Merge pull request #435 from akashic-games/update-xorshift

feat: xorshift のリファレンス実装を更新

Author: yu-ogi

.github/workflows/reftest.yml

@@ -9,13 +9,11 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest]
-        node: [14.x, 16.x]
+        node: [16.x, 18.x]
     steps:
       - uses: actions/setup-node@v3
         with:
           node-version: ${{ matrix.node }}
-      - name: Use npm@7
-        run: npm i -g npm@7 --registry=https://registry.npmjs.org
       - name: Checkout akashic-engine repository
         uses: actions/checkout@v3
         with:

.github/workflows/release.yml

@@ -6,7 +6,7 @@ on:
       - main
 
 env:
-  NODE_VERSION: 16
+  NODE_VERSION: 18
 
 jobs:
   release:

.github/workflows/test.yml

@@ -9,7 +9,7 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest, windows-latest]
-        node: [14.x, 16.x]
+        node: [16.x, 18.x]
     steps:
       - name: Checkout code
         uses: actions/checkout@v3

CHANGELOG.md

@@ -1,7 +1,11 @@
 # ChangeLog
 
-## unreleased changes
+## 3.10.0
 * @akashic/game-configuration@1.9.0 に追従
+* xorshift のリファレンス実装を更新
+
+### ゲーム開発者への影響
+* xorshift のリファレンス実装の更新により、既存の playlog の再現性が失われる可能性があります。
 
 ## 3.9.3
 機能追加

package-lock.json

@@ -1,6 +1,6 @@
 {
   "name": "@akashic/akashic-engine",
-  "version": "3.9.3",
+  "version": "3.10.0",
   "description": "The core library of Akashic Engine",
   "main": "index.js",
   "dependencies": {
@@ -33,7 +33,7 @@
     "ts-jest": "^29.0.0",
     "typedoc": "^0.23.0",
     "typescript": "^4.7.4",
-    "xorshift": "0.2.0"
+    "xorshift": "1.2.0"
   },
   "scripts": {
     "prepare": "npm run build && npm run doc",

package.json

@@ -4,48 +4,43 @@
 // Arranged by DWANGO Co., Ltd.
 
 export class Xorshift {
-	private _state0U!: number;
-	private _state0L!: number;
-	private _state1U!: number;
-	private _state1L!: number;
+	private _state0U: number;
+	private _state0L: number;
+	private _state1U: number;
+	private _state1L: number;
 
 	static deserialize(ser: XorshiftSerialization): Xorshift {
-		const ret = new Xorshift(0);
-		ret._state0U = ser._state0U;
-		ret._state0L = ser._state0L;
-		ret._state1U = ser._state1U;
-		ret._state1L = ser._state1L;
+		const ret = new Xorshift([ser._state0U, ser._state0L, ser._state1U, ser._state1L]);
 		return ret;
 	}
 
-	constructor(seed: number) {
-		this.initState(seed);
+	constructor(seed: number | [number, number, number, number]) {
+		const seeds = Array.isArray(seed) ? seed : this.generateSeeds(seed);
+
+		this._state0U = seeds[0] | 0;
+		this._state0L = seeds[1] | 0;
+		this._state1U = seeds[2] | 0;
+		this._state1L = seeds[3] | 0;
 	}
 
-	// シード値が1つの場合にどのようにして初期状態を定義するかは特に定まっていない
-	// このコードはロジック的な裏付けは無いが採用例が多いために採用した
-	// 以下採用例
-	// http://meme.biology.tohoku.ac.jp/klabo-wiki/index.php?cmd=read&page=%B7%D7%BB%BB%B5%A1%2FC%2B%2B#y919a7e1
-	// http://hexadrive.sblo.jp/article/63660775.html
-	// http://meme.biology.tohoku.ac.jp/students/iwasaki/cxx/random.html#xorshift
 	initState(seed: number): void {
-		const factor = 1812433253;
-		seed = factor * (seed ^ (seed >> 30)) + 1;
-		this._state0U = seed;
-		seed = factor * (seed ^ (seed >> 30)) + 2;
-		this._state0L = seed;
-		seed = factor * (seed ^ (seed >> 30)) + 3;
-		this._state1U = seed;
-		seed = factor * (seed ^ (seed >> 30)) + 4;
-		this._state1L = seed;
+		const seeds = this.generateSeeds(seed);
+		this._state0L = seeds[0] | 0;
+		this._state0U = seeds[1] | 0;
+		this._state1L = seeds[2] | 0;
+		this._state1U = seeds[3] | 0;
 	}
 
