lib0/prng/Xorshift32.js

/**
 * @module prng
 */

import * as binary from '../binary.js'

/**
 * Xorshift32 is a very simple but elegang PRNG with a period of `2^32-1`.
 */
export class Xorshift32 {
  /**
   * @param {number} seed Unsigned 32 bit number
   */
  constructor (seed) {
    this.seed = seed
    /**
     * @type {number}
     */
    this._state = seed
  }

  /**
   * Generate a random signed integer.
   *
   * @return {Number} A 32 bit signed integer.
   */
  next () {
    let x = this._state
    x ^= x << 13
    x ^= x >> 17
    x ^= x << 5
    this._state = x
    return (x >>> 0) / (binary.BITS32 + 1)
  }
}