Mercurial > hg > truffle

comparison agent/src/share/classes/sun/jvm/hotspot/code/CompressedStream.java @ 0:a61af66fc99e jdk7-b24

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
Initial load
author duke
date Sat, 01 Dec 2007 00:00:00 +0000
parents
children c18cbe5936b8
comparison
equal deleted inserted replaced
-1:000000000000 0:a61af66fc99e
1 /*
2 * Copyright 2000-2005 Sun Microsystems, Inc. All Rights Reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
20 * CA 95054 USA or visit www.sun.com if you need additional information or
21 * have any questions.
22 *
23 */
24
25 package sun.jvm.hotspot.code;
26
27 import sun.jvm.hotspot.debugger.*;
28
29 /** NOTE that this class takes the address of a buffer. This means
30 that it can read previously-generated debug information directly
31 from the target VM. However, it also means that you can't create a
32 "wrapper" object for a CompressedStream down in the VM. It looks
33 like these are only kept persistently in OopMaps, and the code has
34 been special-cased in OopMap.java to handle this. */
35
36 public class CompressedStream {
37 protected Address buffer;
38 protected int position;
39
40 /** Equivalent to CompressedStream(buffer, 0) */
41 public CompressedStream(Address buffer) {
42 this(buffer, 0);
43 }
44
45 public CompressedStream(Address buffer, int position) {
46 this.buffer = buffer;
47 this.position = position;
48 }
49
50 public Address getBuffer() {
51 return buffer;
52 }
53
54 public static final int LogBitsPerByte = 3;
55 public static final int BitsPerByte = 1 << 3;
56
57 // Constants for UNSIGNED5 coding of Pack200
58 public static final int lg_H = 6;
59 public static final int H = 1<<lg_H; // number of high codes (64)
60 public static final int L = (1<<BitsPerByte) - H; // number of low codes (192)
61 public static final int MAX_i = 4; // bytes are numbered in (0..4)
62
63 // Positioning
64 public int getPosition() {
65 return position;
66 }
67 public void setPosition(int position) {
68 this.position = position;
69 }
70
71 // 32-bit one-to-one sign encoding taken from Pack200
72 // converts leading sign bits into leading zeros with trailing sign bit
73 public int encodeSign(int value) {
74 return (value << 1) ^ (value >> 31);
75 }
76
77 public int decodeSign(int value) {
78 return (value >>> 1) ^ -(value & 1);
79 }
80
81 // 32-bit self-inverse encoding of float bits
82 // converts trailing zeros (common in floats) to leading zeros
83 public int reverseInt(int i) {
84 // Hacker's Delight, Figure 7-1
85 i = (i & 0x55555555) << 1 | (i >>> 1) & 0x55555555;
86 i = (i & 0x33333333) << 3 | (i >>> 2) & 0x33333333;
87 i = (i & 0x0f0f0f0f) << 4 | (i >>> 4) & 0x0f0f0f0f;
88 i = (i << 24) | ((i & 0xff00) << 8) | ((i >>> 8) & 0xff00) | (i >>> 24);
89 return i;
90 }
91 }