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1 /* |
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2 * Copyright (c) 2018, Oracle and/or its affiliates. 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. Oracle designates this |
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8 * particular file as subject to the "Classpath" exception as provided |
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9 * by Oracle in the LICENSE file that accompanied this code. |
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10 * |
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11 * This code is distributed in the hope that it will be useful, but WITHOUT |
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12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
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14 * version 2 for more details (a copy is included in the LICENSE file that |
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15 * accompanied this code). |
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16 * |
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17 * You should have received a copy of the GNU General Public License version |
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18 * 2 along with this work; if not, write to the Free Software Foundation, |
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19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
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20 * |
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21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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22 * or visit www.oracle.com if you need additional information or have any |
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23 * questions. |
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24 */ |
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25 |
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26 package jdk.internal.net.http.hpack; |
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27 |
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28 import java.io.IOException; |
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29 import java.nio.ByteBuffer; |
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30 import java.util.List; |
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31 import java.util.Objects; |
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32 |
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33 public final class QuickHuffman { |
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34 |
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35 /* |
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36 * Huffman codes for encoding. |
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37 * |
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38 * EOS will never be matched, since there is no symbol for it, thus no need |
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39 * to store it in the array. Thus, the length of the array is 256, not 257. |
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40 * Code information for each character is encoded as follows: |
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41 * |
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42 * MSB LSB |
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43 * +----------------+----------------+ |
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44 * |~code | length~| |
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45 * +----------------+----------------+ |
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46 * |<----- 32 ----->|<----- 32 ----->| |
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47 * |<------------- 64 -------------->| |
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48 * |
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49 * The leftmost 32 bits hold the code value. This value is aligned left |
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50 * (or MSB). The rightmost 32 bits hold the length of the code value. |
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51 * This length is aligned right (or LSB). |
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52 */ |
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53 private static final long[] codes = new long[256]; |
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54 |
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55 private static long codeValueOf(char c) { |
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56 return codes[c] & 0xffffffff00000000L; |
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57 } |
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58 |
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59 private static long codeLengthOf(char c) { |
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60 return codes[c] & 0x00000000ffffffffL; |
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61 } |
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62 |
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63 private static final int EOS_LENGTH = 30; |
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64 private static final int EOS_LSB = 0x3fffffff; |
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65 private static final long EOS_MSB = EOS_LSB << (64 - EOS_LENGTH); |
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66 |
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67 /* |
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68 * Huffman codes for decoding. |
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69 * |
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70 * Root node contains 257 descendant nodes, including EOS. |
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71 */ |
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72 private static final Node root; |
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73 |
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74 static { |
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75 TemporaryNode tmpRoot = new TemporaryNode(); |
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76 addChar(tmpRoot, 0, 0x1ff8, 13); |
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77 addChar(tmpRoot, 1, 0x7fffd8, 23); |
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78 addChar(tmpRoot, 2, 0xfffffe2, 28); |
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79 addChar(tmpRoot, 3, 0xfffffe3, 28); |
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80 addChar(tmpRoot, 4, 0xfffffe4, 28); |
