1 // Copyright (c) 1998-2009 Nokia Corporation and/or its subsidiary(-ies). |
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2 // All rights reserved. |
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3 // This component and the accompanying materials are made available |
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4 // under the terms of "Eclipse Public License v1.0" |
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5 // which accompanies this distribution, and is available |
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6 // at the URL "http://www.eclipse.org/legal/epl-v10.html". |
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7 // |
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8 // Initial Contributors: |
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9 // Nokia Corporation - initial contribution. |
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10 // |
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11 // Contributors: |
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12 // |
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13 // Description: |
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14 // e32tools\petran\Szip\deflate.cpp |
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15 // |
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16 // |
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17 |
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18 #include "deflate.h" |
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19 #include "h_utl.h" |
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20 #include "panic.h" |
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21 |
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22 class HDeflateHash |
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23 { |
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24 public: |
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25 inline static HDeflateHash* NewLC(TInt aLinks); |
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26 // |
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27 inline TInt First(const TUint8* aPtr,TInt aPos); |
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28 inline TInt Next(TInt aPos,TInt aOffset) const; |
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29 private: |
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30 inline HDeflateHash(); |
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31 inline static TInt Hash(const TUint8* aPtr); |
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32 private: |
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33 typedef TUint16 TOffset; |
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34 private: |
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35 TInt iHash[256]; |
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36 TOffset iOffset[1]; // or more |
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37 }; |
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38 |
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39 class MDeflater |
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40 { |
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41 public: |
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42 void DeflateL(const TUint8* aBase,TInt aLength); |
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43 inline virtual ~MDeflater() { }; |
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44 private: |
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45 const TUint8* DoDeflateL(const TUint8* aBase,const TUint8* aEnd,HDeflateHash& aHash); |
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46 static TInt Match(const TUint8* aPtr,const TUint8* aEnd,TInt aPos,HDeflateHash& aHas); |
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47 void SegmentL(TInt aLength,TInt aDistance); |
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48 virtual void LitLenL(TInt aCode) =0; |
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49 virtual void OffsetL(TInt aCode) =0; |
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50 virtual void ExtraL(TInt aLen,TUint aBits) =0; |
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51 }; |
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52 |
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53 class TDeflateStats : public MDeflater |
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54 { |
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55 public: |
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56 inline TDeflateStats(TEncoding& aEncoding); |
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57 inline virtual ~TDeflateStats() { } |
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58 private: |
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59 // from MDeflater |
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60 void LitLenL(TInt aCode); |
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61 void OffsetL(TInt aCode); |
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62 void ExtraL(TInt aLen,TUint aBits); |
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63 private: |
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64 TEncoding& iEncoding; |
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65 }; |
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66 |
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67 class TDeflater : public MDeflater |
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68 { |
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69 public: |
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70 inline TDeflater(TBitOutput& aOutput,const TEncoding& aEncoding); |
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71 inline virtual ~TDeflater() { }; |
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72 private: |
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73 // from MDeflater |
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74 void LitLenL(TInt aCode); |
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75 void OffsetL(TInt aCode); |
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76 void ExtraL(TInt aLen,TUint aBits); |
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77 private: |
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78 TBitOutput& iOutput; |
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79 const TEncoding& iEncoding; |
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80 }; |
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81 |
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82 |
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83 // Class HDeflateHash |
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84 |
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85 inline HDeflateHash::HDeflateHash() |
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86 {TInt* p=iHash+256;do *--p=-KDeflateMaxDistance-1; while (p>iHash);} |
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87 |
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88 inline HDeflateHash* HDeflateHash::NewLC(TInt aLinks) |
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89 { |
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90 return new(HMem::Alloc(0,_FOFF(HDeflateHash,iOffset[0]) + (sizeof(TOffset) * Min(aLinks,KDeflateMaxDistance)))) HDeflateHash; |
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91 } |
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92 |
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93 inline TInt HDeflateHash::Hash(const TUint8* aPtr) |
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94 { |
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95 TUint x=aPtr[0]|(aPtr[1]<<8)|(aPtr[2]<<16); |
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96 return (x*KDeflateHashMultiplier)>>KDeflateHashShift; |
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97 } |
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98 |
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99 inline TInt HDeflateHash::First(const TUint8* aPtr,TInt aPos) |
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100 { |
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101 TInt h=Hash(aPtr); |
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102 TInt offset=Min(aPos-iHash[h],KDeflateMaxDistance<<1); |
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103 iHash[h]=aPos; |
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104 iOffset[aPos&(KDeflateMaxDistance-1)]=TOffset(offset); |
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105 return offset; |
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106 } |
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107 |
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108 inline TInt HDeflateHash::Next(TInt aPos,TInt aOffset) const |
