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Author Topic: What does this mean (Snes 9x debugger)  (Read 1 times)
yugisokubodai
Guest
« on: October 25, 2010, 11:12:14 am »
Hi

I'm pretty new to the Snes9x Debugger.
My Snes game is a Lowrom one, it has dialouge 1 at $7182e ($8E982E in Snes address) and its pointer at $71216 ($8E9216 in Snes address).

I set two break point from read, one for $8E982E (the text) and one for 8E9216 (the pointer) and here is the result



At $8E9216, the debugger displays

Code:
$87/8378 A7 00    LDA [$00]       [$8E:9216]       A:9216  X:0007 Y:0001 P:eNvmxdIzc


and at $8E982E it displays

Code:
$87/B986 B7 00         LDA [$00],y[$8E:982E]   A:8E98  X:0000 Y:0000 P:eNvmxdIzc


I dont know what does these parameters mean?

Could anyone please explain?

Thank you for reading.
Nightcrawler
Guest
« Reply #1 on: October 25, 2010, 12:44:15 pm »
Quote from: yugisokubodai on October 25, 2010, 11:12:14 am

Code:
$87/8378 A7 00    LDA [$00]       [$8E:9216]       A:9216  X:0007 Y:0001 P:eNvmxdIzc

Code:
$87/B986 B7 00         LDA [$00],y[$8E:982E]   A:8E98  X:0000 Y:0000 P:eNvmxdIzc

I dont know what does these parameters mean?

Could anyone please explain?

Thank you for reading.

Your columns from left to right:

Program Counter, Current  Instruction,  Effective Address,  Accumulator Value, X Register Value, Y Register Value, processor status flags.

The debugger encountered an instruction at $87/8378 that read the effective address $8E9216, which you told it to break on. The instruction at that address is "LDA [$00]" which effectively loads your pointer value from $8E:9216. The accumulator value was $9216 (presumably it just loaded the pointer location into $00 in the previous instructions). Step the instruction and you'll see that change with the new pointer value it's going to load.

If that answer doesn't make any sense to you, you have a lot of reading to do on assembly language and general overview on how a processor works. It's more than I have time to explain in a single post.
yugisokubodai
Guest
« Reply #2 on: October 25, 2010, 04:37:00 pm »
Thank you very much for the explain. I got it now.
I'm reading the 'Programing the 65816' from the Western Center right now.
Nightcrawler
Guest
« Reply #3 on: October 26, 2010, 07:41:23 am »
Your self initiative shows promise. Smiley If you run into any specific road blocks, I'm sure myself or others would lend you a helping hand.
yugisokubodai
Guest
« Reply #4 on: October 26, 2010, 08:22:15 am »
I found this site last year, since then I was reading a lot of Rom hacking stuff. I myself succeeded in translating several games into my language, but I realized that what I had done was just merely an immitate without understanding a bit of Asm.
So I decided to start over from the beginning, the Asm 65816.
But I'm not a programmer, many concept seems to be hard to understand to me, but I'll try.

Thank you very much for the help  Smiley
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