xoshiro128

A fast, seedable, non-cryptographic, pseudorandom number generator for TypeScript.

import { xoshiro128 } from "xoshiro128";

// seed with 1234
const rng = xoshiro128(1234);

// always the same result
console.assert(rng.random() === 0.05153296561911702);
console.assert(rng.random() === 0.5920798229053617);
console.assert(rng.random() === 0.8060240163467824);

Algorithms

xoshiro128

This library implements xoshiro128 pseudorandom number generators (PRNGs) designed and implemented in C by David Blackman and Sebastiano Vigna.

• xoshiro128++
• xoshiro128**
• xoshiro128+

The default algorithm of this library is xoshiro128**. For more information about xoshiro128 PRNGs, see: https://prng.di.unimi.it/

MurmurHash3

For hashing strings, this library uses 32-bit (x86) version of MurmurHash3 designed and implemented in C++ by Austin Appleby. splitmix32 which is used this library to seed xoshiro128 PRNGs also uses MurmurHash3's finalization step.

Performance

Some benchmarks on Deno (V8) show that this implementation of xoshiro128 PRNGs is as fast as Math.random() or even faster in some cases.

Call .random() 1,000 times

deno bench benches/random

Results on GitHub Actions:

| Algorithm | Average | Min … Max | P75 | P99 | P995 | | --------------- | -------- | ------------------- | -------- | -------- | -------- | | Math.random() | 11.19 µs | 10 µs … 875.52 µs | 10.7 µs | 19.4 µs | 95.8 µs | | xoshiro128++ | 8.61 µs | 8.3 µs … 404.51 µs | 8.7 µs | 10.4 µs | 10.9 µs | | xoshiro128** | 8.59 µs | 8.3 µs … 329.31 µs | 8.5 µs | 9 µs | 10.6 µs | | xoshiro128+ | 8.63 µs | 8.3 µs … 381.91 µs | 8.6 µs | 10.5 µs | 10.9 µs |

cpu: Intel(R) Xeon(R) Platinum 8272CL CPU @ 2.60GHz
runtime: deno 1.35.2 (x86_64-unknown-linux-gnu)

file:///home/runner/work/xoshiro128/xoshiro128/benches/random/internal/xoshiro128plus_bench.ts
benchmark                        time (avg)             (min … max)       p75       p99      p995
------------------------------------------------------------------- -----------------------------
benchXoshiro128PlusInternal       3.89 µs/iter        (3.86 µs … 4 µs)    3.9 µs      4 µs      4 µs

file:///home/runner/work/xoshiro128/xoshiro128/benches/random/internal/xoshiro128plusplus_bench.ts
benchmark                            time (avg)             (min … max)       p75       p99      p995
----------------------------------------------------------------------- -----------------------------
benchXoshiro128PlusPlusInternal       3.39 µs/iter      (3.36 µs … 3.6 µs)   3.39 µs    3.6 µs    3.6 µs

file:///home/runner/work/xoshiro128/xoshiro128/benches/random/internal/xoshiro128starstar_bench.ts
benchmark                            time (avg)             (min … max)       p75       p99      p995
----------------------------------------------------------------------- -----------------------------
benchXoshiro128StarStarInternal       3.37 µs/iter      (3.34 µs … 3.6 µs)   3.37 µs    3.6 µs    3.6 µs

file:///home/runner/work/xoshiro128/xoshiro128/benches/random/math_bench.ts
benchmark      time (avg)             (min … max)       p75       p99      p995
------------------------------------------------- -----------------------------
benchMath      11.19 µs/iter     (10 µs … 875.52 µs)   10.7 µs   19.4 µs   95.8 µs

file:///home/runner/work/xoshiro128/xoshiro128/benches/random/random/float_bench.ts
benchmark                       time (avg)             (min … max)       p75       p99      p995
------------------------------------------------------------------ -----------------------------
benchXoshiro128RandomFloat        8.6 µs/iter    (8.4 µs … 409.61 µs)    8.5 µs   10.6 µs     11 µs

file:///home/runner/work/xoshiro128/xoshiro128/benches/random/random/random_bench.ts
benchmark                  time (avg)             (min … max)       p75       p99      p995
------------------------------------------------------------- -----------------------------
benchXoshiro128Random       8.61 µs/iter    (8.3 µs … 346.81 µs)    8.5 µs   10.6 µs     11 µs

