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decoder performance

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This commit is contained in:
Brenschede 2019-06-28 19:07:36 +02:00
parent cfef81322d
commit 7b4db81c78
2 changed files with 58 additions and 12 deletions
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24
brouter-codec/src/main/java/btools/codec/StatCoderContext.java
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@ -9,6 +9,26 @@ public final class StatCoderContext extends BitCoderContext
private static TreeMap<String, long[]> statsPerName;
private long lastbitpos = 0;
private static final int[] noisy_bits = new int[1024];
static
{
// noisybits lookup
for( int i=0; i<1024; i++ )
{
int p = i;
int noisybits = 0;
while (p > 2)
{
noisybits++;
p >>= 1;
}
noisy_bits[i] = noisybits;
}
}
public StatCoderContext( byte[] ab )
{
super( ab );
@ -167,12 +187,12 @@ public final class StatCoderContext extends BitCoderContext
{
int p = predictor < 0 ? -predictor : predictor;
int noisybits = 0;
while (p > 2)
while (p > 1023)
{
noisybits++;
p >>= 1;
}
return predictor + decodeNoisyDiff( noisybits );
return predictor + decodeNoisyDiff( noisybits + noisy_bits[p] );
}
/**