105 lines
2.7 KiB
C++
105 lines
2.7 KiB
C++
/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
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/*
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* This file is part of the LibreOffice project.
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*
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/.
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*
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*/
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#pragma once
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#include <cmath>
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#include "kahan.hxx"
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#include <formula/errorcodes.hxx>
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namespace sc::op
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{
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/**
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* If no boosts available, Unrolled KahanSum.
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*/
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static inline KahanSum executeUnrolled(size_t& i, size_t nSize, const double* pCurrent)
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{
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size_t nRealSize = nSize - i;
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size_t nUnrolledSize = nRealSize - (nRealSize % 4);
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if (nUnrolledSize > 0)
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{
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KahanSum sum0 = 0.0;
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KahanSum sum1 = 0.0;
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KahanSum sum2 = 0.0;
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KahanSum sum3 = 0.0;
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for (; i + 3 < nUnrolledSize; i += 4)
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{
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sum0 += *pCurrent++;
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sum1 += *pCurrent++;
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sum2 += *pCurrent++;
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sum3 += *pCurrent++;
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}
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// We are using pairwise summation alongside Kahan
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return (sum0 + sum1) + (sum2 + sum3);
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}
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return 0.0;
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}
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/**
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* This function task is to choose the fastest method available to perform the sum.
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* @param i
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* @param nSize
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* @param pCurrent
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*/
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static inline KahanSum executeFast(size_t& i, size_t nSize, const double* pCurrent)
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{
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#if SC_USE_SSE2
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return executeSSE2(i, nSize, pCurrent);
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#else
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return executeUnrolled(i, nSize, pCurrent);
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#endif
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}
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/**
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* Performs the sum of an array.
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* Note that align 16 will speed up the process.
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* @param pArray
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* @param nSize
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*/
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inline KahanSum sumArray(const double* pArray, size_t nSize)
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{
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size_t i = 0;
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const double* pCurrent = pArray;
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KahanSum fSum = executeFast(i, nSize, pCurrent);
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// sum rest of the array
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for (; i < nSize; ++i)
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fSum += pArray[i];
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// If the sum is a NaN, some of the terms were empty cells, probably.
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// Re-calculate, carefully
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double fVal = fSum.get();
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if (!std::isfinite(fVal))
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{
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FormulaError nErr = GetDoubleErrorValue(fVal);
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if (nErr == FormulaError::NoValue)
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{
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fSum = 0;
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for (i = 0; i < nSize; i++)
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{
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if (!std::isfinite(pArray[i]))
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{
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nErr = GetDoubleErrorValue(pArray[i]);
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if (nErr != FormulaError::NoValue)
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fSum += pArray[i]; // Let errors encoded as NaNs propagate ???
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}
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else
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fSum += pArray[i];
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}
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}
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}
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return fSum;
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}
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} // end namespace sc::op
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/* vim:set shiftwidth=4 softtabstop=4 expandtab: */
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