pylucene 3.5.0-3

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

diff --git a/lucene-java-3.5.0/lucene/src/test/org/apache/lucene/util/TestSmallFloat.java b/lucene-java-3.5.0/lucene/src/test/org/apache/lucene/util/TestSmallFloat.java
new file mode 100644 (file)
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+++ b/lucene-java-3.5.0/lucene/src/test/org/apache/lucene/util/TestSmallFloat.java
@@ -0,0 +1,150 @@
+package org.apache.lucene.util;
+
+/**
+ * Copyright 2005 The Apache Software Foundation
+ *
+ * Licensed 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.
+ */
+
+public class TestSmallFloat extends LuceneTestCase {
+
+  // original lucene byteToFloat
+  static float orig_byteToFloat(byte b) {
+    if (b == 0)                                   // zero is a special case
+      return 0.0f;
+    int mantissa = b & 7;
+    int exponent = (b >> 3) & 31;
+    int bits = ((exponent+(63-15)) << 24) | (mantissa << 21);
+    return Float.intBitsToFloat(bits);
+  }
+
+  // original lucene floatToByte (since lucene 1.3)
+  static byte orig_floatToByte_v13(float f) {
+    if (f < 0.0f)                                 // round negatives up to zero
+      f = 0.0f;
+
+    if (f == 0.0f)                                // zero is a special case
+      return 0;
+
+    int bits = Float.floatToIntBits(f);           // parse float into parts
+    int mantissa = (bits & 0xffffff) >> 21;
+    int exponent = (((bits >> 24) & 0x7f) - 63) + 15;
+
+    if (exponent > 31) {                          // overflow: use max value
+      exponent = 31;
+      mantissa = 7;
+    }
+
+    if (exponent < 0) {                           // underflow: use min value
+      exponent = 0;
+      mantissa = 1;
+    }
+
+    return (byte)((exponent << 3) | mantissa);    // pack into a byte
+  }
+
+  // This is the original lucene floatToBytes (from v1.3)
+  // except with the underflow detection bug fixed for values like 5.8123817E-10f
+  static byte orig_floatToByte(float f) {
+    if (f < 0.0f)                                 // round negatives up to zero
+      f = 0.0f;
+
+    if (f == 0.0f)                                // zero is a special case
+      return 0;
+
+    int bits = Float.floatToIntBits(f);           // parse float into parts
+    int mantissa = (bits & 0xffffff) >> 21;
+    int exponent = (((bits >> 24) & 0x7f) - 63) + 15;
+
+    if (exponent > 31) {                          // overflow: use max value
+      exponent = 31;
+      mantissa = 7;
+    }
+
+    if (exponent < 0 || exponent == 0 && mantissa == 0) { // underflow: use min value
+      exponent = 0;
+      mantissa = 1;
+    }
+
+    return (byte)((exponent << 3) | mantissa);    // pack into a byte
+  }
+
+
+  public void testByteToFloat() {
+    for (int i=0; i<256; i++) {
+      float f1 = orig_byteToFloat((byte)i);
+      float f2 = SmallFloat.byteToFloat((byte)i, 3,15);
+      float f3 = SmallFloat.byte315ToFloat((byte)i);
+      assertEquals(f1,f2,0.0);
+      assertEquals(f2,f3,0.0);
+
+      float f4 = SmallFloat.byteToFloat((byte)i,5,2);
+      float f5 = SmallFloat.byte52ToFloat((byte)i);
+      assertEquals(f4,f5,0.0);
+    }
+  }
+
+  public void testFloatToByte() {
+    assertEquals(0, orig_floatToByte_v13(5.8123817E-10f));       // verify the old bug (see LUCENE-2937)
+    assertEquals(1, orig_floatToByte(5.8123817E-10f));           // verify it's fixed in this test code
+    assertEquals(1, SmallFloat.floatToByte315(5.8123817E-10f));  // verify it's fixed
+
+    // test some constants
+    assertEquals(0, SmallFloat.floatToByte315(0));
+    assertEquals(1, SmallFloat.floatToByte315(Float.MIN_VALUE));             // underflow rounds up to smallest positive
+    assertEquals(255, SmallFloat.floatToByte315(Float.MAX_VALUE) & 0xff);    // overflow rounds down to largest positive
+    assertEquals(255, SmallFloat.floatToByte315(Float.POSITIVE_INFINITY) & 0xff);
+
+    // all negatives map to 0
+    assertEquals(0, SmallFloat.floatToByte315(-Float.MIN_VALUE));
+    assertEquals(0, SmallFloat.floatToByte315(-Float.MAX_VALUE));
+    assertEquals(0, SmallFloat.floatToByte315(Float.NEGATIVE_INFINITY));
+
+
+    // up iterations for more exhaustive test after changing something
+    int num = atLeast(100000);
+    for (int i = 0; i < num; i++) {
+      float f = Float.intBitsToFloat(random.nextInt());
+      if (Float.isNaN(f)) continue;    // skip NaN
+      byte b1 = orig_floatToByte(f);
+      byte b2 = SmallFloat.floatToByte(f,3,15);
+      byte b3 = SmallFloat.floatToByte315(f);
+      assertEquals(b1,b2);
+      assertEquals(b2,b3);
+
+      byte b4 = SmallFloat.floatToByte(f,5,2);
+      byte b5 = SmallFloat.floatToByte52(f);
+      assertEquals(b4,b5);
+    }
+  }
+
+  /***
+  // Do an exhaustive test of all possible floating point values
+  // for the 315 float against the original norm encoding in Similarity.
+  // Takes 75 seconds on my Pentium4 3GHz, with Java5 -server
+  public void testAllFloats() {
+    for(int i = Integer.MIN_VALUE;;i++) {
+      float f = Float.intBitsToFloat(i);
+      if (f==f) { // skip non-numbers
+        byte b1 = orig_floatToByte(f);
+        byte b2 = SmallFloat.floatToByte315(f);
+        if (b1!=b2 || b2==0 && f>0) {
+          fail("Failed floatToByte315 for float " + f + " source bits="+Integer.toHexString(i) + " float raw bits=" + Integer.toHexString(Float.floatToRawIntBits(i)));
+        }
+      }
+      if (i==Integer.MAX_VALUE) break;
+    }
+  }
+  ***/
+
+}