#include <avr/io.h>
#include <stdlib.h>
#include <util/delay.h>
#include "config.h"

#ifdef HAS_GRAPHIC_LCD
#include "touch.h"
#include "portbits.h"

#define TOUCH_PORT_X0 PORTF_0
#define TOUCH_PORT_X1 PORTF_1
#define TOUCH_PORT_Y0 PORTF_3
#define TOUCH_PORT_Y1 PORTF_2

#define TOUCH_DDR_X0 	DDRF_0
#define TOUCH_DDR_X1 	DDRF_1
#define TOUCH_DDR_Y0 	DDRF_3
#define TOUCH_DDR_Y1 	DDRF_2

#define TOUCH_CHAN_X0	0
#define TOUCH_CHAN_X1	1
#define TOUCH_CHAN_Y0	3
#define TOUCH_CHAN_Y1	2

#define DELAY_TOUCH 100

// calibration
#define XLO 12
#define XHI	115

#define YLO 16
#define YHI	115


/**
 * ADC initialisieren
 **/

void touch_init(void)
{
	ADMUX = (1 << REFS0);
    ADCSRA = (1 <<ADEN) | (1 << ADSC) | 6;
	while (ADCSRA  & (1 << ADSC));
}

/**
 * ADC Kanal lesen
 * @return 7-bit Wert (0..128) um spätere Überläufe zu verhindern. Könnte man ggf auf 8 oder 9 Bit erhöhen
 **/
unsigned int ADCReadChannel(uint8_t Channel)
{
    ADMUX = (1 << REFS0) | Channel;
    ADCSRA	|= 1 << ADSC;
	while (ADCSRA & (1 << ADSC));        // Wait conversion done
    return ADC >> 3;
}

/**
 * prüft ob der Touch berührt wird. Unmittelbar danach muss X und Y Wert ausgelesen werden
 * @return 0 wenn nicht berührt, > 0 wenn berührt (je höher der Druck um so größer der Wert)
 **/
unsigned int touched(void)
{
	// X-plane auf Masse legen
	TOUCH_DDR_X0	= 1;
	TOUCH_DDR_X1	= 1;
	TOUCH_PORT_X0	= 0;
	TOUCH_PORT_X1	= 0;
	
	// Y-Plane mit Pullup auf +
	TOUCH_DDR_Y0	= 0;
	TOUCH_DDR_Y1	= 0;
	TOUCH_PORT_Y0	= 1;
	TOUCH_PORT_Y1	= 1;

	_delay_us(DELAY_TOUCH);


    return ADCReadChannel(TOUCH_CHAN_Y0) + ADCReadChannel(TOUCH_CHAN_Y1);
}

/**
 * Touch abfragen
 * @return den X Wert in Pixeln
 **/
unsigned int touch_x(void)
{
	int x;
	// X-Plane auf - .. + legen
	TOUCH_DDR_X0	= 1;
	TOUCH_DDR_X1	= 1;
	TOUCH_PORT_X0	= 0;
	TOUCH_PORT_X1	= 1;
	
	// y-plane hochohmig
	TOUCH_DDR_Y0	= 0;
	TOUCH_DDR_Y1	= 0;
	TOUCH_PORT_Y0	= 0;
	TOUCH_PORT_Y1	= 0;
	
	_delay_us(DELAY_TOUCH);
	x = (ADCReadChannel(TOUCH_CHAN_Y0) + ADCReadChannel(TOUCH_CHAN_Y1))  >> 1;
	if (x < XLO) x = XLO;
	if (x > XHI) x = XHI;
	return (x - XLO) * 160 / (XHI - XLO);
}

/**
 * Touch abfragen
 * @return den Y Wert in Pixeln
 **/
unsigned int touch_y(void)
{
	int y;
	// Y-Plane auf - .. + legen
	TOUCH_DDR_Y0	= 1;
	TOUCH_DDR_Y1	= 1;
	TOUCH_PORT_Y0	= 0;
	TOUCH_PORT_Y1	= 1;
	
	// y-plane hochohmig
	TOUCH_DDR_X0	= 0;
	TOUCH_DDR_X1	= 0;
	TOUCH_PORT_X0	= 0;
	TOUCH_PORT_X1	= 0;
	
	_delay_us(DELAY_TOUCH);
	y = (ADCReadChannel(TOUCH_CHAN_X0) + ADCReadChannel(TOUCH_CHAN_X1))  >> 1;

	if (y < YLO) y = YLO;
	if (y > YHI) y = YHI;
	return (y - YLO)*80 / (YHI - YLO);
}

#endif