LUCENE-4184: Performance improvements to Packed64SingleBlock.

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1356640 13f79535-47bb-0310-9956-ffa450edef68

lucene/CHANGES.txt

@@ -31,6 +31,9 @@ Optimizations
 * LUCENE-4171: Performance improvements to Packed64.
   (Toke Eskildsen via Adrien Grand)
 
+* LUCENE-4184: Performance improvements to the aligned packed bits impl.
+  (Toke Eskildsen, Adrien Grand)
+
 Bug Fixes
 
 * LUCENE-4176: Fix AnalyzingQueryParser to analyze range endpoints as bytes,

lucene/core/src/java/org/apache/lucene/util/packed/Packed64SingleBlock.java

@@ -1,3 +1,5 @@
+// This file has been automatically generated, DO NOT EDIT
+
 package org.apache.lucene.util.packed;
 
 /*
@@ -28,47 +30,10 @@ import org.apache.lucene.util.RamUsageEstimator;
  * speed by ensuring that a single block needs to be read/written in order to
  * read/write a value.
  */
-final class Packed64SingleBlock extends PackedInts.MutableImpl {
+abstract class Packed64SingleBlock extends PackedInts.MutableImpl {
 
-  private static final int[] SUPPORTED_BITS_PER_VALUE = new int[] {1, 2, 3, 4,
+  public static final int MAX_SUPPORTED_BITS_PER_VALUE = 32;
-      5, 6, 7, 8, 9, 10, 12, 16, 21, 32};
+  private static final int[] SUPPORTED_BITS_PER_VALUE = new int[] {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 16, 21, 32};
-  static final int MAX_SUPPORTED_BITS_PER_VALUE = 32;
-  private static final long[][] WRITE_MASKS = new long[MAX_SUPPORTED_BITS_PER_VALUE+1][];
-  private static final int[][] SHIFTS = new int[MAX_SUPPORTED_BITS_PER_VALUE+1][];
-  static {
-    for (int bpv : SUPPORTED_BITS_PER_VALUE) {
-      initMasks(bpv);
-    }
-  }
-
-  protected static void initMasks(int bpv) {
-    int valuesPerBlock = Long.SIZE / bpv;
-    long[] writeMasks = new long[valuesPerBlock];
-    int[] shifts = new int[valuesPerBlock];
-    long bits = (1L << bpv) - 1;
-    for (int i = 0; i < valuesPerBlock; ++i) {
-      shifts[i] = bpv * i;
-      writeMasks[i] = ~(bits << shifts[i]);
-    }
-    WRITE_MASKS[bpv] = writeMasks;
-    SHIFTS[bpv] = shifts;
-  }
-
-  public static Packed64SingleBlock create(int valueCount, int bitsPerValue) {
-    if (isSupported(bitsPerValue)) {
-      return new Packed64SingleBlock(valueCount, bitsPerValue);
-    }
-    throw new IllegalArgumentException("Unsupported bitsPerValue: " + bitsPerValue);
-  }
-
-  public static Packed64SingleBlock create(DataInput in,
-      int valueCount, int bitsPerValue) throws IOException {
-    Packed64SingleBlock reader = create(valueCount, bitsPerValue);
-    for (int i = 0; i < reader.blocks.length; ++i) {
-      reader.blocks[i] = in.readLong();
-    }
-    return reader;
-  }
 
   public static boolean isSupported(int bitsPerValue) {
     return Arrays.binarySearch(SUPPORTED_BITS_PER_VALUE, bitsPerValue) >= 0;
@@ -80,41 +45,27 @@ final class Packed64SingleBlock extends PackedInts.MutableImpl {
     return (float) overhead / valuesPerBlock;
   }
 
-  final long[] blocks;
-  final int valuesPerBlock;
-  final int[] shifts;
-  final long[] writeMasks;
-  final long readMask;
-
-  Packed64SingleBlock(int valueCount, int bitsPerValue) {
-    super(valueCount, bitsPerValue);
-    assert isSupported(bitsPerValue);
-    valuesPerBlock = Long.SIZE / bitsPerValue;
-    blocks = new long[requiredCapacity(valueCount, valuesPerBlock)];
-    shifts = SHIFTS[bitsPerValue];
-    writeMasks = WRITE_MASKS[bitsPerValue];
-    readMask = ~writeMasks[0];
-  }
-
   private static int requiredCapacity(int valueCount, int valuesPerBlock) {
     return valueCount / valuesPerBlock
         + (valueCount % valuesPerBlock == 0 ? 0 : 1);
   }
 
