some more cleanup and performance squeezing

brouter-codec/src/main/java/btools/codec/StatCoderContext.java

@@ -22,7 +22,7 @@ public final class StatCoderContext extends BitCoderContext
    */
   public void assignBits( String name )
   {
-    long bitpos = getBitPosition();
+    long bitpos = getWritingBitPosition();
     if ( statsPerName == null )
     {
       statsPerName = new TreeMap<String, long[]>();
@@ -88,12 +88,7 @@ public final class StatCoderContext extends BitCoderContext
    */
   public int decodeNoisyNumber( int noisybits )
   {
-    int value = 0;
+    int value = decodeBits( noisybits );
-    if ( noisybits > 0 )
-    {
-      int mask = 0xffffffff >>> ( 32 - noisybits );
-      value = decodeBounded( mask );
-    }
     return value | ( decodeVarBits() << noisybits );
   }
 
@@ -130,8 +125,7 @@ public final class StatCoderContext extends BitCoderContext
     int value = 0;
     if ( noisybits > 0 )
     {
-      int mask = 0xffffffff >>> ( 32 - noisybits );
+      value = decodeBits( noisybits ) - ( 1 << ( noisybits - 1 ) );
-      value = decodeBounded( mask ) - ( 1 << ( noisybits - 1 ) );
     }
     int val2 = decodeVarBits() << noisybits;
     if ( val2 != 0 )

brouter-codec/src/main/java/btools/codec/TagValueCoder.java

@@ -99,26 +99,33 @@ public final class TagValueCoder
       node.child2 = decodeTree( bc, buffer, validator );
       return node;
     }
-    BitCoderContext target = null;
+    int startpos = bc.getReadingBitPosition();
+    boolean hasdata = false;
     for ( ;; )
     {
       int delta = bc.decodeVarBits();
-      if ( target == null )
+      if ( !hasdata )
       {
         if ( delta == 0 )
+        {
           return null;
-        target = new BitCoderContext( buffer );
+        }
-        target.encodeBit( false ); // dummy reverse bit
+        hasdata = true;
       }
-      target.encodeVarBits( delta );
       if ( delta == 0 )
+      {
         break;
-      int data = bc.decodeVarBits();
+      }
-      target.encodeVarBits( data );
+      bc.decodeVarBits();
     }
-    int len = target.getEncodedLength();
+    int endpos = bc.getReadingBitPosition();
-    byte[] res = new byte[len];
+    
-    System.arraycopy( buffer, 0, res, 0, len );
+    int bitcount = endpos - startpos;
+    int bytecount = ( bitcount + 7 ) >> 3;
+
+    bc.setReadingBitPosition( startpos );
+    byte[] res = new byte[bytecount];
+    bc.copyBitsTo( res, bitcount );
 
     int accessType = validator == null ? 2 : validator.accessType( res );
     if ( accessType > 0 )
@@ -165,10 +172,6 @@ public final class TagValueCoder
           return;
         }
         BitCoderContext src = new BitCoderContext( data );
-        if ( src.decodeBit() )
-        {
-          throw new IllegalArgumentException( "cannot encode reverse bit!" );
-        }
         for ( ;; )
         {
           int delta = src.decodeVarBits();

brouter-core/src/main/java/btools/router/OsmPath.java

@@ -47,7 +47,7 @@ final class OsmPath implements OsmLinkHolder
   public int originLon;
   public int originLat;
 
-  // the costfactor of the segment just before this paths position
+  // the classifier of the segment just before this paths position
   public float lastClassifier;
 
   public MessageData message;
@@ -129,6 +129,37 @@ final class OsmPath implements OsmLinkHolder
 
     MessageData msgData = recordMessageData ? new MessageData() : null;
 
