#![allow(dead_code)]

/// Read a `u8`-sized value from `port`.
pub fn inb(port: u16) -> u8 {
    // The registers for the `in` and `out` instructions are always the
    // same: `a` for value, and `d` for the port address.
    let result: u8;
    unsafe { asm!("inb %dx, %al" : "={al}"(result) : "{dx}"(port) :: "volatile") };
    result
}

/// Write a `u8`-sized `value` to `port`.
pub fn outb(port: u16, value: u8) {
    unsafe { asm!("outb %al, %dx" :: "{dx}"(port), "{al}"(value) :: "volatile") };
}

/// Read a `u16`-sized value from `port`.
pub fn inw(port: u16) -> u16 {
    let result: u16;
    unsafe { asm!("inw %dx, %ax" : "={ax}"(result) : "{dx}"(port) :: "volatile") };
    result
}

/// Write a `u8`-sized `value` to `port`.
pub fn outw(port: u16, value: u16) {
    unsafe { asm!("outw %ax, %dx" :: "{dx}"(port), "{ax}"(value) :: "volatile") };
}

/// Read a `u32`-sized value from `port`.
pub fn inl(port: u16) -> u32 {
    let result: u32;
    unsafe { asm!("inl %dx, %eax" : "={eax}"(result) : "{dx}"(port) :: "volatile") };
    result
}

/// Write a `u32`-sized `value` to `port`.
pub fn outl(port: u16, value: u32) {
    unsafe { asm!("outl %eax, %dx" :: "{dx}"(port), "{eax}"(value) :: "volatile") };
}

/// Halt system
pub fn halt() -> ! {
    unsafe { asm!("cli" : : : : "volatile") };
    loop {
        unsafe { asm!("hlt" : : : : "volatile") };
    }
}

/// wait for an io operation to complete
pub fn io_wait() {
    unsafe {
        asm!("jmp 1f\n\t
                  1:jmp 2f\n\t
                  2:" : : : : "volatile")
    }
}