Program to handle archives from the 1995 title Big Red Racing.
The latest binaries for Windows, Debian and macOS are available at GitHub Releases.
To unpack a given archive DIRT1.ENV to folder DIRT1, execute the following.
red-archive -u DIRT1.ENV DIRT1To pack a given folder DIRT1 into archive DIRT1.ENV, execute the following.
red-archive -p DIRT1 DIRT1.ENVCompilation requires a C compiler and CMake.
To generate the build files, execute the following from the root project folder.
cmake . -B buildTo build the project, execute the following from the root project folder.
cmake --build buildYou can find the output binaries in the bin folder.
The Big Red Racing archive format and compression methods are unidentified and therefore undocumented other than what's written here.
The archive format has no header like is typical with other formats, and does not support directories. Each file is stored consecutively in the archive, with a structure as shown below.
| Offset | Bytes | Description |
|---|---|---|
| 0 | n | File name (null-terminated) |
| n | 4 | Compressed size (m) |
| n + 4 | 4 | Uncompressed size |
| n + 8 | 1 | Compression type |
| n + 9 | m | File data |
Type 0 indicates an uncompressed file.
Type 1 is a very simple compression method suitable for compressing small files.
A flag byte n indicates whether the next n bytes are copied as-is (where n < 128), or the following byte is repeated m times (where m = n - 125).
Type 2 is a more complicated compression method capable of better compression in large files.
It has a compression type value ranging from 2 to 6. The size in bits for the run length and offset are calculated from the compression type value.
The bits in a flag byte represent whether the following 8 chunks are compressed or uncompressed.
If a chunk is uncompressed, it is a single uncompressed byte and is copied to the circular and output buffer.
If a chunk is compressed, it consists of two bytes which, on a bit-level as dictated by the compression type value, represent the offset and run length in the circular buffer. These bytes are then copied to the circular and output buffer.