[cpu] add Default implementations for a bunch of stuff in cpu

Author: hawkw

cpu/src/x86_all/interrupts/idt/gate32.rs

@@ -24,7 +24,7 @@ extern {
 /// Based on [code](http://wiki.osdev.org/Interrupt_Descriptor_Table#Structure)
 /// from the OS Dev Wiki.
 #[repr(C, packed)]
-#[derive(Copy,Clone)]
+#[derive(Copy,Clone, Default)]
 pub struct Gate { /// bits 0 - 15 of the offset
                  pub offset_lower: u16
                , /// code segment selector (GDT or LDT)

cpu/src/x86_all/interrupts/idt/gate64.rs

@@ -11,13 +11,7 @@ use ::segment;
 use super::{Handler, GateFlags};
 
 use core::{convert, mem};
-
-extern {
-    /// Offset of the 64-bit GDT main code segment.
-    /// Exported by `boot.asm`
-    #[link_name = "gdt64_offset"]
-    static GDT_OFFSET: u16;
-}
+use core::default::Default;
 
 impl GateFlags {
 
@@ -38,6 +32,7 @@ impl GateFlags {
 
 }
 
+
 /// An IDT entry is called a gate.
 ///
 /// Based on [code](http://wiki.osdev.org/Interrupt_Descriptor_Table#Structure)
@@ -47,7 +42,7 @@ impl GateFlags {
 /// Gate-Descriptor Types" in the _Intel® 64 and IA-32 Architectures
 /// Software Developer’s Manual_
 #[repr(C, packed)]
-#[derive(Copy,Clone)]
+#[derive(Copy, Clone, Default)]
 pub struct Gate { /// bits 0 - 15 of the offset
                    pub offset_lower: u16
                  , /// code segment selector (GDT or LDT)
@@ -101,14 +96,10 @@ impl convert::From<Handler> for Gate {
                 let (low, mid, high): (u16, u16, u32) = mem::transmute(handler);
 
             Gate { offset_lower: low
-                 , selector: segment::Selector::from_raw(GDT_OFFSET)
-                 , _zero: 0
-                 // Bit 7 is the present bit
-                 // Bits 4-0 indicate this is an interrupt gate
                  , flags: GateFlags::new_interrupt()
                  , offset_mid: mid
                  , offset_upper: high
-                 , _reserved: 0
+                 , ..Default::default()
                  }
         }
     }
@@ -130,14 +121,10 @@ impl convert::From<*const u8> for Gate {
             let (low, mid, high): (u16, u16, u32) = mem::transmute(handler);
 
             Gate { offset_lower: low
-                 , selector: segment::Selector::from_raw(GDT_OFFSET)
-                 , _zero: 0
-                 // Bit 7 is the present bit
-                 // Bits 4-0 indicate this is an interrupt gate
                  , flags: GateFlags::new_interrupt()
                  , offset_mid: mid
                  , offset_upper: high
-                 , _reserved: 0
+                 , ..Default::default()
                  }
         }
     }

cpu/src/x86_all/interrupts/idt/mod.rs

@@ -54,7 +54,7 @@ bitflags! {
     ///    - `0111`: 80286 16-bit trap gate
     ///    - `1110`: 80386 32-bit interrupt gate
     ///    - `1111`: 80386 32-bit trap gate
-    ///    
+    ///
     /// For more information, refer to the _Intel® 64 and IA-32 Architectures
     /// Software Developer’s Manual_, Vol. 3A, section 6.11, "IDT Descriptors";
     /// and to the OS Dev Wiki
@@ -131,6 +131,11 @@ impl GateFlags {
 
 }
 
+
+impl Default for GateFlags {
+    fn default() -> Self { GateFlags { bits: 0 } }
+}
+
 //==------------------------------------------------------------------------==
 //  IDT implementation
 /// An Interrupt Descriptor Table

cpu/src/x86_all/segment.rs

@@ -20,6 +20,8 @@
 #![warn(missing_docs)]
 
 use core::{fmt, mem};
+use core::default::Default;
+
 use super::PrivilegeLevel;
 
 /// The number of entries in the GDT
@@ -197,6 +199,11 @@ impl Selector {
 
 }
 
+
+impl Default for Selector {
+    #[inline] fn default() -> Self { Selector::from_cs() }
+}
+
 impl fmt::Display for Selector {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         // TODO: this could be much less ugly.
@@ -266,9 +273,11 @@ impl Descriptor {
         self.flags.get_limit_part() & self.limit as u32
     }
 
-
 }
 
+impl Default for Descriptor {
+    #[inline] fn default() -> Self { Descriptor::null() }
+}
 
 bitflags! {
     /// Segment descriptor bitflags field.