svn commit: r1073998 - /lucene/dev/branches/branch_3x/lucene/backwards/src/test/org/apache/lucene/util/TestSmallFloat.java

[yo...@apache.org]

Author: yonik
Date: Thu Feb 24 00:36:08 2011
New Revision: 1073998

URL: http://svn.apache.org/viewvc?rev=1073998&view=rev
Log:
LUCENE-2937: fix backwards tests

Modified:
    lucene/dev/branches/branch_3x/lucene/backwards/src/test/org/apache/lucene/util/TestSmallFloat.java

Modified: lucene/dev/branches/branch_3x/lucene/backwards/src/test/org/apache/lucene/util/TestSmallFloat.java
URL: http://svn.apache.org/viewvc/lucene/dev/branches/branch_3x/lucene/backwards/src/test/org/apache/lucene/util/TestSmallFloat.java?rev=1073998&r1=1073997&r2=1073998&view=diff
==============================================================================
--- lucene/dev/branches/branch_3x/lucene/backwards/src/test/org/apache/lucene/util/TestSmallFloat.java (original)
+++ lucene/dev/branches/branch_3x/lucene/backwards/src/test/org/apache/lucene/util/TestSmallFloat.java Thu Feb 24 00:36:08 2011
@@ -33,8 +33,8 @@ public class TestSmallFloat extends Luce
     return Float.intBitsToFloat(bits);
   }
 
-  // original lucene floatToByte
-  static byte orig_floatToByte(float f) {
+  // 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;
 
@@ -58,6 +58,33 @@ public class TestSmallFloat extends Luce
     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);