
>>> The intercept function is not in the standard library as expected.
>>>
>>> At least for me if I comment out my intercept function then it fails
>>> to link with unresolved reference to intercept.
>>>
>>> Figured out what is going wrong with the missing intercept library
>>> function.
>>>
>>> An rdump shows it is in the library.
>>>
>>> The problem starts when compiling with Ansi front end.  It converts
>>> the reference to _hexvalue which I can see on the _ntbl file.
>>>
>>> Which it should not do.  Especially since 'intercept' is only 8
>>> characters long.
>>>
>>> I suppose that's another bug in the Ansi front end.
>>>
>>> I reverted the code back to K&R and it compiles and links with no
>>> problem.
>>>
>>> Thanks guys
>>>
>>> Walter
>>>
>>> On 2020-04-18 23:38, Alex Evans wrote:
>>>> Largely ignoring the fact that the above code uses ANSI syntax and
>>>> the only MW C Compiler I am aware of for the CoCo uses K&R. If you
>>>> use the provided intercept function in the library, the function to
>>>> be called is a normal C function which takes an integer as a
>>>> parameter (no RTI). If you are going to finable about directly
>>>> using F$Icpt to set you trap, it needs to return using RTI. In
>>>> addition, you need to set the pointer to the routine's storage area
>>>> in U, but in the case of the function you have provided, it does
>>>> not appear to need any storage space, so the fact you didn't set U
>>>> shouldn't be a problem.
>>>>
>>>> I would think (untested) the answer would be:
>>>> int catchall();
>>>>
>>>> int intflag=0;
>>>>
>>>> main(argc, argv)
>>>> int argc;
>>>> char *argv[];
>>>> {
>>>>   intercept(catchall);
>>>>   while (!intrlag) {
>>>>     pause();
>>>>     write(1, "*", 1);
>>>>   }
>>>> }
>>>>
>>>> catchall(sig)
>>>> int sig;
>>>> {
>>>>   intfrag=sig==0x03;
>>>> }
>>>>
>>>> If your really, really want to directly use the system call, you
>>>> need to also pull the signal number from somewhere. The routine
>>>> expexted by F$cpt is a machine code routine, and sig will probably
>>>> not be passed on the stack in the manner that MW C expects, so you
>>>> need to figure out where it would be.
>
> Cheers, Gene Heskett