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 */
018package org.apache.hadoop.hdfs.util;
019
020import java.io.Serializable;
021
022
023/**
024 * Bit format in a long.
025 */
026public 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  
068  public long getMin() {
069    return MIN;
070  }
071}