Android Open Source - JiangHomeStyle_Android_Phone Zip Eight Byte Integer

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License

The source code is released under:

Apache License

Java Source Code

/*
 *  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
 */*from   w w  w .  jav a2s .  co m*/
 *      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.tools.zip;

import java.math.BigInteger;

import static org.apache.tools.zip.ZipConstants.BYTE_MASK;

/**
 * Utility class that represents an eight byte integer with conversion rules for
 * the big endian byte order of ZIP files.
 */
public final class ZipEightByteInteger
{

  private static final int BYTE_1 = 1;
  private static final int BYTE_1_MASK = 0xFF00;
  private static final int BYTE_1_SHIFT = 8;

  private static final int BYTE_2 = 2;
  private static final int BYTE_2_MASK = 0xFF0000;
  private static final int BYTE_2_SHIFT = 16;

  private static final int BYTE_3 = 3;
  private static final long BYTE_3_MASK = 0xFF000000L;
  private static final int BYTE_3_SHIFT = 24;

  private static final int BYTE_4 = 4;
  private static final long BYTE_4_MASK = 0xFF00000000L;
  private static final int BYTE_4_SHIFT = 32;

  private static final int BYTE_5 = 5;
  private static final long BYTE_5_MASK = 0xFF0000000000L;
  private static final int BYTE_5_SHIFT = 40;

  private static final int BYTE_6 = 6;
  private static final long BYTE_6_MASK = 0xFF000000000000L;
  private static final int BYTE_6_SHIFT = 48;

  private static final int BYTE_7 = 7;
  private static final long BYTE_7_MASK = 0x7F00000000000000L;
  private static final int BYTE_7_SHIFT = 56;

  private static final int LEFTMOST_BIT_SHIFT = 63;
  private static final byte LEFTMOST_BIT = (byte) 0x80;

  private final BigInteger value;

  public static final ZipEightByteInteger ZERO = new ZipEightByteInteger(0);

  /**
   * Create instance from a number.
   * 
   * @param value
   *            the long to store as a ZipEightByteInteger
   */
  public ZipEightByteInteger(long value)
  {
    this(BigInteger.valueOf(value));
  }

  /**
   * Create instance from a number.
   * 
   * @param value
   *            the BigInteger to store as a ZipEightByteInteger
   */
  public ZipEightByteInteger(BigInteger value)
  {
    this.value = value;
  }

  /**
   * Create instance from bytes.
   * 
   * @param bytes
   *            the bytes to store as a ZipEightByteInteger
   */
  public ZipEightByteInteger(byte[] bytes)
  {
    this(bytes, 0);
  }

  /**
   * Create instance from the eight bytes starting at offset.
   * 
   * @param bytes
   *            the bytes to store as a ZipEightByteInteger
   * @param offset
   *            the offset to start
   */
  public ZipEightByteInteger(byte[] bytes, int offset)
  {
    value = ZipEightByteInteger.getValue(bytes, offset);
  }

  /**
   * Get value as eight bytes in big endian byte order.
   * 
   * @return value as eight bytes in big endian order
   */
  public byte[] getBytes()
  {
    return ZipEightByteInteger.getBytes(value);
  }

  /**
   * Get value as Java long.
   * 
   * @return value as a long
   */
  public long getLongValue()
  {
    return value.longValue();
  }

  /**
   * Get value as Java long.
   * 
   * @return value as a long
   */
  public BigInteger getValue()
  {
    return value;
  }

  /**
   * Get value as eight bytes in big endian byte order.
   * 
   * @param value
   *            the value to convert
   * @return value as eight bytes in big endian byte order
   */
  public static byte[] getBytes(long value)
  {
    return getBytes(BigInteger.valueOf(value));
  }

