Index: org/apache/lucene/search/spans/SpanScorer.java
===================================================================
--- org/apache/lucene/search/spans/SpanScorer.java	(revision 393589)
+++ org/apache/lucene/search/spans/SpanScorer.java	(working copy)
@@ -18,6 +18,7 @@
 
 import java.io.IOException;
 
+import org.apache.lucene.index.NormFactors;
 import org.apache.lucene.search.Weight;
 import org.apache.lucene.search.Scorer;
 import org.apache.lucene.search.Explanation;
@@ -27,7 +28,7 @@
 class SpanScorer extends Scorer {
   private Spans spans;
   private Weight weight;
-  private byte[] norms;
+  private NormFactors normFactors;
   private float value;
 
   private boolean firstTime = true;
@@ -36,11 +37,11 @@
   private int doc;
   private float freq;
 
-  SpanScorer(Spans spans, Weight weight, Similarity similarity, byte[] norms)
+  SpanScorer(Spans spans, Weight weight, Similarity similarity, NormFactors normFactors)
     throws IOException {
     super(similarity);
     this.spans = spans;
-    this.norms = norms;
+    this.normFactors = normFactors;
     this.weight = weight;
     this.value = weight.getValue();
     doc = -1;
@@ -86,7 +87,7 @@
 
   public float score() throws IOException {
     float raw = getSimilarity().tf(freq) * value; // raw score
-    return raw * Similarity.decodeNorm(norms[doc]); // normalize
+    return raw * normFactors.getFactor(doc); // normalize
   }
 
   public Explanation explain(final int doc) throws IOException {
Index: org/apache/lucene/search/spans/SpanWeight.java
===================================================================
--- org/apache/lucene/search/spans/SpanWeight.java	(revision 393589)
+++ org/apache/lucene/search/spans/SpanWeight.java	(working copy)
@@ -23,6 +23,7 @@
 import java.util.Set;
 
 import org.apache.lucene.index.IndexReader;
+import org.apache.lucene.index.NormFactors;
 import org.apache.lucene.index.Term;
 
 import org.apache.lucene.search.Query;
@@ -69,7 +70,7 @@
   public Scorer scorer(IndexReader reader) throws IOException {
     return new SpanScorer(query.getSpans(reader), this,
                           similarity,
-                          reader.norms(query.getField()));
+                          reader.getNormFactors(query.getField()));
   }
 
   public Explanation explain(IndexReader reader, int doc)
@@ -123,9 +124,9 @@
     fieldExpl.addDetail(idfExpl);
 
     Explanation fieldNormExpl = new Explanation();
-    byte[] fieldNorms = reader.norms(field);
+    NormFactors fieldNorms = reader.getNormFactors(field);
     float fieldNorm =
-      fieldNorms!=null ? Similarity.decodeNorm(fieldNorms[doc]) : 0.0f;
+      fieldNorms!=null ? fieldNorms.getFactor(doc) : 0.0f;
     fieldNormExpl.setValue(fieldNorm);
     fieldNormExpl.setDescription("fieldNorm(field="+field+", doc="+doc+")");
     fieldExpl.addDetail(fieldNormExpl);
Index: org/apache/lucene/search/SloppyPhraseScorer.java
===================================================================
--- org/apache/lucene/search/SloppyPhraseScorer.java	(revision 393589)
+++ org/apache/lucene/search/SloppyPhraseScorer.java	(working copy)
@@ -16,14 +16,22 @@
  * limitations under the License.
  */
 
-import org.apache.lucene.index.TermPositions;
-
 import java.io.IOException;
 
+import org.apache.lucene.index.NormFactors;
+import org.apache.lucene.index.TermPositions;
+
 final class SloppyPhraseScorer extends PhraseScorer {
     private int slop;
 
