1 package org.apache.lucene.util;
4 * Copyright 2005 The Apache Software Foundation
6 * Licensed under the Apache License, Version 2.0 (the "License");
7 * you may not use this file except in compliance with the License.
8 * You may obtain a copy of the License at
10 * http://www.apache.org/licenses/LICENSE-2.0
12 * Unless required by applicable law or agreed to in writing, software
13 * distributed under the License is distributed on an "AS IS" BASIS,
14 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15 * See the License for the specific language governing permissions and
16 * limitations under the License.
19 public class TestSmallFloat extends LuceneTestCase {
21 // original lucene byteToFloat
22 static float orig_byteToFloat(byte b) {
23 if (b == 0) // zero is a special case
26 int exponent = (b >> 3) & 31;
27 int bits = ((exponent+(63-15)) << 24) | (mantissa << 21);
28 return Float.intBitsToFloat(bits);
31 // original lucene floatToByte (since lucene 1.3)
32 static byte orig_floatToByte_v13(float f) {
33 if (f < 0.0f) // round negatives up to zero
36 if (f == 0.0f) // zero is a special case
39 int bits = Float.floatToIntBits(f); // parse float into parts
40 int mantissa = (bits & 0xffffff) >> 21;
41 int exponent = (((bits >> 24) & 0x7f) - 63) + 15;
43 if (exponent > 31) { // overflow: use max value
48 if (exponent < 0) { // underflow: use min value
53 return (byte)((exponent << 3) | mantissa); // pack into a byte
56 // This is the original lucene floatToBytes (from v1.3)
57 // except with the underflow detection bug fixed for values like 5.8123817E-10f
58 static byte orig_floatToByte(float f) {
59 if (f < 0.0f) // round negatives up to zero
62 if (f == 0.0f) // zero is a special case
65 int bits = Float.floatToIntBits(f); // parse float into parts
66 int mantissa = (bits & 0xffffff) >> 21;
67 int exponent = (((bits >> 24) & 0x7f) - 63) + 15;
69 if (exponent > 31) { // overflow: use max value
74 if (exponent < 0 || exponent == 0 && mantissa == 0) { // underflow: use min value
79 return (byte)((exponent << 3) | mantissa); // pack into a byte
83 public void testByteToFloat() {
84 for (int i=0; i<256; i++) {
85 float f1 = orig_byteToFloat((byte)i);
86 float f2 = SmallFloat.byteToFloat((byte)i, 3,15);
87 float f3 = SmallFloat.byte315ToFloat((byte)i);
88 assertEquals(f1,f2,0.0);
89 assertEquals(f2,f3,0.0);
91 float f4 = SmallFloat.byteToFloat((byte)i,5,2);
92 float f5 = SmallFloat.byte52ToFloat((byte)i);
93 assertEquals(f4,f5,0.0);
97 public void testFloatToByte() {
98 assertEquals(0, orig_floatToByte_v13(5.8123817E-10f)); // verify the old bug (see LUCENE-2937)
99 assertEquals(1, orig_floatToByte(5.8123817E-10f)); // verify it's fixed in this test code
100 assertEquals(1, SmallFloat.floatToByte315(5.8123817E-10f)); // verify it's fixed
102 // test some constants
103 assertEquals(0, SmallFloat.floatToByte315(0));
104 assertEquals(1, SmallFloat.floatToByte315(Float.MIN_VALUE)); // underflow rounds up to smallest positive
105 assertEquals(255, SmallFloat.floatToByte315(Float.MAX_VALUE) & 0xff); // overflow rounds down to largest positive
106 assertEquals(255, SmallFloat.floatToByte315(Float.POSITIVE_INFINITY) & 0xff);
108 // all negatives map to 0
109 assertEquals(0, SmallFloat.floatToByte315(-Float.MIN_VALUE));
110 assertEquals(0, SmallFloat.floatToByte315(-Float.MAX_VALUE));
111 assertEquals(0, SmallFloat.floatToByte315(Float.NEGATIVE_INFINITY));
114 // up iterations for more exhaustive test after changing something
115 int num = atLeast(100000);
116 for (int i = 0; i < num; i++) {
117 float f = Float.intBitsToFloat(random.nextInt());
118 if (Float.isNaN(f)) continue; // skip NaN
119 byte b1 = orig_floatToByte(f);
120 byte b2 = SmallFloat.floatToByte(f,3,15);
121 byte b3 = SmallFloat.floatToByte315(f);
125 byte b4 = SmallFloat.floatToByte(f,5,2);
126 byte b5 = SmallFloat.floatToByte52(f);
132 // Do an exhaustive test of all possible floating point values
133 // for the 315 float against the original norm encoding in Similarity.
134 // Takes 75 seconds on my Pentium4 3GHz, with Java5 -server
135 public void testAllFloats() {
136 for(int i = Integer.MIN_VALUE;;i++) {
137 float f = Float.intBitsToFloat(i);
138 if (f==f) { // skip non-numbers
139 byte b1 = orig_floatToByte(f);
140 byte b2 = SmallFloat.floatToByte315(f);
141 if (b1!=b2 || b2==0 && f>0) {
142 fail("Failed floatToByte315 for float " + f + " source bits="+Integer.toHexString(i) + " float raw bits=" + Integer.toHexString(Float.floatToRawIntBits(i)));
145 if (i==Integer.MAX_VALUE) break;