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Tidy up ALEA RNG code
Not a performance improvement, just something that needed to be done. Slightly simplifies the structure and removes useless functions (changing the seed resets the RNG anyway - it is better to create a new instance instead).
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Даниїл Григор'єв
parent
b3d0e30c07
commit
ae739be484
@ -1,129 +0,0 @@
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// ALEA RNG
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function Mash() {
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var n = 0xefc8249d;
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return function (data) {
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data = data.toString();
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for (var i = 0; i < data.length; i++) {
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n += data.charCodeAt(i);
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var h = 0.02519603282416938 * n;
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n = h >>> 0;
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h -= n;
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h *= n;
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n = h >>> 0;
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h -= n;
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n += h * 0x100000000; // 2^32
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}
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return (n >>> 0) * 2.3283064365386963e-10; // 2^-32
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};
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}
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/**
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* @param {number|string} seed
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*/
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function makeNewRng(seed) {
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// Johannes Baagøe <baagoe@baagoe.com>, 2010
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var c = 1;
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var mash = Mash();
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let s0 = mash(" ");
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let s1 = mash(" ");
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let s2 = mash(" ");
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s0 -= mash(seed);
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if (s0 < 0) {
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s0 += 1;
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}
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s1 -= mash(seed);
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if (s1 < 0) {
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s1 += 1;
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}
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s2 -= mash(seed);
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if (s2 < 0) {
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s2 += 1;
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}
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mash = null;
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var random = function () {
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var t = 2091639 * s0 + c * 2.3283064365386963e-10; // 2^-32
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s0 = s1;
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s1 = s2;
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return (s2 = t - (c = t | 0));
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};
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random.exportState = function () {
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return [s0, s1, s2, c];
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};
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random.importState = function (i) {
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s0 = +i[0] || 0;
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s1 = +i[1] || 0;
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s2 = +i[2] || 0;
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c = +i[3] || 0;
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};
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return random;
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}
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export class RandomNumberGenerator {
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/**
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*
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* @param {number|string=} seed
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*/
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constructor(seed) {
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this.internalRng = makeNewRng(seed || Math.random());
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}
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/**
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* Re-seeds the generator
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* @param {number|string} seed
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*/
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reseed(seed) {
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this.internalRng = makeNewRng(seed || Math.random());
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}
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/**
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* @returns {number} between 0 and 1
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*/
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next() {
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return this.internalRng();
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}
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/**
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* Random choice of an array
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* @param {array} array
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*/
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choice(array) {
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const index = this.nextIntRange(0, array.length);
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return array[index];
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}
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/**
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* @param {number} min
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* @param {number} max
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* @returns {number} Integer in range [min, max[
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*/
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nextIntRange(min, max) {
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assert(Number.isFinite(min), "Minimum is no integer");
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assert(Number.isFinite(max), "Maximum is no integer");
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assert(max > min, "rng: max <= min");
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return Math.floor(this.next() * (max - min) + min);
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}
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/**
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* @param {number} min
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* @param {number} max
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* @returns {number} Number in range [min, max[
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*/
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nextRange(min, max) {
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assert(max > min, "rng: max <= min");
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return this.next() * (max - min) + min;
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}
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/**
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* Updates the seed
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* @param {number} seed
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*/
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setSeed(seed) {
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this.internalRng = makeNewRng(seed);
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}
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}
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81
src/js/core/rng.ts
Normal file
81
src/js/core/rng.ts
Normal file
@ -0,0 +1,81 @@
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class Alea {
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private n = 0xefc8249d;
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private c = 1;
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private s0: number;
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private s1: number;
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private s2: number;
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constructor(seed: string) {
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// Johannes Baagøe <baagoe@baagoe.com>, 2010
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this.s0 = this.mash(" ");
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this.s1 = this.mash(" ");
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this.s2 = this.mash(" ");
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this.s0 -= this.mash(seed);
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if (this.s0 < 0) {
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this.s0 += 1;
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}
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this.s1 -= this.mash(seed);
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if (this.s1 < 0) {
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this.s1 += 1;
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}
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this.s2 -= this.mash(seed);
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if (this.s2 < 0) {
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this.s2 += 1;
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}
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}
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protected next(): number {
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const t = 2091639 * this.s0 + this.c * 2.3283064365386963e-10; // 2^-32
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this.s0 = this.s1;
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this.s1 = this.s2;
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return (this.s2 = t - (this.c = t | 0));
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}
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private mash(data: string): number {
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for (let i = 0; i < data.length; i++) {
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this.n += data.charCodeAt(i);
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let h = 0.02519603282416938 * this.n;
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this.n = h >>> 0;
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h -= this.n;
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h *= this.n;
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this.n = h >>> 0;
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h -= this.n;
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this.n += h * 0x100000000; // 2^32
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}
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return (this.n >>> 0) * 2.3283064365386963e-10; // 2^-32
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}
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}
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export class RandomNumberGenerator extends Alea {
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constructor(seed: string | number = Math.random()) {
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super(seed.toString());
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}
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/**
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* Random choice of an array
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*/
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choice<T>(array: T[]): T {
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const index = this.nextIntRange(0, array.length);
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return array[index];
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}
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/**
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* @returns Integer in range [min, max]
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*/
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nextIntRange(min: number, max: number): number {
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assert(Number.isFinite(min), "Minimum is no integer");
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assert(Number.isFinite(max), "Maximum is no integer");
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assert(max > min, "rng: max <= min");
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return Math.floor(this.next() * (max - min) + min);
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}
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/**
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* @returns Number in range [min, max]
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*/
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nextRange(min: number, max: number): number {
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assert(max > min, "rng: max <= min");
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return this.next() * (max - min) + min;
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}
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}
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