     SloppyPhraseScorer(Weight weight, TermPositions[] tps, int[] positions, Similarity similarity,
+            int slop, NormFactors normFactors) {
+    super(weight, tps, positions, similarity, normFactors);
+    this.slop = slop;
+    }
+
+    /** @deprecated */
+    SloppyPhraseScorer(Weight weight, TermPositions[] tps, int[] positions, Similarity similarity,
                        int slop, byte[] norms) {
         super(weight, tps, positions, similarity, norms);
         this.slop = slop;
Index: org/apache/lucene/search/MultiPhraseQuery.java
===================================================================
--- org/apache/lucene/search/MultiPhraseQuery.java	(revision 393589)
+++ org/apache/lucene/search/MultiPhraseQuery.java	(working copy)
@@ -21,6 +21,7 @@
 
 import org.apache.lucene.index.IndexReader;
 import org.apache.lucene.index.MultipleTermPositions;
+import org.apache.lucene.index.NormFactors;
 import org.apache.lucene.index.Term;
 import org.apache.lucene.index.TermPositions;
 import org.apache.lucene.search.Query;
@@ -181,10 +182,10 @@
 
       if (slop == 0)
         return new ExactPhraseScorer(this, tps, getPositions(), similarity,
-                                     reader.norms(field));
+                                     reader.getNormFactors(field));
       else
         return new SloppyPhraseScorer(this, tps, getPositions(), similarity,
-                                      slop, reader.norms(field));
+                                      slop, reader.getNormFactors(field));
     }
 
     public Explanation explain(IndexReader reader, int doc)
@@ -223,9 +224,9 @@
       fieldExpl.addDetail(idfExpl);
 
       Explanation fieldNormExpl = new Explanation();
-      byte[] fieldNorms = reader.norms(field);
+      NormFactors fieldNorms = reader.getNormFactors(field);
       float fieldNorm =
-        fieldNorms!=null ? Similarity.decodeNorm(fieldNorms[doc]) : 0.0f;
+        fieldNorms!=null ? fieldNorms.getFactor(doc) : 0.0f;
       fieldNormExpl.setValue(fieldNorm);
       fieldNormExpl.setDescription("fieldNorm(field="+field+", doc="+doc+")");
       fieldExpl.addDetail(fieldNormExpl);
Index: org/apache/lucene/search/PhraseScorer.java
===================================================================
--- org/apache/lucene/search/PhraseScorer.java	(revision 393589)
+++ org/apache/lucene/search/PhraseScorer.java	(working copy)
@@ -22,7 +22,10 @@
 
 abstract class PhraseScorer extends Scorer {
   private Weight weight;
+
+  /** @deprecated */
   protected byte[] norms;
+  private NormFactors normFactors;
   protected float value;
 
   private boolean firstTime = true;
@@ -34,8 +37,20 @@
 
 
   PhraseScorer(Weight weight, TermPositions[] tps, int[] positions, Similarity similarity,
+          NormFactors normFactors) {
+      this(weight, tps, positions, similarity, normFactors, null);
+  }
+
+  /** @deprecated */
+  PhraseScorer(Weight weight, TermPositions[] tps, int[] positions, Similarity similarity,
                byte[] norms) {
+      this(weight, tps, positions, similarity, NormFactors.newInstance(norms), norms);
+  }
+
+  private PhraseScorer(Weight weight, TermPositions[] tps, int[] positions, Similarity similarity,
+               NormFactors normFactors, byte[] norms) {
     super(similarity);
+    this.normFactors = normFactors;
     this.norms = norms;
     this.weight = weight;
     this.value = weight.getValue();
@@ -89,7 +104,7 @@
   public float score() throws IOException {
     //System.out.println("scoring " + first.doc);
     float raw = getSimilarity().tf(freq) * value; // raw score
-    return raw * Similarity.decodeNorm(norms[first.doc]); // normalize
+    return raw * getNormFactors().getFactor(first.doc); // normalize
   }
 
   public boolean skipTo(int target) throws IOException {
@@ -149,6 +164,13 @@
     return tfExplanation;
   }
 
+  /**
+   * @return the NormFactors for the field associated with this phrase.
+   */
+  public NormFactors getNormFactors() {
+      return this.normFactors;
+  }
+
   public String toString() { return "scorer(" + weight + ")"; }
 
 }
Index: org/apache/lucene/search/PhraseQuery.java
===================================================================
--- org/apache/lucene/search/PhraseQuery.java	(revision 393589)
+++ org/apache/lucene/search/PhraseQuery.java	(working copy)
@@ -20,6 +20,7 @@
 import java.util.Set;
 import java.util.Vector;
 
+import org.apache.lucene.index.NormFactors;
 import org.apache.lucene.index.Term;
 import org.apache.lucene.index.TermPositions;
 import org.apache.lucene.index.IndexReader;
@@ -147,11 +148,11 @@
 
       if (slop == 0)				  // optimize exact case
         return new ExactPhraseScorer(this, tps, getPositions(), similarity,
-                                     reader.norms(field));
+                                     reader.getNormFactors(field));
       else
         return
           new SloppyPhraseScorer(this, tps, getPositions(), similarity, slop,
-                                 reader.norms(field));
+                                 reader.getNormFactors(field));
 
