Implements decompression for the scale-offset filter (id 6), integer mode
(H5Z_SO_INT) — previously returned UnsupportedFilter(6). The on-disk format was
reverse-engineered against HDF5 2.0 / h5py and verified across signed/unsigned
element sizes, negative minima, multi-chunk datasets and fill-value handling:
minbits (u32 LE) | 0x08 | minval (8 bytes LE) | 8 reserved bytes |
MSB-first packed codes (nelmts * minbits bits)
Each code is `value - minval`; the all-ones code is reserved for the (defined)
fill value. The floating-point variants (D-scale/E-scale) use a different
algorithm and remain reported as unsupported.
Validated end-to-end (a 200-element chunked scale-offset dataset, plus negative
and unsigned datasets, now decode to the exact h5py values). Adds h5py-free unit
tests using real captured compressed chunks.
Co-Authored-By: Claude Opus 4.8 (1M context) <[email protected]>
Follow-up to the v5 compound fix, found by an interop sweep over diverse
h5py/HDF5 2.0 (libver=latest) datasets:
- Array datatype (class 10) version 5 was rejected. v3/v4/v5 share the same
array encoding, so the parser now accepts 3-5.
- Data Layout message version 5 was rejected, which broke EVERY chunked/
compressed dataset written by modern HDF5. v5 reuses the v4 message
structure, so it now routes through parse_v4.
Validated end-to-end: a gzip-compressed, Fixed-Array-indexed v5 chunked dataset
now decodes to the correct values. Adds h5py-free regression tests using the
real v5 array-datatype and chunked-layout bytes, and updates the layout
invalid-version test to use v6.
Co-Authored-By: Claude Opus 4.8 (1M context) <[email protected]>
clawhdf5 rejected datatype message version 5 for the compound class with
"invalid datatype version 5 for class 6", so it could not read compound
datasets written by modern HDF5 / h5py with libver=latest. v5 reuses the same
compact member encoding as v3/v4 (name, variable-width offset, member type), so
the parser now accepts versions 3-5 for compound.
Found by running the previously-ignored h5py interop tests against h5py 3.16 /
HDF5 2.0. Adds an h5py-free regression test using the real v5 datatype bytes.
Co-Authored-By: Claude Opus 4.8 (1M context) <[email protected]>
build_chunked_data_at_ext now compresses all chunks via compress_all_chunks
(previously dead code) before laying them out, so compression runs across
rayon threads under the `parallel` feature when there are >4 filtered chunks.
Layout is unchanged — compression preserves chunk order, so on-disk bytes are
identical to the sequential path. The agent crate enables `parallel`, so this
speeds up compressed embedding writes.
Removes the #[allow(dead_code)] on compress_all_chunks and gates
PARALLEL_COMPRESS_THRESHOLD behind the `parallel` feature.
Co-Authored-By: Claude Opus 4.8 (1M context) <[email protected]>