-  private int blockOffset(int offset) {
+  final long[] blocks;
-    return offset / valuesPerBlock;
-  }
 
-  private int offsetInBlock(int offset) {
+  Packed64SingleBlock(int valueCount, int bitsPerValue) {
-    return offset % valuesPerBlock;
+    super(valueCount, bitsPerValue);
+    assert isSupported(bitsPerValue);
+    final int valuesPerBlock = 64 / bitsPerValue;
+    blocks = new long[requiredCapacity(valueCount, valuesPerBlock)];
   }
 
   @Override
-  public long get(int index) {
+  public void clear() {
-    final int o = blockOffset(index);
+    Arrays.fill(blocks, 0L);
-    final int b = offsetInBlock(index);
+  }
 
-    return (blocks[o] >>> shifts[b]) & readMask;
+  public long ramBytesUsed() {
+    return RamUsageEstimator.sizeOf(blocks);
   }
 
   @Override
@@ -127,7 +78,8 @@ final class Packed64SingleBlock extends PackedInts.MutableImpl {
     final int originalIndex = index;
 
     // go to the next block boundary
-    final int offsetInBlock = offsetInBlock(index);
+    final int valuesPerBlock = 64 / bitsPerValue;
+    final int offsetInBlock = index % valuesPerBlock;
     if (offsetInBlock != 0) {
       for (int i = offsetInBlock; i < valuesPerBlock && len > 0; ++i) {
         arr[off++] = get(index++);
@@ -139,14 +91,15 @@ final class Packed64SingleBlock extends PackedInts.MutableImpl {
     }
 
     // bulk get
-    assert offsetInBlock(index) == 0;
+    assert index % valuesPerBlock == 0;
-    final int startBlock = blockOffset(index);
+    final long readMask = (1L << bitsPerValue) - 1;
-    final int endBlock = blockOffset(index + len);
+    final int startBlock = index / valuesPerBlock;
+    final int endBlock = (index + len) / valuesPerBlock;
     final int diff = (endBlock - startBlock) * valuesPerBlock;
     index += diff; len -= diff;
     for (int block = startBlock; block < endBlock; ++block) {
       for (int i = 0; i < valuesPerBlock; ++i) {
-        arr[off++] = (blocks[block] >> shifts[i]) & readMask;
+        arr[off++] = (blocks[block] >>> (i * bitsPerValue)) & readMask;
       }
     }
 
@@ -161,14 +114,6 @@ final class Packed64SingleBlock extends PackedInts.MutableImpl {
     }
   }
 
-  @Override
-  public void set(int index, long value) {
-    final int o = blockOffset(index);
-    final int b = offsetInBlock(index);
-
-    blocks[o] = (blocks[o] & writeMasks[b]) | (value << shifts[b]);
-  }
-
   @Override
   public int set(int index, long[] arr, int off, int len) {
     assert len > 0 : "len must be > 0 (got " + len + ")";
@@ -179,7 +124,8 @@ final class Packed64SingleBlock extends PackedInts.MutableImpl {
     final int originalIndex = index;
 
     // go to the next block boundary
-    final int offsetInBlock = offsetInBlock(index);
+    final int valuesPerBlock = 64 / bitsPerValue;
+    final int offsetInBlock = index % valuesPerBlock;
     if (offsetInBlock != 0) {
       for (int i = offsetInBlock; i < valuesPerBlock && len > 0; ++i) {
         set(index++, arr[off++]);
@@ -191,15 +137,15 @@ final class Packed64SingleBlock extends PackedInts.MutableImpl {
     }
 
