#include <stdint.h>
#include <stdbool.h>
#include "tm4c123gh6pm.h"
// SysTick memory-mapped registers
#define STCTRL *((volatile uint32_t *) 0xE000E010)          // CONTROL AND STATUS
#define STRELOAD *((volatile uint32_t *) 0xE000E014)        // RELOAD VALUE
#define STCURRENT *((volatile uint32_t *) 0xE000E018)       // CURRENT VALUE
#define CLOCK_HZ 16000000       // CLOCK FREQUENCY OF EK-TM4C123GXL
#define SYSTICK_RELOAD_VALUE(us) ((CLOCK_HZ / 1000000) * (us) - 1)  // SYSTICK RELOAD VALUE

void GPIO_PORT_F_init(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  = 0x1F;                 // SET PORTF DIGITAL ENABLE
    GPIO_PORTF_DIR_R  = 0x0E;                 // SET PF0, PF4 as input and PF1, PF2 and PF3 as output
    GPIO_PORTF_PUR_R  = 0x11;                 // PORTF PF0 and PF4 IS PULLED UP

    NVIC_EN0_R |= 1 << 30;
    GPIO_PORTF_IS_R  = 0x00;                 // Make it edge-sensitive
    GPIO_PORTF_IBE_R = 0x00;                 // Trigger on one edge
    GPIO_PORTF_IEV_R = 0x00;                 // Falling edge event
    GPIO_PORTF_IM_R  |= 0x11;                // Unmask interrupts for PF0 and PF4
}
void systick_setting(void)                   // SYSTICK SETUP FUNCTION
{
    STRELOAD = SYSTICK_RELOAD_VALUE(1000);   // RELOAD VALUE FOR 1ms
    STCTRL |= (1 << 0) | (1 << 2);           // Enable SysTick with system clock
    STCURRENT = 0;                           // Clear current value
}

void delay(int us)                           //DEFINING DELAY FUNCTION
{
    STRELOAD = SYSTICK_RELOAD_VALUE(us);     // RELOAD VALUE FOR REQUIRED DELAY
    STCURRENT = 0;                           // Clear STCURRENT
    STCTRL |= (1 << 0) | (1 << 2);           // Enable SysTick
    while ((STCTRL & (1 << 16)) == 0);       // Wait until flag is set
    STCTRL &= 0x0;                           // Stop the timer
}

void GPIOF_interruptHandler(void)            // Interrupt handler for GPIO Port F
{
    delay(200000);                           // DEBOUNCE DELAY
    if (GPIO_PORTF_RIS_R & 0x10)             // CHECK IF SWITCH 1 CAUSED INTERRUPT
    {
        GPIO_PORTF_DATA_R ^= 0x02;           // TOGGLE RED LED
        GPIO_PORTF_ICR_R = 0x10;             // CLEAR INTERRUPT FLAG FOR SWITCH 1
    }

    if (GPIO_PORTF_RIS_R & 0x01)             // CHECK IF SWITCH 2 CAUSED INTERRUPT
    {
        GPIO_PORTF_DATA_R ^= 0x02;           // TOGGLE RED LED
        GPIO_PORTF_ICR_R = 0x01;             // CLEAR INTERRUPT FLAG FOR SWITCH 1
    }
}