Can anyone help me to build Stopwatch with Start/stop, reset, 
pause/resume functionalities?

I have .xsa bitstream from Vivado and want to implement it on 7-segment 
display of Xilinx NEXYS A7 board using C-Code (Xilinx Vitis ISE).

I'm not good with C and have to consider C in this case. The following 
is the code but not really working.

#include "xparameters.h"
#include "xgpio.h"
#include "xtmrctr.h"
#include <unistd.h>
#include "xstatus.h"

#define LED_AN_ADDR 0x40000000  //base address for digit select signals
#define LED_DIS_ADDR 0x40010000 //base address for 7-segment displays
#define SW_ADDR 0x40020000 //base address for 16 switches
#define TMRCTR_DEVICE_ID XPAR_TMRCTR_0_DEVICE_ID //device ID for the 
on-board timer

#define TIMER_FREQ 100000000 // Timer frequency in Hz
#define DISPLAY_PERIOD 100000000/10 // Period for updating the display 
in clock cycles

XGpio Gpio_LedAn;
XGpio Gpio_LedDis;
XGpio Gpio_Sw;
XTmrCtr Timer;

unsigned int hours = 0;  // Time in hours
unsigned int minutes = 0;  // Time in minutes
unsigned int seconds = 0;  // Time in seconds
int state = 0;  // 0 = stopped, 1 = running
void delay(unsigned int delay_count) {
    unsigned int i;
    for (i = 0; i < delay_count; i++);
}


unsigned int get7segData(int num)
{
    static const unsigned int segData[] = {0x3F, 0x06, 0x5B, 0x4F, 0x66, 
0x6D, 0x7D, 0x07, 0x7F, 0x6F};
    if(num >= 0 && num <= 999999) {
        unsigned int result = 0;
        int i;
        for (i = 0; i < 6; i++) {
            result |= segData[num % 10] << (i * 8);
            num /= 10;
        }
        return result;
    } else {
        return 0;
    }
}


void update_display()
{
    // turn off all digit select signals
    XGpio_DiscreteWrite(&Gpio_LedAn, 1, 0x00000000);

    // Display hour tens digit on the leftmost 7-segment display
    XGpio_DiscreteWrite(&Gpio_LedDis, 1, get7segData(hours / 10));
    XGpio_DiscreteWrite(&Gpio_LedAn, 1, 0x1); // turn on digit select 
signal for leftmost display
    delay(0.05 * 1000000);

    // Display hour ones digit on the second leftmost 7-segment display
    XGpio_DiscreteWrite(&Gpio_LedDis, 1, get7segData(hours % 10));
    XGpio_DiscreteWrite(&Gpio_LedAn, 1, 0x2); // turn on digit select 
signal for second leftmost display
    delay(0.05 * 1000000);

    // Display minute tens digit on the third leftmost 7-segment display
    XGpio_DiscreteWrite(&Gpio_LedDis, 1, get7segData(minutes / 10));
    XGpio_DiscreteWrite(&Gpio_LedAn, 1, 0x4); // turn on digit select 
signal for third leftmost display
    delay(0.05 * 1000000);

    // Display minute ones digit on the fourth leftmost 7-segment 
display
    XGpio_DiscreteWrite(&Gpio_LedDis, 1, get7segData(minutes % 10));
    XGpio_DiscreteWrite(&Gpio_LedAn, 1, 0x8); // turn on digit select 
signal for fourth leftmost display
    delay(0.05 * 1000000);

    // Display second tens digit on the fifth leftmost 7-segment display
    XGpio_DiscreteWrite(&Gpio_LedDis, 1, get7segData(seconds / 10));
    XGpio_DiscreteWrite(&Gpio_LedAn, 1, 0x10); // turn on digit select 
signal for fifth leftmost display
    delay(0.05 * 1000000);

    // Display second ones digit on the rightmost 7-segment display
    XGpio_DiscreteWrite(&Gpio_LedDis, 1, get7segData(seconds % 10));
    XGpio_DiscreteWrite(&Gpio_LedAn, 1, 0x20); // turn on digit select 
signal for rightmost display
    delay(0.05 * 1000000);

    // turn off all digit select signals
    XGpio_DiscreteWrite(&Gpio_LedAn, 1, 0x00000000);
}



void timer_interrupt(void *CallbackRef, u8 TmrCtrNumber)
{
    // call the function to display the time on the 7-segment displays
    update_display();
    // increment the time
    seconds++;
    if (seconds == 60) {
        seconds = 0;
        minutes++;
    }
    if (minutes == 60) {
        minutes = 0;
        hours++;
    }
    if (hours == 100) {
        hours = 0;
    }
    // reset the timer counter value
    XTmrCtr_Reset(CallbackRef, TmrCtrNumber);
    // call the function to display the time on the 7-segment displays
    //Read switches
    int switches = XGpio_DiscreteRead(&Gpio_Sw, 1);

    // Check the reset switch
    if (switches & 0x1) {
        // Reset the timer
        hours = 0;
        minutes = 0;
        seconds = 0;
    }

    // Check the start/stop switch
    if (switches & 0x2) {
        // Toggle the state of the stopwatch
        state = !state;
    }

    // If the stopwatch is running, re-enable the timer interrupt
    if (state) {
    XTmrCtr_EnableIntr(&Timer, TmrCtrNumber);
    }
}

int main()
{
    int status;

    // Initialize the digital I/O for the 7-segment displays and digit 
select signals
    status = XGpio_Initialize(&Gpio_LedDis, LED_DIS_ADDR);
    if (status != XST_SUCCESS) return XST_FAILURE;
    status = XGpio_Initialize(&Gpio_LedAn, LED_AN_ADDR);
    if (status != XST_SUCCESS) return XST_FAILURE;

    // Initialize the digital I/O for the 16-bit switches
    status = XGpio_Initialize(&Gpio_Sw, SW_ADDR);
    if (status != XST_SUCCESS) return XST_FAILURE;

    // Initialize the timer
    status = XTmrCtr_Initialize(&Timer, TMRCTR_DEVICE_ID);
    if (status != XST_SUCCESS) return XST_FAILURE;

    // Set the timer to generate an interrupt every 1 second
    XTmrCtr_SetResetValue(&Timer, 0, DISPLAY_PERIOD);
    XTmrCtr_SetOptions(&Timer, 0, XTC_INT_MODE_OPTION | 
XTC_AUTO_RELOAD_OPTION);

    // Register the timer interrupt handler
    XTmrCtr_SetHandler(&Timer, timer_interrupt, &Timer);

    // Enable the global interrupt
    microblaze_enable_interrupts();

    // Start the timer
    XTmrCtr_Start(&Timer, 0);

    return 0;
    }