Search found 25 matches

by Malvineous
Sat May 17, 2014 11:15 am
Forum: Compressed files and methods
Topic: The Lost Vikings (DOS) compression algorithm
Replies: 0
Views: 1707

The Lost Vikings (DOS) compression algorithm

Hi all, I'm hoping this is an easy one. Does anyone know what compression algorithm is used by The Lost Vikings? Here is a sample compressed file . After decompression it should be in XMI format. I don't have a decompressed version of it, but here is another file in XMI format which should be much t...
by Malvineous
Sun Dec 08, 2013 12:30 am
Forum: Compressed files and methods
Topic: SkyRoads compressed levels
Replies: 4
Views: 2658

Re: SkyRoads compressed levels

No worries, thanks again. I've put your code and an explanation in the SkyRoads compression article on the ModdingWiki. I've also found that the image files use the same compression algorithm, so I've been able to start reverse engineering some other files too.
by Malvineous
Sat Dec 07, 2013 4:23 am
Forum: Compressed files and methods
Topic: SkyRoads compressed levels
Replies: 4
Views: 2658

Re: SkyRoads compressed levels

Fantastic, many thanks! I had to adjust the code a little - where you have "count = 1 + getbits..." I had to change it to "2 +" and then it worked perfectly.

Thanks to this, hopefully it won't be too long now before SkyRoads levels can be edited in Camoto!
by Malvineous
Fri Nov 29, 2013 12:24 pm
Forum: Compressed files and methods
Topic: SkyRoads compressed levels
Replies: 4
Views: 2658

SkyRoads compressed levels

Hi all, I'm trying to reverse engineer the compression algorithm used by the DOS game SkyRoads to compress its levels. I've attached four example files, both compressed and decompressed. The decompressed versions were obtained from a DOSBox memory dump, so there are extra trailing 0x00 bytes. The fi...
by Malvineous
Sun Nov 17, 2013 12:40 pm
Forum: Compressed files and methods
Topic: Zone 66 compression format
Replies: 38
Views: 12458

Re: Zone 66 compression format

I've just posted a version of Camoto (version 20131117) that can kind of edit Zone 66 levels. You can open the level, change it, and save it, but for some reason the game locks up when it tries to load the modified level. I don't know why it does this, but there must be a problem with the compressio...
by Malvineous
Sat Oct 12, 2013 10:15 am
Forum: Game Archive
Topic: Request for Raptor - Call of the Shadows GLB-file
Replies: 3
Views: 1837

Re: Request for Raptor - Call of the Shadows GLB-file

Last post - I've successfully reverse engineered this file format. I am in the process of writing up an explanation for the full encryption algorithm and the file structures, which will appear shortly on the ModdingWiki page for the GLB format.
by Malvineous
Sat Oct 12, 2013 10:13 am
Forum: Compressed files and methods
Topic: [Solved] Raptor GLB - decryption help (XOR?)
Replies: 1
Views: 946

Re: Raptor GLB - decryption help (XOR?)

Just to save anyone the time on this, I have reverse engineered the algorithm used by the game and so this problem is now solved. As it turns out the game does not quite use XOR, which is why the values were appearing strangely. I am in the process of writing up an explanation for the full encryptio...
by Malvineous
Sat Oct 12, 2013 2:49 am
Forum: Compressed files and methods
Topic: [Solved] Raptor GLB - decryption help (XOR?)
Replies: 1
Views: 946

[Solved] Raptor GLB - decryption help (XOR?)

Hi all, I am struggling to decrypt the filenames in the Raptor GLB format. I have obtained the decrypted filenames from a memory dump, but I am stuck trying to figure out the decryption algorithm. Here is the mapping between the encrypted bytes and the decrypted data. Each character position has a s...
by Malvineous
Fri Oct 11, 2013 1:31 pm
Forum: Code Talk
Topic: Little Endian to Big Endian
Replies: 6
Views: 3566

Re: Little Endian to Big Endian

I have a C++ utility header that can also do this.

Code: Select all

#include "byteorder.hpp"
int val = be16toh(1234); // be16toh = big-endian 16-bit to host

std::fstream file("test.dat");
uint16_t value;
file >> u16be(value); // read 16-bit big-endian value from file stream
by Malvineous
Fri Oct 11, 2013 11:20 am
Forum: Game Archive
Topic: Request for Raptor - Call of the Shadows GLB-file
Replies: 3
Views: 1837

Re: Request for Raptor - Call of the Shadows GLB-file

I've just had a closer look at this format, and this is what I have discovered so far: Only the FAT (the list of filenames and offsets) is encrypted. This is the first 43008 bytes of the file, which is 768 file entries of 56 bytes each. I have only managed to partially decrypt so far. By taking each...
by Malvineous
Fri Oct 11, 2013 10:09 am
Forum: Game Archive
Topic: Request for Raptor - Call of the Shadows GLB-file
Replies: 3
Views: 1837

Re: Request for Raptor - Call of the Shadows GLB-file

Sorry about digging up such an old topic, but I was just going to post the same question anyway.

Does anyone know if any progress has been made in the last five years with this file format?
by Malvineous
Tue Nov 15, 2011 10:27 am
Forum: Compressed files and methods
Topic: Stargunner DLT compression
Replies: 3
Views: 1849

Re: Stargunner DLT compression

Thanks for investigating.

I've had an e-mail from someone who disassembled the algorithm and coverted it to C. If anyone is interested, I will be documenting it over the coming weeks on the Game Modding Wiki and of course implementing it in Camoto/libgamearchive.
by Malvineous
Sat Nov 12, 2011 1:09 am
Forum: Compressed files and methods
Topic: Stargunner DLT compression
Replies: 3
Views: 1849

Re: Stargunner DLT compression

Looking at this further, it seems there are actually two variants to the compression, but they all seem to be based around byte pair encoding . Focusing on one for the moment (the one in the files I posted above), it seems to be roughly in this structure (using data from title.mod as an example) 50 ...
by Malvineous
Thu Nov 10, 2011 1:09 pm
Forum: Compressed files and methods
Topic: Stargunner DLT compression
Replies: 3
Views: 1849

Stargunner DLT compression

Hi all, Following on from this post back in 2006 I had another look at the Stargunner compression format. It looks tantalisingly simple, but alas I'm struggling somewhat. I've uploaded a couple of files (compressed and decompressed versions) so if anyone is willing to take a quick look that would be...
by Malvineous
Sun Feb 06, 2011 3:09 am
Forum: Compressed files and methods
Topic: Zone 66 compression format
Replies: 38
Views: 12458

Re: Zone 66 compression format

Yeah everything's almost back to normal now, just a lot of cleanup going on. My local supermarket is still closed while they clean out the mud, but at least I didn't have to rip out and replace everything in my home (including the walls) like those people whose places went under... And yes, this is ...