file:///home/runner/work/xoshiro128/xoshiro128/benches/random/xoshiro128plus_bench.ts
benchmark                time (avg)             (min … max)       p75       p99      p995
----------------------------------------------------------- -----------------------------
benchXoshiro128Plus       8.63 µs/iter    (8.3 µs … 381.91 µs)    8.6 µs   10.5 µs   10.9 µs

file:///home/runner/work/xoshiro128/xoshiro128/benches/random/xoshiro128plusplus_bench.ts
benchmark                    time (avg)             (min … max)       p75       p99      p995
--------------------------------------------------------------- -----------------------------
benchXoshiro128PlusPlus       8.61 µs/iter    (8.3 µs … 404.51 µs)    8.7 µs   10.4 µs   10.9 µs

file:///home/runner/work/xoshiro128/xoshiro128/benches/random/xoshiro128starstar_bench.ts
benchmark                    time (avg)             (min … max)       p75       p99      p995
--------------------------------------------------------------- -----------------------------
benchXoshiro128StarStar       8.59 µs/iter    (8.3 µs … 329.31 µs)    8.5 µs      9 µs   10.6 µs

Shuffle an array of 1,000,000 elements

deno bench benches/shuffle

Results on GitHub Actions:

| Algorithm | Average | Min … Max | P75 | P99 | P995 | | --------------- | -------- | ------------------- | -------- | -------- | -------- | | Math.random() | 17.99 ms | 17.57 ms … 19.38 ms | 18.08 ms | 19.38 ms | 19.38 ms | | xoshiro128++ | 19.03 ms | 18.69 ms … 20.56 ms | 19.03 ms | 20.56 ms | 20.56 ms | | xoshiro128** | 17.35 ms | 16.9 ms … 19.54 ms | 17.45 ms | 19.54 ms | 19.54 ms | | xoshiro128+ | 16.48 ms | 16.32 ms … 18.44 ms | 16.47 ms | 18.44 ms | 18.44 ms |

cpu: Intel(R) Xeon(R) Platinum 8272CL CPU @ 2.60GHz
runtime: deno 1.35.2 (x86_64-unknown-linux-gnu)

file:///home/runner/work/xoshiro128/xoshiro128/benches/shuffle/internal/xoshiro128plus_bench.ts
benchmark                               time (avg)             (min … max)       p75       p99      p995
-------------------------------------------------------------------------- -----------------------------
benchShuffleXoshiro128PlusInternal      13.57 ms/iter   (13.38 ms … 14.34 ms)  13.65 ms  14.34 ms  14.34 ms

file:///home/runner/work/xoshiro128/xoshiro128/benches/shuffle/internal/xoshiro128plusplus_bench.ts
benchmark                                   time (avg)             (min … max)       p75       p99      p995
------------------------------------------------------------------------------ -----------------------------
benchShuffleXoshiro128PlusPlusInternal      14.02 ms/iter   (13.92 ms … 15.42 ms)  13.97 ms  15.42 ms  15.42 ms

file:///home/runner/work/xoshiro128/xoshiro128/benches/shuffle/internal/xoshiro128starstar_bench.ts
benchmark                                   time (avg)             (min … max)       p75       p99      p995
------------------------------------------------------------------------------ -----------------------------
benchShuffleXoshiro128StarStarInternal      13.87 ms/iter    (13.7 ms … 14.76 ms)  13.97 ms  14.76 ms  14.76 ms

file:///home/runner/work/xoshiro128/xoshiro128/benches/shuffle/math_bench.ts
benchmark             time (avg)             (min … max)       p75       p99      p995
-------------------------------------------------------- -----------------------------
benchShuffleMath      17.99 ms/iter   (17.57 ms … 19.38 ms)  18.08 ms  19.38 ms  19.38 ms

file:///home/runner/work/xoshiro128/xoshiro128/benches/shuffle/random/random_bench.ts
benchmark                         time (avg)             (min … max)       p75       p99      p995
-------------------------------------------------------------------- -----------------------------
benchShuffleXoshiro128Random      20.12 ms/iter   (19.83 ms … 22.45 ms)  20.12 ms  22.45 ms  22.45 ms

file:///home/runner/work/xoshiro128/xoshiro128/benches/shuffle/random/uniform_bench.ts
benchmark                                time (avg)             (min … max)       p75       p99      p995
--------------------------------------------------------------------------- -----------------------------
benchShuffleXoshiro128RandomUniform      32.12 ms/iter   (31.64 ms … 33.05 ms)   32.2 ms  33.05 ms  33.05 ms

