mirror of https://github.com/ArduPilot/ardupilot
92 lines
3.3 KiB
C
92 lines
3.3 KiB
C
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/*
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* This file is free software: you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the
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* Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This file is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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* See the GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program. If not, see <http://www.gnu.org/licenses/>.
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*
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* Code by Andy Piper and the betaflight team
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*/
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#pragma once
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#include <AP_HAL/AP_HAL.h>
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#include "AP_HAL_ChibiOS_Namespace.h"
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#if HAL_WITH_DSP
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#include <arm_math.h>
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#define DEBUG_FFT 0
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// ChibiOS implementation of FFT analysis to run on STM32 processors
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class ChibiOS::DSP : public AP_HAL::DSP {
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public:
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// initialise an FFT instance
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virtual FFTWindowState* fft_init(uint16_t window_size, uint16_t sample_rate) override;
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// start an FFT analysis
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virtual void fft_start(FFTWindowState* state, const float* samples, uint16_t buffer_index, uint16_t buffer_size) override;
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// perform remaining steps of an FFT analysis
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virtual uint16_t fft_analyse(FFTWindowState* state, uint16_t start_bin, uint16_t end_bin, uint8_t harmonics, float noise_att_cutoff) override;
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// STM32-based FFT state
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class FFTWindowStateARM : public AP_HAL::DSP::FFTWindowState {
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friend class ChibiOS::DSP;
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protected:
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FFTWindowStateARM(uint16_t window_size, uint16_t sample_rate);
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~FFTWindowStateARM();
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private:
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// underlying CMSIS data structure for FFT analysis
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arm_rfft_fast_instance_f32 _fft_instance;
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};
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protected:
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void vector_max_float(const float* vin, uint16_t len, float* maxValue, uint16_t* maxIndex) const override {
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uint32_t mindex;
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arm_max_f32(vin, len, maxValue, &mindex);
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*maxIndex = mindex;
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}
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void vector_scale_float(const float* vin, float scale, float* vout, uint16_t len) const override {
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arm_scale_f32(vin, scale, vout, len);
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}
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private:
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// following are the six independent steps for calculating an FFT
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void step_hanning(FFTWindowStateARM* fft, const float* samples, uint16_t buffer_index, uint16_t buffer_size);
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void step_arm_cfft_f32(FFTWindowStateARM* fft);
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void step_bitreversal(FFTWindowStateARM* fft);
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void step_stage_rfft_f32(FFTWindowStateARM* fft);
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void step_arm_cmplx_mag_f32(FFTWindowStateARM* fft, uint16_t start_bin, uint16_t end_bin, uint8_t harmonics, float noise_att_cutoff);
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uint16_t step_calc_frequencies_f32(FFTWindowStateARM* fft, uint16_t start_bin, uint16_t end_bin);
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// candan's frequency interpolator
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float calculate_candans_estimator(const FFTWindowStateARM* fft, uint16_t k) const;
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#if DEBUG_FFT
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class StepTimer {
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public:
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uint32_t _timer_total;
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uint32_t _timer_avg;
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uint8_t _time_ticks;
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void time(uint32_t start);
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};
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uint32_t _output_count;
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StepTimer _hanning_timer;
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StepTimer _arm_cfft_f32_timer;
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StepTimer _bitreversal_timer;
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StepTimer _stage_rfft_f32_timer;
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StepTimer _arm_cmplx_mag_f32_timer;
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StepTimer _step_calc_frequencies;
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#endif
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};
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#endif
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