Re: Least Dangerous Way to Do This ?

[Petter Fryklund <petter.fryklund@atero.se>]

> > Hi Everyone
> >
> > Okay, don't laugh(or laugh too hard)
> >
> > I need to interface with automatically generated C. function pointers are 
> > represented as a pointer to a pointer to a char. This is weird but done 
> > for pointer arithmetic purposes.
> 
> It's not certain (in the real world, at least) if a function pointer and an 
> object pointer have the same representation. We treat them as completely 
> different things in our code generator, because some weird machines (in 
> particular the U2200) have very large representations for function pointers 
> (one version was 8 36-bit words!). Similarly, on the 16-bit 8086 compilers, 
> function pointers carried a segment (thus a 32-bit address), and object 
> pointers usually didn't (thus a 16-bit address).
> 
> So if you want this code to work in different environments, I'd try to avoid 
> mixing the two (as Simon suggested).
> 
>                                                   Randy.

I don't think the U2200 is weird, it is or was actually a very nice machine. Unfortunately most of the Unisys Linköping people where kicked out before we could try Ada, but we where very interested in it then. I for a while maintained the local releases of COBOL before going in to performance analysis and cache-disk simulations.

Is there any U2200 out there? comp.sys.unisys talks a lot about virtual ones.

Regards,
Petter