#include <stdint.h>

/* --- Periféria címek --- */
#define RCC_BASE    0x40021000UL
#define GPIOA_BASE  0x40010800UL
#define GPIOC_BASE  0x40011000UL

#define REG32(addr) (*(volatile uint32_t *)(addr))

/* --- RCC --- */
#define RCC_APB2ENR REG32(RCC_BASE + 0x18UL)
#define RCC_IOPAEN  (1U << 2)
#define RCC_IOPCEN  (1U << 4)

/* --- GPIOA --- */
#define GPIOA_CRL   REG32(GPIOA_BASE + 0x00UL)
#define GPIOA_IDR   REG32(GPIOA_BASE + 0x08UL)
#define GPIOA_ODR   REG32(GPIOA_BASE + 0x0CUL)

/* --- GPIOC --- */
#define GPIOC_CRH   REG32(GPIOC_BASE + 0x04UL)
#define GPIOC_BSRR  REG32(GPIOC_BASE + 0x10UL)
#define GPIOC_BRR   REG32(GPIOC_BASE + 0x14UL)

void gpio_init(void)
{
    // Órajel engedélyezése GPIOA és GPIOC-hez
    RCC_APB2ENR |= RCC_IOPAEN | RCC_IOPCEN;

    // --- LED PC13-PC15, output push-pull 2MHz ---
    GPIOC_CRH &= ~((0xF << ((13-8)*4)) | (0xF << ((14-8)*4)) | (0xF << ((15-8)*4)));
    GPIOC_CRH |=  ((0x2 << ((13-8)*4)) | (0x2 << ((14-8)*4)) | (0x2 << ((15-8)*4)));

    // --- Gomb PA0-PA2, input pull-up ---
    GPIOA_CRL &= ~((0xF << (0*4)) | (0xF << (1*4)) | (0xF << (2*4)));
    GPIOA_CRL |=  ((0x8 << (0*4)) | (0x8 << (1*4)) | (0x8 << (2*4)));

    // belső pull-up engedélyezése
    GPIOA_ODR |= (1<<0) | (1<<1) | (1<<2);

    // LED alapállapot: kikapcsolva (aktív low)
    GPIOC_BSRR = (1<<13) | (1<<14) | (1<<15);
}

int main(void)
{
    gpio_init();

    while(1)
    {
        // PA0 -> PC13
        if ((GPIOA_IDR & (1<<0)))  // gomb lenyomva
            GPIOC_BRR = (1<<13);    // LED világít
        else
            GPIOC_BSRR = (1<<13);   // LED kikapcsol

        // PA1 -> PC14
        if ((GPIOA_IDR & (1<<1)))  
            GPIOC_BRR = (1<<14);    
        else
            GPIOC_BSRR = (1<<14);   

        // PA2 -> PC15
        if ((GPIOA_IDR & (1<<2)))  
            GPIOC_BRR = (1<<15);    
        else
            GPIOC_BSRR = (1<<15);   
    }
}