pylucene 3.5.0-3

[pylucene.git] / lucene-java-3.5.0 / lucene / src / test / org / apache / lucene / util / TestBitUtil.java

diff --git a/lucene-java-3.5.0/lucene/src/test/org/apache/lucene/util/TestBitUtil.java b/lucene-java-3.5.0/lucene/src/test/org/apache/lucene/util/TestBitUtil.java
new file mode 100644 (file)
index 0000000..67e1b15
--- /dev/null
+++ b/lucene-java-3.5.0/lucene/src/test/org/apache/lucene/util/TestBitUtil.java
@@ -0,0 +1,133 @@
+/**
+ * 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.
+ */
+
+package org.apache.lucene.util;
+
+public class TestBitUtil extends LuceneTestCase {
+
+  private static int slowNlz(long x) {
+    if (x == 0L) return 64;
+    int nlz = 0;
+    while ( ((x << nlz) & (1L << 63)) == 0) {
+      nlz++;
+    }
+    return nlz;
+  }
+
+  private void checkNlz(long x) {
+    assertEquals(slowNlz(x), BitUtil.nlz(x));
+    assertEquals(Long.numberOfLeadingZeros(x), BitUtil.nlz(x));
+  }
+  
+  public void testNlz() {
+    checkNlz(0L);
+    checkNlz(1L);
+    checkNlz(-1L);
+    for (int i = 1; i <= 63; i++) {
+      checkNlz(1L << i);
+      checkNlz((1L << i) + (1L << (i>>1)));
+    }
+  }
+
+  public void testBitUtils() {
+    long num = 100000;
+    assertEquals( 5, BitUtil.ntz(num) );
+    assertEquals( 5, BitUtil.ntz2(num) );
+    assertEquals( 5, BitUtil.ntz3(num) );
+    
+    num = 10;
+    assertEquals( 1, BitUtil.ntz(num) );
+    assertEquals( 1, BitUtil.ntz2(num) );
+    assertEquals( 1, BitUtil.ntz3(num) );
+
+    for (int i=0; i<64; i++) {
+      num = 1L << i;
+      assertEquals( i, BitUtil.ntz(num) );
+      assertEquals( i, BitUtil.ntz2(num) );
+      assertEquals( i, BitUtil.ntz3(num) );
+    }
+  }
+
+
+  private long testArg(int shift) {
+    return (1L << shift) + (1L << (shift>>1));
+  }
+  
+  private long nlzBitUtilBasicLoop(int iters) {
+    long sumRes = 0;
+    while (iters-- >= 0) {
+      for (int i = 1; i <= 63; i++) {
+       long a = testArg(i);
+       sumRes += BitUtil.nlz(a);
+       sumRes += BitUtil.nlz(a+1);
+       sumRes += BitUtil.nlz(a-1);
+       sumRes += BitUtil.nlz(a+10);
+       sumRes += BitUtil.nlz(a-10);
+      }
+    }
+    return sumRes;
+  }
+    
+  private long nlzLongBasicLoop(int iters) {
+    long sumRes = 0;
+    while (iters-- >= 0) {
+      for (int i = 1; i <= 63; i++) {
+       long a = testArg(i);
+       sumRes += Long.numberOfLeadingZeros(a);
+       sumRes += Long.numberOfLeadingZeros(a+1);
+       sumRes += Long.numberOfLeadingZeros(a-1);
+       sumRes += Long.numberOfLeadingZeros(a+10);
+       sumRes += Long.numberOfLeadingZeros(a-10);
+      }
+    }
+    return sumRes;
+  }
+
+  public void tstPerfNlz() { // See LUCENE-3197, prefer to use Long.numberOfLeadingZeros() over BitUtil.nlz().
+    final long measureMilliSecs = 2000;
+    final int basicIters = 100000;
+    long startTime;
+    long endTime;
+    long curTime;
+    long dummy = 0; // avoid optimizing away
+
+    dummy = 0;
+    int bitUtilLoops = 0;
+    startTime = System.currentTimeMillis();
+    endTime = startTime + measureMilliSecs;
+    do {
+      dummy += nlzBitUtilBasicLoop(basicIters);
+      bitUtilLoops++;
+      curTime = System.currentTimeMillis();
+    } while (curTime < endTime);
+    int bitUtilPsTime = (int) (1000000000 * (curTime - startTime) / (basicIters * 5 * 63 * (float) bitUtilLoops));
+    System.out.println("BitUtil nlz time: " + (bitUtilPsTime/1) + " picosec/call, dummy: " + dummy);
+
+
+    dummy = 0;
+    int longLoops = 0;
+    startTime = System.currentTimeMillis();
+    endTime = startTime + measureMilliSecs;
+    do {
+      dummy += nlzLongBasicLoop(basicIters);
+      longLoops++;
+      curTime = System.currentTimeMillis();
+    } while (curTime < endTime);
+    int longPsTime = (int) (1000000000 * (curTime - startTime) / (basicIters * 5 * 63 * (float) longLoops));
+    System.out.println("Long    nlz time: " + longPsTime + " picosec/call, dummy: " + dummy);
+  }
+}