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Use std::ranges to calculate FFT window function.
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@RalphSteinhagen
slebedev authored and RalphSteinhagen committed Sep 14, 2023
1 parent 19e403b commit 39c680c
Showing 1 changed file with 47 additions and 38 deletions.
85 changes: 47 additions & 38 deletions test/blocklib/core/fft/window.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -4,6 +4,7 @@

#include <cmath>
#include <numbers>
#include <ranges>
#include <vector>

namespace gr::blocks::fft {
Expand All @@ -20,80 +21,88 @@ enum class WindowFunction : int { None, Rectangular, Hamming, Hann, HannExp, Bla
template<FloatOrDoubleType T>
std::vector<T>
createWindowFunction(WindowFunction func, const std::size_t n) {
constexpr T pi = std::numbers::pi_v<T>;
constexpr T pi2 = static_cast<T>(2.) * pi;
const T exp0 = std::exp(static_cast<T>(0.));
constexpr T c1 = 1.;
constexpr T c2 = 2.;
constexpr T c3 = 3.;
constexpr T c4 = 4.;
std::vector<T> res(n);
constexpr T pi = std::numbers::pi_v<T>;
constexpr T pi2 = static_cast<T>(2.) * pi;
constexpr T c1 = 1.;
constexpr T c2 = 2.;
constexpr T c3 = 3.;
constexpr T c4 = 4.;

