From: Groepaz (groepaz_at_gmx.net)
Date: 2004-01-24 02:32:40
On Saturday 24 January 2004 01:59, Benjamin Bahnsen wrote:
> > 1. Use a numeric address:
> >
> > #define c (*(unsigned char*)0xFF)
> >
> > 2. Define the variable in an assembler file, declare them as external
> > in your C file, and use #pragma zpsym("name") to import it as zeropage
> > symbol in the generated assembler module.
>
> I used the second way you described, because i want to use the variables in
> assembler, too. It works perfect, thanks. But i had to rewrite the
> memory.cfg to increase the zero page size. The default size was 1ah. I am
> not very familar with the kernal functions of the c64 and which zero page
> addresses they use. I am wondering, if it is a problem to set the zero page
> size to (for example) f0h. I am still able to use file-I/O-functions or the
> standard-I/O-functions of CC65? Or do these function use kernal calls,
> which change the zero page?
file i/o uses kernel calls yes, so you have to take care just as if you
would use them from basic (or whatever).
gpz
ps: actually some other routines, like conio, use certain zeropage locations
aswell....so you might only want to use these that are clearly marked as
"unused" in the c64 manual.
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