diff options
| author | Christoph Mayer <hcab14@gmail.com> | 2019-05-23 10:58:51 +0000 |
|---|---|---|
| committer | Martin Braun <martin.braun@ettus.com> | 2019-06-15 17:17:02 -0700 |
| commit | 6996d1b7ee20fb7611068906bb64886eb5b514ef (patch) | |
| tree | d121f1ba55aaea456906aca4f46c66b0be83bf6e /gr-fft | |
| parent | 565d133ff028b316a9d920e631df0bd38cd7bd1e (diff) | |
fft: Add fft_shift class
This is a generic FFT shift object. Includes C++ unit tests.
The class is templated and thus works with FFTs of any type.
Diffstat (limited to 'gr-fft')
| -rw-r--r-- | gr-fft/include/gnuradio/fft/CMakeLists.txt | 1 | ||||
| -rw-r--r-- | gr-fft/include/gnuradio/fft/fft_shift.h | 82 | ||||
| -rw-r--r-- | gr-fft/lib/CMakeLists.txt | 15 | ||||
| -rw-r--r-- | gr-fft/lib/qa_fft_shift.cc | 62 |
4 files changed, 160 insertions, 0 deletions
diff --git a/gr-fft/include/gnuradio/fft/CMakeLists.txt b/gr-fft/include/gnuradio/fft/CMakeLists.txt index 0f52b0aa96..2bd77b8d3c 100644 --- a/gr-fft/include/gnuradio/fft/CMakeLists.txt +++ b/gr-fft/include/gnuradio/fft/CMakeLists.txt @@ -23,6 +23,7 @@ install(FILES api.h fft.h + fft_shift.h fft_vcc.h fft_vfc.h goertzel.h diff --git a/gr-fft/include/gnuradio/fft/fft_shift.h b/gr-fft/include/gnuradio/fft/fft_shift.h new file mode 100644 index 0000000000..1ee08915b9 --- /dev/null +++ b/gr-fft/include/gnuradio/fft/fft_shift.h @@ -0,0 +1,82 @@ +/* -*- c++ -*- */ +/* + * Copyright 2019 Free Software Foundation, Inc. + * + * This file is part of GNU Radio + * + * GNU Radio is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 3, or (at your option) + * any later version. + * + * GNU Radio is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with GNU Radio; see the file COPYING. If not, write to + * the Free Software Foundation, Inc., 51 Franklin Street, + * Boston, MA 02110-1301, USA. + */ + +#ifndef INCLUDED_FFT_FFT_SHIFT_H +#define INCLUDED_FFT_FFT_SHIFT_H + +#include <algorithm> +#include <cassert> +#include <vector> + +namespace gr { +namespace fft { + + /*! \brief reorder FFT results which are ordered from 0 to 1 in normalized frequency + * to -0.5 to 0.5 by cyclic shift + */ + template<typename T> + class fft_shift { + public: + fft_shift(size_t fft_length) + : d_fftlen(fft_length) + , d_lenpos(fft_length/2 + (fft_length%2)) + , d_lenneg(fft_length/2) + , d_buf(fft_length) {} + + /*! performs the cyclic shift on a vector v + */ + void shift(std::vector<T>& v) { + shift(&v.front(), v.size()); + } + + /*! performs the cyclic shift on an array + */ + void shift(T* data, size_t fft_len) { + resize(fft_len); + std::copy_n(data, d_lenpos, d_buf.begin()); + std::copy_n(data+d_lenpos, d_lenneg, data); + std::copy_n(d_buf.begin(), d_lenpos, data+d_lenneg); + } + + /*! if needed adjusts the buffer size to a new fft length + */ + void resize(size_t fft_length) { + if (d_fftlen == fft_length) + return; + d_fftlen = fft_length; + d_lenpos = d_fftlen/2 + (d_fftlen%2); + d_lenneg = d_fftlen/2; + assert(d_lenpos + d_lenneg == d_fftlen); + d_buf.resize(d_lenpos); + } + protected: + + private: + size_t d_fftlen; // FFT length + size_t d_lenpos; // number of FFT bins with positive frequencies + size_t d_lenneg; // number of FFT bins with negative frequencies + std::vector<T> d_buf; // buffer used for cyclic shift + } ; + +} // namespace fft +} // namespace gr +#endif // INCLUDED_FFT_FFT_SHIFT_H diff --git a/gr-fft/lib/CMakeLists.txt b/gr-fft/lib/CMakeLists.txt index 7b8207665e..14541fcffc 100644 --- a/gr-fft/lib/CMakeLists.txt +++ b/gr-fft/lib/CMakeLists.txt @@ -65,3 +65,18 @@ endif(MSVC) if(BUILD_SHARED_LIBS) GR_LIBRARY_FOO(gnuradio-fft FFTW3f) endif() + +if(ENABLE_TESTING) + include(GrTest) + + list(APPEND test_gr_fft_sources + qa_fft_shift + ) + list(APPEND GR_TEST_TARGET_DEPS gnuradio-fft) + + foreach(qa_file ${test_gr_fft_sources}) + GR_ADD_CPP_TEST("fft_${qa_file}" + ${CMAKE_CURRENT_SOURCE_DIR}/${qa_file} + ) + endforeach(qa_file) +endif(ENABLE_TESTING) diff --git a/gr-fft/lib/qa_fft_shift.cc b/gr-fft/lib/qa_fft_shift.cc new file mode 100644 index 0000000000..e924af8629 --- /dev/null +++ b/gr-fft/lib/qa_fft_shift.cc @@ -0,0 +1,62 @@ +/* -*- c++ -*- */ +/* + * Copyright 2019 Free Software Foundation, Inc. + * + * This file is part of GNU Radio + * + * GNU Radio is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 3, or (at your option) + * any later version. + * + * GNU Radio is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with GNU Radio; see the file COPYING. If not, write to + * the Free Software Foundation, Inc., 51 Franklin Street, + * Boston, MA 02110-1301, USA. + */ + +#ifdef HAVE_CONFIG_H +#include <config.h> +#endif + +#include <gnuradio/fft/fft_shift.h> +#include <boost/test/unit_test.hpp> +#include <vector> + +namespace gr { +namespace fft { + +BOOST_AUTO_TEST_CASE(t1) +{ + fft::fft_shift<int> s(1023); + + std::vector<int> x_even{ 0, 1, 2, 3, -4, -3, -2, -1 }; + std::vector<int> y_even{ -4, -3, -2, -1, 0, 1, 2, 3 }; // expected result + + s.shift(x_even); + BOOST_TEST(x_even == y_even, boost::test_tools::per_element()); + + // two shifts should not change the result + s.shift(x_even); + s.shift(x_even); + BOOST_TEST(x_even == y_even, boost::test_tools::per_element()); +} + +BOOST_AUTO_TEST_CASE(t2) +{ + fft::fft_shift<int> s(7); + + std::vector<int> x_odd{ 0, 1, 2, 3, -3, -2, -1 }; + std::vector<int> y_odd{ -3, -2, -1, 0, 1, 2, 3 }; // expected result + + s.shift(x_odd); + BOOST_TEST(x_odd == y_odd, boost::test_tools::per_element()); +} + +} /* namespace fft */ +} /* namespace gr */ |