use core::fmt::{self, Write};

const UART: usize = 0x1000_0000;
const UART_STATUS: usize = UART + 0x5;
const MASK: u8 = 1 << 5;

pub struct Uart;

impl Uart {
    pub fn write_byte(src: u8) {
        unsafe {
            let status = UART_STATUS as *mut u8;
            let reg = UART as *mut u8;

            while core::ptr::read_volatile(status) & MASK == 0 {}

            core::ptr::write_volatile(reg, src);
        }
    }

    pub fn print(args: fmt::Arguments) {
        Uart.write_fmt(args).ok();
    }
}

impl Write for Uart {
    fn write_str(&mut self, s: &str) -> core::fmt::Result {
        for byte in s.as_bytes() {
            Self::write_byte(*byte);
        }
        Ok(())
    }
}

#[macro_export]
macro_rules! uprint {
    ($($arg:tt)*) => {{
        $crate::uart::Uart::print(core::format_args!($($arg)*));
    }};
}

#[macro_export]
macro_rules! uprintln {
    () => {
        $crate::uprint!("\n")
    };
    ($($arg:tt)*) => {{
        uprint!("{}\n", core::format_args!($($arg)*));
    }}
}