[C++/ASM] Help in DEcompiling this code

Hi all im decompoling a File, i hve quite of success while doing this, until here i get an strange type of code ( The file was compiled on Visual C++ 6.0 Debug Type)

Code:

004E59CF |. 8B45 08 MOV EAX,[ARG.type] 004E59D2 |. 99 CDQ 004E59D3 |. 83E2 0F AND EDX,0F 004E59D6 |. 03C2 ADD EAX,EDX 004E59D8 |. C1F8 04 SAR EAX,4 004E59DB |. C1E0 05 SHL EAX,5 004E59DE |. 8B55 08 MOV EDX,[ARG.type] 004E59E1 |. 81E2 0F000080 AND EDX,8000000F 004E59E7 |. 79 05 JNS SHORT GameServ.004E59EE 004E59E9 |. 4A DEC EDX 004E59EA |. 83CA F0 OR EDX,FFFFFFF0 004E59ED |. 42 INC EDX 004E59EE |> 03C2 ADD EAX,EDX 004E59F0 |. 8945 F8 MOV [LOCAL._type],EAX

so i wrote in c++ this

Code:

int _type; // type is an int _type=((type/16*32))+UNKMACRO(type)

well the thing is that i don't know how to emulate the UNKMACRO that produce this code

Code:

004E59DE |. 8B55 08 MOV EDX,[ARG.type] 004E59E1 |. 81E2 0F000080 AND EDX,8000000F 004E59E7 |. 79 05 JNS SHORT GameServ.004E59EE 004E59E9 |. 4A DEC EDX 004E59EA |. 83CA F0 OR EDX,FFFFFFF0 004E59ED |. 42 INC EDX

This part do this

save ARG.type on EDX register
limit the EDX with 8000000F
if it is signed it will decrease the EDX, will OR it with 0xFFFFFFF0 and will increase it

so the MAcro should be

#define MACROLIMIT ( number, limit) ( .. code here )

but the problem is that i don't know any Macro that can emulate this, or any instruction that can handle the sign Flag in Debug, i would very gratefull if someone could help me in finding this strange macro

Re: [C++/ASM/Reverse] Help in DEcompiling this code

I try but I just don't understand what it is you want to do.

Re: [C++/ASM/Reverse] Help in DEcompiling this code

Well im a noob but i think i got what he's trying.

Is that the asembly code u extracted from a serial/code generator algorthm and you are trying to reverse to make a keygen?

if it is i have no freaking idea of cracking but XD at least i recogniced the assembly code ^_^

Re: [C++/ASM/Reverse] Help in DEcompiling this code

Quote:

Originally Posted by Negata

I try but I just don't understand what it is you want to do.

i need to reverse this code to c++

Code:

004E59CF |. 8B45 08 MOV EAX,[ARG.type] 004E59D2 |. 99 CDQ 004E59D3 |. 83E2 0F AND EDX,0F 004E59D6 |. 03C2 ADD EAX,EDX 004E59D8 |. C1F8 04 SAR EAX,4 004E59DB |. C1E0 05 SHL EAX,5 004E59DE |. 8B55 08 MOV EDX,[ARG.type] 004E59E1 |. 81E2 0F000080 AND EDX,8000000F 004E59E7 |. 79 05 JNS SHORT GameServ.004E59EE 004E59E9 |. 4A DEC EDX 004E59EA |. 83CA F0 OR EDX,FFFFFFF0 004E59ED |. 42 INC EDX 004E59EE |> 03C2 ADD EAX,EDX 004E59F0 |. 8945 F8 MOV [LOCAL._type],EAX

but i only got until the JNS jump, aftert that i can't get a JNS produced by the Visual c++ 6.0

Re: [C++/ASM/Reverse] Help in DEcompiling this code

Signed double-precision qord op of some sort.

Re: [C++/ASM/Reverse] Help in DEcompiling this code

Quote:

Originally Posted by username1

Signed double-precision qord op of some sort.

do you know any macro or function that can emulate that?

sage

Umm... just do arithmetic with long ints? -.-"

Re: sage

Quote:

Originally Posted by username1

Umm... just do arithmetic with long ints? -.-"

Yes seem to be just with ints , it is repeated in other part of the prgram

Code:

004EC480 |. 8B45 0C MOV EAX,[ARG.type] 004EC488 |. 25 FF000080 AND EAX,800000FF 004EC48D |. 79 07 JNS SHORT GameServ.004EC496 004EC48F |. 48 DEC EAX 004EC490 |. 0D 00FFFFFF OR EAX,FFFFFF00 004EC495 |. 40 INC EAX 004EC496 |> 8B4D 08 MOV [ARG.buf], EAX

Code:

004EC2D0 |. 8B45 12 MOV EAX,[ARG.item] 004EC2D8 |. 25 FF000080 AND EAX,8000000F 004EC2DD |. 79 07 JNS SHORT GameServ.004EC2E9 004EC2DF |. 48 DEC EAX 004EC2E0 |. 0D 00FFFFFF OR EAX,FFFFFFF0 004EC2E5 |. 40 INC EAX 004EC2E9 |> 034D FC MOV ECX,[LOCAL.n] // n is a pointer int * n; 004EC2EC |. 8801 MOV DWORD PTR DS:[ECX],EAX