#![feature(asm_experimental_arch)]
#![no_std]
#![no_main]

use core::arch::asm;
use core::ptr::{read_volatile, write_volatile};

const DDRB: *mut u8 = 0x24 as *mut u8;
const PORTB: *mut u8 = 0x25 as *mut u8;

const CPU_SPEED: u32 = 16_000_000;

#[no_mangle]
pub extern "C" fn main() -> ! {
    unsafe { write_volatile(DDRB, 0b11111111) };

    loop {
        unsafe { write_volatile(PORTB, 0b00000000) };
        sleep(1);
        unsafe { write_volatile(PORTB, 0b00100000) };
        sleep(1);
    }
}

fn sleep(time: u32) {
    for _ in 0..(CPU_SPEED / 10 * time) {
        unsafe { asm!("nop") }
    }
}

#[panic_handler]
fn panic(_info: &::core::panic::PanicInfo) -> ! {
    loop {}
}