// Better sequencer which uses interrupts

#include <Adafruit_MCP4728.h>
#include <Wire.h>

Adafruit_MCP4728 mcp;
#define nsamp 1500
#define dacmax 256


float tuning[37];
float voltrange = 4.85;  // measured this, probably not accurate
float octave = 4096.0 / voltrange; // number of DAC steps in an octave

byte waveform[nsamp];

// melody

// int pitch[] = { 4, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
// -1, -1, -1, -1, -1, -1, -1, -1,-1, -1, -1, -1,2, -1, -1, -1, };
// int dur[] = { 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
//             0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0,  };

// melody

int pitch[] = { 1, -1, -1, -1, -1, -1, -1, -1, };
int sequence[] = { 97, 98, 99, 100, 101, 102, 103, 104,105,};
float dur[] = { 0.4, 0.4, 0.4, 0.4, 0.4, 0.4, 0.4, 0.4, };


// bass 


unsigned int phase = 0;
unsigned int fibo = 3;
unsigned int scale = 0;
unsigned int fibi = 0;
unsigned int gate = 4095;
unsigned int pmax = nsamp;
unsigned int beat = 0;


int note = 0;
int phrase = 16;

int s;
int bpm = 220;
float beat_s = 60.0 / (float)bpm;
float beat_m = 1000.0 * beat_s; 
bool noteon = false;
long notestart, notedur, barstart;
float xlog = 0.75;
float r = 0;

void setup() {
  Serial.begin(115200);

  float freqint = (float)bpm/ 60.0;

  int ocr = round(16000000.0 / (1024.0 * freqint)) - 1;
  Serial.println(ocr);
  if( ocr < 65536 ) {

    cli();

    TCCR1A = 0;// set entire TCCR1A register to 0
    TCCR1B = 0;// same for TCCR1B
    TCNT1  = 0;//initialize counter value to 0
    OCR1A = ocr; 
    // turn on CTC mode
    TCCR1B |= (1 << WGM12);
    // Set CS10 and CS12 bits for 1024 escaler
    TCCR1B |= (1 << CS12) | (1 << CS10);  
    // enable timer compare interrupt
    TIMSK1 |= (1 << OCIE1A);

    sei();

  } else {
    Serial.println("BPM out of range");
  }

  if (!mcp.begin(0x64)) {
    while (1) {
      delay(100);
    }
  }
  for( int i = 0; i < nsamp; i++ ) {
    waveform[i] = 1;
  }
  fibi = 3;
  fibo =  3; //fibosort[fibi];
  setwave();

  // randomSeed(analogRead(A0));
  mcp.setSpeed(800000L);
  note=0;
  barstart=millis();


}

void setwave(){
  waveform[0] = 0;
  waveform[1] = 1;
  fibo = fibi; // fibosort[fibi];// + 3;
  pmax = nsamp;
  for (int i=2; i<nsamp; ++i){
    waveform[i] = (waveform[i - 1] + waveform[i - 2]) % fibo;
    if( waveform[i - 1] == 0 && waveform[i] == 1 ) {
      pmax = i - 1;
      break;
    }
  }
  float scale = 256 / fibo;
  for( int i = 0; i < nsamp; ++i ) {
    waveform[i] *= scale;
  }
}



// mod_note argument is milliseconds from the start of last note
float mod_note(int x) {
  float xb = x / (0.2 * beat_m);
  return 0.5 + 0.5 * xb * (xb - 1) * ( xb - 2);
}

// mod_note argument is milliseconds from the start of this bar
float mod_bar(int x) {
  return 0.5 + 0.5 * sin((float)x / (beat_m));
}

void set_mod(MCP4728_channel_t channel, float v) {
  int o;
  o = round(v * 4095.0);
  if( o > 4095 ) {
    o = 4095;
  }
  if( o < 0 ) {
    o = 0;
  } 
  mcp.setChannelValue(channel, o);
}

ISR(TIMER1_COMPA_vect){ // called once every beat
  note++;
  if( note == phrase ) {
    note = 0;
  }
  fibi = sequence[note];
  beat = true;
  setwave();
  phase = 0;
}


void loop() {
  float mod;
  int o;
  long now = millis();
  if( beat ) {
    beat = false;
    if( pitch[note] > -1 ) {
      notestart = millis();
      notedur = round(beat_m * dur[s]);
      Serial.println(notedur);
      gate = 4095;
    }
  } else {
    if( gate ) {
      if( now - notestart > notedur ) {
        gate = 0;
      }
    }
    mcp.fastWrite(waveform[phase] << 4, gate, 0, 0);
    phase += 1;
    if( phase == pmax ) {
      phase = 0;
    }
  }
}


void noteOn(int note) {
  if( note > -1 ) {
    mcp.setChannelValue(MCP4728_CHANNEL_B, 4095);
  }
}

void noteOff() {
    mcp.setChannelValue(MCP4728_CHANNEL_B, 0);
}