blob: 2da39f86196548a8c0123115ec2b37251eea3f6e (
plain)
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
|
/* Copyright © 2000 Free Software Foundation
This file is part of libgcj.
This software is copyrighted work licensed under the terms of the
Libgcj License. Please consult the file "LIBGCJ_LICENSE" for
details. */
package gnu.gcj.awt;
/**
* Simple transparent utility class that can be used to perform bit
* mask extent calculations.
*/
public final class BitMaskExtent
{
/** The number of the least significant bit of the bit mask extent. */
public byte leastSignificantBit;
/** The number of bits in the bit mask extent. */
public byte bitWidth;
/**
* Set the bit mask. This will calculate and set the leastSignificantBit
* and bitWidth fields.
*
* @see #leastSignificantBit
* @see #bitWidth
*/
public void setMask(long mask)
{
leastSignificantBit = 0;
bitWidth = 0;
if (mask == 0) return;
long shiftMask = mask;
for (; (shiftMask&1) == 0; shiftMask >>>=1) leastSignificantBit++;
for (; (shiftMask&1) != 0; shiftMask >>>=1) bitWidth++;
if (shiftMask != 0)
throw new IllegalArgumentException("mask must be continuous");
}
/**
* Calculate the bit mask based on the values of the
* leastSignificantBit and bitWidth fields.
*/
public long toMask()
{
return ((1<<bitWidth)-1) << leastSignificantBit;
}
}
|