     // bulk set
-    assert offsetInBlock(index) == 0;
+    assert index % valuesPerBlock == 0;
-    final int startBlock = blockOffset(index);
+    final int startBlock = index / valuesPerBlock;
-    final int endBlock = blockOffset(index + len);
+    final int endBlock = (index + len) / valuesPerBlock;
     final int diff = (endBlock - startBlock) * valuesPerBlock;
     index += diff; len -= diff;
     for (int block = startBlock; block < endBlock; ++block) {
       long next = 0L;
       for (int i = 0; i < valuesPerBlock; ++i) {
-        next |= (arr[off++] << shifts[i]);
+        next |= (arr[off++] << (i * bitsPerValue));
       }
       blocks[block] = next;
     }
@@ -219,8 +165,9 @@ final class Packed64SingleBlock extends PackedInts.MutableImpl {
   public void fill(int fromIndex, int toIndex, long val) {
     assert fromIndex >= 0;
     assert fromIndex <= toIndex;
-    assert (val & readMask) == val;
+    assert PackedInts.bitsRequired(val) <= bitsPerValue;
 
+    final int valuesPerBlock = 64 / bitsPerValue;
     if (toIndex - fromIndex <= valuesPerBlock << 1) {
       // there needs to be at least one full block to set for the block
       // approach to be worth trying
@@ -229,22 +176,22 @@ final class Packed64SingleBlock extends PackedInts.MutableImpl {
     }
 
     // set values naively until the next block start
-    int fromOffsetInBlock = offsetInBlock(fromIndex);
+    int fromOffsetInBlock = fromIndex % valuesPerBlock;
     if (fromOffsetInBlock != 0) {
       for (int i = fromOffsetInBlock; i < valuesPerBlock; ++i) {
         set(fromIndex++, val);
       }
-      assert offsetInBlock(fromIndex) == 0;
+      assert fromIndex % valuesPerBlock == 0;
     }
 
     // bulk set of the inner blocks
-    final int fromBlock = blockOffset(fromIndex);
+    final int fromBlock = fromIndex / valuesPerBlock;
-    final int toBlock = blockOffset(toIndex);
+    final int toBlock = toIndex / valuesPerBlock;
     assert fromBlock * valuesPerBlock == fromIndex;
 
     long blockValue = 0L;
     for (int i = 0; i < valuesPerBlock; ++i) {
-      blockValue = blockValue | (val << shifts[i]);
+      blockValue = blockValue | (val << (i * bitsPerValue));
     }
     Arrays.fill(blocks, fromBlock, toBlock, blockValue);
 
@@ -254,15 +201,6 @@ final class Packed64SingleBlock extends PackedInts.MutableImpl {
     }
   }
 
-  @Override
-  public void clear() {
-    Arrays.fill(blocks, 0L);
-  }
-
-  public long ramBytesUsed() {
-    return RamUsageEstimator.sizeOf(blocks);
-  }
-
   @Override
   protected int getFormat() {
     return PackedInts.PACKED_SINGLE_BLOCK;
@@ -274,4 +212,384 @@ final class Packed64SingleBlock extends PackedInts.MutableImpl {
         + ", size=" + size() + ", elements.length=" + blocks.length + ")";
   }
 