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81 addChar(tmpRoot, 5, 0xfffffe5, 28); |
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82 addChar(tmpRoot, 6, 0xfffffe6, 28); |
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83 addChar(tmpRoot, 7, 0xfffffe7, 28); |
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84 addChar(tmpRoot, 8, 0xfffffe8, 28); |
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85 addChar(tmpRoot, 9, 0xffffea, 24); |
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86 addChar(tmpRoot, 10, 0x3ffffffc, 30); |
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87 addChar(tmpRoot, 11, 0xfffffe9, 28); |
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88 addChar(tmpRoot, 12, 0xfffffea, 28); |
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89 addChar(tmpRoot, 13, 0x3ffffffd, 30); |
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90 addChar(tmpRoot, 14, 0xfffffeb, 28); |
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91 addChar(tmpRoot, 15, 0xfffffec, 28); |
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92 addChar(tmpRoot, 16, 0xfffffed, 28); |
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93 addChar(tmpRoot, 17, 0xfffffee, 28); |
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94 addChar(tmpRoot, 18, 0xfffffef, 28); |
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95 addChar(tmpRoot, 19, 0xffffff0, 28); |
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96 addChar(tmpRoot, 20, 0xffffff1, 28); |
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97 addChar(tmpRoot, 21, 0xffffff2, 28); |
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98 addChar(tmpRoot, 22, 0x3ffffffe, 30); |
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99 addChar(tmpRoot, 23, 0xffffff3, 28); |
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100 addChar(tmpRoot, 24, 0xffffff4, 28); |
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101 addChar(tmpRoot, 25, 0xffffff5, 28); |
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102 addChar(tmpRoot, 26, 0xffffff6, 28); |
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103 addChar(tmpRoot, 27, 0xffffff7, 28); |
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104 addChar(tmpRoot, 28, 0xffffff8, 28); |
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105 addChar(tmpRoot, 29, 0xffffff9, 28); |
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106 addChar(tmpRoot, 30, 0xffffffa, 28); |
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107 addChar(tmpRoot, 31, 0xffffffb, 28); |
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108 addChar(tmpRoot, 32, 0x14, 6); |
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109 addChar(tmpRoot, 33, 0x3f8, 10); |
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110 addChar(tmpRoot, 34, 0x3f9, 10); |
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111 addChar(tmpRoot, 35, 0xffa, 12); |
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112 addChar(tmpRoot, 36, 0x1ff9, 13); |
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113 addChar(tmpRoot, 37, 0x15, 6); |
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114 addChar(tmpRoot, 38, 0xf8, 8); |
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115 addChar(tmpRoot, 39, 0x7fa, 11); |
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116 addChar(tmpRoot, 40, 0x3fa, 10); |
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117 addChar(tmpRoot, 41, 0x3fb, 10); |
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118 addChar(tmpRoot, 42, 0xf9, 8); |
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119 addChar(tmpRoot, 43, 0x7fb, 11); |
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120 addChar(tmpRoot, 44, 0xfa, 8); |
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121 addChar(tmpRoot, 45, 0x16, 6); |
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122 addChar(tmpRoot, 46, 0x17, 6); |
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123 addChar(tmpRoot, 47, 0x18, 6); |
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124 addChar(tmpRoot, 48, 0x0, 5); |
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125 addChar(tmpRoot, 49, 0x1, 5); |
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126 addChar(tmpRoot, 50, 0x2, 5); |
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127 addChar(tmpRoot, 51, 0x19, 6); |
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128 addChar(tmpRoot, 52, 0x1a, 6); |
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129 addChar(tmpRoot, 53, 0x1b, 6); |
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130 addChar(tmpRoot, 54, 0x1c, 6); |
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131 addChar(tmpRoot, 55, 0x1d, 6); |
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132 addChar(tmpRoot, 56, 0x1e, 6); |
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133 addChar(tmpRoot, 57, 0x1f, 6); |
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134 addChar(tmpRoot, 58, 0x5c, 7); |
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135 addChar(tmpRoot, 59, 0xfb, 8); |
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136 addChar(tmpRoot, 60, 0x7ffc, 15); |
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137 addChar(tmpRoot, 61, 0x20, 6); |
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138 addChar(tmpRoot, 62, 0xffb, 12); |
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139 addChar(tmpRoot, 63, 0x3fc, 10); |
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140 addChar(tmpRoot, 64, 0x1ffa, 13); |
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141 addChar(tmpRoot, 65, 0x21, 6); |
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142 addChar(tmpRoot, 66, 0x5d, 7); |
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143 addChar(tmpRoot, 67, 0x5e, 7); |
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144 addChar(tmpRoot, 68, 0x5f, 7); |
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145 addChar(tmpRoot, 69, 0x60, 7); |
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146 addChar(tmpRoot, 70, 0x61, 7); |
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147 addChar(tmpRoot, 71, 0x62, 7); |
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148 addChar(tmpRoot, 72, 0x63, 7); |
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149 addChar(tmpRoot, 73, 0x64, 7); |
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150 addChar(tmpRoot, 74, 0x65, 7); |
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151 addChar(tmpRoot, 75, 0x66, 7); |
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152 addChar(tmpRoot, 76, 0x67, 7); |
