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annotate dwt/internal/image/PngLzBlockReader.d @ 0:380af2bdd8e5

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Upload of whole dwt tree
author Jacob Carlborg <doob@me.com> <jacob.carlborg@gmail.com>
date Sat, 09 Aug 2008 17:00:02 +0200
parents
children 1a8b3cb347e0
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1 /*******************************************************************************
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2 * Copyright (c) 2000, 2006 IBM Corporation and others.
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3 * All rights reserved. This program and the accompanying materials
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4 * are made available under the terms of the Eclipse Public License v1.0
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5 * which accompanies this distribution, and is available at
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6 * http://www.eclipse.org/legal/epl-v10.html
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7 *
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8 * Contributors:
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9 * IBM Corporation - initial API and implementation
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10 *******************************************************************************/
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11 module dwt.internal.image;
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12
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13 import java.io.IOException;
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14
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15 public class PngLzBlockReader {
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16 bool isLastBlock;
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17 byte compressionType;
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18 int uncompressedBytesRemaining;
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19 PngDecodingDataStream stream;
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20 PngHuffmanTables huffmanTables;
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21
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22 byte[] window;
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23 int windowIndex;
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24 int copyIndex;
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25 int copyBytesRemaining;
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26
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27 static final int UNCOMPRESSED = 0;
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28 static final int COMPRESSED_FIXED = 1;
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29 static final int COMPRESSED_DYNAMIC = 2;
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30
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31 static final int END_OF_COMPRESSED_BLOCK = 256;
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32 static final int FIRST_LENGTH_CODE = 257;
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33 static final int LAST_LENGTH_CODE = 285;
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34 static final int FIRST_DISTANCE_CODE = 1;
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35 static final int LAST_DISTANCE_CODE = 29;
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36 static final int FIRST_CODE_LENGTH_CODE = 4;
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37 static final int LAST_CODE_LENGTH_CODE = 19;
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38
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39 static final int[] lengthBases = {
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40 3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 15, 17, 19, 23, 27,
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41 31, 35, 43, 51, 59, 67, 83, 99, 115, 131, 163, 195, 227, 258
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42 } ;
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43 static final int[] extraLengthBits = {
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44 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2,
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45 3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 0,
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46 };
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47 static final int[] distanceBases = {
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48 1, 2, 3, 4, 5, 7, 9, 13, 17, 25, 33, 49, 65, 97, 129,
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49 193, 257, 385, 513, 769, 1025, 1537, 2049, 3073, 4097,
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50 6145, 8193, 12289, 16385, 24577,
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51 };
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52 static final int[] extraDistanceBits = {
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53 0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7,
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54 8, 8, 9, 9, 10, 10, 11, 11, 12, 12, 13, 13,
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55 };
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56
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57
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58 PngLzBlockReader(PngDecodingDataStream stream) {
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59 this.stream = stream;
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60 isLastBlock = false;
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61 }
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62
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63 void setWindowSize(int windowSize) {
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64 window = new byte[windowSize];
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65 }
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66
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67 void readNextBlockHeader() throws IOException {
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68 isLastBlock = stream.getNextIdatBit() !is 0;
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69 compressionType = (byte)(stream.getNextIdatBits(2) & 0xFF);
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70 if (compressionType > 2) stream.error();
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71
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72 if (compressionType is UNCOMPRESSED) {
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73 byte b1 = stream.getNextIdatByte();
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74 byte b2 = stream.getNextIdatByte();
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75 byte b3 = stream.getNextIdatByte();
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76 byte b4 = stream.getNextIdatByte();
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77 if (b1 !is ~b3 || b2 !is ~b4) stream.error();
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78 uncompressedBytesRemaining = (b1 & 0xFF) | ((b2 & 0xFF) << 8);
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79 } else if (compressionType is COMPRESSED_DYNAMIC) {
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80 huffmanTables = PngHuffmanTables.getDynamicTables(stream);
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81 } else {
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82 huffmanTables = PngHuffmanTables.getFixedTables();
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83 }
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84 }
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85
