<?php  
/*  
    This code is released unto the public domain  
*/  
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;  
}  
// http://www.example.com/ - Checksum: 6540747202  
$url = 'info:'.$_GET['url'];  
print("url:\t{$_GET['url']}\n");  
$ch = GoogleCH(strord($url));  
printf("ch:\t6%u\n",$ch);  
?>