+  public static Packed64SingleBlock create(DataInput in,
+      int valueCount, int bitsPerValue) throws IOException {
+    Packed64SingleBlock reader = create(valueCount, bitsPerValue);
+    for (int i = 0; i < reader.blocks.length; ++i) {
+      reader.blocks[i] = in.readLong();
+    }
+    return reader;
+  }
+
+  public static Packed64SingleBlock create(int valueCount, int bitsPerValue) {
+    switch (bitsPerValue) {
+      case 1:
+        return new Packed64SingleBlock1(valueCount);
+      case 2:
+        return new Packed64SingleBlock2(valueCount);
+      case 3:
+        return new Packed64SingleBlock3(valueCount);
+      case 4:
+        return new Packed64SingleBlock4(valueCount);
+      case 5:
+        return new Packed64SingleBlock5(valueCount);
+      case 6:
+        return new Packed64SingleBlock6(valueCount);
+      case 7:
+        return new Packed64SingleBlock7(valueCount);
+      case 8:
+        return new Packed64SingleBlock8(valueCount);
+      case 9:
+        return new Packed64SingleBlock9(valueCount);
+      case 10:
+        return new Packed64SingleBlock10(valueCount);
+      case 12:
+        return new Packed64SingleBlock12(valueCount);
+      case 16:
+        return new Packed64SingleBlock16(valueCount);
+      case 21:
+        return new Packed64SingleBlock21(valueCount);
+      case 32:
+        return new Packed64SingleBlock32(valueCount);
+      default:
+        throw new IllegalArgumentException("Unsupported number of bits per value: " + 32);
+    }
+  }
+
+  static class Packed64SingleBlock1 extends Packed64SingleBlock {
+
+    Packed64SingleBlock1(int valueCount) {
+      super(valueCount, 1);
+    }
+
+    @Override
+    public long get(int index) {
+      final int o = index >>> 6;
+      final int b = index & 63;
+      final int shift = b << 0;
+      return (blocks[o] >>> shift) & 1L;
+    }
+
+    @Override
+    public void set(int index, long value) {
+      final int o = index >>> 6;
+      final int b = index & 63;
+      final int shift = b << 0;
+      blocks[o] = (blocks[o] & ~(1L << shift)) | (value << shift);
+    }
+
+  }
+
+  static class Packed64SingleBlock2 extends Packed64SingleBlock {
+
+    Packed64SingleBlock2(int valueCount) {
+      super(valueCount, 2);
+    }
+
+    @Override
+    public long get(int index) {
+      final int o = index >>> 5;
+      final int b = index & 31;
+      final int shift = b << 1;
+      return (blocks[o] >>> shift) & 3L;
+    }
+
+    @Override
+    public void set(int index, long value) {
+      final int o = index >>> 5;
+      final int b = index & 31;
+      final int shift = b << 1;
+      blocks[o] = (blocks[o] & ~(3L << shift)) | (value << shift);
+    }
+
+  }
+
+  static class Packed64SingleBlock3 extends Packed64SingleBlock {
+
+    Packed64SingleBlock3(int valueCount) {
+      super(valueCount, 3);
+    }
+
+    @Override
+    public long get(int index) {
+      final int o = index / 21;
+      final int b = index % 21;
+      final int shift = b * 3;
+      return (blocks[o] >>> shift) & 7L;
+    }
+
+    @Override
+    public void set(int index, long value) {
+      final int o = index / 21;
+      final int b = index % 21;
+      final int shift = b * 3;
+      blocks[o] = (blocks[o] & ~(7L << shift)) | (value << shift);
+    }
+
+  }
+
+  static class Packed64SingleBlock4 extends Packed64SingleBlock {
+
+    Packed64SingleBlock4(int valueCount) {
+      super(valueCount, 4);
+    }
+
+    @Override
+    public long get(int index) {
+      final int o = index >>> 4;
+      final int b = index & 15;
+      final int shift = b << 2;
+      return (blocks[o] >>> shift) & 15L;
+    }
+
+    @Override
+    public void set(int index, long value) {
+      final int o = index >>> 4;
+      final int b = index & 15;
+      final int shift = b << 2;
+      blocks[o] = (blocks[o] & ~(15L << shift)) | (value << shift);
+    }
+
+  }
+
+  static class Packed64SingleBlock5 extends Packed64SingleBlock {
+
+    Packed64SingleBlock5(int valueCount) {
+      super(valueCount, 5);
+    }
+
+    @Override
+    public long get(int index) {
+      final int o = index / 12;
+      final int b = index % 12;
+      final int shift = b * 5;
+      return (blocks[o] >>> shift) & 31L;
+    }
+
+    @Override
+    public void set(int index, long value) {
+      final int o = index / 12;
+      final int b = index % 12;
+      final int shift = b * 5;
+      blocks[o] = (blocks[o] & ~(31L << shift)) | (value << shift);
+    }
+
+  }
+
+  static class Packed64SingleBlock6 extends Packed64SingleBlock {
+
+    Packed64SingleBlock6(int valueCount) {
+      super(valueCount, 6);
+    }
+
+    @Override
+    public long get(int index) {
+      final int o = index / 10;
+      final int b = index % 10;
+      final int shift = b * 6;
+      return (blocks[o] >>> shift) & 63L;
+    }
+
+    @Override
+    public void set(int index, long value) {
+      final int o = index / 10;
