#include "stm32f1xx.h"
#include "stm32f1xx_hal.h"

#define PERIPH_BASE           ((uint32_t)0x40000000) /*!< Peripheral base address in the alias region */

/** ===== Macros for AHB and RCC ===== BEGIN ===== */
#define AHBPERIPH_BASE        (PERIPH_BASE + 0x20000)
#define RCC_BASE              (AHBPERIPH_BASE + 0x1000)

/**
typedef struct
{
  __IO uint32_t CR;       // offset = 0x00
  __IO uint32_t CFGR;     // offset = 0x04
  __IO uint32_t CIR;      // offset = 0x08
  __IO uint32_t APB2RSTR; // offset = 0x0c
  __IO uint32_t APB1RSTR; // offset = 0x10
  __IO uint32_t AHBENR;   // offset = 0x14
  __IO uint32_t APB2ENR;  // offset = 0x18
  __IO uint32_t APB1ENR;
  __IO uint32_t BDCR;
  __IO uint32_t CSR;

#ifdef STM32F10X_CL  
  __IO uint32_t AHBRSTR;
  __IO uint32_t CFGR2;
#endif

#if defined (STM32F10X_LD_VL) || defined (STM32F10X_MD_VL) || defined (STM32F10X_HD_VL)   
  uint32_t RESERVED0;
  __IO uint32_t CFGR2;
#endif
} RCC_TypeDef;
*/

#define RCC                 ((RCC_TypeDef *) RCC_BASE)

/** ===== Macros for AHB and RCC ===== END ===== */

/** ===== Macros for APB2 and GPIO C ===== BEGIN ===== */
#define APB2PERIPH_BASE       (PERIPH_BASE + 0x10000)
#define GPIOC_BASE            (APB2PERIPH_BASE + 0x1000)
/**
typedef struct
{
  __IO uint32_t CRL;  // offset = 0x00   (4 bytes)
  __IO uint32_t CRH;  // offset = 0x04
  __IO uint32_t IDR;  // offset = 0x08
  __IO uint32_t ODR;  // offset = 0x0c
  __IO uint32_t BSRR;
  __IO uint32_t BRR;
  __IO uint32_t LCKR;
} GPIO_TypeDef;
*/
#define GPIOC               ((GPIO_TypeDef *) GPIOC_BASE)
#define  RCC_APB2ENR_IOPCEN                  ((uint32_t)0x00000010)  /*!< I/O port C clock enable */
/** ===== Macros for APB2 and GPIO C ===== END ===== */

/** ===== Macros for PIN 13 ===== BEGIN ===== */
#define LED_PIN                                13

#define  GPIO_CRH_MODE13      ((uint32_t)0x00300000)  /*!< MODE13[1:0] bits (Port x mode bits, pin 13) */
#define  GPIO_CRH_MODE13_0    ((uint32_t)0x00100000)  /*!< Bit 0 */
#define  GPIO_CRH_MODE13_1    ((uint32_t)0x00200000)  /*!< Bit 1 */

#define  GPIO_CRH_CNF13       ((uint32_t)0x00C00000)  /*!< CNF13[1:0] bits (Port x configuration bits, pin 13) */
#define  GPIO_CRH_CNF13_0     ((uint32_t)0x00400000)  /*!< Bit 0 */
#define  GPIO_CRH_CNF13_1     ((uint32_t)0x00800000)  /*!< Bit 1 */
/** ===== Macros for PIN 13 ===== END ===== */


void SysTick_Handler(void);

int main(void)
{
  SysTick_Config(SystemCoreClock / 1000);

  // Enable GPIOC clock
  RCC->APB2ENR |= RCC_APB2ENR_IOPCEN;

  // Configure GPIOC Pin 13 as output
  GPIOC->CRH &= ~(GPIO_CRH_MODE13 | GPIO_CRH_CNF13); // Clear mode and config bits
  GPIOC->CRH |= (GPIO_CRH_MODE13_1); // Output mode, max speed 2 MHz
  GPIOC->CRH |= (GPIO_CRH_CNF13_0); // General purpose output push-pull

  while (1)
  {
    // // Toggle LED
    // GPIOC->ODR ^= (1 << LED_PIN);

    // // Simple delay
    // HAL_Delay(500);

    static uint32_t last_check =0 ;
    if(HAL_GetTick() - last_check > 500) {
      // Toggle LED
      GPIOC->ODR ^= (1 << LED_PIN);
      last_check = HAL_GetTick();
    }
  }
}

void SysTick_Handler(void)
{
  // Increment system tick
  HAL_IncTick();
}