#include <avr/io.h>
#include <avr/eeprom.h>
#include <util/delay.h>
#include <avr/sleep.h>
#include <avr/interrupt.h>

volatile uint16_t adcval;
unsigned char pwmval = 0x28;
uint16_t pwmints = 0;

volatile struct
{
  uint8_t pwm_int: 1;
  uint8_t adc_int: 1;
  uint8_t tmr_int: 1;
}
intflags;

static void inline led_on()
{
        DDRB |= _BV( PB5 );
}

static void inline led_off()
{
        DDRB &= ~_BV( PB5 );
}

/* ------------ Logging/Debugging ----------- */

unsigned char debug_state EEMEM;

static void inline debug_setstate(unsigned char val)
{
	eeprom_write_byte(&debug_state, val);
}

#define LOG_BUFFER 192
uint16_t log_buffer[LOG_BUFFER] EEMEM;
uint16_t log_buffer_count;

static void inline init_log()
{
	debug_setstate(1);
	log_buffer_count = 0;
}

static void log_word(uint16_t word) {
	if (log_buffer_count == LOG_BUFFER) {
                debug_setstate(0x42);
		log_buffer_count++;
	}
	if (log_buffer_count >= LOG_BUFFER)
		return;
	
	eeprom_write_word(&log_buffer[log_buffer_count], word);
	log_buffer_count++;
}

/* ------------ Timer ----------- */

uint16_t clock = 0;

static void inline init_tmr()
{
	TCCR0A = _BV(WGM00);
	TCCR0B = _BV(CS02) | _BV(CS00); // 1 kHz
	OCR0A = 10; // 100 Hz
	TIMSK |= _BV(OCIE0A);
	DDRA |= _BV( PA0 );

	clock = 0;
}

static void inline tmr_handler()
{
	unsigned char c = clock & 0x7F;
	++clock;

	if (c == 10 || c == 30) 
		led_on();

	if (c == 20 || c == 40)
		led_off();

	log_word(adcval);
	if (adcval != 0xFFEE) {
		adcval = 0xFFEE;

		ADCSRA |= _BV(ADIE) | _BV(ADSC);
	}
}

ISR(TIMER0_COMPA_vect)
{
	tmr_handler();
}

/* ------------ PWM ----------- */

static void inline init_pwm()
{
	/* Async clock */
	PLLCSR = _BV(LSM) | _BV(PLLE);
	_delay_ms(1);
	while (PLLCSR & _BV(PLOCK) == 0)
		;
	PLLCSR |= _BV(PCKE);

	TCCR1C = _BV(COM1D0) | _BV(COM1D1) | _BV(PWM1D);
	TCCR1A = _BV(COM1A0) | _BV(COM1A1) | _BV(COM1B0) | _BV(COM1B1) | _BV(PWM1A) | _BV(PWM1B);
	// TCCR1B = 0x80| _BV(CS13) | _BV(CS11);
	TCCR1B = 0x80 | _BV(CS10);
	OCR1C = 0xFF;
	OCR1D = OCR1B = OCR1A = pwmval;
	TCNT1 = 0;
	DDRB |= _BV( PB5 );
	PORTB &= ~(_BV( PB5 ) | _BV( PB1 ) | _BV( PB3 ));

	led_off();
	// TIMSK |= _BV(TOIE1);
}

#if 0
static void inline pwm_handler()
{
	TCNT1 = 0;
	OCR1D = pwmval;
}

ISR(TIMER1_OVF_vect)
{
	TIMSK &= ~_BV(TOIE1);
	pwm_handler();
}
#endif

/* ------------ A/D Converter ----------- */

static void inline init_adc()
{
	ADCSRA = _BV(ADEN) | _BV(ADATE) | _BV(ADPS1) | _BV(ADPS0);
	ADMUX = _BV(REFS1) | _BV(MUX0);
	// ADCSRB = _BV(REFS2); 
	DIDR0 = _BV(ADC1D) | _BV(AREFD);
}

static void inline adc_handler()
{
	static unsigned char last_pwmval = 0;
	static unsigned char counter = 0;
	uint16_t tmp = pwmval;
	static uint16_t discard = 5;

	adcval = ADCW;
	ADCSRA &= ~_BV(ADIE);         /* disable ADC interrupt */
#if 0
	if (--discard > 0)
		goto out;

	if (adcval > 0x300)
		tmp = 3*tmp/4;
	else if (adcval > 0x280)
		tmp = 7*tmp/8;
	else if (adcval > 0x201)
		tmp--;
	else if (adcval < 0x100)
		tmp = 5*tmp/4;
	else if (adcval < 0x180)
		tmp = 9*tmp/8;
	else if (adcval < 0x1ff)
		tmp++;

	if (tmp > 0xFF)
		tmp = 0xFF;
	if (tmp == 0)
		tmp = 1;

	counter++;
	if ((last_pwmval > tmp && last_pwmval - tmp > 10)
		|| (last_pwmval < tmp && tmp - last_pwmval > 10)
		|| (counter > 2)) {
		counter = 0;
	
		if (rv_count < BUFFER-1) {
			eeprom_write_word(&readval[rv_count++], adcval);
			eeprom_write_word(&readval[rv_count++], pwmval);
			if (rv_count >= BUFFER)
				eeprom_write_byte(&debug, 42);
		}
	}

	last_pwmval = pwmval;
	pwmval = tmp;

	if (pwmval != last_pwmval) {
		TIMSK |= _BV(TOIE1);
		
		discard = 1000;
	} else {
		discard = 0;
	}

out:
	//TIMSK |= _BV(TOIE1);
	ADCSRA |= _BV(ADIE) | _BV(ADSC);
#endif
}

ISR(ADC_vect)
{
	adc_handler();
}

#if 0
	if (--pcount == 0) {
		ppos++;
		pcount = pattern[ppos].length;
		if (!pcount) {
			ppos = 0;
			pcount = pattern[ppos].length;
		}
		if (pattern[ppos].intensity) {
			PORTA |= _BV(PA0);
		} else {
			PORTA &= ~_BV(PA0);
		}
	}
#endif

int main(void)
{
	char seen = 0;
	char pcount, ppos;
	unsigned char adcidx = 0;
	uint16_t adcvals[16];

	init_log();

	init_pwm();
	init_adc();
	init_tmr();

	debug_setstate(2);

	sei();
	while (1)
		; //sleep_mode();
#if 0
		if (!seen) {
			seen = 1;
			eeprom_write_byte(&debug, 2);
		}
#endif

    DDRA |= _BV( PA0 );
    while( 1 ) { 
        PORTA |=  _BV( PA0 );
        _delay_ms(200);
        PORTA &=~ _BV( PA0 );
    }
}