static function numBitsDiffering($a, $b)
{
$a ^= $b;
// a now has a 1 bit exactly where its bit differs with b's
// Count bits set quickly with a series of lookups:
return self::$BITS_SET_IN_HALF_BYTE[$a & 0xf] + self::$BITS_SET_IN_HALF_BYTE[intval(uRShift($a, 4) & 0xf)] + self::$BITS_SET_IN_HALF_BYTE[uRShift($a, 8) & 0xf] + self::$BITS_SET_IN_HALF_BYTE[uRShift($a, 12) & 0xf] + self::$BITS_SET_IN_HALF_BYTE[uRShift($a, 16) & 0xf] + self::$BITS_SET_IN_HALF_BYTE[uRShift($a, 20) & 0xf] + self::$BITS_SET_IN_HALF_BYTE[uRShift($a, 24) & 0xf] + self::$BITS_SET_IN_HALF_BYTE[uRShift($a, 28) & 0xf];
}
/**
* <p>Gets the requested bit, where true means black.</p>
*
* @param $x; The horizontal component (i.e. which column)
* @param $y; The vertical component (i.e. which row)
* @return value of given bit in matrix
*/
public function get($x, $y)
{
$offset = intval($y * $this->rowSize + $x / 32);
if (!isset($this->bits[$offset])) {
$this->bits[$offset] = 0;
}
// return (($this->bits[$offset] >> ($x & 0x1f)) & 1) != 0;
return (uRShift($this->bits[$offset], $x & 0x1f) & 1) != 0;
//было >>> вместо >>, не знаю как эмулировать беззнаковый сдвиг
}
