Simple implementation of MT19937

MT19937.php

<?php

class MT19937 {
    protected $state = [];
    protected $index = 624;

    public function __construct($seed = null) {
        $this->state[0] = ($seed === null ? 5489 : $seed);
        for ($i = 1; $i < 624; $i++) {
            $this->state[$i] = (0x6C078965 * ($this->state[$i - 1] ^ ($this->state[$i - 1] >> 30)) + $i) & 0xffffffff;
        }
    }

    public function int32() {
        if ($this->index == 624) {
            $this->index = 0;
            for ($i = 0; $i < 227; $i++) {
                $y = ($this->state[$i] & 0x80000000) | ($this->state[$i + 1] & 0x7fffffff);
                $this->state[$i] = $this->state[$i + 397] ^ (($y >> 1) & 0x7fffffff) ^ (0x9908b0df * ($y & 1));
            }
            for (; $i < 623; $i++) {
                $y = ($this->state[$i] & 0x80000000) | ($this->state[$i + 1] & 0x7fffffff);
                $this->state[$i] = $this->state[$i - 227] ^ (($y >> 1) & 0x7fffffff) ^ (0x9908b0df * ($y & 1));
            }
            $y = ($this->state[623] & 0x80000000) | ($this->state[0] & 0x7fffffff);
            $this->state[623] = $this->state[396] ^ (($y >> 1) & 0x7fffffff) ^ (0x9908b0df * ($y & 1));
        }
        $y = $this->state[$this->index++];
        $y ^= ($y >> 11) & 0x001fffff;
        $y ^= ($y << 7) & 0x9d2c5680;
        $y ^= ($y << 15) & 0xefc60000;
        $y ^= ($y >> 18) & 0x00003fff;
        return $y;
    }

    public function int16() {
        return $this->int32() & 0xFFFF;
    }

    public function int8() {
        return $this->int32() & 0xFF;
    }
}