Created
September 29, 2018 12:33
-
-
Save hightemp/4da5ac39b8d57fcd7e7988b90a48017d to your computer and use it in GitHub Desktop.
PHP crc64
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
<?php | |
/** | |
* @return array | |
*/ | |
function crc64Table() | |
{ | |
$crc64tab = []; | |
// ECMA polynomial | |
$poly64rev = (0xC96C5795 << 32) | 0xD7870F42; | |
// ISO polynomial | |
// $poly64rev = (0xD8 << 56); | |
for ($i = 0; $i < 256; $i++) | |
{ | |
for ($part = $i, $bit = 0; $bit < 8; $bit++) { | |
if ($part & 1) { | |
$part = (($part >> 1) & ~(0x8 << 60)) ^ $poly64rev; | |
} else { | |
$part = ($part >> 1) & ~(0x8 << 60); | |
} | |
} | |
$crc64tab[$i] = $part; | |
} | |
return $crc64tab; | |
} | |
/** | |
* @param string $string | |
* @param string $format | |
* @return mixed | |
* | |
* Formats: | |
* crc64('php'); // afe4e823e7cef190 | |
* crc64('php', '0x%x'); // 0xafe4e823e7cef190 | |
* crc64('php', '0x%X'); // 0xAFE4E823E7CEF190 | |
* crc64('php', '%d'); // -5772233581471534704 signed int | |
* crc64('php', '%u'); // 12674510492238016912 unsigned int | |
*/ | |
function crc64($string, $format = '%x') | |
{ | |
static $crc64tab; | |
if ($crc64tab === null) { | |
$crc64tab = crc64Table(); | |
} | |
$crc = 0; | |
for ($i = 0; $i < strlen($string); $i++) { | |
$crc = $crc64tab[($crc ^ ord($string[$i])) & 0xff] ^ (($crc >> 8) & ~(0xff << 56)); | |
} | |
return sprintf($format, $crc); | |
} |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment