1 files changed, 117 insertions, 0 deletions
diff --git a/other-licenses/7zstub/src/CS/7zip/Compress/RangeCoder/RangeCoderBit.cs b/other-licenses/7zstub/src/CS/7zip/Compress/RangeCoder/RangeCoderBit.cs
new file mode 100644
index 0000000000..000a5a0787
--- /dev/null
+++ b/other-licenses/7zstub/src/CS/7zip/Compress/RangeCoder/RangeCoderBit.cs
@@ -0,0 +1,117 @@
+using System;
+
+namespace SevenZip.Compression.RangeCoder
+{
+	struct BitEncoder
+	{
+		public const int kNumBitModelTotalBits = 11;
+		public const uint kBitModelTotal = (1 << kNumBitModelTotalBits);
+		const int kNumMoveBits = 5;
+		const int kNumMoveReducingBits = 2;
+		public const int kNumBitPriceShiftBits = 6;
+
+		uint Prob;
+
+		public void Init() { Prob = kBitModelTotal >> 1; }
+
+		public void UpdateModel(uint symbol)
+		{
+			if (symbol == 0)
+				Prob += (kBitModelTotal - Prob) >> kNumMoveBits;
+			else
+				Prob -= (Prob) >> kNumMoveBits;
+		}
+
+		public void Encode(Encoder encoder, uint symbol)
+		{
+			// encoder.EncodeBit(Prob, kNumBitModelTotalBits, symbol);
+			// UpdateModel(symbol);
+			uint newBound = (encoder.Range >> kNumBitModelTotalBits) * Prob;
+			if (symbol == 0)
+			{
+				encoder.Range = newBound;
+				Prob += (kBitModelTotal - Prob) >> kNumMoveBits;
+			}
+			else
+			{
+				encoder.Low += newBound;
+				encoder.Range -= newBound;
+				Prob -= (Prob) >> kNumMoveBits;
+			}
+			if (encoder.Range < Encoder.kTopValue)
+			{
+				encoder.Range <<= 8;
+				encoder.ShiftLow();
+			}
+		}
+
+		private static UInt32[] ProbPrices = new UInt32[kBitModelTotal >> kNumMoveReducingBits];
+
+		static BitEncoder()
+		{
+			const int kNumBits = (kNumBitModelTotalBits - kNumMoveReducingBits);
+			for (int i = kNumBits - 1; i >= 0; i--)
+			{
+				UInt32 start = (UInt32)1 << (kNumBits - i - 1);
+				UInt32 end = (UInt32)1 << (kNumBits - i);
+				for (UInt32 j = start; j < end; j++)
+					ProbPrices[j] = ((UInt32)i << kNumBitPriceShiftBits) +
+						(((end - j) << kNumBitPriceShiftBits) >> (kNumBits - i - 1));
+			}
+		}
+
+		public uint GetPrice(uint symbol)
+		{
+			return ProbPrices[(((Prob - symbol) ^ ((-(int)symbol))) & (kBitModelTotal - 1)) >> kNumMoveReducingBits];
+		}
+	  public uint GetPrice0() { return ProbPrices[Prob >> kNumMoveReducingBits]; }
+		public uint GetPrice1() { return ProbPrices[(kBitModelTotal - Prob) >> kNumMoveReducingBits]; }
+	}
+
+	struct BitDecoder
+	{
+		public const int kNumBitModelTotalBits = 11;
+		public const uint kBitModelTotal = (1 << kNumBitModelTotalBits);
+		const int kNumMoveBits = 5;
+
+		uint Prob;
+
+		public void UpdateModel(int numMoveBits, uint symbol)
+		{
+			if (symbol == 0)
+				Prob += (kBitModelTotal - Prob) >> numMoveBits;
+			else
+				Prob -= (Prob) >> numMoveBits;
+		}
+
+		public void Init() { Prob = kBitModelTotal >> 1; }
+
+		public uint Decode(RangeCoder.Decoder rangeDecoder)
+		{
+			uint newBound = (uint)(rangeDecoder.Range >> kNumBitModelTotalBits) * (uint)Prob;
+			if (rangeDecoder.Code < newBound)
+			{
+				rangeDecoder.Range = newBound;
+				Prob += (kBitModelTotal - Prob) >> kNumMoveBits;
+				if (rangeDecoder.Range < Decoder.kTopValue)
+				{
+					rangeDecoder.Code = (rangeDecoder.Code << 8) | (byte)rangeDecoder.Stream.ReadByte();
+					rangeDecoder.Range <<= 8;
+				}
+				return 0;
+			}
+			else
+			{
+				rangeDecoder.Range -= newBound;
+				rangeDecoder.Code -= newBound;
+				Prob -= (Prob) >> kNumMoveBits;
+				if (rangeDecoder.Range < Decoder.kTopValue)
+				{
+					rangeDecoder.Code = (rangeDecoder.Code << 8) | (byte)rangeDecoder.Stream.ReadByte();
+					rangeDecoder.Range <<= 8;
+				}
+				return 1;
+			}
+		}
+	}
+}