bzip2 demo

Build the upstream bzip2 1.0.8 library through badc and run a buffer-to-buffer compress + decompress round-trip at blockSize 1 (smallest) and blockSize 9 (largest).

bzip2 is integer + bit-twiddle heavy: Burrows-Wheeler transform, move-to-front, run-length encoding, and Huffman coding through a 128-bit bitstream packer. Different shape from miniz’s deflate – no LZ77 window, so a regression here usually pinpoints something miniz didn’t notice.

The library source isn’t committed: setup.py fetches the 1.0.8 release tarball from sourceware.org and drops the seven .c files + two headers into this directory.

Files

File	Tracked?	Purpose
`setup.py`	yes	Fetch + extract the release tarball. Idempotent.
`smoke.py`	yes	Build with badc + run the buffer-to-buffer round-trip.
`smoke_main.c`	yes	The hand-written test driver. Pulls only public bzlib APIs.
`blocksort.c`	no	BWT + main sort. Produced by `setup.py`.
`huffman.c`	no	Huffman coding pass. Same.
`crctable.c`	no	Static CRC32 table. Same.
`randtable.c`	no	Static randomisation table. Same.
`compress.c`	no	Compression driver. Same.
`decompress.c`	no	Decompression driver. Same.
`bzlib.c`	no	Public API surface. Same.
`bzlib.h`	no	Public API header. Same.
`bzlib_private.h`	no	Internal header. Same.
`.cache/`	no	Cached release tarball.

Workflow

python demos/bzip2/setup.py    # fetches into demos/bzip2/
python demos/bzip2/smoke.py    # builds + runs four scenarios at -O and noO

smoke.py returns 0 with smoke OK [no-O]: 4 scenarios green / smoke OK [-O]: 4 scenarios green when both -O and noO builds pass every scenario:

mixed (64 KiB) – text + binary sweep, modest ratio.
zeros (64 KiB) – low entropy; cmp_len must crush to < 2%.
random (64 KiB) – xorshift64 stream; cmp_len ~= src_len.
reference – decompress a hand-baked bzip2 stream (Python bz2.compress of a fixed plaintext, base64 in the driver) and verify byte-equality. Catches any decompress-side regression independent of the encoder path.

Anything else returns 1 with a diagnostic on stderr.

smoke.py honours BADC=path/to/badc.

Build defines

BZ_NO_STDIO – drops the FILE *-shape API (BZ2_bzReadOpen / BZ2_bzWriteOpen / bzdopen / etc.). We only use the buffer-to-buffer entry points (BZ2_bzBuffToBuffCompress / BZ2_bzBuffToBuffDecompress), which don’t touch stdio. Avoids a <sys/stat.h> clash with the c5 header set on Windows.

CI

Same five runners as the other demos: ubuntu-latest, ubuntu-24.04-arm, macos-latest, windows-latest, windows-11-arm.

Bumping bzip2

Update VERSION in setup.py to the new release.
Run python setup.py -v followed by python smoke.py.

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