#include <avr/io.h>

#include "lights.h"

typedef struct {
	uint16_t target, pwm;
	int16_t err_sum;
	unsigned char mode, state;
	union {
		unsigned char probe_steady, mode_changed;
	};
	uint16_t mode_pwm[N_PWMLED_MODES];
	int16_t err_sums[N_PWMLED_MODES];
	unsigned char modes_not_yet_stable;
} pwmled_t;

pwmled_t pwmleds[N_PWMLEDS];

/*
 * Mode stabilization:
 * when changing brightness via pwmled_set_brightness() below,
 * we want to converge to the target value as fast as possible. Also,
 * we would like to somehow initialize the mode 3, which is used as
 * "mode 2 + other PWMLED on". So after the brightness is set,
 * we also set pwmleds[n].modes_not_yet_stable to MODE_STABILIZATION_TIME.
 * When modes_not_yet_stable is non-zero, we allow only mode 2 to be set
 * regardless of what is fed to pwmled_set_mode. We will then converge
 * to the target value of mode 2 only, and after MODE_STABILIZATION_TIME
 * ADC measurements, we copy the mode_pwm value to all other modes.
 * Only then it is allowed to set the other modes.
 */
#define MODE_STABILIZATION_TIME	(2*16)	// two seconds worth of measurements

#define PWMLED2_TESTING_WITH_350MA_LED

#define SENSE_MOHM	33	/* 0.033 Ohm */
/*
 * Voltage in uV at ADC reading == 1 is 1100/gain/1024
 * ADC module returns sum of 1 << PWMLED_ADC_SHIFT measurements
 * Voltage in uV measured is current in mA * sense resistance in mOhm
 */
#define MA_GAIN_TO_ADC(ma, gain) ((uint16_t) \
	((uint32_t)(ma) \
	* (SENSE_MOHM) \
	* (1 << (PWMLED_ADC_SHIFT)) \
	* 1024 \
	/ (1100000/(gain))))

static uint16_t adc_max[N_PWMLEDS] = {
#ifdef TESTING_FW
	MA_GAIN_TO_ADC( 400, 20),
	MA_GAIN_TO_ADC(  30, 20),
	MA_GAIN_TO_ADC( 800,  1)
#else
	MA_GAIN_TO_ADC( 900, 20),
	MA_GAIN_TO_ADC(  30, 20),
	MA_GAIN_TO_ADC(2500,  1)
#endif
};

static uint16_t adc_targets_0[] = {
	MA_GAIN_TO_ADC(  50, 20),
	MA_GAIN_TO_ADC(  80, 20),
	MA_GAIN_TO_ADC( 160, 20),
	MA_GAIN_TO_ADC( 350, 20),
};

static uint16_t adc_targets_1[] = {
	MA_GAIN_TO_ADC(   5, 20),
	MA_GAIN_TO_ADC(  10, 20),
	MA_GAIN_TO_ADC(  20, 20),
};

static uint16_t adc_targets_2[] = {
#ifdef TESTING_FW
	MA_GAIN_TO_ADC( 120,  1),
	MA_GAIN_TO_ADC( 160,  1),
	MA_GAIN_TO_ADC( 240,  1),
	MA_GAIN_TO_ADC( 320,  1),
	MA_GAIN_TO_ADC( 460,  1),
#else
	MA_GAIN_TO_ADC( 150,  1),
	MA_GAIN_TO_ADC( 300,  1),
	MA_GAIN_TO_ADC( 500,  1),
	MA_GAIN_TO_ADC( 700,  1),
	MA_GAIN_TO_ADC(1500,  1),
	MA_GAIN_TO_ADC(2500,  1),
#endif
};

static uint16_t adc_vals[N_PWMLEDS*N_PWMLED_MODES];

#define ST_DISABLED 0
#define ST_OFF      1
#define ST_PROBING  2
#define ST_ON       3
// The above are constructed so that the following work:
#define ST_IS_ON(s)	((s) & 0x02)
#define ST_CAN_SET_MODE(s)	((s) & 0x01)

void init_pwmled()
{
	unsigned char i, j;

	for (i = 0; i < N_PWMLEDS; i++) {
		pwmled_t *led = pwmleds + i;
		led->err_sum = 0;
		led->target = adc_vals[i*N_PWMLED_MODES];
		led->mode = 1;
		led->probe_steady = 0;
		led->state = ST_OFF;
		led->pwm = 1;
		pwm_set(i, led->pwm);

		for (j = 0; j < N_PWMLED_MODES; j++) {
			led->mode_pwm[j] = 0;
			led->err_sums[j] = 0;
		}
	}

	pwmled_set_brightness(PWMLED_BRIGHTNESS(0, 2, 1, 0, 2));
}

void pwmled_set_mode(unsigned char n, unsigned char mode)
{
	pwmled_t *led = pwmleds + n;

	if (!ST_CAN_SET_MODE(led->state))
		return;

	if (led->mode) { // save the previous state
		led->mode_pwm[led->mode - 1] = led->pwm;
		led->err_sums[led->mode - 1] = led->err_sum;
	}

	led->mode = mode;

	if (mode > 0 && mode <= N_PWMLED_MODES) {
		if (led->modes_not_yet_stable) // only mode 2 when !stable
			mode = 2;
		led->target = adc_vals[n*N_PWMLED_MODES + mode - 1];
		led->state = ST_ON;
		led->pwm = led->mode_pwm[mode - 1];
		led->err_sum = led->err_sums[mode - 1];
		led->mode_changed = 1;
		pwm_set(n, led->pwm);
	} else {
		led->state = ST_OFF;
		pwm_off(n);
	}
}

