ucobs/CHANGELOG.md

Changelog

0.3.2 — 2026-04-01

Testing

• Mutation testing: 100% kill rate — 89 mutants tested, 59 caught, 30 unviable (type system rejects them), 0 missed. Uses cargo-mutants v27 with nextest. Added mutants crate for #[mutants::skip] annotations.
• 111 tests (was 106): added block-boundary interop verification against corncobs, exact-fit and too-small decode buffer sizing for the batch zero path.

0.3.1 — 2026-03-31

Performance

• Decode: rewritten with shrinking-slice pattern — decode zeros is 14% faster (25,018 vs 29,114 instructions at 4 KB), decode nonzero flipped from 5% behind corncobs to 2% ahead, decode mixed closed from 8% behind to tied. ucobs now wins or ties 16 of 18 benchmarks.
• Encode zeros: 6% faster — zero fast path moved before split_at calls, eliminating per-byte overhead. Now tied with cobs (previously 6% behind).
• Code size reduced — 821 B total (was 869 B). Encode 429 B, decode 392 B.

Changed

• Replaced criterion with iai-callgrind — benchmarks now measure deterministic instruction counts via Valgrind instead of wall-clock time. Zero run-to-run variance. Requires valgrind installed.
• Expanded benchmark coverage — 9 payload sizes (0–4096 B) × 3 patterns × 3 crates × encode/decode = 162 benchmarks, all running in ~2 minutes.
• Code size measurement added to just bench via just bench-size.
• Mutation testing added via cargo-mutants (just test-mutants).
• Added mise.toml for dev tool management.

0.3.0 — 2026-03-31

Performance

• Encode nonzero/mixed: ~2x faster — uses const copy_from_slice (memcpy at runtime) via Rust 1.93's stabilization of const slice methods. Sub-slice scan pattern helps LLVM eliminate bounds checks.
• Encode zeros: ~50% faster — fast path skips scan loop overhead for leading zero bytes.
• Decode zeros: ~4x faster — batch consecutive 0x01 codes and fill zeros via fill(0) (memset) instead of per-byte iteration.
• Encode now wins or ties corncobs on nonzero/mixed workloads.
• Decode zeros now leads all competitors by 3x.

Added

• legacy-msrv feature flag — enables compilation on Rust 1.83+ (e.g. Xtensa toolchain) by replacing const copy_from_slice with a manual byte loop. All other optimizations (sub-slice scan, zero fast path, decode batch fill) work without this feature on any supported Rust version.

Changed

• MSRV bumped from 1.83 to 1.93 — required for const copy_from_slice. Use the legacy-msrv feature for older toolchains.
• Dev-dependencies updated: cobs 0.3 to 0.5, criterion 0.5 to 0.8, rand 0.8 to 0.10.

0.2.0 — 2026-03-30

Added

• const fn encode — encode data at compile time with zero runtime cost.
• Comprehensive documentation with 7 usage examples (basic, buffer sizing, framing, stream parsing, compile-time encoding, error handling).
• Initial encode/decode throughput optimizations.

Changed

• MSRV set to 1.83.

0.1.0 — 2026-03-29

• Initial release.
• no_std, zero-alloc, unsafe-free COBS encoder and decoder.
• 106 tests: canonical vectors, property-based (proptest), fuzz targets, cross-crate interop with corncobs and cobs.