Re: [cc65] Problems with Atari zeropage variables

From: Greg King <>
Date: 2005-07-23 06:06:54
From: Maciej Witkowiak; on Date: July 22, 2005, at 07:02 PM -0400
> Greg King dnia 22 lip 2005 o 15:26 -0400 napisal:
> > I think that it's backwards!  I think that the compiler's pseudo-
> > registers should be the objects that are put into a specially named
> > segment (.segment "CC65ZP":zp).  Then, .zeropage can be used for
> > whatever other zero-page variables a programmer wants to put into
> > a library or program -- ".zeropage" is easier for us to remember than
> > the spelling of some special name.
> Isn't that because ".zeropage" is for user and his asm programs,
> while "EXTZP" is for standard library? Then, it would be a bug
> in the library to use ".zeropage".

It would be a bug only if those library variables were used by loadable
modules.  Then, their addresses would need to be guaranteed.  But, if they
were not used by any modules, then it wouldn't matter where they sat.  So,
it wouldn't matter whether those variables were linked before a user's
program variables, or after those program variables -- all of them could be
put into ".zeropage".

However, we can't predict what variables might be needed by future loadable
modules!  So, I guess that we need three zero-page segments:  a named one
for the compiler, a named one for the library, and ".zeropage" for
programmers' general use.
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Received on Sat Jul 23 06:53:25 2005

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