49 lines
1.2 KiB
TypeScript
49 lines
1.2 KiB
TypeScript
export const randomString = (length = 12) =>
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Math.random()
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.toString(16)
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.substring(2, length + 2)
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export function genHash(str: string) {
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// xmur3
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let h: number
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for (let i = 0, h = 1779033703 ^ str.length; i < str.length; i++) {
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h = Math.imul(h ^ str.charCodeAt(i), 3432918353)
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h = (h << 13) | (h >>> 19)
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}
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return function () {
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h = Math.imul(h ^ (h >>> 16), 2246822507)
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h = Math.imul(h ^ (h >>> 13), 3266489909)
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return (h ^= h >>> 16) >>> 0
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}
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}
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export function createRNG(seed: string) {
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// https://stackoverflow.com/a/47593316/1592933
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const gen = genHash(seed)
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let [a, b, c, d] = [gen(), gen(), gen(), gen()]
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// sfc32
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return function () {
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a >>>= 0
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b >>>= 0
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c >>>= 0
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d >>>= 0
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let t = (a + b) | 0
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a = b ^ (b >>> 9)
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b = (c + (c << 3)) | 0
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c = (c << 21) | (c >>> 11)
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d = (d + 1) | 0
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t = (t + d) | 0
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c = (c + t) | 0
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return (t >>> 0) / 4294967296
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}
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}
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export const shuffle = (array: unknown[], rand: () => number) => {
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for (let i = 0; i < array.length; i++) {
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const swapIndex = Math.floor(rand() * (array.length - i))
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;[array[i], array[swapIndex]] = [array[swapIndex], array[i]]
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}
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}
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