+    // evaluate the way tags
+    rc.expctxWay.evaluate( rc.inverseDirection ^ link.counterLinkWritten, description );
+
+    // calculate the costfactor inputs
+    boolean isTrafficBackbone = cost == 0 && rc.expctxWay.getIsTrafficBackbone() > 0.f;
+    float turncostbase = rc.expctxWay.getTurncost();
+    float cfup = rc.expctxWay.getUphillCostfactor();
+    float cfdown = rc.expctxWay.getDownhillCostfactor();
+    float cf = rc.expctxWay.getCostfactor();
+    cfup = cfup == 0.f ? cf : cfup;
+    cfdown = cfdown == 0.f ? cf : cfdown;
+
+    // *** add initial cost if the classifier changed
+    float newClassifier = rc.expctxWay.getInitialClassifier();
+    if ( newClassifier == 0. )
+    {
+      newClassifier = (cfup + cfdown + cf)/3;
+    }
+    float classifierDiff = newClassifier - lastClassifier;
+    if ( classifierDiff > 0.0005 || classifierDiff < -0.0005 )
+    {
+      lastClassifier = newClassifier;
+      float initialcost = rc.expctxWay.getInitialcost();
+      int iicost = (int)initialcost;
+      if ( recordMessageData )
+      {
+        msgData.linkinitcost += iicost;
+      }
+      cost += iicost;
+    }
+
     OsmTransferNode transferNode = link.decodeFirsttransfer( p1 );
     OsmNode targetNode = link.targetNode;
     for(;;)
@@ -152,10 +183,8 @@ final class OsmPath implements OsmLinkHolder
         lat2 = transferNode.ilat;
         ele2 = transferNode.selev;
       }
-
-      boolean sameData = rc.expctxWay.evaluate( rc.inverseDirection ^ link.counterLinkWritten, description );
       
-      // if way description changed, store message
+      // if recording, new MessageData for each section (needed for turn-instructions)
       if ( recordMessageData && msgData.wayKeyValues != null )
       {
         originElement.message = msgData;
@@ -199,18 +228,16 @@ final class OsmPath implements OsmLinkHolder
       }
       linkdisttotal += dist;
 
-      boolean isTrafficBackbone = cost == 0 && rc.expctxWay.getIsTrafficBackbone() > 0.f;
-
       // *** penalty for turning angles
       if ( !isTrafficBackbone && origin.originElement != null )
       {
         // penalty proportional to direction change
         double cos = rc.calcCosAngle( lon0, lat0, lon1, lat1, lon2, lat2 );
-        int turncost = (int)(cos * rc.expctxWay.getTurncost() + 0.2 ); // e.g. turncost=90 -> 90 degree = 90m penalty
+        int actualturncost = (int)(cos * turncostbase + 0.2 ); // e.g. turncost=90 -> 90 degree = 90m penalty
-        cost += turncost;
+        cost += actualturncost;
         if ( recordMessageData )
         {
-          msgData.linkturncost += turncost;
+          msgData.linkturncost += actualturncost;
           msgData.turnangle = (float)rc.calcAngle( lon0, lat0, lon1, lat1, lon2, lat2 );
         }
       }
@@ -292,16 +319,8 @@ final class OsmPath implements OsmLinkHolder
         ehbu = 0;
       }
 
-      // *** penalty for distance
+      // get the effective costfactor (slope dependent)
-      float cfup = rc.expctxWay.getUphillCostfactor();
-      float cfdown = rc.expctxWay.getDownhillCostfactor();
-      float cf = rc.expctxWay.getCostfactor();
-
-      cfup = cfup == 0.f ? cf : cfup;
-      cfdown = cfdown == 0.f ? cf : cfdown;
-      
       float costfactor = cfup*upweight + cf*(1.f - upweight - downweight) + cfdown*downweight;
-
       if ( isTrafficBackbone )
       {
         costfactor = 0.f;
@@ -323,24 +342,6 @@ final class OsmPath implements OsmLinkHolder
         int cost2 = cost < minDist ? minDist : cost;
         traffic += dist*rc.expctxWay.getTrafficSourceDensity()*Math.pow(cost2/10000.f,rc.trafficSourceExponent);
       }
-      // *** add initial cost if the classifier changed
-      float newClassifier = rc.expctxWay.getInitialClassifier();
-      if ( newClassifier == 0. )
-      {
-        newClassifier = (cfup + cfdown + cf)/3;
-      }
-      float classifierDiff = newClassifier - lastClassifier;
-      if ( classifierDiff > 0.0005 || classifierDiff < -0.0005 )
-      {
-          lastClassifier = newClassifier;
-          float initialcost = rc.expctxWay.getInitialcost();
-          int iicost = (int)initialcost;
-          if ( recordMessageData )
-          {
-            msgData.linkinitcost += iicost;
-          }
-          cost += iicost;
-      }
 
       if ( recordMessageData )
       {

brouter-core/src/main/java/btools/router/ProfileCache.java

@@ -63,8 +63,8 @@ public final class ProfileCache
       BExpressionMetaData meta = new BExpressionMetaData();
       
