1 | package LZMA;
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2 |
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3 | import java.io.InputStream;
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4 | import java.io.IOException;
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5 |
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6 | class CRangeDecoder {
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7 |
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8 | final static int kNumTopBits = 24;
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9 | final static int kTopValue = (1 << kNumTopBits);
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10 | final static int kTopValueMask = ~(kTopValue-1);
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11 |
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12 | final static int kNumBitModelTotalBits = 11;
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13 | final static int kBitModelTotal = (1 << kNumBitModelTotalBits);
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14 | final static int kNumMoveBits = 5;
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15 |
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16 | InputStream inStream;
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17 |
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18 | int Range;
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19 | int Code;
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20 |
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21 | byte buffer[];
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22 | int buffer_size;
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23 | int buffer_ind;
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24 |
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25 | CRangeDecoder( InputStream iStream ) throws IOException {
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26 | this.buffer = new byte[1<<14];
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27 | this.inStream = iStream;
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28 | this.Code = 0;
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29 | this.Range = -1; // 0xFFFFFFFFL;
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30 | for(int i = 0; i < 5; i++)
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31 | this.Code = (this.Code << 8) | (Readbyte());
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32 | }
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33 |
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34 | int Readbyte() throws IOException {
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35 | if (buffer_size == buffer_ind) {
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36 | buffer_size = inStream.read(buffer);
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37 | buffer_ind = 0;
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38 |
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39 | if (buffer_size < 1)
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40 | throw new LzmaException ("LZMA : Data Error");
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41 | }
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42 | return buffer[buffer_ind++] & 0xFF;
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43 | }
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44 |
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45 | int DecodeDirectBits(int numTotalBits) throws IOException {
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46 | int result = 0;
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47 | for (int i = numTotalBits; i > 0; i--) {
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48 | Range >>>= 1;
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49 | int t = ((Code - Range) >>> 31);
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50 | Code -= Range & (t - 1);
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51 | result = (result << 1) | (1 - t);
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52 |
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53 | if (Range < kTopValue) // because of "Range >>>= 1", 0 <= Range <= 0x7FFFFFFF
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54 | {
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55 | Code = (Code << 8) | Readbyte();
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56 | Range <<= 8;
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57 | }
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58 | }
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59 | return result;
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60 | }
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61 |
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62 | int BitDecode(int prob[],int index) throws IOException {
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63 | int newBound = (this.Range >>> kNumBitModelTotalBits) * prob[index];
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64 | if ((this.Code & 0xFFFFFFFFL) < (newBound & 0xFFFFFFFFL)) // unsigned comparison
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65 | {
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66 | this.Range = newBound;
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67 | prob[index] += (kBitModelTotal - prob[index]) >>> kNumMoveBits;
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68 | // if ((this.Range & 0xFFFFFFFFL) < Decoder.kTopValue)
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69 | if ((this.Range & kTopValueMask) == 0) {
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70 | this.Code = (this.Code << 8) | Readbyte();
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71 | this.Range <<= 8;
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72 | }
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73 | return 0;
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74 | } else {
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75 | this.Range -= newBound;
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76 | this.Code -= newBound;
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77 | prob[index] -= (prob[index]) >>> kNumMoveBits;
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78 | // if ((this.Range & 0xFFFFFFFFL) < Decoder.kTopValue)
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79 | if ((this.Range & kTopValueMask) == 0) {
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80 | this.Code = (this.Code << 8) | this.Readbyte();
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81 | this.Range <<= 8;
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82 | }
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83 | return 1;
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84 | }
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85 | }
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86 |
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87 | int BitTreeDecode(int probs [], int index , int numLevels) throws IOException {
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88 | int mi = 1;
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89 | for(int i = numLevels; i > 0; i--) {
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90 | mi = (mi + mi) + BitDecode(probs, index + mi);
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91 | }
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92 | return mi - (1 << numLevels);
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93 | }
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94 |
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95 | int ReverseBitTreeDecode(int probs[] ,int index, int numLevels) throws IOException {
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96 | int mi = 1;
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97 | int symbol = 0;
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98 |
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99 | for(int i = 0; i < numLevels; i++) {
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100 | int bit = BitDecode(probs, index + mi);
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101 | mi = mi + mi + bit;
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102 | symbol |= (bit << i);
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103 | }
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104 | return symbol;
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105 | }
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106 |
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107 | byte LzmaLiteralDecode(int probs[],int index) throws IOException {
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108 | int symbol = 1;
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109 | do {
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110 | symbol = (symbol + symbol) | BitDecode(probs, index + symbol);
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111 | } while (symbol < 0x100);
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112 |
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113 | return (byte)symbol;
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114 | }
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115 |
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116 | byte LzmaLiteralDecodeMatch(int probs [], int index, byte matchbyte) throws IOException {
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117 | int symbol = 1;
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118 | do {
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119 | int matchBit = (matchbyte >> 7) & 1;
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120 | matchbyte <<= 1;
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121 | int bit = BitDecode(probs , index + ((1 + matchBit) << 8) + symbol);
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122 | symbol = (symbol << 1) | bit;
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123 |
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124 | if (matchBit != bit) {
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125 | while (symbol < 0x100) {
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126 | symbol = (symbol + symbol) | BitDecode(probs , index + symbol);
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127 | }
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128 | break;
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129 | }
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130 | } while (symbol < 0x100);
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131 |
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132 | return (byte)symbol;
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133 | }
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134 |
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135 | final static int kNumPosBitsMax = 4;
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136 | final static int kNumPosStatesMax = (1 << kNumPosBitsMax);
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137 |
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138 | final static int kLenNumLowBits = 3;
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139 | final static int kLenNumLowSymbols = (1 << kLenNumLowBits);
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140 | final static int kLenNumMidBits = 3;
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141 | final static int kLenNumMidSymbols = (1 << kLenNumMidBits);
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142 | final static int kLenNumHighBits = 8;
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143 | final static int kLenNumHighSymbols = (1 << kLenNumHighBits);
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144 |
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145 | final static int LenChoice = 0;
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146 | final static int LenChoice2 = (LenChoice + 1);
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147 | final static int LenLow = (LenChoice2 + 1);
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148 | final static int LenMid = (LenLow + (kNumPosStatesMax << kLenNumLowBits));
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149 | final static int LenHigh = (LenMid + (kNumPosStatesMax << kLenNumMidBits));
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150 | final static int kNumLenProbs = (LenHigh + kLenNumHighSymbols);
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151 |
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152 | int LzmaLenDecode(int probs[], int index, int posState) throws IOException {
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153 | if(BitDecode(probs, index + LenChoice) == 0)
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154 | return BitTreeDecode(probs, index + LenLow +
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155 | (posState << kLenNumLowBits), kLenNumLowBits);
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156 |
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157 | if(BitDecode(probs, index + LenChoice2) == 0)
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158 | return kLenNumLowSymbols + BitTreeDecode(probs, index + LenMid +
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159 | (posState << kLenNumMidBits), kLenNumMidBits);
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160 |
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161 | return kLenNumLowSymbols + kLenNumMidSymbols +
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162 | BitTreeDecode(probs, index + LenHigh, kLenNumHighBits);
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163 | }
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164 | }
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165 |
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