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Old 10 November 2014, 16:20   #1
Anubis
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Would be possible to get cheat option in EMU?

I think it would be nice to have some sort cheat menu with option to save search/cheats per game/configuration, rather then use limited AR. Option to search memory (if bigger then 2MB) and option to save and enable/disable cheats would be great addition to one of best emulators, imho.

I know we talk about this years ago... but wonder if opinion (and will to implement it) changed at all...
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Old 11 November 2014, 13:15   #2
Toni Wilen
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Same problem: no one has invented (or found existing solution) that is good enough to handle it properly: cheat MUST keep working even when addresses change (if program uses dos loading or if memory config is different).

Easy if you know m68k and know how the code works but that should not be requirement for using cheat feature.
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Old 14 November 2014, 20:11   #3
Anubis
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So, in short - it will not happen.

Too bad, feature would be good addition to WinUAE.
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Old 15 November 2014, 06:17   #4
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Most games are already trained, what's the point of reinventing the wheel?
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Old 15 November 2014, 10:06   #5
Toni Wilen
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Quote:
Originally Posted by Hewitson View Post
Most games are already trained, what's the point of reinventing the wheel?
Thats most pointless reason for doing or not doing something.
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Old 15 November 2014, 12:57   #6
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Little explanation about problem:

What I don't accept: config specific cheats. In other words, absolute address (for example number of lives) that only works if system has exactly same config. Many games do use absolute addresses but many also don't. It needs to work, even if game is 100% system friendly and loads in "random" addresses.

What is acceptable: some kind of finger print of code that accesses (for example) address that contains number of lives. Emulator in background keeps looking for fingerprint, when it is found, address is calculated and then frozen. (frozen because it also prevents modifications by possible other parts of game code)

Not difficult but complex and boring. As usual.

Cheat Engine (Windows cheat system, open source) does use similar system but it is also really complex, it even supports scripting. Probably (really) too complex for Amiga cheat use case but it does appear to do everything I need (and much more)

(Technically you can use it for emulated game cheats too but I think thats a bit too hacky solution..)
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Old 15 November 2014, 13:00   #7
Shoonay
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There's a super-easy tool for cheating called Cheat ‘O Matic v0.99b

Attached Files
File Type: zip Cheat 'O matic 0.99b.zip (142.6 KB, 100 views)
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Old 15 November 2014, 13:09   #8
Toni Wilen
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There's a super-easy tool for cheating called Cheat ‘O Matic v0.99b
What does it have to do with this topic?
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Old 15 November 2014, 15:22   #9
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Quote:
Originally Posted by Toni Wilen View Post
Thats most pointless reason for doing or not doing something.
Sorry but I don't understand the point of implementing something that is in most cases already available.

If people wish to cheat with WHDLoad slaves then it would be more appropriate to contact the authors of those slaves.

Last edited by Hewitson; 15 November 2014 at 15:47.
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Old 15 November 2014, 16:20   #10
Toni Wilen
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OP surely knows about existing alternatives which don't solve the problem if you want some custom trainer that can be easily used by other emulator users too.

No WHDLoad author is going to bother with those either. (and probably shouldn't except for basic options). Perhaps whdload also should have separate cheat file support instead of having them slave built-in. It probably would not be that complex because whdload already knows address space of game data and code.

Anyway, the point is to have better and generic option. (Which I want to do. Has been in my "features to do " list for many years already...)
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Old 17 November 2014, 14:25   #11
Anubis
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I am not sure if you will be able to get 'not configuration specific' cheat options. I was thinking something like 'configuration string - this codes work - leave it up to cheat creator to setup each separate configuration, or something close to your default configurations from WinUAE.

I am excited you are even considering making it option in WinUAE, no matter how long it takes to wait.


@Hewitson - games that I would use this for I will not play on WHDLoad anyway. It would be use of built in HD install. Also, most of them don't have trainers...

