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# PHP Decode

``````<?php
/*
*
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
*
* Unless required by applicable law or agreed to in writing, software
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
*/

namespace Zxing\Common\Reedsolomon;

/**
* <p>This class contains utility methods for performing mathematical operations over
* the Galois Fields. Operations use a given primitive polynomial in calculations.</p>
*
* <p>Throughout this package, elements of the GF are represented as an {@code int}
* for convenience and speed (but at the cost of memory).
* </p>
*
* @author Sean Owen
* @author David Olivier
*/
final class GenericGF
{
public static \$AZTEC_DATA_12;
public static \$AZTEC_DATA_10;
public static \$AZTEC_DATA_6;
public static \$AZTEC_PARAM;
public static \$QR_CODE_FIELD_256;
public static \$DATA_MATRIX_FIELD_256;
public static \$AZTEC_DATA_8;
public static \$MAXICODE_FIELD_64;

private array \$expTable = [];
private array \$logTable = [];

/**
* Create a representation of GF(size) using the given primitive polynomial.
*
* @param int \$primitive irreducible polynomial whose coefficients are represented by
*                  the bits of an int, where the least-significant bit represents the constant
*                  coefficient
* @param int \$size      the size of the field
* @param int \$generatorBase the factor b in the generator polynomial can be 0- or 1-based
(g(x) = (x+a^b)(x+a^(b+1))...(x+a^(b+2t-1))).
In most cases it should be 1, but for QR code it is 0.
*/
public function __construct(private \$primitive, private \$size, private \$generatorBase)
{
\$x = 1;
for (\$i = 0; \$i < \$size; \$i++) {
\$this->expTable[\$i] = \$x;
\$x *= 2; // we're assuming the generator alpha is 2
if (\$x >= \$size) {
\$x ^= \$primitive;
\$x &= \$size - 1;
}
}
for (\$i = 0; \$i < \$size - 1; \$i++) {
\$this->logTable[\$this->expTable[\$i]] = \$i;
}
// logTable[0] == 0 but this should never be used
\$this->zero = new GenericGFPoly(\$this, [0]);
\$this->one = new GenericGFPoly(\$this, [1]);
}

public static function Init(): void
{
self::\$AZTEC_DATA_12 = new GenericGF(0x1069, 4096, 1); // x^12 + x^6 + x^5 + x^3 + 1
self::\$AZTEC_DATA_10 = new GenericGF(0x409, 1024, 1); // x^10 + x^3 + 1
self::\$AZTEC_DATA_6 = new GenericGF(0x43, 64, 1); // x^6 + x + 1
self::\$AZTEC_PARAM = new GenericGF(0x13, 16, 1); // x^4 + x + 1
self::\$QR_CODE_FIELD_256 = new GenericGF(0x011D, 256, 0); // x^8 + x^4 + x^3 + x^2 + 1
self::\$DATA_MATRIX_FIELD_256 = new GenericGF(0x012D, 256, 1); // x^8 + x^5 + x^3 + x^2 + 1
self::\$AZTEC_DATA_8 = self::\$DATA_MATRIX_FIELD_256;
self::\$MAXICODE_FIELD_64 = self::\$AZTEC_DATA_6;
}

/**
* Implements both addition and subtraction -- they are the same in GF(size).
*
* @return float|int sum/difference of a and b
*
* @param float|int|null \$b
*/
public static function addOrSubtract(int \$a, int|float|null \$b)
{
return \$a ^ \$b;
}

public function getZero(): GenericGFPoly
{
return \$this->zero;
}

public function getOne(): GenericGFPoly
{
return \$this->one;
}

/**
* @return GenericGFPoly  the monomial representing coefficient * x^degree
*/
public function buildMonomial(\$degree, int \$coefficient)
{
if (\$degree < 0) {
throw new \InvalidArgumentException();
}
if (\$coefficient == 0) {
return \$this->zero;
}
\$coefficients = fill_array(0, \$degree + 1, 0);//new int[degree + 1];
\$coefficients[0] = \$coefficient;

return new GenericGFPoly(\$this, \$coefficients);
}

/**
* @return 2 to the power of a in GF(size)
*/
public function exp(\$a)
{
return \$this->expTable[\$a];
}

/**
* @return float base 2 log of a in GF(size)
*/
public function log(float|int|null \$a)
{
if (\$a == 0) {
throw new \InvalidArgumentException();
}

return \$this->logTable[\$a];
}

/**
* @return float multiplicative inverse of a
*/
public function inverse(\$a)
{
if (\$a == 0) {
throw new \Exception();
}

return \$this->expTable[\$this->size - \$this->logTable[\$a] - 1];
}

/**
* @return int product of a and b in GF(size)
*
* @param float|int|null \$b
* @param float|int|null \$a
*/
public function multiply(int|float|null \$a, int|float|null \$b)
{
if (\$a == 0 || \$b == 0) {
return 0;
}

return \$this->expTable[(\$this->logTable[\$a] + \$this->logTable[\$b]) % (\$this->size - 1)];
}

public function getSize()
{
return \$this->size;
}

public function getGeneratorBase()
{
return \$this->generatorBase;
}

// @Override
public function toString(): string
{
return "GF(0x" . dechex((int)(\$this->primitive)) . ',' . \$this->size . ')';
}
}

GenericGF::Init();
?>``````

#### Original Code