+      final int b = index % 10;
+      final int shift = b * 6;
+      blocks[o] = (blocks[o] & ~(63L << shift)) | (value << shift);
+    }
+
+  }
+
+  static class Packed64SingleBlock7 extends Packed64SingleBlock {
+
+    Packed64SingleBlock7(int valueCount) {
+      super(valueCount, 7);
+    }
+
+    @Override
+    public long get(int index) {
+      final int o = index / 9;
+      final int b = index % 9;
+      final int shift = b * 7;
+      return (blocks[o] >>> shift) & 127L;
+    }
+
+    @Override
+    public void set(int index, long value) {
+      final int o = index / 9;
+      final int b = index % 9;
+      final int shift = b * 7;
+      blocks[o] = (blocks[o] & ~(127L << shift)) | (value << shift);
+    }
+
+  }
+
+  static class Packed64SingleBlock8 extends Packed64SingleBlock {
+
+    Packed64SingleBlock8(int valueCount) {
+      super(valueCount, 8);
+    }
+
+    @Override
+    public long get(int index) {
+      final int o = index >>> 3;
+      final int b = index & 7;
+      final int shift = b << 3;
+      return (blocks[o] >>> shift) & 255L;
+    }
+
+    @Override
+    public void set(int index, long value) {
+      final int o = index >>> 3;
+      final int b = index & 7;
+      final int shift = b << 3;
+      blocks[o] = (blocks[o] & ~(255L << shift)) | (value << shift);
+    }
+
+  }
+
+  static class Packed64SingleBlock9 extends Packed64SingleBlock {
+
+    Packed64SingleBlock9(int valueCount) {
+      super(valueCount, 9);
+    }
+
+    @Override
+    public long get(int index) {
+      final int o = index / 7;
+      final int b = index % 7;
+      final int shift = b * 9;
+      return (blocks[o] >>> shift) & 511L;
+    }
+
+    @Override
+    public void set(int index, long value) {
+      final int o = index / 7;
+      final int b = index % 7;
+      final int shift = b * 9;
+      blocks[o] = (blocks[o] & ~(511L << shift)) | (value << shift);
+    }
+
+  }
+
+  static class Packed64SingleBlock10 extends Packed64SingleBlock {
+
+    Packed64SingleBlock10(int valueCount) {
+      super(valueCount, 10);
+    }
+
+    @Override
+    public long get(int index) {
+      final int o = index / 6;
+      final int b = index % 6;
+      final int shift = b * 10;
+      return (blocks[o] >>> shift) & 1023L;
+    }
+
+    @Override
+    public void set(int index, long value) {
+      final int o = index / 6;
+      final int b = index % 6;
+      final int shift = b * 10;
+      blocks[o] = (blocks[o] & ~(1023L << shift)) | (value << shift);
+    }
+
+  }
+
+  static class Packed64SingleBlock12 extends Packed64SingleBlock {
+
+    Packed64SingleBlock12(int valueCount) {
+      super(valueCount, 12);
+    }
+
+    @Override
+    public long get(int index) {
+      final int o = index / 5;
+      final int b = index % 5;
+      final int shift = b * 12;
+      return (blocks[o] >>> shift) & 4095L;
+    }
+
+    @Override
+    public void set(int index, long value) {
+      final int o = index / 5;
+      final int b = index % 5;
+      final int shift = b * 12;
+      blocks[o] = (blocks[o] & ~(4095L << shift)) | (value << shift);
+    }
+
+  }
+
+  static class Packed64SingleBlock16 extends Packed64SingleBlock {
+
+    Packed64SingleBlock16(int valueCount) {
+      super(valueCount, 16);
+    }
+
+    @Override
+    public long get(int index) {
+      final int o = index >>> 2;
+      final int b = index & 3;
+      final int shift = b << 4;
+      return (blocks[o] >>> shift) & 65535L;
+    }
+
+    @Override
+    public void set(int index, long value) {
+      final int o = index >>> 2;
+      final int b = index & 3;
+      final int shift = b << 4;
+      blocks[o] = (blocks[o] & ~(65535L << shift)) | (value << shift);
+    }
+
+  }
+
+  static class Packed64SingleBlock21 extends Packed64SingleBlock {
+
+    Packed64SingleBlock21(int valueCount) {
+      super(valueCount, 21);
+    }
+
+    @Override
+    public long get(int index) {
+      final int o = index / 3;
+      final int b = index % 3;
+      final int shift = b * 21;
+      return (blocks[o] >>> shift) & 2097151L;
+    }
+
+    @Override
+    public void set(int index, long value) {
+      final int o = index / 3;
+      final int b = index % 3;
+      final int shift = b * 21;
+      blocks[o] = (blocks[o] & ~(2097151L << shift)) | (value << shift);
+    }
+
+  }
+
+  static class Packed64SingleBlock32 extends Packed64SingleBlock {
+
+    Packed64SingleBlock32(int valueCount) {
+      super(valueCount, 32);
+    }
+
+    @Override
+    public long get(int index) {
+      final int o = index >>> 1;
+      final int b = index & 1;
+      final int shift = b << 5;
+      return (blocks[o] >>> shift) & 4294967295L;
+    }
+
+    @Override
+    public void set(int index, long value) {
+      final int o = index >>> 1;
+      final int b = index & 1;
+      final int shift = b << 5;
+      blocks[o] = (blocks[o] & ~(4294967295L << shift)) | (value << shift);
+    }
+
+  }
+
 }

