104     private static function checkInstance(self $x, self $y)  argument
106         if ($x->instanceID != $y->instanceID) {
167     private static function polynomialDivide($x, $y)  argument
173         $d = static::deg($y);
182             $s = static::polynomialMultiply($s, $y);
197     private static function regularPolynomialMultiply($x, $y)  argument
201         $y = strrev(BinaryField::base256ToBase2($y));
202         if (strlen($x) == strlen($y)) {
205             $length = max(strlen($x), strlen($y));
207             $y = str_pad($y, $length, '0');
218         for ($i = 0; $i < strlen($y); $i++) {
219             if ($y[$i] == '1') {
236     private static function polynomialMultiply($x, $y)  argument
238         if (strlen($x) == strlen($y)) {
241             $length = max(strlen($x), strlen($y));
243             $y = str_pad($y, $length, "\0", STR_PAD_LEFT);
249 …        self::subMultiply(str_pad($x, 4, "\0", STR_PAD_LEFT), str_pad($y, 4, "\0", STR_PAD_LEFT)) :
250                     self::subMultiply($x, $y);
252                 return self::regularPolynomialMultiply($x, $y);
259         $y1 = substr($y, 0, -$m);
260         $y0 = substr($y, -$m);
285      * @param string $y
289     private static function subMultiply($x, $y)  argument
292         $y = unpack('N', $y)[1];
299         $y0 = $y & 0x11111111;
300         $y1 = $y & 0x22222222;
301         $y2 = $y & 0x44444444;
302         $y3 = $y & 0x88888888;
323      * @param string $y
326     private static function subAdd2($x, $y)  argument
328         $length = max(strlen($x), strlen($y));
330         $y = str_pad($y, $length, "\0", STR_PAD_LEFT);
331         return $x ^ $y;
338      * @param string $y
341     private static function subAdd3($x, $y, $z)  argument
343         $length = max(strlen($x), strlen($y), strlen($z));
345         $y = str_pad($y, $length, "\0", STR_PAD_LEFT);
347         return $x ^ $y ^ $z;
355     public function add(self $y)  argument
357         static::checkInstance($this, $y);
362         $y = str_pad($y->value, $length, "\0", STR_PAD_LEFT);
364         return new static($this->instanceID, $x ^ $y);
382     public function multiply(self $y)  argument
384         static::checkInstance($this, $y);
386         return new static($this->instanceID, static::polynomialMultiply($this->value, $y->value));