quill-fastsort-ips4o

Parallel comparison-samplesort backend for quill-sort. Portable C++17 build that runs natively on macOS (arm64/x86_64), Linux (x86_64/aarch64) and Windows.

Registered under the quill backend name ips4o. Provides the entry points quill._backends.Ips4oBackend probes for:

sort_i64  sort_u64  sort_i32
sort_u32  sort_f64  sort_f32

Each sorts a contiguous, writable numpy buffer of the matching dtype in place, ascending. The kernel is quillcore::parallel_samplesort — a parallel comparison samplesort: oversample the input, pick K-1 splitters, scatter into globally value-ordered buckets across a thread pool, then sort each bucket independently with no merge step. This is a distinct algorithm family from the radix backend.

• Never-lose: results are identical to np.sort on NaN-free numeric data (verified exhaustively against np.sort across dtypes, sizes and adversarial distributions). NaN is stripped by the Quill dispatcher before any kernel runs.
• Speed: scales with core count and array size on large inputs; falls back to a serial radix sort for small arrays.

Build

pip install .            # needs only a C++17 compiler

The sort kernels are header-only (src/quill_core.hpp, a synced copy of companions/_core/quill_core.hpp — run companions/sync_core.sh after editing the canonical core). No numpy headers or third-party libraries are required.