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const N = 624;
const M = 397;
const MATRIX_A = 0x9908b0df;
const UPPER_MASK = 0x80000000;
const LOWER_MASK = 0x7fffffff;
const mag01 = [ 0x0, MATRIX_A ];
const INIT_MUL = 1812433253;
/// The given function generates random numbers on the [ 0, 0xffffffff ]-interval.
export const makeRandom = (seed = (new Date()).getTime()) => {
const mt = new Array(N);
let mti = null;
mt[0] = seed >>> 0;
for (mti = 1; mti < N; mti++) {
const s0 = mt[mti - 1] ^ (mt[mti - 1] >>> 30);
mt[mti] =
(((((s0 & 0xffff0000) >>> 16) * INIT_MUL) << 16) +
(( s0 & 0x0000ffff) * INIT_MUL) +
mti) >>> 0;
}
return () => {
if (mti >= N) {
let kk = null;
for (kk = 0; kk < N - M; kk++) {
const y0 =
(mt[kk] & UPPER_MASK) |
(mt[kk + 1] & LOWER_MASK);
mt[kk] = mt[kk + M] ^ (y0 >>> 1) ^ mag01[y0 & 0x1];
}
for (; kk < N - 1; kk++) {
const y1 =
(mt[kk] & UPPER_MASK) |
(mt[kk + 1] & LOWER_MASK);
mt[kk] = mt[kk + (M - N)] ^ (y1 >>> 1) ^ mag01[y1 & 0x1];
}
const y2 =
(mt[N - 1] & UPPER_MASK) |
(mt[0] & LOWER_MASK);
mt[N - 1] = mt[M - 1] ^ (y2 >>> 1) ^ mag01[y2 & 0x1];
mti = 0;
}
let y = mt[mti++];
y ^= (y >>> 11);
y ^= (y << 7) & 0x9d2c5680;
y ^= (y << 15) & 0xefc60000;
y ^= (y >>> 18);
return y >>> 0;
};
};
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