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/*
==============================================================================
This file is part of the JUCE library.
Copyright (c) 2017 - ROLI Ltd.
JUCE is an open source library subject to commercial or open-source
licensing.
By using JUCE, you agree to the terms of both the JUCE 5 End-User License
Agreement and JUCE 5 Privacy Policy (both updated and effective as of the
27th April 2017).
End User License Agreement: www.juce.com/juce-5-licence
Privacy Policy: www.juce.com/juce-5-privacy-policy
Or: You may also use this code under the terms of the GPL v3 (see
www.gnu.org/licenses).
JUCE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL WARRANTIES, WHETHER
EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS FOR PURPOSE, ARE
DISCLAIMED.
==============================================================================
*/
namespace juce
{
namespace dsp
{
template <typename FloatType>
static inline FloatType ncos (size_t order, size_t i, size_t size) noexcept
{
return std::cos (static_cast<FloatType> (order * i)
* MathConstants<FloatType>::pi / static_cast<FloatType> (size - 1));
}
template <typename FloatType>
WindowingFunction<FloatType>::WindowingFunction (size_t size, WindowingMethod type, bool normalise, FloatType beta)
{
fillWindowingTables (size, type, normalise, beta);
}
template <typename FloatType>
void WindowingFunction<FloatType>::fillWindowingTables (size_t size, WindowingMethod type,
bool normalise, FloatType beta) noexcept
{
windowTable.resize (static_cast<int> (size));
fillWindowingTables (windowTable.getRawDataPointer(), size, type, normalise, beta);
}
template <typename FloatType>
void WindowingFunction<FloatType>::fillWindowingTables (FloatType* samples, size_t size,
WindowingMethod type, bool normalise,
FloatType beta) noexcept
{
switch (type)
{
case rectangular:
{
for (size_t i = 0; i < size; ++i)
samples[i] = static_cast<FloatType> (1);
}
break;
case triangular:
{
auto halfSlots = static_cast<FloatType> (0.5) * static_cast<FloatType> (size - 1);
for (size_t i = 0; i < size; ++i)
samples[i] = static_cast<FloatType> (1.0) - std::abs ((static_cast<FloatType> (i) - halfSlots) / halfSlots);
}
break;
case hann:
{
for (size_t i = 0; i < size; ++i)
{
auto cos2 = ncos<FloatType> (2, i, size);
samples[i] = static_cast<FloatType> (0.5 - 0.5 * cos2);
}
}
break;
case hamming:
{
for (size_t i = 0; i < size; ++i)
{
auto cos2 = ncos<FloatType> (2, i, size);
samples[i] = static_cast<FloatType> (0.54 - 0.46 * cos2);
}
}
break;
case blackman:
{
constexpr FloatType alpha = 0.16f;
for (size_t i = 0; i < size; ++i)
{
auto cos2 = ncos<FloatType> (2, i, size);
auto cos4 = ncos<FloatType> (4, i, size);
samples[i] = static_cast<FloatType> (0.5 * (1 - alpha) - 0.5 * cos2 + 0.5 * alpha * cos4);
}
}
break;
case blackmanHarris:
{
for (size_t i = 0; i < size; ++i)
{
auto cos2 = ncos<FloatType> (2, i, size);
auto cos4 = ncos<FloatType> (4, i, size);
auto cos6 = ncos<FloatType> (6, i, size);
samples[i] = static_cast<FloatType> (0.35875 - 0.48829 * cos2 + 0.14128 * cos4 - 0.01168 * cos6);
}
}
break;
case flatTop:
{
for (size_t i = 0; i < size; ++i)
{
auto cos2 = ncos<FloatType> (2, i, size);
auto cos4 = ncos<FloatType> (4, i, size);
auto cos6 = ncos<FloatType> (6, i, size);
auto cos8 = ncos<FloatType> (8, i, size);
samples[i] = static_cast<FloatType> (1.0 - 1.93 * cos2 + 1.29 * cos4 - 0.388 * cos6 + 0.028 * cos8);
}
}
break;
case kaiser:
{
const double factor = 1.0 / SpecialFunctions::besselI0 (beta);
for (size_t i = 0; i < size; ++i)
samples[i] = static_cast<FloatType> (SpecialFunctions::besselI0 (beta * std::sqrt (1.0 - std::pow ((i - 0.5 * (size - 1.0))
/ ( 0.5 * (size - 1.0)), 2.0)))
* factor);
}
break;
default:
jassertfalse;
break;
}
// DC frequency amplitude must be one
if (normalise)
{
FloatType sum (0);
for (size_t i = 0; i < size; ++i)
sum += samples[i];
auto factor = static_cast<FloatType> (size) / sum;
FloatVectorOperations::multiply (samples, factor, static_cast<int> (size));
}
}
template <typename FloatType>
void WindowingFunction<FloatType>::multiplyWithWindowingTable (FloatType* samples, size_t size) noexcept
{
FloatVectorOperations::multiply (samples, windowTable.getRawDataPointer(), jmin (static_cast<int> (size), windowTable.size()));
}
template <typename FloatType>
const char* WindowingFunction<FloatType>::getWindowingMethodName (WindowingMethod type) noexcept
{
switch (type)
{
case rectangular: return "Rectangular";
case triangular: return "Triangular";
case hann: return "Hann";
case hamming: return "Hamming";
case blackman: return "Blackman";
case blackmanHarris: return "Blackman-Harris";
case flatTop: return "Flat Top";
case kaiser: return "Kaiser";
default: jassertfalse; return "";
}
}
template class WindowingFunction<float>;
template class WindowingFunction<double>;
} // namespace dsp
} // namespace juce
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