可播种的随机数生成器 xoshiro128**

xoshiro128ss.js

/**
 * Random number generator "xoshiro128**".
 * @see http://prng.di.unimi.it/xoshiro128starstar.c
 */
class Xoshiro128ss {
    /**
     * Init the RNG with given seed.
     * The default seed is taken from current timestamp.
     * @param {Number} [a]
     * @param {Number} [b]
     * @param {Number} [c]
     * @param {Number} [d]
     */
    constructor(a, b, c, d) {
        a = a || (0x67452301 ^ Date.now());
        b = b || (0xEFCDAB89 ^ a);
        c = c || (0x98BADCFE ^ b);
        d = d || (0x10325476 ^ c)
        this.$ = new Uint32Array([a, b, c, d]);
    }
    /**
     * Get a random Uint32 number.
     * @returns {Number}
     */
    randInt() {
        const s = this.$;
        const t = s[1] << 9;
        const r = s[1] * 5;
        s[2] ^= s[0];
        s[3] ^= s[1];
        s[1] ^= s[2];
        s[0] ^= s[3];
        s[2] ^= t;
        s[3] = s[3] << 11 | s[3] >>> 21;
        return (r << 7 | r >>> 25) * 9 >>> 0;
    }
    /**
     * Get a random float number between 0 and 1.
     * @returns {Number}
     */
    randFloat() {
        return this.randInt() / 0xFFFFFFFF;
    }
}