#include <stdint.h>
#include <stdbool.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
//---------------------------------------------------------------------------------------------------------
int main(void) {
  // enable clocks for GPIOA, GPIOB, GPIOC, GPIOD
  RCC->APB2ENR |= RCC_APB2ENR_IOPAEN | RCC_APB2ENR_IOPBEN | RCC_APB2ENR_IOPCEN | RCC_APB2ENR_IOPDEN;

  // configure all pins on GPIOA as output (MODE = 0b11, CNF = 0b00)
  GPIOA->CRL = 0x33333333;  // PA0–PA7
  GPIOA->CRH = 0x33333333;  // PA8–PA15

  // configure all pins on GPIOB as output (MODE = 0b11, CNF = 0b00)
  GPIOB->CRL = 0x33333333;  // PB0–PB7
  GPIOB->CRH = 0x33333333;  // PB8–PB15

  // disable JTAG, keep SWD enabled (free PA15, PB3, PB4)
  // AFIO->MAPR |= AFIO_MAPR_SWJ_CFG_JTAGDISABLE;

  // disable both JTAG and SWD (NOT recommended)
  // AFIO->MAPR |= AFIO_MAPR_SWJ_CFG_DISABLE;

  // configure all pins on GPIOC as output (MODE = 0b11, CNF = 0b00)
  GPIOC->CRL = 0x33333333;  // PC0–PC7
  GPIOC->CRH = 0x33333333;  // PC8–PC15
	
  // RCC->APB2ENR |= RCC_APB2ENR_AFIOEN;

  // configure PD0–PD1 as output (MODE = 0b11, CNF = 0b00)
  // GPIOD->CRL &= ~((0xF << (0 * 4)) | (0xF << (1 * 4)));
  // GPIOD->CRL |= ((0x3 << (0 * 4)) | (0x3 << (1 * 4)));

  while (1) {
    GPIOA->ODR = 0xFFFF;  // all high
    GPIOB->ODR = 0xFFFF;
    GPIOC->ODR = 0xFFFF;
    // GPIOD->ODR = 0xFFFF;

    for (volatile int i = 0; i < 100000; i++);

    GPIOA->ODR = 0x0000;  // all low
    GPIOB->ODR = 0x0000;
    GPIOC->ODR = 0x0000;
    // GPIOD->ODR = 0x0000;

    for (volatile int i = 0; i < 100000; i++);
  }
}