Root cause: the original UC2 Pro expects csize=0 in the cdir COMPRESS
record (it ignores the field entirely). UC2 v3 was writing the actual
compressed size, which confused the original's archive reader.
Additional changes:
- Use default Huffman tree for all blocks (ensures tree encoding compat)
- Write method=compression_level in cdir COMPRESS (was hardcoded to 1)
- Add tests/scripts/bitdump.py for bit-level bitstream analysis
Single-file UC2 v3 archives are now fully readable by the original UC2
Pro (listing and extraction verified in DOSBox-X). Multi-file archives
still hang — the cdir bitstream decodes correctly in our Python analyzer
but fails in the original's ASM decompressor kernel. Investigation
continues; the bitdump.py tool enables targeted comparison.
Recursive directory scanning with parent/child ID tracking, directory
entries in the central directory (OSMETA + DIRMETA + EXTMETA long name
tags), and a CLI round-trip test verifying nested directory hierarchies.
Content-fingerprint grouping via FNV-1a hash of file headers: files
sharing identical first 4096 bytes are assigned a custom master block
built from the largest file in the group. Masters are compressed with
SuperMaster and written as MASMETA records in the central directory.
Files below 1 KB or without a group continue using the SuperMaster.
Includes CLI integration test and documentation updates (format spec,
usage, roadmap).
Restructure compat layer: #include_next headers moved to posix/ for
MinGW, new standalone headers in msvc/ for MSVC (unistd.h, utime.h,
getopt.h). Add getopt() implementation, chmod/unlink/chdir compat
functions, MSVC CRT initializer for UTF-8 console, _pgmptr fix.
Add a DJGPP CMake toolchain file and DOS compatibility layer (err.h,
fnmatch, getprogname/setprogname) so UC2 builds as a native DOS
executable via cross-compilation from Linux. The toolchain works
around a baked-in /usr/include in the DJGPP GCC binary by using -I
instead of -isystem to ensure DJGPP headers take precedence.
Add GitHub Actions CI workflow that builds and smoke-tests on both
ubuntu-latest and macos-latest.
Decompression MVP based on Jan Bobrowski's portable unuc2/libunuc2.
CMake build system targeting Linux (GCC/Clang) with MSVC fallback.
Includes original UC2 source by Nico de Vries and unuc2-0.6 for reference.
Eremey Valetov