| /* |
| * 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; |
| } |
| } |
| ***/ |
| } |