``````<?php
/*
*
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
*
* Unless required by applicable law or agreed to in writing, software
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
*/

namespace Zxing\Common\Reedsolomon;

/**
* <p>This class contains utility methods for performing mathematical operations over
* the Galois Fields. Operations use a given primitive polynomial in calculations.</p>
*
* <p>Throughout this package, elements of the GF are represented as an {@code int}
* for convenience and speed (but at the cost of memory).
* </p>
*
* @author Sean Owen
* @author David Olivier
*/
final class GenericGF
{
public static \$AZTEC_DATA_12;
public static \$AZTEC_DATA_10;
public static \$AZTEC_DATA_6;
public static \$AZTEC_PARAM;
public static \$QR_CODE_FIELD_256;
public static \$DATA_MATRIX_FIELD_256;
public static \$AZTEC_DATA_8;
public static \$MAXICODE_FIELD_64;

private array \$expTable = [];
private array \$logTable = [];

/**
* Create a representation of GF(size) using the given primitive polynomial.
*
* @param int \$primitive irreducible polynomial whose coefficients are represented by
*                  the bits of an int, where the least-significant bit represents the constant
*                  coefficient
* @param int \$size      the size of the field
* @param int \$generatorBase the factor b in the generator polynomial can be 0- or 1-based
(g(x) = (x+a^b)(x+a^(b+1))...(x+a^(b+2t-1))).
In most cases it should be 1, but for QR code it is 0.
*/
public function __construct(private \$primitive, private \$size, private \$generatorBase)
{
\$x = 1;
for (\$i = 0; \$i < \$size; \$i++) {
\$this->expTable[\$i] = \$x;
\$x *= 2; // we're assuming the generator alpha is 2
if (\$x >= \$size) {
\$x ^= \$primitive;
\$x &= \$size - 1;
}
}
for (\$i = 0; \$i < \$size - 1; \$i++) {
\$this->logTable[\$this->expTable[\$i]] = \$i;
}
// logTable[0] == 0 but this should never be used
\$this->zero = new GenericGFPoly(\$this, [0]);
\$this->one = new GenericGFPoly(\$this, [1]);
}

public static function Init(): void
{
self::\$AZTEC_DATA_12 = new GenericGF(0x1069, 4096, 1); // x^12 + x^6 + x^5 + x^3 + 1
self::\$AZTEC_DATA_10 = new GenericGF(0x409, 1024, 1); // x^10 + x^3 + 1
self::\$AZTEC_DATA_6 = new GenericGF(0x43, 64, 1); // x^6 + x + 1
self::\$AZTEC_PARAM = new GenericGF(0x13, 16, 1); // x^4 + x + 1
self::\$QR_CODE_FIELD_256 = new GenericGF(0x011D, 256, 0); // x^8 + x^4 + x^3 + x^2 + 1
self::\$DATA_MATRIX_FIELD_256 = new GenericGF(0x012D, 256, 1); // x^8 + x^5 + x^3 + x^2 + 1
self::\$AZTEC_DATA_8 = self::\$DATA_MATRIX_FIELD_256;
self::\$MAXICODE_FIELD_64 = self::\$AZTEC_DATA_6;
}

/**
* Implements both addition and subtraction -- they are the same in GF(size).
*
* @return float|int sum/difference of a and b
*
* @param float|int|null \$b
*/
public static function addOrSubtract(int \$a, int|float|null \$b)
{
return \$a ^ \$b;
}

public function getZero(): GenericGFPoly
{
return \$this->zero;
}

public function getOne(): GenericGFPoly
{
return \$this->one;
}

/**
* @return GenericGFPoly  the monomial representing coefficient * x^degree
*/
public function buildMonomial(\$degree, int \$coefficient)
{
if (\$degree < 0) {
throw new \InvalidArgumentException();
}
if (\$coefficient == 0) {
return \$this->zero;
}
\$coefficients = fill_array(0, \$degree + 1, 0);//new int[degree + 1];
\$coefficients[0] = \$coefficient;

return new GenericGFPoly(\$this, \$coefficients);
}

/**
* @return 2 to the power of a in GF(size)
*/
public function exp(\$a)
{
return \$this->expTable[\$a];
}

/**
* @return float base 2 log of a in GF(size)
*/
public function log(float|int|null \$a)
{
if (\$a == 0) {
throw new \InvalidArgumentException();
}

return \$this->logTable[\$a];
}

/**
* @return float multiplicative inverse of a
*/
public function inverse(\$a)
{
if (\$a == 0) {
throw new \Exception();
}

return \$this->expTable[\$this->size - \$this->logTable[\$a] - 1];
}

/**
* @return int product of a and b in GF(size)
*
* @param float|int|null \$b
* @param float|int|null \$a
*/
public function multiply(int|float|null \$a, int|float|null \$b)
{
if (\$a == 0 || \$b == 0) {
return 0;
}

return \$this->expTable[(\$this->logTable[\$a] + \$this->logTable[\$b]) % (\$this->size - 1)];
}

public function getSize()
{
return \$this->size;
}

public function getGeneratorBase()
{
return \$this->generatorBase;
}

// @Override
public function toString(): string
{
return "GF(0x" . dechex((int)(\$this->primitive)) . ',' . \$this->size . ')';
}
}

GenericGF::Init();
``````

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#### Stats

 MD5 a39fbd297d746ad148d252b19969fb87 Eval Count 0 Decode Time 84 ms