text: #pragma once
  
  #include <stdbool.h>
  #include <stdint.h>
  
  /* Find the dominant frequency in the FFT. 
   * Returns a *normalized* frequency, in buckets. */
  extern float peak(float *magnitudes, unsigned int count);
  
  /* Convert uint16_t samples to complex floats, windowed for FFT'ing.
   * Returns false on error. */
  extern bool window(const uint16_t *samples,
                     float *real,
                     float *imag,
                     unsigned int count);
  
  /* Convert complex numbers from cartesian to polar coordinates. */
  extern void make_polar(const float *real,
                         const float *imag,
                         float *abs,
                         float *angle,
                         unsigned int count);
  