001    /**
002     * Licensed to the Apache Software Foundation (ASF) under one
003     * or more contributor license agreements.  See the NOTICE file
004     * distributed with this work for additional information
005     * regarding copyright ownership.  The ASF licenses this file
006     * to you under the Apache License, Version 2.0 (the
007     * "License"); you may not use this file except in compliance
008     * with the License.  You may obtain a copy of the License at
009     *
010     *     http://www.apache.org/licenses/LICENSE-2.0
011     *
012     * Unless required by applicable law or agreed to in writing, software
013     * distributed under the License is distributed on an "AS IS" BASIS,
014     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015     * See the License for the specific language governing permissions and
016     * limitations under the License.
017     */
018    package org.apache.hadoop.hdfs.util;
019    
020    import java.io.Serializable;
021    
022    
023    /**
024     * Bit format in a long.
025     */
026    public class LongBitFormat implements Serializable {
027      private static final long serialVersionUID = 1L;
028    
029      private final String NAME;
030      /** Bit offset */
031      private final int OFFSET;
032      /** Bit length */
033      private final int LENGTH;
034      /** Minimum value */
035      private final long MIN;
036      /** Maximum value */
037      private final long MAX;
038      /** Bit mask */
039      private final long MASK;
040    
041      public LongBitFormat(String name, LongBitFormat previous, int length, long min) {
042        NAME = name;
043        OFFSET = previous == null? 0: previous.OFFSET + previous.LENGTH;
044        LENGTH = length;
045        MIN = min;
046        MAX = ((-1L) >>> (64 - LENGTH));
047        MASK = MAX << OFFSET;
048      }
049    
050      /** Retrieve the value from the record. */
051      public long retrieve(long record) {
052        return (record & MASK) >>> OFFSET;
053      }
054    
055      /** Combine the value to the record. */
056      public long combine(long value, long record) {
057        if (value < MIN) {
058          throw new IllegalArgumentException(
059              "Illagal value: " + NAME + " = " + value + " < MIN = " + MIN);
060        }
061        if (value > MAX) {
062          throw new IllegalArgumentException(
063              "Illagal value: " + NAME + " = " + value + " > MAX = " + MAX);
064        }
065        return (record & ~MASK) | (value << OFFSET);
066      }
067    }