// Chaos on Trigger 

#include <stdint.h>
#include <avr/interrupt.h>
#include <avr/io.h>
#include <avr/pgmspace.h>

#include "sample.h"

#define LED_PIN     13
#define SPEAKER_PIN 11 

#define KNOB_1  (0)
#define KNOB_2  (1)  
#define KNOB_3  (2)   
#define INPUT3_PIN A3   // gate trigger

volatile uint16_t sample;
volatile uint16_t loop_start;
volatile uint16_t loop_length;
volatile uint16_t index_bounds;
volatile uint16_t loop_overflow;

volatile boolean gate;
volatile boolean gate_prev;
volatile boolean is_playing;

volatile uint16_t time_since_gate;

bool triggered;

int i=0;

byte lastSample;

void startPlayback()

{
    pinMode(SPEAKER_PIN, OUTPUT);

    // Set up Timer 2 to do pulse width modulation on the speaker pin.
    // Use internal clock (datasheet p.160)
    ASSR &= ~(_BV(EXCLK) | _BV(AS2));

    // Set fast PWM mode  (p.157)
    TCCR2A |= _BV(WGM21) | _BV(WGM20);
    TCCR2B &= ~_BV(WGM22);

    // Do non-inverting PWM on pin OC2A (p.155)
    // On the Arduino this is pin 11.
    TCCR2A = (TCCR2A | _BV(COM2A1)) & ~_BV(COM2A0);
    TCCR2A &= ~(_BV(COM2B1) | _BV(COM2B0));
    // No prescaler (p.158)
    TCCR2B = (TCCR2B & ~(_BV(CS12) | _BV(CS11))) | _BV(CS10);

    // Set initial pulse width to the first sample.
    OCR2A = pgm_read_byte(&sound_data[0]);

    // Set up Timer 1 to send a sample every interrupt.
    cli();

    // Set CTC mode (Clear Timer on Compare Match) (p.133)
    // Have to set OCR1A *after*, otherwise it gets reset to 0!
    TCCR1B = (TCCR1B & ~_BV(WGM13)) | _BV(WGM12);
    TCCR1A = TCCR1A & ~(_BV(WGM11) | _BV(WGM10));

    // No prescaler (p.134)
    TCCR1B = (TCCR1B & ~(_BV(CS12) | _BV(CS11))) | _BV(CS10);

    // Set the compare register (OCR1A).
    // OCR1A is a 16-bit register, so we have to do this with
    // interrupts disabled to be safe.
    OCR1A = F_CPU / SAMPLE_RATE; // 16e6 / 8000 = 2000

    // Enable interrupt when TCNT1 == OCR1A (p.136)
    TIMSK1 |= _BV(OCIE1A);

    lastSample = pgm_read_byte(&sound_data[sound_length - 1]);
    sample = 0;
    sei();
}

void stopPlayback()
{
    TIMSK1 &= ~_BV(OCIE1A); // Disable playback per-sample interrupt.
    TCCR1B &= ~_BV(CS10);   // Disable the per-sample timer completely.
    TCCR2B &= ~_BV(CS10);   // Disable the PWM timer.
    digitalWrite(SPEAKER_PIN, LOW);
}

void setup()
{
    pinMode(LED_PIN, OUTPUT);
    digitalWrite(LED_PIN, HIGH);

    startPlayback();

    loop_start = 0; 
    loop_length = sound_length;
    gate = false;
    gate_prev = false;
    is_playing = false;
    time_since_gate = 0;
}

// This is called at 8000 Hz to load the next sample.
ISR(TIMER1_COMPA_vect)
{

	if (gate == true && gate_prev == false)
	
	  {
		time_since_gate = 0;
		sample = loop_start;
		is_playing = true;
  	}

	gate_prev = gate;
	time_since_gate++;

	if (time_since_gate >= 8000 * 20)
	{

		is_playing = false;
	}

	if (is_playing)
	{

	    OCR2A = pgm_read_byte(&sound_data[sample % sound_length]);
	    sample++;

	    if(sample >= index_bounds)
	    {
	        sample = loop_start;
	    }
	    else if((sample < loop_start) &&
	            (sample >= loop_overflow))
	    {
	        sample = loop_start;}
	} 
	
	else 
	{
  OCR2A = pgm_read_byte(&sound_data[0]);
	}
}

void loop()

{  
  gate = analogRead(A3) << 9;
  if (gate && !triggered)
  {
    loop_start = random(0,1023) / 1024.0 * random(100,11461);  
  delay(500); 
  loop_length = (analogRead(KNOB_2) + 1) / 1024.0 * sound_length;
  OCR1A = (512.0 / (analogRead(KNOB_3) + 1)) * (F_CPU / SAMPLE_RATE);
	gate = analogRead(3) ;

	triggered=true;
  }

  else if(!gate && triggered)
  {triggered=false;}

  
//  can be up to 2x sound length. the more you know.
    index_bounds = loop_start + loop_length;
    //Serial.println(loop_length);
//  this will set the overflow length. take the loop overflow into account when checking the loop boundaries
    if(index_bounds > sound_length)
    {
        loop_overflow = index_bounds - sound_length;
    }
    else
    {
        loop_overflow = 0;
    }
}