#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 = 0x10;
volatile uint16_t adc_exp = 0x10;
unsigned char led_is_on = 0;
volatile unsigned char adccount = 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 );
	led_is_on = 1;
}

static void inline led_off()
{
	led_is_on = 0;
        DDRB &= ~_BV( PB5 );
//        ADCSRA &= ~(_BV(ADIE) | _BV(ADIF));
}

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

unsigned char debug_state EEMEM;

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

#define LOG_BUFFER 64
uint16_t log_buffer[LOG_BUFFER] EEMEM;
unsigned char log_buffer_count;
uint16_t log_buffer2[LOG_BUFFER];
volatile unsigned char stop = 0;

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)
		return;
	
	// eeprom_write_word(&log_buffer[log_buffer_count], word);
	log_buffer2[log_buffer_count] = word;
	log_buffer_count++;

	if (log_buffer_count == LOG_BUFFER) {
		unsigned char i;
		for (i=0; i < LOG_BUFFER; i++) {
			eeprom_write_word(&log_buffer[i],
				log_buffer2[i]);
		}
		debug_setstate(0x42);
	}
}

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

volatile uint16_t clock = 0;

static void inline init_tmr()
{
	TCCR0A = _BV(WGM00);
	TCCR0B = _BV(CS02) | _BV(CS00); // 1 kHz
	OCR0A = 12; // 100 Hz
	TIMSK |= _BV(OCIE0A);
	DDRA |= _BV( PA0 );

	clock = 0;
}

static void inline tmr_handler()
{
	unsigned char c = clock & 0x1F;
	unsigned char c1 = clock & 0xFF;

	++clock;
#if 0
	if (c == 10 || c == 30) 
		led_on();

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

	if (c == 0x02 || c == 0x08)
		led_on();
	if (c == 0x05 || c == 0x0b)
		led_off();

	if ((clock & 0x7F) == 0x1F) {
		if (c1 < 0x80) {
			adc_exp = 0x80;
		} else {
			adc_exp = 0x20;
		}
	}
	ADCSRA |= _BV(ADSC);
#if 0
	if (led_is_on && adcval != 0xFFEE) {
		adcval = 0xFFEE;

		ADCSRA |= _BV(ADIF) | _BV(ADIE) | _BV(ADSC);
	}
#endif
}

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 = _BV(7)				// PWM1X: PWM inversion mode
		| _BV(CS10) 			// no clock prescaling
		;
	OCR1C = 0xFF;				// TOP value
	OCR1D = OCR1B = OCR1A = pwmval;
	// OCR1D = 0;
	// DDRB |= _BV( PB5 );
	PORTB &= ~(_BV( PB5 ) | _BV( PB1 ) | _BV( PB3 ));

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

#if 0
static void inline pwm_handler()
{
	// TIMSK &= ~_BV(TOIE1);
	// OCR1D = pwmval;
}

ISR(TIMER1_OVF_vect)
{
	pwm_handler();
}
#endif

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

static void inline init_adc()
{
	ADCSRA = _BV(ADEN)			// enable
		| _BV(ADPS1) | _BV(ADPS0)	// CLK/8 = 125 kHz
		// | _BV(ADPS2)			// CLK/16 = 62.5 kHz
		;
	ADMUX = _BV(REFS1)			// 1.1V internal reference
		| _BV(MUX4)|_BV(MUX3)	// port ADC5-6, gain 1
		;
	// ADCSRB = _BV(REFS2); 
	ADCSRB |= _BV(GSEL); 
	// Disable digital input on all bits used by ADC
	DIDR0 = _BV(ADC5D)|_BV(ADC6D) | _BV(AREFD);
	ADCSRA |= _BV(ADIE);
}

static void inline adc_handler()
{
	uint16_t new_pwm = pwmval;
	uint16_t old_pwm = pwmval;
	uint16_t old_adc = adcval;
	adcval = ADCW;
	adccount++;

	// log_word(((adcval & 0x3FC) << 6) | pwmval);
	log_word(((adcval & 0xFF) << 8) | pwmval);

	if (!led_is_on)
		return;
	// adcval = (adcval + 3*old_adc)/4;

	// ADCSRA &= ~(_BV(ADIE) | _BV(ADIF));

	if (adcval < 1) {
		adcval = 1;
	} else if (adcval > adc_exp) {
		new_pwm = old_pwm*adc_exp/adcval;
	} else if (adcval < adc_exp && 2 * adcval > adc_exp) {
		new_pwm = old_pwm*adc_exp/adcval;
	} else if (adcval < adc_exp) {
		new_pwm = 2 * old_pwm;
	}

	new_pwm = (3*old_pwm + new_pwm) / 4;
	if (new_pwm > 0x60) { // odpojeno?
		new_pwm = 0x60;
	}
	if (new_pwm < 2) { // zkrat?
		new_pwm = 2;
	}

	// if (new_pwm < 15*old_pwm/16 || new_pwm > 17*old_pwm/16) {
		pwmval = new_pwm;
		OCR1D = pwmval;
	// }
	// ADCSRA |= _BV(ADSC);
}

ISR(ADC_vect)
{
	adc_handler();
}

int main(void)
{
	init_log();

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

	debug_setstate(2);

	sei();
	while (1)
		;// sleep_mode();

#if 0
    DDRA |= _BV( PA0 );
    while( 1 ) { 
        PORTA |=  _BV( PA0 );
        _delay_ms(200);
        PORTA &=~ _BV( PA0 );
    }
#endif
}