DUE's more advanced FFT capabilities

Hardware Arduino Due
13

How can I implement this code to do an FFT from an AnalogRead

I attempted to ad the following code in place of the specified test signal "float32_t testInput_f32_10khz[2048]"

for (int x=0;x<2048;x++){
   float32_t voltage = analogRead(A0) * (5 / 1023.0);
   testInput_f32_10khz[x]=voltage;
   x++;
   testInput_f32_10khz[x]=0.000000000000000;
  }

But it always replies with a 0 value for the testIndex