#define CHECK_BRIGHTNESS(var, expr, array) \
	do { \
		(var) = (expr); \
		if ((var) >= sizeof(array)/sizeof(array[0])) \
			(var) = sizeof(array)/sizeof(array[0]) - 1; \
	} while (0)

void pwmled_set_brightness(uint16_t brightness)
{
	unsigned char i;

	CHECK_BRIGHTNESS(i, brightness & 0x7, adc_targets_0);
	adc_vals[0] = adc_targets_0[i];
	CHECK_BRIGHTNESS(i, (brightness >> 3) & 0x7, adc_targets_0);
	if (adc_vals[1] != adc_targets_0[i]) {
		adc_vals[1] = adc_targets_0[i];
		pwmleds[0].modes_not_yet_stable = MODE_STABILIZATION_TIME;
	}
	adc_vals[2] = adc_vals[1];

	CHECK_BRIGHTNESS(i, (brightness >> 6) & 0x7, adc_targets_1);
	// we use only one mode, so no modes_not_yet_stable handling here
	adc_vals[3] = adc_targets_1[i];
	adc_vals[4] = adc_vals[3];
	adc_vals[5] = adc_vals[3];

	CHECK_BRIGHTNESS(i, (brightness >> 9) & 0x7, adc_targets_2);
	adc_vals[6] = adc_targets_2[i];
	CHECK_BRIGHTNESS(i, (brightness >> 12) & 0x7, adc_targets_2);
	if (adc_vals[7] != adc_targets_2[i]) {
		adc_vals[7] = adc_targets_2[i];
		pwmleds[2].modes_not_yet_stable = MODE_STABILIZATION_TIME;
	}
	adc_vals[8] = adc_vals[7];

	for (i = 0; i < N_PWMLEDS; i++) {
		pwmleds[i].err_sum = 0;
		pwmled_set_mode(i, pwmleds[i].mode);
	}
}

#define PWMLED_PROBE_STEADY_COUNT 10

static inline unsigned char pwmled_probed_ok(unsigned char n, uint16_t old_pwm)
{
	pwmled_t *led = pwmleds + n;

	if (led->pwm == old_pwm) {
		if (led->probe_steady < PWMLED_PROBE_STEADY_COUNT)
			led->probe_steady++;
	} else {
		led->probe_steady = 0;
	}

	if (led->probe_steady < PWMLED_PROBE_STEADY_COUNT
		&& old_pwm <= led->pwm)
		return 0;

	// probed OK
	led->mode_pwm[led->mode - 1] = led->pwm;
	led->err_sums[led->mode - 1] = 0;

	// next mode to probe?
	if (led->mode < N_PWMLED_MODES) {
		led->probe_steady = 0;
		led->err_sum = 0;

		led->mode++;
		led->target = adc_vals[n*N_PWMLED_MODES+led->mode-1];

		return 0;
	} else {
		unsigned char i;

		led->state = ST_OFF;
		pwm_off(n);

		log_byte(0xF0);
		log_byte(n);
		log_word(jiffies);

		for (i = 0; i < N_PWMLED_MODES; i++)
			log_word(led->mode_pwm[i]);

		log_flush();

		pattern_reload();

		return 1;
	}
}

static inline void pwmled_err(unsigned char n)
{
	pwmleds[n].state = ST_DISABLED;
	pwm_off(n);

	log_byte(0xF1);
	log_byte(n);
	log_word(jiffies);
	log_flush();

	switch (n) {
	case 0: err_flags.err_pwmled0 = 1; break;
	case 1: err_flags.err_pwmled1 = 1; break;
	case 2: err_flags.err_pwmled2 = 1; break;
	}
}


void pwmled_adc(unsigned char n, uint16_t adcval)
{
	pwmled_t *led = pwmleds + n;
	uint16_t old_pwm;
	int32_t sum;
	unsigned char shift;

	if (!ST_IS_ON(led->state))
		return;

	if (led->state == ST_ON && led->mode_changed) {
		led->mode_changed--;
		return;
	}
	// FIXME: test for maximum adcval value (adc_max[n])

	old_pwm = led->pwm;

	// shift = led->state == ST_PROBING ? 3 : 8;
	shift = 3;

	sum = ((int32_t)led->pwm << shift)
		+ led->err_sum + led->target - adcval;

	if (sum < 0)
		sum = 0;

	led->pwm = sum >> shift;
	sum -= led->pwm << shift;
	led->err_sum = sum;

	if (led->pwm >= PWM_MAX
		|| (n == 1 && led->pwm > PWM_MAX/2 && adcval < 0x08)) {
		pwmled_err(n);
		return;
	}

	if (led->state == ST_PROBING)
		if (pwmled_probed_ok(n, old_pwm))
			return;

	if (led->modes_not_yet_stable) {
		if (!--led->modes_not_yet_stable) {
			// reached stability, copy mode 2 to mode 3 (-1)
			led->mode_pwm[0] = led->pwm;
			led->mode_pwm[2] = led->pwm;
			led->err_sums[0] = 0;
			led->err_sums[2] = 0;
		}
	}

	if (led->pwm == old_pwm)
		return;

	pwm_set(n, led->pwm);
}