Help with investigating address

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algorithm
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Joined: Mon May 25, 2020 11:49 pm

Help with investigating address

Post by algorithm »

So, say I found an address relevant to what I want to modify.
How can I follow that addresses calls/jumps/etc.?
Or is there a way to see every other address relevant/referencing that address?

Is my assumption correct that I can simply use "step" in debug?

If that is correct, how do I go about timing it?
I find myself confused when trying to use "step", as Im unaware if what its reading back to me is relevant exactly to what Im trying to investigate?
Its also a bit awkward, for instance, what If I want to make an alteration in game and follow that alteration?
but I keep having to switch between mame window/debug window? While "stepping" its halted on an instruction, if I want to make a change in game, I have to hit f5, scramble to grab mouse, click over to mame, then click back to debug window and hit f11.
Im even a bit confused by the step terminology, like "step into" or "step over". Its unclear to me when I want to use what by their title.
If someone could clarify it would be super helpful for me.

So in that instance am I missing the window of opportunity to even view the instructions relevant?
Or is it just a matter of starting the step in the right place first try?
Also, how can I know how far to "step"?
Or is my assumption correct that I would "step" until the change has happened in game?


Another question...

If I found an instruction I wanted to look at in memory, how could I go about finding that address in memory, or disassembly?
I tried doing "find" command, but I couldnt get it to search for more than 1 byte of hex separately, so the results were muddled by single byte results all over the place, rather than the exact whole search. I tried typing it like "find 00000,fffff,FC,FF,FF,FF" and "find 00000,fffff,"FC FF FF FF" and without spaces in quotation. the only search that went through was with comma between each byte.

Thanks in advance, any wisdom or advice is very much appreciated. Im trying to learn, so any help will be great.
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Pugsy
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Re: Help with investigating address

Post by Pugsy »

Give me a specific game and addresses of what you are trying to do....I personally don't have much need to use the step functionality apart from some single stepping very occasionally, TRACE and breakpoints and watchpoints are my go to methods.

As regards find you can specify the size of the data by precede it with b. or w. or d. or q. to determine the size< you can often just do the first value if the others are the same....but you have to be careful with small values that might not be taken as hex so you can precede them with 0x.

Code: Select all

f 0,ffffff,b.12,34,56,78,de,ad,be,ef
f 0,ffffff,w.1234,5678,dead,beef
f 0,ffffff,d.12345678,deadbeef
f 0,ffffff,q.12345678deadbeef
Just type "help find" in the debugger for more info
Pugsy

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