#include <stdbool.h>

typedef enum { portINPUT, portOUTPUT, portOUTPUTOD, portALTOUT, portALTOD, portANALOG } eIOPortMode;

int InitIOPort(GPIO_TypeDef* baseGPIO, uint32_t portNum, eIOPortMode mode)
{
  uint32_t bitPortEn = 0;
  uint32_t bitPortRst = 0;
  uint32_t portTypeVal = 0x0100;    // value bigger than 4-bits combination

  if (baseGPIO == GPIOA)
  {
    bitPortEn = RCC_APB2ENR_IOPAEN;
    bitPortRst = RCC_APB2RSTR_IOPARST;
  }

  if (baseGPIO == GPIOB)
  {
    bitPortEn = RCC_APB2ENR_IOPBEN;
    bitPortRst = RCC_APB2RSTR_IOPBRST;
  }

  if (baseGPIO == GPIOC)
  {
    bitPortEn = RCC_APB2ENR_IOPCEN;
    bitPortRst = RCC_APB2RSTR_IOPCRST;
  }

  if (baseGPIO == GPIOD)
  {
    bitPortEn = RCC_APB2ENR_IOPDEN;
    bitPortRst = RCC_APB2RSTR_IOPDRST;
  }

  if (baseGPIO == GPIOE)
  {
    bitPortEn = RCC_APB2ENR_IOPEEN;
    bitPortRst = RCC_APB2RSTR_IOPERST;
  }

  if ((bitPortEn == 0) || (bitPortRst == 0)     // not selected known GPIO 
    || (portNum > 15))                          // or number of pin to large
    return 0;                                   // return with error

  if (!(RCC->APB2ENR & bitPortEn))              // not enabled ? enable required
  {
    RCC->APB2ENR |= bitPortEn;
    RCC->APB2RSTR |= bitPortRst;
    RCC->APB2RSTR &= ~bitPortRst;
  }

  switch (mode)
  {
    case portINPUT: portTypeVal = 0x08; break;    // 10 00 - Input with pull-up / pull-down, Input mode (reset state)
    case portOUTPUT: portTypeVal = 0x03; break;   // 00 11 - General purpose output push-pull, Output mode, max speed 50 MHz
    case portOUTPUTOD: portTypeVal = 0x07; break; // 01 11 - General purpose output Open-drain, Output mode, max speed 50 MHz
    case portALTOUT: portTypeVal = 0x0B; break;   // 10 11 - Alternate function output Push-pull, Output mode, max speed 50 MHz
    case portALTOD: portTypeVal = 0x0F; break;    // 11 11 - Alternate function output Push-pull, Output mode, max speed 50 MHz
    case portANALOG: portTypeVal = 0x00; break;   // 00 00 - Analog mode, Input mode (reset state)
  }

  if (portTypeVal >= 0x100)   // none as result of "case" block
    return 0;                 // eturn with error

  if (portNum < 8)  // lower 8 pins are in CRL
  {
    baseGPIO->CRL &= ~(0x0f << (portNum * 4));
    baseGPIO->CRL |= portTypeVal << (portNum * 4);
  }
  else              // higher 8 in CRH
  {
    portNum -= 8;   // CRH foe IO 8-15
    baseGPIO->CRH &= ~(0x0f << (portNum * 4));
    baseGPIO->CRH |= portTypeVal << (portNum * 4);
  }

  return 1;
}

void WriteGPIO(GPIO_TypeDef* baseGPIO, uint32_t portNum, bool val)
{
  if (val)
    baseGPIO->ODR |= 1 << portNum;
  else
    baseGPIO->ODR &= ~(1 << portNum);
}

bool ReadGPIO(GPIO_TypeDef* baseGPIO, uint32_t portNum)
{
  return (baseGPIO->IDR & (1 << portNum)) != 0;
}

void ToggleGPIO(GPIO_TypeDef* baseGPIO, uint32_t portNum)
{
  baseGPIO->ODR ^= 1 << portNum;
}