KickJava   Java API By Example, From Geeks To Geeks.

Java > Open Source Codes > javassist > bytecode > ByteArray


1 /*
2  * Javassist, a Java-bytecode translator toolkit.
3  * Copyright (C) 1999-2005 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
Popular Tags