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86 byte getNextByte() throws IOException {
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87 if (compressionType is UNCOMPRESSED) {
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88 if (uncompressedBytesRemaining is 0) {
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89 readNextBlockHeader();
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90 return getNextByte();
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91 }
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92 uncompressedBytesRemaining--;
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93 return stream.getNextIdatByte();
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94 } else {
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95 byte value = getNextCompressedByte();
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96 if (value is END_OF_COMPRESSED_BLOCK) {
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97 if (isLastBlock) stream.error();
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98 readNextBlockHeader();
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99 return getNextByte();
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100 } else {
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101 return value;
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102 }
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103 }
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104 }
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105
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106 private void assertBlockAtEnd() throws IOException {
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107 if (compressionType is UNCOMPRESSED) {
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108 if (uncompressedBytesRemaining > 0) stream.error();
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109 } else if (copyBytesRemaining > 0 ||
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110 (huffmanTables.getNextLiteralValue(stream) !is END_OF_COMPRESSED_BLOCK))
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111 {
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112 stream.error();
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113 }
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114 }
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115 void assertCompressedDataAtEnd() throws IOException {
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116 assertBlockAtEnd();
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117 while (!isLastBlock) {
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118 readNextBlockHeader();
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119 assertBlockAtEnd();
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120 }
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121 }
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122
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123 private byte getNextCompressedByte() throws IOException {
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124 if (copyBytesRemaining > 0) {
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125 byte value = window[copyIndex];
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126 window[windowIndex] = value;
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127 copyBytesRemaining--;
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128
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129 copyIndex++;
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130 windowIndex++;
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131 if (copyIndex is window.length) copyIndex = 0;
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132 if (windowIndex is window.length) windowIndex = 0;
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133
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134 return value;
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135 }
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136
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137 int value = huffmanTables.getNextLiteralValue(stream);
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138 if (value < END_OF_COMPRESSED_BLOCK) {
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139 window[windowIndex] = (byte) (value & 0xFF);
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140 windowIndex++;
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141 if (windowIndex >= window.length) windowIndex = 0;
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142 return (byte) (value & 0xFF);
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143 } else if (value is END_OF_COMPRESSED_BLOCK) {
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144 readNextBlockHeader();
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145 return getNextByte();
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146 } else if (value <= LAST_LENGTH_CODE) {
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147 int extraBits = extraLengthBits[value - FIRST_LENGTH_CODE];
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148 int length = lengthBases[value - FIRST_LENGTH_CODE];
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149 if (extraBits > 0) {
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150 length += stream.getNextIdatBits(extraBits);
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151 }
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152
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153 value = huffmanTables.getNextDistanceValue(stream);
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parents:
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154 if (value > LAST_DISTANCE_CODE) stream.error();
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155 extraBits = extraDistanceBits[value];
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156 int distance = distanceBases[value];
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157 if (extraBits > 0) {
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158 distance += stream.getNextIdatBits(extraBits);
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159 }
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160
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Jacob Carlborg <doob@me.com> <jacob.carlborg@gmail.com>
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161 copyIndex = windowIndex - distance;
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Jacob Carlborg <doob@me.com> <jacob.carlborg@gmail.com>
parents:
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162 if (copyIndex < 0) copyIndex += window.length;
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163
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164 copyBytesRemaining = length;
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165 return getNextCompressedByte();
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Jacob Carlborg <doob@me.com> <jacob.carlborg@gmail.com>
parents:
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166 } else {
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167 stream.error();
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Jacob Carlborg <doob@me.com> <jacob.carlborg@gmail.com>
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168 return 0;
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169 }
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parents:
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170 }
380af2bdd8e5 Upload of whole dwt tree
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parents:
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171
380af2bdd8e5 Upload of whole dwt tree
Jacob Carlborg <doob@me.com> <jacob.carlborg@gmail.com>
parents:
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172 }