sc/inc/arraysumfunctor.hxx

   1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
   2 /*
   3  * This file is part of the LibreOffice project.
   4  *
   5  * This Source Code Form is subject to the terms of the Mozilla Public
   6  * License, v. 2.0. If a copy of the MPL was not distributed with this
   7  * file, You can obtain one at http://mozilla.org/MPL/2.0/.
   8  *
   9  */
  10
  11 #pragma once
  12
  13 #include <cmath>
  14 #include "kahan.hxx"
  15 #include <formula/errorcodes.hxx>
  16
  17 namespace sc::op
  18 {
  19 /**
  20   * If no boosts available, Unrolled KahanSum.
  21   */
  22 static inline KahanSum executeUnrolled(size_t& i, size_t nSize, const double* pCurrent)
  23 {
  24     size_t nRealSize = nSize - i;
  25     size_t nUnrolledSize = nRealSize - (nRealSize % 4);
  26
  27     if (nUnrolledSize > 0)
  28     {
  29         KahanSum sum0 = 0.0;
  30         KahanSum sum1 = 0.0;
  31         KahanSum sum2 = 0.0;
  32         KahanSum sum3 = 0.0;
  33
  34         for (; i + 3 < nUnrolledSize; i += 4)
  35         {
  36             sum0 += *pCurrent++;
  37             sum1 += *pCurrent++;
  38             sum2 += *pCurrent++;
  39             sum3 += *pCurrent++;
  40         }
  41         // We are using pairwise summation alongside Kahan
  42         return (sum0 + sum1) + (sum2 + sum3);
  43     }
  44     return 0.0;
  45 }
  46
  47 /**
  48   * This function task is to choose the fastest method available to perform the sum.
  49   * @param i
  50   * @param nSize
  51   * @param pCurrent
  52   */
  53 static inline KahanSum executeFast(size_t& i, size_t nSize, const double* pCurrent)
  54 {
  55 #if SC_USE_SSE2
  56     return executeSSE2(i, nSize, pCurrent);
  57 #else
  58     return executeUnrolled(i, nSize, pCurrent);
  59 #endif
  60 }
  61
  62 /**
  63   * Performs the sum of an array.
  64   * Note that align 16 will speed up the process.
  65   * @param pArray
  66   * @param nSize
  67   */
  68 inline KahanSum sumArray(const double* pArray, size_t nSize)
  69 {
  70     size_t i = 0;
  71     const double* pCurrent = pArray;
  72     KahanSum fSum = executeFast(i, nSize, pCurrent);
  73
  74     // sum rest of the array
  75     for (; i < nSize; ++i)
  76         fSum += pArray[i];
  77
  78     // If the sum is a NaN, some of the terms were empty cells, probably.
  79     // Re-calculate, carefully
  80     double fVal = fSum.get();
  81     if (!std::isfinite(fVal))
  82     {
  83         FormulaError nErr = GetDoubleErrorValue(fVal);
  84         if (nErr == FormulaError::NoValue)
  85         {
  86             fSum = 0;
  87             for (i = 0; i < nSize; i++)
  88             {
  89                 if (!std::isfinite(pArray[i]))
  90                 {
  91                     nErr = GetDoubleErrorValue(pArray[i]);
  92                     if (nErr != FormulaError::NoValue)
  93                         fSum += pArray[i]; // Let errors encoded as NaNs propagate ???
  94                 }
  95                 else
  96                     fSum += pArray[i];
  97             }
  98         }
  99     }
 100     return fSum;
 101 }
 102
 103 } // end namespace sc::op
 104
 105 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */