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| 1 // Compress/RangeCoder.h | |
| 2 | |
| 3 #ifndef __COMPRESS_RANGE_CODER_H | |
| 4 #define __COMPRESS_RANGE_CODER_H | |
| 5 | |
| 6 #include "../Common/InBuffer.h" | |
| 7 #include "../Common/OutBuffer.h" | |
| 8 | |
| 9 namespace NCompress { | |
| 10 namespace NRangeCoder { | |
| 11 | |
| 12 const int kNumTopBits = 24; | |
| 13 const UInt32 kTopValue = (1 << kNumTopBits); | |
| 14 | |
| 15 class CEncoder | |
| 16 { | |
| 17 UInt32 _cacheSize; | |
| 18 Byte _cache; | |
| 19 public: | |
| 20 UInt64 Low; | |
| 21 UInt32 Range; | |
| 22 COutBuffer Stream; | |
| 23 bool Create(UInt32 bufferSize) { return Stream.Create(bufferSize); } | |
| 24 | |
| 25 void SetStream(ISequentialOutStream *stream) { Stream.SetStream(stream); } | |
| 26 void Init() | |
| 27 { | |
| 28 Stream.Init(); | |
| 29 Low = 0; | |
| 30 Range = 0xFFFFFFFF; | |
| 31 _cacheSize = 1; | |
| 32 _cache = 0; | |
| 33 } | |
| 34 | |
| 35 void FlushData() | |
| 36 { | |
| 37 // Low += 1; | |
| 38 for(int i = 0; i < 5; i++) | |
| 39 ShiftLow(); | |
| 40 } | |
| 41 | |
| 42 HRESULT FlushStream() { return Stream.Flush(); } | |
| 43 | |
| 44 void ReleaseStream() { Stream.ReleaseStream(); } | |
| 45 | |
| 46 void Encode(UInt32 start, UInt32 size, UInt32 total) | |
| 47 { | |
| 48 Low += start * (Range /= total); | |
| 49 Range *= size; | |
| 50 while (Range < kTopValue) | |
| 51 { | |
| 52 Range <<= 8; | |
| 53 ShiftLow(); | |
| 54 } | |
| 55 } | |
| 56 | |
| 57 void ShiftLow() | |
| 58 { | |
| 59 if ((UInt32)Low < (UInt32)0xFF000000 || (int)(Low >> 32) != 0) | |
| 60 { | |
| 61 Byte temp = _cache; | |
| 62 do | |
| 63 { | |
| 64 Stream.WriteByte((Byte)(temp + (Byte)(Low >> 32))); | |
| 65 temp = 0xFF; | |
| 66 } | |
| 67 while(--_cacheSize != 0); | |
| 68 _cache = (Byte)((UInt32)Low >> 24); | |
| 69 } | |
| 70 _cacheSize++; | |
| 71 Low = (UInt32)Low << 8; | |
| 72 } | |
| 73 | |
| 74 void EncodeDirectBits(UInt32 value, int numBits) | |
| 75 { | |
| 76 for (numBits--; numBits >= 0; numBits--) | |
| 77 { | |
| 78 Range >>= 1; | |
| 79 Low += Range & (0 - ((value >> numBits) & 1)); | |
| 80 if (Range < kTopValue) | |
| 81 { | |
| 82 Range <<= 8; | |
| 83 ShiftLow(); | |
| 84 } | |
| 85 } | |
| 86 } | |
| 87 | |
| 88 void EncodeBit(UInt32 size0, UInt32 numTotalBits, UInt32 symbol) | |
| 89 { | |
| 90 UInt32 newBound = (Range >> numTotalBits) * size0; | |
| 91 if (symbol == 0) | |
| 92 Range = newBound; | |
| 93 else | |
| 94 { | |
| 95 Low += newBound; | |
| 96 Range -= newBound; | |
| 97 } | |
| 98 while (Range < kTopValue) | |
| 99 { | |
| 100 Range <<= 8; | |
| 101 ShiftLow(); | |
| 102 } | |
| 103 } | |
| 104 | |
