<?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;
use Google\CRC32\CRC32;
use Google\CRC32\CRCInterface;
/**
* A CRC32 implementation based on the PHP hash functions.
*/
final class Builtin implements CRCInterface
{
private $hc;
private static $mapping = [
CRC32::IEEE => 'crc32b',
CRC32::CASTAGNOLI => 'crc32c',
];
/**
* Returns true if this $polynomial is supported by the builtin PHP hash function.
*
* @param integer $polynomial The polynomial
*
* @return boolean
*/
public static function supports($polynomial)
{
if (!isset(self::$mapping[$polynomial])) {
return false;
}
$algo = self::$mapping[$polynomial];
return in_array($algo, hash_algos());
}
public function __construct($polynomial)
{
if (!self::supports($polynomial)) {
throw new \InvalidArgumentException("hash_algos() does not list this polynomial.");
}
$this->algo = self::$mapping[$polynomial];
$this->reset();
}
public function reset()
{
$this->hc = hash_init($this->algo);
}
public function update($data)
{
hash_update($this->hc, $data);
}
public function hash($raw_output = null)
{
// hash_final will destory the Hash Context resource, so operate on a copy.
$hc = hash_copy($this->hc);
return hash_final($hc, $raw_output);
}
public function version()
{
return $this->algo . ' PHP HASH';
}
public function __clone()
{
$this->hc = hash_copy($this->hc);
}
}