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153 addChar(tmpRoot, 77, 0x68, 7); |
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154 addChar(tmpRoot, 78, 0x69, 7); |
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155 addChar(tmpRoot, 79, 0x6a, 7); |
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156 addChar(tmpRoot, 80, 0x6b, 7); |
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157 addChar(tmpRoot, 81, 0x6c, 7); |
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158 addChar(tmpRoot, 82, 0x6d, 7); |
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159 addChar(tmpRoot, 83, 0x6e, 7); |
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160 addChar(tmpRoot, 84, 0x6f, 7); |
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161 addChar(tmpRoot, 85, 0x70, 7); |
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162 addChar(tmpRoot, 86, 0x71, 7); |
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163 addChar(tmpRoot, 87, 0x72, 7); |
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164 addChar(tmpRoot, 88, 0xfc, 8); |
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165 addChar(tmpRoot, 89, 0x73, 7); |
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166 addChar(tmpRoot, 90, 0xfd, 8); |
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167 addChar(tmpRoot, 91, 0x1ffb, 13); |
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168 addChar(tmpRoot, 92, 0x7fff0, 19); |
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169 addChar(tmpRoot, 93, 0x1ffc, 13); |
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170 addChar(tmpRoot, 94, 0x3ffc, 14); |
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171 addChar(tmpRoot, 95, 0x22, 6); |
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172 addChar(tmpRoot, 96, 0x7ffd, 15); |
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173 addChar(tmpRoot, 97, 0x3, 5); |
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174 addChar(tmpRoot, 98, 0x23, 6); |
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175 addChar(tmpRoot, 99, 0x4, 5); |
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176 addChar(tmpRoot, 100, 0x24, 6); |
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177 addChar(tmpRoot, 101, 0x5, 5); |
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178 addChar(tmpRoot, 102, 0x25, 6); |
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179 addChar(tmpRoot, 103, 0x26, 6); |
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180 addChar(tmpRoot, 104, 0x27, 6); |
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181 addChar(tmpRoot, 105, 0x6, 5); |
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182 addChar(tmpRoot, 106, 0x74, 7); |
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183 addChar(tmpRoot, 107, 0x75, 7); |
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184 addChar(tmpRoot, 108, 0x28, 6); |
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185 addChar(tmpRoot, 109, 0x29, 6); |
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186 addChar(tmpRoot, 110, 0x2a, 6); |
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187 addChar(tmpRoot, 111, 0x7, 5); |
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188 addChar(tmpRoot, 112, 0x2b, 6); |
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189 addChar(tmpRoot, 113, 0x76, 7); |
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190 addChar(tmpRoot, 114, 0x2c, 6); |
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191 addChar(tmpRoot, 115, 0x8, 5); |
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192 addChar(tmpRoot, 116, 0x9, 5); |
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193 addChar(tmpRoot, 117, 0x2d, 6); |
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194 addChar(tmpRoot, 118, 0x77, 7); |
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195 addChar(tmpRoot, 119, 0x78, 7); |
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196 addChar(tmpRoot, 120, 0x79, 7); |
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197 addChar(tmpRoot, 121, 0x7a, 7); |
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198 addChar(tmpRoot, 122, 0x7b, 7); |
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199 addChar(tmpRoot, 123, 0x7ffe, 15); |
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200 addChar(tmpRoot, 124, 0x7fc, 11); |
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201 addChar(tmpRoot, 125, 0x3ffd, 14); |
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202 addChar(tmpRoot, 126, 0x1ffd, 13); |
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203 addChar(tmpRoot, 127, 0xffffffc, 28); |
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204 addChar(tmpRoot, 128, 0xfffe6, 20); |
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205 addChar(tmpRoot, 129, 0x3fffd2, 22); |
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206 addChar(tmpRoot, 130, 0xfffe7, 20); |
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207 addChar(tmpRoot, 131, 0xfffe8, 20); |
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208 addChar(tmpRoot, 132, 0x3fffd3, 22); |
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209 addChar(tmpRoot, 133, 0x3fffd4, 22); |
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210 addChar(tmpRoot, 134, 0x3fffd5, 22); |
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211 addChar(tmpRoot, 135, 0x7fffd9, 23); |
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212 addChar(tmpRoot, 136, 0x3fffd6, 22); |
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213 addChar(tmpRoot, 137, 0x7fffda, 23); |
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214 addChar(tmpRoot, 138, 0x7fffdb, 23); |
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215 addChar(tmpRoot, 139, 0x7fffdc, 23); |
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216 addChar(tmpRoot, 140, 0x7fffdd, 23); |
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217 addChar(tmpRoot, 141, 0x7fffde, 23); |
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218 addChar(tmpRoot, 142, 0xffffeb, 24); |
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219 addChar(tmpRoot, 143, 0x7fffdf, 23); |
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220 addChar(tmpRoot, 144, 0xffffec, 24); |
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221 addChar(tmpRoot, 145, 0xffffed, 24); |
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222 addChar(tmpRoot, 146, 0x3fffd7, 22); |
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223 addChar(tmpRoot, 147, 0x7fffe0, 23); |
