162cf462b6
- Mark test corpus/archives as binary in .gitattributes to prevent line ending conversion on CI (fixes extract test size mismatch) - Fix alignment-unsafe struct cast in uc2_dict.c serialize/deserialize (use memcpy-based byte access instead; fixes SEGFAULT on CI) - Fix formatting issues in docs
119 lines
4.1 KiB
Markdown
119 lines
4.1 KiB
Markdown
# UC2 v3.0.0 -- UltraCompressor II
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A cross-platform revival of UltraCompressor II, the DOS-era archiver by
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Nico de Vries (1992--1996). UC2 was notable for its advanced deduplication
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("master blocks"), file versioning, and competitive compression ratios on
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the hardware of its day.
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UC2 v3 brings it back as a modern, portable C99 tool with full
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backward compatibility -- archives created by UC2 v3 can be extracted
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by the original 1992 UC2 Pro, and vice versa.
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## Features
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- **Full compression and decompression** -- LZ77+Huffman (levels 2--5),
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rANS entropy coding (levels 6--9), LZ4 ultra-fast mode
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- **Backward compatible** with the original UC2 Pro (verified via
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automated DOSBox-X cross-tool round-trip testing)
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- **Content-defined chunking** (CDC) with Gear rolling hash for
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position-independent deduplication
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- **Merkle DAG** content addressing with 64-bit hashes
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- **Cross-archive dedup** via shared block store
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- **Near-duplicate detection** via SimHash
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- **Delta compression** for binary patching
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- **Content-aware preprocessing** -- BCJ (x86), BWT (text), delta filter
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- **BLAKE3** cryptographic hashing for archive integrity
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- **Benchmark mode** -- test all methods on input data
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- **Personality** -- warm, confident status messages (`-q` for scripting)
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- Directory archival with nested hierarchies
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- Cross-platform: Linux, macOS, Windows (MSVC), DOS (DJGPP)
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## Building
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Requires CMake >= 3.16 and a C99 compiler (GCC, Clang, or MSVC).
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```sh
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cmake -B build
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cmake --build build
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ctest --test-dir build # 16 unit tests
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```
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## Usage
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```sh
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uc2 -w archive.uc2 files... # Create archive
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uc2 archive.uc2 # Extract all files
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uc2 -l archive.uc2 # List contents
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uc2 -t archive.uc2 # Test integrity
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uc2 -d /tmp/out archive.uc2 # Extract to directory
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uc2 -w -L 8 archive.uc2 files... # Create with rANS Tight
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uc2 -B files... # Benchmark all methods
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```
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### Compression Levels
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| Level | Method | Description |
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|-------|--------|-------------|
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| 2 | Huffman | Fast |
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| 3 | Huffman | Normal |
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| 4 | Huffman | Tight (default) |
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| 5 | Huffman | Ultra |
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| 6 | rANS | Fast |
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| 7 | rANS | Normal |
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| 8 | rANS | Tight |
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| 9 | rANS | Ultra |
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Levels 2--5 produce archives readable by the original 1992 UC2 Pro.
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Levels 6--9 use rANS entropy coding (UC2 v3 only, better compression).
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### Options
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| Flag | Description |
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|------|-------------|
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| `-w` | Create archive |
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| `-l` | List archive contents |
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| `-t` | Test archive integrity |
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| `-L n` | Compression level (2--9) |
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| `-B` | Benchmark all methods on input files |
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| `-d path` | Extract to specified directory |
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| `-f` | Overwrite existing files |
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| `-p` | Extract to stdout |
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| `-q` | Quiet (suppress status messages) |
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| `-a` | Include all file versions |
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| `-D` | Skip directory metadata; `-DD` also skips file metadata |
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| `-T` | Tab-separated output |
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## Project Structure
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```
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UC2/
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lib/ libuc2 compression/decompression library
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include/uc2/ public headers (libuc2, uc2_cdc, uc2_merkle, uc2_rans, ...)
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src/ library implementation
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cli/ uc2 command-line tool
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tests/ unit tests and test corpus
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original/ preserved original UC2 Pro sources (reference only)
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docs/ Sphinx documentation
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```
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## Credits
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- **Nico de Vries** -- Original UltraCompressor II (1992--1996)
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- **Danny Bezemer** -- Facilitated source code release (2015)
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- **Jan Bobrowski** -- Clean-room portable decompressor (unuc2/libunuc2, 2020--2021)
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- **Eremey Valetov** -- UC2 v3 revival, compression engine, deduplication, and ongoing development
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See [CREDITS.md](CREDITS.md) for full attribution.
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## History
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- **v1.0--v2.3** (1992--1996) Original DOS releases by Nico de Vries
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- **2015** Source code released under LGPL-3.0 by Danny Bezemer
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- **2020--2021** Jan Bobrowski writes unuc2/libunuc2 (portable decompressor)
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- **2026** UC2 v3.0.0: cross-platform revival with full compression engine,
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backward compatibility, and modern deduplication
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## License
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GPL-3.0. See [LICENSE](LICENSE) and [CREDITS.md](CREDITS.md).
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