file:///home/runner/work/xoshiro128/xoshiro128/benches/shuffle/xoshiro128plus_bench.ts
benchmark                       time (avg)             (min … max)       p75       p99      p995
------------------------------------------------------------------ -----------------------------
benchShuffleXoshiro128Plus      16.48 ms/iter   (16.32 ms … 18.44 ms)  16.47 ms  18.44 ms  18.44 ms

file:///home/runner/work/xoshiro128/xoshiro128/benches/shuffle/xoshiro128plusplus_bench.ts
benchmark                           time (avg)             (min … max)       p75       p99      p995
---------------------------------------------------------------------- -----------------------------
benchShuffleXoshiro128PlusPlus      19.03 ms/iter   (18.69 ms … 20.56 ms)  19.03 ms  20.56 ms  20.56 ms

file:///home/runner/work/xoshiro128/xoshiro128/benches/shuffle/xoshiro128starstar_bench.ts
benchmark                           time (avg)             (min … max)       p75       p99      p995
---------------------------------------------------------------------- -----------------------------
benchShuffleXoshiro128StarStar      17.35 ms/iter    (16.9 ms … 19.54 ms)  17.45 ms  19.54 ms  19.54 ms

Usage

Generate

import { xoshiro128 } from "xoshiro128";

// seed with 1234
const rng = xoshiro128(1234);

// generate random numbers in [0, 1)
console.assert(rng.random() === 0.4488106195349246);
console.assert(rng.random() === 0.6467702996451408);
console.assert(rng.random() === 0.3171623020898551);

Seed

import { xoshiro128 } from "xoshiro128";

// number
xoshiro128(1234);

// default: seed = 0
xoshiro128();

// string: seed = hash("hello") = 3619887497
xoshiro128("hello");

// random seed
xoshiro128({ random: true });

State

import { xoshiro128 } from "xoshiro128";

const rng = xoshiro128(1234);

// save state
const state = rng.save();

// restore state
rng.restore(state);

// initialize with state
const rng2 = xoshiro128(state);

Algorithm

import { Kind, xoshiro128 } from "xoshiro128";

// xoshiro128** (default)
const starstar = xoshiro128(1234, Kind.StarStar /* "xoshiro128starstar" */);
// xoshiro128++
const plusplus = xoshiro128(1234, Kind.PlusPlus /* "xoshiro128plusplus" */);
// xoshiro128+
const plus = xoshiro128(1234, Kind.Plus /* "xoshiro128plus" */);

console.assert(starstar.random() === 0.4488106195349246);
console.assert(plusplus.random() === 0.05153296561911702);
console.assert(plus.random() === 0.41102893161587417);

Low-level API

import { xoshiro128 } from "xoshiro128";

const rng = xoshiro128(1234);

// generate 32-bit unsigned integer
console.assert(rng.next() === 1927626933);
console.assert(rng.next() === 2777857285);
console.assert(rng.next() === 1362201715);

// jump ahead by 2^64 steps
rng.jump();

// jump ahead by 2^96 steps
rng.longJump();

High-level API (xoshiro128/random)

import { random } from "xoshiro128/random";

// default: 0
random.reset(1234);

// generate 10 random integers in [1, 100]
for (const n of random.iter(10).int(1, 100)) {
    console.log(n);
}

// integer in [1, 100]
random.int(1, 100);

// float in [0, 100)
random.float(0, 100);

// true or false
random.boolean();

// string of length 10
random.string(10, "0123456789");

// array of length 10
random.array(["a", "b", "c", "d", "e"], 10);

// pick an element from the array
random.pick(["a", "b", "c", "d", "e"]);

// sample 3 elements from the array without replacement
random.sample(["a", "b", "c", "d", "e"], 3);

// shuffle the array in place
random.shuffle(["a", "b", "c", "d", "e"]);

// shuffle the array and return a new array
random.shuffled(["a", "b", "c", "d", "e"]);

// save state
const state = random.save();

// restore state
random.restore(state);

// clone
const clone = random.clone();

Deno

xoshiro128:

import { xoshiro128 } from "https://deno.land/x/xoshiro128/mod.ts";

xoshiro128/random:

import { random } from "https://deno.land/x/xoshiro128/random.ts";

Development

This library uses Deno for development.

Build

To build the npm package (0.0.0 for example):

deno run -A scripts/build_npm.ts 0.0.0

Test

To run tests:

deno test

Benchmark

To run benchmarks:

deno bench

License

Licensed under either of

• Apache License, Version 2.0 (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
• MIT License (LICENSE-MIT or http://opensource.org/licenses/MIT)

at your option.

Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.