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TTEMMA, posted Mon Sep 10, 2018 8:01 am (38239)

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Hi.
At the moment I'm trying to disassemble the compression into Resident Evil 4 on the Gamecube.
There is a complex and not understandable compression. At the beginning of the decompression, the game generates a table.
It stores items from 0 to 0x500, but the number of each number is divided in a strange way. For example, if value < 0x300 (for example, 0x012C) then the table will record 26(0x1A) items with a value of 0x012C. If value > 0x300 (for example, 0x0400) the table will record 25(0x19) items with a value of 0x0400.

Decompression is even stranger, each byte is decompressed by 4 bytes from the compressed file (4 bytes are divided into a flag that is built dynamically and is not stored in a compressed file).

I ask for help with mastering the compression algorithm, perhaps, in my description, you saw some familiar compression algorithm for yourself.

Thank You

aluigi, posted Thu Sep 13, 2018 7:17 pm (38295)

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Can you provide some sample files of the game that use this compression?

TTEMMA, posted Fri Sep 14, 2018 6:28 am (38326)

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Compressed data start from 0x20, compressed size and decompressed contain in first 0x20 bytes

https://drive.google.com/open?id=1Cn_pj ... 61ZQjhOP19

aluigi, posted Fri Sep 14, 2018 12:20 pm (38343)

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No idea about what would be the algorithm and moreover about what decompressed data we should expect.

TTEMMA, posted Fri Sep 14, 2018 9:53 pm (38379)

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Okay, i upload 2 files:
r100.bin - compressed
r100decoded.bin - decompressed

Maybe this help you

https://drive.google.com/open?id=11HmKD ... VOsYGPfEwR