Native math backend (libx07_math)

This document describes the native implementation strategy for the external math package (x07-ext-math).

What is pinned

The C ABI between x07c-emitted code and the math backend is pinned by:

• crates/x07c/include/x07_math_abi_v1.h

Backends must export the symbols declared in that header.

Required runtime hooks

The math backend does not own memory. It allocates result bytes using the X07 runtime allocator:

• ev_bytes ev_bytes_alloc(uint32_t len)

The backend may trap (abort) on invariant violations:

• void ev_trap(int32_t code)

Building

Use:

• scripts/build_ext_math.sh

This builds crates/x07-math-native and stages the outputs into:

• deps/x07/libx07_math.a
• deps/x07/include/x07_math_abi_v1.h

The current in-repo backend (crates/x07-math-native) implements the libm, formatting, and parsing surface with:

• libm (pure Rust libm)
• ryu (formatting)
• lexical-core (parsing)

For the deterministic-vendoring strategy and recommended pinned upstreams, see vendor guidance.

CI

• scripts/ci/check_math_smoke.sh

Runs the math smoke suites; the math-f64-libm-smoke.json suite exercises this native backend under run-os.