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Java > Open Source Codes > com > martiansoftware > nailgun > LongUtils


1 /*
2
3   Copyright 2004, Martian Software, Inc.
4
5   Licensed under the Apache License, Version 2.0 (the "License");
6   you may not use this file except in compliance with the License.
7   You may obtain a copy of the License at
8
9   http://www.apache.org/licenses/LICENSE-2.0
10
11   Unless required by applicable law or agreed to in writing, software
12   distributed under the License is distributed on an "AS IS" BASIS,
13   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14   See the License for the specific language governing permissions and
15   limitations under the License.
16   
17 */
18
19 package com.martiansoftware.nailgun;
20
21 /**
22  * Provides a couple of utility methods that help in reading/writin
23  * chunks of data in the Nailgun protocol.
24  *
25  * @author <a HREF="http://www.martiansoftware.com/contact.html">Marty Lamb</a>
26  */
27 class LongUtils {
28
29     /**
30      * Encodes the specified long in 4 consecutive bytes (big-endian)
31      * in the specified array, beginning at the specified offset.
32      * @param l the long to encode
33      * @param b the array into which the long should be written
34      * @param offset the offset into the array at which the writing
35      * should begin
36      */
37     public static void toArray(long l, byte[] b, int offset) {
38         b[offset + 3] = (byte) (l % 256);
39         l >>>= 8;
40         b[offset + 2] = (byte) (l % 256);
41         l >>>= 8;
42         b[offset + 1] = (byte) (l % 256);
43         l >>>= 8;
44         b[0] = (byte) (l % 256);
45     }
46     
47     /**
48      * Reads a 4-byte big-endian long from the specified array,
49      * beginnin at the specified offset.
50      * @param b the array containing the encoded long
51      * @param offset the offset into the array at which the encoded
52      * long begins
53      * @return the decoded long
54      */
55     public static long fromArray(byte[] b, int offset) {
56         return(((long) (b[offset] & 0xff) << 24)
57                 + ((long) (b[offset + 1] & 0xff) << 16)
58                 + ((long) (b[offset + 2] & 0xff) << 8)
59                 + ((long) (b[offset + 3] & 0xff)));
60     }
61 }
62
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