Add fft

src/fft.h

@@ -0,0 +1,12 @@
+#pragma once
+#include <stdlib.h>
+#include <math.h>
+
+
+#ifndef M_PI
+#define M_PI 3.14159265358979323846
+#endif
+
+#define FFT_SIZE 4096
+void init_hamming_window();
+void compute_fft(float* time_data, float* freq_out);