Bitwise operators are architecture dependent.
And -4738698913 is actually not an integer, but a float on 32bit platform.

Yes, they are dependent to a point.  But in 5.0.4 they returned the same end value.

Something has changed in 5.1.x that no longer produces the correct value.

Here is the code that had worked under 5.0.4 Windows / linux:

<?php

define('GOOGLE_MAGIC', 0xE6359A60);

	class googleTools{

		public static $url;

		public function __construct($url = false){



		}

		public 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));
		        $mix = googleTools::mix($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 */
		    }
		    $mix = googleTools::mix($a,$b,$c);
		    /*-------------------------------------------- report the result */

		    return $mix[2];
		}

		public function doGetRank($url) {




		   	$url = 'info:'.$url;
		   	$GoogleCH = googleTools::GoogleCH(googleTools::strord($url));
				$url = urlencode($url);
		    $file = "http://www.google.com/search?client=navclient-auto&ch=6$GoogleCH&features=Rank&q=$url";
		    //$data = file($file);

		    $ch = curl_init();    // initialize curl handle
				curl_setopt($ch, CURLOPT_URL,$file); // set url to post to
				curl_setopt($ch, CURLOPT_FAILONERROR, 1);
				curl_setopt($ch, CURLOPT_FOLLOWLOCATION, 1);// allow redirects
				curl_setopt($ch, CURLOPT_RETURNTRANSFER,1); // return into a variable
				curl_setopt($ch, CURLOPT_TIMEOUT, 25); // times out after 4s
				$data = curl_exec($ch); // run the whole process
				curl_close($ch);
		    $rankarray = explode (':', $data);
		    $rank = $rankarray[2];

		    return $rank;
		}

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


		}

		//unsigned shift right
		private function zeroFill($a, $b)
		{
			$aTemp =$a;
		    $z = hexdec(80000000);
		        if ($z & $a)
		        {
		            $a = ($a>>1);
		            $a &= (~$z);
		            $a |= 0x40000000;
		            $a = ($a>>($b-1));
		        }
		        else
		        {
		            $a = ($a>>$b);
		        }

		        return $a;


		}

		private function mix($a,$b,$c) {
		  $a -= $b; $a -= $c; $aTemp = $a; $a ^= (googleTools::zeroFill($c,13));
		  $b -= $c; $b -= $a; $b ^= ($a<<8);
		  $c -= $a; $c -= $b; $c ^= (googleTools::zeroFill($b,13));
		  $a -= $b; $a -= $c; $a ^= (googleTools::zeroFill($c,12));
		  $b -= $c; $b -= $a; $b ^= ($a<<16);
		  $c -= $a; $c -= $b; $c ^= (googleTools::zeroFill($b,5));
		  $a -= $b; $a -= $c; $a ^= (googleTools::zeroFill($c,3));
		  $b -= $c; $b -= $a; $b ^= ($a<<10);
		  $c -= $a; $c -= $b; $c ^= (googleTools::zeroFill($b,15));

		  $arr = array($a,$b,$c);
		  print_a($arr);

		  return $arr;
		}

	}

?>

your first test returns "-4738672007" on Linux 64 bit. PHP_5_2 CVS.

>Something has changed in 5.1.x that no longer produces the correct value.
Your server has changed.

Confirmed.  I have just up graded on a FC2 machine from 5.0.4 to 5.1.4 and the result is correct.  Well, back to the investigation as to why every server but my production server gives the correct value :(

Is there a specific extension that governs this type of math functions? Maybe a library needs updating or I  didn't enable it when I compiled.

Thanks for your help.