content: /*
   *  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 com.alimama.mdrill.utils.zip;
  
  import java.math.BigInteger;
  
  import static com.alimama.mdrill.utils.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;
      }
  }
  