#define	SERIAL_BASE 0x3f8
#define UART_LSR 0x5
#define	UART_TX 0x0
#define UART_LSR_TXRDY 0x20

static int putc(char);

static int
inb(int port)
{
	char in;

	__asm __volatile("in %%dx,%0" : "=a" (in) : "d" (port));
	return (in);
}

static void
outb(int port, char o)
{
	__asm __volatile("out %0,%%dx" :: "a" (o), "d" (port));
}

static void
serial_out(char c)
{
	while ((inb(SERIAL_BASE + UART_LSR) & UART_LSR_TXRDY) == 0);
	outb(SERIAL_BASE + UART_TX, c);
}

static int
putc(char c)
{
	serial_out(c);
	return (0);
}

int
main(void)
{
	putc('a');
	putc('\n');
	return (0);
}