/* ====================================================================
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Licensed to the Apache Software Foundation (ASF) under one or more
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contributor license agreements. See the NOTICE file distributed with
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this work for Additional information regarding copyright ownership.
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The ASF licenses this file to You under the Apache License, Version 2.0
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(the "License"); you may not use this file except in compliance with
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the License. You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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==================================================================== */
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using System;
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namespace HH.WMS.Utils.NPOI.SS.Util
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{
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using HH.WMS.Utils.NPOI.Util;
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/*
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* Represents a 64 bit IEEE double quantity expressed with both decimal and binary exponents
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* Does not handle negative numbers or zero
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* <p/>
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* The value of a {@link ExpandedDouble} is given by<br/>
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* <c> a × 2<sup>b</sup></c>
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* <br/>
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* where:<br/>
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*
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* <c>a</c> = <i>significand</i><br/>
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* <c>b</c> = <i>binaryExponent</i> - bitLength(significand) + 1<br/>
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*
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* @author Josh Micich
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*/
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public class ExpandedDouble
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{
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private static BigInteger BI_FRAC_MASK = new BigInteger(IEEEDouble.FRAC_MASK);
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private static BigInteger BI_IMPLIED_FRAC_MSB = new BigInteger(IEEEDouble.FRAC_ASSUMED_HIGH_BIT);
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private static BigInteger GetFrac(long rawBits)
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{
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return (new BigInteger(rawBits)&BI_FRAC_MASK|BI_IMPLIED_FRAC_MSB)<<11;
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}
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public static ExpandedDouble FromRawBitsAndExponent(long rawBits, int exp)
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{
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return new ExpandedDouble(GetFrac(rawBits), exp);
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}
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/**
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* Always 64 bits long (MSB, bit-63 is '1')
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*/
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private BigInteger _significand;
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private int _binaryExponent;
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public ExpandedDouble(long rawBits)
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{
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int biasedExp = (int)(rawBits >> 52);
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if (biasedExp == 0)
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{
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// sub-normal numbers
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BigInteger frac = new BigInteger(rawBits)&BI_FRAC_MASK;
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int expAdj = 64 - frac.BitLength();
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_significand = frac<<expAdj;
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_binaryExponent = (biasedExp & 0x07FF) - 1023 - expAdj;
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}
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else
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{
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BigInteger frac = GetFrac(rawBits);
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_significand = frac;
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_binaryExponent = (biasedExp & 0x07FF) - 1023;
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}
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}
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public ExpandedDouble(BigInteger frac, int binaryExp)
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{
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if (frac.BitLength() != 64)
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{
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throw new ArgumentException("bad bit length");
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}
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_significand = frac;
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_binaryExponent = binaryExp;
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}
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/**
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* Convert to an equivalent {@link NormalisedDecimal} representation having 15 decimal digits of precision in the
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* non-fractional bits of the significand.
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*/
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public NormalisedDecimal NormaliseBaseTen()
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{
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return NormalisedDecimal.Create(_significand, _binaryExponent);
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}
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/**
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* @return the number of non-fractional bits after the MSB of the significand
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*/
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public int GetBinaryExponent()
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{
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return _binaryExponent;
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}
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public BigInteger GetSignificand()
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{
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return _significand;
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}
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}
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}
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