✨ feat(xoroshiro128plus): First draft.

Missing longJump method.

src/index.js

@@ -1,12 +1,16 @@
 import nextFloat from './nextFloat';
+import nextInt32 from './nextInt32';
 import nextUint64 from './nextUint64';
 import splitmix64 from './splitmix64';
+import xoroshiro128plus from './xoroshiro128plus';
 
 /* eslint import/no-anonymous-default-export: [2, {"allowObject": true}] */
 export default {
 	nextFloat,
+	nextInt32,
 	nextUint64,
 	splitmix64,
+	xoroshiro128plus,
 };
 
-export {nextFloat, nextUint64, splitmix64};
+export {nextFloat, nextInt32, nextUint64, splitmix64, xoroshiro128plus};

src/xoroshiro128plus.js

@@ -0,0 +1,62 @@
+import assert from 'assert';
+import {rotl64, get64, add64, xor64, shl64} from '@aureooms/js-uint64';
+
+export default function xoroshiro128plus(seed, options) {
+	return new XoRoShiRo128Plus(seed, options);
+}
+
+class XoRoShiRo128Plus {
+	constructor(seed, {a, b, c, JUMP}) {
+		this.a = a || 24;
+		this.b = b || 16;
+		this.c = c || 37;
+		this.JUMP = JUMP || [0xd8f554a5, 0xdf900294, 0x4b3201fc, 0x170865df];
+		this.p = 0;
+		this.z = 0;
+		this.s0 = get64(seed[0], seed[1]);
+		this.s1 = get64(seed[2], seed[3]);
+	}
+
+	next() {
+		if (this.p === 0) {
+			this.p = 1;
+			const [value, z] = add64(this.s0, this.s1);
+			this.z = z;
+			return {value, done: false};
+		}
+
+		this.p = 0;
+		const s0 = this.s0;
+		const s1 = xor64(s0, this.s1);
+		this.s0 = xor64(rotl64(s0, this.a), xor64(s1, shl64(s1, this.b)));
+		this.s1 = rotl64(s1, this.c);
+		return {value: this.z, done: false};
+	}
+
+	/**
+	 * This is the jump function for the generator. It is equivalent
+	 * to 2^64 calls to next(); it can be used to generate 2^64
+	 * non-overlapping subsequences for parallel computations.
+	 */
+	jump() {
+		assert(this.p === 0);
+
+		let s0 = get64(0, 0);
+		let s1 = get64(0, 0);
+
+		for (const jump of this.JUMP) {
+			for (let b = 0; b < 32; ++b) {
+				if (jump & (1 << b)) {
+					s0 = xor64(s0, this.s0);
+					s1 = xor64(s1, this.s1);
+				}
+
+				this.next();
+				this.next();
+			}
+		}
+
+		this.s0 = s0;
+		this.s1 = s1;
+	}
+}

