NOP 2 bytes

06 Fev 2019, 14:39

I just found a old post by Silent & just interested to know what he is actually means.
Imagem

06 Fev 2019, 20:35

WRITE_MEMORY 0x58DD1B 2 0x90 TRUE

0x90 = NOP

07 Fev 2019, 11:56

Junior_Djjr escreveu: ↑
06 Fev 2019, 20:35
WRITE_MEMORY 0x58DD1B 2 0x90 TRUE

0x90 = NOP

Thanks but it seems that this only works when i do NOP 1 byte!

07 Fev 2019, 23:25

Junior_Djjr escreveu: ↑
06 Fev 2019, 20:35
WRITE_MEMORY 0x58DD1B 2 0x90 TRUE

0x90 = NOP

Try using 0x9090 as value.

I think the WRITE_MEMORY only works as memory fill when size is not 1, 2 or 4 bytes.

07 Fev 2019, 23:44

Fabio escreveu: ↑
07 Fev 2019, 23:25

Junior_Djjr escreveu: ↑
06 Fev 2019, 20:35
WRITE_MEMORY 0x58DD1B 2 0x90 TRUE

0x90 = NOP
Try using 0x9090 as value.

I think the WRITE_MEMORY only works as fill when size is not 1, 2 or 4 bytes.

Yes.

Código: Selecionar tudo

// copies @proto object to the object given by memory address @addr
template<typename T> void MemoryWrite(memory_pointer addr, const T& proto, bool force_vp = false, size_t n = 1)
{
    DWORD oldProtect;
    if(force_vp) VirtualProtect(addr, sizeof(T) * n, PAGE_EXECUTE_READWRITE, &oldProtect);
    if(n != 1) MemFill(addr, proto, n);
    else MemWrite(addr, proto);
    //if(force_vp) VirtualProtect(addr, sizeof(T) * n, oldProtect, &oldProtect);
}

07 Fev 2019, 23:57

Israel escreveu: ↑
07 Fev 2019, 23:44
Fabio escreveu: ↑
07 Fev 2019, 23:25

Junior_Djjr escreveu: ↑
06 Fev 2019, 20:35
WRITE_MEMORY 0x58DD1B 2 0x90 TRUE

0x90 = NOP
Try using 0x9090 as value.

I think the WRITE_MEMORY only works as fill when size is not 1, 2 or 4 bytes.
Yes.
Código: Selecionar tudo
// copies @proto object to the object given by memory address @addr
template<typename T> void MemoryWrite(memory_pointer addr, const T& proto, bool force_vp = false, size_t n = 1)
{
    DWORD oldProtect;
    if(force_vp) VirtualProtect(addr, sizeof(T) * n, PAGE_EXECUTE_READWRITE, &oldProtect);
    if(n != 1) MemFill(addr, proto, n);
    else MemWrite(addr, proto);
    //if(force_vp) VirtualProtect(addr, sizeof(T) * n, oldProtect, &oldProtect);
}

https://github.com/cleolibrary/CLEO4/bl ... m.cpp#L861

09 Mar 2020, 07:09

I've another question and since it's related to the actual topic am asking it here,

How do I calculate the size of the address that I want to NOP? For example, I wanted to freely move the mouse cursor in-game.

For the cursor visibility, I passed true to this function,

Código: Selecionar tudo

int __cdecl RsMouseSetVisibility(BOOL visibility) // 0x619490
{
  return psMouseSetVisibility(visibility);
}

It worked as expected. Then I needed to NOP the function which set the cursor position. I found this is probably the one,

Código: Selecionar tudo

int __cdecl psMouseSetPos(RwV2d *pos) // 0x7453F0
{
    // code
}

So am I doing this correctly? How can I calculate the size for it?
Anyway thanks again.

09 Mar 2020, 12:32

Grinch_ escreveu: ↑
09 Mar 2020, 07:09
I've another question and since it's related to the actual topic am asking it here,

How do I calculate the size of the address that I want to NOP? For example, I wanted to freely move the mouse cursor in-game.

For the cursor visibility, I passed true to this function,
Código: Selecionar tudo
int __cdecl RsMouseSetVisibility(BOOL visibility) // 0x619490
{
  return psMouseSetVisibility(visibility);
}
It worked as expected. Then I needed to NOP the function which set the cursor position. I found this is probably the one,
Código: Selecionar tudo
int __cdecl psMouseSetPos(RwV2d *pos) // 0x7453F0
{
    // code
}
So am I doing this correctly? How can I calculate the size for it?
Anyway thanks again.

You need to use a disassembler to look the assembly instructions. The disassembler shows the instruction size. Sometimes you will need to NOP more than one instruction.

f15-tutoriais/t1215-engenharia-reversa- ... tes#p10103

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