Port wasm solver to C and add regression coverage by Soccera1 · Pull Request #206 · tiagozip/cap

Soccera1 · 2026-03-26T07:58:41Z

What changed

Replaced the Rust WASM solver with a C implementation in wasm/src/c/src/cap_wasm.c, including SHA-256 hashing, hex-prefix target parsing, nonce formatting, and wasm allocator shims.
Removed the old Rust crate under wasm/src/rust and updated the docs/package metadata to describe the solver as C-based WASM.
Tightened the test suite: wasm/src/c/test-regression.cjs became a fixed regression suite, wasm/test/node.js now asserts expected nonces for the full challenge set, and wasm/test/node_odd_difficulty.js verifies the odd-length target case.
Updated wasm/build.js so the build runs the regression suite.

Commit breakdown

629ed2f: Port wasm from Rust to C
978c1f5: Remove Rust code
dee457e: Update tests

This was done as the rust implementation had many external dependencies, and rustc is very difficult to bootstrap. This version has no external dependencies; it can be compiled with -ffreestanding.
I have also done some unscientific testing and this is over 13% faster.

Summary by CodeRabbit

New Features
- Added a full benchmark suite (Node + browser) with runner, browser UI, and an easy local server to compare solver implementations and report speedups.
Documentation
- Updated docs and READMEs to describe the client solver as a C-based WebAssembly implementation.
Tests
- Added regression tests validating solver correctness across multiple challenge cases.
Chores
- Build pipeline updated to produce a C-based WASM solver and related build orchestration.

tiagozip

looks pretty good other than these three minor things! if you can move testing over to bun test and fix these i'll start benchmarking so it can be in prod

wasm/test/node_odd_difficulty.js

wasm/build.js

wasm/src/c/test-regression.cjs

tiagozip · 2026-03-27T17:28:45Z

wasm/build.js

-  fs.rmdirSync(browserOutDir);
-} catch {}
+console.log(`Building C wasm...`);
+execSync(`make -C "${cSrcDir}" clean`, { stdio: "inherit" });


also a nitpick but this should have recursive: true.

- Convert wasm test scripts to `bun test` - Rename test files to `.test.js` - Keep node and browser solver regression coverage

tiagozip · 2026-03-28T11:44:55Z

do you have any benchmarks you can publish?

tiagozip · 2026-03-28T12:35:10Z

this seems to be slower than the current rust solver

Soccera1 · 2026-03-28T13:30:31Z

do you have any benchmarks you can publish?

I've pushed a benchmark. Here are my results.

tiagozip · 2026-03-28T13:41:44Z

is this on web or node/bun?

Soccera1 · 2026-03-28T13:47:58Z

is this on web or node/bun?

bun installed from npm

Soccera1 · 2026-03-28T13:48:34Z

On a Haswell CPU it's even more stark.

tiagozip · 2026-03-28T14:02:39Z

is this on web or node/bun?

bun installed from npm

do you have a web benchmark?

Soccera1 · 2026-03-28T14:03:10Z

I will create one

coderabbitai · 2026-03-28T14:30:14Z

📝 Walkthrough

Walkthrough

Replaces the Rust-based WASM solver with a C-based WASM implementation, adds a Makefile-driven C build, introduces a benchmark suite (Node + browser) comparing C vs Rust baselines, updates build/test flows to run C artifacts, and adjusts docs and tests to reflect the C solver.

Changes

Cohort / File(s)	Summary
Documentation `docs/guide/widget.md`, `docs/guide/workings.md`, `wasm/src/README.md`	Text updated to identify the client-side solver as a C-based WASM solver instead of Rust.
C Solver Source & Build `wasm/src/c/src/cap_wasm.c`, `wasm/src/c/include/cap_wasm.h`, `wasm/src/c/Makefile`	New C implementation: SHA‑256, POW solver, wasm-bindgen-compatible allocator/start, and Makefile targets to build and sync Node/browser .wasm outputs.
Build Pipeline `wasm/build.js`	Replaced Rust/wasm-pack steps with make-based C build and updated test invocation patterns to use Bun tests (`*.test.js`).
Benchmark Suite (Node + Browser) `wasm/benchmark/README.md`, `wasm/benchmark/bench.js`, `wasm/benchmark/browser/bench.js`, `wasm/benchmark/browser/index.html`, `wasm/benchmark/build-artifacts.js`, `wasm/benchmark/serve-browser.js`, `wasm/benchmark/shared.js`, `wasm/benchmark/package.json`, `wasm/benchmark/rust/.gitignore`, `wasm/benchmark/...`	Adds a comprehensive benchmark framework: artifact builders for head (C) and Rust baseline, Node runner, browser runner+UI, shared helpers, docs, and package scripts.
Tests & Regression `wasm/src/c/test-regression.test.js`, `wasm/test/node.test.js`, `wasm/test/node_odd_difficulty.test.js`, `wasm/test/node.js`, `wasm/src/package.json`	New/renamed Bun-based tests exercising Node and browser wrappers; regression tests added for the C solver; removed/rewrote previous standalone script.
Rust Baseline Minor Edits `wasm/benchmark/rust/src/lib.rs`	Whitespace/import reorder only (no semantic change).

