Interrupt tables.

We add lookup table for interrupt descriptions containing information
about the CPU exceptions etc.

interrupt.rs

+//! Interrupts.
+
+use core::fmt;
+
+/// x86 External Interrupts (1-16).
+pub static EXCEPTIONS: [InterruptDescription; 21] = [
+    Descriptor::new("Division error", Kind::Fault),
+    Descriptor::new("Debug trap", Kind::Trap),
+    Descriptor::new("Unmaskable interrupt", Kind::Unmaskable),
+    Descriptor::new("Breakpoint", Kind::Trap),
+    Descriptor::new("Overflow", Kind::Trap),
+    Descriptor::new("Out of bound", Kind::Fault),
+    Descriptor::new("Invalid opcode", Kind::Fault),
+    Descriptor::new("Device unavailable", Kind::Fault),
+    Descriptor::new("Double fault", Kind::Fault),
+    Descriptor::new("Coprocessor segment overrun", Kind::Fault),
+    Descriptor::new("Invalid TSS", Kind::Fault),
+    Descriptor::new("Segment not present", Kind::Fault),
+    Descriptor::new("Stack-segment fault", Kind::Fault),
+    Descriptor::new("General protection", Kind::Fault),
+    Descriptor::new("Page fault", Kind::Fault),
+    Descriptor::new("Reserved", Kind::Reserved),
+    Descriptor::new("x87 FPU", Kind::Fault),
+    Descriptor::new("Unaligned memory access", Kind::Fault),
+    Descriptor::new("Machine check", Kind::Abort),
+    Descriptor::new("SIMD floating-point", Kind::Fault),
+    Descriptor::new("SIMD floating-point", Kind::Fault),
+    Descriptor::new("Virtualization violation", Kind::Fault),
+];
+
+/// An interrupt description.
+#[derive(Debug, Copy, Clone)]
+pub struct Descriptor {
+    /// The description of this interrupt.
+    pub desc: &'static str,
+    /// The interrupt type.
+    pub kind: Kind,
+}
+
+impl Descriptor {
+    /// Create a new interrupt description.
+    pub fn new(desc: &'static str, kind: Kind) -> Descriptor {
+        Descriptor {
+            desc: desc,
+            kind: kind,
+        }
+    }
+}
+
+/// The interrupt kind.
+pub enum Kind {
+    /// A fault.
+    ///
+    /// This can have multiple sources, but is often a result of a program error of some sort.
+    Fault,
+    /// A trap.
+    ///
+    /// These are often for debugging purposes.
+    Trap,
+    /// A deliberate abort.
+    Abort,
+    /// An unmaskable interrupt.
+    ///
+    /// This is a forced interrupt which need to be handled immediately.
+    Unmaskable,
+    /// Reserved or deprecated.
+    Reserved,
+}
+
+/// Enable interrupts.
+pub unsafe fn enable() {
+    asm!("sti");
+}
+
+/// Disable interrupts.
+pub unsafe fn disable() {
+    asm!("cli");
+}
+
+/// Fire a software interrupt.
+///
+/// Due to inlining being strictly required, we use a macro.
+#[macro_export]
+macro_rules! interrupt {
+    ($int:expr) => {{
+            asm!("int $0" :: "N" ($int));
+    }};
+}