       BExpressionContextGlobal expctxGlobal = new BExpressionContextGlobal( meta );
-      rc.expctxWay = new BExpressionContextWay( rc.serversizing ? 262144 : 8192, meta );
+      rc.expctxWay = new BExpressionContextWay( rc.serversizing ? 262144 : 32768, meta );
-      rc.expctxNode = new BExpressionContextNode( rc.serversizing ?  16384 : 2048, meta );
+      rc.expctxNode = new BExpressionContextNode( rc.serversizing ?  16384 : 4096, meta );
       
       meta.readMetaData( new File( profileDir, "lookups.dat" ) );
 

brouter-core/src/main/java/btools/router/RoutingContext.java

@@ -12,10 +12,8 @@ import java.util.List;
 import btools.expressions.BExpressionContext;
 import btools.expressions.BExpressionContextNode;
 import btools.expressions.BExpressionContextWay;
-import btools.mapaccess.DistanceChecker;
-import btools.mapaccess.OsmTransferNode;
 
-public final class RoutingContext implements DistanceChecker
+public final class RoutingContext
 {
   public void setAlternativeIdx( int idx )
   {
@@ -349,28 +347,4 @@ public final class RoutingContext implements DistanceChecker
     return p;
   }
 
-  @Override
-  public boolean isWithinRadius( int ilon0, int ilat0, OsmTransferNode firstTransfer, int ilon1, int ilat1 )
-  {
-    OsmNodeNamed wp = nogopoints.get(0);
-    double keepRadius = wp.radius;
-    try
-    {
-      int ilon = ilon0;
-      int ilat = ilat0;
-      for( OsmTransferNode trans = firstTransfer; trans != null; trans = trans.next )
-      {
-        calcDistance( ilon, ilat, trans.ilon, trans.ilat );
-        ilon = trans.ilon;
-        ilat = trans.ilat;
-      }
-      calcDistance( ilon, ilat, ilon1, ilat1 );
-      return wp.radius < keepRadius;
-    }
-    finally
-    {
-      wp.radius = keepRadius;
-    }
-  }
-
 }

brouter-core/src/main/java/btools/router/RoutingEngine.java

@@ -226,10 +226,19 @@ public class RoutingEngine extends Thread
     }
     finally
     {
-      ProfileCache.releaseProfile( routingContext );
+      if ( hasInfo() && routingContext.expctxWay != null )
+      {
+        logInfo( "expression cache stats=" + routingContext.expctxWay.cacheStats() );
+      }
 
+      ProfileCache.releaseProfile( routingContext );
+      
       if ( nodesCache != null )
       {
+        if ( hasInfo() && nodesCache != null )
+        {
+          logInfo( "NodesCache status before close=" + nodesCache.formatStatus() );
+        }
         nodesCache.close();
         nodesCache = null;
       }
@@ -544,6 +553,10 @@ public class RoutingEngine extends Thread
 
   private void resetCache()
   {
+    if ( hasInfo() && nodesCache != null )
+    {
+      logInfo( "NodesCache status before reset=" + nodesCache.formatStatus() );
+    }
     nodesMap = new OsmNodesMap();
     nodesCache = new NodesCache(segmentDir, nodesMap, routingContext.expctxWay, routingContext.carMode, routingContext.forceSecondaryData, nodesCache );
   }

brouter-expressions/src/main/java/btools/expressions/BExpressionContext.java

@@ -49,12 +49,9 @@ public abstract class BExpressionContext
 
   // hash-cache for function results
   private byte[][] _arrayBitmap;
-  private boolean[] _arrayInverse;
   private int[] _arrayCrc;
 
   private int currentHashBucket = -1;
-  private byte[] currentByteArray = null;
-  private boolean currentInverseDirection= false;
 
   private List<BExpression> expressionList;
 
@@ -98,17 +95,10 @@ public abstract class BExpressionContext
 
      if ( Boolean.getBoolean( "disableExpressionCache" ) ) hashSize = 1;
       
