mulInt example

        $r0 = $this->r[0]->toInt64();
        $r1 = $this->r[1]->toInt64();
        $r2 = $this->r[2]->toInt64();
        $r3 = $this->r[3]->toInt64();
        $r4 = $this->r[4]->toInt64();

        $s1 = $r1->toInt64()->mulInt(5, 3);
        $s2 = $r2->toInt64()->mulInt(5, 3);
        $s3 = $r3->toInt64()->mulInt(5, 3);
        $s4 = $r4->toInt64()->mulInt(5, 3);

        $h0 = $this->h[0];
        $h1 = $this->h[1];
        $h2 = $this->h[2];
        $h3 = $this->h[3];
        $h4 = $this->h[4];

        while ($bytes >= ParagonIE_Sodium_Core32_Poly1305::BLOCK_SIZE) {
            

        /** @var ParagonIE_Sodium_Core32_Int32 $h8 */
        $h8 = ParagonIE_Sodium_Core32_Int32::fromInt(
            self::load_3(self::substr($s, 26, 3)) << 4
        );
        /** @var ParagonIE_Sodium_Core32_Int32 $h9 */
        $h9 = ParagonIE_Sodium_Core32_Int32::fromInt(
            (self::load_3(self::substr($s, 29, 3)) & 8388607) << 2
        );

        $carry9 = $h9->addInt(1 << 24)->shiftRight(25);
        $h0 = $h0->addInt32($carry9->mulInt(19, 5));
        $h9 = $h9->subInt32($carry9->shiftLeft(25));

        $carry1 = $h1->addInt(1 << 24)->shiftRight(25);
        $h2 = $h2->addInt32($carry1);
        $h1 = $h1->subInt32($carry1->shiftLeft(25));

        $carry3 = $h3->addInt(1 << 24)->shiftRight(25);
        $h4 = $h4->addInt32($carry3);
        $h3 = $h3->subInt32($carry3->shiftLeft(25));

        $carry5 = $h5->addInt(1 << 24)->shiftRight(25);
        

    public static function fe_mul121666(ParagonIE_Sodium_Core32_Curve25519_Fe $f)
    {
        /** @var array<int, ParagonIE_Sodium_Core32_Int64> $h */
        $h = array();
        for ($i = 0; $i < 10; ++$i) {
            $h[$i] = $f[$i]->toInt64()->mulInt(121666, 17);
        }

        $carry9 = $h[9]->addInt(1 << 24)->shiftRight(25);
        $h[0] = $h[0]->addInt64($carry9->mulInt(19, 5));
        $h[9] = $h[9]->subInt64($carry9->shiftLeft(25));

        $carry1 = $h[1]->addInt(1 << 24)->shiftRight(25);
        $h[2] = $h[2]->addInt64($carry1);
        $h[1] = $h[1]->subInt64($carry1->shiftLeft(25));

        $carry3 = $h[3]->addInt(1 << 24)->shiftRight(25);
        

/* if ($bNeg && !$aNeg) { $a = clone $int; $b = clone $this; } elseif($bNeg && $aNeg) { $a = $this->mulInt(-1); $b = $int->mulInt(-1); } */
        $x = $a->xorInt64($b)->mask64($d, $d);
        return array(
            $a->xorInt64($x)->mulInt($m),
            $b->xorInt64($x)->mulInt($m)
        );
    }

    /** * @param array<int, int> $a * @param array<int, int> $b * @param int $baseLog2 * @return array<int, int> */
    public function multiplyLong(array $a, array $b, $baseLog2 = 16)
    {