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/*
==============================================================================
This file is part of the JUCE framework.
Copyright (c) Raw Material Software Limited
JUCE is an open source framework subject to commercial or open source
licensing.
By downloading, installing, or using the JUCE framework, or combining the
JUCE framework with any other source code, object code, content or any other
copyrightable work, you agree to the terms of the JUCE End User Licence
Agreement, and all incorporated terms including the JUCE Privacy Policy and
the JUCE Website Terms of Service, as applicable, which will bind you. If you
do not agree to the terms of these agreements, we will not license the JUCE
framework to you, and you must discontinue the installation or download
process and cease use of the JUCE framework.
JUCE End User Licence Agreement: https://juce.com/legal/juce-8-licence/
JUCE Privacy Policy: https://juce.com/juce-privacy-policy
JUCE Website Terms of Service: https://juce.com/juce-website-terms-of-service/
Or:
You may also use this code under the terms of the AGPLv3:
https://www.gnu.org/licenses/agpl-3.0.en.html
THE JUCE FRAMEWORK IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL
WARRANTIES, WHETHER EXPRESSED OR IMPLIED, INCLUDING WARRANTY OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, ARE DISCLAIMED.
==============================================================================
*/
namespace juce::dsp
{
template <typename FloatType>
static 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);
const auto doubleSize = (double) size;
for (size_t i = 0; i < size; ++i)
samples[i] = static_cast<FloatType> (SpecialFunctions::besselI0 (beta * std::sqrt (1.0 - std::pow (((double) i - 0.5 * (doubleSize - 1.0))
/ ( 0.5 * (doubleSize - 1.0)), 2.0)))
* factor);
}
break;
case numWindowingMethods:
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) const 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";
case numWindowingMethods:
default: jassertfalse; return "";
}
}
template class WindowingFunction<float>;
template class WindowingFunction<double>;
} // namespace juce::dsp
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