#include <avr/io.h>		//I-O registers
  #include <avr/interrupt.h>
  #include <util/delay.h>		//_delay_ms
  
  #define NB_TICK 104		//1563
  #define CPU_FREQ 16000000L 	//Frequence du CPU
  #define QUANTUM_ms 10
  
  #define SAVE_CONTEXT()  \
  asm volatile ( \
  "push	r0				\n\t" \
  "in		r0, __SREG__		\n\t" \
  "cli					\n\t" \
  "push	r0				\n\t" \
  "push	r1				\n\t" \
  "clr	r1				\n\t" \
  "push	r2				\n\t" \
  "push	r3				\n\t" \
  "push	r4				\n\t" \
  "push	r5				\n\t" \
  "push	r6				\n\t" \
  "push	r7				\n\t" \
  "push	r8				\n\t" \
  "push	r9				\n\t" \
  "push	r10				\n\t" \
  "push	r11				\n\t" \
  "push	r12				\n\t" \
  "push	r13				\n\t" \
  "push	r14				\n\t" \
  "push	r15				\n\t" \
  "push	r16				\n\t" \
  "push	r17				\n\t" \
  "push	r18				\n\t" \
  "push	r19				\n\t" \
  "push	r20				\n\t" \
  "push	r21				\n\t" \
  "push	r22				\n\t" \
  "push	r23				\n\t" \
  "push	r24				\n\t" \
  "push	r25				\n\t" \
  "push	r26				\n\t" \
  "push	r27				\n\t" \
  "push	r28				\n\t" \
  "push	r29				\n\t" \
  "push	r30				\n\t" \
  "push	r31				\n\t" \
  );
  
  #define RESTORE_CONTEXT() \
  asm volatile ( \
  "pop	r31				\n\t" \
  "pop	r30				\n\t" \
  "pop	r29				\n\t" \
  "pop	r28				\n\t" \
  "pop	r27				\n\t" \
  "pop	r26				\n\t" \
  "pop	r25				\n\t" \
  "pop	r24				\n\t" \
  "pop	r23				\n\t" \
  "pop	r22				\n\t" \
  "pop	r21				\n\t" \
  "pop	r20				\n\t" \
  "pop	r19				\n\t" \
  "pop	r18				\n\t" \
  "pop	r17				\n\t" \
  "pop	r16				\n\t" \
  "pop	r15				\n\t" \
  "pop	r14				\n\t" \
  "pop	r13				\n\t" \
  "pop	r12				\n\t" \
  "pop	r11				\n\t" \
  "pop	r10				\n\t" \
  "pop	r9				\n\t" \
  "pop	r8				\n\t" \
  "pop	r7				\n\t" \
  "pop	r6				\n\t" \
  "pop	r5				\n\t" \
  "pop	r4				\n\t" \
  "pop	r3				\n\t" \
  "pop	r2				\n\t" \
  "pop	r1				\n\t" \
  "pop	r0				\n\t" \
  "out 		__SREG__, r0		\n\t" \
  "pop	r0				\n\t" \
  );
  
  /*
  protocole de communication choisi
  16u2 vers 328p (led) -> 1 bit = état d'une led
  
  328p vers 16u2 (boutons + joysticks) -> enfonction du bit 7 :
  à 0 : boutons puis un bit = état du bouton
  à 1 : joysticks -> bit 6 = direction x ou y puis le reste, la valeur sur 6 bits
  */
  
  struct task{
  	uint16_t sp_vise;
  	uint8_t state;
  };
  
  uint8_t cpt = 0;
  uint8_t premier_lancement = 0;

  struct task lecture_boutons = {0x300, 0};

  struct task lecture_joystick = {0x0500, 0};

  struct task affiche_led = {0x0700, 0};

  
  
  
  
  
  
  
  
  
  
  //debug
  void init_debug(void)//permet de detecter un reboot
  {
  	DDRB |= 0x1F;
  	PORTB |= 0xFF;
  	_delay_ms(300);
  	PORTB &= 0x00;
  }
  
  
  
  
  
  
  
  
  
  
  //gestion de la liaison serie
  void init_serial(int speed)
  {
  	UBRR0 = CPU_FREQ/(((unsigned long int)speed)<<4)-1;//Set baud rate
  	UCSR0B = (1<<TXEN0 | 1<<RXEN0);//Enable transmitter & receiver
  	UCSR0C = (1<<UCSZ01 | 1<<UCSZ00);//Set 8 bits character and 1 stop bit
  	UCSR0A &= ~(1 << U2X0);//Set off UART baud doubler
  }
  
  void send_serial(unsigned char c)
  {
  	loop_until_bit_is_set(UCSR0A, UDRE0);
  	UDR0 = c;
  }
  
  unsigned char get_serial(void)
  {
  	loop_until_bit_is_set(UCSR0A, RXC0);
  	return UDR0;
  }
  
  
  
  
  
  
  
  
  
