/// Kind of exception
#[derive(Clone, Copy, Debug, Eq, PartialEq)]
pub enum Exception {
    /// i.e. currently not servicing an exception
    ThreadMode,
    /// Non-maskable interrupt.
    Nmi,
    /// All class of fault.
    HardFault,
    /// Memory management.
    MemoryManagementFault,
    /// Pre-fetch fault, memory access fault.
    BusFault,
    /// Undefined instruction or illegal state.
    UsageFault,
    /// System service call via SWI instruction
    SVCall,
    /// Pendable request for system service
    PendSV,
    /// System tick timer
    Systick,
    /// An interrupt
    Interrupt(u8),
    // Unreachable variant
    #[doc(hidden)]
    Reserved,
}

impl Exception {
    /// Returns the kind of exception that's currently being serviced
    pub fn current() -> Exception {
        match ::peripheral::scb().icsr.read() as u8 {
            0 => Exception::ThreadMode,
            2 => Exception::Nmi,
            3 => Exception::HardFault,
            4 => Exception::MemoryManagementFault,
            5 => Exception::BusFault,
            6 => Exception::UsageFault,
            11 => Exception::SVCall,
            14 => Exception::PendSV,
            15 => Exception::Systick,
            n if n >= 16 => Exception::Interrupt(n - 16),
            _ => Exception::Reserved,

        }
    }
}