001 /*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements. See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License. You may obtain a copy of the License at
008 *
009 * http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017 package org.apache.commons.lang3;
018
019 /**
020 * <p>Operations on bit-mapped fields.</p>
021 *
022 * @since 2.0
023 * @version $Id: BitField.java 1088899 2011-04-05 05:31:27Z bayard $
024 */
025 public class BitField {
026
027 private final int _mask;
028 private final int _shift_count;
029
030 /**
031 * <p>Creates a BitField instance.</p>
032 *
033 * @param mask the mask specifying which bits apply to this
034 * BitField. Bits that are set in this mask are the bits
035 * that this BitField operates on
036 */
037 public BitField(int mask) {
038 _mask = mask;
039 int count = 0;
040 int bit_pattern = mask;
041
042 if (bit_pattern != 0) {
043 while ((bit_pattern & 1) == 0) {
044 count++;
045 bit_pattern >>= 1;
046 }
047 }
048 _shift_count = count;
049 }
050
051 /**
052 * <p>Obtains the value for the specified BitField, appropriately
053 * shifted right.</p>
054 *
055 * <p>Many users of a BitField will want to treat the specified
056 * bits as an int value, and will not want to be aware that the
057 * value is stored as a BitField (and so shifted left so many
058 * bits).</p>
059 *
060 * @see #setValue(int,int)
061 * @param holder the int data containing the bits we're interested
062 * in
063 * @return the selected bits, shifted right appropriately
064 */
065 public int getValue(int holder) {
066 return getRawValue(holder) >> _shift_count;
067 }
068
069 /**
070 * <p>Obtains the value for the specified BitField, appropriately
071 * shifted right, as a short.</p>
072 *
073 * <p>Many users of a BitField will want to treat the specified
074 * bits as an int value, and will not want to be aware that the
075 * value is stored as a BitField (and so shifted left so many
076 * bits).</p>
077 *
078 * @see #setShortValue(short,short)
079 * @param holder the short data containing the bits we're
080 * interested in
081 * @return the selected bits, shifted right appropriately
082 */
083 public short getShortValue(short holder) {
084 return (short) getValue(holder);
085 }
086
087 /**
088 * <p>Obtains the value for the specified BitField, unshifted.</p>
089 *
090 * @param holder the int data containing the bits we're
091 * interested in
092 * @return the selected bits
093 */
094 public int getRawValue(int holder) {
095 return holder & _mask;
096 }
097
098 /**
099 * <p>Obtains the value for the specified BitField, unshifted.</p>
100 *
101 * @param holder the short data containing the bits we're
102 * interested in
103 * @return the selected bits
104 */
105 public short getShortRawValue(short holder) {
106 return (short) getRawValue(holder);
107 }
108
109 /**
110 * <p>Returns whether the field is set or not.</p>
111 *
112 * <p>This is most commonly used for a single-bit field, which is
113 * often used to represent a boolean value; the results of using
114 * it for a multi-bit field is to determine whether *any* of its
115 * bits are set.</p>
116 *
117 * @param holder the int data containing the bits we're interested
118 * in
119 * @return {@code true} if any of the bits are set,
120 * else {@code false}
121 */
122 public boolean isSet(int holder) {
123 return (holder & _mask) != 0;
124 }
125
126 /**
127 * <p>Returns whether all of the bits are set or not.</p>
128 *
129 * <p>This is a stricter test than {@link #isSet(int)},
130 * in that all of the bits in a multi-bit set must be set
131 * for this method to return {@code true}.</p>
132 *
133 * @param holder the int data containing the bits we're
134 * interested in
135 * @return {@code true} if all of the bits are set,
136 * else {@code false}
137 */
138 public boolean isAllSet(int holder) {
139 return (holder & _mask) == _mask;
140 }
141
142 /**
143 * <p>Replaces the bits with new values.</p>
144 *
145 * @see #getValue(int)
146 * @param holder the int data containing the bits we're
147 * interested in
148 * @param value the new value for the specified bits
149 * @return the value of holder with the bits from the value
150 * parameter replacing the old bits
151 */
152 public int setValue(int holder, int value) {
153 return (holder & ~_mask) | ((value << _shift_count) & _mask);
154 }
155
156 /**
157 * <p>Replaces the bits with new values.</p>
158 *
159 * @see #getShortValue(short)
160 * @param holder the short data containing the bits we're
161 * interested in
162 * @param value the new value for the specified bits
163 * @return the value of holder with the bits from the value
164 * parameter replacing the old bits
165 */
166 public short setShortValue(short holder, short value) {
167 return (short) setValue(holder, value);
168 }
169
170 /**
171 * <p>Clears the bits.</p>
172 *
173 * @param holder the int data containing the bits we're
174 * interested in
175 * @return the value of holder with the specified bits cleared
176 * (set to {@code 0})
177 */
178 public int clear(int holder) {
179 return holder & ~_mask;
180 }
181
182 /**
183 * <p>Clears the bits.</p>
184 *
185 * @param holder the short data containing the bits we're
186 * interested in
187 * @return the value of holder with the specified bits cleared
188 * (set to {@code 0})
189 */
190 public short clearShort(short holder) {
191 return (short) clear(holder);
192 }
193
194 /**
195 * <p>Clears the bits.</p>
196 *
197 * @param holder the byte data containing the bits we're
198 * interested in
199 *
200 * @return the value of holder with the specified bits cleared
201 * (set to {@code 0})
202 */
203 public byte clearByte(byte holder) {
204 return (byte) clear(holder);
205 }
206
207 /**
208 * <p>Sets the bits.</p>
209 *
210 * @param holder the int data containing the bits we're
211 * interested in
212 * @return the value of holder with the specified bits set
213 * to {@code 1}
214 */
215 public int set(int holder) {
216 return holder | _mask;
217 }
218
219 /**
220 * <p>Sets the bits.</p>
221 *
222 * @param holder the short data containing the bits we're
223 * interested in
224 * @return the value of holder with the specified bits set
225 * to {@code 1}
226 */
227 public short setShort(short holder) {
228 return (short) set(holder);
229 }
230
231 /**
232 * <p>Sets the bits.</p>
233 *
234 * @param holder the byte data containing the bits we're
235 * interested in
236 *
237 * @return the value of holder with the specified bits set
238 * to {@code 1}
239 */
240 public byte setByte(byte holder) {
241 return (byte) set(holder);
242 }
243
244 /**
245 * <p>Sets a boolean BitField.</p>
246 *
247 * @param holder the int data containing the bits we're
248 * interested in
249 * @param flag indicating whether to set or clear the bits
250 * @return the value of holder with the specified bits set or
251 * cleared
252 */
253 public int setBoolean(int holder, boolean flag) {
254 return flag ? set(holder) : clear(holder);
255 }
256
257 /**
258 * <p>Sets a boolean BitField.</p>
259 *
260 * @param holder the short data containing the bits we're
261 * interested in
262 * @param flag indicating whether to set or clear the bits
263 * @return the value of holder with the specified bits set or
264 * cleared
265 */
266 public short setShortBoolean(short holder, boolean flag) {
267 return flag ? setShort(holder) : clearShort(holder);
268 }
269
270 /**
271 * <p>Sets a boolean BitField.</p>
272 *
273 * @param holder the byte data containing the bits we're
274 * interested in
275 * @param flag indicating whether to set or clear the bits
276 * @return the value of holder with the specified bits set or
277 * cleared
278 */
279 public byte setByteBoolean(byte holder, boolean flag) {
280 return flag ? setByte(holder) : clearByte(holder);
281 }
282
283 }