gistfile1.txt

#include "tables.h"
#include <MIDI.h>


MIDI_CREATE_DEFAULT_INSTANCE();


#define FS 20000.0    // sample rate in hz
#define ledPin 13


class SynthVoice {
private:
  volatile unsigned int phase;
  volatile unsigned int tuning_word;
  volatile unsigned char level;
  volatile unsigned int frequency;
  volatile const char *wave;

public:
  SynthVoice() {
    this->phase = 0;
    this->tuning_word = 1000;
    this->level = 255;
    this->frequency = 500;
    this->wave = (const char *)SinTable;
  }

  void setFrequency(float f)
  {
    this->frequency = f / (FS/65535.0);
  }
  void setNote(unsigned char MIDInote)
  {
    this->frequency = pgm_read_word(PITCHS + MIDInote);
    this->tuning_word = this->frequency + (int)((this->frequency >> 6) / 128);   
  }
  void setWave(char *wave) 
  {
    this->wave = wave;
  }

  signed char nextSample()
  {
    return ((signed char)pgm_read_byte(this->wave + ((unsigned char *)&(this->phase += this->tuning_word))[1]) * this->level) >> 8;
  }
  
};

SynthVoice *voices[4];



void HandleNoteOn(byte channel, byte pitch, byte velocity) 
{ 
  // Do something here with your data!
  voices[0]->setNote(pitch);
}

void HandleCC(byte channel, byte pitch, byte velocity) 
{
  // Do something here with your data!
}

void HandleNoteOff(byte channel, byte pitch, byte velocity) 
{
  // Do something here with your data!
}


void setup() {
  pinMode(ledPin, OUTPUT);

  voices[0] = new SynthVoice();
  voices[0]->setNote(60);


  voices[1] = new SynthVoice();
  voices[1]->setNote(63);

  voices[2] = new SynthVoice();
  voices[2]->setNote(67);
  
  voices[2] = new SynthVoice();
  voices[2]->setNote(70);
 

  //setup audio interrupt on TIMER1
  TCCR1A = 0x00;
  TCCR1B = 0x09;
  TCCR1C = 0x00;
  OCR1A = 16000000.0 / FS;  // sample rate
  TIMSK1 |= (1<<OCIE1A);
  sei();

  //8-bit audio pwm
  TCCR2A = 0xB3;
  TCCR2B = 0x01;
  OCR2A = OCR2B = 127;
  DDRB |= 1<<3;
  DDRD |= 1<<3;


  //midi handlers
  MIDI.begin(MIDI_CHANNEL_OMNI);
  MIDI.setHandleNoteOn(HandleNoteOn);
  MIDI.setHandleControlChange(HandleCC);
  MIDI.setHandleNoteOff(HandleNoteOff);  

}

void loop() {
  MIDI.read();
}


        
SIGNAL(TIMER1_COMPA_vect)
{
  OCR2A = OCR2B = 127 + (
      (
        voices[0]->nextSample() 
        +voices[1]->nextSample() 
        +voices[2]->nextSample() 
        +voices[3]->nextSample()
        
      ) >> 2
  );
}