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statistical encoding

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This commit is contained in:
Arndt 2015-10-11 19:27:33 +02:00
parent f8dee5b7d1
commit ccf6641bad
41 changed files with 4543 additions and 1965 deletions
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61
brouter-util/src/main/java/btools/util/ByteArrayUnifier.java
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@ -9,11 +9,7 @@ public final class ByteArrayUnifier
public ByteArrayUnifier( int size, boolean validateImmutability )
{
this.size = size;
if ( !Boolean.getBoolean( "disableByteArrayUnifification" ) )
{
byteArrayCache = new byte[size][];
}
byteArrayCache = new byte[size][];
if ( validateImmutability ) crcCrosscheck = new int[size];
}
@ -26,33 +22,40 @@ public final class ByteArrayUnifier
*/
public byte[] unify( byte[] ab )
{
if ( byteArrayCache == null ) return ab;
int n = ab.length;
int crc = Crc32.crc( ab, 0, n );
int idx = (crc & 0xfffffff) % size;
byte[] abc = byteArrayCache[idx];
if ( abc != null && abc.length == n )
return unify( ab, 0, ab.length );
}
public byte[] unify( byte[] ab, int offset, int len )
{
int crc = Crc32.crc( ab, offset, len );
int idx = ( crc & 0xfffffff ) % size;
byte[] abc = byteArrayCache[idx];
if ( abc != null && abc.length == len )
{
int i = 0;
while (i < len)
{
int i = 0;
while( i < n )
{
if ( ab[i] != abc[i] ) break;
i++;
}
if ( i == n ) return abc;
if ( ab[offset + i] != abc[i] )
break;
i++;
}
if ( crcCrosscheck != null )
if ( i == len )
return abc;
}
if ( crcCrosscheck != null )
{
if ( byteArrayCache[idx] != null )
{
if ( byteArrayCache[idx] != null )
{
byte[] abold = byteArrayCache[idx];
int crcold = Crc32.crc( abold, 0, abold.length );
if ( crcold != crcCrosscheck[idx] ) throw new IllegalArgumentException( "ByteArrayUnifier: immutablity validation failed!" );
}
crcCrosscheck[idx] = crc;
byte[] abold = byteArrayCache[idx];
int crcold = Crc32.crc( abold, 0, abold.length );
if ( crcold != crcCrosscheck[idx] )
throw new IllegalArgumentException( "ByteArrayUnifier: immutablity validation failed!" );
}
byteArrayCache[idx] = ab;
return ab;
crcCrosscheck[idx] = crc;
}
byte[] nab = new byte[len];
System.arraycopy( ab, offset, nab, 0, len );
byteArrayCache[idx] = nab;
return nab;
}
}