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using System;
namespace SevenZip.Compression.RangeCoder
{
struct BitTreeEncoder
{
BitEncoder[] Models;
int NumBitLevels;
public BitTreeEncoder(int numBitLevels)
{
NumBitLevels = numBitLevels;
Models = new BitEncoder[1 << numBitLevels];
}
public void Init()
{
for (uint i = 1; i < (1 << NumBitLevels); i++)
Models[i].Init();
}
public void Encode(Encoder rangeEncoder, UInt32 symbol)
{
UInt32 m = 1;
for (int bitIndex = NumBitLevels; bitIndex > 0; )
{
bitIndex--;
UInt32 bit = (symbol >> bitIndex) & 1;
Models[m].Encode(rangeEncoder, bit);
m = (m << 1) | bit;
}
}
public void ReverseEncode(Encoder rangeEncoder, UInt32 symbol)
{
UInt32 m = 1;
for (UInt32 i = 0; i < NumBitLevels; i++)
{
UInt32 bit = symbol & 1;
Models[m].Encode(rangeEncoder, bit);
m = (m << 1) | bit;
symbol >>= 1;
}
}
public UInt32 GetPrice(UInt32 symbol)
{
UInt32 price = 0;
UInt32 m = 1;
for (int bitIndex = NumBitLevels; bitIndex > 0; )
{
bitIndex--;
UInt32 bit = (symbol >> bitIndex) & 1;
price += Models[m].GetPrice(bit);
m = (m << 1) + bit;
}
return price;
}
public UInt32 ReverseGetPrice(UInt32 symbol)
{
UInt32 price = 0;
UInt32 m = 1;
for (int i = NumBitLevels; i > 0; i--)
{
UInt32 bit = symbol & 1;
symbol >>= 1;
price += Models[m].GetPrice(bit);
m = (m << 1) | bit;
}
return price;
}
public static UInt32 ReverseGetPrice(BitEncoder[] Models, UInt32 startIndex,
int NumBitLevels, UInt32 symbol)
{
UInt32 price = 0;
UInt32 m = 1;
for (int i = NumBitLevels; i > 0; i--)
{
UInt32 bit = symbol & 1;
symbol >>= 1;
price += Models[startIndex + m].GetPrice(bit);
m = (m << 1) | bit;
}
return price;
}
public static void ReverseEncode(BitEncoder[] Models, UInt32 startIndex,
Encoder rangeEncoder, int NumBitLevels, UInt32 symbol)
{
UInt32 m = 1;
for (int i = 0; i < NumBitLevels; i++)
{
UInt32 bit = symbol & 1;
Models[startIndex + m].Encode(rangeEncoder, bit);
m = (m << 1) | bit;
symbol >>= 1;
}
}
}
struct BitTreeDecoder
{
BitDecoder[] Models;
int NumBitLevels;
public BitTreeDecoder(int numBitLevels)
{
NumBitLevels = numBitLevels;
Models = new BitDecoder[1 << numBitLevels];
}
public void Init()
{
for (uint i = 1; i < (1 << NumBitLevels); i++)
Models[i].Init();
}
public uint Decode(RangeCoder.Decoder rangeDecoder)
{
uint m = 1;
for (int bitIndex = NumBitLevels; bitIndex > 0; bitIndex--)
m = (m << 1) + Models[m].Decode(rangeDecoder);
return m - ((uint)1 << NumBitLevels);
}
public uint ReverseDecode(RangeCoder.Decoder rangeDecoder)
{
uint m = 1;
uint symbol = 0;
for (int bitIndex = 0; bitIndex < NumBitLevels; bitIndex++)
{
uint bit = Models[m].Decode(rangeDecoder);
m <<= 1;
m += bit;
symbol |= (bit << bitIndex);
}
return symbol;
}
public static uint ReverseDecode(BitDecoder[] Models, UInt32 startIndex,
RangeCoder.Decoder rangeDecoder, int NumBitLevels)
{
uint m = 1;
uint symbol = 0;
for (int bitIndex = 0; bitIndex < NumBitLevels; bitIndex++)
{
uint bit = Models[startIndex + m].Decode(rangeDecoder);
m <<= 1;
m += bit;
symbol |= (bit << bitIndex);
}
return symbol;
}
}
}
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