Cheat Engine

Hatschi · Posted: Fri May 31, 2013 5:06 am Post subject: [Auto Assembler] Compare 8 Byte

Hi,

what is the command to compare an address with a 8 byte value?
4 Byte would be:

cmp dword ptr

And 8 byte?

Fresco · Posted: Fri May 31, 2013 5:31 am Post subject:

qword ptr
anyways that is if you have a x64 processor, if not use xmm or fpu

mgr.inz.Player · Posted: Fri May 31, 2013 8:55 am Post subject:

8 byte integer value ?

Like this:

Hatschi · Posted: Sun Jun 02, 2013 6:08 am Post subject:

Sounds great, by wouldn't it be enough to use fild qword ptr + a jump only? Or is it necessary to work with registers at this point?

mgr.inz.Player · Posted: Sun Jun 02, 2013 3:39 pm Post subject:

fcom[p[p]] do not change CPU flags (EFLAGS). So you need transfer STATUS WORD from FPU to CPU flag - fnstsw ax ; sahf

Yes there are other ways - SSE2

Hatschi · Posted: Sat Jun 29, 2013 10:19 am Post subject:

Sorry for bumping but I've got a question. How to compare a 64bit register with a 64bit (8 byte) value?

I've tried to write the 8 byte value in a codecave and then do something like:

fild qword ptr [00400300] <-- stored 8 byte value
fild qword ptr [R8]
fcompp
fnstsw ax
sahf
jne originalcode

Doesn't work, it seems like CE converts the 8 byte value into 4 byte.

Dark Byte · Posted: Sat Jun 29, 2013 11:04 am Post subject:

if it's an 8 byte and not a double, then do this:

Hatschi · Posted: Sat Jun 29, 2013 2:45 pm Post subject:

Same way as dealing with 32 bit addresses / 4 byte values except storing it, pretty easy haven't thought about this one thanks.

By the way, is it correct that the codecave scanner of CE doesn't support scanning in 64bit ranges? I may be wrong on this one too.

Dark Byte · Posted: Sat Jun 29, 2013 3:17 pm Post subject:

I even completly forgot ce had that thing(it's pretty much useless), so yeah, it won't scan 64-bit memory ranges