+     // create the expression cache
      _arrayBitmap = new byte[hashSize][];
-     _arrayInverse = new boolean[hashSize];
      _arrayCrc = new int[hashSize];
-
-     // create the build-in variables cache     
-     int nBuildInVars = getBuildInVariableNames().length;
      arrayBuildInVariablesCache = new float[hashSize][];
-     for( int hi=0; hi<hashSize; hi++ )
-     {
-       arrayBuildInVariablesCache[hi] = new float[nBuildInVars];
-     }
   }
 
   /**
@@ -124,7 +114,6 @@ public abstract class BExpressionContext
   {
 	// start with first bit hardwired ("reversedirection")
 	BitCoderContext ctx = new BitCoderContext( abBuf );
-	ctx.encodeBit( ld[0] != 0 );
 	
 	int skippedTags = 0;
 	int nonNullTags= 0;
@@ -159,7 +148,7 @@ public abstract class BExpressionContext
     // crosscheck: decode and compare
     int[] ld2 = new int[lookupValues.size()];
     decode( ld2, false, ab );
-    for( int inum = 0; inum < lookupValues.size(); inum++ ) // loop over lookup names
+    for( int inum = 1; inum < lookupValues.size(); inum++ ) // loop over lookup names (except reverse dir)
     {
       if ( ld2[inum] != ld[inum] ) throw new RuntimeException( "assertion failed encoding inum=" + inum + " val=" + ld[inum] + " " + getKeyValueDescription(false, ab) );
     }    
@@ -185,7 +174,7 @@ public abstract class BExpressionContext
     BitCoderContext ctx = new BitCoderContext(ab);
 	  
     // start with first bit hardwired ("reversedirection")
-  	ld[0] = inverseDirection ^ ctx.decodeBit() ? 2 : 0;
+    ld[0] = inverseDirection ? 2 : 0;
   	
     // all others are generic
   	int inum = 1;
@@ -270,72 +259,80 @@ public abstract class BExpressionContext
     }
   }
 
-  public long requests;
+  private long requests;
-  public long requests2;
+  private long requests2;
-  public long cachemisses;
+  private long cachemisses;
+  
+  public String cacheStats()
+  {
+    return "requests=" + requests + " requests2=" + requests2 + " cachemisses=" + cachemisses;
+  }
 
   /**
    * evaluates the data in the given byte array
    * 
    * @return true if the data is equivilant to the last calls data
    */
-  public boolean evaluate( boolean inverseDirection, byte[] ab )
+  public void evaluate( boolean inverseDirection, byte[] ab )
   {
-	 requests ++;
+    requests++;
-	 lookupDataValid = false; // this is an assertion for a nasty pifall
+    lookupDataValid = false; // this is an assertion for a nasty pifall
 
-	 int inverseBitByteIndex = 0;
+    // calc hash bucket from crc
+    int crc = Crc32.crcWithInverseBit( ab, inverseDirection );
+    int hashSize = _arrayBitmap.length;
+    currentHashBucket = ( crc & 0xfffffff ) % hashSize;
+    
+    int nBuildInVars = buildInVariableIdx.length;
+    hashBucketVars = arrayBuildInVariablesCache[currentHashBucket];
+    if ( hashBucketVars == null )
+    {
+      hashBucketVars = new float[nBuildInVars];
+      arrayBuildInVariablesCache[currentHashBucket] = hashBucketVars;
+    }
 
-	 // calc hash bucket from crc
+    if ( crc == _arrayCrc[currentHashBucket] )
-	 int lastHashBucket = currentHashBucket;
+    {
-     int crc  = Crc32.crcWithInverseBit(ab, inverseDirection ? inverseBitByteIndex : -1 );
+      byte[] abBucket = _arrayBitmap[currentHashBucket];
-     int hashSize = _arrayBitmap.length;
+      if ( ab == abBucket ) // fast identity check
-     currentHashBucket =  (crc & 0xfffffff) % hashSize;
+      {
-     hashBucketVars = arrayBuildInVariablesCache[currentHashBucket];
+        return;
-     currentByteArray = ab;
+      }
-     currentInverseDirection = inverseDirection;
+      requests2++;
-     byte[] abBucket = _arrayBitmap[currentHashBucket];
-     boolean inverseBucket = _arrayInverse[currentHashBucket];
-	 if ( ab == abBucket && inverseBucket == inverseDirection ) // fast identity check
-     {
-	   return lastHashBucket == currentHashBucket;
-	 }
-	 requests2++;
 
