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

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;                  // EDGE SENSITIVE
    GPIO_PORTF_IBE_R = 0x00;                  // ONE EDGE
    GPIO_PORTF_IEV_R = 0x00;                  // INTERRUPT EVENT FALLING
    GPIO_PORTF_IM_R  |= 0x11;                 // UNMASK INTERRUPT
}

void GPIO_PORT_B_init(void)
{

    SYSCTL_RCGCGPIO_R |= 0x02;                // ENABLE CLOCK FOR GPIOB
    SYSCTL_RCGCUART_R |= 0x02;                // ENABLE CLOCK FOR UART1

    GPIO_PORTB_DEN_R |= 0x03;                 // DIGITAL ENABLE FOR PB0 AND PB1
    GPIO_PORTB_AFSEL_R |= 0x03;               // ENABLE ALTERNATE FUNCTION ON PB0,PB1

    GPIO_PORTB_PCTL_R = (GPIO_PORTB_PCTL_R & 0xFFFFFF00) | 0x00000011; // Set PB0, PB1 for UART

    UART1_CTL_R &= ~0x01;                     // DISABLE UART1 DURING SETUP
    UART1_IBRD_R = 104;                       // Set integer part of baud rate (for 9600 baud at 16 MHz clock)
    UART1_FBRD_R = 11;                        // Set fractional part of baud rate
    UART1_LCRH_R = 0x62;                      // 8-bit, odd parity, 1 stop bit
    UART1_CC_R = 0x00;                        // Use system clock

    UART1_CTL_R |= 0x301;                     // Enable UART1, RX, and TX

}

void UART1_WRITE(char data)
{
    while (UART1_FR_R & 0x20);                // Wait until TX FIFO is not full
    UART1_DR_R = data;                        // Write data to UART data register
}

char UART1_READ(void)
{
    while (UART1_FR_R & 0x10);                // Wait until RX FIFO is not empty
    return (char)UART1_DR_R;                  // Return received data
}

#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
#define SYSTICK_RELOAD_VALUE(us) ((CLOCK_HZ / 1000000) * (us) - 1)  // SYSTICK RELOAD VALUE


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 STATUS_LED(char received_data)
{
    if (received_data == 0xAA)
    {
        GPIO_PORTF_DATA_R |= 0x08;                          // Turn ON Green LED (PF3)
        GPIO_PORTF_DATA_R &= ~0x04;                         // Turn OFF Blue LED (PF2)
    }
    else if (received_data == 0xF0)
    {
        GPIO_PORTF_DATA_R |= 0x04;                         // Turn ON Blue LED (PF2)
        GPIO_PORTF_DATA_R &= ~0x08;                        // Turn OFF Green LED (PF3)
    }
    else
    {
     GPIO_PORTF_DATA_R |= 0x02;                            // RED LED FOR JUNK DATA
    }

}


void GPIOF_interruptHandler(void)                         // Interrupt handler for GPIO Port F
{
    if (GPIO_PORTF_RIS_R & 0x10)                          // SWITCH1 PRESS
    {
        UART1_WRITE(0xF0);                                // WRITE DATA ON UART1
        GPIO_PORTF_ICR_R = 0x10;                          // Clear interrupt flag for PF4
    }

    if (GPIO_PORTF_RIS_R & 0x01)                          // SWITCH2 PRESS
    {
        UART1_WRITE(0xAA);                                // WRITE DATA ON UART1
        GPIO_PORTF_ICR_R = 0x01;                          // Clear interrupt flag for PF0
    }
}


int main(void)                                            // MAIN FUNCTION
{
    GPIO_PORT_F_init();                                   // GPIO INITIALISATION FUNCTION
    GPIO_PORT_B_init();
    systick_setting();                                    // SYSTICK SETUP
    while (1)
    {
      STATUS_LED(UART1_READ());                           // STATUS LED
    }
}