Re: [cc65] DA65 GEOS Disassembly?

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From: Maciej Witkowiak (ytm_at_elysium.pl)
Date: 2003-10-10 17:25:18


Ullrich von Bassewitz dnia 10 paź 2003 o 16:38 +0200 napisał:
> So if we can come up with a general concept that covers file formats (and if
> someone explains what VLIR files are), it should be possible to add this to
> da65.

I think that Todd would want from da65 greater assistance to GEOS binary
format. Since we talk about crosstools I will write only about converted
GEOS files, the only ones that cc65 package deals with.

A .cvt file has two possible formats: sequential and vlir
SEQ:
- header: contains DOS filename/type/date/time, icon picture, load/end/start
  addresses and some strings (author, class, description)
- data: follows the header and has binary code inside, similar to PRG but
  doesn't have load address at the start

VLIR:
- much like above but has multiple data sections, information about them
  (length) is kept in a table between header and the first data section
  each such section is called a 'VLIR chain'
  System loads the first chain and executes it just like SEQ application.
  Then it is up to the program to handle data in all the other chains.
  This is similar to overlays known from Turbo Pascal I think.

In C64 world VLIR files are somewhat similar to RELs. In disk directory there
is a pointer to a sector which has 127 track/sector pairs for each of 127
possible chains. It is easy to convert it to a collection of usual SEQ/PRG
files.

Currently grc can concatenate binary files into one .cvt in VLIR format.
I don't know what is better when thinking about all supported targets - should
da65 understand .cvt format or should grc/[new tool] be able to split files
into something that da65 understands now - CBM DOS PRG-like files.

> > Lastly, I would like for DA65 to have support for GEOS address labels
> > (r0..r15, etc.) and GEOS function call labels (SetDevice, OpenDisk, etc.)
> What is wrong with just defining the necessary symbols?

They could be provided with da65 or GEOS package in some additional file so
a user doesn't have to prepare it himself. Is it ok?

ytm

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