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package SevenZip.Compression.RangeCoder;↩
import java.io.IOException;↩
↩
public class Decoder↩
{↩
static final int kTopMask = ~((1 << 24) - 1);↩
↩
static final int kNumBitModelTotalBits = 11;↩
static final int kBitModelTotal = (1 << kNumBitModelTotalBits);↩
static final int kNumMoveBits = 5;↩
↩
int Range;↩
int Code;↩
↩
java.io.InputStream Stream;↩
↩
public final void SetStream(java.io.InputStream stream)↩
{ ↩
Stream = stream; ↩
}↩
↩
public final void ReleaseStream()↩
{ ↩
Stream = null; ↩
}↩
↩
public final void Init() throws IOException↩
{↩
Code = 0;↩
Range = -1;↩
for (int i = 0; i < 5; i++)↩
Code = (Code << 8) | Stream.read();↩
}↩
↩
public final int DecodeDirectBits(int numTotalBits) throws IOException↩
{↩
int result = 0;↩
for (int i = numTotalBits; i != 0; i--)↩
{↩
Range >>>= 1;↩
int t = ((Code - Range) >>> 31);↩
Code -= Range & (t - 1);↩
result = (result << 1) | (1 - t);↩
↩
if ((Range & kTopMask) == 0)↩
{↩
Code = (Code << 8) | Stream.read();↩
Range <<= 8;↩
}↩
}↩
return result;↩
}↩
↩
public int DecodeBit(short []probs, int index) throws IOException↩
{↩
int prob = probs[index];↩
int newBound = (Range >>> kNumBitModelTotalBits) * prob;↩
if ((Code ^ 0x80000000) < (newBound ^ 0x80000000))↩
{↩
Range = newBound;↩
probs[index] = (short)(prob + ((kBitModelTotal - prob) >>> kNumMoveBits));↩
if ((Range & kTopMask) == 0)↩
{↩
Code = (Code << 8) | Stream.read();↩
Range <<= 8;↩
}↩
return 0;↩
}↩
else↩
{↩
Range -= newBound;↩
Code -= newBound;↩
probs[index] = (short)(prob - ((prob) >>> kNumMoveBits));↩
if ((Range & kTopMask) == 0)↩
{↩
Code = (Code << 8) | Stream.read();↩
Range <<= 8;↩
}↩
return 1;↩
}↩
}↩
↩
public static void InitBitModels(short []probs)↩
{↩
for (int i = 0; i < probs.length; i++)↩
probs[i] = (kBitModelTotal >>> 1);↩
}↩
}↩