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<?php |
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/** |
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* Class BitBuffer |
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* |
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* @created 25.11.2015 |
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* @author Smiley <[email protected]> |
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* @copyright 2015 Smiley |
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* @license MIT |
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*/ |
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namespace chillerlan\QRCode\Common; |
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use chillerlan\QRCode\QRCodeException; |
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use function count, floor, min; |
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/** |
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* Holds the raw binary data |
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*/ |
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final class BitBuffer{ |
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/** |
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* The buffer content |
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* |
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* @var int[] |
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*/ |
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private array $buffer; |
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/** |
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* Length of the content (bits) |
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*/ |
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private int $length; |
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/** |
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* Read count (bytes) |
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*/ |
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private int $bytesRead = 0; |
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/** |
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* Read count (bits) |
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*/ |
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private int $bitsRead = 0; |
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/** |
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* BitBuffer constructor. |
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* |
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* @param int[]|null $bytes |
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*/ |
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public function __construct(array $bytes = null){ |
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$this->buffer = $bytes ?? []; |
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$this->length = count($this->buffer); |
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} |
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/** |
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* appends a sequence of bits |
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*/ |
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public function put(int $bits, int $length):self{ |
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for($i = 0; $i < $length; $i++){ |
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$this->putBit((($bits >> ($length - $i - 1)) & 1) === 1); |
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} |
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return $this; |
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} |
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/** |
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* appends a single bit |
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*/ |
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public function putBit(bool $bit):self{ |
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$bufIndex = (int)floor($this->length / 8); |
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if(count($this->buffer) <= $bufIndex){ |
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$this->buffer[] = 0; |
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} |
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if($bit === true){ |
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$this->buffer[$bufIndex] |= (0x80 >> ($this->length % 8)); |
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} |
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$this->length++; |
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return $this; |
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} |
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/** |
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* returns the current buffer length |
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*/ |
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public function getLength():int{ |
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return $this->length; |
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} |
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/** |
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* returns the buffer content |
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*/ |
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public function getBuffer():array{ |
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return $this->buffer; |
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} |
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/** |
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* @return int number of bits that can be read successfully |
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*/ |
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public function available():int{ |
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return 8 * ($this->length - $this->bytesRead) - $this->bitsRead; |
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} |
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/** |
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* @author Sean Owen, ZXing |
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* |
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* @param int $numBits number of bits to read |
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* |
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* @return int representing the bits read. The bits will appear as the least-significant bits of the int |
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* @throws \chillerlan\QRCode\QRCodeException if numBits isn't in [1,32] or more than is available |
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*/ |
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public function read(int $numBits):int{ |
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if($numBits < 1 || $numBits > $this->available()){ |
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throw new QRCodeException('invalid $numBits: '.$numBits); |
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} |
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$result = 0; |
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// First, read remainder from current byte |
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if($this->bitsRead > 0){ |
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$bitsLeft = 8 - $this->bitsRead; |
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$toRead = min($numBits, $bitsLeft); |
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$bitsToNotRead = $bitsLeft - $toRead; |
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$mask = (0xff >> (8 - $toRead)) << $bitsToNotRead; |
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$result = ($this->buffer[$this->bytesRead] & $mask) >> $bitsToNotRead; |
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$numBits -= $toRead; |
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$this->bitsRead += $toRead; |
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if($this->bitsRead === 8){ |
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$this->bitsRead = 0; |
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$this->bytesRead++; |
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} |
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} |
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// Next read whole bytes |
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if($numBits > 0){ |
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while($numBits >= 8){ |
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$result = ($result << 8) | ($this->buffer[$this->bytesRead] & 0xff); |
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$this->bytesRead++; |
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$numBits -= 8; |
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} |
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// Finally read a partial byte |
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if($numBits > 0){ |
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$bitsToNotRead = 8 - $numBits; |
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$mask = (0xff >> $bitsToNotRead) << $bitsToNotRead; |
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$result = ($result << $numBits) | (($this->buffer[$this->bytesRead] & $mask) >> $bitsToNotRead); |
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$this->bitsRead += $numBits; |
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} |
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} |
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return $result; |
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} |
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/** |
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* Clears the buffer and resets the stats |
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*/ |
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public function clear():self{ |
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$this->buffer = []; |
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$this->length = 0; |
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return $this->rewind(); |
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} |
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/** |
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* Resets the read-counters |
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*/ |
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public function rewind():self{ |
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$this->bytesRead = 0; |
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$this->bitsRead = 0; |
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return $this; |
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} |
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} |
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chillerlan /
php-qrcode