@Shooney
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Old 17 November 2014, 21:13   #12
Toni Wilen
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Originally Posted by Anubis View Post
I am not sure if you will be able to get 'not configuration specific' cheat options. I was thinking something like 'configuration string - this codes work - leave it up to cheat creator to setup each separate configuration, or something close to your default configurations from WinUAE.
Not acceptable. None of dos loaded (relocatable) games would work even if only number of drives changes, different HD config (even single different command in startup-sequence, number of buffers, everything) would make it incompatible and so on.. Totally not acceptable. It MUST work with dos loaded and HD loaded games too. Transparently. Not just trackloaded games.
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Old 19 November 2014, 18:46   #13
Anubis
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I see what you mean. But what if you just make it searchable in session... no save option for begging?

That would be good start... - start game, search what you need, make change, save or play... once session is closed, you loose your search.
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Old 20 November 2014, 10:20   #14
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Question

How about some kind of fingerprint that determines a known position, then an offset from that to store the cheat, and allow a mask to be applied for addresses that can change?

For example, maybe the game does a subq.w #1,d0 at a vital point, but perhaps 10 bytes before that is a unique value (possibly masked) that could determine where the cheat is. If you activate that game, you scan for the unique value, and once found, can patch the game.

Code:
        moveq   #0,d0           ;$7000
        moveq   #0,d1           ;$7200
        rts                     ;$4e75
        lea     $12345,a0       ;$41f9 $0001 $2345 - changes so must be masked!
        rts                     ;$4e75
        subq    #1,d0           ;$5340
        move.w  d0,$123456      ;$33c0 $0012 $3456 - changes so must be masked!
        rts                     ;$4e75
You could store the fingerprint and mask as:

Code:
Fingerprint: $7000 $7200 $4e75 $41f9 $0000 $0000 $4e75 
   The mask: $ffff $ffff $ffff $ffff $0000 $0000 $ffff
And finally the cheat would be stored with a label like "Infinite lives", the patch data $4e71 at offset 14 from the fingerprint, and perhaps a type like one off write, rewrite value every frame or something.

It would be up to the trainer maker to identify a safe area for the fingerprint, and if it's using relative addresses, to make sure the mask eliminates those.

WWarp uses a similar thing to identify custom disk formats.
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Old 20 November 2014, 10:27   #15
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Quote:
Originally Posted by Anubis View Post
@Hewitson - games that I would use this for I will not play on WHDLoad anyway. It would be use of built in HD install. Also, most of them don't have trainers...
Can you give some examples?
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Old 20 November 2014, 17:23   #16
Anubis
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Sure: BurnTime, Civilization, Colonization,... Sometimes even run from RAM rather than from HD.

Sure, I can use AR3 if I select 2MB emulation and that is it.

For those games, even if you use WHDLoad and preload option, you need more RAM.

Happy? Hope you prove your point that nothing should be done... because you don't see reason for it...


@Codetapper - that is why nowhere in my nick said 'code'... man, you lost me there...
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Old 20 November 2014, 18:24   #17
Michael Sykes
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In a nutshell...
Real men don't need cheats.
sorry for the trouble.

And keep it up.

Last edited by Michael Sykes; 20 November 2014 at 20:44. Reason: ...no idea what I had in mind...
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Old 20 November 2014, 18:51   #18
Toni Wilen
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Quote:
Originally Posted by Codetapper View Post
And finally the cheat would be stored with a label like "Infinite lives", the patch data $4e71 at offset 14 from the fingerprint, and perhaps a type like one off write, rewrite value every frame or something.

It would be up to the trainer maker to identify a safe area for the fingerprint, and if it's using relative addresses, to make sure the mask eliminates those.
Yeah, something like that.

Also cheat data should include approximate offset so that search works instantly in "normal" use case (My plan is to keep searching very slowly, like 10-100 kilobytes/sec, in background all the time which would not really affect emulation speed). No one should care if cheat activation needs 10 seconds or so. Possibly even use usage data from CPU emulator, search only addresses that CPU has executed.

Background search is also needed to handle cases where game loads different code for different parts of game.

In hunk mode "approximate" offset would be counted from hunk number x. In this mode search only checks all loaded hunks only (=dos processes).

Normal cheats (like infinite lives/energy) should never modify code, it would use UAE debugger's memory breakpoint feature to keep memory address contents frozen or forced to some specific value.

btw, No real men or politics or other stupid topics here.
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