MediaWiki 1.30.2

[autoinstallsdev/mediawiki.git] / vendor / wikimedia / cdb / src / Util.php

diff --git a/vendor/wikimedia/cdb/src/Util.php b/vendor/wikimedia/cdb/src/Util.php
new file mode 100644 (file)
index 0000000..fe19509
--- /dev/null
+++ b/vendor/wikimedia/cdb/src/Util.php
@@ -0,0 +1,100 @@
+<?php
+
+namespace Cdb;
+
+/**
+ * This is a port of D.J. Bernstein's CDB to PHP. It's based on the copy that
+ * appears in PHP 5.3. Changes are:
+ *    * Error returns replaced with exceptions
+ *    * Exception thrown if sizes or offsets are between 2GB and 4GB
+ *    * Some variables renamed
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ */
+
+/**
+ * Common functions for readers and writers
+ */
+class Util {
+       /**
+        * Take a modulo of a signed integer as if it were an unsigned integer.
+        * $b must be less than 0x40000000 and greater than 0
+        *
+        * @param int $a
+        * @param int $b
+        *
+        * @return int
+        */
+       public static function unsignedMod( $a, $b ) {
+               if ( $a & 0x80000000 ) {
+                       $m = ( $a & 0x7fffffff ) % $b + 2 * ( 0x40000000 % $b );
+
+                       return $m % $b;
+               } else {
+                       return $a % $b;
+               }
+       }
+
+       /**
+        * Shift a signed integer right as if it were unsigned
+        * @param int $a
+        * @param int $b
+        * @return int
+        */
+       public static function unsignedShiftRight( $a, $b ) {
+               if ( $b == 0 ) {
+                       return $a;
+               }
+               if ( $a & 0x80000000 ) {
+                       return ( ( $a & 0x7fffffff ) >> $b ) | ( 0x40000000 >> ( $b - 1 ) );
+               } else {
+                       return $a >> $b;
+               }
+       }
+
+       /**
+        * The CDB hash function.
+        *
+        * @param string $s
+        *
+        * @return int
+        */
+       public static function hash( $s ) {
+               $h = 5381;
+               $len = strlen( $s );
+               for ( $i = 0; $i < $len; $i++ ) {
+                       $h5 = ( $h << 5 ) & 0xffffffff;
+                       // Do a 32-bit sum
+                       // Inlined here for speed
+                       $sum = ( $h & 0x3fffffff ) + ( $h5 & 0x3fffffff );
+                       $h =
+                               (
+                                       ( $sum & 0x40000000 ? 1 : 0 )
+                                       + ( $h & 0x80000000 ? 2 : 0 )
+                                       + ( $h & 0x40000000 ? 1 : 0 )
+                                       + ( $h5 & 0x80000000 ? 2 : 0 )
+                                       + ( $h5 & 0x40000000 ? 1 : 0 )
+                               ) << 30
+                               | ( $sum & 0x3fffffff );
+                       $h ^= ord( $s[$i] );
+                       $h &= 0xffffffff;
+               }
+
+               return $h;
+       }
+}