Clarified comment per CR r111701

diff --git a/includes/HistoryBlob.php b/includes/HistoryBlob.php
index 7887ff8..9e63791 100644 (file)
--- a/includes/HistoryBlob.php
+++ b/includes/HistoryBlob.php
@@ -567,10 +567,11 @@ class DiffHistoryBlob implements HistoryBlob {
        function xdiffAdler32( $s ) {
                static $init;
                if ( $init === null ) {
-                       // The real Adler-32 checksum of this string is zero, so it 
-                       // initialises the state to the LibXDiff initial value.
                        $init = str_repeat( "\xf0", 205 ) . "\xee" . str_repeat( "\xf0", 67 ) . "\x02";
                }
+               // The real Adler-32 checksum of $init is zero, so it initialises the 
+               // state to zero, as it is at the start of LibXDiff's checksum 
+               // algorithm. Appending the subject string then simulates LibXDiff.
                if ( function_exists( 'hash' ) ) {
                        $hash = hash( 'adler32', $init . $s, true );
                } elseif ( function_exists( 'mhash' ) ) {