Cheat Engine

[Kyokyonos]

So...

I recently noticed this "createthread()" function which seems way more efficient as opposed to 'hijacking' some ingame functionality to make a jump to a potentially long and time consuming (2-4 second) AA script.

I saw the 2009 thread on "createthread understanding", but still not sure how to 'safely' undo createthread().

I've made some simple AA scripts using createthread() that do some math, change values, check some conditions, or store values from addresses into some allocated addresses and it seems to work fine when I just put 'ret' at the end to return to the calling function that supposedly terminates the created thread. When I have longer scripts that involve searching/looping and a few of jumps... I try making a conditional jump to a label with 'ret' (and have tried having the conditional jump point to the main content of the script instead), but it seems to crash more often then not when the debugger gets to 'ret'. As a way around the crashing, I sometime make it loop through a long (10hr+) sleep cycle when it's done and lately have been omitting 'ret' entirely. But the concern arises if I need to re-enable the script... I assume multiple threads are created.

Is 'ret' necessary for createthread() to terminate itself? Perhaps this has something to do with my understanding of assembly ]:

[Dark Byte]

When a thread starts [esp] contains the address of ExitThread. So when the thread executes ret with a proper stack, it will call ExitThread and exit

The reason you crash is most likely a broken stack (e.g wrong parameter count when calling a function, or the wrong calling convention (cdecl requires the caller to undo the parameter pushes)

You could of course call ExitThread yourself, but this indicates that there's something wrong in your code

[Kyokyonos]

You were right! After closer inspection, there were a few inconsistencies with a few registers being pushed/popped on the stack in the code. Oops! No more crashes. Thanks!

Now I know how important the state of registers are before and after calling subroutines.