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224 addChar(tmpRoot, 148, 0xffffee, 24); |
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225 addChar(tmpRoot, 149, 0x7fffe1, 23); |
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226 addChar(tmpRoot, 150, 0x7fffe2, 23); |
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227 addChar(tmpRoot, 151, 0x7fffe3, 23); |
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228 addChar(tmpRoot, 152, 0x7fffe4, 23); |
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229 addChar(tmpRoot, 153, 0x1fffdc, 21); |
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230 addChar(tmpRoot, 154, 0x3fffd8, 22); |
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231 addChar(tmpRoot, 155, 0x7fffe5, 23); |
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232 addChar(tmpRoot, 156, 0x3fffd9, 22); |
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233 addChar(tmpRoot, 157, 0x7fffe6, 23); |
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234 addChar(tmpRoot, 158, 0x7fffe7, 23); |
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235 addChar(tmpRoot, 159, 0xffffef, 24); |
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236 addChar(tmpRoot, 160, 0x3fffda, 22); |
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237 addChar(tmpRoot, 161, 0x1fffdd, 21); |
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238 addChar(tmpRoot, 162, 0xfffe9, 20); |
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239 addChar(tmpRoot, 163, 0x3fffdb, 22); |
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240 addChar(tmpRoot, 164, 0x3fffdc, 22); |
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241 addChar(tmpRoot, 165, 0x7fffe8, 23); |
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242 addChar(tmpRoot, 166, 0x7fffe9, 23); |
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243 addChar(tmpRoot, 167, 0x1fffde, 21); |
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244 addChar(tmpRoot, 168, 0x7fffea, 23); |
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245 addChar(tmpRoot, 169, 0x3fffdd, 22); |
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246 addChar(tmpRoot, 170, 0x3fffde, 22); |
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247 addChar(tmpRoot, 171, 0xfffff0, 24); |
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248 addChar(tmpRoot, 172, 0x1fffdf, 21); |
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249 addChar(tmpRoot, 173, 0x3fffdf, 22); |
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250 addChar(tmpRoot, 174, 0x7fffeb, 23); |
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251 addChar(tmpRoot, 175, 0x7fffec, 23); |
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252 addChar(tmpRoot, 176, 0x1fffe0, 21); |
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253 addChar(tmpRoot, 177, 0x1fffe1, 21); |
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254 addChar(tmpRoot, 178, 0x3fffe0, 22); |
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255 addChar(tmpRoot, 179, 0x1fffe2, 21); |
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256 addChar(tmpRoot, 180, 0x7fffed, 23); |
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257 addChar(tmpRoot, 181, 0x3fffe1, 22); |
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258 addChar(tmpRoot, 182, 0x7fffee, 23); |
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259 addChar(tmpRoot, 183, 0x7fffef, 23); |
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260 addChar(tmpRoot, 184, 0xfffea, 20); |
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261 addChar(tmpRoot, 185, 0x3fffe2, 22); |
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262 addChar(tmpRoot, 186, 0x3fffe3, 22); |
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263 addChar(tmpRoot, 187, 0x3fffe4, 22); |
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264 addChar(tmpRoot, 188, 0x7ffff0, 23); |
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265 addChar(tmpRoot, 189, 0x3fffe5, 22); |
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266 addChar(tmpRoot, 190, 0x3fffe6, 22); |
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267 addChar(tmpRoot, 191, 0x7ffff1, 23); |
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268 addChar(tmpRoot, 192, 0x3ffffe0, 26); |
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269 addChar(tmpRoot, 193, 0x3ffffe1, 26); |
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270 addChar(tmpRoot, 194, 0xfffeb, 20); |
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271 addChar(tmpRoot, 195, 0x7fff1, 19); |
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272 addChar(tmpRoot, 196, 0x3fffe7, 22); |
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273 addChar(tmpRoot, 197, 0x7ffff2, 23); |
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274 addChar(tmpRoot, 198, 0x3fffe8, 22); |
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275 addChar(tmpRoot, 199, 0x1ffffec, 25); |
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276 addChar(tmpRoot, 200, 0x3ffffe2, 26); |
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277 addChar(tmpRoot, 201, 0x3ffffe3, 26); |
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278 addChar(tmpRoot, 202, 0x3ffffe4, 26); |
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279 addChar(tmpRoot, 203, 0x7ffffde, 27); |
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280 addChar(tmpRoot, 204, 0x7ffffdf, 27); |
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281 addChar(tmpRoot, 205, 0x3ffffe5, 26); |
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282 addChar(tmpRoot, 206, 0xfffff1, 24); |
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283 addChar(tmpRoot, 207, 0x1ffffed, 25); |
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284 addChar(tmpRoot, 208, 0x7fff2, 19); |
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285 addChar(tmpRoot, 209, 0x1fffe3, 21); |
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286 addChar(tmpRoot, 210, 0x3ffffe6, 26); |
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287 addChar(tmpRoot, 211, 0x7ffffe0, 27); |
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288 addChar(tmpRoot, 212, 0x7ffffe1, 27); |
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289 addChar(tmpRoot, 213, 0x3ffffe7, 26); |
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290 addChar(tmpRoot, 214, 0x7ffffe2, 27); |
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291 addChar(tmpRoot, 215, 0xfffff2, 24); |
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292 addChar(tmpRoot, 216, 0x1fffe4, 21); |
