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AP_HAL_SITL: make harmonics part of DSP 

add vector mean function to dsp
allow fft_start() to use ObjectBuffer<float> for lock-free access
This commit is contained in:
Andy Piper 2020-03-05 21:54:00 +00:00 committed by Andrew Tridgell
parent e2ef0bd36e
commit ee87ef7013
2 changed files with 36 additions and 25 deletions
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44
libraries/AP_HAL_SITL/DSP.cpp
View File

@ -22,6 +22,7 @@
#include <GCS_MAVLink/GCS.h>
#include "DSP.h"
#include <cmath>
#include <assert.h>
using namespace HALSITL;
@ -34,10 +35,10 @@ extern const AP_HAL::HAL& hal;
// important as frequency resolution. Referred to as [Heinz] throughout the code.
// initialize the FFT state machine
AP_HAL::DSP::FFTWindowState* DSP::fft_init(uint16_t window_size, uint16_t sample_rate)
AP_HAL::DSP::FFTWindowState* DSP::fft_init(uint16_t window_size, uint16_t sample_rate, uint8_t harmonics)
{
DSP::FFTWindowStateSITL* fft = new DSP::FFTWindowStateSITL(window_size, sample_rate);
if (fft->_hanning_window == nullptr || fft->_rfft_data == nullptr || fft->_freq_bins == nullptr) {
DSP::FFTWindowStateSITL* fft = new DSP::FFTWindowStateSITL(window_size, sample_rate, harmonics);
if (fft == nullptr || fft->_hanning_window == nullptr || fft->_rfft_data == nullptr || fft->_freq_bins == nullptr || fft->_derivative_freq_bins == nullptr) {
delete fft;
return nullptr;
}
@ -45,26 +46,26 @@ AP_HAL::DSP::FFTWindowState* DSP::fft_init(uint16_t window_size, uint16_t sample
}
// start an FFT analysis
void DSP::fft_start(AP_HAL::DSP::FFTWindowState* state, const float* samples, uint16_t buffer_index, uint16_t buffer_size)
void DSP::fft_start(AP_HAL::DSP::FFTWindowState* state, FloatBuffer& samples, uint16_t advance)
{
step_hanning((FFTWindowStateSITL*)state, samples, buffer_index, buffer_size);
step_hanning((FFTWindowStateSITL*)state, samples, advance);
}
// perform remaining steps of an FFT analysis
uint16_t DSP::fft_analyse(AP_HAL::DSP::FFTWindowState* state, uint16_t start_bin, uint16_t end_bin, uint8_t harmonics, float noise_att_cutoff)
uint16_t DSP::fft_analyse(AP_HAL::DSP::FFTWindowState* state, uint16_t start_bin, uint16_t end_bin, float noise_att_cutoff)
{
FFTWindowStateSITL* fft = (FFTWindowStateSITL*)state;
step_fft(fft);
step_cmplx_mag(fft, start_bin, end_bin, harmonics, noise_att_cutoff);
step_cmplx_mag(fft, start_bin, end_bin, noise_att_cutoff);
return step_calc_frequencies(fft, start_bin, end_bin);
}
// create an instance of the FFT state machine
DSP::FFTWindowStateSITL::FFTWindowStateSITL(uint16_t window_size, uint16_t sample_rate)
: AP_HAL::DSP::FFTWindowState::FFTWindowState(window_size, sample_rate)
DSP::FFTWindowStateSITL::FFTWindowStateSITL(uint16_t window_size, uint16_t sample_rate, uint8_t harmonics)
: AP_HAL::DSP::FFTWindowState::FFTWindowState(window_size, sample_rate, harmonics)
{
if (_freq_bins == nullptr || _hanning_window == nullptr || _rfft_data == nullptr) {
gcs().send_text(MAV_SEVERITY_WARNING, "Failed to allocate window for DSP");
if (_freq_bins == nullptr || _hanning_window == nullptr || _rfft_data == nullptr || _derivative_freq_bins == nullptr) {
GCS_SEND_TEXT(MAV_SEVERITY_WARNING, "Failed to allocate window for DSP");
return;
}
@ -77,16 +78,15 @@ DSP::FFTWindowStateSITL::~FFTWindowStateSITL()
}
// step 1: filter the incoming samples through a Hanning window
void DSP::step_hanning(FFTWindowStateSITL* fft, const float* samples, uint16_t buffer_index, uint16_t buffer_size)
void DSP::step_hanning(FFTWindowStateSITL* fft, FloatBuffer& samples, uint16_t advance)
{
// 5us
// apply hanning window to gyro samples and store result in _freq_bins
// hanning starts and ends with 0, could be skipped for minor speed improvement
const uint16_t ring_buf_idx = MIN(buffer_size - buffer_index, fft->_window_size);
mult_f32(&samples[buffer_index], &fft->_hanning_window[0], &fft->_freq_bins[0], ring_buf_idx);
if (buffer_index > 0) {
mult_f32(&samples[0], &fft->_hanning_window[ring_buf_idx], &fft->_freq_bins[ring_buf_idx], fft->_window_size - ring_buf_idx);
}
uint32_t read_window = samples.peek(&fft->_freq_bins[0], fft->_window_size);
assert(read_window == fft->_window_size);
samples.advance(advance);
mult_f32(&fft->_freq_bins[0], &fft->_hanning_window[0], &fft->_freq_bins[0], fft->_window_size);
}
// step 2: performm an in-place FFT on the windowed data
@ -135,6 +135,16 @@ void DSP::vector_scale_float(const float* vin, float scale, float* vout, uint16_
}
}
float DSP::vector_mean_float(const float* vin, uint16_t len) const
{
float mean_value = 0.0f;
for (uint16_t i = 0; i < len; i++) {
mean_value += vin[i];
}
mean_value /= len;
return mean_value;
}
// simple integer log2
static uint16_t fft_log2(uint16_t n)
{

