length := fn(ptr: ^u8): int {
	len := 0
	loop if *(ptr + len) == 0 break else len += 1
	return len
}

display_int := fn(num: int, p: ^u8): ^u8 {
	i := 0
	if num == 0 {
		*p = 48
		return p
	}
	loop if num == 0 break else {
		*(p + i) = num % 10 + 48
		num /= 10
		i += 1
	}
	@inline(reverse, p);
	*(p + i) = 0
	return p
}

reverse := fn(s: ^u8): void {
	//reverse a string, don't remove digits
	len := 0
	loop if *(s + len) == 0 break else len += 1
	i := 0
	j := len - 1
	temp := 0
	loop if i >= j break else {
		temp = *(s + i);
		*(s + i) = *(s + j);
		*(s + j) = temp
		i += 1
		j -= 1
	}
	return
}