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293 addChar(tmpRoot, 217, 0x1fffe5, 21); |
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294 addChar(tmpRoot, 218, 0x3ffffe8, 26); |
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295 addChar(tmpRoot, 219, 0x3ffffe9, 26); |
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296 addChar(tmpRoot, 220, 0xffffffd, 28); |
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297 addChar(tmpRoot, 221, 0x7ffffe3, 27); |
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298 addChar(tmpRoot, 222, 0x7ffffe4, 27); |
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299 addChar(tmpRoot, 223, 0x7ffffe5, 27); |
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300 addChar(tmpRoot, 224, 0xfffec, 20); |
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301 addChar(tmpRoot, 225, 0xfffff3, 24); |
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302 addChar(tmpRoot, 226, 0xfffed, 20); |
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303 addChar(tmpRoot, 227, 0x1fffe6, 21); |
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304 addChar(tmpRoot, 228, 0x3fffe9, 22); |
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305 addChar(tmpRoot, 229, 0x1fffe7, 21); |
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306 addChar(tmpRoot, 230, 0x1fffe8, 21); |
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307 addChar(tmpRoot, 231, 0x7ffff3, 23); |
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308 addChar(tmpRoot, 232, 0x3fffea, 22); |
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309 addChar(tmpRoot, 233, 0x3fffeb, 22); |
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310 addChar(tmpRoot, 234, 0x1ffffee, 25); |
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311 addChar(tmpRoot, 235, 0x1ffffef, 25); |
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312 addChar(tmpRoot, 236, 0xfffff4, 24); |
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313 addChar(tmpRoot, 237, 0xfffff5, 24); |
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314 addChar(tmpRoot, 238, 0x3ffffea, 26); |
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315 addChar(tmpRoot, 239, 0x7ffff4, 23); |
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316 addChar(tmpRoot, 240, 0x3ffffeb, 26); |
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317 addChar(tmpRoot, 241, 0x7ffffe6, 27); |
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318 addChar(tmpRoot, 242, 0x3ffffec, 26); |
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319 addChar(tmpRoot, 243, 0x3ffffed, 26); |
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320 addChar(tmpRoot, 244, 0x7ffffe7, 27); |
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321 addChar(tmpRoot, 245, 0x7ffffe8, 27); |
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322 addChar(tmpRoot, 246, 0x7ffffe9, 27); |
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323 addChar(tmpRoot, 247, 0x7ffffea, 27); |
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324 addChar(tmpRoot, 248, 0x7ffffeb, 27); |
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325 addChar(tmpRoot, 249, 0xffffffe, 28); |
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326 addChar(tmpRoot, 250, 0x7ffffec, 27); |
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327 addChar(tmpRoot, 251, 0x7ffffed, 27); |
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328 addChar(tmpRoot, 252, 0x7ffffee, 27); |
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329 addChar(tmpRoot, 253, 0x7ffffef, 27); |
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330 addChar(tmpRoot, 254, 0x7fffff0, 27); |
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331 addChar(tmpRoot, 255, 0x3ffffee, 26); |
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332 addEOS (tmpRoot, 256, EOS_LSB, EOS_LENGTH); |
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333 |
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334 // The difference in performance can always be checked by not using |
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335 // the immutable trie: |
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336 // root = tmpRoot; |
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337 root = ImmutableNode.copyOf(tmpRoot); |
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338 } |
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339 |
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340 private QuickHuffman() { } |
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341 |
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342 private static void addChar(Node root, int symbol, int code, int bitLength) |
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343 { |
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344 addLeaf(root, (char) symbol, code, bitLength, false); |
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345 long value = ((long) code) << (64 - bitLength); // re-align MSB <- LSB |
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346 codes[symbol] = value | bitLength; |
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347 } |
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348 |
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349 private static void addEOS(Node root, int symbol, int code, int bitLength) |
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350 { |
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351 addLeaf(root, (char) symbol, code, bitLength, true); |
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352 } |
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353 |
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354 private static void addLeaf(Node root, |
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355 char symbol, |
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356 int code, |
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357 int bitLength, |
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358 boolean isEOS) |
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359 { |
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360 assert 0 < bitLength && bitLength <= 32 : bitLength; |
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361 Node curr = root; |
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362 int nBytes = bytesForBits(bitLength); |
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363 // The number of bits the code needs to be shifted to the left in order |
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364 // to align with the byte #nBytes boundary: |
