This crate provides common psuedo random number generators written in pure Rust, which include:

cargo add tiny_prng

• prepare a seed with a certain way
• construct a generator
• generate pseudo random number with generate()

use tiny_prng::xorshift::Xorshift64;
use std::time::SystemTime;

const MODV: u128 = 19937 * 273;
const MODS: usize = 11;

fn main() {
    let now = SystemTime::now().duration_since(SystemTime::UNIX_EPOCH).unwrap().as_nanos();
    /// Note: That's good to refer additional source(s) to calculate the seed
    let seed = ((now % MODV) << MODS) + now;
    /// A generator must be a mutable because its internal state alters at the random number generation.
    let mut x = Xorshift64::with_seed(seed as u64);
    println!("{} {} {}", x.generate(), x.generate(), x.generate());
}

You can use tiny_prng in WASM. Two types of usage patterns are supported.

• Link the crate and build the code with wasm32-wasip2 target (and run it with wasmtime and so on.)
• Call WASM functions from JavaScript code

For web developers who need to generate many pseudo random numbers, we also provide the npm package tiny-prng-wasm. Install it as follows:

npm install tiny-prng-wasm

In the npm package, three PRNGs (and one mode for each) are supported:

• Pcg (PCG-XSL-RR-128/64)
• Mt64 (MT19937_64)
• Xorshift64 (Xorshift64)

For the JavaScript API, see the npm package's README.

Any core routines in the library can generate a pseudo random number within 100 milliseconds with consumer grade 64-bit computers (e.g. low-end smartphones with ARMv9 chipset, laptop PCs with Tiger Lake Generation Celeron, etc.), although you need to instantiate the generator with seed before it works.

See the benchmarking result for 10 million instructions of pseudo random number generation:

user@localhost tiny_prng $  cargo bench  | grep -v ignored
# (output omitted...)
running 31 tests
test mt64::tests::bench_mt19937_10mil          ... bench:   7,660,233.30 ns/iter (+/- 43,981.22)
test mt::tests::bench_mt19937_32_10mil         ... bench:   9,339,750.10 ns/iter (+/- 415,492.15)
test pcg::tests::bench_pcgxshrr6432_10mil      ... bench:   9,416,045.80 ns/iter (+/- 589,289.98)
test pcg::tests::bench_pcgxslrr12864_10mil     ... bench:  15,627,133.30 ns/iter (+/- 260,361.14)
test xorshift::tests::bench_xorshift1024_10mil ... bench:  23,095,120.80 ns/iter (+/- 7,339,056.80)
test xorshift::tests::bench_xorshift64_10mil   ... bench:  18,749,149.90 ns/iter (+/- 186,877.62)

Execution environment:

• OS: macOS Sequoia 15.5
• CPU: arm64 (Apple M1)
• Memory: 8GB

As the simplest web benchmarking environment, you can try the online benchmarking in your browser.

Simply run make under the wasm_web directory and open http://localhost:8080.

Tiny PRNG Wasm contributors