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


// Global Variables
volatile int duty = 50; // Initial duty cycle
volatile bool buttonPressed = false; // Track button state
volatile uint32_t pressDuration = 0; // Track how long the button is pressed
const long int PWM_PERIOD = 1000; // Period for 100kHz in microseconds (10ms)
#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 COUNT_FLAG (1 << 16) // Bit 16 of CSR automatically set to 1
#define ENABLE (1 << 0) // Bit 0 of CSR to enable the timer
#define CLKINT (1 << 2) // Bit 2 of CSR to specify CPU clock
#define CLOCK_HZ 16000000 // Clock frequency of EK-TM4C123GXL
#define INTEN (1 << 1) // Bit 1 of CSR to enable interrupt
#define SYSTICK_RELOAD_VALUE(us) ((CLOCK_HZ / 1000000) * (us) - 1) // SysTick reload value in microseconds based on clock frequency

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, PF3 as output
    GPIO_PORTF_PUR_R = 0x11; // PORTF PF0 and PF4 is pulled up

    NVIC_EN0_R |= 1 << 30; // Enable interrupt for PORTF
    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) {
    STRELOAD = SYSTICK_RELOAD_VALUE(PWM_PERIOD/100);            // Set reload value for 10 µs intervals (100 kHz)
    STCTRL  |= (CLKINT | ENABLE | INTEN);                       // Set internal clock, enable the timer
    STCURRENT = 0;                                              // Clear STCURRENT 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 SystickHandler(void)
{                                   // SysTick interrupt handler
    ontime++;
    if (ontime < duty)
    {
        GPIO_PORTF_DATA_R |= 0x02;  // LED should be ON
    }
    else
    {
        GPIO_PORTF_DATA_R &= ~0x02; // LED should be OFF
    }

    if (ontime >= 100)
    {
        ontime = 0;                 // Reset counter after one period
    }
// Handle button press duration measurement
    if (buttonPressed) {
        pressDuration++;
    }

} 

void GPIOF_interruptHandler(void) {
    // Check if PF0 (SW1) is pressed (interrupt)
    //long int i = 0;
    //for (i=0; i < 100000 ; i++){ }
    if (!(GPIO_PORTF_DATA_R & 0x01))
    {
        if (!buttonPressed) { // If button was not already pressed
            buttonPressed = true;
            pressDuration = 0; // Reset press duration
        }
    } else { // Button released
        if (buttonPressed) { // Only if button was previously pressed
            buttonPressed = false;

            // Determine press duration
            if (pressDuration > 100) {  // Long press (>1 sec if using 10 ms ticks)
                    duty -= 5;  // Decrease duty cycle
                                    if (duty < 0)
                                        {duty = 0;
                                        // Ensure duty cycle doesn't gor below 0%

                    }
            } else if (pressDuration < 100){  // Short press
                duty += 5;  // decrease duty cycle
                               if (duty > 100)
                                   {duty = 100;
                                   // Ensure duty cycle doesn't exceed 100%
                    }
            }
        }

        // Clear the interrupt flag for PF0 (Switch 1)
        GPIO_PORTF_ICR_R = 0x01;  // Clear interrupt flag
    }
}

int main(void) {
    GPIO_PORT_F_init(); // GPIO initialization function
    systick_setting(); // SysTick setup

    while (1) {
        // Main loop does nothing; everything is handled in interrupts
    }
}