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365 int align = (nBytes << 3) - bitLength; |
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366 code <<= align; |
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367 // descend the trie until the last element |
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368 int l = 0; |
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369 for (int i = 0, probe = 0xff << ((nBytes - 1) << 3); |
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370 i < nBytes - 1; |
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371 i++, probe >>>= 8) |
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372 { |
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373 curr.setEOSPath(curr.isEOSPath() | isEOS); |
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374 int idx = (code & probe) >>> ((nBytes - 1 - i) << 3); |
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375 curr = curr.getOrCreateChild(idx); |
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376 curr.setLength(8); |
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377 l += 8; |
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378 } |
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379 // Assign the same char to all byte variants. For example, if the code |
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380 // and its length are 00011b and 5 respectively (letter 'a') then, in |
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381 // order to be able to match any byte starting with 00011b prefix, |
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382 // the following nodes need to be created: |
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383 // |
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384 // 00011000b, 00011001b, 00011010b, 00011011b, 00011100b, 00011101b, |
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385 // 00011110b and 00011111b |
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386 int idx = code & 0xff; |
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387 curr.setEOSPath(curr.isEOSPath() | isEOS); |
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388 for (int i = 0; i < (1 << align); i++) { |
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389 Node child = curr.getOrCreateChild(idx | i); |
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390 child.setSymbol(symbol); |
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391 child.setEOSPath(child.isEOSPath() | isEOS); |
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392 child.setLength(bitLength - l); |
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393 } |
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394 } |
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395 |
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396 /* |
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397 * A node in the Huffman trie. |
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398 */ |
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399 interface Node { |
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400 |
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401 boolean isEOSPath(); |
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402 |
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403 void setEOSPath(boolean value); |
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404 |
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405 boolean isLeaf(); |
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406 |
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407 Node getChild(int index); |
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408 |
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409 Node getOrCreateChild(int index); |
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410 |
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411 Node[] getChildren(); |
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412 |
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413 char getSymbol(); |
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414 |
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415 void setSymbol(char symbol); |
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416 |
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417 int getLength(); |
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418 |
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419 void setLength(int value); |
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420 } |
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421 |
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422 /* |
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423 * Mutable nodes used for initial construction of the Huffman trie. |
|
424 * (These nodes are perfectly ok to be used after that.) |
|
425 */ |
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426 static final class TemporaryNode implements Node { |
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427 |
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428 private char symbol; |
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429 private boolean eosPath; |
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430 private TemporaryNode[] children; |
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431 private int length; |
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432 |
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433 @Override |
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434 public TemporaryNode getOrCreateChild(int index) { |
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435 ensureChildrenExist(); |
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436 if (children[index] == null) { |
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437 children[index] = new TemporaryNode(); |
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438 } |
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439 return children[index]; |
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440 } |
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441 |
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442 private void ensureChildrenExist() { |
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443 if (children == null) { |
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444 children = new TemporaryNode[256]; |
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445 } |
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446 } |
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447 |
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448 @Override |
