Cheat Engine

Geri · Moderator Reputation: 111 Joined: 05 Feb 2010 Posts: 5627

This idea was in my head for a long time and others have mentioned it too so I think I am not the only one who may think that this is useful, that's why I put it here for discussion.

So the feature that I am suggesting would be similar to "find out what addresses are accessed by this code" but not with a memory address, just with a register. Eg. I would like to know that for a certain code, what were the values for EAX or any other register. It isn't rare that I am using a register to calculate a memory address even if it is not accessing to the specific address itself and it is important to know that the register is not changing it's value etc. I can check it manually anytime or I can write an AA script to log the registers in an allocated space but if it is possible to do it with the debugger too, then why not? I think it would be a useful feature.

Dark Byte · Posted: Wed Oct 12, 2011 10:28 am Post subject:

So basically "find out what addresses are accessed by this code" but then also keep a record of every time it is called instead of only the first time

Is it ok if I add that as a rightclick option on a specific address so it only does it on the selected address or do you want that option from the get go? (set enabled in ce's settings)

It WILL eat up memory, especially if it's one of those instructions that get called 5000 times a second. (at least 20MB/sec ram if stack is stored too)

Geri · Moderator Reputation: 111 Joined: 05 Feb 2010 Posts: 5627

I know that CE is logging the registers on firts hit and I was thinking that storing all logs with registers + stack snapshot is gigantic but if you can add that, people can still consider using it as it is useful in some situations.

What I was thinking is a bit simplified version. When you click on a code, it will not log anything, just the selected register. Eg. "find out the values of EAX register on this code". Then it could make a similar list as with the memory addresses, but instead of logging the address + value, it will log the selected register's value only.

For example a list like EAX had the value of:

00445564 12 times
00678918 10 times
0078456C 28 times

This way the user would have a clue that the selected code and the register is suitable for calculating an address or the register is changing it's value all the time on that code. I think you could throw away every other data to not consume too much space.

And since not every code is accessing to an address, maybe it could work on any code (with a hardware breakpoint on the specific code) not just on codes that are accessing to addresses. I don't know if you have to use the same type of exception handling etc if you log a register or trying to find an accessed address so I have no idea if it is different or the same.

I was thinking about writing an AA script like
1. allocate space
2. read a register
3. make a few compares to see if the register was logged already
4. if it is in the list, continue
5. if it is not, add it to the list

Maybe I could even add some kind of counter, for example if the register was logged with that value already, increase a counter value with 1.
It would work I guess, but I would have to re-shape the template every time to apply it to the specific code and the choosen register I want to log and I have no clue how to make it user friendly.

(Btw. I have opened this topic because 2 other people independently from me had the same idea, so I though that maybe we can discuss it here as it seems to be a common suggestion.)

And if it requires lot of work, just dump the idea because I can do it with script or doing it manually, but everyone likes the automatic debugging features and I thought this can be done with a small change only, adding an option to log the register instead of the memory address.

Dark Byte · Posted: Thu Oct 13, 2011 6:40 am Post subject:

Oh ok, when I get time I'll look into it. (There is currently a lot to work on in ce so some stuff might be shifted to 6.3)

Also, as for doing it yourself, if you're really bored and have a lot of time on your hands(and i mean, REALLY bored), you could learn lua, then program it so it adds that option to the (context)menu in the memoryview form.
And in that function you set an onExecute breakpoint on the currently selected address and then handle the breakpoints with lua, recording and automatically continuing.
It might not be as fast as native code, but it would be userfriendly enough

Geri · Moderator Reputation: 111 Joined: 05 Feb 2010 Posts: 5627

Yes, good idea. I can use the debugger with lua too. And it never hurts to learn something new, only the time pressure is problem. And it is not so important for me so take your time if you plan to add it. I can solve it fairly quickly with scripts too. Writing a short script to see if the register is always fix or changing is taking a minute only.

EDIT:
For those who care about it, I have posted a simple AA script just to check that the register has fix or not fix value. Maybe later I will make one that is logging more than 1 value but usually all I care about is that the value is fix or not.

http://forum.cheatengine.org/viewtopic.php?t=543655

atom0s · Posted: Fri Oct 14, 2011 3:12 pm Post subject:

Hey Geri try this out; if you have the latest Alpha of CE6.2, add this script to your autorun folder. Just name it regrecord.lua:

Geri · Moderator Reputation: 111 Joined: 05 Feb 2010 Posts: 5627

Pretty cool. It has worked well for me. Much more user friendly than my shitty AA script. If 6.2 gamma comes out, this should be stickied somewhere so people can find it and use it.

atom0s · Posted: Sun Nov 13, 2011 9:32 pm Post subject:

Repost

Here is v2 of the script above since the forums got nuked: