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1 /*
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2 * Copyright 2000-2005 Sun Microsystems, Inc. All Rights Reserved.
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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4 *
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5 * This code is free software; you can redistribute it and/or modify it
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6 * under the terms of the GNU General Public License version 2 only, as
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7 * published by the Free Software Foundation.
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8 *
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9 * This code is distributed in the hope that it will be useful, but WITHOUT
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10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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12 * version 2 for more details (a copy is included in the LICENSE file that
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13 * accompanied this code).
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14 *
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15 * You should have received a copy of the GNU General Public License version
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16 * 2 along with this work; if not, write to the Free Software Foundation,
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17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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18 *
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19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
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20 * CA 95054 USA or visit www.sun.com if you need additional information or
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21 * have any questions.
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22 *
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23 */
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24
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25 package sun.jvm.hotspot.code;
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26
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27 import sun.jvm.hotspot.debugger.*;
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28
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29 public class CompressedReadStream extends CompressedStream {
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30 /** Equivalent to CompressedReadStream(buffer, 0) */
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31 public CompressedReadStream(Address buffer) {
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32 this(buffer, 0);
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33 }
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34
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35 public CompressedReadStream(Address buffer, int position) {
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36 super(buffer, position);
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37 }
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38
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39 public boolean readBoolean() {
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40 return (read() != 0);
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41 }
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42
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43 public byte readByte() {
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44 return (byte) read();
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45 }
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46
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47 public char readChar() {
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48 return (char) readInt();
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49 }
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50
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51 public short readShort() {
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52 return (short) readSignedInt();
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53 }
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54
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55 public int readSignedInt() {
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56 return decodeSign(readInt());
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57 }
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58
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59 public int readInt() {
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60 int b0 = read();
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61 if (b0 < L) {
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62 return b0;
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63 } else {
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64 return readIntMb(b0);
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65 }
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66 }
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67
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68
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69 public float readFloat() {
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70 return Float.intBitsToFloat(reverseInt(readInt()));
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71 }
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72
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73 public double readDouble() {
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74 int rh = readInt();
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75 int rl = readInt();
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76 int h = reverseInt(rh);
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77 int l = reverseInt(rl);
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78 return Double.longBitsToDouble((h << 32) | ((long)l & 0x00000000FFFFFFFFL));
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79 }
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80
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81 public long readLong() {
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82 long low = readSignedInt() & 0x00000000FFFFFFFFL;
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83 long high = readSignedInt();
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84 return (high << 32) | low;
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85 }
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86
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87 //--------------------------------------------------------------------------------
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88 // Internals only below this point
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89 //
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90
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91
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92 // This encoding, called UNSIGNED5, is taken from J2SE Pack200.
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93 // It assumes that most values have lots of leading zeroes.
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94 // Very small values, in the range [0..191], code in one byte.
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95 // Any 32-bit value (including negatives) can be coded, in
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96 // up to five bytes. The grammar is:
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97 // low_byte = [0..191]
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98 // high_byte = [192..255]
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99 // any_byte = low_byte | high_byte
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100 // coding = low_byte
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101 // | high_byte low_byte
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102 // | high_byte high_byte low_byte
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103 // | high_byte high_byte high_byte low_byte
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104 // | high_byte high_byte high_byte high_byte any_byte
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105 // Each high_byte contributes six bits of payload.
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106 // The encoding is one-to-one (except for integer overflow)
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107 // and easy to parse and unparse.
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108
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109 private int readIntMb(int b0) {
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110 int pos = position - 1;
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111 int sum = b0;
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112 // must collect more bytes: b[1]...b[4]
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113 int lg_H_i = lg_H;
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114 for (int i = 0; ;) {
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115 int b_i = read(pos + (++i));
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116 sum += b_i << lg_H_i; // sum += b[i]*(64**i)
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117 if (b_i < L || i == MAX_i) {
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118 setPosition(pos+i+1);
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119 return sum;
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120 }
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121 lg_H_i += lg_H;
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122 }
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123 }
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124
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125 private short read(int index) {
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126 return (short) buffer.getCIntegerAt(index, 1, true);
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127 }
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128
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129 /** Reads an unsigned byte, but returns it as a short */
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130 private short read() {
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131 short retval = (short) buffer.getCIntegerAt(position, 1, true);
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132 ++position;
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133 return retval;
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134 }
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135 }
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