Add LZMA.

3rdparty/lzma-21.03beta/Java/SevenZip/Compression/RangeCoder/BitTreeDecoder.java

@@ -0,0 +1,55 @@
+package SevenZip.Compression.RangeCoder;
+
+public class BitTreeDecoder
+{
+	short[] Models;
+	int NumBitLevels;
+	
+	public BitTreeDecoder(int numBitLevels)
+	{
+		NumBitLevels = numBitLevels;
+		Models = new short[1 << numBitLevels];
+	}
+	
+	public void Init()
+	{
+		Decoder.InitBitModels(Models);
+	}
+	
+	public int Decode(Decoder rangeDecoder) throws java.io.IOException
+	{
+		int m = 1;
+		for (int bitIndex = NumBitLevels; bitIndex != 0; bitIndex--)
+			m = (m << 1) + rangeDecoder.DecodeBit(Models, m);
+		return m - (1 << NumBitLevels);
+	}
+	
+	public int ReverseDecode(Decoder rangeDecoder) throws java.io.IOException
+	{
+		int m = 1;
+		int symbol = 0;
+		for (int bitIndex = 0; bitIndex < NumBitLevels; bitIndex++)
+		{
+			int bit = rangeDecoder.DecodeBit(Models, m);
+			m <<= 1;
+			m += bit;
+			symbol |= (bit << bitIndex);
+		}
+		return symbol;
+	}
+	
+	public static int ReverseDecode(short[] Models, int startIndex,
+			Decoder rangeDecoder, int NumBitLevels) throws java.io.IOException
+	{
+		int m = 1;
+		int symbol = 0;
+		for (int bitIndex = 0; bitIndex < NumBitLevels; bitIndex++)
+		{
+			int bit = rangeDecoder.DecodeBit(Models, startIndex + m);
+			m <<= 1;
+			m += bit;
+			symbol |= (bit << bitIndex);
+		}
+		return symbol;
+	}
+}