#pragma once 

#ifndef GPIO_DRIVER_H
#define GPIO_DRIVER_H

#include <stdint.h>

#define RCC_BASE    0x40021000U
#define RCC_ADDRESS 0x18U
#define RCC_APB2ENR (*(volatile uint32_t*)(RCC_BASE + RCC_ADDRESS))


#define GPIOB_BASE       0x40010C00U
#define GPIOB_CRL_OFFSET 0x00000000U
#define GPIOB_CRL        (*(volatile uint32_t*)(GPIOB_BASE + GPIOB_CRL_OFFSET))

#define GPIOB_BSRR_OFFSET 0x10U
#define GPIOB_BSRR        (*(volatile uint32_t *)(GPIOB_BASE + GPIOB_BSRR_OFFSET))

void gpio_init();
void gpio_write();
void gpio_toggle();

#endif

void setup() {
  gpio_init();
}

void loop() {
  gpio_toggle();
}

void gpio_init() {

  RCC_APB2ENR |= (1 << 3);

  GPIOB_CRL &= ~(0xF << 0);
  GPIOB_CRL |=  (0x2 << 0);
}

void gpio_write() {}

void gpio_toggle() {

    GPIOB_BSRR = (1U << 0);
}