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