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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);
}
}
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