lucene/core/src/java/org/apache/lucene/util/packed/gen_Packed64SingleBlock.py

@@ -0,0 +1,302 @@
+#! /usr/bin/env python
+
+# Licensed to the Apache Software Foundation (ASF) under one or more
+# contributor license agreements.  See the NOTICE file distributed with
+# this work for additional information regarding copyright ownership.
+# The ASF licenses this file to You under the Apache License, Version 2.0
+# (the "License"); you may not use this file except in compliance with
+# the License.  You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+SUPPORTED_BITS_PER_VALUE = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 16, 21, 32]
+
+HEADER="""// This file has been automatically generated, DO NOT EDIT
+
+package org.apache.lucene.util.packed;
+
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with this
+ * work for additional information regarding copyright ownership. The ASF
+ * licenses this file to You under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations under
+ * the License.
+ */
+
+import java.io.IOException;
+import java.util.Arrays;
+
+import org.apache.lucene.store.DataInput;
+import org.apache.lucene.util.RamUsageEstimator;
+
+/**
+ * This class is similar to {@link Packed64} except that it trades space for
+ * speed by ensuring that a single block needs to be read/written in order to
+ * read/write a value.
+ */
+abstract class Packed64SingleBlock extends PackedInts.MutableImpl {
+
+  public static final int MAX_SUPPORTED_BITS_PER_VALUE = %d;
+  private static final int[] SUPPORTED_BITS_PER_VALUE = new int[] {%s};
+
+  public static boolean isSupported(int bitsPerValue) {
+    return Arrays.binarySearch(SUPPORTED_BITS_PER_VALUE, bitsPerValue) >= 0;
+  }
+
+  public static float overheadPerValue(int bitsPerValue) {
+    int valuesPerBlock = 64 / bitsPerValue;
+    int overhead = 64 %% bitsPerValue;
+    return (float) overhead / valuesPerBlock;
+  }
+
+  private static int requiredCapacity(int valueCount, int valuesPerBlock) {
+    return valueCount / valuesPerBlock
+        + (valueCount %% valuesPerBlock == 0 ? 0 : 1);
+  }
+
+  final long[] blocks;
+
+  Packed64SingleBlock(int valueCount, int bitsPerValue) {
+    super(valueCount, bitsPerValue);
+    assert isSupported(bitsPerValue);
+    final int valuesPerBlock = 64 / bitsPerValue;
+    blocks = new long[requiredCapacity(valueCount, valuesPerBlock)];
+  }
+
+  @Override
+  public void clear() {
+    Arrays.fill(blocks, 0L);
+  }
+
+  public long ramBytesUsed() {
+    return RamUsageEstimator.sizeOf(blocks);
+  }
+
+  @Override
+  public int get(int index, long[] arr, int off, int len) {
+    assert len > 0 : "len must be > 0 (got " + len + ")";
+    assert index >= 0 && index < valueCount;
+    len = Math.min(len, valueCount - index);
+    assert off + len <= arr.length;
+
+    final int originalIndex = index;
+
+    // go to the next block boundary
+    final int valuesPerBlock = 64 / bitsPerValue;
+    final int offsetInBlock = index %% valuesPerBlock;
+    if (offsetInBlock != 0) {
+      for (int i = offsetInBlock; i < valuesPerBlock && len > 0; ++i) {
+        arr[off++] = get(index++);
+        --len;
+      }
+      if (len == 0) {
+        return index - originalIndex;
+      }
+    }
+
+    // bulk get
+    assert index %% valuesPerBlock == 0;