-	randomInt(): number[] {
+	randomInt(): [number, number] {
 		let s1U = this._state0U;
 		let s1L = this._state0L;
 		const s0U = this._state1U;
 		const s0L = this._state1L;
 
+		const sumL = (s0L >>> 0) + (s1L >>> 0);
+		const resU = (s0U + s1U + ((sumL / 2) >>> 31)) >>> 0;
+		const resL = sumL >>> 0;
+
 		this._state0U = s0U;
 		this._state0L = s0L;
 
@@ -64,14 +59,14 @@ export class Xorshift {
 		t1U = s1U ^ s0U;
 		t1L = s1L ^ s0L;
 
-		const a2 = 17;
+		const a2 = 18;
 		const m2 = 0xffffffff >>> (32 - a2);
 		t2U = s1U >>> a2;
 		t2L = (s1L >>> a2) | ((s1U & m2) << (32 - a2));
 		t1U = t1U ^ t2U;
 		t1L = t1L ^ t2L;
 
-		const a3 = 26;
+		const a3 = 5;
 		const m3 = 0xffffffff >>> (32 - a3);
 		t2U = s0U >>> a3;
 		t2L = (s0L >>> a3) | ((s0U & m3) << (32 - a3));
@@ -81,16 +76,14 @@ export class Xorshift {
 		this._state1U = t1U;
 		this._state1L = t1L;
 
-		const sumL = (t1L >>> 0) + (s0L >>> 0);
-		t2U = (t1U + s0U + ((sumL / 2) >>> 31)) >>> 0;
-		t2L = sumL >>> 0;
-
-		return [t2U, t2L];
+		return [resU, resL];
 	}
 
 	random(): number {
 		const t2 = this.randomInt();
-		return (t2[0] * 4294967296 + t2[1]) / 18446744073709551616;
+		// Math.pow(2, -32) = 2.3283064365386963e-10
+		// Math.pow(2, -52) = 2.220446049250313e-16
+		return t2[0] * 2.3283064365386963e-10 + (t2[1] >>> 12) * 2.220446049250313e-16;
 	}
 
 	nextInt(min: number, sup: number): number {
@@ -105,12 +98,30 @@ export class Xorshift {
 			_state1L: this._state1L
 		};
 	}
+
+	// シード値が1つの場合にどのようにして初期状態を定義するかは特に定まっていない
+	// このコードはロジック的な裏付けは無いが採用例が多いために採用した
+	// 以下採用例
+	// http://meme.biology.tohoku.ac.jp/klabo-wiki/index.php?cmd=read&page=%B7%D7%BB%BB%B5%A1%2FC%2B%2B#y919a7e1
+	// http://hexadrive.sblo.jp/article/63660775.html
+	// http://meme.biology.tohoku.ac.jp/students/iwasaki/cxx/random.html#xorshift
+	private generateSeeds(seed: number): [number, number, number, number] {
+		const factor = 1812433253;
+		seed = factor * (seed ^ (seed >> 30)) + 1;
+		const seed1 = seed;
+		seed = factor * (seed ^ (seed >> 30)) + 2;
+		const seed2 = seed;
+		seed = factor * (seed ^ (seed >> 30)) + 3;
+		const seed3 = seed;
+		seed = factor * (seed ^ (seed >> 30)) + 4;
+		const seed4 = seed;
+		return [seed1, seed2, seed3, seed4];
+	}
 }
 
 /**
  * serialize/deserialize用のインターフェース
  */
-
 export interface XorshiftSerialization {
 	/**
 	 * @ignore

src/Xorshift.ts

@@ -1,7 +1,7 @@
 import { Xorshift } from "..";
 import { customMatchers } from "./helpers";
-/* eslint-disable-next-line @typescript-eslint/naming-convention, @typescript-eslint/no-var-requires */
-const RefXorshift = require("xorshift").constructor; // require と変数名でエラーとなるが、型定義がないのでコメントで無効とする。
+// eslint-disable-next-line @typescript-eslint/naming-convention, @typescript-eslint/no-var-requires
+const RefXorshift = require("xorshift").constructor;
 
 expect.extend(customMatchers);