use core::arch::asm;

const SERIAL_COM1: u16 = 0x3F8;

pub unsafe fn init() {
    outb(SERIAL_COM1 + 1, 0x00); // Disable interrupts  

    outb(SERIAL_COM1 + 3, 0x80);

    outb(SERIAL_COM1, 0x03); // 38400 baud (divisor = 3)
    outb(SERIAL_COM1 + 1, 0x00);

    outb(SERIAL_COM1 + 3, 0x03);

    outb(SERIAL_COM1 + 2, 0xC7);

    outb(SERIAL_COM1 + 4, 0x0B);
}

pub unsafe fn write_byte(byte: u8) {
    while (inb(SERIAL_COM1 + 5) & 0x20) == 0 {}
    outb(SERIAL_COM1, byte);
}

pub unsafe fn write_bytes(bytes: &[u8]) {
    for &byte in bytes {
        write_byte(byte);
    }
}

pub unsafe fn write_str(string: &str) {
    write_bytes(string.as_bytes());
}

unsafe fn outb(port: u16, value: u8) {
    asm!(
        "out dx, al",
        in("dx") port,
        in("al") value,
        options(nostack, nomem, preserves_flags)
    );
}

unsafe fn inb(port: u16) -> u8 {
    let value: u8;

    unsafe {
        asm!("in al, dx",in("dx") port,out("al") value,options(nostack, nomem, preserves_flags));
    }
    
    value
}