mirror of
https://github.com/bolero-MURAKAMI/Sprout.git
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118 lines
5.1 KiB
C++
118 lines
5.1 KiB
C++
/*=============================================================================
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Copyright (c) 2011-2016 Bolero MURAKAMI
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https://github.com/bolero-MURAKAMI/Sprout
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Distributed under the Boost Software License, Version 1.0. (See accompanying
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file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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=============================================================================*/
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#ifndef SPROUT_NUMERIC_FFT_FIXED_FFT_HPP
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#define SPROUT_NUMERIC_FFT_FIXED_FFT_HPP
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#include <sprout/config.hpp>
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#include <sprout/array.hpp>
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#include <sprout/index_tuple/make_index_tuple.hpp>
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#include <sprout/algorithm/fixed/results.hpp>
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#include <sprout/complex.hpp>
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#include <sprout/math/less.hpp>
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#include <sprout/pit/pit.hpp>
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#include <sprout/numeric/fft/coefficients.hpp>
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namespace sprout {
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namespace fixed {
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namespace detail {
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template<typename value_type, std::size_t Size>
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inline SPROUT_CONSTEXPR sprout::complex<value_type>
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fft_element(
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sprout::array<sprout::complex<value_type>, Size> const& arr,
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std::size_t step, std::size_t i, std::size_t j, bool sub,
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sprout::array<sprout::complex<value_type>, Size> const& coeffs
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)
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{
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return sub
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? arr[i * step + j] - coeffs[j * (Size / 2 / step)] * arr[i * step + j + Size / 2]
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: arr[i * step + j] + coeffs[j * (Size / 2 / step)] * arr[i * step + j + Size / 2]
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;
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}
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template<typename value_type, std::size_t Size, sprout::index_t... Indexes>
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inline SPROUT_CONSTEXPR sprout::array<sprout::complex<value_type>, Size>
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butterfly(
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sprout::array<sprout::complex<value_type>, Size> const& arr,
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std::size_t step,
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sprout::array<sprout::complex<value_type>, Size> const& coeffs,
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sprout::index_tuple<Indexes...>
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)
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{
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return sprout::array<sprout::complex<value_type>, Size> { {
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fft_element(arr, step, Indexes / (step * 2), Indexes%step, (Indexes&step) != 0, coeffs)...
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} };
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}
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template<typename value_type, std::size_t Size>
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inline SPROUT_CONSTEXPR sprout::array<sprout::complex<value_type>, Size>
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fft_loop(
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sprout::array<sprout::complex<value_type>, Size> const& arr,
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std::size_t step,
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sprout::array<sprout::complex<value_type>, Size> const& coeffs
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)
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{
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return step == Size ? arr
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: fft_loop(butterfly(arr, step, coeffs, sprout::make_index_tuple<Size>()), step * 2, coeffs);
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}
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template<typename value_type, std::size_t Size>
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inline SPROUT_CONSTEXPR sprout::array<sprout::complex<value_type>, Size>
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fft(sprout::array<sprout::complex<value_type>, Size> const& arr) {
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return fft_loop(arr, 1, sprout::make_fft_coefficients<value_type, Size>());
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}
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template<typename Container, sprout::index_t... Indexes>
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inline SPROUT_CONSTEXPR sprout::array<typename sprout::container_traits<Container>::value_type, sizeof...(Indexes)>
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make_input_impl(Container const& cont, sprout::index_tuple<Indexes...>) {
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return sprout::array<typename sprout::container_traits<Container>::value_type, sizeof...(Indexes)> { {
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(sprout::math::less(Indexes, cont.size())
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? *sprout::next(sprout::begin(cont), Indexes)
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: static_cast<typename sprout::container_traits<Container>::value_type>(0)
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)...
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} };
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}
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template<std::size_t Size, typename Container>
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inline SPROUT_CONSTEXPR sprout::array<typename sprout::container_traits<Container>::value_type, Size>
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make_input(Container const& cont) {
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return make_input_impl(cont, sprout::make_index_tuple<Size>());
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}
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template<typename value_type, std::size_t Size, typename Result, sprout::index_t... Indexes>
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inline SPROUT_CONSTEXPR typename sprout::fixed::results::algorithm<Result>::type
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make_fft_result_impl(sprout::array<sprout::complex<value_type>, Size> const& cont, Result const& result, sprout::index_tuple<Indexes...>) {
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return remake<Result>(result, sprout::size(result), cont[Indexes]...);
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}
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template<typename value_type, std::size_t Size, typename Result>
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inline SPROUT_CONSTEXPR typename sprout::fixed::results::algorithm<Result>::type
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make_fft_result(sprout::array<sprout::complex<value_type>, Size> const& cont, Result const& result) {
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return make_fft_result_impl(cont, result, sprout::make_index_tuple<sprout::container_traits<Result>::static_size>());
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}
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} // namespace detail
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//
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// fft
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// Algorithm: Stockham decimation-in-time
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//
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template<typename Container, typename Result>
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inline SPROUT_CONSTEXPR typename sprout::fixed::results::algorithm<Result>::type
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fft(Container const& cont, Result const& result) {
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return sprout::fixed::detail::make_fft_result(
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sprout::fixed::detail::fft(sprout::fixed::detail::make_input<sprout::container_traits<Result>::static_size>(cont)), result
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);
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}
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template<typename Result, typename Container>
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inline SPROUT_CONSTEXPR typename sprout::fixed::results::algorithm<Result>::type
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fft(Container const& cont) {
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return sprout::fixed::fft(cont, sprout::pit<Result>());
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}
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} // namespace fixed
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using sprout::fixed::fft;
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} // namespace sprout
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#endif // #ifndef SPROUT_NUMERIC_FFT_FIXED_FFT_HPP
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