17
libraries/AP_HAL_SITL/DSP.h
View File

@ -27,29 +27,30 @@ typedef std::complex<float> complexf;
class HALSITL::DSP : public AP_HAL::DSP {
public:
// initialise an FFT instance
virtual FFTWindowState* fft_init(uint16_t window_size, uint16_t sample_rate) override;
// start an FFT analysis
virtual void fft_start(FFTWindowState* state, const float* samples, uint16_t buffer_index, uint16_t buffer_size) override;
virtual FFTWindowState* fft_init(uint16_t window_size, uint16_t sample_rate, uint8_t harmonics) override;
// start an FFT analysis with an ObjectBuffer
virtual void fft_start(FFTWindowState* state, FloatBuffer& samples, uint16_t advance) override;
// perform remaining steps of an FFT analysis
virtual uint16_t fft_analyse(FFTWindowState* state, uint16_t start_bin, uint16_t end_bin, uint8_t harmonics, float noise_att_cutoff) override;
virtual uint16_t fft_analyse(FFTWindowState* state, uint16_t start_bin, uint16_t end_bin, float noise_att_cutoff) override;
// STM32-based FFT state
class FFTWindowStateSITL : public AP_HAL::DSP::FFTWindowState {
friend class HALSITL::DSP;
protected:
FFTWindowStateSITL(uint16_t window_size, uint16_t sample_rate);
~FFTWindowStateSITL();
public:
FFTWindowStateSITL(uint16_t window_size, uint16_t sample_rate, uint8_t harmonics);
virtual ~FFTWindowStateSITL();
private:
complexf* buf;
};
private:
void step_hanning(FFTWindowStateSITL* fft, const float* samples, uint16_t buffer_index, uint16_t buffer_size);
void step_hanning(FFTWindowStateSITL* fft, FloatBuffer& samples, uint16_t advance);
void step_fft(FFTWindowStateSITL* fft);
void mult_f32(const float* v1, const float* v2, float* vout, uint16_t len);
void vector_max_float(const float* vin, uint16_t len, float* maxValue, uint16_t* maxIndex) const override;
void vector_scale_float(const float* vin, float scale, float* vout, uint16_t len) const override;
float vector_mean_float(const float* vin, uint16_t len) const override;
void calculate_fft(complexf* f, uint16_t length);
};