pagerank bulma scriptleri nasıl buluyorlar pagerank ı bakıyorum kodlara bir sürü gereksiz kod var

<?php
define('GOOGLE_MAGIC', 0xE6359A60);

function toInt32(& $x){ 
    $z = hexdec(80000000); 
    $y = (int)$x; 
     if($y==-$z&&$x<-$z){ 
         $y = (int)((-1)*$x); 
         $y = (-1)*$y; 
    } 
    $x = $y; 
}  

function zeroFill($a, $b)
{
    $z = hexdec(80000000);
        if ($z & $a)
        {
            $a = ($a>>1);
            $a &= (~$z);
            $a |= 0x40000000;
            $a = ($a>>($b-1));
        }
        else
        {
            $a = ($a>>$b);
        }
        return $a;
}

function mix($a,$b,$c) {
  $a -= $b; $a -= $c; toInt32($a); $a = (int)($a ^ (zeroFill($c,13))); 
  $b -= $c; $b -= $a; toInt32($b); $b = (int)($b ^ ($a<<8)); 
  $c -= $a; $c -= $b; toInt32($c); $c = (int)($c ^ (zeroFill($b,13))); 
  $a -= $b; $a -= $c; toInt32($a); $a = (int)($a ^ (zeroFill($c,12))); 
  $b -= $c; $b -= $a; toInt32($b); $b = (int)($b ^ ($a<<16)); 
  $c -= $a; $c -= $b; toInt32($c); $c = (int)($c ^ (zeroFill($b,5))); 
  $a -= $b; $a -= $c; toInt32($a); $a = (int)($a ^ (zeroFill($c,3))); 
  $b -= $c; $b -= $a; toInt32($b); $b = (int)($b ^ ($a<<10)); 
  $c -= $a; $c -= $b; toInt32($c); $c = (int)($c ^ (zeroFill($b,15))); 
   
  return array($a,$b,$c);
}

function GoogleCH($url, $length=null, $init=GOOGLE_MAGIC) {
    if(is_null($length)) {
        $length = sizeof($url);
    }
    $a = $b = 0x9E3779B9;
    $c = $init;
    $k = 0;
    $len = $length;
    while($len >= 12) {
        $a += ($url[$k+0] +($url[$k+1]<<8) +($url[$k+2]<<16) +($url[$k+3]<<24));
        $b += ($url[$k+4] +($url[$k+5]<<8) +($url[$k+6]<<16) +($url[$k+7]<<24));
        $c += ($url[$k+8] +($url[$k+9]<<8) +($url[$k+10]<<16)+($url[$k+11]<<24));
        $mix = mix($a,$b,$c);
        $a = $mix[0]; $b = $mix[1]; $c = $mix[2];
        $k += 12;
        $len -= 12;
    }

    $c += $length;
    switch($len)
    {
        case 11: $c+=($url[$k+10]<<24);
        case 10: $c+=($url[$k+9]<<16);
        case 9 : $c+=($url[$k+8]<<8);
        case 8 : $b+=($url[$k+7]<<24);
        case 7 : $b+=($url[$k+6]<<16);
        case 6 : $b+=($url[$k+5]<<8);
        case 5 : $b+=($url[$k+4]);
        case 4 : $a+=($url[$k+3]<<24);
        case 3 : $a+=($url[$k+2]<<16);
        case 2 : $a+=($url[$k+1]<<8);
        case 1 : $a+=($url[$k+0]);
    }
    $mix = mix($a,$b,$c);
    return $mix[2];
}

function strord($string) {
    for($i=0;$i<strlen($string);$i++) {
        $result[$i] = ord($string{$i});
    }
    return $result;
}

function getrank($url) {
    $url = 'info:'.$url;
    $ch = GoogleCH(strord($url));
    $file = "http://www.google.com/search?client=navclient-auto&ch=6$ch&features=Rank&q=$url";
    $data = file($file);
    $rankarray = explode (':', $data[2]);
    $rank = $rankarray[2];
    return $rank;
}
if(!$_GET['url']) {
$pr_rank = "Page rank could not be displayed!";
} else {
$url = "http://www.".$_GET['url'];
$pr_rank = getrank($url);
}
print '
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-9" />
<title>Google Page Rank</title>
</head>
<body>
<table width="100%" border="0" cellpadding="2" cellspacing="0" bgcolor="#FFFFFF">
  <tr> 
    <td colspan="2"><h1>Google PageRank for: '. $_GET[url].'</h1></td>
  </tr>
  <tr> 
    <td width="30%">Google page rank:</td>
    <td width="70%">'.$pr_rank.'</td>
  </tr>
</table>
</body>
</html>';
?>
burda yapılan işlem nedir birisi kısaca anlatabilir mi