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/*
 * 	startup.c
 *
 */
void startup(void) __attribute__((naked)) __attribute__((section (".start_section")) );

//get ready for some defines!
#define SYSCFG_BASE ((volatile unsigned int *) 0x40013800)
#define SYSCFG_EXTICR1 ((volatile unsigned int *) 0x40013808)
#define EXTI_IMR ((volatile unsigned int *) 0x40013C00)
#define EXTI_FTSR ((volatile unsigned int *) 0x40013C0C)
#define EXTI_RTSR ((volatile unsigned int *) 0x40013C08)
#define EXTI_PR ((volatile unsigned int *) 0x40013C14)
#define EXTI3_IRQVEC ((void (**) (void)) 0x2001C064)
#define EXTI2_IRQVEC ((void (**) (void)) 0x2001C060)
#define EXTI1_IRQVEC ((void (**) (void)) 0x2001C05C)
#define EXTI0_IRQVEC ((void (**) (void)) 0x2001C058)
#define NVIC_ISER0  ((volatile unsigned int *) 0xE000E100)
#define NVIC_EXTI3_IRQ_BPOS (1<<9)
#define NVIC_EXTI2_IRQ_BPOS (1<<8)
#define NVIC_EXTI1_IRQ_BPOS (1<<7)
#define NVIC_EXTI0_IRQ_BPOS (1<<6)
#define EXTI3_IRQ_BPOS  (1<<3)
#define EXTI2_IRQ_BPOS  (1<<2)
#define EXTI1_IRQ_BPOS  (1<<1)
#define EXTI0_IRQ_BPOS  (1<<0)

void startup ( void )
{
__asm volatile(
	" LDR R0,=0x2001C000\n"		/* set stack */
	" MOV SP,R0\n"
	" BL main\n"				/* call main */
	"_exit: B .\n"				/* never return */
	) ;
}

typedef struct {
    union {
        struct {
            unsigned short MODER_LOW, MODER_HIGH;
        };
        unsigned int MODER;
    };
    unsigned short OTYPER;
    unsigned short reserved1;
    unsigned int OSPEEDR, PUPDR;
    union {
        unsigned short WHOLE;
        struct {
            unsigned char LOW, HIGH;
        };
        unsigned int reserved2;
    } IDR, ODR;
} *PGPIO;
te
#define GPIO_D ((volatile PGPIO) 0x40020C00)
#define GPIO_E ((volatile PGPIO) 0x40021000)


int count = 0;

void irq0_handler()
{
    GPIO_E->ODR.LOW |= 1<<4;
    GPIO_E->ODR.LOW &= ~(1<<4);
    count++;

    //Kvittera avbrott från EXTI0
    *EXTI_PR |= EXTI0_IRQ_BPOS;
}

void irq1_handler()
{
    GPIO_E->ODR.LOW |= 1<<5;
    GPIO_E->ODR.LOW &= ~(1<<5);
    count++;
    //Kvittera avbrott från EXTI1
    *EXTI_PR |= EXTI1_IRQ_BPOS;
}

void irq2_handler()
{
    GPIO_E->ODR.LOW |= 1<<6;
    GPIO_E->ODR.LOW &= ~(1<<6);
    if(GPIO_D->ODR.HIGH){
        GPIO_D->ODR.HIGH = 0x00;
    } else {
        GPIO_D->ODR.HIGH = 0xFF;
    }

     //Kvittera avbrott från EXTI2
     *EXTI_PR |= EXTI2_IRQ_BPOS;
}


void init_app()
{
    //Sätt upp PD0-7 som visningsenhet
    GPIO_D->MODER_LOW = 0x5555;

    //Sätt upp PD8-15 som diodramp
    GPIO_D->MODER = 0x55555555;

    GPIO_E->MODER_LOW = 0x5500;

    //Koppla PE3 till avbrottslina EXTI3
    *SYSCFG_EXTICR1 &= ~0x0FFF;
    *SYSCFG_EXTICR1 |= 0x0444;

    //Konfigurera EXTI2-0 för att generera avbrott
    *EXTI_IMR |= EXTI2_IRQ_BPOS;
    *EXTI_IMR |= EXTI1_IRQ_BPOS;
    *EXTI_IMR |= EXTI0_IRQ_BPOS;

    //Konfigurera för avbrott på negativ flank
    *EXTI_FTSR |= EXTI2_IRQ_BPOS;
    *EXTI_FTSR |= EXTI1_IRQ_BPOS;
    *EXTI_FTSR |= EXTI0_IRQ_BPOS;

    //inget avbrott på positiv flank;
    *EXTI_RTSR &= ~EXTI2_IRQ_BPOS;
    *EXTI_RTSR &= ~EXTI1_IRQ_BPOS;
    *EXTI_RTSR &= ~EXTI0_IRQ_BPOS;

    //Sätt upp avbrottsvektorer
    *EXTI2_IRQVEC = irq2_handler;
    *EXTI1_IRQVEC = irq1_handler;
    *EXTI0_IRQVEC = irq0_handler;

    //Konfigurera de bitar i NVIC som kontrollerar den avbrottslina som EXTI2-0 kopplats till.
    *NVIC_ISER0 |= NVIC_EXTI2_IRQ_BPOS;
    *NVIC_ISER0 |= NVIC_EXTI1_IRQ_BPOS;
    *NVIC_ISER0 |= NVIC_EXTI0_IRQ_BPOS;
}

void main(void)
{
    init_app();
    while(1){
        GPIO_D->ODR.LOW = count;
    }
}