-	 // compare input value to hash bucket content
+      // compare input value to hash bucket content
-     boolean hashBucketEquals = false;
+      boolean hashBucketEquals = false;
-     if ( crc == _arrayCrc[currentHashBucket] )
+      int abLen = ab.length;
-     {
+      if ( abBucket != null && abBucket.length == abLen )
-       int abLen = ab.length;
+      {
-       if ( abBucket != null && abBucket.length == ab.length )
+        hashBucketEquals = true;
-       {
+        for ( int i = 0; i < abLen; i++ )
-    	 hashBucketEquals = true;
+        {
-    	 boolean isInverse = inverseDirection ^ inverseBucket;
+          if ( abBucket[i] != ab[i] )
-         for( int i=0; i<abLen; i++ )
+          {
-         {
+            hashBucketEquals = false;
-           byte b = ab[i];
+            break;
-           if ( isInverse && i == inverseBitByteIndex ) b ^= 1;
+          }
-    	   if ( abBucket[i] != b ) { hashBucketEquals = false; break; }
+        }
-         }
+      }
-       }
+      if ( hashBucketEquals )
-     }
+      {
-     if ( hashBucketEquals ) return lastHashBucket == currentHashBucket;
+        return;
-     cachemisses++;
+      }
-     
+    }
-     _arrayBitmap[currentHashBucket] = currentByteArray;
+    cachemisses++;
-     _arrayInverse[currentHashBucket] = currentInverseDirection;
-     _arrayCrc[currentHashBucket] = crc;
 
-     decode( lookupData, currentInverseDirection, currentByteArray );
+    _arrayBitmap[currentHashBucket] = ab;
-     evaluate( lookupData );
+    _arrayCrc[currentHashBucket] = crc;
 
-     for( int vi=0; vi<buildInVariableIdx.length; vi++ )
+    decode( lookupData, inverseDirection, ab );
-     {
+    evaluate( lookupData );
-       int idx = buildInVariableIdx[vi];
-       hashBucketVars[vi] = idx == -1 ? 0.f : variableData[idx];
-     }
 
-     return false;
+    for ( int vi = 0; vi < nBuildInVars; vi++ )
+    {
+      int idx = buildInVariableIdx[vi];
+      hashBucketVars[vi] = idx == -1 ? 0.f : variableData[idx];
+    }
   }
 
   public void dumpStatistics()

brouter-expressions/src/test/java/btools/expressions/EncodeDecodeTest.java

@@ -39,7 +39,7 @@ public class EncodeDecodeTest
     byte[] description = expctxWay.encode(lookupData);
 
     // calculate the cost factor from that description
-    expctxWay.evaluate( false, description );
+    expctxWay.evaluate( true, description ); // true = "reversedirection=yes"  (not encoded in description anymore)
 
     float costfactor = expctxWay.getCostfactor();
     Assert.assertTrue( "costfactor mismatch", Math.abs( costfactor - 5.15 ) < 0.00001 );

brouter-mapaccess/src/main/java/btools/mapaccess/DistanceChecker.java

@@ -1,16 +0,0 @@
-/**
- * Container for routig configs
- *
- * @author ab
- */
-package btools.mapaccess;
-
-public interface DistanceChecker
-{
-  /**
-   * Checks whether the given path is within a maximum distance
-   * known to the distance checker
-   * @return true if close enough
-   */
-  boolean isWithinRadius( int ilon0, int ilat0, OsmTransferNode firstTransfer, int ilon1, int ilat1 );
-}

brouter-mapaccess/src/main/java/btools/mapaccess/NodesCache.java

@@ -42,6 +42,11 @@ public final class NodesCache
 
   private long cacheSum = 0;
   private boolean garbageCollectionEnabled = false;
+  
+  public String formatStatus()
+  {
+    return "collecting=" + garbageCollectionEnabled + " cacheSum=" + cacheSum;
+  }
 
   public NodesCache( String segmentDir, OsmNodesMap nodesMap, BExpressionContextWay ctxWay, boolean carMode, boolean forceSecondaryData,
       NodesCache oldCache )
@@ -91,7 +96,7 @@ public final class NodesCache
   // clean all ghosts and enable garbage collection
   private void checkEnableCacheCleaning()
   {
-    if ( cacheSum < 500000 || garbageCollectionEnabled )
+    if ( cacheSum < 3000000 || garbageCollectionEnabled )
       return;
 
