Luna/kernel/src/arch/x86_64/Serial.cpp

#include "arch/Serial.h"
#include "arch/x86_64/IO.h"

#define COM1 0x3f8

static void serial_wait()
{
    while (!(IO::inb(COM1 + 5) & 0x20)) { asm volatile("pause"); }
}

void Serial::putchar(u8 c)
{
    serial_wait();
    IO::outb(COM1, c);
}