1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
|
/*
* Copyright 2006-2012 Amazon Technologies, Inc. or its affiliates.
* Amazon, Amazon.com and Carbonado are trademarks or registered trademarks
* of Amazon Technologies, Inc. or its affiliates. All rights reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.amazon.carbonado.raw;
/**
* Utilities for manipulating binary data.
*
* @author Brian S O'Neill
*/
public class RawUtil {
/**
* Adds one to an unsigned integer, represented as a byte array. If
* overflowed, value in byte array is 0x00, 0x00, 0x00...
*
* @param value unsigned integer to increment
* @return false if overflowed
*/
public static boolean increment(byte[] value) {
for (int i=value.length; --i>=0; ) {
byte newValue = (byte) ((value[i] & 0xff) + 1);
value[i] = newValue;
if (newValue != 0) {
// No carry bit, so done adding.
return true;
}
}
// This point is reached upon overflow.
return false;
}
/**
* Subtracts one from an unsigned integer, represented as a byte array. If
* overflowed, value in byte array is 0xff, 0xff, 0xff...
*
* @param value unsigned integer to decrement
* @return false if overflowed
*/
public static boolean decrement(byte[] value) {
for (int i=value.length; --i>=0; ) {
byte newValue = (byte) ((value[i] & 0xff) + -1);
value[i] = newValue;
if (newValue != -1) {
// No borrow bit, so done subtracting.
return true;
}
}
// This point is reached upon overflow.
return false;
}
}
|
