leo-mind-map/src/utils/mersenneTwister.js

一个简单的web在线思维导图

/**
 * @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：
 *
 * @param {*} seed
 */

export default function MersenneTwister(seed) {
  this.N = 624
  this.M = 397
  this.MATRIX_A = 0x9908b0df
  this.UPPER_MASK = 0x80000000
  this.LOWER_MASK = 0x7fffffff

  this.mt = new Array(this.N)
  this.mti = this.N + 1

  this.init_genrand(seed)
}

MersenneTwister.prototype.init_genrand = function (s) {
  this.mt[0] = s >>> 0
  for (this.mti = 1; this.mti < this.N; this.mti++) {
    s = this.mt[this.mti - 1] ^ (this.mt[this.mti - 1] >>> 30)
    this.mt[this.mti] =
      ((((s & 0xffff0000) >>> 16) * 1812433253) << 16) +
      (s & 0x0000ffff) * 1812433253 +
      this.mti
    this.mt[this.mti] >>>= 0
  }
}

MersenneTwister.prototype.genrand_int32 = function () {
  var y
  var mag01 = new Array(0x0, this.MATRIX_A)

  if (this.mti >= this.N) {
    var kk

    if (this.mti == this.N + 1) this.init_genrand(5489)

    for (kk = 0; kk < this.N - this.M; kk++) {
      y = (this.mt[kk] & this.UPPER_MASK) | (this.mt[kk + 1] & this.LOWER_MASK)
      this.mt[kk] = this.mt[kk + this.M] ^ (y >>> 1) ^ mag01[y & 0x1]
    }

    for (; kk < this.N - 1; kk++) {
      y = (this.mt[kk] & this.UPPER_MASK) | (this.mt[kk + 1] & this.LOWER_MASK)
      this.mt[kk] = this.mt[kk + (this.M - this.N)] ^ (y >>> 1) ^ mag01[y & 0x1]
    }

    y = (this.mt[this.N - 1] & this.UPPER_MASK) | (this.mt[0] & this.LOWER_MASK)
    this.mt[this.N - 1] = this.mt[this.M - 1] ^ (y >>> 1) ^ mag01[y & 0x1]

    this.mti = 0
  }

  y = this.mt[this.mti++]

  y ^= y >>> 11
  y ^= (y << 7) & 0x9d2c5680
  y ^= (y << 15) & 0xefc60000
  y ^= y >>> 18

  return y >>> 0
}