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66 lines
1.8 KiB
JavaScript
66 lines
1.8 KiB
JavaScript
/**
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* @description 为了保证相同的内容每次生成的随机数都是一样的，我们可以使用一个伪随机数生成器（PRNG），并使用内容的哈希值作为种子。以下是一个使用Mersenne Twister算法的PRNG的实现：
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*
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* @param {*} seed
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*/
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export default function MersenneTwister(seed) {
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this.N = 624
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this.M = 397
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this.MATRIX_A = 0x9908b0df
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this.UPPER_MASK = 0x80000000
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this.LOWER_MASK = 0x7fffffff
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this.mt = new Array(this.N)
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this.mti = this.N + 1
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this.init_genrand(seed)
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}
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MersenneTwister.prototype.init_genrand = function (s) {
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this.mt[0] = s >>> 0
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for (this.mti = 1; this.mti < this.N; this.mti++) {
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s = this.mt[this.mti - 1] ^ (this.mt[this.mti - 1] >>> 30)
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this.mt[this.mti] =
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((((s & 0xffff0000) >>> 16) * 1812433253) << 16) +
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(s & 0x0000ffff) * 1812433253 +
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this.mti
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this.mt[this.mti] >>>= 0
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}
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}
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MersenneTwister.prototype.genrand_int32 = function () {
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var y
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var mag01 = new Array(0x0, this.MATRIX_A)
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if (this.mti >= this.N) {
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var kk
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if (this.mti == this.N + 1) this.init_genrand(5489)
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for (kk = 0; kk < this.N - this.M; kk++) {
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y = (this.mt[kk] & this.UPPER_MASK) | (this.mt[kk + 1] & this.LOWER_MASK)
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this.mt[kk] = this.mt[kk + this.M] ^ (y >>> 1) ^ mag01[y & 0x1]
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}
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for (; kk < this.N - 1; kk++) {
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y = (this.mt[kk] & this.UPPER_MASK) | (this.mt[kk + 1] & this.LOWER_MASK)
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this.mt[kk] = this.mt[kk + (this.M - this.N)] ^ (y >>> 1) ^ mag01[y & 0x1]
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}
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y = (this.mt[this.N - 1] & this.UPPER_MASK) | (this.mt[0] & this.LOWER_MASK)
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this.mt[this.N - 1] = this.mt[this.M - 1] ^ (y >>> 1) ^ mag01[y & 0x1]
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this.mti = 0
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}
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y = this.mt[this.mti++]
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y ^= y >>> 11
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y ^= (y << 7) & 0x9d2c5680
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y ^= (y << 15) & 0xefc60000
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y ^= y >>> 18
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return y >>> 0
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}
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