Re: Ripping sound routines?

[lyricalnanoha@dosius.ath.cx (Steve Nickolas)]

Toinet wrote:
> On 8 mar, 21:08, lyricalnan...@dosius.ath.cx (Steve Nickolas) wrote:
>> Toinet wrote:
>> > On 8 mar, 14:53, lyricalnan...@dosius.ath.cx (Steve Nickolas) wrote:
>> >> This is more an experiment than anything. I'd like to isolate the
>> sound
>> >> code for the Munchers/Odell Lake games (they use the same sound
>> >> effects),
>> >> though I'm not sure where to start, there's only one reference to
>> >> $C030
>> >> in
>> >> main memory of Odell afaict, at $7FC8, and the routine it's in doesn't
>> >> seem
>> >> to be the one that generates the sounds I'm looking for. I might need
>> to
>> >> look a bit deeper.
>>
>> >> -uso.
>>
>> > - Replace AD 30 C0 or 2C 30 C0 or whatever the opcode is with a BRK
>> > opcode and see whether it is that routine that is called.
>> > - Otherwise look at $0300, short sound routines like that page.
>> > - If the sound code plays after a Hi-Res is displayed, search for
>> > $C050 as well and trace the code.
>>
>> > It reminds me of some old cracks...
>>
>> > antoine
>>
>> I used ApplePC to stuff a BRK over the $2C 30 C0 at 7FC7 (the 30 C0 I
>> found
>> with KEGS), and lo and behold it crashed into the monitor. �So I guess
>> I'd
>> need to trace around that.
>>
>> 7FC9- � �M=0A A=1D X=02 Y=01 P=30 S=EB
>> *
>>
>> Right over the graphics display. �I guess that means I'm on to
something,
>> but I'd prolly need to figure out *what* ...
>>
>> -uso.
> 
> Good.
> 
> Now, reverse boot trace:
> - go backwards from 7FC9 to 7F00 then 7E00, etc. and find a RTS
> e.g. you find a RTS at $7F51. That means a routine "may" begin at
> $7F52. Then perform a search of $7F52, you will probably find a JSR
> $7F52, etc. etc. etc. You will then find the real entry point of your
> sound routine
> 
> Feel free to send one disk image to my email address, I'd be glad to
> have a look at it.
> 
> antoine
>

xDDDDD

I was basically doing that once the glare cleared from my monitor (using
KEGS), though so far I haven't seemed to find the start yet.  7F3F and 7FAD
look like starts of routines that fall into the address in question.  I'm
seeking back about 16 bytes at a time using the GS debugger.

>ftp://ftp.apple.asimov.net/pub/apple_II/images/educational/mecc/MECC-A191-Odell%20Lake%20(v1.2-64K-1986).DSK

is the program I'm attempting to rip functions off.  I'm not good at this
kind of reverse engineering...yet! *runs*

(Have to admit though, EDM + some of your cracks have been quite helpful.  I
made my own single-file versions of Galaxian and Ms. Pac-Man with no
cracktros or defacement.)

-uso.