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

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author duke
date Sat, 01 Dec 2007 00:00:00 +0000
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-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 public class CompressedReadStream extends CompressedStream {
30 /** Equivalent to CompressedReadStream(buffer, 0) */
31 public CompressedReadStream(Address buffer) {
32 this(buffer, 0);
33 }
34
35 public CompressedReadStream(Address buffer, int position) {
36 super(buffer, position);
37 }
38
39 public boolean readBoolean() {
40 return (read() != 0);
41 }
42
43 public byte readByte() {
44 return (byte) read();
45 }
46
47 public char readChar() {
48 return (char) readInt();
49 }
50
51 public short readShort() {
52 return (short) readSignedInt();
53 }
54
55 public int readSignedInt() {
56 return decodeSign(readInt());
57 }
58
59 public int readInt() {
60 int b0 = read();
61 if (b0 < L) {
62 return b0;
63 } else {
64 return readIntMb(b0);
65 }
66 }
67
68
69 public float readFloat() {
70 return Float.intBitsToFloat(reverseInt(readInt()));
71 }
72
73 public double readDouble() {
74 int rh = readInt();
75 int rl = readInt();
76 int h = reverseInt(rh);
77 int l = reverseInt(rl);
78 return Double.longBitsToDouble((h << 32) | ((long)l & 0x00000000FFFFFFFFL));
79 }
80
81 public long readLong() {
82 long low = readSignedInt() & 0x00000000FFFFFFFFL;
83 long high = readSignedInt();
84 return (high << 32) | low;
85 }
86
87 //--------------------------------------------------------------------------------
88 // Internals only below this point
89 //
90
91
92 // This encoding, called UNSIGNED5, is taken from J2SE Pack200.
93 // It assumes that most values have lots of leading zeroes.
94 // Very small values, in the range [0..191], code in one byte.
95 // Any 32-bit value (including negatives) can be coded, in
96 // up to five bytes. The grammar is:
97 // low_byte = [0..191]
98 // high_byte = [192..255]
99 // any_byte = low_byte | high_byte
100 // coding = low_byte
101 // | high_byte low_byte
102 // | high_byte high_byte low_byte
103 // | high_byte high_byte high_byte low_byte
104 // | high_byte high_byte high_byte high_byte any_byte
105 // Each high_byte contributes six bits of payload.
106 // The encoding is one-to-one (except for integer overflow)
107 // and easy to parse and unparse.
108
109 private int readIntMb(int b0) {
110 int pos = position - 1;
111 int sum = b0;
112 // must collect more bytes: b[1]...b[4]
113 int lg_H_i = lg_H;
114 for (int i = 0; ;) {
115 int b_i = read(pos + (++i));
116 sum += b_i << lg_H_i; // sum += b[i]*(64**i)
117 if (b_i < L || i == MAX_i) {
118 setPosition(pos+i+1);
119 return sum;
120 }
121 lg_H_i += lg_H;
122 }
123 }
124
125 private short read(int index) {
126 return (short) buffer.getCIntegerAt(index, 1, true);
127 }
128
129 /** Reads an unsigned byte, but returns it as a short */
130 private short read() {
131 short retval = (short) buffer.getCIntegerAt(position, 1, true);
132 ++position;
133 return retval;
134 }
135 }