Hedgehog SplitMix64 WASM

High-performance WebAssembly implementation of the SplitMix64 splittable pseudorandom number generator.

Overview

This is a language-agnostic WebAssembly module that provides:

• SplitMix64 algorithm: High-quality 64-bit pseudorandom number generation
• Splittable streams: Create independent random number generators
• Deterministic: Same seed always produces same sequence
• High performance: ~6x faster than pure JavaScript implementations

Building

Requires wasm-pack:

# From project root
bin/build-wasm

# Or manually
cd hedgehog-splitmix-wasm
wasm-pack build --target web --out-dir pkg

Usage

From TypeScript/JavaScript

import { Seed } from './hedgehog-splitmix-wasm/pkg';

// Create seed from number
const seed = new Seed(42);

// Generate random values
const { value, seed: nextSeed } = seed.next_u64();
const { value: bounded, seed: nextSeed2 } = seed.next_bounded(100);
const { value: boolean, seed: nextSeed3 } = seed.next_bool();

// Split into independent streams
const { left, right } = seed.split();

From other languages

The WASM module can be imported and used from any language that supports WebAssembly:

• Python (with wasmtime-py or similar)
• Go (with wasmtime-go)
• Rust (with wasmtime)
• C/C++ (with WASI)
• And many others

API

Seed

• new Seed(value: u64) - Create seed from number
• Seed.from_parts(state: u64, gamma: u64) - Create from components
• seed.state - Get state component
• seed.gamma - Get gamma component
• seed.next_u64() - Generate next u64 and new seed
• seed.next_bounded(bound: u64) - Generate bounded value [0, bound)
• seed.next_bool() - Generate boolean
• seed.split() - Split into two independent seeds

Algorithm Details

Based on the SplitMix64 algorithm with these key properties:

• Period: 2^64 for each generator stream
• Quality: Passes statistical randomness tests
• Splitting: Creates mathematically independent streams
• Performance: Optimized for speed and small WASM binary size

Constants

• Golden ratio: 0x9e3779b97f4a7c15
• Mix multipliers: 0xbf58476d1ce4e5b9, 0x94d049bb133111eb

License

BSD-3-Clause (same as parent project)