mirror of
https://github.com/bolero-MURAKAMI/Sprout.git
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82 lines
3 KiB
C++
82 lines
3 KiB
C++
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/*=============================================================================
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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_COEFFICIENT_ARRAY_HPP
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#define SPROUT_NUMERIC_FFT_COEFFICIENT_ARRAY_HPP
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#include <sprout/config.hpp>
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#include <sprout/array.hpp>
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#include <sprout/bit/bit_length.hpp>
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#include <sprout/index_tuple/make_index_tuple.hpp>
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#include <sprout/complex.hpp>
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#include <sprout/math/cos.hpp>
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#include <sprout/math/sin.hpp>
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#include <sprout/math/constants.hpp>
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namespace sprout {
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namespace detail
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{
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template<typename value_type, sprout::index_t... Indexes>
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inline SPROUT_CONSTEXPR sprout::array<sprout::complex<value_type>, sizeof...(Indexes)*2>
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make_fft_coefficients_impl(
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sprout::array<sprout::complex<value_type>, sizeof...(Indexes)> const& arr,
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sprout::complex<value_type> mul, sprout::index_tuple<Indexes...>
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)
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{
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return sprout::array<sprout::complex<value_type>, sizeof...(Indexes)*2>{ {
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arr[Indexes]..., (arr[Indexes] * mul)...
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} };
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}
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template<typename value_type, std::size_t N, std::size_t Size>
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inline SPROUT_CONSTEXPR typename std::enable_if<
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N == 0,
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typename sprout::array<sprout::complex<value_type>, 1>
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>::type
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make_fft_coefficients_loop( bool ) {
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return typename sprout::array<sprout::complex<value_type>, 1>{ {
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{ static_cast<value_type>( 1 ) }
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} };
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}
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template<typename value_type, std::size_t N, std::size_t Size>
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inline SPROUT_CONSTEXPR typename std::enable_if<
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N != 0,
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typename sprout::array<sprout::complex<value_type>, 1 << N>
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>::type
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make_fft_coefficients_loop(bool inverse)
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{
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return make_fft_coefficients_impl(
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make_fft_coefficients_loop<value_type, N - 1, Size>(inverse),
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{
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sprout::cos((inverse?-1:1)*sprout::math::two_pi<value_type>() / (1 << Size >> (N - 1))),
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sprout::sin((inverse?-1:1)*sprout::math::two_pi<value_type>() / (1 << Size >> (N - 1)))
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},
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sprout::make_index_tuple<1 << (N - 1)>()
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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>, 1 << Size>
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make_fft_coefficients(bool inverse) {
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return make_fft_coefficients_loop<value_type, Size, Size>(inverse);
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}
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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::array<sprout::complex<value_type>, Size>
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make_fft_coefficients() {
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return sprout::detail::make_fft_coefficients<value_type, sprout::bit_length(Size)-1>(false);
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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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make_ifft_coefficients() {
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return sprout::detail::make_fft_coefficients<value_type, sprout::bit_length(Size)-1>(true);
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}
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} // namespce sprout
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#endif // SPROUT_NUMERIC_FFT_COEFFICIENT_ARRAY_HPP
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