content: /*
   * Copyright (C) 2007 The Android Open Source Project
   *
   * Licensed 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.
   */
  
  /*
   * As per the Apache license requirements, this file has been modified
   * from its original state.
   *
   * Such modifications are Copyright (C) 2010 Ben Gruver, and are released
   * under the original license
   */
  
  package org.jf.dexlib.Util;
  
  /**
   * Wrapper for a <code>byte[]</code>, which provides read-only access and
   * can "reveal" a partial slice of the underlying array.
   *
   * <b>Note:</b> Multibyte accessors all use big-endian order.
   */
  public final class ByteArray {
      /** non-null; underlying array */
      private final byte[] bytes;
  
      /** <code>&gt;= 0</code>; start index of the slice (inclusive) */
      private final int start;
  
      /** <code>&gt;= 0, &lt;= bytes.length</code>; size computed as
       * <code>end - start</code> (in the constructor) */
      private final int size;
  
      /**
       * Constructs an instance.
       *
       * @param bytes non-null; the underlying array
       * @param start <code>&gt;= 0</code>; start index of the slice (inclusive)
       * @param end <code>&gt;= start, &lt;= bytes.length</code>; end index of
       * the slice (exclusive)
       */
      public ByteArray(byte[] bytes, int start, int end) {
          if (bytes == null) {
              throw new NullPointerException("bytes == null");
          }
  
          if (start < 0) {
              throw new IllegalArgumentException("start < 0");
          }
  
          if (end < start) {
              throw new IllegalArgumentException("end < start");
          }
  
          if (end > bytes.length) {
              throw new IllegalArgumentException("end > bytes.length");
          }
  
          this.bytes = bytes;
          this.start = start;
          this.size = end - start;
      }
  
      /**
       * Constructs an instance from an entire <code>byte[]</code>.
       *
       * @param bytes non-null; the underlying array
       */
      public ByteArray(byte[] bytes) {
          this(bytes, 0, bytes.length);
      }
  
      /**
       * Gets the size of the array, in bytes.
       *
       * @return &gt;= 0; the size
       */
      public int size() {
          return size;
      }
  
      /**
       * Returns a slice (that is, a sub-array) of this instance.
       *
       * @param start <code>&gt;= 0</code>; start index of the slice (inclusive)
       * @param end <code>&gt;= start, &lt;= size()</code>; end index of
       * the slice (exclusive)
       * @return non-null; the slice
       */
      public ByteArray slice(int start, int end) {
          checkOffsets(start, end);
          return new ByteArray(bytes, start + this.start, end + this.start);
      }
  
      /**
       * Returns the offset into the given array represented by the given
       * offset into this instance.
       *
       * @param offset offset into this instance
       * @param bytes non-null; (alleged) underlying array
       * @return corresponding offset into <code>bytes</code>
       * @throws IllegalArgumentException thrown if <code>bytes</code> is
       * not the underlying array of this instance
       */
      public int underlyingOffset(int offset, byte[] bytes) {
          if (bytes != this.bytes) {
              throw new IllegalArgumentException("wrong bytes");
          }
  
          return start + offset;
      }
  
      /**
       * Gets the <code>signed byte</code> value at a particular offset.
       *
       * @param off <code>&gt;= 0, &lt; size(); offset to fetch
       * @return <code>signed byte</code> at that offset
       */
      public int getByte(int off) {
          checkOffsets(off, off + 1);
          return getByte0(off);
      }
  
      /**
       * Gets the <code>signed short</code> value at a particular offset.
       *
       * @param off <code>&gt;= 0, &lt; (size() - 1); offset to fetch
       * @return <code>signed short</code> at that offset
       */
      public int getShort(int off) {
          checkOffsets(off, off + 2);
          return (getByte0(off) << 8) | getUnsignedByte0(off + 1);
      }
  
      /**
       * Gets the <code>signed int</code> value at a particular offset.
       *
       * @param off <code>&gt;= 0, &lt; (size() - 3); offset to fetch
       * @return <code>signed int</code> at that offset
       */
      public int getInt(int off) {
          checkOffsets(off, off + 4);
          return (getByte0(off) << 24) |
              (getUnsignedByte0(off + 1) << 16) |
              (getUnsignedByte0(off + 2) << 8) |
              getUnsignedByte0(off + 3);
      }
  
      /**
       * Gets the <code>signed long</code> value at a particular offset.
       *
       * @param off <code>&gt;= 0, &lt; (size() - 7); offset to fetch
       * @return <code>signed int</code> at that offset
       */
      public long getLong(int off) {
          checkOffsets(off, off + 8);
          int part1 = (getByte0(off) << 24) |
              (getUnsignedByte0(off + 1) << 16) |
              (getUnsignedByte0(off + 2) << 8) |
              getUnsignedByte0(off + 3);
          int part2 = (getByte0(off + 4) << 24) |
              (getUnsignedByte0(off + 5) << 16) |
              (getUnsignedByte0(off + 6) << 8) |
              getUnsignedByte0(off + 7);
  
          return (part2 & 0xffffffffL) | ((long) part1) << 32;
      }
  
      /**
       * Gets the <code>unsigned byte</code> value at a particular offset.
       *
       * @param off <code>&gt;= 0, &lt; size(); offset to fetch
       * @return <code>unsigned byte</code> at that offset
       */
      public int getUnsignedByte(int off) {
          checkOffsets(off, off + 1);
          return getUnsignedByte0(off);
      }
  
      /**
       * Gets the <code>unsigned short</code> value at a particular offset.
       *
       * @param off <code>&gt;= 0, &lt; (size() - 1); offset to fetch
       * @return <code>unsigned short</code> at that offset
       */
      public int getUnsignedShort(int off) {
          checkOffsets(off, off + 2);
          return (getUnsignedByte0(off) << 8) | getUnsignedByte0(off + 1);
      }
  
      /**
       * Copies the contents of this instance into the given raw
       * <code>byte[]</code> at the given offset. The given array must be
       * large enough.
       *
       * @param out non-null; array to hold the output
       * @param offset non-null; index into <code>out</code> for the first
       * byte of output
       */
      public void getBytes(byte[] out, int offset) {
          if ((out.length - offset) < size) {
              throw new IndexOutOfBoundsException("(out.length - offset) < " +
                                                  "size()");
          }
  
          System.arraycopy(bytes, start, out, offset, size);
      }
  
      /**
       * Checks a range of offsets for validity, throwing if invalid.
       *
       * @param s start offset (inclusive)
       * @param e end offset (exclusive)
       */
      private void checkOffsets(int s, int e) {
          if ((s < 0) || (e < s) || (e > size)) {
              throw new IllegalArgumentException("bad range: " + s + ".." + e +
                                                 "; actual size " + size);
          }
      }
  
      /**
       * Gets the <code>signed byte</code> value at the given offset,
       * without doing any argument checking.
       *
       * @param off offset to fetch
       * @return byte at that offset
       */
      private int getByte0(int off) {
          return bytes[start + off];
      }
  
      /**
       * Gets the <code>unsigned byte</code> value at the given offset,
       * without doing any argument checking.
       *
       * @param off offset to fetch
       * @return byte at that offset
       */
      private int getUnsignedByte0(int off) {
          return bytes[start + off] & 0xff;
      }
  }