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449 public boolean isLeaf() { |
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450 return children == null; |
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451 } |
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452 |
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453 @Override |
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454 public boolean isEOSPath() { |
|
455 return eosPath; |
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456 } |
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457 |
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458 @Override |
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459 public void setEOSPath(boolean value) { |
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460 eosPath = value; |
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461 } |
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462 |
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463 @Override |
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464 public TemporaryNode getChild(int index) { |
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465 ensureChildrenExist(); |
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466 return children[index]; |
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467 } |
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468 |
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469 @Override |
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470 public Node[] getChildren() { |
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471 if (children == null) { |
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472 return new Node[0]; |
|
473 } |
|
474 return children; |
|
475 } |
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476 |
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477 @Override |
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478 public char getSymbol() { |
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479 return symbol; |
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480 } |
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481 |
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482 @Override |
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483 public int getLength() { |
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484 return length; |
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485 } |
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486 |
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487 @Override |
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488 public void setSymbol(char value) { |
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489 this.symbol = value; |
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490 } |
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491 |
|
492 @Override |
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493 public void setLength(int value) { |
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494 this.length = value; |
|
495 } |
|
496 } |
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497 |
|
498 /* |
|
499 * Immutable node used to construct traversal-only Huffman trie. |
|
500 * |
|
501 * Once the trie has been built, the support of modifications is no longer |
|
502 * required. An immutable trie should be used. Not only it will help to |
|
503 * catch possible bugs, but hopefully speedup the traversal operations. |
|
504 */ |
|
505 static final class ImmutableNode implements Node { |
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506 |
|
507 private final char symbol; |
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508 private final boolean eosPath; |
|
509 private final int length; |
|
510 private final List<ImmutableNode> children; |
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511 |
|
512 public static ImmutableNode copyOf(Node node) { |
|
513 if (node.isLeaf()) { |
|
514 return new ImmutableNode(node.getSymbol(), node.isEOSPath(), |
|
515 node.getLength()); |
|
516 } |
|
517 Node[] children = node.getChildren(); |
|
518 ImmutableNode[] immutableChildren = new ImmutableNode[children.length]; |
|
519 for (int i = 0; i < children.length; i++) { |
|
520 immutableChildren[i] = copyOf(children[i]); |
|
521 } |
|
522 return new ImmutableNode(node.isEOSPath(), node.getLength(), |
|
523 immutableChildren); |
|
524 } |
|
525 |
|
526 /* Creates a leaf node */ |
|
527 private ImmutableNode(char symbol, |
|
528 boolean eosPath, |
|
529 int length) { |
|
530 this.symbol = symbol; |
|
531 this.eosPath = eosPath; |
|
532 this.length = length; |
|
533 this.children = List.of(); |
|
534 } |
|
535 |
|
536 /* Creates a node with children */ |
|
537 private ImmutableNode(boolean eosPath, |
|
538 int length, |
|
539 ImmutableNode[] children) |
|
540 { |
|
541 this.symbol = 0; |
|
542 this.eosPath = eosPath; |
|
543 this.length = length; |
|
544 if (children.length == 0) { |
|
545 throw new IllegalArgumentException(); |
|
546 } |
|
547 // A list produced by List.of should not be slower than array for |
|
548 // accessing elements by index, and hopefully use additional |
|
549 // optimizations (e.g. jdk.internal.vm.annotation.Stable) |
|
550 this.children = List.of(children); |
|
551 } |
|
552 |
|
553 @Override |
|
554 public boolean isLeaf() { |
|
555 return children.isEmpty(); |
|
556 } |
|
557 |
|
558 @Override |
|
559 public boolean isEOSPath() { |
|
560 return eosPath; |
|
561 } |
|
562 |
|
563 @Override |
|
564 public void setEOSPath(boolean value) { |
|
565 throw new UnsupportedOperationException(); |
|
566 } |
|
567 |
|
568 @Override |
|
569 public ImmutableNode getChild(int index) { |
|
570 return children.get(index); |
|
571 } |
|
572 |
|
573 @Override |
|
574 public ImmutableNode getOrCreateChild(int index) { |
|
575 throw new UnsupportedOperationException(); |
|
576 } |
|
577 |
|
578 @Override |
|
579 public ImmutableNode[] getChildren() { |
|
580 // This method is not expected to be called on an immutable node. |
|
581 // If it is called, it requires some investigation. |
|
582 throw new UnsupportedOperationException(); |
|
583 } |
|
584 |
|
585 @Override |
|
586 public char getSymbol() { |
|
587 return symbol; |
|
588 } |
|
589 |
|
590 @Override |
|
591 public void setSymbol(char symbol) { |
|
592 throw new UnsupportedOperationException(); |
|
593 } |
|
594 |
|
595 @Override |
|
596 public int getLength() { |
|
597 return length; |
|
598 } |
|
599 |
|
600 @Override |
|
601 public void setLength(int value) { |
|
602 throw new UnsupportedOperationException(); |
