Wing Commander 3 BUN

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BUN

• Format Type : Archive
• Endian Order : Big Endian

BUN files are found on the 3DO version of Wing Commander III (in contrast to the PC version which uses TRE files).

Format Specifications

A BUN resource begins as follows:

 bytes 0-3    'FORM'
 bytes 4-7    total length of resource file, minus this 8-byte preamble
 bytes 8-11   'BUND'

Next, the file is comprised of a series of chunks with the following structure:

 bytes 0-3    chunk tag
 bytes 4-7    chunk length, not including 8-byte preamble
 bytes 8..    chunk payload

There are 2 known tags: 'DIR_' and 'FILE'. The 'DIR_' chunk contains a 12-byte record for each 'FILE' chunk in the resource:

 bytes 0-3    this appears to be a checksum/hash of the file; algorithm unknown
 bytes 4-7    absolute offset of 'FILE' chunk payload (not beginning of 'FILE' chunk itself)
 bytes 8-11   length of 'FILE' chunk payload (again, not length of entire 'FILE' chunk)

The remainder of the file is comprised of 'FILE' chunks. If a BUN resource contains 11 files, there will be 12 records in the 'DIR_' chunk and 12 corresponding 'FILE' chunks. Why the extra record? The first 'FILE' chunk contains filename information. The payload of this file chunk contains free-form strings separated by line-feed (ASCII 0xA) characters. The format of this payload appears to be:

compression_type = 0<lf><resource file name><lf><first file path and name><lf><second file path and name><lf> ... <lf><final file path and name>

Note that a directory path often precedes the filename. The rest of the 'FILE' chunks in the file simply have their represented raw file as the chunk payload.

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