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fastsa
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factor out FFT

master
Sebastien Bourdeauducq 2023-09-13 10:40:07 +08:00
parent 9e842ddad5
commit 52bbfc0c33
3 changed files with 29 additions and 20 deletions
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2
Makefile
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@ -1,5 +1,5 @@
EXE = fastsa
SOURCES = main.cpp
SOURCES = fft.cpp main.cpp
SOURCES += $(IMGUI_DIR)/imgui.cpp $(IMGUI_DIR)/imgui_demo.cpp $(IMGUI_DIR)/imgui_draw.cpp $(IMGUI_DIR)/imgui_tables.cpp $(IMGUI_DIR)/imgui_widgets.cpp
SOURCES += $(IMGUI_DIR)/backends/imgui_impl_glfw.cpp $(IMGUI_DIR)/backends/imgui_impl_opengl3.cpp
OBJS = $(addsuffix .o, $(basename $(notdir $(SOURCES))))

23
fft.cpp Normal file
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@ -0,0 +1,23 @@
#include <vector>
#include <complex>
#define POCKETFFT_CACHE_SIZE (16*1024*1024)
#define POCKETFFT_NO_MULTITHREADING // MT doesn't seem to help at small sizes
#include <pocketfft_hdronly.h>
void fft_mag(std::complex<float>* in, float* out, size_t len)
{
pocketfft::shape_t shape{len};
pocketfft::stride_t stride(1);
stride[0] = sizeof(std::complex<float>);
pocketfft::shape_t axes;
axes.push_back(0);
std::vector<std::complex<float>> out_rev(len);
pocketfft::c2c(shape, stride, stride, axes, pocketfft::FORWARD, in, out_rev.data(), 1.0f);
// negative frequencies first
for(size_t i=0;i<len/2;i++)
out[i] = abs(out_rev[i + len/2]);
for(size_t i=0;i<len/2;i++)
out[i + len/2] = abs(out_rev[i]);
}

24
main.cpp
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@ -18,12 +18,12 @@
#include <libbladeRF.h>
#define POCKETFFT_CACHE_SIZE (16*1024*1024)
#define POCKETFFT_NO_MULTITHREADING // MT doesn't seem to help at small sizes
#include <pocketfft_hdronly.h>
namespace net = std::experimental::net;
void fft_mag(std::complex<float>* in, float* out, size_t len);
static std::atomic<bool> terminate_dsp;
struct bladerf* bladerf_dev;
@ -51,12 +51,6 @@ static void dsp_thread() {
size_t len = 16384;
std::vector<std::complex<int16_t>> frames(len);
std::vector<std::complex<float>> frames_f(len);
pocketfft::shape_t shape{len};
pocketfft::stride_t stride(1);
stride[0] = sizeof(std::complex<float>);
pocketfft::shape_t axes;
axes.push_back(0);
std::vector<std::complex<float>> frames_ft_rev(len);
std::vector<float> frames_mag(len);
int iterations = 0;
@ -69,15 +63,7 @@ static void dsp_thread() {
break;
}
// FFT
for(size_t i=0;i<len;i++)
frames_f[i] = frames[i];
pocketfft::c2c(shape, stride, stride, axes, pocketfft::FORWARD, frames_f.data(), frames_ft_rev.data(), 1.0f);
// negative frequencies first
for(size_t i=0;i<len/2;i++)
frames_mag[i] = abs(frames_ft_rev[i + len/2]);
for(size_t i=0;i<len/2;i++)
frames_mag[i + len/2] = abs(frames_ft_rev[i]);
fft_mag(frames_f.data(), frames_mag.data(), len);
// stabilize laser
bool tick = false;