#ifndef GPIO_H__
#define GPIO_H__

#include "common.h"
#include "rcc.h"

#include <stdint.h>

/*
 * Possible GPIO ports.
 */
typedef enum {
  GPIO_PORT_A = 0,
  GPIO_PORT_B = 1,
  GPIO_PORT_C = 2,
  GPIO_PORT_D = 3
} gpio_port_number_t;

/*
 * Structure defining the layout of the layout of the GPIO registers on the
 * stm32l432 development board.
 */
typedef struct GPIO_PORT_STR {
  __IO uint32_t mode_r;   /* Mode register */
  __IO uint32_t otype_r;
  __IO uint32_t ospeed_r;
  __IO uint32_t pupd_r;
  __IO uint32_t id_r;
  __IO uint32_t output_r;
  __IO uint32_t bsr_r;
  __IO uint32_t lck_r;
  __IO uint32_t af_rl;
  __IO uint32_t af_rh;
} PACKED gpio_port_t;

/*
 * Enum defining the PINs in a GPIO port. Each port has 16 pins to use in
 * the stm32l432.
 */
typedef enum GPIO_PIN_ENUM {
  PIN_0 = 0,
  PIN_1 = 1,
  PIN_2 = 2,
  PIN_3 = 3,
  PIN_4 = 4,
  PIN_5 = 5,
  PIN_6 = 6,
  PIN_7 = 7,
  PIN_8 = 8,
  PIN_9 = 9,
  PIN_10 = 10,
  PIN_11 = 11,
  PIN_12 = 12,
  PIN_13 = 13,
  PIN_14 = 14,
  PIN_15 = 15
} gpio_pin_t;

/* Alternate function number. */
typedef enum {
  AFN_0 = 0,
  AFN_1 = 1,
  AFN_2 = 2,
  AFN_3 = 3,
  AFN_4 = 4,
  AFN_5 = 5,
  AFN_6 = 6,
  AFN_7 = 7,
  AFN_8 = 8,
  AFN_9 = 9,
  AFN_10 = 10,
  AFN_11 = 11,
  AFN_12 = 12,
  AFN_13 = 13,
  AFN_14 = 14,
  AFN_15 = 15
} alternate_function_t;

/*
 * Enum defining the pin modes that are possible.
 */
typedef enum {
  MODE_INPUT = 0,
  MODE_OUTPUT = 1,
  MODE_ALTERNATE = 2,
  MODE_ANALOG = 3
} gpio_pin_mode_t;

/*
 * Enum defining the pin speeds that are possible.
 */
typedef enum {
  SPEED_2MHZ = 0,
  SPEED_10MHZ = 1,
  SPEED_50MHZ = 3,
} speed_t;

/*
 * Structure defining an OUTPUT pin. Structurally equivalent to the input pin,
 * but can be used in a slightly type-safe manner.
 */
typedef struct {
  __IO gpio_port_t* gpio_port;
  gpio_pin_t pin;
} gpio_output_pin_t;

/*
 * Sets the mode on a GPIO pin.
 *
 * gpio_port: the gpio port to use.
 * pin: the pin number to set.
 * pin_mode: the mode to set the pin to.
 */
void set_gpio_pin_mode(
    __IO gpio_port_t* gpio_port, gpio_pin_t pin, gpio_pin_mode_t pin_mode);

/*
 * Sets the given GPIO pin to be an output pin. Returns an output_pin struct
 * corresponding to
 */
gpio_output_pin_t set_gpio_pin_output(
    __IO gpio_port_t* gpio_port, gpio_pin_t pin);

/*
 * Sets an output pin on or off.
 *
 * pin: the pin to toggle.
 * onoff: 0 for off, non-zero of on.
 */
void set_gpio_output_pin(gpio_output_pin_t pin, bool onoff);

#define pin_on(p) set_gpio_output_pin(p, 1)

#define pin_off(p) set_gpio_output_pin(p, 0)

/*
 * Enables a GPIO port and returns a reference to the register definition
 * of that GPIO port.
 */
__IO gpio_port_t* enable_gpio(gpio_port_number_t number);

/* Sets the alternate function for a GPIO pin. */
void set_gpio_alternate_function(
    __IO gpio_port_t* port, gpio_pin_t gpio_pin, alternate_function_t afn);

#endif /* GPIO_H__ */