     }
 
@@ -211,9 +212,9 @@
       fieldExpl.addDetail(idfExpl);
 
       Explanation fieldNormExpl = new Explanation();
-      byte[] fieldNorms = reader.norms(field);
+      NormFactors fieldNorms = reader.getNormFactors(field);
       float fieldNorm =
-        fieldNorms!=null ? Similarity.decodeNorm(fieldNorms[doc]) : 0.0f;
+        fieldNorms!=null ? fieldNorms.getFactor(doc) : 0.0f;
       fieldNormExpl.setValue(fieldNorm);
       fieldNormExpl.setDescription("fieldNorm(field="+field+", doc="+doc+")");
       fieldExpl.addDetail(fieldNormExpl);
Index: org/apache/lucene/search/TermQuery.java
===================================================================
--- org/apache/lucene/search/TermQuery.java	(revision 393589)
+++ org/apache/lucene/search/TermQuery.java	(working copy)
@@ -19,6 +19,7 @@
 import java.io.IOException;
 import java.util.Set;
 
+import org.apache.lucene.index.NormFactors;
 import org.apache.lucene.index.Term;
 import org.apache.lucene.index.TermDocs;
 import org.apache.lucene.index.IndexReader;
@@ -66,7 +67,7 @@
         return null;
 
       return new TermScorer(this, termDocs, similarity,
-                            reader.norms(term.field()));
+                            reader.getNormFactors(term.field()));
     }
 
     public Explanation explain(IndexReader reader, int doc)
@@ -107,9 +108,9 @@
       fieldExpl.addDetail(idfExpl);
 
       Explanation fieldNormExpl = new Explanation();
-      byte[] fieldNorms = reader.norms(field);
+      NormFactors fieldNorms = reader.getNormFactors(field);
       float fieldNorm =
-        fieldNorms!=null ? Similarity.decodeNorm(fieldNorms[doc]) : 0.0f;
+        fieldNorms!=null ? fieldNorms.getFactor(doc) : 0.0f;
       fieldNormExpl.setValue(fieldNorm);
       fieldNormExpl.setDescription("fieldNorm(field="+field+", doc="+doc+")");
       fieldExpl.addDetail(fieldNormExpl);
Index: org/apache/lucene/search/ExactPhraseScorer.java
===================================================================
--- org/apache/lucene/search/ExactPhraseScorer.java	(revision 393589)
+++ org/apache/lucene/search/ExactPhraseScorer.java	(working copy)
@@ -22,6 +22,12 @@
 final class ExactPhraseScorer extends PhraseScorer {
 
   ExactPhraseScorer(Weight weight, TermPositions[] tps, int[] positions, Similarity similarity,
+            NormFactors normFactors) {
+    super(weight, tps, positions, similarity, normFactors);
+    }
+
+  /** @deprecated */
+    ExactPhraseScorer(Weight weight, TermPositions[] tps, int[] positions, Similarity similarity,
                     byte[] norms) {
     super(weight, tps, positions, similarity, norms);
   }
Index: org/apache/lucene/search/TermScorer.java
===================================================================
--- org/apache/lucene/search/TermScorer.java	(revision 393589)
+++ org/apache/lucene/search/TermScorer.java	(working copy)
@@ -18,6 +18,7 @@
 
 import java.io.IOException;
 
+import org.apache.lucene.index.NormFactors;
 import org.apache.lucene.index.TermDocs;
 
 /** Expert: A <code>Scorer</code> for documents matching a <code>Term</code>.
@@ -25,7 +26,7 @@
 final class TermScorer extends Scorer {
   private Weight weight;
   private TermDocs termDocs;
-  private byte[] norms;
+  private NormFactors normFactors;
   private float weightValue;
   private int doc;
 
@@ -44,17 +45,30 @@
    * @param norms The field norms of the document fields for the <code>Term</code>.
    */
   TermScorer(Weight weight, TermDocs td, Similarity similarity,
-             byte[] norms) {
+             NormFactors normFactors) {
     super(similarity);
     this.weight = weight;
     this.termDocs = td;
-    this.norms = norms;
+    this.normFactors = normFactors;
     this.weightValue = weight.getValue();
 
     for (int i = 0; i < SCORE_CACHE_SIZE; i++)
       scoreCache[i] = getSimilarity().tf(i) * weightValue;
   }
 
