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
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
|
<?php
/**
* PHP Reader Library
*
* Copyright (c) 2008 The PHP Reader Project Workgroup. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* - Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* - Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
* - Neither the name of the project workgroup nor the names of its
* contributors may be used to endorse or promote products derived from this
* software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
* @package php-reader
* @copyright Copyright (c) 2008 The PHP Reader Project Workgroup
* @license http://code.google.com/p/php-reader/wiki/License New BSD License
* @version $Id: Twiddling.php 110 2008-09-05 17:10:51Z svollbehr $
*/
/**
* A utility class to perform bit twiddling on integers.
*
* @package php-reader
* @author Ryan Butterfield <buttza@gmail.com>
* @copyright Copyright (c) 2008 The PHP Reader Project Workgroup
* @license http://code.google.com/p/php-reader/wiki/License New BSD License
* @version $Rev: 110 $
* @static
*/
final class Twiddling
{
/**
* Default private constructor for a static class.
*/
private function __construct() {}
/**
* Sets a bit at a given position in an integer.
*
* @param integer $integer The value to manipulate.
* @param integer $position The position of the bit to set.
* @param boolean $on Whether to enable or clear the bit.
* @return integer
*/
public static function setBit($integer, $position, $on)
{
return $on ? self::enableBit($integer, $position) :
self::clearBit($integer, $position);
}
/**
* Enables a bit at a given position in an integer.
*
* @param integer $integer The value to manipulate.
* @param integer $position The position of the bit to enable.
* @return integer
*/
public static function enableBit($integer, $position)
{
return $integer | (1 << $position);
}
/**
* Clears a bit at a given position in an integer.
*
* @param integer $integer The value to manipulate.
* @param integer $position The position of the bit to clear.
* @return integer
*/
public static function clearBit($integer, $position)
{
return $integer & ~(1 << $position);
}
/**
* Toggles a bit at a given position in an integer.
*
* @param integer $integer The value to manipulate.
* @param integer $position The position of the bit to toggle.
* @return integer
*/
public static function toggleBit($integer, $position)
{
return $integer ^ (1 << $position);
}
/**
* Tests a bit at a given position in an integer.
*
* @param integer $integer The value to test.
* @param integer $position The position of the bit to test.
* @return boolean
*/
public static function testBit($integer, $position)
{
return ($integer & (1 << $position)) != 0;
}
/**
* Sets a given set of bits in an integer.
*
* @param integer $integer The value to manipulate.
* @param integer $bits The bits to set.
* @param boolean $on Whether to enable or clear the bits.
* @return integer
*/
public static function setBits($integer, $bits, $on)
{
return $on ? self::enableBits($integer, $bits) :
self::clearBits($integer, $bits);
}
/**
* Enables a given set of bits in an integer.
*
* @param integer $integer The value to manipulate.
* @param integer $bits The bits to enable.
* @return integer
*/
public static function enableBits($integer, $bits)
{
return $integer | $bits;
}
/**
* Clears a given set of bits in an integer.
*
* @param integer $integer The value to manipulate.
* @param integer $bits The bits to clear.
* @return integer
*/
public static function clearBits($integer, $bits)
{
return $integer & ~$bits;
}
/**
* Toggles a given set of bits in an integer.
*
* @param integer $integer The value to manipulate.
* @param integer $bits The bits to toggle.
* @return integer
*/
public static function toggleBits($integer, $bits)
{
return $integer ^ $bits;
}
/**
* Tests a given set of bits in an integer
* returning whether all bits are set.
*
* @param integer $integer The value to test.
* @param integer $bits The bits to test.
* @return boolean
*/
public static function testAllBits($integer, $bits)
{
return ($integer & $bits) == $bits;
}
/**
* Tests a given set of bits in an integer
* returning whether any bits are set.
*
* @param integer $integer The value to test.
* @param integer $bits The bits to test.
* @return boolean
*/
public static function testAnyBits($integer, $bits)
{
return ($integer & $bits) != 0;
}
/**
* Stores a value in a given range in an integer.
*
* @param integer $integer The value to store into.
* @param integer $start The position to store from. Must be <= $end.
* @param integer $end The position to store to. Must be >= $start.
* @param integer $value The value to store.
* @return integer
*/
public static function setValue($integer, $start, $end, $value)
{
return self::clearBits($integer, self::getMask($start, $end) << $start) |
($value << $start);
}
/**
* Retrieves a value from a given range in an integer, inclusive.
*
* @param integer $integer The value to read from.
* @param integer $start The position to read from. Must be <= $end.
* @param integer $end The position to read to. Must be >= $start.
* @return integer
*/
public static function getValue($integer, $start, $end)
{
return ($integer & self::getMask($start, $end)) >> $start;
}
/**
* Returns an integer with all bits set from start to end.
*
* @param integer $start The position to start setting bits from. Must
* be <= $end.
* @param integer $end The position to stop setting bits. Must be >= $start.
* @return integer
*/
public static function getMask($start, $end)
{
$mask = 0;
for (; $start <= $end; $start++)
$mask |= 1 << $start;
return $mask;
}
}
|
