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

#include "lights.h"

/* ADC numbering: PWM LEDs first, then ambient light sensor, battery sensor */
static unsigned char adc_mux[] = { // pwmleds should be first
	// 0: pwmled 0: 1.1V, ADC3 (PA4), single-ended
	_BV(REFS1) | _BV(MUX1) | _BV(MUX0),
	// 1: pwmled 1: 1.1V, ADC0,1 (PA0,1), gain 1 or 8
	_BV(REFS1) | _BV(MUX3) | _BV(MUX2),
	// 2: pwmled 2: 1.1V, ADC2,1 (PA2,1), gain 20 or 32
	_BV(REFS1) | _BV(MUX3) | _BV(MUX2) | _BV(MUX1),
	// 3: ambient light: 1.1V, ADC4 (PA5), single-ended
	_BV(REFS1) | _BV(MUX2),
	// 4: batt voltage: 1.1V, ADC5 (PA6), single-ended
	_BV(REFS1) | _BV(MUX2) | _BV(MUX0),
};

#define AMBIENT_ADC N_PWMLEDS
#define BATTERY_ADC (N_PWMLEDS + 1)

#define LAST_ADC (sizeof(adc_mux)/sizeof(adc_mux[0]))
volatile static unsigned char current_adc;
static unsigned char adc_ignore;

static void start_next_adc()
{
	while (current_adc > 0) {
		--current_adc;

		// test if current_adc should be measured
		if (current_adc < N_PWMLEDS && pwmled_needs_adc(current_adc))
			goto found;
		if (current_adc == AMBIENT_ADC)
			goto found;
		// TODO battery sense, etc.
	}

	// all ADCs have been handled
	current_adc = LAST_ADC;
	return;
found:
	// ADCSRB |= _BV(GSEL); // gain 8 or 32
	ADMUX = adc_mux[current_adc]; // set up mux, start one-shot conversion
	adc_ignore = 1; // ignore first reading after mux change
	ADCSRA |= _BV(ADSC);
}

void init_adc()
{
	current_adc = LAST_ADC;
	adc_ignore = 1;

	ADCSRA = _BV(ADEN)			// enable
		| _BV(ADPS1) | _BV(ADPS0)	// CLK/8 = 125 kHz
		// | _BV(ADPS2)			// CLK/16 = 62.5 kHz
		;
	ADCSRB |= _BV(GSEL); // gain 8 or 32

	// Disable digital input on all bits used by ADC
	DIDR0 = _BV(ADC0D) | _BV(ADC1D) | _BV(ADC2D) | _BV(ADC3D)
		| _BV(ADC4D) | _BV(ADC5D);

	ADCSRA |= _BV(ADSC);

	/* Do first conversion and drop the result */
	while ((ADCSRA & _BV(ADIF)) == 0)
		;
	ADCSRA |= _BV(ADIF); // clear the IRQ flag

	ADCSRA |= _BV(ADIE); // enable IRQ
}

ISR(ADC_vect) { // IRQ handler
	uint16_t adcval = ADCW;

#if 0
	log_byte(0xF3);
	log_byte(current_adc);
	log_word(adcval);
#endif

	if (adc_ignore) {
		ADCSRA |= _BV(ADSC);
		adc_ignore = 0;
		return;
	}

	if (current_adc < N_PWMLEDS)
		pwmled_adc(current_adc, adcval);
	if (current_adc == AMBIENT_ADC)
		ambient_adc(adcval);
	// TODO battery sense, etc.
	
	start_next_adc();
}

void timer_start_adcs()
{
	if (current_adc == LAST_ADC) // Don't start if in progress
		start_next_adc();
}