+  /** Construct a <code>TermScorer</code>.
+   * @param weight The weight of the <code>Term</code> in the query.
+   * @param td An iterator over the documents matching the <code>Term</code>.
+   * @param similarity The </code>Similarity</code> implementation to be used for score computations.
+   * @param norms The field norms of the document fields for the <code>Term</code>.
+   * @deprecated
+   */
+  TermScorer(Weight weight, TermDocs td, Similarity similarity,
+             byte[] norms) {
+      this(weight, td, similarity, NormFactors.newInstance(norms));
+  }
+
+
   public void score(HitCollector hc) throws IOException {
     next();
     score(hc, Integer.MAX_VALUE);
@@ -62,7 +76,6 @@
 
   protected boolean score(HitCollector c, int end) throws IOException {
     Similarity similarity = getSimilarity();      // cache sim in local
-    float[] normDecoder = Similarity.getNormDecoder();
     while (doc < end) {                           // for docs in window
       int f = freqs[pointer];
       float score =                               // compute tf(f)*weight
@@ -70,7 +83,7 @@
          ? scoreCache[f]                          // cache hit
          : similarity.tf(f)*weightValue;          // cache miss
 
-      score *= normDecoder[norms[doc] & 0xFF];    // normalize for field
+      score *= normFactors.getFactor(doc);    // normalize for field
 
       c.collect(doc, score);                      // collect score
 
@@ -115,14 +128,14 @@
     return true;
   }
 
-  public float score() {
+  public float score() throws IOException {
     int f = freqs[pointer];
     float raw =                                   // compute tf(f)*weight
       f < SCORE_CACHE_SIZE                        // check cache
       ? scoreCache[f]                             // cache hit
       : getSimilarity().tf(f)*weightValue;        // cache miss
 
-    return raw * Similarity.decodeNorm(norms[doc]); // normalize for field
+    return raw * normFactors.getFactor(doc); // normalize for field
   }
 
   /** Skips to the first match beyond the current whose document number is
Index: org/apache/lucene/index/MultiReader.java
===================================================================
--- org/apache/lucene/index/MultiReader.java	(revision 393589)
+++ org/apache/lucene/index/MultiReader.java	(working copy)
@@ -30,6 +30,7 @@
 public class MultiReader extends IndexReader {
   private IndexReader[] subReaders;
   private int[] starts;                           // 1st docno for each segment
+  private Hashtable normFactorsCache = new Hashtable();
   private Hashtable normsCache = new Hashtable();
   private int maxDoc = 0;
   private int numDocs = -1;
@@ -159,6 +160,18 @@
     return ones;
   }
 
+  public synchronized NormFactors getNormFactors(String field) throws IOException {
+      NormFactors factors = (NormFactors) normFactorsCache.get(field);
+      if (factors != null)
+          return factors;
+      if (!hasNorms(field))
+          return NormFactors.getEmptyInstance();
+
+      NormFactors multiNorms = new MultiNormFactors(field);
+      normFactorsCache.put(field, multiNorms);
+      return multiNorms;
+  }
+
   public synchronized byte[] norms(String field) throws IOException {
     byte[] bytes = (byte[])normsCache.get(field);
     if (bytes != null)
@@ -187,6 +200,7 @@
   protected void doSetNorm(int n, String field, byte value)
     throws IOException {
     normsCache.remove(field);                         // clear cache
+    normFactorsCache.remove(field);
     int i = readerIndex(n);                           // find segment num
     subReaders[i].setNorm(n-starts[i], field, value); // dispatch
   }
@@ -237,6 +251,23 @@
     }
     return fieldSet;
   }
+
+  /**
+   * Represents a set of norm factors that spans a set of documents.
+   */
+  class MultiNormFactors extends NormFactors {
+      private String field;
+
+      public MultiNormFactors(String field) throws IOException {
+          this.field = field;
+      }
+
+      public byte getByte(int doc) throws IOException {
+          int subReader = MultiReader.this.readerIndex(doc);
+          NormFactors subNormFactors = subReaders[subReader].getNormFactors(this.field);
+          return subNormFactors.getByte(doc - MultiReader.this.starts[subReader]);
+      }
+  }
 }
 
 class MultiTermEnum extends TermEnum {
Index: org/apache/lucene/index/IndexReader.java
===================================================================
--- org/apache/lucene/index/IndexReader.java	(revision 393589)
+++ org/apache/lucene/index/IndexReader.java	(working copy)
@@ -367,13 +367,27 @@
   public boolean hasNorms(String field) throws IOException {
     // backward compatible implementation.
     // SegmentReader has an efficient implementation.
-    return norms(field) != null;
+    return getNormFactors(field) != null;
   }
 