Sequence Diagram(s)

sequenceDiagram
  autonumber
  participant Builder as Build Artifacts
  participant Runner as Bench Runner (Node / Browser)
  participant WASM_head as C-based WASM (head)
  participant WASM_rust as Rust WASM (baseline)
  participant UI as Console / Browser UI

  Builder->>Builder: buildHead() (make, produce cap_wasm.wasm + loaders)
  Builder->>Builder: buildRust() (checkout baseline, build rust wasm + loaders)
  Runner->>WASM_head: init() / load solve_pow
  Runner->>WASM_rust: init() / load solve_pow
  Runner->>WASM_head: verifySolver(challengeCases)
  WASM_head-->>Runner: verification result
  Runner->>WASM_rust: verifySolver(challengeCases)
  WASM_rust-->>Runner: verification result
  Runner->>WASM_head: benchmarkSolver(iterations,warmup)
  WASM_head-->>Runner: timings + checksum
  Runner->>WASM_rust: benchmarkSolver(iterations,warmup)
  WASM_rust-->>Runner: timings + checksum
  Runner->>UI: compare checksums, compute speedup, print results

Estimated code review effort

🎯 4 (Complex) | ⏱️ ~60 minutes

Poem

🐰 a little hop of delight

I chewed some bytes and built a crate,
From Rust to C I changed my gait.
Benchmarks hum, the numbers sing—
Wasm wings flap, the results take wing.

🚥 Pre-merge checks | ✅ 2 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 2.22% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately captures the main change: porting the WASM solver from Rust to C and adding regression test coverage. It is clear, specific, and concise.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing Touches

🧪 Generate unit tests (beta)

Create PR with unit tests

_{Comment @coderabbitai help to get the list of available commands and usage tips.}

Soccera1 · 2026-03-28T14:31:38Z

is this on web or node/bun?

bun installed from npm

do you have a web benchmark?

Results are consistent with yours in the web benchmark I created. Not sure why. Maybe the web benchmark is not using AVX2 for my implementation whereas it is for the old one?

Soccera1 · 2026-03-28T14:38:55Z

I've found the issue. With node it's also slower.
However, it's faster with bun.

Soccera1 marked this pull request as ready for review March 26, 2026 09:19

Soccera1 force-pushed the main branch from dee457e to 4cc726a Compare March 26, 2026 09:37

Soccera1 added 3 commits March 26, 2026 20:37

Port wasm from Rust to C

59814b9

Remove Rust code

25a8063

Update tests

c2fc69c

Soccera1 force-pushed the main branch from 4cc726a to c2fc69c Compare March 26, 2026 09:37

tiagozip requested changes Mar 27, 2026

View reviewed changes

wasm/test/node_odd_difficulty.js Outdated Show resolved Hide resolved

wasm/build.js Outdated Show resolved Hide resolved

wasm/src/c/test-regression.cjs Outdated Show resolved Hide resolved

tiagozip reviewed Mar 27, 2026

View reviewed changes

Migrate wasm regression tests to Bun

441726f

- Convert wasm test scripts to `bun test` - Rename test files to `.test.js` - Keep node and browser solver regression coverage

Add wasm benchmark for Rust baseline

859fd6e

Create browser based test

93f7a81

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Soccera1 added 3 commits March 29, 2026 01:51

Fix hardcoded path

488203f

Fix assumed path in regression tests

6422b0b

Reject anything that is not a full non-negative integer in benchmark

41215a1

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Walkthrough

Changes

Sequence Diagram(s)

Estimated code review effort

Poem

❌ Failed checks (1 warning)

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Soccera1 commented Mar 26, 2026 •

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