/*
* 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;
import java.util.Arrays;
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);
}
}
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);
}
}
public void testInt4() {
for (int i = 0; i <= 16; ++i) {
// all values in 0-16 are encoded accurately
assertEquals(i, SmallFloat.int4ToLong(SmallFloat.longToInt4(i)));
}
final int maxEncoded = SmallFloat.longToInt4(Long.MAX_VALUE);
for (int i = 1; i < maxEncoded; ++i) {
assertTrue(SmallFloat.int4ToLong(i) > SmallFloat.int4ToLong(i - 1));
}
final int iters = atLeast(1000);
for (int iter = 0; iter < iters; ++iter) {
final long l = TestUtil.nextLong(random(), 0, 1L << TestUtil.nextInt(random(), 5, 61));
int numBits = 64 - Long.numberOfLeadingZeros(l);
long expected = l;
if (numBits > 4) {
long mask = ~0L << (numBits - 4);
expected &= mask;
}
long l2 = SmallFloat.int4ToLong(SmallFloat.longToInt4(l));
assertEquals(expected, l2);
}
}
public void testByte4() {
int[] decoded = new int[256];
for (int b = 0; b < 256; ++b) {
decoded[b] = SmallFloat.byte4ToInt((byte) b);
assertEquals((byte) b, SmallFloat.intToByte4(decoded[b]));
}
for (int i = 1; i < 256; ++i) {
assertTrue(decoded[i] > decoded[i-1]);
}
assertEquals((byte) 255, SmallFloat.intToByte4(Integer.MAX_VALUE));
final int iters = atLeast(1000);
for (int iter = 0; iter < iters; ++iter) {
final int i = random().nextInt(1 << TestUtil.nextInt(random(), 5, 30));
int idx = Arrays.binarySearch(decoded, i);
if (idx < 0) {
idx = -2 - idx;
}
assertTrue(decoded[idx] <= i);
assertEquals((byte) idx, SmallFloat.intToByte4(i));
}
}
/***
// 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;
}
}
***/
}