#include <stdint.h>

#define COM1_BASE_PORT 0x3F8

static inline uint8_t
inb(uint16_t port)
{
	uint8_t data;
	__asm__ ("inb %%dx, %%al" : "=a"(data) : "d"(port));
	return data;
}

static inline void
outb(uint16_t port, uint8_t data)
{
	__asm__ ("outb %%al, %%dx" :: "a"(data), "d"(port));
}

void serial_write_char(char c)
{
	while (1) {
		int line_status = inb(COM1_BASE_PORT + 5);
		if (line_status & 0x20) {
			break;
		}
	}
	outb(COM1_BASE_PORT, c);
}

void
main()
{
	outb(0xE9, 'X');
	serial_write_char('X');
	for (;;) {
		__asm__ ("hlt" :);
	}
}