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
16package javassist.bytecode;
17
18/**
19 * A collection of static methods for reading and writing a byte array.
20 */
21public 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