kern/kernel/io/io.c

#include <lib.h>
#include <stdio.h>
#include <comus/asm.h>

#define PORT 0x3F8
static void serial_out(uint8_t ch)
{
	// wait for output to be free
	while ((inb(PORT + 5) & 0x20) == 0)
		;
	outb(PORT, ch);
}

void fputc(FILE *stream, char c)
{
	(void)stream;

	serial_out(c);
}