summaryrefslogtreecommitdiffstats
path: root/other-licenses/7zstub/src/7zip/Compress/RangeCoder/RangeCoderBit.h
diff options
context:
space:
mode:
Diffstat (limited to 'other-licenses/7zstub/src/7zip/Compress/RangeCoder/RangeCoderBit.h')
-rw-r--r--other-licenses/7zstub/src/7zip/Compress/RangeCoder/RangeCoderBit.h120
1 files changed, 120 insertions, 0 deletions
diff --git a/other-licenses/7zstub/src/7zip/Compress/RangeCoder/RangeCoderBit.h b/other-licenses/7zstub/src/7zip/Compress/RangeCoder/RangeCoderBit.h
new file mode 100644
index 000000000..64538e687
--- /dev/null
+++ b/other-licenses/7zstub/src/7zip/Compress/RangeCoder/RangeCoderBit.h
@@ -0,0 +1,120 @@
+// Compress/RangeCoder/RangeCoderBit.h
+
+#ifndef __COMPRESS_RANGECODER_BIT_H
+#define __COMPRESS_RANGECODER_BIT_H
+
+#include "RangeCoder.h"
+
+namespace NCompress {
+namespace NRangeCoder {
+
+const int kNumBitModelTotalBits = 11;
+const UInt32 kBitModelTotal = (1 << kNumBitModelTotalBits);
+
+const int kNumMoveReducingBits = 2;
+
+const int kNumBitPriceShiftBits = 6;
+const UInt32 kBitPrice = 1 << kNumBitPriceShiftBits;
+
+class CPriceTables
+{
+public:
+ static UInt32 ProbPrices[kBitModelTotal >> kNumMoveReducingBits];
+ static void Init();
+ CPriceTables();
+};
+
+template <int numMoveBits>
+class CBitModel
+{
+public:
+ UInt32 Prob;
+ void UpdateModel(UInt32 symbol)
+ {
+ /*
+ Prob -= (Prob + ((symbol - 1) & ((1 << numMoveBits) - 1))) >> numMoveBits;
+ Prob += (1 - symbol) << (kNumBitModelTotalBits - numMoveBits);
+ */
+ if (symbol == 0)
+ Prob += (kBitModelTotal - Prob) >> numMoveBits;
+ else
+ Prob -= (Prob) >> numMoveBits;
+ }
+public:
+ void Init() { Prob = kBitModelTotal / 2; }
+};
+
+template <int numMoveBits>
+class CBitEncoder: public CBitModel<numMoveBits>
+{
+public:
+ void Encode(CEncoder *encoder, UInt32 symbol)
+ {
+ /*
+ encoder->EncodeBit(this->Prob, kNumBitModelTotalBits, symbol);
+ this->UpdateModel(symbol);
+ */
+ UInt32 newBound = (encoder->Range >> kNumBitModelTotalBits) * this->Prob;
+ if (symbol == 0)
+ {
+ encoder->Range = newBound;
+ this->Prob += (kBitModelTotal - this->Prob) >> numMoveBits;
+ }
+ else
+ {
+ encoder->Low += newBound;
+ encoder->Range -= newBound;
+ this->Prob -= (this->Prob) >> numMoveBits;
+ }
+ if (encoder->Range < kTopValue)
+ {
+ encoder->Range <<= 8;
+ encoder->ShiftLow();
+ }
+ }
+ UInt32 GetPrice(UInt32 symbol) const
+ {
+ return CPriceTables::ProbPrices[
+ (((this->Prob - symbol) ^ ((-(int)symbol))) & (kBitModelTotal - 1)) >> kNumMoveReducingBits];
+ }
+ UInt32 GetPrice0() const { return CPriceTables::ProbPrices[this->Prob >> kNumMoveReducingBits]; }
+ UInt32 GetPrice1() const { return CPriceTables::ProbPrices[(kBitModelTotal - this->Prob) >> kNumMoveReducingBits]; }
+};
+
+
+template <int numMoveBits>
+class CBitDecoder: public CBitModel<numMoveBits>
+{
+public:
+ UInt32 Decode(CDecoder *decoder)
+ {
+ UInt32 newBound = (decoder->Range >> kNumBitModelTotalBits) * this->Prob;
+ if (decoder->Code < newBound)
+ {
+ decoder->Range = newBound;
+ this->Prob += (kBitModelTotal - this->Prob) >> numMoveBits;
+ if (decoder->Range < kTopValue)
+ {
+ decoder->Code = (decoder->Code << 8) | decoder->Stream.ReadByte();
+ decoder->Range <<= 8;
+ }
+ return 0;
+ }
+ else
+ {
+ decoder->Range -= newBound;
+ decoder->Code -= newBound;
+ this->Prob -= (this->Prob) >> numMoveBits;
+ if (decoder->Range < kTopValue)
+ {
+ decoder->Code = (decoder->Code << 8) | decoder->Stream.ReadByte();
+ decoder->Range <<= 8;
+ }
+ return 1;
+ }
+ }
+};
+
+}}
+
+#endif