+    final long readMask = (1L << bitsPerValue) - 1;
+    final int startBlock = index / valuesPerBlock;
+    final int endBlock = (index + len) / valuesPerBlock;
+    final int diff = (endBlock - startBlock) * valuesPerBlock;
+    index += diff; len -= diff;
+    for (int block = startBlock; block < endBlock; ++block) {
+      for (int i = 0; i < valuesPerBlock; ++i) {
+        arr[off++] = (blocks[block] >>> (i * bitsPerValue)) & readMask;
+      }
+    }
+
+    if (index > originalIndex) {
+      // stay at the block boundary
+      return index - originalIndex;
+    } else {
+      // no progress so far => already at a block boundary but no full block to
+      // get
+      assert index == originalIndex;
+      return super.get(index, arr, off, len);
+    }
+  }
+
+  @Override
+  public int set(int index, long[] arr, int off, int len) {
+    assert len > 0 : "len must be > 0 (got " + len + ")";
+    assert index >= 0 && index < valueCount;
+    len = Math.min(len, valueCount - index);
+    assert off + len <= arr.length;
+
+    final int originalIndex = index;
+
+    // go to the next block boundary
+    final int valuesPerBlock = 64 / bitsPerValue;
+    final int offsetInBlock = index %% valuesPerBlock;
+    if (offsetInBlock != 0) {
+      for (int i = offsetInBlock; i < valuesPerBlock && len > 0; ++i) {
+        set(index++, arr[off++]);
+        --len;
+      }
+      if (len == 0) {
+        return index - originalIndex;
+      }
+    }
+
+    // bulk set
+    assert index %% valuesPerBlock == 0;
+    final int startBlock = index / valuesPerBlock;
+    final int endBlock = (index + len) / valuesPerBlock;
+    final int diff = (endBlock - startBlock) * valuesPerBlock;
+    index += diff; len -= diff;
+    for (int block = startBlock; block < endBlock; ++block) {
+      long next = 0L;
+      for (int i = 0; i < valuesPerBlock; ++i) {
+        next |= (arr[off++] << (i * bitsPerValue));
+      }
+      blocks[block] = next;
+    }
+
+    if (index > originalIndex) {
+      // stay at the block boundary
+      return index - originalIndex;
+    } else {
+      // no progress so far => already at a block boundary but no full block to
+      // set
+      assert index == originalIndex;
+      return super.set(index, arr, off, len);
+    }
+  }
+
+  @Override
+  public void fill(int fromIndex, int toIndex, long val) {
+    assert fromIndex >= 0;
+    assert fromIndex <= toIndex;
+    assert PackedInts.bitsRequired(val) <= bitsPerValue;
+
+    final int valuesPerBlock = 64 / bitsPerValue;
+    if (toIndex - fromIndex <= valuesPerBlock << 1) {
+      // there needs to be at least one full block to set for the block
+      // approach to be worth trying
+      super.fill(fromIndex, toIndex, val);
+      return;
+    }
+
+    // set values naively until the next block start
+    int fromOffsetInBlock = fromIndex %% valuesPerBlock;
+    if (fromOffsetInBlock != 0) {
+      for (int i = fromOffsetInBlock; i < valuesPerBlock; ++i) {
+        set(fromIndex++, val);
+      }
+      assert fromIndex %% valuesPerBlock == 0;
+    }
+
+    // bulk set of the inner blocks
+    final int fromBlock = fromIndex / valuesPerBlock;
+    final int toBlock = toIndex / valuesPerBlock;
+    assert fromBlock * valuesPerBlock == fromIndex;
+
+    long blockValue = 0L;
