How can I implement text input functionality in my custom operating system?

#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>

enum vga_color {
    VGA_COLOR_BLACK = 0,
    VGA_COLOR_BLUE = 1,
    VGA_COLOR_GREEN = 2,
    VGA_COLOR_CYAN = 3,
    VGA_COLOR_RED = 4,
    VGA_COLOR_MAGENTA = 5,
    VGA_COLOR_BROWN = 6,
    VGA_COLOR_LIGHT_GREY = 7,
    VGA_COLOR_DARK_GREY = 8,
    VGA_COLOR_LIGHT_BLUE = 9,
    VGA_COLOR_LIGHT_GREEN = 10,
    VGA_COLOR_LIGHT_CYAN = 11,
    VGA_COLOR_LIGHT_RED = 12,
    VGA_COLOR_LIGHT_MAGENTA = 13,
    VGA_COLOR_LIGHT_BROWN = 14,
    VGA_COLOR_WHITE = 15, };

static inline uint8_t vga_entry_color
 (enum vga_color fg, enum vga_color bg) {
    return fg | bg << 4; }
 
static inline uint16_t vga_entry(unsigned char uc, uint8_t color) {
    return (uint16_t) uc | (uint16_t) color << 8; }
 
size_t strlen(const char* str) {
    size_t len = 0;
    while (str[len])
        len++;
    return len; }
 
static const size_t VGA_WIDTH = 80;
static const size_t VGA_HEIGHT = 25;
 
size_t terminal_row;
size_t terminal_column;
uint8_t terminal_color;
uint16_t* terminal_buffer;

 
void terminal_initialize(void) {
    terminal_row = 0;
    terminal_column = 0;
    terminal_color = vga_entry_color(VGA_COLOR_LIGHT_GREY, VGA_COLOR_BLACK);
    terminal_buffer = (uint16_t*) 0xB8000;
    for (size_t y = 0; y < VGA_HEIGHT; y++) {
        for (size_t x = 0; x < VGA_WIDTH; x++) {
            const size_t index = y * VGA_WIDTH + x;
            terminal_buffer[index] = vga_entry(' ', terminal_color); } } }

void terminal_setcolor(uint8_t color) {
    terminal_color = color; }
 
void terminal_putentryat(char c, uint8_t color, size_t x, size_t y) {
    const size_t index = y * VGA_WIDTH + x;
    terminal_buffer[index] = vga_entry(c, color); }
 
void terminal_scroll(void) {
  for (size_t y = 0; y < VGA_HEIGHT - 1; y++) {
    for (size_t x = 0; x < VGA_WIDTH; x++) {
      const size_t current_index = y * VGA_WIDTH + x;
      const size_t next_line_index = (y + 1) * VGA_WIDTH + x;
      terminal_buffer[current_index] = terminal_buffer[next_line_index]; } }
  const size_t last_row_index = (VGA_HEIGHT - 1) * VGA_WIDTH;
  for (size_t x = 0; x < VGA_WIDTH; x++) {
    terminal_buffer[last_row_index + x] = vga_entry(' ', terminal_color); } }

void terminal_putchar(char c) {
  if (c == '\n') {
    terminal_row++;
    terminal_column = 0; } else {
    terminal_putentryat(c, terminal_color, terminal_column, terminal_row);
    terminal_column++; }

  if (terminal_column >= VGA_WIDTH) {
    terminal_row++;
    terminal_column = 0; }

  if (terminal_row >= VGA_HEIGHT) {
    terminal_scroll();
    terminal_row = VGA_HEIGHT - 1; } }
 
void terminal_write(const char* data, size_t size) {
    for (size_t i = 0; i < size; i++)
        terminal_putchar(data[i]); }
 
void printl(const char* data) {
 terminal_write(data, strlen(data)); }

uint8_t inb(uint16_t port) {
 uint8_t ret;
 asm volatile("inb %1, %0" : "=a"(ret) : "d"(port));
 return ret; }

void outb(uint16_t port, uint8_t data) {
 asm volatile("outb %0, %1" : "=a"(data) : "d"(port)); }

void kernel_main(void) {
    terminal_initialize();
    printl("LainOS\n"); 

while (true) {
    char c = inb(0x60);
    if (c != 0) {
    terminal_putchar(c); } } }