  /**
   * Get value as eight bytes in big endian byte order.
   * 
   * @param value
   *            the value to convert
   * @return value as eight bytes in big endian byte order
   */
  public static byte[] getBytes(BigInteger value)
  {
    byte[] result = new byte[8];
    long val = value.longValue();
    result[0] = (byte) ((val & BYTE_MASK));
    result[BYTE_1] = (byte) ((val & BYTE_1_MASK) >> BYTE_1_SHIFT);
    result[BYTE_2] = (byte) ((val & BYTE_2_MASK) >> BYTE_2_SHIFT);
    result[BYTE_3] = (byte) ((val & BYTE_3_MASK) >> BYTE_3_SHIFT);
    result[BYTE_4] = (byte) ((val & BYTE_4_MASK) >> BYTE_4_SHIFT);
    result[BYTE_5] = (byte) ((val & BYTE_5_MASK) >> BYTE_5_SHIFT);
    result[BYTE_6] = (byte) ((val & BYTE_6_MASK) >> BYTE_6_SHIFT);
    result[BYTE_7] = (byte) ((val & BYTE_7_MASK) >> BYTE_7_SHIFT);
    if (value.testBit(LEFTMOST_BIT_SHIFT))
    {
      result[BYTE_7] |= LEFTMOST_BIT;
    }
    return result;
  }

  /**
   * Helper method to get the value as a Java long from eight bytes starting
   * at given array offset
   * 
   * @param bytes
   *            the array of bytes
   * @param offset
   *            the offset to start
   * @return the corresponding Java long value
   */
  public static long getLongValue(byte[] bytes, int offset)
  {
    return getValue(bytes, offset).longValue();
  }

  /**
   * Helper method to get the value as a Java BigInteger from eight bytes
   * starting at given array offset
   * 
   * @param bytes
   *            the array of bytes
   * @param offset
   *            the offset to start
   * @return the corresponding Java BigInteger value
   */
  public static BigInteger getValue(byte[] bytes, int offset)
  {
    long value = ((long) bytes[offset + BYTE_7] << BYTE_7_SHIFT) & BYTE_7_MASK;
    value += ((long) bytes[offset + BYTE_6] << BYTE_6_SHIFT) & BYTE_6_MASK;
    value += ((long) bytes[offset + BYTE_5] << BYTE_5_SHIFT) & BYTE_5_MASK;
    value += ((long) bytes[offset + BYTE_4] << BYTE_4_SHIFT) & BYTE_4_MASK;
    value += ((long) bytes[offset + BYTE_3] << BYTE_3_SHIFT) & BYTE_3_MASK;
    value += ((long) bytes[offset + BYTE_2] << BYTE_2_SHIFT) & BYTE_2_MASK;
    value += ((long) bytes[offset + BYTE_1] << BYTE_1_SHIFT) & BYTE_1_MASK;
    value += ((long) bytes[offset] & BYTE_MASK);
    BigInteger val = BigInteger.valueOf(value);
    return (bytes[offset + BYTE_7] & LEFTMOST_BIT) == LEFTMOST_BIT ? val.setBit(LEFTMOST_BIT_SHIFT) : val;
  }

  /**
   * Helper method to get the value as a Java long from an eight-byte array
   * 
   * @param bytes
   *            the array of bytes
   * @return the corresponding Java long value
   */
  public static long getLongValue(byte[] bytes)
  {
    return getLongValue(bytes, 0);
  }

  /**
   * Helper method to get the value as a Java long from an eight-byte array
   * 
   * @param bytes
   *            the array of bytes
   * @return the corresponding Java BigInteger value
   */
  public static BigInteger getValue(byte[] bytes)
  {
    return getValue(bytes, 0);
  }

  /**
   * Override to make two instances with same value equal.
   * 
   * @param o
   *            an object to compare
   * @return true if the objects are equal
   */
  @Override
  public boolean equals(Object o)
  {
    if (o == null || !(o instanceof ZipEightByteInteger))
    {
      return false;
    }
    return value.equals(((ZipEightByteInteger) o).getValue());
  }

  /**
   * Override to make two instances with same value equal.
   * 
   * @return the hashCode of the value stored in the ZipEightByteInteger
   */
  @Override
  public int hashCode()
  {
    return value.hashCode();
  }

  @Override
  public String toString()
  {
    return "ZipEightByteInteger value: " + value;
  }
}

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