A92: Re: Re: "Transfer" of values between C and ASM


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A92: Re: Re: "Transfer" of values between C and ASM




> > If idle_loop is properly defined you shoule be able to write:
> >
> >  int key;
> >  key = idle_loop();
> >  DrawChar(2,2,key,0);
> >
> >  or just
> >
> >  DrawChar(2,2,idle_loop(),0);
> >
> >  gcc expects data to be returned in d0 (for values) or a0 (for pointers).
>
> whoa!  that's pretty cool.  What would happen if a function returned two
> values...would l do
>  index1,index2 = function();
> or something else?

I don't know if gcc supports this with asm functions... but it would be great if
it did!

> Also, what would an example of getting a pointer returned be? (instead of a
> value, like in d0).  Thanks!

An example from Prosit:

#define List_Find prosit__0012
list_header *List_Find(list_pointer *pointer, USHORT ID);

You can now do this:
list *mylist;
...
list_header *alistitem;
alistitem = List_Find(&mylist, 42);

<alistitem> now points to the item in the list which has an ID = 42.



 / Niklas Brunlid
Check out Prosit for the TI-89 / TI-92 Plus at http://c625.sparta.lu.se
Random PQF Quote follows:

That seems to point up a significant difference between Europeans and
Americans. A European says: "I can't understand this, what's wrong with
me?" An American says: "I can't understand this, what's wrong with him?"
        -- (Terry Pratchett, alt.fan.pratchett)




References: