public function testNumberOfTrailingZeros()
{
$this->assertEquals(32, BitUtils::numberOfTrailingZeros(0));
$this->assertEquals(1, BitUtils::numberOfTrailingZeros(10));
$this->assertEquals(0, BitUtils::numberOfTrailingZeros(15));
$this->assertEquals(2, BitUtils::numberOfTrailingZeros(20));
}
/**
* Returns the mask bit for "getMaskPattern" at "x" and "y".
*
* See 8.8 of JISX0510:2004 for mask pattern conditions.
*
* @param integer $maskPattern
* @param integer $x
* @param integer $y
* @return integer
* @throws Exception\InvalidArgumentException
*/
public static function getDataMaskBit($maskPattern, $x, $y)
{
switch ($maskPattern) {
case 0:
$intermediate = $y + $x & 0x1;
break;
case 1:
$intermediate = $y & 0x1;
break;
case 2:
$intermediate = $x % 3;
break;
case 3:
$intermediate = ($y + $x) % 3;
break;
case 4:
$intermediate = BitUtils::unsignedRightShift($y, 1) + $x / 3 & 0x1;
break;
case 5:
$temp = $y * $x;
$intermediate = ($temp & 0x1) + $temp % 3;
break;
case 6:
$temp = $y * $x;
$intermediate = ($temp & 0x1) + $temp % 3 & 0x1;
break;
case 7:
$temp = $y * $x;
$intermediate = $temp % 3 + ($y + $x & 0x1) & 0x1;
break;
default:
throw new Exception\InvalidArgumentException('Invalid mask pattern: ' . $maskPattern);
}
return $intermediate === 0;
}
/**
* Gets the most bottom right set bit.
*
* This is useful in detecting a corner of a 'pure' barcode.
*
* @return SplFixedArray
*/
public function getBottomRightOnBit()
{
$bitsOffset = count($this->bits) - 1;
while ($bitsOffset >= 0 && $this->bits[$bitsOffset] === 0) {
$bitsOffset--;
}
if ($bitsOffset < 0) {
return null;
}
$x = intval($bitsOffset / $this->rowSize);
$y = $bitsOffset % $this->rowSize << 5;
$bits = $this->bits[$bitsOffset];
$bit = 0;
while (BitUtils::unsignedRightShift($bits, $bit) === 0) {
$bit--;
}
$x += $bit;
return SplFixedArray::fromArray(array($x, $y), false);
}
/**
* Gets the next unset bit position from a given position.
*
* @param integer $from
* @return integer
*/
public function getNextUnset($from)
{
if ($from >= $this->size) {
return $this->size;
}
$bitsOffset = $from >> 5;
$currentBits = ~$this->bits[$bitsOffset];
$bitsLength = count($this->bits);
$currentBits &= ~((1 << ($from & 0x1f)) - 1);
while ($currentBits === 0) {
if (++$bitsOffset === $bitsLength) {
return $this->size;
}
$currentBits = ~$this->bits[$bitsOffset];
}
$result = ($bitsOffset << 5) + BitUtils::numberOfTrailingZeros($currentBits);
return $result > $this->size ? $this->size : $result;
}
