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A little help?

 
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GaiaOrochi
How do I cheat?
Reputation: 0

Joined: 08 Nov 2015
Posts: 7
PostPosted: Tue Mar 29, 2016 4:47 am    Post subject: A little help? Reply with quote
Idk what to do to change fstp thingy...edi is the value i want to change but mov edi will crash the game?
Code:
fstp qword ptr [edi]
  push eax
  mov eax,9999
  add [edi],eax
  pop edi
  pop eax
  pop esi
  pop ebp
  jmp return
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ulysse31
Master Cheater
Reputation: 2

Joined: 19 Mar 2015
Posts: 324
Location: Paris
PostPosted: Tue Mar 29, 2016 6:23 am    Post subject: Reply with quote
Quote:
The FST instruction copies the value in the ST(0) register to the destination operand, which can be a memory location or another register in the FPU register stack. When storing the value in memory, the value is converted to single-precision or double-precision floating-point format.
The FSTP instruction performs the same operation as the FST instruction and then pops the register stack. To pop the register stack, the processor marks the ST(0) register as empty and increments the stack pointer (TOP) by 1. The FSTP instruction can also store values in memory in double extended-precision floating-point format.


Therefore in the instructions you posted edi is just an address holder.
ST(0) is copied into the address held by EDI, it is not surprising that changing EDI would crash the game (it could also simply freeze a value).

Tell us what you want to do, most likely :
mov edi, xx
will crash the game however
mov [edi],xx
xx being a chosen value that supposedly work for whatever data type you are working with (most likely floats), should not crash the game
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Cake-san
Grandmaster Cheater
Reputation: 8

Joined: 18 Dec 2014
Posts: 541
Location: Semenanjung
PostPosted: Tue Mar 29, 2016 6:37 am    Post subject: Reply with quote
Gamemaker game ?
That instruction is a shared code which means it accessed many address.
You can either make a script that distinguished the address by cmp-ing the values in the stack or by going a little deeper to find out more. Wink
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Zanzer
I post too much
Reputation: 126

Joined: 09 Jun 2013
Posts: 3278
PostPosted: Tue Mar 29, 2016 5:39 pm    Post subject: Reply with quote
Code:
newmem:
  dq (double)9999
code:
  fstp qword ptr [edi]
  fld qword ptr [newmem]
  fstp qword ptr [edi]
  // the rest of the original code
INJECT:
  jmp code
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