1 package SevenZip.Compression.RangeCoder;

     2 import java.io.IOException;

     3 

     4 public class BitTreeEncoder

     5 {

     6 	short[] Models;

     7 	int NumBitLevels;

     8 	

     9 	public BitTreeEncoder(int numBitLevels)

    10 	{

    11 		NumBitLevels = numBitLevels;

    12 		Models = new short[1 << numBitLevels];

    13 	}

    14 	

    15 	public void Init()

    16 	{

    17 		Decoder.InitBitModels(Models);

    18 	}

    19 	

    20 	public void Encode(Encoder rangeEncoder, int symbol) throws IOException

    21 	{

    22 		int m = 1;

    23 		for (int bitIndex = NumBitLevels; bitIndex != 0; )

    24 		{

    25 			bitIndex--;

    26 			int bit = (symbol >>> bitIndex) & 1;

    27 			rangeEncoder.Encode(Models, m, bit);

    28 			m = (m << 1) | bit;

    29 		}

    30 	}

    31 	

    32 	public void ReverseEncode(Encoder rangeEncoder, int symbol) throws IOException

    33 	{

    34 		int m = 1;

    35 		for (int  i = 0; i < NumBitLevels; i++)

    36 		{

    37 			int bit = symbol & 1;

    38 			rangeEncoder.Encode(Models, m, bit);

    39 			m = (m << 1) | bit;

    40 			symbol >>= 1;

    41 		}

    42 	}

    43 	

    44 	public int GetPrice(int symbol)

    45 	{

    46 		int price = 0;

    47 		int m = 1;

    48 		for (int bitIndex = NumBitLevels; bitIndex != 0; )

    49 		{

    50 			bitIndex--;

    51 			int bit = (symbol >>> bitIndex) & 1;

    52 			price += Encoder.GetPrice(Models[m], bit);

    53 			m = (m << 1) + bit;

    54 		}

    55 		return price;

    56 	}

    57 	

    58 	public int ReverseGetPrice(int symbol)

    59 	{

    60 		int price = 0;

    61 		int m = 1;

    62 		for (int i = NumBitLevels; i != 0; i--)

    63 		{

    64 			int bit = symbol & 1;

    65 			symbol >>>= 1;

    66 			price += Encoder.GetPrice(Models[m], bit);

    67 			m = (m << 1) | bit;

    68 		}

    69 		return price;

    70 	}

    71 	

    72 	public static int ReverseGetPrice(short[] Models, int startIndex,

    73 			int NumBitLevels, int symbol)

    74 	{

    75 		int price = 0;

    76 		int m = 1;

    77 		for (int i = NumBitLevels; i != 0; i--)

    78 		{

    79 			int bit = symbol & 1;

    80 			symbol >>>= 1;

    81 			price += Encoder.GetPrice(Models[startIndex + m], bit);

    82 			m = (m << 1) | bit;

    83 		}

    84 		return price;

    85 	}

    86 	

    87 	public static void ReverseEncode(short[] Models, int startIndex,

    88 			Encoder rangeEncoder, int NumBitLevels, int symbol) throws IOException

    89 	{

    90 		int m = 1;

    91 		for (int i = 0; i < NumBitLevels; i++)

    92 		{

    93 			int bit = symbol & 1;

    94 			rangeEncoder.Encode(Models, startIndex + m, bit);

    95 			m = (m << 1) | bit;

    96 			symbol >>= 1;

    97 		}

    98 	}

    99 }