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109 {return aOffset+iOffset[(aPos-aOffset)&(KDeflateMaxDistance-1)];} |
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110 |
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111 |
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112 // Class TDeflater |
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113 // |
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114 // generic deflation algorithm, can do either statistics and the encoder |
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115 |
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116 TInt MDeflater::Match(const TUint8* aPtr,const TUint8* aEnd,TInt aPos,HDeflateHash& aHash) |
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117 { |
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118 TInt offset=aHash.First(aPtr,aPos); |
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119 if (offset>KDeflateMaxDistance) |
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120 return 0; |
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121 TInt match=0; |
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122 aEnd=Min(aEnd,aPtr+KDeflateMaxLength); |
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123 TUint8 c=*aPtr; |
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124 do |
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125 { |
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126 const TUint8* p=aPtr-offset; |
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127 if (p[match>>16]==c) |
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128 { // might be a better match |
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129 const TUint8* m=aPtr; |
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130 for (;;) |
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131 { |
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132 if (*p++!=*m++) |
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133 break; |
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134 if (m<aEnd) |
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135 continue; |
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136 return ((m-aPtr)<<16)|offset; |
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137 } |
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138 TInt l=m-aPtr-1; |
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139 if (l>match>>16) |
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140 { |
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141 match=(l<<16)|offset; |
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142 c=m[-1]; |
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143 } |
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144 } |
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145 offset=aHash.Next(aPos,offset); |
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146 } while (offset<=KDeflateMaxDistance); |
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147 return match; |
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148 } |
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149 |
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150 const TUint8* MDeflater::DoDeflateL(const TUint8* aBase,const TUint8* aEnd,HDeflateHash& aHash) |
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151 // |
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152 // Apply the deflation algorithm to the data [aBase,aEnd) |
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153 // Return a pointer after the last byte that was deflated (which may not be aEnd) |
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154 // |
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155 { |
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156 const TUint8* ptr=aBase; |
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157 TInt prev=0; // the previous deflation match |
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158 do |
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159 { |
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160 TInt match=Match(ptr,aEnd,ptr-aBase,aHash); |
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161 // Extra deflation applies two optimisations which double the time taken |
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162 // 1. If we have a match at p, then test for a better match at p+1 before using it |
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163 // 2. When we have a match, add the hash links for all the data which will be skipped |
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164 if (match>>16 < prev>>16) |
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165 { // use the previous match--it was better |
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166 TInt len=prev>>16; |
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167 SegmentL(len,prev-(len<<16)); |
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168 // fill in missing hash entries for better compression |
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169 const TUint8* e=ptr+len-2; |
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170 do |
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171 { |
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172 ++ptr; |
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173 if (ptr + 2 < aEnd) |
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174 aHash.First(ptr,ptr-aBase); |
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175 } while (ptr<e); |
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176 prev=0; |
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177 } |
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178 else if (match<=(KDeflateMinLength<<16)) |
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179 LitLenL(*ptr); // no deflation match here |
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180 else |
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181 { // save this match and test the next position |
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182 if (prev) // we had a match at ptr-1, but this is better |
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183 LitLenL(ptr[-1]); |
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184 prev=match; |
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185 } |
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186 ++ptr; |
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187 } while (ptr+KDeflateMinLength-1<aEnd); |
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188 if (prev) |
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189 { // emit the stored match |
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190 TInt len=prev>>16; |
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191 SegmentL(len,prev-(len<<16)); |
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192 ptr+=len-1; |
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193 } |
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194 return ptr; |
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195 } |
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196 |
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197 void MDeflater::DeflateL(const TUint8* aBase,TInt aLength) |
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198 // |
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199 // The generic deflation algorithm |
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200 // |
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201 { |
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202 const TUint8* end=aBase+aLength; |
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203 if (aLength>KDeflateMinLength) |
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204 { // deflation kicks in if there is enough data |
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205 HDeflateHash* hash=HDeflateHash::NewLC(aLength); |
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206 if(hash==NULL) |
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207 Panic(EHuffmanOutOfMemory); |
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208 |
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209 aBase=DoDeflateL(aBase,end,*hash); |
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210 delete hash; |
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211 } |
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212 while (aBase<end) // emit remaining bytes |
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213 LitLenL(*aBase++); |
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214 LitLenL(TEncoding::EEos); // eos marker |
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215 } |
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216 |
