#include <stdint.h>
#include <stdbool.h>
#include "tm4c123gh6pm.h"

void Systick_Handler(void);
void systickInit(void);

int main(void)
{
    SYSCTL_RCGC2_R |= 0x00000020;       /* enable clock to GPIOF */
    GPIO_PORTF_LOCK_R = 0x4C4F434B;     /* unlock commit register */
    GPIO_PORTF_CR_R = 0x1F;             /* make PORTF0 configurable */
    GPIO_PORTF_DEN_R = 0x1E;            /* set PORTF pins 4 pin */
    GPIO_PORTF_DIR_R = 0x0E;            /* set PORTF4 pin as input user switch pin */
    GPIO_PORTF_PUR_R = 0x10;            /* PORTF4 is pulled up */

    GPIO_PORTF_IS_R = (~(1<<4));
    GPIO_PORTF_IBE_R = (~(1<<4));
    GPIO_PORTF_IEV_R = (~(1<<4));
    GPIO_PORTF_IM_R  = (1<<4);
    NVIC_EN0_R |= (1<<30);


   while(1)
   {

      }


}

void systickInit()
{
    NVIC_ST_CURRENT_R = 0;
    NVIC_ST_CTRL_R = 0x07;
    NVIC_ST_RELOAD_R = 8000000;
}

void Systick_Handler()
{
    systickInit();
       if (GPIO_PORTF_DATA_R & 0x04) {
           GPIO_PORTF_DATA_R &= ~0x04;

       }
       else {
           GPIO_PORTF_DATA_R |= 0x04;
       }
       systickInit();
    }