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<?php
namespace Bitrix\Main\Type;
/**
* Class for generating pseudo random sequences.
* Never use it for any security or cryptographic purposes.
*
* <code>
* use \Bitrix\Main\Type\RandomSequence;
* $rs = new RandomSequence("A");
* echo $rs->randString();
* </code>
*/
class RandomSequence
{
private $mz = 0;
private $mw = 0;
/**
* Starts new sequence of pseudo random values.
*
* @param string $seed
* @return void
*/
public function __construct($seed = "")
{
$md = md5($seed);
$this->mz = crc32(substr($md, 0, 16));
$this->mw = crc32(substr($md, -16));
}
/**
* Returns next pseudo random value from the sequence.
* The result is signed 32 bit integer.
*
* @return int
*/
public function getNext()
{
$this->mz = 36969 * ($this->mz & 65535) + ($this->mz >> 16);
if($this->mz > 0x7FFFFFFF)
$this->mz = -(0xFFFFFFFF - $this->mz + 1);
$this->mw = 18000 * ($this->mw & 65535) + ($this->mw >> 16);
if($this->mw > 0x7FFFFFFF)
$this->mw = -(0xFFFFFFFF - $this->mw + 1);
//return ($this->mz << 16) + $this->mw;
$r = ($this->mz << 16) & 0xFFFF0000;
if($r > 0x7FFFFFFF)
$r = -(0xFFFFFFFF - $r + 1);
$r += $this->mw;
if($r > 0x7FFFFFFF)
$r = -(0xFFFFFFFF - $r + 1);
return ($r & 0xFFFFFFFF);
}
/**
* Returns next pseudo random number value from the sequence.
* between $min and $max including borders.
*
* @param int $min
* @param int $max
* @return int
* @throws \Bitrix\Main\NotSupportedException
*/
public function rand($min, $max)
{
if ($min >= $max)
throw new \Bitrix\Main\NotSupportedException("max parameter must be greater than min.");
$r = sprintf("%u", $this->getNext()) / sprintf("%u", 0xffffffff);
return intval($min + $r * ($max - $min + 1));
}
/**
* Returns next pseudo random string value from the sequence.
*
* @param int $length
* @return string
*/
public function randString($length = 10)
{
static $allChars = "abcdefghijklnmopqrstuvwxyzABCDEFGHIJKLNMOPQRSTUVWXYZ0123456789";
$result = "";
for ($i = 0; $i < $length; $i++)
{
$result .= $allChars[$this->rand(0, 61)];
}
return $result;
}
}