DIY Music Relative RGB Strip light

#include <FastLED.h>

/** BASIC CONFIGURATION  **/

//The amount of LEDs in the setup
#define NUM_LEDS 60
//The pin that controls the LEDs
#define LED_PIN 6
//The pin that we read sensor values form
#define ANALOG_READ 0

//Confirmed microphone low value, and max value
#define MIC_LOW 0.0
#define MIC_HIGH 737.0
/** Other macros */
//How many previous sensor values effects the operating average?
#define AVGLEN 5
//How many previous sensor values decides if we are on a peak/HIGH (e.g. in a song)
#define LONG_SECTOR 50

//Mneumonics
#define HIGH 3
#define NORMAL 2

//How long do we keep the "current average" sound, before restarting the measuring
#define MSECS 30 * 1000
#define CYCLES MSECS / DELAY

/*Sometimes readings are wrong or strange. How much is a reading allowed
to deviate from the average to not be discarded? **/
#define DEV_THRESH 0.8

//Arduino loop delay
#define DELAY 1

float fscale( float originalMin, float originalMax, float newBegin, float newEnd, float inputValue, float curve);
void insert(int val, int *avgs, int len);
int compute_average(int *avgs, int len);
void visualize_music();

//How many LEDs to we display
int curshow = NUM_LEDS;

/*Not really used yet. Thought to be able to switch between sound reactive
mode, and general gradient pulsing/static color*/
int mode = 0;

//Showing different colors based on the mode.
int songmode = NORMAL;

//Average sound measurement the last CYCLES
unsigned long song_avg;

//The amount of iterations since the song_avg was reset
int iter = 0;

//The speed the LEDs fade to black if not relit
float fade_scale = 1.2;

//Led array
CRGB leds[NUM_LEDS];

/*Short sound avg used to "normalize" the input values.
We use the short average instead of using the sensor input directly */
int avgs[AVGLEN] = {-1};

//Longer sound avg
int long_avg[LONG_SECTOR] = {-1};

//Keeping track how often, and how long times we hit a certain mode
struct time_keeping {
  unsigned long times_start;
  short times;
};

//How much to increment or decrement each color every cycle
struct color {
  int r;
  int g;
  int b;
};

struct time_keeping high;
struct color Color; 

void setup() {
  Serial.begin(9600);
  //Set all lights to make sure all are working as expected
  FastLED.addLeds<NEOPIXEL, LED_PIN>(leds, NUM_LEDS);
  for (int i = 0; i < NUM_LEDS; i++) 
    leds[i] = CRGB(0, 0, 255);
  FastLED.show(); 
  delay(1000);  

  //bootstrap average with some low values
  for (int i = 0; i < AVGLEN; i++) {  
    insert(250, avgs, AVGLEN);
  }

  //Initial values
  high.times = 0;
  high.times_start = millis();
  Color.r = 0;  
  Color.g = 0;
  Color.b = 1;
}

/*With this we can change the mode if we want to implement a general 
lamp feature, with for instance general pulsing. Maybe if the
sound is low for a while? */
void loop() {
  switch(mode) {
    case 0:
      visualize_music();
      break;
    default:
      break;
  }
    delay(DELAY);       // delay in between reads for stability
}


/**Funtion to check if the lamp should either enter a HIGH mode,
or revert to NORMAL if already in HIGH. If the sensors report values
that are higher than 1.1 times the average values, and this has happened
more than 30 times the last few milliseconds, it will enter HIGH mode. 
TODO: Not very well written, remove hardcoded values, and make it more
reusable and configurable.  */
void check_high(int avg) {
  if (avg > (song_avg/iter * 1.1))  {
    if (high.times != 0) {
      if (millis() - high.times_start > 200.0) {
        high.times = 0;
        songmode = NORMAL;
      } else {
        high.times_start = millis();  
        high.times++; 
      }
    } else {
      high.times++;
      high.times_start = millis();

    }
  }
  if (high.times > 30 && millis() - high.times_start < 50.0)
    songmode = HIGH;
  else if (millis() - high.times_start > 200) {
    high.times = 0;
    songmode = NORMAL;
  }
}

//Main function for visualizing the sounds in the lamp
void visualize_music() {
  int sensor_value, mapped, avg, longavg;
  
  //Actual sensor value
  sensor_value = analogRead(ANALOG_READ);
  
  //If 0, discard immediately. Probably not right and save CPU.
  if (sensor_value == 0)
    return;

  //Discard readings that deviates too much from the past avg.
  mapped = (float)fscale(MIC_LOW, MIC_HIGH, MIC_LOW, (float)MIC_HIGH, (float)sensor_value, 2.0);
  avg = compute_average(avgs, AVGLEN);

  if (((avg - mapped) > avg*DEV_THRESH)) //|| ((avg - mapped) < -avg*DEV_THRESH))
    return;
  
