--- /t3lib/class.t3lib_div.php	2010-02-26 18:40:53 (Revision 7091)
+++ /t3lib/class.t3lib_div.php	2010-03-09 00:02:16
@@ -1216,39 +1216,33 @@
 	}
 
 	/**
-	 * Formats the input integer $sizeInBytes as bytes/kilobytes/megabytes (-/K/M)
+	 * Formats the input integer $sizeInBytes as bytes/kilobytes/megabytes (-/K/M) and beyond (theoretically infinite)
 	 * Usage: 53
 	 *
-	 * @param	integer		Number of bytes to format.
-	 * @param	string		Labels for bytes, kilo, mega and giga separated by vertical bar (|) and possibly encapsulated in "". Eg: " | K| M| G" (which is the default value)
-	 * @return	string		Formatted representation of the byte number, for output.
+	 * @param  integer Number of bytes to format.
+	 * @param  string  Labels for bytes, kilo, mega and giga separated by vertical bar (|) and possibly encapsulated in "". Eg: " B| KB| MB| GB | TB" (default value)
+	 * @return string  Formatted representation of the byte number, for output (label is suffixed).
 	 */
-	public static function formatSize($sizeInBytes,$labels='')	{
-
-			// Set labels:
+	public static function formatSize($sizeInBytes,$labels='') {
+		$default_format = 'traditional'; // should be moved to config_default.php, like $TYPO3_CONF_VARS['SYS']['ddmmyy'] and ['hhmm']
+		$defaults = array(
+			'traditional' => array('base' => 1024, 'labels' => ' B| KB| MB| GB | TB'),
+			'iec'         => array('base' => 1024, 'labels' => ' B| KiB| MiB| GiB | TiB'),
+			'si'          => array('base' => 1000, 'labels' => ' B| kB| MB| GB | TB')
+		);
+		if (!array_key_exists($default_format, $defaults)) { $default_format = 'traditional'; }
+		
+		// Set labels:
 		if (strlen($labels) == 0) {
-			$labels = ' | K| M| G';
+			$labels = $defaults[$default_format]['labels'];
 		} else {
 			$labels = str_replace('"','',$labels);
 		}
 		$labelArr = explode('|',$labels);
-
-			// Find size:
-		if ($sizeInBytes>900)	{
-			if ($sizeInBytes>900000000)	{	// GB
-				$val = $sizeInBytes/(1024*1024*1024);
-				return number_format($val, (($val<20)?1:0), '.', '').$labelArr[3];
-			}
-			elseif ($sizeInBytes>900000)	{	// MB
-				$val = $sizeInBytes/(1024*1024);
-				return number_format($val, (($val<20)?1:0), '.', '').$labelArr[2];
-			} else {	// KB
-				$val = $sizeInBytes/(1024);
-				return number_format($val, (($val<20)?1:0), '.', '').$labelArr[1];
-			}
-		} else {	// Bytes
-			return $sizeInBytes.$labelArr[0];
-		}
+		
+		$exponent = floor(log($sizeInBytes, $defaults[$default_format]['base']));                       // determine the exponent for further calculations
+		if ($sizeInBytes > (pow($defaults[$default_format]['base'], $exponent+1)*0.9)) { $exponent++; } // use next higher unit if the size is greater than the threshold (90 % of next unit)
+		return @number_format($sizeInBytes/pow($defaults[$default_format]['base'], $exponent), (($exponent!=0)?2:0)) . ' ' . $labelArr[$exponent]; // output and round to 2 significant decimals
 	}
 
 	/**