/* p2_1.c Toggling LEDs in C using registers by addresses */
/* This program toggles all three LEDs for 0.5 second ON and 0.5 second OFF.*/

/*PF1 - red LED
  PF2 - blue LED
  PF3 - green LED
  They are high active (a '1' turns ON the LED).*/


/* PORTF data register */
#define PORTFDAT (*((volatile unsigned int*)0x400253FC))
/* PORTF data direction register */
#define PORTFDIR (*((volatile unsigned int*)0x40025400))
/* PORTF digital enable register */
#define PORTFDEN (*((volatile unsigned int*)0x4002551C))
/* run mode clock gating register */
#define RCGCGPIO (*((volatile unsigned int*)0x400FE608))
/* coprocessor access control register */
#define SCB_CPAC (*((volatile unsigned int*)0xE000ED88))

void delayMs(int n);     /* function prototype for delay */

int main(void)
{
    /* enable clock to GPIOF at clock gating register */
    RCGCGPIO |= 0x20;
    /* set PORTF pin3-1 as output pins */
    PORTFDIR = 0x0E;	
    /* set PORTF pin3-1 as digital pins */
    PORTFDEN = 0x0E;	

    while(1)
    {
        /* write PORTF to turn on all LEDs */
        PORTFDAT = 0x0E;   
        delayMs(500);
        /* write PORTF to turn off all LEDs */
        PORTFDAT = 0;      
        delayMs(500);
    }
}

/* delay n milliseconds (16 MHz CPU clock) */
void delayMs(int n)
{
    int i, j;
    for(i = 0 ; i < n; i++)
        for(j = 0; j < 3180; j++)
            {}  /* do nothing for 1 ms */
}

/* This function is called by the startup assembly code to perform system specific initialization tasks. */
void SystemInit(void)
{
    /* Grant coprocessor access*/ 
    /* This is required since TM4C123G has a floating point coprocessor */
    SCB_CPAC |= 0x00F00000;
}