Java example source code file (CompressedStream.java)

This example Java source code file (CompressedStream.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

address, compressedstream, logbitsperbyte, max_i

The CompressedStream.java Java example source code

/*
 * Copyright (c) 2000, 2005, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 *
 */

package sun.jvm.hotspot.code;

import sun.jvm.hotspot.debugger.*;

/** NOTE that this class takes the address of a buffer. This means
    that it can read previously-generated debug information directly
    from the target VM. However, it also means that you can't create a
    "wrapper" object for a CompressedStream down in the VM. It looks
    like these are only kept persistently in OopMaps, and the code has
    been special-cased in OopMap.java to handle this. */

public class CompressedStream {
  protected Address buffer;
  protected int     position;

  /** Equivalent to CompressedStream(buffer, 0) */
  public CompressedStream(Address buffer) {
    this(buffer, 0);
  }

  public CompressedStream(Address buffer, int position) {
    this.buffer   = buffer;
    this.position = position;
  }

  public Address getBuffer() {
    return buffer;
  }

  public static final int LogBitsPerByte = 3;
  public static final int BitsPerByte = 1 << 3;

  // Constants for UNSIGNED5 coding of Pack200
  public static final int lg_H = 6;
  public static final int H = 1< 31);
  }

  public int decodeSign(int value) {
    return (value >>> 1) ^ -(value & 1);
  }

  // 32-bit self-inverse encoding of float bits
  // converts trailing zeros (common in floats) to leading zeros
  public int reverseInt(int i) {
    // Hacker's Delight, Figure 7-1
    i = (i & 0x55555555) << 1 | (i >>> 1) & 0x55555555;
    i = (i & 0x33333333) << 3 | (i >>> 2) & 0x33333333;
    i = (i & 0x0f0f0f0f) << 4 | (i >>> 4) & 0x0f0f0f0f;
    i = (i << 24) | ((i & 0xff00) << 8) | ((i >>> 8) & 0xff00) | (i >>> 24);
    return i;
  }
}