test/src/xoroshiro128plus.js

@@ -0,0 +1,73 @@
+import test from 'ava';
+
+import {get64} from '@aureooms/js-uint64';
+
+import {splitmix64, xoroshiro128plus, nextInt32, nextUint64} from '../../src';
+
+test('Example found at https://github.com/dgryski/go-xoroshiro/blob/ea5ca0291510c1f8b16321d610ae73e1006d499f/xoro_test.go#L28', (t) => {
+	const prng = xoroshiro128plus([0, 1, 0, 2], {a: 55, b: 14, c: 36});
+
+	t.deepEqual(nextUint64(prng), get64(0x00000000, 0x00000003)); // 3
+	t.deepEqual(nextUint64(prng), get64(0x00800030, 0x0000c003)); // 36029003177443331
+	t.deepEqual(nextUint64(prng), get64(0x01184060, 0x38000363)); // 78883775479546723
+	t.deepEqual(nextUint64(prng), get64(0xa080fe50, 0x30c4c366)); // 11565523463456473958
+	t.deepEqual(nextUint64(prng), get64(0x3ae0e84f, 0x181c8404)); // 4242646275387589636
+	t.deepEqual(nextUint64(prng), get64(0x03902839, 0x17940944)); // 256749404433942852
+	t.deepEqual(nextUint64(prng), get64(0x98dcc1f0, 0x6360888c)); // 11014892026844973196
+	t.deepEqual(nextUint64(prng), get64(0x7db94a02, 0x5d95c80f)); // 9059353499452950543
+	t.deepEqual(nextUint64(prng), get64(0x77508804, 0x6d70b290)); // 8597521241247625872
+	t.deepEqual(nextUint64(prng), get64(0x412422d9, 0x4084790d)); // 4693915028112570637
+});
+
+test('Example found at https://github.com/dgryski/go-xoroshiro/blob/ea5ca0291510c1f8b16321d610ae73e1006d499f/xoro_test.go#L47', (t) => {
+	const prng = xoroshiro128plus(
+		[0x0916df85, 0x1e2aee44, 0x9ade0f09, 0xffca1bc4],
+		{
+			a: 55,
+			b: 14,
+			c: 36,
+			JUMP: [0xeba5facb, 0xbeac0467, 0x86aa9922, 0xd86b048b],
+		},
+	);
+
+	prng.jump();
+	t.deepEqual(nextUint64(prng), get64(0x658bac67, 0x42f1cb34)); // 7317131579098254132
+	prng.jump();
+	t.deepEqual(nextUint64(prng), get64(0x7ea22887, 0x3c5d2ad5)); // 9124900356304480981
+	prng.jump();
+	t.deepEqual(nextUint64(prng), get64(0xe794ec98, 0xaebcd8bc)); // 16687222659825326268
+	prng.jump();
+	t.deepEqual(nextUint64(prng), get64(0x93e0f50d, 0x5d924d3a)); // 10655786156111842618
+	prng.jump();
+	t.deepEqual(nextUint64(prng), get64(0x0555abbe, 0x490eb380)); // 384402176967881600
+	prng.jump();
+	t.deepEqual(nextUint64(prng), get64(0x1e2935c4, 0x3d1ceffa)); // 2173327412138143738
+	prng.jump();
+	t.deepEqual(nextUint64(prng), get64(0xc94b9bd3, 0x583ae4dd)); // 14504858356897473757
+	prng.jump();
+	t.deepEqual(nextUint64(prng), get64(0x426bc5ee, 0x5b3a4f93)); // 4786136656534720403
+	prng.jump();
+	t.deepEqual(nextUint64(prng), get64(0x2ac1f1af, 0xddd342bf)); // 3081009357741310655
+	prng.jump();
+	t.deepEqual(nextUint64(prng), get64(0x3884d3ed, 0xd6ffd586)); // 4072612981517571462
+});
+
+test('Example found at https://github.com/dgryski/go-xoroshiro/blob/ea5ca0291510c1f8b16321d610ae73e1006d499f/xoro_test.go#L80', (t) => {
+	const seed = splitmix64([0x0ddc0ffe, 0xebadf00d]);
+
+	const prng = xoroshiro128plus(
+		[nextInt32(seed), nextInt32(seed), nextInt32(seed), nextInt32(seed)],
+		{a: 55, b: 14, c: 36},
+	);
+
+	t.deepEqual(nextUint64(prng), get64(0xa3f4ee8f, 0x1df50a08)); // 11814330020949985800
+	t.deepEqual(nextUint64(prng), get64(0xa3febba4, 0x5a9ce9c5)); // 11817088786836023749
+	t.deepEqual(nextUint64(prng), get64(0x16f4c81d, 0x130768eb)); // 1654166990350674155
+	t.deepEqual(nextUint64(prng), get64(0xc3da8db5, 0x1d9cc8ea)); // 14112748191344281834
+	t.deepEqual(nextUint64(prng), get64(0x3b8315d6, 0xf1f63305)); // 4288295283113472773
+	t.deepEqual(nextUint64(prng), get64(0x747636fe, 0x553bb5ca)); // 8391955421631067594
+	t.deepEqual(nextUint64(prng), get64(0x0255d516, 0xf81d9239)); // 168274855724945977
+	t.deepEqual(nextUint64(prng), get64(0x27114eb0, 0xcdd2961f)); // 2815117763357611551
+	t.deepEqual(nextUint64(prng), get64(0xa92195f5, 0x93148843)); // 12187186948608395331
+	t.deepEqual(nextUint64(prng), get64(0x9381f38a, 0x6d63d35c)); // 10629044371437376348
+});