Re: [Sdcc-user] Z180 sample project

[Philipp K. K. <pk...@sp...>]

On 27.03.2013 22:28, Masur Jonathan wrote:
> Hello,
> it really sounds incredible SDCC can do this automatically !
> What if you call a function that itself call a function that will affect 
> the bank switching ? Can SDCC detect such cases and do all the 
> bank-switching automatically ?

Well, sdcc does not do real interprocedural optimization. So unless the
function is inlined, sdcc will assume that the state of BBR is unknown
after the call. This could result in a write to BBR that is not
necessary (but the function body might be in a different .rel file, so
sdcc cannot know if the called function might change BBR; the only safe
way is to assume that the state of BBR is unknown after the call).

> This really sounds incredible. If SDCC can do all this, it's one more 
> reason to port it to the 6502 !
> 
> PS : What about interrupts that touches bank-switching ?

You should either not access banked memory in the handler, or put code
to save and restore BBR upon interrupts in your crt0.rel.

Philipp