From f94a5a7dcafdcbcd8d43af586a637148515bc86a Mon Sep 17 00:00:00 2001
From: Jeremy Soller <jackpot51@gmail.com>
Date: Fri, 8 Sep 2023 11:14:11 -0600
Subject: [PATCH] 0.4.1: custom mmio read/write functions on x86

---
 Cargo.toml     |   2 +-
 src/io/mmio.rs | 129 +++++++++++++++++++++++++++++++++++++++++++++++--
 2 files changed, 127 insertions(+), 4 deletions(-)

diff --git a/Cargo.toml b/Cargo.toml
index bfe636e522..74b489c5fd 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "redox_syscall"
-version = "0.4.0"
+version = "0.4.1"
 description = "A Rust library to access raw Redox system calls"
 license = "MIT"
 authors = ["Jeremy Soller <jackpot51@gmail.com>"]
diff --git a/src/io/mmio.rs b/src/io/mmio.rs
index 3966ab4546..ef8f603911 100644
--- a/src/io/mmio.rs
+++ b/src/io/mmio.rs
@@ -1,5 +1,6 @@
-use core::ptr::{read_volatile, write_volatile, addr_of, addr_of_mut};
 use core::mem::MaybeUninit;
+use core::ptr;
+#[cfg(not(any(target_arch = "x86", target_arch = "x86_64")))]
 use core::ops::{BitAnd, BitOr, Not};
 
 use super::io::Io;
@@ -32,14 +33,136 @@ impl<T> Mmio<T> {
     }
 }
 
+// Generic implementation (WARNING: requires aligned pointers!)
+#[cfg(not(any(target_arch = "x86", target_arch = "x86_64")))]
 impl<T> Io for Mmio<T> where T: Copy + PartialEq + BitAnd<Output = T> + BitOr<Output = T> + Not<Output = T> {
     type Value = T;
 
     fn read(&self) -> T {
-        unsafe { read_volatile(addr_of!(self.value).cast::<T>()) }
+        unsafe { ptr::read_volatile(ptr::addr_of!(self.value).cast::<T>()) }
     }
 
     fn write(&mut self, value: T) {
-        unsafe { write_volatile(addr_of_mut!(self.value).cast::<T>(), value) };
+        unsafe { ptr::write_volatile(ptr::addr_of_mut!(self.value).cast::<T>(), value) };
+    }
+}
+
+// x86 u8 implementation
+#[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
+impl Io for Mmio<u8> {
+    type Value = u8;
+
+    fn read(&self) -> Self::Value {
+        unsafe {
+            let value: Self::Value;
+            let ptr: *const Self::Value = ptr::addr_of!(self.value).cast::<Self::Value>();
+            core::arch::asm!(
+                "mov {}, [{}]",
+                out(reg_byte) value,
+                in(reg) ptr
+            );
+            value
+        }
+    }
+
+    fn write(&mut self, value: Self::Value) {
+        unsafe {
+            let ptr: *mut Self::Value = ptr::addr_of_mut!(self.value).cast::<Self::Value>();
+            core::arch::asm!(
+                "mov [{}], {}",
+                in(reg) ptr,
+                in(reg_byte) value,
+            );
+        }
+    }
+}
+
+// x86 u16 implementation
+#[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
+impl Io for Mmio<u16> {
+    type Value = u16;
+
+    fn read(&self) -> Self::Value {
+        unsafe {
+            let value: Self::Value;
+            let ptr: *const Self::Value = ptr::addr_of!(self.value).cast::<Self::Value>();
+            core::arch::asm!(
+                "mov {:x}, [{}]",
+                out(reg) value,
+                in(reg) ptr
+            );
+            value
+        }
+    }
+
+    fn write(&mut self, value: Self::Value) {
+        unsafe {
+            let ptr: *mut Self::Value = ptr::addr_of_mut!(self.value).cast::<Self::Value>();
+            core::arch::asm!(
+                "mov [{}], {:x}",
+                in(reg) ptr,
+                in(reg) value,
+            );
+        }
+    }
+}
+
+// x86 u32 implementation
+#[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
+impl Io for Mmio<u32> {
+    type Value = u32;
+
+    fn read(&self) -> Self::Value {
+        unsafe {
+            let value: Self::Value;
+            let ptr: *const Self::Value = ptr::addr_of!(self.value).cast::<Self::Value>();
+            core::arch::asm!(
+                "mov {:e}, [{}]",
+                out(reg) value,
+                in(reg) ptr
+            );
+            value
+        }
+    }
+
+    fn write(&mut self, value: Self::Value) {
+        unsafe {
+            let ptr: *mut Self::Value = ptr::addr_of_mut!(self.value).cast::<Self::Value>();
+            core::arch::asm!(
+                "mov [{}], {:e}",
+                in(reg) ptr,
+                in(reg) value,
+            );
+        }
+    }
+}
+
+// x86 u64 implementation (x86_64 only)
+#[cfg(target_arch = "x86_64")]
+impl Io for Mmio<u64> {
+    type Value = u64;
+
+    fn read(&self) -> Self::Value {
+        unsafe {
+            let value: Self::Value;
+            let ptr: *const Self::Value = ptr::addr_of!(self.value).cast::<Self::Value>();
+            core::arch::asm!(
+                "mov {:r}, [{}]",
+                out(reg) value,
+                in(reg) ptr
+            );
+            value
+        }
+    }
+
+    fn write(&mut self, value: Self::Value) {
+        unsafe {
+            let ptr: *mut Self::Value = ptr::addr_of_mut!(self.value).cast::<Self::Value>();
+            core::arch::asm!(
+                "mov [{}], {:r}",
+                in(reg) ptr,
+                in(reg) value,
+            );
+        }
     }
 }