  //Insert new avg. values
  insert(mapped, avgs, AVGLEN); 
  insert(avg, long_avg, LONG_SECTOR); 

  //Compute the "song average" sensor value
  song_avg += avg;
  iter++;
  if (iter > CYCLES) {  
    song_avg = song_avg / iter;
    iter = 1;
  }
    
  longavg = compute_average(long_avg, LONG_SECTOR);

  //Check if we enter HIGH mode 
  check_high(longavg);  

  if (songmode == HIGH) {
    fade_scale = 3;
    Color.r = 5;
    Color.g = 3;
    Color.b = -1;
  }
  else if (songmode == NORMAL) {
    fade_scale = 2;
    Color.r = -1;
    Color.b = 2;
    Color.g = 1;
  }

  //Decides how many of the LEDs will be lit
  curshow = fscale(MIC_LOW, MIC_HIGH, 0.0, (float)NUM_LEDS, (float)avg, -1);

  /*Set the different leds. Control for too high and too low values.
          Fun thing to try: Dont account for overflow in one direction, 
    some interesting light effects appear! */
  for (int i = 0; i < NUM_LEDS; i++) 
    //The leds we want to show
    if (i < curshow) {
      if (leds[i].r + Color.r > 255)
        leds[i].r = 255;
      else if (leds[i].r + Color.r < 0)
        leds[i].r = 0;
      else
        leds[i].r = leds[i].r + Color.r;
          
      if (leds[i].g + Color.g > 255)
        leds[i].g = 255;
      else if (leds[i].g + Color.g < 0)
        leds[i].g = 0;
      else 
        leds[i].g = leds[i].g + Color.g;

      if (leds[i].b + Color.b > 255)
        leds[i].b = 255;
      else if (leds[i].b + Color.b < 0)
        leds[i].b = 0;
      else 
        leds[i].b = leds[i].b + Color.b;  
      
    //All the other LEDs begin their fading journey to eventual total darkness
    } else {
      leds[i] = CRGB(leds[i].r/fade_scale, leds[i].g/fade_scale, leds[i].b/fade_scale);
    }
  FastLED.show(); 
}
//Compute average of a int array, given the starting pointer and the length
int compute_average(int *avgs, int len) {
  int sum = 0;
  for (int i = 0; i < len; i++)
    sum += avgs[i];

  return (int)(sum / len);

}

//Insert a value into an array, and shift it down removing
//the first value if array already full 
void insert(int val, int *avgs, int len) {
  for (int i = 0; i < len; i++) {
    if (avgs[i] == -1) {
      avgs[i] = val;
      return;
    }  
  }

  for (int i = 1; i < len; i++) {
    avgs[i - 1] = avgs[i];
  }
  avgs[len - 1] = val;
}

//Function imported from the arduino website.
//Basically map, but with a curve on the scale (can be non-uniform).
float fscale( float originalMin, float originalMax, float newBegin, float
    newEnd, float inputValue, float curve){

  float OriginalRange = 0;
  float NewRange = 0;
  float zeroRefCurVal = 0;
  float normalizedCurVal = 0;
  float rangedValue = 0;
  boolean invFlag = 0;


  // condition curve parameter
  // limit range

  if (curve > 10) curve = 10;
  if (curve < -10) curve = -10;

  curve = (curve * -.1) ; // - invert and scale - this seems more intuitive - postive numbers give more weight to high end on output 
  curve = pow(10, curve); // convert linear scale into lograthimic exponent for other pow function

  // Check for out of range inputValues
  if (inputValue < originalMin) {
    inputValue = originalMin;
  }
  if (inputValue > originalMax) {
    inputValue = originalMax;
  }

  // Zero Refference the values
  OriginalRange = originalMax - originalMin;

  if (newEnd > newBegin){ 
    NewRange = newEnd - newBegin;
  }
  else
  {
    NewRange = newBegin - newEnd; 
    invFlag = 1;
  }

  zeroRefCurVal = inputValue - originalMin;
  normalizedCurVal  =  zeroRefCurVal / OriginalRange;   // normalize to 0 - 1 float

  // Check for originalMin > originalMax  - the math for all other cases i.e. negative numbers seems to work out fine 
  if (originalMin > originalMax ) {
    return 0;
  }

  if (invFlag == 0){
    rangedValue =  (pow(normalizedCurVal, curve) * NewRange) + newBegin;

  }
  else     // invert the ranges
  {   
    rangedValue =  newBegin - (pow(normalizedCurVal, curve) * NewRange); 
  }

  return rangedValue;
}