Re: [sdcc-devel] Having __far pointers that are wider than generic pointers?

[Maarten B. <sou...@ds...>]

Philipp Klaus Krause wrote on 2025-01-10 10:59:
> For the Rabbit ports, I'm considering introducing memory models where
> __far pointers are wider than generic pointers. I.e. the __far address
> space would be a superset of the generic address space.
> AFAIK, no other port currently does this. Will this cause problems?
> 
> Reasons:
> 
> The Rabbits have efficient access to a 16-bit address space. But
> acessing a wider access space needs to be done using special
> instructions. So we might want a memory model where we have efficient
> memory access by default, and only use the special instructions when
> accessing something in __far space. This is also how Dynamic C, the
> compiler provided by the Rabbit vendor, does it.
> 
> The alternative would be a mcs51-like approach, where we have __near
> pointers for access to the 16-bit address space, and any unqualified
> pointer points to __far by default. Like for mcs51, this would make
> using generic pointers less efficient.
> 
> Philipp

I believe generic pointers should be able to hold function pointers.
And I assume that this means that generic pointers can also hold far
pointers. And thus the mcs51-like approach is required.

Maarten