/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.hadoop.hdfs.util;

import java.io.Serializable;


/**
 * Bit format in a long.
 */
public class LongBitFormat implements Serializable {
  private static final long serialVersionUID = 1L;

  public interface Enum {
    int getLength();
  }

  private final String NAME;
  /** Bit offset */
  private final int OFFSET;
  /** Bit length */
  private final int LENGTH;
  /** Minimum value */
  private final long MIN;
  /** Maximum value */
  private final long MAX;
  /** Bit mask */
  private final long MASK;

  public LongBitFormat(String name, LongBitFormat previous, int length,
                       long min) {
    NAME = name;
    OFFSET = previous == null? 0: previous.OFFSET + previous.LENGTH;
    LENGTH = length;
    MIN = min;
    MAX = ((-1L) >>> (64 - LENGTH));
    MASK = MAX << OFFSET;
  }

  /** Retrieve the value from the record. */
  public long retrieve(long record) {
    return (record & MASK) >>> OFFSET;
  }

  /** Combine the value to the record. */
  public long combine(long value, long record) {
    if (value < MIN) {
      throw new IllegalArgumentException(
          "Illagal value: " + NAME + " = " + value + " < MIN = " + MIN);
    }
    if (value > MAX) {
      throw new IllegalArgumentException(
          "Illagal value: " + NAME + " = " + value + " > MAX = " + MAX);
    }
    return (record & ~MASK) | (value << OFFSET);
  }

  public long getMin() {
    return MIN;
  }

  public int getLength() {
    return LENGTH;
  }
}
