Current File : /home/graphicd/public_html/vebto/vendor/google/crc32/src/Table.php
<?php
/**
* Copyright 2019 Google LLC
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
namespace Google\CRC32;
final class Table
{
private static $tables = array();
/**
* Echos the given table. Useful for building a static table to include in source code.
*
* @param array $table The table
*/
public static function output(array $table)
{
foreach ($table as $i => $value) {
echo "0x" . int2hex($value) . ",";
if ($i % 4 == 3) {
echo "\n";
} else {
echo " ";
}
}
echo "\n\n";
}
/**
* Gets a CRC table, by creating it, or using a previously cached result.
*
* @param integer $polynomial The polynomial
*
* @return array The table
*/
public static function get($polynomial)
{
if (isset(self::$tables[$polynomial])) {
return self::$tables[$polynomial];
}
self::$tables[$polynomial] = self::create($polynomial);
return self::$tables[$polynomial];
}
/**
* Create a CRC table.
*
* @param integer $polynomial The polynomial.
*
* @return array The table.
*/
public static function create($polynomial)
{
$table = array_fill(0, 256, 0);
for ($i = 0; $i < 256; $i++) {
$crc = $i;
for ($j = 0; $j < 8; $j++) {
if ($crc & 1 == 1) {
$crc = ($crc >> 1) ^ $polynomial;
} else {
$crc >>= 1;
}
}
$table[$i] = $crc;
}
return $table;
}
/**
* Create a CRC table sliced by 4.
*
* @param integer $polynomial The polynomial.
*
* @return array The table.
*/
public static function create4($polynomial)
{
$table = array_fill(0, 4, array_fill(0, 256, 0));
$table[0] = self::create($polynomial);
for ($i = 0; $i < 256; $i++) {
// for Slicing-by-4 and Slicing-by-8
$table[1][$i] = ($table[0][$i] >> 8) ^ $table[0][$table[0][$i] & 0xFF];
$table[2][$i] = ($table[1][$i] >> 8) ^ $table[0][$table[1][$i] & 0xFF];
$table[3][$i] = ($table[2][$i] >> 8) ^ $table[0][$table[2][$i] & 0xFF];
/*
// only Slicing-by-8
$table[4][$i] = ($table[3][$i] >> 8) ^ $table[0][$table[3][$i] & 0xFF];
$table[5][$i] = ($table[4][$i] >> 8) ^ $table[0][$table[4][$i] & 0xFF];
$table[6][$i] = ($table[5][$i] >> 8) ^ $table[0][$table[5][$i] & 0xFF];
$table[7][$i] = ($table[6][$i] >> 8) ^ $table[0][$table[6][$i] & 0xFF];
*/
}
return $table;
}
}
Mini Shell