From 16ba0c0686134262131f8cc7017c0b5875572b54 Mon Sep 17 00:00:00 2001
From: Brandon Chinn <brandonchinn178@gmail.com>
Date: Sat, 23 Sep 2023 15:29:31 -0700
Subject: [PATCH 1/2] Add HandlerFuncType trait

---
 Changelog.md          |  4 +++
 src/structures/idt.rs | 57 ++++++++++++++++++++++++++-----------------
 2 files changed, 39 insertions(+), 22 deletions(-)

diff --git a/Changelog.md b/Changelog.md
index 96bb5bd8..947e1d09 100644
--- a/Changelog.md
+++ b/Changelog.md
@@ -1,5 +1,9 @@
 # Unreleased
 
+## New Features
+
+- [Add `HandlerFuncType` trait](https://github.com/rust-osdev/x86_64/pull/439)
+
 # 0.14.11 – 2022-09-15
 
 ## New Features
diff --git a/src/structures/idt.rs b/src/structures/idt.rs
index 75923f37..6eac9404 100644
--- a/src/structures/idt.rs
+++ b/src/structures/idt.rs
@@ -779,34 +779,47 @@ impl<F> Entry<F> {
     }
 }
 
-macro_rules! impl_set_handler_fn {
-    ($h:ty) => {
-        #[cfg(all(feature = "instructions", feature = "abi_x86_interrupt"))]
-        impl Entry<$h> {
-            /// Set the handler function for the IDT entry and sets the present bit.
-            ///
-            /// For the code selector field, this function uses the code segment selector currently
-            /// active in the CPU.
-            ///
-            /// The function returns a mutable reference to the entry's options that allows
-            /// further customization.
-            ///
-            /// This method is only usable with the `abi_x86_interrupt` feature enabled. Without it, the
-            /// unsafe [`Entry::set_handler_addr`] method has to be used instead.
+#[cfg(feature = "instructions")]
+impl<F: HandlerFuncType> Entry<F> {
+    /// Set the handler function for the IDT entry and sets the present bit.
+    ///
+    /// For the code selector field, this function uses the code segment selector currently
+    /// active in the CPU.
+    ///
+    /// The function returns a mutable reference to the entry's options that allows
+    /// further customization.
+    ///
+    /// This method is only usable with the `abi_x86_interrupt` feature enabled. Without it, the
+    /// unsafe [`Entry::set_handler_addr`] method has to be used instead.
+    #[inline]
+    pub fn set_handler_fn(&mut self, handler: F) -> &mut EntryOptions {
+        unsafe { self.set_handler_addr(handler.to_virt_addr()) }
+    }
+}
+
+/// The trait for all function types that can be used as a handler function in `Entry`.
+pub trait HandlerFuncType {
+    /// Get the virtual memory address of the function
+    fn to_virt_addr(self) -> VirtAddr;
+}
+
+macro_rules! impl_handler_func_type {
+    ($f:ty) => {
+        #[cfg(feature = "abi_x86_interrupt")]
+        impl HandlerFuncType for $f {
             #[inline]
-            pub fn set_handler_fn(&mut self, handler: $h) -> &mut EntryOptions {
-                let handler = VirtAddr::new(handler as u64);
-                unsafe { self.set_handler_addr(handler) }
+            fn to_virt_addr(self) -> VirtAddr {
+                VirtAddr::new(self as u64)
             }
         }
     };
 }
 
-impl_set_handler_fn!(HandlerFunc);
-impl_set_handler_fn!(HandlerFuncWithErrCode);
-impl_set_handler_fn!(PageFaultHandlerFunc);
-impl_set_handler_fn!(DivergingHandlerFunc);
-impl_set_handler_fn!(DivergingHandlerFuncWithErrCode);
+impl_handler_func_type!(HandlerFunc);
+impl_handler_func_type!(HandlerFuncWithErrCode);
+impl_handler_func_type!(PageFaultHandlerFunc);
+impl_handler_func_type!(DivergingHandlerFunc);
+impl_handler_func_type!(DivergingHandlerFuncWithErrCode);
 
 /// Represents the options field of an IDT entry.
 #[repr(transparent)]

From faea2730fec1f25b19d8ba318debe68cdeabb917 Mon Sep 17 00:00:00 2001
From: Joe Richey <joerichey@google.com>
Date: Sat, 23 Sep 2023 18:47:52 -0700
Subject: [PATCH 2/2] Update HandlerFuncType documentation

Signed-off-by: Joe Richey <joerichey@google.com>
---
 src/structures/idt.rs | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/structures/idt.rs b/src/structures/idt.rs
index 6eac9404..1f7381b6 100644
--- a/src/structures/idt.rs
+++ b/src/structures/idt.rs
@@ -797,9 +797,9 @@ impl<F: HandlerFuncType> Entry<F> {
     }
 }
 
-/// The trait for all function types that can be used as a handler function in `Entry`.
+/// A common trait for all handler functions usable in [`Entry`].
 pub trait HandlerFuncType {
-    /// Get the virtual memory address of the function
+    /// Get the virtual address of the handler function.
     fn to_virt_addr(self) -> VirtAddr;
 }