+    for (int i = 0; i < valuesPerBlock; ++i) {
+      blockValue = blockValue | (val << (i * bitsPerValue));
+    }
+    Arrays.fill(blocks, fromBlock, toBlock, blockValue);
+
+    // fill the gap
+    for (int i = valuesPerBlock * toBlock; i < toIndex; ++i) {
+      set(i, val);
+    }
+  }
+
+  @Override
+  protected int getFormat() {
+    return PackedInts.PACKED_SINGLE_BLOCK;
+  }
+
+  @Override
+  public String toString() {
+    return getClass().getSimpleName() + "(bitsPerValue=" + bitsPerValue
+        + ", size=" + size() + ", elements.length=" + blocks.length + ")";
+  }
+
+  public static Packed64SingleBlock create(DataInput in,
+      int valueCount, int bitsPerValue) throws IOException {
+    Packed64SingleBlock reader = create(valueCount, bitsPerValue);
+    for (int i = 0; i < reader.blocks.length; ++i) {
+      reader.blocks[i] = in.readLong();
+    }
+    return reader;
+  }
+
+""" %(SUPPORTED_BITS_PER_VALUE[-1], ", ".join(map(str, SUPPORTED_BITS_PER_VALUE)))
+
+FOOTER = "}"
+
+if __name__ == '__main__':
+
+  f = open("Packed64SingleBlock.java", 'w')
+  f.write(HEADER)
+  f.write("  public static Packed64SingleBlock create(int valueCount, int bitsPerValue) {\n")
+  f.write("    switch (bitsPerValue) {\n")
+  for bpv in SUPPORTED_BITS_PER_VALUE:
+    f.write("      case %d:\n" %bpv)
+    f.write("        return new Packed64SingleBlock%d(valueCount);\n" %bpv)
+  f.write("      default:\n")
+  f.write("        throw new IllegalArgumentException(\"Unsupported number of bits per value: \" + %d);\n" %bpv)
+  f.write("    }\n")
+  f.write("  }\n\n")
+
+  for bpv in SUPPORTED_BITS_PER_VALUE:
+    log_2 = 0
+    while (1 << log_2) < bpv:
+      log_2 = log_2 + 1
+    if (1 << log_2) != bpv:
+      log_2 = None
+
+    f.write("  static class Packed64SingleBlock%d extends Packed64SingleBlock {\n\n" %bpv)
+
+    f.write("    Packed64SingleBlock%d(int valueCount) {\n" %bpv)
+    f.write("      super(valueCount, %d);\n" %bpv)
+    f.write("    }\n\n")
+
+    f.write("    @Override\n")
+    f.write("    public long get(int index) {\n")
+    if log_2 is not None:
+      f.write("      final int o = index >>> %d;\n" %(6 - log_2))
+      f.write("      final int b = index & %d;\n" %((1 << (6 - log_2)) - 1))
+      f.write("      final int shift = b << %d;\n" %log_2)
+    else:
+      f.write("      final int o = index / %d;\n" %(64 / bpv))
+      f.write("      final int b = index %% %d;\n" %(64 / bpv))
+      f.write("      final int shift = b * %d;\n" %bpv)
+    f.write("      return (blocks[o] >>> shift) & %dL;\n" %((1 << bpv) - 1))
+    f.write("    }\n\n")
+
+    f.write("    @Override\n")
+    f.write("    public void set(int index, long value) {\n")
+    if log_2 is not None:
+      f.write("      final int o = index >>> %d;\n" %(6 - log_2))
+      f.write("      final int b = index & %d;\n" %((1 << (6 - log_2)) - 1))
+      f.write("      final int shift = b << %d;\n" %log_2)
+    else:
+      f.write("      final int o = index / %d;\n" %(64 / bpv))
+      f.write("      final int b = index %% %d;\n" %(64 / bpv))
+      f.write("      final int shift = b * %d;\n" %bpv)
+    f.write("      blocks[o] = (blocks[o] & ~(%dL << shift)) | (value << shift);\n" % ((1 << bpv) - 1))
+    f.write("    }\n\n")
+    f.write("  }\n\n")
+
+  f.write(FOOTER)
+  f.close()