|
603 } |
|
604 } |
|
605 |
|
606 static final class Reader implements Huffman.Reader { |
|
607 |
|
608 private Node curr = root; // current position in the trie |
|
609 private long buffer; // bits left from the previous match (aligned to the left, or MSB) |
|
610 private int bufferLen; // number of bits in the buffer |
|
611 private int len; // length (in bits) of path to curr |
|
612 private boolean done; |
|
613 |
|
614 @Override |
|
615 public void read(ByteBuffer source, |
|
616 Appendable destination, |
|
617 boolean isLast) throws IOException |
|
618 { |
|
619 read(source, destination, true, isLast); |
|
620 } |
|
621 |
|
622 @Override |
|
623 public void reset() { |
|
624 curr = root; |
|
625 len = 0; |
|
626 buffer = 0; |
|
627 bufferLen = 0; |
|
628 done = false; |
|
629 } |
|
630 |
|
631 @SuppressWarnings("fallthrough") |
|
632 void read(ByteBuffer source, |
|
633 Appendable destination, |
|
634 boolean reportEOS, /* reportEOS is exposed for tests */ |
|
635 boolean isLast) throws IOException |
|
636 { |
|
637 while (!done) { |
|
638 // read as much as possible (up to 8 bytes) |
|
639 int remaining = source.remaining(); |
|
640 int nBytes = Math.min((64 - bufferLen) >> 3, remaining); |
|
641 switch (nBytes) { |
|
642 case 0: |
|
643 break; |
|
644 case 3: |
|
645 readByte(source); |
|
646 case 2: |
|
647 readByte(source); |
|
648 case 1: |
|
649 readByte(source); |
|
650 break; |
|
651 case 7: |
|
652 readByte(source); |
|
653 case 6: |
|
654 readByte(source); |
|
655 case 5: |
|
656 readByte(source); |
|
657 case 4: |
|
658 readInt(source); |
|
659 break; |
|
660 case 8: |
|
661 readLong(source); |
|
662 break; |
|
663 default: |
|
664 throw new InternalError(String.valueOf(nBytes)); |
|
665 } |
|
666 // write as much as possible |
|
667 while (true) { |
|
668 if (bufferLen < 8) { |
|
669 if (nBytes < remaining) { // read again |
|
670 break; |
|
671 } else if (!isLast) { // exit the method to accept more input |
|
672 return; |
|
673 } else if (bufferLen > 0) { // no more data is expected, pad |
|
674 // (this padding may be done more than once) |
|
675 buffer |= ((0xff00000000000000L >>> bufferLen) |
|
676 & 0xff00000000000000L); |
|
677 // do not update bufferLen, since all those ones are |
|
678 // synthetic and are appended merely for the sake of |
|
679 // lookup |
|
680 } else { |
|
681 done = true; |
|
682 break; |
|
683 } |
|
684 } |
|
685 int idx = (int) (buffer >>> 56); |
|
686 Node node = curr.getChild(idx); |
|
687 if (node == null) { // TODO: TEST |
|
688 throw new IOException("Unexpected byte"); |
|
689 } |
|
690 if (node.isLeaf()) { |
|
691 if (node.getLength() > bufferLen) { // matched more than we actually could (because of padding) |
|
692 throw new IOException( |
|
693 "Not a EOS prefix padding or unexpected end of data"); |
|
694 } |
|
695 if (reportEOS && node.isEOSPath()) { |
|
696 throw new IOException("Encountered EOS"); |
|
697 } |
|
698 destination.append(node.getSymbol()); |
|
699 curr = root; |
|
700 len = 0; |
|
701 } else { |
|
702 curr = node; |
|
703 // because of the padding, we can't match more bits than |
|
704 // there are currently in the buffer |
|
705 len += Math.min(bufferLen, node.getLength()); |
|
706 } |
|
707 buffer <<= node.getLength(); |
|
708 bufferLen -= node.getLength(); |
|
709 } |
|
710 if (done && (curr.isEOSPath() && len > 7)) { |
|
711 throw new IOException( |
|
712 "Padding is too long (len=" + len + ") " |
|
713 + "or unexpected end of data"); |
|
714 } |
|
715 } |
|
716 } |
|
717 |
|
718 private void readLong(ByteBuffer source) { |
|
719 buffer = source.getLong(); |
|
720 bufferLen = 64; |
|
721 } |
|
722 |
|
723 private void readInt(ByteBuffer source) { |
|
724 long b; |
|
725 b = source.getInt() & 0x00000000ffffffffL; |
|
726 buffer |= (b << (32 - bufferLen)); |
|
727 bufferLen += 32; |
|
728 } |
|
729 |
|
730 private void readByte(ByteBuffer source) { |
|
731 long b = source.get() & 0x00000000000000ffL; |
|
732 buffer |= (b << (56 - bufferLen)); |
|
733 bufferLen += 8; |
|
734 } |
|
735 } |
|
736 |
|
737 static final class Writer implements Huffman.Writer { |
|
738 |
|
739 private CharSequence source; |
|
740 private boolean padded; |
|
741 private int pos; |
|
742 private int end; |
|
743 private long buffer; |
|
744 private int bufferLen; |
|
745 |
|
746 @Override |
|
747 public QuickHuffman.Writer from(CharSequence input, int start, int end) { |
|
748 Objects.checkFromToIndex(start, end, input.length()); |
|
749 this.pos = start; |
|
750 this.end = end; |
|
751 this.source = input; |
|
752 return this; |
|
753 } |
|
754 |
|
755 @SuppressWarnings("fallthrough") |
|
756 @Override |
|
757 public boolean write(ByteBuffer destination) { |
|
758 while (true) { |
|
759 while (bufferLen < 32 && pos < end) { |
|
760 char c = source.charAt(pos++); |
|
761 buffer |= (codeValueOf(c) >>> bufferLen); // append |
|
762 bufferLen += codeLengthOf(c); |
|
763 } |
|
764 if (bufferLen == 0) { |
|
765 return true; |
|
766 } |
|
767 if (pos >= end && !padded) { // no more chars, pad |
|
768 padded = true; |
|
769 buffer |= (EOS_MSB >>> bufferLen); |
|
770 bufferLen = bytesForBits(bufferLen) << 3; |
|
771 } |
|
772 // The number of bytes that can be written at once |
|
773 // (calculating in bytes, not bits, since |
|
774 // destination.remaining() * 8 might overflow) |
|
775 |
|
776 int nBytes = Math.min(bytesForBits(bufferLen), destination.remaining()); // ceil? |
|
777 switch (nBytes) { |
|
778 case 0: |
|
779 return false; |
|
780 case 1: |
|
781 case 2: |
|
782 case 3: |
|
783 destination.put((byte) (buffer >>> 56)); |
|
784 buffer <<= 8; |
|
785 bufferLen -= 8; |
|
786 break; |
|
787 default: |
|
788 destination.putInt((int) (buffer >>> 32)); |
|
789 buffer <<= 32; |
|
790 bufferLen -= 32; |
|
791 break; |
|
792 } |
|
793 } |
|
794 } |
|
795 |
|
796 @Override |
|
797 public QuickHuffman.Writer reset() { |
|
798 source = null; |
|
799 buffer = 0; |
|
800 bufferLen = 0; |
|
801 end = 0; |
|
802 pos = 0; |
|
803 padded = false; |
|
804 return this; |
|
805 } |
|
806 |
|
807 @Override |
|
808 public int lengthOf(CharSequence value, int start, int end) { |
|
809 int len = 0; |
|
810 for (int i = start; i < end; i++) { |
|
811 char c = value.charAt(i); |
|
812 len += codeLengthOf(c); |
|
813 } |
|
814 return bytesForBits(len); |
|
815 } |
|
816 } |
|
817 |
|
818 /* |
|
819 * Returns the number of bytes the given number of bits constitute. |
|
820 */ |
|
821 private static int bytesForBits(int n) { |
|
822 assert (n / 8 + (n % 8 != 0 ? 1 : 0)) == (n + 7) / 8 |
|
823 && (n + 7) / 8 == ((n + 7) >> 3) : n; |
|
824 return (n + 7) >> 3; |
|
825 } |
|
826 } |