Keep only base/extractor.[cc|h].

third_party/lzma/v4_65/files/Java/SevenZip/Compression/RangeCoder/BitTreeDecoder.java

-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;
-        }
-}