구글의 PageRank

    1. 데모

    2. 코드

    <?php
    /*
            Written and contributed by
            Alex Stapleton,
            Andy Doctorow,
            Tarakan,
            Bill Zeller,
            Vijay "Cyberax" Bhatter
            traB
        This code is released into the public domain
    */
    header("Content-Type: text/plain; charset=utf-8");
    define('GOOGLE_MAGIC', 0xE6359A60);

    //unsigned shift right
    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; $a ^= (zeroFill($c,13));
      $b -= $c; $b -= $a; $b ^= ($a<<8);
      $c -= $a; $c -= $b; $c ^= (zeroFill($b,13));
      $a -= $b; $a -= $c; $a ^= (zeroFill($c,12));
      $b -= $c; $b -= $a; $b ^= ($a<<16);
      $c -= $a; $c -= $b; $c ^= (zeroFill($b,5));
      $a -= $b; $a -= $c; $a ^= (zeroFill($c,3));  
      $b -= $c; $b -= $a; $b ^= ($a<<10);
      $c -= $a; $c -= $b; $c ^= (zeroFill($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)              /* all the case statements fall through */
        {
            case 11: $c+=($url[$k+10]<<24);
            case 10: $c+=($url[$k+9]<<16);
            case 9 : $c+=($url[$k+8]<<8);
              /* the first byte of c is reserved for the length */
            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]);
             /* case 0: nothing left to add */
        }
        $mix = mix($a,$b,$c);
        /*-------------------------------------------- report the result */
        return $mix[2];
    }

    //converts a string into an array of integers containing the numeric value of the char
    function strord($string) {
        for($i=0;$i<strlen($string);$i++) {
            $result[$i] = ord($string{$i});
        }
        return $result;
    }


    // converts an array of 32 bit integers into an array with 8 bit values. Equivalent to (BYTE *)arr32

    function c32to8bit($arr32) {
        for($i=0;$i<count($arr32);$i++) {
            for ($bitOrder=$i*4;$bitOrder<=$i*4+3;$bitOrder++) {
                $arr8[$bitOrder]=$arr32[$i]&255;
                $arr32[$i]=zeroFill($arr32[$i], 8);
            }    
        }
        return $arr8;
    }

    $u = $_GET['url'];

    echo "
    <html><head><title>Google PageRank</title></head>
    <body>
    <form>
    <input type=text name=url value='$u' size=60><input type=submit value='PageRank'>
    </form>
    ";

    if(!empty($u)){

    // http://www.example.com/ - Checksum: 6540747202
    $url = 'info:'.$_GET['url'];
    print("url:\t{$_GET['url']}\n");
    $ch = GoogleCH(strord($url));
    printf("Checksum <2.0.114:\t6%u\n",$ch);

    $ch=sprintf("%u", $ch);
    // new since Toolbar 2.0.114

    $ch = ((($ch/7) << 2) | (((int)fmod($ch,13))&7));

    $prbuf = array();
    $prbuf[0] = $ch;
    for($i = 1; $i < 20; $i++) {
          $prbuf[$i] = $prbuf[$i-1]-9;
    }
    $ch = GoogleCH(c32to8bit($prbuf), 80);
    //

    printf("Checksum >=2.0.114:\t6%u\n",$ch);

    /*
    http://www.google.com/ search?client=navclient-auto&ch=[checksum here] &features=Rank&q=info:http://www.example.com
    */

    $url = sprintf("http://www.google.com/search?client=navclient-auto&ch=6%u&features=Rank&q=%s",$ch,$url);

    echo "<p><a href='$url' target='_blank'>$url</a></p>";
    echo "</body></html>";
    }

    ?>

    Posted by 부니기