  
  //gestion du convertisseur analogique vers numerique
  void init_ADC(void)
  {
  	ADCSRA |= ((1<<ADPS2)|(1<<ADPS1)|(1<<ADPS0));//Clock prescaler at 128
  	ADMUX |= (1<<REFS0);
  	ADMUX &= ~(1<<REFS1);//Avcc(+5v) as voltage reference
  	ADMUX &= ~(1<<ADLAR);
  	ADCSRB &= ~((1<<ADTS2)|(1<<ADTS1)|(1<<ADTS0));//ADC in free-running mode
  	//ADCSRA |= (1<<ADATE);//Signal source, in this case is the free-running
  	ADCSRA |= (1<<ADEN);//Power up the ADC
  	ADCSRA |= (1<<ADSC);//Start converting
  }
  
  uint16_t ADC_read(uint8_t adcx)
  {
  	ADMUX |= adcx;//ADC selection
  	ADCSRA |= _BV(ADSC);//ADC start conversion
  	while ( (ADCSRA & _BV(ADSC)) );//Wait until the conversion is finished
  	ADMUX &= ~adcx;//ADC deselection
  	return ADC;
  }
  
  
  
  
  
  
  
  
  
  
  //gestion du timer
  void init_timer()
  {
  	TCCR1B |= _BV(WGM12); // CTC mode with value in OCR1A 
  	TCCR1B |= _BV(CS12);  // CS12 = 1; CS11 = 1; CS10 =1 => CLK/1024 prescaler
  	TCCR1B |= _BV(CS10);
  	OCR1A   = NB_TICK;
  	TIMSK1 |= _BV(OCIE1A);
  }
  
  
  
  
  
  
  
  
  
  
  //gestion de l'initialisation des differentes taches
  void init_tasks(void)
  {
  	DDRD |= 0x00;
  	PORTD |= 0xFF;
  	DDRB |= 0b00111111;
  }
  
  
  
  
  
  
  
  
  
  
  //gestion de l'execution des differentes taches
  void task_lecture_boutons(void)
  {
    uint8_t tmp = 0x00;
    uint8_t tmp2;
  	while(1){
  	  tmp2 = 0x00;
  	  if((PIND&(1<<2)) == 0) tmp2 |= 0b00000001;
  	  if((PIND&(1<<3)) == 0) tmp2 |= 0b00000010;
  	  if((PIND&(1<<4)) == 0) tmp2 |= 0b00000100;
  	  if((PIND&(1<<5)) == 0) tmp2 |= 0b00001000;
  	  if((PIND&(1<<6)) == 0) tmp2 |= 0b00010000;
  	  if(tmp2 != tmp) { send_serial(tmp2); tmp = tmp2; }
  	_delay_ms(QUANTUM_ms);
  	}
  }
  
  void task_lecture_joystick(void)
  {
  	uint8_t tmp = ADC_read(0)>>4;//code sur 6 bits (2 bits de descriptions necessaires)
  	uint8_t tmp2 = ADC_read(1)>>4;
  	uint8_t test = 0;
  	uint8_t tmp3;
  	uint8_t tmp4;
  	while(1){
  	tmp3 = ADC_read(0)>>4;
  	tmp4 = ADC_read(1)>>4;
  	if(test == 0 && tmp3 != tmp)
  		{
  		  send_serial(tmp3 | 0b10000000);
  		tmp = tmp3;
  		}
  	else if(test == 1 && tmp4 != tmp2)
  		{
  		  send_serial(tmp4 | 0b11000000);
  		tmp2 = tmp4;
  		}
  	if(test == 0) test = 1; else test = 0;
  	_delay_ms(QUANTUM_ms);
  	}
  }
  
  void task_affiche_led(void)
  {
  	while(1){
  	PORTB = get_serial();
  	_delay_ms(QUANTUM_ms);
  	}
  }
  
  
  
  
  
  
  
  
  
  
  //gestion du contexte
  ISR(TIMER1_COMPA_vect)
  {
  	if(premier_lancement==0)
  	{
  		premier_lancement+= 1;
  		sei();
  		SP = affiche_led.sp_vise;
  		task_affiche_led();
  	}
  	else if(premier_lancement==1)
  	{
  		SAVE_CONTEXT();
  		affiche_led.sp_vise = SP;
  		premier_lancement+=1;
  		sei();
  		SP = lecture_joystick.sp_vise;
  		task_lecture_joystick();
  	}
  	else if(premier_lancement==2)
  	{
  		SAVE_CONTEXT();
  		lecture_joystick.sp_vise = SP;
  		premier_lancement+=1;
  		sei();
          	SP = lecture_boutons.sp_vise;
  		task_lecture_boutons();
  	}
  
  
  	else
  	{
  		if(cpt==0)
  		{
  			SAVE_CONTEXT();
  			lecture_boutons.sp_vise = SP;
  			SP = affiche_led.sp_vise;
  			RESTORE_CONTEXT();
  			cpt++;
  		}
  		else if(cpt==1)
  		{
  			SAVE_CONTEXT();
  			affiche_led.sp_vise = SP;
  			SP = lecture_joystick.sp_vise;
  			RESTORE_CONTEXT();
  			cpt++;
  		}
  		else if(cpt==2)
  		{
  			SAVE_CONTEXT();
  			lecture_joystick.sp_vise = SP;
  			SP = lecture_boutons.sp_vise;
  			RESTORE_CONTEXT();
  			cpt = 0;
  		}
  	}
  	sei();
  }
  
  
  
  
  
  
  
  
  
  
  int main(void)
  {
  	init_debug();//allume toutes les leds au reset
  	init_serial(9600);
  	init_ADC();
  	init_timer();
  
  	init_tasks();
  	sei();
  
  	while(1)
  	{}
  	return 0;
  }