core/cubic_tables.cpp

   1
   2 #include "cubic_tables.h"
   3
   4 #include <algorithm>
   5 #include <array>
   6 #include <cassert>
   7 #include <cmath>
   8 #include <limits>
   9 #include <memory>
  10 #include <stdexcept>
  11
  12 #include "alnumbers.h"
  13 #include "core/mixer/defs.h"
  14
  15
  16 namespace {
  17
  18 using uint = unsigned int;
  19
  20 struct SplineFilterArray {
  21     alignas(16) CubicCoefficients mTable[CubicPhaseCount]{};
  22
  23     constexpr SplineFilterArray()
  24     {
  25         /* Fill in the main coefficients. */
  26         for(size_t pi{0};pi < CubicPhaseCount;++pi)
  27         {
  28             const double mu{static_cast<double>(pi) / CubicPhaseCount};
  29             const double mu2{mu*mu}, mu3{mu2*mu};
  30             mTable[pi].mCoeffs[0] = static_cast<float>(-0.5*mu3 +      mu2 + -0.5*mu);
  31             mTable[pi].mCoeffs[1] = static_cast<float>( 1.5*mu3 + -2.5*mu2           + 1.0);
  32             mTable[pi].mCoeffs[2] = static_cast<float>(-1.5*mu3 +  2.0*mu2 +  0.5*mu);
  33             mTable[pi].mCoeffs[3] = static_cast<float>( 0.5*mu3 + -0.5*mu2);
  34         }
  35
  36         /* Fill in the coefficient deltas. */
  37         for(size_t pi{0};pi < CubicPhaseCount-1;++pi)
  38         {
  39             mTable[pi].mDeltas[0] = mTable[pi+1].mCoeffs[0] - mTable[pi].mCoeffs[0];
  40             mTable[pi].mDeltas[1] = mTable[pi+1].mCoeffs[1] - mTable[pi].mCoeffs[1];
  41             mTable[pi].mDeltas[2] = mTable[pi+1].mCoeffs[2] - mTable[pi].mCoeffs[2];
  42             mTable[pi].mDeltas[3] = mTable[pi+1].mCoeffs[3] - mTable[pi].mCoeffs[3];
  43         }
  44
  45         const size_t pi{CubicPhaseCount - 1};
  46         mTable[pi].mDeltas[0] = -mTable[pi].mCoeffs[0];
  47         mTable[pi].mDeltas[1] = -mTable[pi].mCoeffs[1];
  48         mTable[pi].mDeltas[2] = 1.0f - mTable[pi].mCoeffs[2];
  49         mTable[pi].mDeltas[3] = -mTable[pi].mCoeffs[3];
  50     }
  51
  52     constexpr auto getTable() const noexcept { return al::as_span(mTable); }
  53 };
  54
  55 constexpr SplineFilterArray SplineFilter{};
  56
  57 } // namespace
  58
  59 const CubicTable gCubicSpline{SplineFilter.getTable()};