+  /**
+   * Returns the normalization factors for the name field of every document.
+   * This is used by the search code to score documents.
+   *
+   * @see Field#setBoost(float)
+   */
+  public NormFactors getNormFactors(String field) throws IOException {
+      // This implementation should eventually go away when {@link #norms(String)}
+      // goes away
+      return NormFactors.newInstance(norms(field));
+  }
+
+
   /** Returns the byte-encoded normalization factor for the named field of
    * every document.  This is used by the search code to score documents.
    *
    * @see Field#setBoost(float)
+   * @deprecated use {@link #getNorms(String)} instead.
    */
   public abstract byte[] norms(String field) throws IOException;
 
Index: org/apache/lucene/index/FilterIndexReader.java
===================================================================
--- org/apache/lucene/index/FilterIndexReader.java	(revision 393589)
+++ org/apache/lucene/index/FilterIndexReader.java	(working copy)
@@ -110,6 +110,8 @@
     return in.hasNorms(field);
   }
 
+  public NormFactors getNormFactors(String f) throws IOException { return in.getNormFactors(f); }
+  /** @deprecated */
   public byte[] norms(String f) throws IOException { return in.norms(f); }
   public void norms(String f, byte[] bytes, int offset) throws IOException {
     in.norms(f, bytes, offset);
Index: org/apache/lucene/index/ParallelReader.java
===================================================================
--- org/apache/lucene/index/ParallelReader.java	(revision 393589)
+++ org/apache/lucene/index/ParallelReader.java	(working copy)
@@ -169,6 +169,13 @@
     return ((IndexReader)fieldToReader.get(field)).hasNorms(field);
   }
 
+  public NormFactors getNormFactors(String field) throws IOException {
+      return ((IndexReader)fieldToReader.get(field)).getNormFactors(field);
+  }
+
+  /**
+   * @deprecated
+   */
   public byte[] norms(String field) throws IOException {
     return ((IndexReader)fieldToReader.get(field)).norms(field);
   }
Index: org/apache/lucene/index/SegmentReader.java
===================================================================
--- org/apache/lucene/index/SegmentReader.java	(revision 393589)
+++ org/apache/lucene/index/SegmentReader.java	(working copy)
@@ -51,7 +51,7 @@
   // Compound File Reader when based on a compound file segment
   CompoundFileReader cfsReader = null;
 
-  private class Norm {
+  private class Norm extends NormFactors {
     public Norm(IndexInput in, int number)
     {
       this.in = in;
@@ -81,6 +81,10 @@
       directory().renameFile(segment + ".tmp", fileName);
       this.dirty = false;
     }
+
+    public byte getByte(int doc) {
+        return bytes[doc];
+    }
   }
 
   private Hashtable norms = new Hashtable();
@@ -375,7 +379,11 @@
     return ones;
   }
 
+
   // can return null if norms aren't stored
+  /**
+   * @deprecated
+   */
   protected synchronized byte[] getNorms(String field) throws IOException {
     Norm norm = (Norm) norms.get(field);
     if (norm == null) return null;  // not indexed, or norms not stored
@@ -388,6 +396,18 @@
     return norm.bytes;
   }
 
+  public synchronized NormFactors getNormFactors(String field) throws IOException {
+      Norm norm = (Norm) norms.get(field);
+      if (norm == null) return NormFactors.getEmptyInstance();  // not indexed, or norms not stored
+
+      if (norm.bytes == null) {                     // value not yet read
+        byte[] bytes = new byte[maxDoc()];
+        norms(field, bytes, 0);
+        norm.bytes = bytes;                         // cache it
+      }
+      return norm;
+  }
+
   // returns fake norms if norms aren't available
   public synchronized byte[] norms(String field) throws IOException {
     byte[] bytes = getNorms(field);