1 files changed, 57 insertions, 0 deletions
diff --git a/src/bits32/irq.rs b/src/bits32/irq.rs
new file mode 100644
index 0000000..5d6eb0d
--- /dev/null
+++ b/src/bits32/irq.rs
@@ -0,0 +1,57 @@
+//! Interrupt description and set-up code.
+
+use shared::descriptor::*;
+use shared::paging::VAddr;
+use shared::PrivilegeLevel;
+
+/// An interrupt gate or trap gate descriptor.
+///
+/// See Intel manual 3a for details, specifically section 6.11.
+#[derive(Debug, Copy, Clone)]
+#[repr(C, packed)]
+pub struct IdtEntry {
+    /// Lower 16 bits of ISR.
+    pub offset_lo: u16,
+    /// Segment selector.
+    pub selector: u16,
+    /// This must always be zero.
+    pub reserved: u8,
+    /// flags.
+    pub flags: Flags,
+    /// The upper 16 bits of ISR.
+    pub offset_hi: u16
+}
+
+impl IdtEntry {
+    pub const MISSING: IdtEntry = IdtEntry {
+        offset_lo: 0,
+        selector: 0,
+        reserved: 0,
+        flags: Flags::BLANK,
+        offset_hi: 0
+    };
+
+    /// Create a new IdtEntry pointing at `handler`, which must be a function
+    /// with interrupt calling conventions.  (This must be currently defined in
+    /// assembly language.)  The `gdt_code_selector` value must be the offset of
+    /// code segment entry in the GDT.
+    ///
+    /// The "Present" flag set, which is the most common case.  If you need
+    /// something else, you can construct it manually.
+    pub const fn new(handler: VAddr, gdt_code_selector: u16,
+                     dpl: PrivilegeLevel, block: bool) -> IdtEntry {
+        IdtEntry {
+            offset_lo: ((handler.as_usize() as u32) & 0xFFFF) as u16,
+            offset_hi: ((handler.as_usize() as u32 & 0xFFFF0000) >> 16) as u16,
+            selector: gdt_code_selector,
+            reserved: 0,
+            // Nice bitflags operations don't work in const fn, hence these
+            // ad-hoc methods.
+            flags: Flags::from_priv(dpl)
+                .const_or(FLAGS_TYPE_SYS_NATIVE_INTERRUPT_GATE
+                          .const_mux(FLAGS_TYPE_SYS_NATIVE_TRAP_GATE,
+                                        block))
+                .const_or(FLAGS_PRESENT),
+        }
+    }
+}