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      1 /*
      2  * Javassist, a Java-bytecode translator toolkit.
      3  * Copyright (C) 1999-2007 Shigeru Chiba. All Rights Reserved.
      4  *
      5  * The contents of this file are subject to the Mozilla Public License Version
      6  * 1.1 (the "License"); you may not use this file except in compliance with
      7  * the License.  Alternatively, the contents of this file may be used under
      8  * the terms of the GNU Lesser General Public License Version 2.1 or later.
      9  *
     10  * Software distributed under the License is distributed on an "AS IS" basis,
     11  * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
     12  * for the specific language governing rights and limitations under the
     13  * License.
     14  */
     15 
     16 package javassist.bytecode;
     17 
     18 /**
     19  * A collection of static methods for reading and writing a byte array.
     20  */
     21 public class ByteArray {
     22     /**
     23      * Reads an unsigned 16bit integer at the index.
     24      */
     25     public static int readU16bit(byte[] code, int index) {
     26         return ((code[index] & 0xff) << 8) | (code[index + 1] & 0xff);
     27     }
     28 
     29     /**
     30      * Reads a signed 16bit integer at the index.
     31      */
     32     public static int readS16bit(byte[] code, int index) {
     33         return (code[index] << 8) | (code[index + 1] & 0xff);
     34     }
     35 
     36     /**
     37      * Writes a 16bit integer at the index.
     38      */
     39     public static void write16bit(int value, byte[] code, int index) {
     40         code[index] = (byte)(value >>> 8);
     41         code[index + 1] = (byte)value;
     42     }
     43 
     44     /**
     45      * Reads a 32bit integer at the index.
     46      */
     47     public static int read32bit(byte[] code, int index) {
     48         return (code[index] << 24) | ((code[index + 1] & 0xff) << 16)
     49                | ((code[index + 2] & 0xff) << 8) | (code[index + 3] & 0xff);
     50     }
     51 
     52     /**
     53      * Writes a 32bit integer at the index.
     54      */
     55     public static void write32bit(int value, byte[] code, int index) {
     56         code[index] = (byte)(value >>> 24);
     57         code[index + 1] = (byte)(value >>> 16);
     58         code[index + 2] = (byte)(value >>> 8);
     59         code[index + 3] = (byte)value;
     60     }
     61 
     62     /**
     63      * Copies a 32bit integer.
     64      *
     65      * @param src       the source byte array.
     66      * @param isrc      the index into the source byte array.
     67      * @param dest      the destination byte array.
     68      * @param idest     the index into the destination byte array.
     69      */
     70     static void copy32bit(byte[] src, int isrc, byte[] dest, int idest) {
     71         dest[idest] = src[isrc];
     72         dest[idest + 1] = src[isrc + 1];
     73         dest[idest + 2] = src[isrc + 2];
     74         dest[idest + 3] = src[isrc + 3];
     75     }
     76 }
     77