From 74f33c0f44e3991c4fbca42227b9a91d8807ec2e Mon Sep 17 00:00:00 2001
From: Philipp Oppermann <dev@phil-opp.com>
Date: Mon, 23 May 2016 09:02:32 +0200
Subject: [PATCH] Use own Itd entry type

---
 src/interrupts/idt.rs | 92 +++++++++++++++++++++++++++++++++++++++----
 1 file changed, 84 insertions(+), 8 deletions(-)

diff --git a/src/interrupts/idt.rs b/src/interrupts/idt.rs
index b8c68197..93ab6d75 100644
--- a/src/interrupts/idt.rs
+++ b/src/interrupts/idt.rs
@@ -1,22 +1,24 @@
-use x86::irq::IdtEntry;
 
-pub struct Idt([IdtEntry; 16]);
+pub struct Idt([Entry; 16]);
 
 impl Idt {
     pub fn new() -> Idt {
-        Idt([IdtEntry::missing(); 16])
+        Idt([Entry::missing(); 16])
     }
 
-    pub fn set_handler(&mut self, entry: usize, handler: extern fn()->!) {
-        let ptr = handler as usize;
-        self.0[entry] = IdtEntry::interrupt_gate(0x8, ptr as *const _);
+    pub fn set_handler(&mut self, entry: usize, handler: extern "C" fn() -> !) {
+        self.0[entry] = Entry::new(EntryType::InterruptGate, 0x8, handler);
     }
 
-    pub unsafe fn load(&self) {
+    pub fn set_interrupt_stack(&mut self, entry: usize, stack_index: u16) {
+        self.0[entry].options.set_stack_index(stack_index);
+    }
+
+    pub unsafe fn load(&'static self) {
         use x86::dtables::{DescriptorTablePointer, lidt};
         use core::mem::size_of;
 
-        let ptr = DescriptorTablePointer{
+        let ptr = DescriptorTablePointer {
             base: self as *const _ as u64,
             limit: (size_of::<Self>() - 1) as u16,
         };
@@ -24,3 +26,77 @@ impl Idt {
         lidt(&ptr);
     }
 }
+
+use bit_field::BitField;
+
+#[derive(Debug, Clone, Copy)]
+#[repr(C, packed)]
+pub struct Entry {
+    target_low: u16,
+    gdt_selector: u16,
+    options: EntryOptions,
+    target_middle: u16,
+    target_high: u32,
+    reserved: u32,
+}
+
+impl Entry {
+    pub fn missing() -> Entry {
+        Entry {
+            gdt_selector: 0,
+            target_low: 0,
+            target_middle: 0,
+            target_high: 0,
+            options: MISSING,
+            reserved: 0,
+        }
+    }
+
+    pub fn new(ty: EntryType, gdt_selector: u16, handler: extern "C" fn() -> !) -> Entry {
+        let target = handler as u64;
+
+        Entry {
+            gdt_selector: gdt_selector,
+            target_low: target as u16,
+            target_middle: (target >> 16) as u16,
+            target_high: (target >> 32) as u32,
+            options: EntryOptions::new(ty),
+            reserved: 0,
+        }
+    }
+}
+
+const MISSING: EntryOptions = EntryOptions(BitField::new(0));
+
+#[derive(Debug, Clone, Copy)]
+pub struct EntryOptions(BitField<u16>);
+
+impl EntryOptions {
+    pub fn new(ty: EntryType) -> Self {
+        let mut flags = BitField::new(0);
+        match ty {
+            EntryType::InterruptGate => flags.set_range(8..12, 0b1110),
+            EntryType::TrapGate => flags.set_range(8..12, 0b1111),
+        }
+        // set present bit
+        flags.set_bit(15);
+
+        EntryOptions(flags)
+    }
+
+    pub fn set_privilege(&mut self, dpl: u16) {
+        assert!(dpl < 4);
+        self.0.set_range(13..15, dpl);
+    }
+
+    pub fn set_stack_index(&mut self, index: u16) {
+        assert!(index < 8);
+        self.0.set_range(0..3, index);
+    }
+}
+
+#[allow(dead_code)]
+pub enum EntryType {
+    InterruptGate,
+    TrapGate,
+}