#![no_std]
#![no_main]

use core::panic::PanicInfo;

#[unsafe(no_mangle)]
pub extern "C" fn _start() -> ! {
    welcome_serial();
    halt()
}

fn print_serial(s: &str) {
    let mut bytes = s.bytes();
    while let Some(b) = bytes.next() {
        unsafe {
            core::arch::asm!(
                "out dx, al"
                , in("al") b
            )
        };
    }
}

fn println_serial(s: &str) {
    print_serial(s);
    print_serial("\n");
}

fn welcome_serial() {
    print_serial(ANSI_PINK);
    println_serial("\nWelcome to Bootle OS");
    println_serial("All code GPL licensed and freely available on git.mtgmonkey.net");
    print_serial("Enjoy your time! Press ");
    print_serial(ANSI_RED);
    print_serial("ctrl+a x");
    print_serial(ANSI_PINK);
    println_serial(" to escape Qemu");
    print_serial(ANSI_CLEAR);
}

#[panic_handler]
fn panic(_: &PanicInfo) -> ! {
    print_serial("panicked");
    halt()
}

fn halt() -> ! {
    unsafe { core::arch::asm!("hlt") };
    halt()
}

const ANSI_CLEAR: &str = "\x1b[0m";
const ANSI_RED: &str = "\x1b[31m";
const ANSI_PINK: &str = "\x1b[35m";
const ANSI_GREEN: &str = "\x1b[32m";