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aeree
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 Posted: Thu Aug 29, 2013 6:07 pm Post subject: Calling GetAsyncKeyState , game ends up crashing |
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I tried calling GetAsyncKeyState in counter strike source using auto assembler.
The game just ends up crashing every time.
here is the code
| Code: |
push eax
push 58
call GetAsyncKeyState
pop eax
pop eax
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Geri
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| Posted: Thu Aug 29, 2013 6:21 pm Post subject: |
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Use pushfd and pushad, popfd and popad. eax is not enough, it is changing other registers and flags too.
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661089799107
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| Posted: Thu Aug 29, 2013 6:22 pm Post subject: |
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You have an extra pop eax.
| Code: |
push eax
push 58
call GetAsyncKeyState // __stdcall calling convention so stack cleanup done by the called function
pop eax
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aeree
Cheater
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| Posted: Thu Aug 29, 2013 7:09 pm Post subject: |
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| Geri wrote: | | Use pushfd and pushad, popfd and popad. eax is not enough, it is changing other registers and flags too. |
| Blacknight wrote: | You have an extra pop eax.
| Code: |
push eax
push 58
call GetAsyncKeyState // __stdcall calling convention so stack cleanup done by the called function
pop eax
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Thank you both! It seems to work now.
I didnt think that the arguements get popped off the stack once you call the function. now i feel like an idiot :s
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661089799107
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| Posted: Thu Aug 29, 2013 7:16 pm Post subject: |
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| fishbone105 wrote: |
I didnt think that the arguements get popped off the stack once you call the function. now i feel like an idiot :s |
It's not always the case. Sometimes the caller has to clean the stack. It all depends on the calling convention.
Take a look at: http://www.codeproject.com/Articles/1388/Calling-Conventions-Demystified
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Dark Byte
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| Posted: Thu Aug 29, 2013 8:04 pm Post subject: |
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and keep in mind that other registers might have been changed as well. While some registers are required to be restored on return of a function, some are not (e.g ECX if you check that link blacknight posted)
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