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<?php |
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/** |
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* Class ReedSolomonEncoder |
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* |
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* @created 07.01.2021 |
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* @author smiley <[email protected]> |
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* @copyright 2021 smiley |
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* @license MIT |
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*/ |
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namespace chillerlan\QRCode\Common; |
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use function array_fill, array_merge, count, max; |
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/** |
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* ISO/IEC 18004:2000 Section 8.5 ff |
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* |
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* @see http://www.thonky.com/qr-code-tutorial/error-correction-coding |
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*/ |
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final class ReedSolomonEncoder{ |
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private Version $version; |
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private EccLevel $eccLevel; |
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private array $interleavedData; |
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private int $interleavedDataIndex; |
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/** |
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* ReedSolomonDecoder constructor |
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*/ |
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public function __construct(Version $version, EccLevel $eccLevel){ |
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$this->version = $version; |
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$this->eccLevel = $eccLevel; |
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} |
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/** |
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* ECC interleaving |
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* |
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* @throws \chillerlan\QRCode\QRCodeException |
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*/ |
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public function interleaveEcBytes(BitBuffer $bitBuffer):array{ |
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[$numEccCodewords, [[$l1, $b1], [$l2, $b2]]] = $this->version->getRSBlocks($this->eccLevel); |
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$rsBlocks = array_fill(0, $l1, [$numEccCodewords + $b1, $b1]); |
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if($l2 > 0){ |
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$rsBlocks = array_merge($rsBlocks, array_fill(0, $l2, [$numEccCodewords + $b2, $b2])); |
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} |
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$bitBufferData = $bitBuffer->getBuffer(); |
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$dataBytes = []; |
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$ecBytes = []; |
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$maxDataBytes = 0; |
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$maxEcBytes = 0; |
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$dataByteOffset = 0; |
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foreach($rsBlocks as $key => $block){ |
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[$rsBlockTotal, $dataByteCount] = $block; |
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$dataBytes[$key] = []; |
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for($i = 0; $i < $dataByteCount; $i++){ |
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$dataBytes[$key][$i] = $bitBufferData[$i + $dataByteOffset] & 0xff; |
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} |
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$ecByteCount = $rsBlockTotal - $dataByteCount; |
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$ecBytes[$key] = $this->encode($dataBytes[$key], $ecByteCount); |
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$maxDataBytes = max($maxDataBytes, $dataByteCount); |
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$maxEcBytes = max($maxEcBytes, $ecByteCount); |
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$dataByteOffset += $dataByteCount; |
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} |
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$this->interleavedData = array_fill(0, $this->version->getTotalCodewords(), 0); |
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$this->interleavedDataIndex = 0; |
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$numRsBlocks = $l1 + $l2; |
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$this->interleave($dataBytes, $maxDataBytes, $numRsBlocks); |
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$this->interleave($ecBytes, $maxEcBytes, $numRsBlocks); |
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return $this->interleavedData; |
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} |
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/** |
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* |
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*/ |
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private function encode(array $dataBytes, int $ecByteCount):array{ |
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$rsPoly = new GenericGFPoly([1]); |
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for($i = 0; $i < $ecByteCount; $i++){ |
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$rsPoly = $rsPoly->multiply(new GenericGFPoly([1, GF256::exp($i)])); |
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} |
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$rsPolyDegree = $rsPoly->getDegree(); |
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$modCoefficients = (new GenericGFPoly($dataBytes, $rsPolyDegree)) |
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->mod($rsPoly) |
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->getCoefficients() |
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; |
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$ecBytes = array_fill(0, $rsPolyDegree, 0); |
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$count = count($modCoefficients) - $rsPolyDegree; |
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foreach($ecBytes as $i => &$val){ |
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$modIndex = $i + $count; |
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$val = $modIndex >= 0 ? $modCoefficients[$modIndex] : 0; |
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} |
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return $ecBytes; |
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} |
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/** |
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* |
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*/ |
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private function interleave(array $byteArray, int $maxBytes, int $numRsBlocks):void{ |
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for($x = 0; $x < $maxBytes; $x++){ |
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for($y = 0; $y < $numRsBlocks; $y++){ |
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if($x < count($byteArray[$y])){ |
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$this->interleavedData[$this->interleavedDataIndex++] = $byteArray[$y][$x]; |
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} |
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} |
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} |
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} |
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} |
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chillerlan /
php-qrcode