| 105 UInt64 GetProcessedSize() { return Stream.GetProcessedSize() + _cacheSize + 4
; } | |
| 106 }; | |
| 107 | |
| 108 class CDecoder | |
| 109 { | |
| 110 public: | |
| 111 CInBuffer Stream; | |
| 112 UInt32 Range; | |
| 113 UInt32 Code; | |
| 114 bool Create(UInt32 bufferSize) { return Stream.Create(bufferSize); } | |
| 115 | |
| 116 void Normalize() | |
| 117 { | |
| 118 while (Range < kTopValue) | |
| 119 { | |
| 120 Code = (Code << 8) | Stream.ReadByte(); | |
| 121 Range <<= 8; | |
| 122 } | |
| 123 } | |
| 124 | |
| 125 void SetStream(ISequentialInStream *stream) { Stream.SetStream(stream); } | |
| 126 void Init() | |
| 127 { | |
| 128 Stream.Init(); | |
| 129 Code = 0; | |
| 130 Range = 0xFFFFFFFF; | |
| 131 for(int i = 0; i < 5; i++) | |
| 132 Code = (Code << 8) | Stream.ReadByte(); | |
| 133 } | |
| 134 | |
| 135 void ReleaseStream() { Stream.ReleaseStream(); } | |
| 136 | |
| 137 UInt32 GetThreshold(UInt32 total) | |
| 138 { | |
| 139 return (Code) / ( Range /= total); | |
| 140 } | |
| 141 | |
| 142 void Decode(UInt32 start, UInt32 size) | |
| 143 { | |
| 144 Code -= start * Range; | |
| 145 Range *= size; | |
| 146 Normalize(); | |
| 147 } | |
| 148 | |
| 149 UInt32 DecodeDirectBits(int numTotalBits) | |
| 150 { | |
| 151 UInt32 range = Range; | |
| 152 UInt32 code = Code; | |
| 153 UInt32 result = 0; | |
| 154 for (int i = numTotalBits; i != 0; i--) | |
| 155 { | |
| 156 range >>= 1; | |
| 157 /* | |
| 158 result <<= 1; | |
| 159 if (code >= range) | |
| 160 { | |
| 161 code -= range; | |
| 162 result |= 1; | |
| 163 } | |
| 164 */ | |
| 165 UInt32 t = (code - range) >> 31; | |
| 166 code -= range & (t - 1); | |
| 167 result = (result << 1) | (1 - t); | |
| 168 | |
| 169 if (range < kTopValue) | |
| 170 { | |
| 171 code = (code << 8) | Stream.ReadByte(); | |
| 172 range <<= 8; | |
| 173 } | |
| 174 } | |
| 175 Range = range; | |
| 176 Code = code; | |
| 177 return result; | |
| 178 } | |
| 179 | |
| 180 UInt32 DecodeBit(UInt32 size0, UInt32 numTotalBits) | |
| 181 { | |
| 182 UInt32 newBound = (Range >> numTotalBits) * size0; | |
| 183 UInt32 symbol; | |
| 184 if (Code < newBound) | |
| 185 { | |
| 186 symbol = 0; | |
| 187 Range = newBound; | |
| 188 } | |
| 189 else | |
| 190 { | |
| 191 symbol = 1; | |
| 192 Code -= newBound; | |
| 193 Range -= newBound; | |
| 194 } | |
| 195 Normalize(); | |
| 196 return symbol; | |
| 197 } | |
| 198 | |
| 199 UInt64 GetProcessedSize() {return Stream.GetProcessedSize(); } | |
| 200 }; | |
| 201 | |
| 202 }} | |
| 203 | |
| 204 #endif | |
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Chromium Code Reviews
Issue 624713003:
Keep only base/extractor.[cc|h]. (Closed)
Base URL: https://chromium.googlesource.com/external/omaha.git@master