switch (func) {
case WindowFunction::None: {
return {};
}
case WindowFunction::Rectangular: {
for (std::size_t i = 0; i < n; i++) res[i] = 1.;
return res;
return std::vector<T>(n, T(1.));
}
case WindowFunction::Hamming: {
const T a = pi2 / static_cast<T>(n);
for (std::size_t i = 0; i < n; i++) res[i] = static_cast<T>(0.53836) - static_cast<T>(0.46164) * std::cos(a * static_cast<T>(i));
std::vector<T> res(n);
const T a = pi2 / static_cast<T>(n);
std::ranges::transform(std::views::iota(std::size_t(0), n), std::ranges::begin(res), [a](const auto i) { return T(0.53836) - T(0.46164) * std::cos(a * static_cast<T>(i)); });
return res;
}
case WindowFunction::Hann: {
const T a = pi2 / static_cast<T>(n - 1);
for (std::size_t i = 0; i < n; i++) res[i] = static_cast<T>(0.5) - static_cast<T>(0.5) * std::cos(a * static_cast<T>(i));
std::vector<T> res(n);
const T a = pi2 / static_cast<T>(n - 1);
std::ranges::transform(std::views::iota(std::size_t(0), n), std::ranges::begin(res), [a](const auto i) { return T(0.5) - T(0.5) * std::cos(a * static_cast<T>(i)); });
return res;
}
case WindowFunction::HannExp: {
const T a = pi2 / static_cast<T>(n - 1);
for (std::size_t i = 0; i < n; i++) res[i] = std::pow(std::sin(a * static_cast<T>(i)), c2);
std::vector<T> res(n);
const T a = pi2 / static_cast<T>(n - 1);
std::ranges::transform(std::views::iota(std::size_t(0), n), std::ranges::begin(res), [a](const auto i) { return std::pow(std::sin(a * static_cast<T>(i)), c2); });
return res;
}
case WindowFunction::Blackman: {
const T a = pi2 / static_cast<T>(n - 1);
for (std::size_t i = 0; i < n; i++) {
std::vector<T> res(n);
const T a = pi2 / static_cast<T>(n - 1);
std::ranges::transform(std::views::iota(std::size_t(0), n), std::ranges::begin(res), [a](const auto i) {
const T ai = a * static_cast<T>(i);
res[i] = static_cast<T>(0.42) - static_cast<T>(0.5) * std::cos(ai) + static_cast<T>(0.08) * std::cos(c2 * ai);
}
return T(0.42) - T(0.5) * std::cos(ai) + T(0.08) * std::cos(c2 * ai);
});
return res;
}
case WindowFunction::Nuttall: {
const T a = pi2 / static_cast<T>(n - 1);
for (std::size_t i = 0; i < n; i++) {
std::vector<T> res(n);
const T a = pi2 / static_cast<T>(n - 1);
std::ranges::transform(std::views::iota(std::size_t(0), n), std::ranges::begin(res), [a](const auto i) {
const T ai = a * static_cast<T>(i);
res[i] = static_cast<T>(0.355768) - static_cast<T>(0.487396) * std::cos(ai) + static_cast<T>(0.144232) * std::cos(c2 * ai) - static_cast<T>(0.012604) * std::cos(c3 * ai);
}
return T(0.355768) - T(0.487396) * std::cos(ai) + T(0.144232) * std::cos(c2 * ai) - T(0.012604) * std::cos(c3 * ai);
});
return res;
}
case WindowFunction::BlackmanHarris: {
const T a = pi2 / static_cast<T>(n - 1);
for (std::size_t i = 0; i < n; i++) {
std::vector<T> res(n);
const T a = pi2 / static_cast<T>(n - 1);
std::ranges::transform(std::views::iota(std::size_t(0), n), std::ranges::begin(res), [a](const auto i) {
const T ai = a * static_cast<T>(i);
res[i] = static_cast<T>(0.35875) - static_cast<T>(0.48829) * std::cos(ai) + static_cast<T>(0.14128) * std::cos(c2 * ai) - static_cast<T>(0.01168) * std::cos(c3 * ai);
}
return T(0.35875) - T(0.48829) * std::cos(ai) + T(0.14128) * std::cos(c2 * ai) - T(0.01168) * std::cos(c3 * ai);
});
return res;
}
case WindowFunction::BlackmanNuttall: {
const T a = pi2 / static_cast<T>(n - 1);
for (std::size_t i = 0; i < n; i++) {
std::vector<T> res(n);
const T a = pi2 / static_cast<T>(n - 1);
std::ranges::transform(std::views::iota(std::size_t(0), n), std::ranges::begin(res), [a](const auto i) {
const T ai = a * static_cast<T>(i);
res[i] = static_cast<T>(0.3635819) - static_cast<T>(0.4891775) * std::cos(ai) + static_cast<T>(0.1365995) * std::cos(c2 * ai) - static_cast<T>(0.0106411) * std::cos(c3 * ai);
}
return T(0.3635819) - T(0.4891775) * std::cos(ai) + T(0.1365995) * std::cos(c2 * ai) - T(0.0106411) * std::cos(c3 * ai);
});
return res;
}
case WindowFunction::FlatTop: {
const T a = pi2 / static_cast<T>(n - 1);
for (std::size_t i = 0; i < n; i++) {
std::vector<T> res(n);
const T a = pi2 / static_cast<T>(n - 1);
std::ranges::transform(std::views::iota(std::size_t(0), n), std::ranges::begin(res), [a](const auto i) {
const T ai = a * static_cast<T>(i);
res[i] = c1 - static_cast<T>(1.93) * std::cos(ai) + static_cast<T>(1.29) * std::cos(c2 * ai) - static_cast<T>(0.388) * std::cos(c3 * ai) + static_cast<T>(0.032) * std::cos(c4 * ai);
}
return c1 - T(1.93) * std::cos(ai) + T(1.29) * std::cos(c2 * ai) - T(0.388) * std::cos(c3 * ai) + T(0.032) * std::cos(c4 * ai);
});
return res;
}
case WindowFunction::Exponential: {
const T a = c3 * static_cast<T>(n);
for (std::size_t i = 0; i < n; i++) res[i] = std::exp(static_cast<T>(i) / a) / exp0;
std::vector<T> res(n);
const T exp0 = std::exp(T(0.));
const T a = c3 * static_cast<T>(n);
std::ranges::transform(std::views::iota(std::size_t(0), n), std::ranges::begin(res), [a, exp0](const auto i) { return std::exp(static_cast<T>(i) / a) / exp0; });
return res;
}
default: {
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