     for ( int i = 0; i < fileRows.length; i++ )

brouter-mapaccess/src/main/java/btools/mapaccess/OsmNode.java

@@ -178,8 +178,7 @@ public class OsmNode implements OsmPos
       OsmLink link = getCompatibleLink( linklon, linklat, isReverse, 2 );
       if ( link == null ) // .. not found, then check the hollow nodes
       {
-        long targetNodeId = ( (long) linklon ) << 32 | linklat;
+        OsmNode tn = hollowNodes.get( linklon, linklat ); // target node
-        OsmNode tn = hollowNodes.get( targetNodeId ); // target node
         if ( tn == null ) // node not yet known, create a new hollow proxy
         {
           tn = new OsmNode( linklon, linklat );

brouter-mapaccess/src/main/java/btools/mapaccess/OsmNodesMap.java

@@ -26,10 +26,10 @@ public final class OsmNodesMap
    * Get a node from the map
    * @return the node for the given id if exist, else null
    */
-  public OsmNode get( long id )
+  public OsmNode get( int ilon, int ilat )
   {
-    testKey.ilon = (int)(id >> 32);
+    testKey.ilon = ilon;
-    testKey.ilat = (int)(id & 0xffffffff);
+    testKey.ilat = ilat;
     return hmap.get( testKey );
   }
 
@@ -48,13 +48,4 @@ public final class OsmNodesMap
     return hmap.put( node, node );
   }
 
-
-  /**
-   * @return the number of nodes in that map
-   */
-  public int size()
-  {
-    return hmap.size();
-  }
-
 }

brouter-mem-router/src/main/java/btools/memrouter/TwinRoutingEngine.java

@@ -69,7 +69,7 @@ public class TwinRoutingEngine extends RoutingEngine
         System.out.println( "linksProcessed=" + router.linksProcessed + " linksReProcessed=" +  router.linksReProcessed);
         System.out.println( "skippedChained=" + router.skippedChained + " closedSkippedChained=" +  router.closedSkippedChained);
         
-	    System.out.println( "expCtxWay: requests: " + routingContext.expctxWay.requests + " requests2: " + routingContext.expctxWay.requests2 + " cache-misses: " + routingContext.expctxWay.cachemisses );
+	    System.out.println( "expCtxWay: requests: " + routingContext.expctxWay.cacheStats() );
         
 	  }
     }

brouter-util/src/main/java/btools/util/BitCoderContext.java

@@ -4,13 +4,16 @@ package btools.util;
 public class BitCoderContext
 {
   private byte[] ab;
+  private int idxMax;
   private int idx = -1;
-  private int bm = 0x100; // byte mask
+  private int bm = 0x100; // byte mask (write mode)
+  private int bits; // bits left in buffer (read mode)
   private int b;
 
   public BitCoderContext( byte[] ab )
   {
     this.ab = ab;
+    idxMax = ab.length-1;
   }
 
   /**
@@ -39,18 +42,32 @@ public class BitCoderContext
   /**
    * @see #encodeVarBits
    */
-  public final int decodeVarBits()
+  public final int decodeVarBits2()
   {
     int range = 0;
-    int value = 0;
     while (!decodeBit())
     {
-      value += range + 1;
       range = 2 * range + 1;
     }
-    return value + decodeBounded( range );
+    return range + decodeBounded( range );
   }
 
+  public final int decodeVarBits()
+  {
+    int range = 1;
+    int cnt = 1;
+    fillBuffer();
+    while ((b & range) == 0)
+    {
+      range = (range << 1) | 1;
+      cnt++;
+    }
+    b >>>= cnt;
+    bits -= cnt;
+    return (range >>> 1) + ( cnt > 1 ? decodeBits( cnt-1 ) : 0 );
+  }
+
+
   public final void encodeBit( boolean value )
   {
     if ( bm == 0x100 )
@@ -65,13 +82,14 @@ public class BitCoderContext
 
   public final boolean decodeBit()
   {
-    if ( bm == 0x100 )
+    if ( bits == 0 )
     {
-      bm = 1;
+      bits = 8;
-      b = ab[++idx];
+      b = ab[++idx] & 0xff;
     }
-    boolean value = ( ( b & bm ) != 0 );
+    boolean value = ( ( b & 1 ) != 0 );
-    bm <<= 1;
+    b >>>= 1;
+    bits--;
     return value;
   }
 
