Files

T

osobhandClaude Opus 5.5 159e588550 filters: Fletcher-32 as libhdf5 computes it

Our checksum reduced its sums with `% 65535`; libhdf5's
H5_checksum_fletcher32 folds them with `(s & 0xffff) + (s >> 16)`, which
leaves 0xffff where the modulo leaves 0. On about one chunk in 32768
libhdf5 refused the chunks we wrote and we refused the chunks it wrote.
Every release since v2.1.0 is affected.

clawhdf5_format::checksum::fletcher32 is a port of H5_checksum_fletcher32
and the filter's only implementation. Verification also accepts the
byte-swapped form libhdf5 accepts (1.6.2 and earlier) and the `% 65535`
form earlier releases wrote, so their files stay readable.

The new interop test compares the checksum with libhdf5's own function
(ctypes) on every 1- and 2-byte input and 40 000 random and fold-heavy
inputs, and moves fold-case chunks between h5py and FileBuilder/FileEditor
in both directions; with the old filters.rs the three file tests fail.

Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>

2026-09-26 18:50:23 -05:00

src

filters: Fletcher-32 as libhdf5 computes it

2026-09-26 18:50:23 -05:00

Cargo.toml

build: declare Rust 1.92 as the MSRV and check it in CI

2026-09-23 11:05:26 -05:00

README.md

docs: fix stale package names, counts, and CLI subcommands

2026-06-03 11:17:04 +00:00

README.md

clawhdf5-accel

SIMD-accelerated operations for clawhdf5.

Features

AVX2 and NEON SIMD acceleration
AVX-512 support (avx512 feature)
Float16 conversion (float16 feature)
CRC32 checksum acceleration

Usage

use clawhdf5_accel::checksum::crc32_simd;

let crc = crc32_simd(&data);

License

MIT