const const const

adding hints for the compiler for optimization.
In case your custom build complains about "const", just remove the keyword. based on e82f38e277, but going further :-)

* "const" class functions : function does not modify any class attributes ( --> "this" becomes const)

* __attribute__((pure)) :  function return value depends only on the parameters and/or global variables. The function does not modify any global or static variables.
* __attribute__((const)) : function only examines arguments (no globals), and has no effects except the return value. This slightly more strict than "pure"
* hot: tells the compiler "this functions is called very often"
* cold: the opposite of hot

usermods/audioreactive/audio_reactive.h

@@ -285,7 +285,7 @@ static volatile float    micReal_max2 = 0.0f;             // MicIn data max afte
 // some prototypes, to ensure consistent interfaces
 static float mapf(float x, float in_min, float in_max, float out_min, float out_max); // map function for float
 static float fftAddAvg(int from, int to);   // average of several FFT result bins
-void FFTcode(void * parameter);      // audio processing task: read samples, run FFT, fill GEQ channels from FFT results
+void FFTcode(void * parameter)  __attribute__((noreturn));      // audio processing task: read samples, run FFT, fill GEQ channels from FFT results
 static void runMicFilter(uint16_t numSamples, float *sampleBuffer);          // pre-filtering of raw samples (band-pass)
 static void postProcessFFTResults(bool noiseGateOpen, int numberOfChannels, bool i2sFastpath); // post-processing and post-amp of GEQ channels