[Req] .pac format for PSP (Magical Girl Lyrical Nanoha A's)

[szfzafa]

The game is called Magical Girl Lyrical Nanoha A's Portable: The Battle of Aces.


Here are some samples of .pac package, from ?:\PSP_GAME\USRDIR\
http://www.gamefront.com/files/20246953/pac_samples.rar

They contain .gim images/textures and .gmo 3d models. You can see filenames inside them.

Also, I found some bytes with certain meanings:
(click to enlarge)
But still cannot get the correct file context. Maybe it's using a LZS algorithm.

Anyone take a look into this format would be a great help.. thx~

[aluigi]

I don't know what compression it is or if it could be an lzss with different parameters (those I tested gave no good results) so the following is the script without decompression:

Code: Select all

# NO DECOMPRESSION
idstring "add"
goto 0x10
get FILES long
goto 0x20
for i = 0 < FILES
    get OFFSET long
    get SIZE long
    get DUMMY long
    get DUMMY long
    get NAME_OFF long
    get DUMMY long
    get DUMMY long
    get DUMMY long
    savepos TMP
    goto NAME_OFF
    get NAME string
    goto OFFSET
    getdstring SIGN 3
    if SIGN == "LZS"
        get DUMMY byte
        get DUMMY long
        get HEAD_SIZE long
        get DUMMY long
        get SIZE long
        get ZSIZE long
        math ZSIZE  -= HEAD_SIZE
        math OFFSET += HEAD_SIZE
        #clog NAME OFFSET ZSIZE SIZE
        log NAME OFFSET ZSIZE
    else
        log NAME OFFSET SIZE
    endif
    goto TMP
next i

so it's mainly for developers who want to find what is the algorithm

[szfzafa]

I don't know what compression it is or if it could be an lzss with different parameters (those I tested gave no good results) so the following is the script without decompression:
......
so it's mainly for developers who want to find what is the algorithm

Seems hopeless..
This game cannot be emulated yet; it's almost impossible to get assembly instructions. Then how can we know the algorithm? That's really hard..

Correctly I even dunno if this compression is in byte-level or bit-level..

Anyway, thx 4 your scripts!

[szfzafa]

...

problem solved.
take a look at this: viewtopic.php?p=53922#p53922

if u really care about the details, i'll translate the Chinese comments in the src into English. but i still misunderstand how unpac works..

[chrrox]

post the tool?

[szfzafa]

post the tool?

As i said in viewtopic.php?p=53907#p53907, leoheart, the translator, posted the tool in his fc2 blog (http://leoheart.blog43.fc2.com/?mode=edit&rno=2150) in a MF link.
don't forget to add "-z" parameter. usage: viewtopic.php?p=53926#p53926

btw, i saw u in gameresearch.5d6d, chrrox~

[kinlyki]

Can someone reupload the unpac tool? The mediafire link is dead