swaitsandClaude Opus 4.6
777a37d4cd
Decode rewritten with shrinking-slice pattern (split_first/split_at) instead of index arithmetic. Decode zeros 14% faster, decode nonzero flips from 5% behind corncobs to 2% ahead, decode mixed closes to tied. Encode zeros fast path moved before split_at — now tied with cobs (was 6% behind). Code size reduced to 821B (was 869B). Replaced criterion with iai-callgrind for deterministic instruction-count benchmarks via Valgrind. Zero run-to-run variance. Expanded to 162 benchmarks across 9 sizes. ucobs now wins or ties 16 of 18 benchmarks vs corncobs and cobs. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
73 lines
2.8 KiB
Markdown
73 lines
2.8 KiB
Markdown
# Changelog
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## 0.3.1 — 2026-03-31
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### Performance
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- **Decode: rewritten with shrinking-slice pattern** — decode zeros is 14%
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faster (25,018 vs 29,114 instructions at 4 KB), decode nonzero flipped from
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5% behind corncobs to 2% ahead, decode mixed closed from 8% behind to tied.
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ucobs now wins or ties 16 of 18 benchmarks.
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- **Encode zeros: 6% faster** — zero fast path moved before `split_at` calls,
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eliminating per-byte overhead. Now tied with cobs (previously 6% behind).
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- **Code size reduced** — 821 B total (was 869 B). Encode 429 B, decode 392 B.
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### Changed
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- **Replaced criterion with iai-callgrind** — benchmarks now measure
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deterministic instruction counts via Valgrind instead of wall-clock time.
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Zero run-to-run variance. Requires `valgrind` installed.
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- **Expanded benchmark coverage** — 9 payload sizes (0–4096 B) × 3 patterns
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× 3 crates × encode/decode = 162 benchmarks, all running in ~2 minutes.
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- **Code size measurement** added to `just bench` via `just bench-size`.
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- **Mutation testing** added via `cargo-mutants` (`just test-mutants`).
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- Added `mise.toml` for dev tool management.
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## 0.3.0 — 2026-03-31
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### Performance
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- **Encode nonzero/mixed: ~2x faster** — uses const `copy_from_slice` (memcpy at
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runtime) via Rust 1.93's stabilization of const slice methods. Sub-slice scan
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pattern helps LLVM eliminate bounds checks.
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- **Encode zeros: ~50% faster** — fast path skips scan loop overhead for leading
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zero bytes.
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- **Decode zeros: ~4x faster** — batch consecutive `0x01` codes and fill zeros
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via `fill(0)` (memset) instead of per-byte iteration.
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- Encode now wins or ties corncobs on nonzero/mixed workloads.
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- Decode zeros now leads all competitors by 3x.
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### Added
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- `legacy-msrv` feature flag — enables compilation on Rust 1.83+ (e.g. Xtensa
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toolchain) by replacing const `copy_from_slice` with a manual byte loop.
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All other optimizations (sub-slice scan, zero fast path, decode batch fill)
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work without this feature on any supported Rust version.
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### Changed
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- **MSRV bumped from 1.83 to 1.93** — required for const `copy_from_slice`.
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Use the `legacy-msrv` feature for older toolchains.
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- Dev-dependencies updated: `cobs` 0.3 to 0.5, `criterion` 0.5 to 0.8,
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`rand` 0.8 to 0.10.
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## 0.2.0 — 2026-03-30
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### Added
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- `const fn` encode — encode data at compile time with zero runtime cost.
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- Comprehensive documentation with 7 usage examples (basic, buffer sizing,
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framing, stream parsing, compile-time encoding, error handling).
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- Initial encode/decode throughput optimizations.
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### Changed
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- MSRV set to 1.83.
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## 0.1.0 — 2026-03-29
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- Initial release.
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- `no_std`, zero-alloc, `unsafe`-free COBS encoder and decoder.
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- 106 tests: canonical vectors, property-based (proptest), fuzz targets,
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cross-crate interop with `corncobs` and `cobs`.
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