Compression and Decompression

Game Boys don’t have a lot of RAM (128KB tops); in order for LSDJ to deal with such a limited amount of space, it has to pack files in pretty tight. To do this, it uses an algorithm referred to on the LSDJ wiki as the “file pack algorithm”.

pylsdj includes functions that will compress and decompress lists of bytes using the file pack algorithm.

Typically you don’t need to do this: .sav files compress themselves on save and decompress themselves on load automatically. If your application needs to do something fancy with LSDJ’s filesystem, however, you can use the compression and decompression functions by themselves.

Usage Examples

from pylsdj import filepack

# Here's a list of bytes
bytes = [0x12, 0x12, 0x12, 0x15, 0x15, 0x10]

# We can compress those bytes
compressed = filepack.compress(bytes)

# ... and then decompress them again
decompressed = filepack.decompress(compressed)

API Documentation

pylsdj.filepack.compress(raw_data)

Compress raw bytes with the filepack algorithm.

Parameters:raw_data – an array of raw data bytes to compress Return type:a list of compressed bytes

pylsdj.filepack.decompress(compressed_data)

Decompress data that has been compressed by the filepack algorithm.

Parameters:compressed_data – an array of compressed data bytes to decompress Return type:an array of decompressed bytes