| /* ==================================================================== |
| 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.poi.ss.util; |
| |
| import java.math.BigInteger; |
| import static org.apache.poi.ss.util.IEEEDouble.*; |
| |
| /** |
| * Represents a 64 bit IEEE double quantity expressed with both decimal and binary exponents |
| * Does not handle negative numbers or zero |
| * <p> |
| * The value of a {@link ExpandedDouble} is given by<br> |
| * <tt> a × 2<sup>b</sup></tt> |
| * <br> |
| * where:<br> |
| * |
| * <tt>a</tt> = <i>significand</i><br> |
| * <tt>b</tt> = <i>binaryExponent</i> - bitLength(significand) + 1<br> |
| * |
| * @author Josh Micich |
| */ |
| final class ExpandedDouble { |
| private static final BigInteger BI_FRAC_MASK = BigInteger.valueOf(FRAC_MASK); |
| private static final BigInteger BI_IMPLIED_FRAC_MSB = BigInteger.valueOf(FRAC_ASSUMED_HIGH_BIT); |
| |
| private static BigInteger getFrac(long rawBits) { |
| return BigInteger.valueOf(rawBits).and(BI_FRAC_MASK).or(BI_IMPLIED_FRAC_MSB).shiftLeft(11); |
| } |
| |
| |
| public static ExpandedDouble fromRawBitsAndExponent(long rawBits, int exp) { |
| return new ExpandedDouble(getFrac(rawBits), exp); |
| } |
| |
| /** |
| * Always 64 bits long (MSB, bit-63 is '1') |
| */ |
| private final BigInteger _significand; |
| private final int _binaryExponent; |
| |
| public ExpandedDouble(long rawBits) { |
| int biasedExp = Math.toIntExact(rawBits >> 52); |
| if (biasedExp == 0) { |
| // sub-normal numbers |
| BigInteger frac = BigInteger.valueOf(rawBits).and(BI_FRAC_MASK); |
| int expAdj = 64 - frac.bitLength(); |
| _significand = frac.shiftLeft(expAdj); |
| _binaryExponent = (biasedExp & 0x07FF) - 1023 - expAdj; |
| } else { |
| _significand = getFrac(rawBits); |
| _binaryExponent = (biasedExp & 0x07FF) - 1023; |
| } |
| } |
| |
| ExpandedDouble(BigInteger frac, int binaryExp) { |
| if (frac.bitLength() != 64) { |
| throw new IllegalArgumentException("bad bit length"); |
| } |
| _significand = frac; |
| _binaryExponent = binaryExp; |
| } |
| |
| |
| /** |
| * Convert to an equivalent {@link NormalisedDecimal} representation having 15 decimal digits of precision in the |
| * non-fractional bits of the significand. |
| */ |
| public NormalisedDecimal normaliseBaseTen() { |
| return NormalisedDecimal.create(_significand, _binaryExponent); |
| } |
| |
| /** |
| * @return the number of non-fractional bits after the MSB of the significand |
| */ |
| public int getBinaryExponent() { |
| return _binaryExponent; |
| } |
| |
| public BigInteger getSignificand() { |
| return _significand; |
| } |
| } |