#ifndef GPIO_H_
#define GPIO_H_

#include <stdbool.h>
#include <inttypes.h>

struct gpio {
  volatile uint32_t MODER;    // Port mode register
  volatile uint32_t OTYPER;   // Port output type register
  volatile uint32_t OSPEEDR;  // Port output speed register
  volatile uint32_t PUPDR;    // Port pull-up/pull-down register
  volatile uint32_t IDR;      // Port input data register
  volatile uint32_t ODR;      // Port output data register
  volatile uint32_t BSRR;     // Port bit set/reset register
  volatile uint32_t LCKR;     // Port configuration lock register
  volatile uint32_t AFRL;     // Alternative function low register
  volatile uint32_t AFRH;     // Alternative function high register
};

// AFRH, AFRL registers
#define GPIO_AF_MCO_1 (0b0000)     // Alternative function 0 (AF0)
#define GPIO_AF_USART2_RX (0b0111) // Alternative function 7 (AF7)
#define GPIO_AF_USART2_TX (0b0111) // Alternative function 7 (AF7)

#define GPIO_BASE_ADDR (0x40020000U)
#define GPIO_PORT_OFFSET (0x400U)
#define GPIO(port) ((struct gpio*)(uintptr_t)(GPIO_BASE_ADDR + (GPIO_PORT_OFFSET * port)))

// Create a 8bit number from a port
#define PORT(port) (((port) - 'A') << 8)
// Create a 16bit number from a port and pin
#define PIN(port, num) (PORT(port) | num)
// get the lower byte from a PIN
#define PINNUM(pin) (pin & 0b1111)
// get the upper byte from a PIN
#define PINPORT(pin) (pin >> 8)

typedef enum {
  GPIO_MODE_INPUT,
  GPIO_MODE_OUTPUT,
  GPIO_MODE_AF,
  GPIO_MODE_ANALOG
} GPIO_MODE;

void gpio_set_mode(uint16_t pin, GPIO_MODE mode);
void gpio_set_af(uint16_t pin, uint8_t af);
void gpio_write(uint16_t pin, bool val);

#endif