Cheat Engine basics - Memory Mapped file


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Main - Compatibility / Testing - Cheat Engine basics - Memory Mapped file

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dagal

Posted on 04-07-25 12:50 AM

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Hello everyone! If you are anything like me, you are used to Cheat Engine on Windows as your primary tool for game "fixing".
You may have tried Cheat Engine on melonDS and failed to find anything meaningful, banged your head a bit, and then used a search engine to arrive here!

Well, I've got what you're missing: melonDS uses a memory mapped file for the emulator different memories! And Cheat Engine doesn't search memory mapped files by default. Enabling it is very simple, just make sure that MEM_MAPPED checkbox is ticked inside "Scan Settings".

[image]

That's pretty much all you need. Credit to this post that led me to read the code until I realized what I had to be looking for: https://melonds.kuribo64.net/board/thread.php?pid=2302#2302

In addition, if you are anything like me, you will want to find an unchangeable base address for the main RAM. Sadly I couldn't find a nice comfy pointer. Reading the code, I could find a couple of paths that involve a couple of crazy offsets, which will likely change in each build. Here is how I'm getting the base address for 1.0 RC, if it's helpful to anyone:

[image]

Probably a better way to go would be to make an AOB injection on some code that accesses to this memory region to intercept this address, but I am feeling too lazy to work on that :-)

Happy hacking!

Main - Compatibility / Testing - Cheat Engine basics - Memory Mapped file

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