Hacking Steins;Gate Hiyoku Renri no Darling for the PSP

[monokuma77]

Hi,
I am having a problem discovering some assets of the game Steins;Gate Hiyoku renri no Darling for the PSP and I would like to request some help.

I have found almost everything from the game (visual novel) like text, CGs, background images, character sprites, videos, audio (wav, hca etc) BUT I cannot find the images used in the menu and settings.

The game packs its resources in two big files data0.cpk and data1.cpk which can be easily unpacked. The files they contain can also be easily unpacked and I get the following file tree:

DATA0.CPK
--BGL00.CPK (Large background images TIM2 format)
--BGS00.CPK (Small background images TIM2 format)
--CHL00.CPK (Large character images TIM2 format)
--CHS00.CPK (Small character images TIM2 format)
--CONFIG.CPK (6 very small files!)
--DATA0.CLS (list of the files in this archive)
--FONTS.CPK (font files)
--ICON.CPK (2 png images)
--OBJSY.cpk (UNKNOWN)
--SCENE00.cpk (game text)
--SE00.CPK (sound effects audio files)
--VO00.CPK (voices audio files)
--VO01.CPK (voices audio files)

DATA1.CPK
--DATA1.CLS (list of the files in this archive)
--SE01.CPK (wav audio files, sound effects)
--SE02.CPK (wav audio files, sound effects and pmf video files)

I've identified almost everything, so where can those images be?
For example, in the main menu->System->Manual there is an image explaining the controls. This image is actually composed of three different images one on top of the other and with the use of alpha channel it displays like this. I deduced this with the help of the PPSSPP emulator's debug GE mode, but I can't understand the memory addresses in order to find where those textures come from.

Obviously I checked the uncompressed elf of the eboot.bin but no luck.

Any help would be really really appreciated!
Thank you.

 

[thexyz]

what did you use to extract cpk?

 

[monokuma77]

what did you use to extract cpk?

I used a command line tool named cpk_unpack.exe to extract the files. And a cpkmakec.exe to rebuild the cpk.

 

[thexyz]

Can't you just attach the .exe? I mean, if you're looking for help it'd make more sense to provide all information you have so that other people don't spend their time researching what's already known.

 

[monokuma77]

Can't you just attach the .exe? I mean, if you're looking for help it'd make more sense to provide all information you have so that other people don't spend their time researching what's already known.

Of course. But I don't have the code for them. Just the executables.
I've included both.

 

[thexyz]

Looks like textures are stored in OBJSY.CPK inside 03.bin or 08.bin for the manual, I'm not sure. sub_B4164 does the decompression, $a0 is output buffer and $a1 is input. Dunno what compression they use since I haven't worked with that stuff, but it's probably some variation of LZ/LZSS (I mean, it's always LZ).

 

[Riku]

just what thexyz said..

http://i.imgur.com/Z2P7MaF.png

 

[monokuma77]

Thank you very much.

Riku Since you've actually managed to get a picture out of OBJSY.CPK (was it in the 08.bin?) can you please tell me exactly what you did and what utilities you used?

Is there a specific utility that can use this LZ/LZSS algorithm to decompress these files?