/* Tone Generator
 * -----------
 *
 * Program to play a tone based upon turned knobs.
 * By Tom Music
 *
 */

// SETUP ============================================
  // Digital Pins
#define pinSpeaker      11
#define pinStartStop    12
#define pinPlaySandbox  3
  // Analog Pins
#define pinTone         0
#define pinDuration     1

// Note frequencies are seperated by octave, starting with G2.
// 0 is used as a value to denote a rest.
// These values are all multiplied by 10 to increase resolution and still fit in a whole number
long noteList[] = {
  0,
  980, 1038, 1100, 1165, 1235,
  1308, 1386, 1468, 1556, 1648, 1756, 1850, 1960, 2076, 2200, 2331, 2469,
  2616, 2772, 2937, 3111, 3296, 3492, 3700, 3920, 4153, 4400, 4662, 4939,
  5232, 5544, 5873, 6222, 6593, 6985, 7400, 7840, 8306, 8800, 9323, 9878,
  10460, 11090, 11750, 12450, 13190, 13970, 14800, 17600, 18650, 19790,
  20930, 22170, 23490, 24890, 26370, 27940, 29600, 31360, 33220, 35200, 37290, 39510,
  41860}; 

int noteCount = 0;

void setup() { 
  pinMode(pinSpeaker, OUTPUT);
  pinMode(pinStartStop, INPUT);
  pinMode(pinPlaySandbox, INPUT);

  digitalWrite(pinPlaySandbox, HIGH);

    // Sizeof() returns bytes, and this is an array of Longs (which are 4 bytes each)
  noteCount = sizeof(noteList) / 4;

    // Notify user of processor boot via serial connection
  Serial.begin(9600);
  Serial.print ("I'm awake!");
  Serial.println();
}

// ========== PLAY A TONE USING PULSE WIDTH MODULATION
void playTone(long toneValue, long toneDuration) {
  long elapsedTime = 0;
  long tonePeriods = 0;
  
  tonePeriods = (10000000 / toneValue);

  // Tones of 0 represent rests, anything higher gets played
  if (toneValue > 0) {
    while (elapsedTime < toneDuration) {

      // Sound waves are created by pulsing the speaker between high and low
      digitalWrite(pinSpeaker, HIGH);
      delayMicroseconds(tonePeriods / 2);
      digitalWrite(pinSpeaker, LOW);
      delayMicroseconds(tonePeriods / 2);

      // Keep track of how long we have pulsed, so we know when to stop
      elapsedTime += (tonePeriods);
    } 
  }                                 
}

// ========== SCALE INPUT VALUES
// Modified by Tom Music from source available here:
// http://www.arduino.cc/playground/Main/Autoscale
long autoScale(long originalMin, long originalMax, long newBegin, long newEnd, long inputValue) {
  long zeroRefOriginalMax = 0;
  long zeroRefnewEnd = 0;
  long zeroRefCurVal = 0;
  long rangedValue = 0;
  boolean invFlag = 0;

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

  if (inputValue > originalMax) {
    inputValue = originalMax;
  }

  // Zero-reference the values
  zeroRefOriginalMax = originalMax - originalMin;

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

  zeroRefCurVal = inputValue - originalMin;

  if (originalMin > originalMax ) {
    return 0;
  }

  if (invFlag == 0) {
    rangedValue =  ((zeroRefCurVal * zeroRefnewEnd) / zeroRefOriginalMax) + newBegin; 
  } else {    // invert the ranges
    rangedValue =  newBegin - ((zeroRefCurVal * zeroRefnewEnd) / zeroRefOriginalMax); 
  }

  return rangedValue;
} 

// ========== MAIN EXECUTION LOOP
void loop() {
  long currentTone = 0;
  long currentDuration = 0;
  long bufferTone = 0;
  long bufferDuration = 0;

  long currentTempo = 10000;

// - Not used yet
//  long pauseBetweenNotes = 1000;

// - Not used yet
//  int playSandbox = true;

// - Not used yet
//  playSandbox = digitalRead(pinPlaySandbox);

  bufferTone = analogRead(pinTone);
  bufferDuration = analogRead(pinDuration);
  
  bufferTone = autoScale(0, 1023, 0, noteCount - 1, bufferTone);
  currentTone = noteList[bufferTone];
  currentDuration = autoScale(0, 1023, 0, 128, bufferDuration);
  
// - Not used yet
//  if (playSandbox == LOW) {

//  Debugging Code
//    Serial.print (noteCount);
//    Serial.print ("\t");
//    Serial.print (bufferTone);
//    Serial.print ("\t");
//    Serial.print (currentTone);
//    Serial.print (currentDuration);
//    Serial.println();
    playTone(currentTone, currentDuration * currentTempo);
//  }

// - Not used yet
//  delayMicroseconds(pauseBetweenNotes);
}