@@ -111,19 +129,46 @@ public class BitCoderContext
     int im = 1; // integer mask
     while (( value | im ) <= max)
     {
-      if ( bm == 0x100 )
+      if ( bits == 0 )
       {
-        bm = 1;
+        bits = 8;
-        b = ab[++idx];
+        b = ab[++idx] & 0xff;
       }
-      if ( ( b & bm ) != 0 )
+      if ( ( b & 1 ) != 0 )
         value |= im;
-      bm <<= 1;
+      b >>>= 1;
+      bits--;
       im <<= 1;
     }
     return value;
   }
 
+  public final int decodeBits( int count )
+  {
+    if ( count == 0 )
+    {
+      return 0;
+    }
+    fillBuffer();
+    int mask = 0xffffffff >>> ( 32 - count );
+    int value = b & mask;
+    b >>>= count;
+    bits -= count;
+    return value;
+  }
+  
+  private void fillBuffer()
+  {
+    while (bits < 24)
+    {
+      if ( idx < idxMax )
+      {
+        b |= (ab[++idx] & 0xff) << bits;
+      }
+      bits += 8;
+    }
+  }    
+
   /**
    * @return the encoded length in bytes
    */
@@ -135,7 +180,7 @@ public class BitCoderContext
   /**
    * @return the encoded length in bits
    */
-  public final long getBitPosition()
+  public final long getWritingBitPosition()
   {
     long bitpos = idx << 3;
     int m = bm;
@@ -147,4 +192,53 @@ public class BitCoderContext
     return bitpos;
   }
 
+  public final int getReadingBitPosition()
+  {
+    return (idx << 3) + 8 - bits;
+  }
+
+  public final void setReadingBitPosition(int pos)
+  {
+    idx = pos >>> 3;
+    bits = (idx << 3) + 8 - pos;
+    b = ab[idx] & 0xff;
+    b >>>= (8-bits);
+  }
+
+  public final void copyBitsTo( byte[] dst, int bitcount )
+  {
+    int dstIdx = 0;
+    for(;;)
+    {
+      if ( bitcount > 8 )
+      {
+        if ( bits < 8 )
+        {
+          b |= (ab[++idx] & 0xff) << bits;
+        }
+        else
+        {
+          bits -= 8;
+        }
+        dst[dstIdx++] = (byte)b;
+        b >>>= 8;
+        bitcount -= 8;
+      }
+      else
+      {
+        if ( bits < bitcount )
+        {
+          b |= (ab[++idx] & 0xff) << bits;
+          bits += 8;
+        }
+
+        int mask = 0xff >>> ( 8 - bitcount );
+        dst[dstIdx] = (byte)(b & mask);
+        bits -= bitcount;
+        b >>>= bitcount;
+        break;
+      }
+    }
+  }
+
 }

brouter-util/src/main/java/btools/util/Crc32.java

@@ -30,17 +30,15 @@ public class Crc32
     return crc;
   }
 
-  public static int crcWithInverseBit( byte[] ab, int inverseBitByteIndex )
+  public static int crcWithInverseBit( byte[] ab, boolean isInverse )
   {
-    int crc  = 0xFFFFFFFF;
+    int crc  = 0xFFFFFF ^ ( isInverse ? 0x990951ba : 0x706af48f ); // inverse is webbed into crc...
     int end = ab.length;
     for( int j=0; j<end; j++ )
     {
-      byte b = ab[j];
+      crc = (crc >>> 8) ^ crctable[(crc ^ ab[j]) & 0xff];
-      if ( j == inverseBitByteIndex ) b ^= 1;
-      crc = (crc >>> 8) ^ crctable[(crc ^ b) & 0xff];
     }
-    return crc;
+    return isInverse ? crc | 0x80000000 : crc & 0x7fffffff; // ... and set as high bit
   }
 
   private static int[] crctable = {

brouter-util/src/test/java/btools/util/BitCoderContextTest.java

@@ -19,7 +19,7 @@ public class BitCoderContextTest
     for ( int i = 0; i < 1000; i++ )
     {
       int value = ctx.decodeVarBits();
-      Assert.assertTrue( "distance value mismatch", value == i );
+      Assert.assertTrue( "distance value mismatch i=" + i + "v=" + value, value == i );
     }
   }