Cheat Engine

CosmoCortney · Posted: Wed Apr 01, 2015 5:47 am Post subject: Cheat Engine bug found

Hi,
I've been using Cheat Engine for various kinds of game hacking including game corruptions.
As it comes to corrupting Wii-, GameCube and N64 games as they are running on an emulator I have noticed an annoying bug.
Any comparison with the value of 0x3F800000 gives me 0 results (the only values being shown belong to the emulator but not to the game).
If I open a GameCube or Wii RAM dump with cheat engine I will be left with 0 results, too (even there are thousands of addresses storing a value of 0x3F800000). But comparisons for other floats like, 0x40000000 or 0x3F000000 work fine.

Dark Byte · Posted: Wed Apr 01, 2015 5:57 am Post subject:

for emulators enable mem_mapped memory regions in the settings->scan settings

CosmoCortney · Posted: Wed Apr 01, 2015 6:12 am Post subject:

no changes

Dark Byte · Posted: Wed Apr 01, 2015 6:15 am Post subject:

are those big endian systems?
If so, instead of scanning for 0x3F800000 scan for 0x0000803f

or try this:
http://forum.cheatengine.org/viewtopic.php?p=5305367#5305367

CosmoCortney · Posted: Wed Apr 01, 2015 6:41 am Post subject:

the first method surprisingly works. thank you!
but why do the values look normal in the mem viewer?

Dark Byte · Posted: Wed Apr 01, 2015 6:59 am Post subject:

big endian stores the bytes in the opposite order as little endian

in little endian (e.g intel x86) 0x3f800000 is stored as 00 00 80 3f
in big endian (e.g n64) 0x3f800000 is stored as 3f 80 00 00

when you interpret a big endian 4 byte value as a little endian 4 byte value, the cpu will read 3f 80 00 00 as 0000803f