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217 void MDeflater::SegmentL(TInt aLength,TInt aDistance) |
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218 // |
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219 // Turn a (length,offset) pair into the deflation codes+extra bits before calling |
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220 // the specific LitLen(), Offset() and Extra() functions. |
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221 // |
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222 { |
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223 aLength-=KDeflateMinLength; |
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224 TInt extralen=0; |
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225 TUint len=aLength; |
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226 while (len>=8) |
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227 { |
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228 ++extralen; |
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229 len>>=1; |
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230 } |
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231 LitLenL((extralen<<2)+len+TEncoding::ELiterals); |
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232 if (extralen) |
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233 ExtraL(extralen,aLength); |
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234 // |
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235 aDistance--; |
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236 extralen=0; |
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237 TUint dist=aDistance; |
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238 while (dist>=8) |
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239 { |
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240 ++extralen; |
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241 dist>>=1; |
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242 } |
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243 OffsetL((extralen<<2)+dist); |
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244 if (extralen) |
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245 ExtraL(extralen,aDistance); |
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246 } |
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247 |
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248 // Class TDeflateStats |
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249 // |
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250 // This class analyses the data stream to generate the frequency tables |
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251 // for the deflation algorithm |
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252 |
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253 inline TDeflateStats::TDeflateStats(TEncoding& aEncoding) |
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254 :iEncoding(aEncoding) |
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255 {} |
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256 |
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257 void TDeflateStats::LitLenL(TInt aCode) |
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258 { |
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259 ++iEncoding.iLitLen[aCode]; |
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260 } |
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261 |
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262 void TDeflateStats::OffsetL(TInt aCode) |
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263 { |
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264 ++iEncoding.iDistance[aCode]; |
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265 } |
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266 |
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267 void TDeflateStats::ExtraL(TInt,TUint) |
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268 {} |
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269 |
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270 // Class TDeflater |
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271 // |
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272 // Extends MDeflater to provide huffman encoding of the output |
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273 |
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274 inline TDeflater::TDeflater(TBitOutput& aOutput,const TEncoding& aEncoding) |
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275 // |
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276 // construct for encoding |
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277 // |
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278 :iOutput(aOutput),iEncoding(aEncoding) |
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279 {} |
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280 |
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281 void TDeflater::LitLenL(TInt aCode) |
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282 { |
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283 iOutput.HuffmanL(iEncoding.iLitLen[aCode]); |
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284 } |
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285 |
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286 void TDeflater::OffsetL(TInt aCode) |
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287 { |
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288 iOutput.HuffmanL(iEncoding.iDistance[aCode]); |
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289 } |
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290 |
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291 void TDeflater::ExtraL(TInt aLen,TUint aBits) |
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292 { |
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293 iOutput.WriteL(aBits,aLen); |
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294 } |
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295 |
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296 void DoDeflateL(const TUint8* aBuf,TInt aLength,TBitOutput& aOutput,TEncoding& aEncoding) |
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297 { |
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298 // analyse the data for symbol frequency |
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299 TDeflateStats analyser(aEncoding); |
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300 analyser.DeflateL(aBuf,aLength); |
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301 |
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302 // generate the required huffman encodings |
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303 Huffman::HuffmanL(aEncoding.iLitLen,TEncoding::ELitLens,aEncoding.iLitLen); |
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304 Huffman::HuffmanL(aEncoding.iDistance,TEncoding::EDistances,aEncoding.iDistance); |
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305 |
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306 // Store the encoding table |
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307 Huffman::ExternalizeL(aOutput,aEncoding.iLitLen,KDeflationCodes); |
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308 |
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309 // generate the tables |
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310 Huffman::Encoding(aEncoding.iLitLen,TEncoding::ELitLens,aEncoding.iLitLen); |
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311 Huffman::Encoding(aEncoding.iDistance,TEncoding::EDistances,aEncoding.iDistance); |
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312 |
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313 // now finally deflate the data with the generated encoding |
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314 TDeflater deflater(aOutput,aEncoding); |
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315 deflater.DeflateL(aBuf,aLength); |
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316 aOutput.PadL(1); |
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317 } |
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318 |
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319 void DeflateL(const TUint8* aBuf, TInt aLength, TBitOutput& aOutput) |
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320 { |
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321 TEncoding* encoding=new TEncoding; |
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322 HMem::FillZ(encoding,sizeof(TEncoding)); |
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323 DoDeflateL(aBuf,aLength,aOutput,*encoding); |
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324 } |
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325 |
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