osobhandClaude Opus 5.5
735db117a7
The core crates (clawhdf5, -agent, -format, -io, -filters, -ann, -accel, -netcdf4, -cli) now build no C by default: deflate defaults to zlib-rs, a pure-Rust port of zlib-ng, and zlib-ng becomes the opt-in `fast-deflate`, which overrides zlib-rs wherever it is enabled. A default build no longer needs cmake or a C compiler. Measured on tank, both builds run alternately, three rounds, medians: zlib-rs is within 6% of zlib-ng on every HDF5 read and write (512x512 deflate-6 chunked write 1.458 vs 1.484 ms; 64 MB compressed read 64.4 vs 65.2 ms), and compressed output is byte-identical. Details in BENCHMARKS.md, "Deflate backend". Getting there took two fixes the first measurement exposed: - zlib-rs needs `std` to detect SIMD at runtime. flate2 enables it via its default `runtime_detection`, which `default-features = false` had switched off, leaving zlib-rs 3.5x slower on inflate. The `zlib-rs` features now enable it. - Both deflate paths streamed through flate2's 32 KiB read/write wrappers. They now hand the codec the whole chunk in one call, into a buffer sized up front (~5% on chunked writes). This also fixes a silent short read: the streaming reader returned a truncated stream's bytes without an error; a truncated chunk is now DecompressionError. In clawhdf5-filters, output longer than the stated size is now an error rather than silently cut off. CI: ci-test.sh lints and tests the zlib-ng path, and fails if a C-building crate (*-sys, cc, cmake) enters a core crate's default dependency tree. The arm64 job no longer installs cmake. Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
clawhdf5-format
Pure-Rust HDF5 binary format parsing and writing — no C dependencies.
Features
- Zero-copy superblock, object header, and B-tree parsing
- Chunked dataset read/write with filter pipelines
no_stdsupport (disablestdfeature)- Optional parallel reads via Rayon
- SHA-256 provenance tracking
Usage
use clawhdf5_format::Superblock;
let data = std::fs::read("data.h5").unwrap();
let sb = Superblock::from_bytes(&data).unwrap();
println!("HDF5 version {}.{}", sb.version_major(), sb.version_minor());
License
MIT