From 0ed21fb943b3942cad54b01e13482031dd6e79a4 Mon Sep 17 00:00:00 2001
From: Philipp Oppermann <dev@phil-opp.com>
Date: Wed, 12 Apr 2017 19:24:25 +0200
Subject: [PATCH] Use volatile writes for printing to screen

---
 Cargo.toml        | 1 +
 src/lib.rs        | 1 +
 src/vga_buffer.rs | 7 ++++---
 3 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/Cargo.toml b/Cargo.toml
index eec662f..455d244 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -8,3 +8,4 @@ crate-type = ["staticlib"]
 
 [dependencies]
 rlibc = "1.0"
+volatile = "0.1.0"
diff --git a/src/lib.rs b/src/lib.rs
index 4ed2979..2fa06b5 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -4,6 +4,7 @@
 #![no_std]
 
 extern crate rlibc;
+extern crate volatile;
 
 mod vga_buffer;
 
diff --git a/src/vga_buffer.rs b/src/vga_buffer.rs
index fe07af9..1a76527 100644
--- a/src/vga_buffer.rs
+++ b/src/vga_buffer.rs
@@ -1,4 +1,5 @@
 use core::ptr::Unique;
+use volatile::Volatile;
 
 #[allow(dead_code)]
 #[derive(Debug, Clone, Copy)]
@@ -42,7 +43,7 @@ const BUFFER_HEIGHT: usize = 25;
 const BUFFER_WIDTH: usize = 80;
 
 struct Buffer {
-    chars: [[ScreenChar; BUFFER_WIDTH]; BUFFER_HEIGHT],
+    chars: [[Volatile<ScreenChar>; BUFFER_WIDTH]; BUFFER_HEIGHT],
 }
 
 pub struct Writer {
@@ -64,10 +65,10 @@ impl Writer {
                 let col = self.column_position;
 
                 let color_code = self.color_code;
-                self.buffer().chars[row][col] = ScreenChar {
+                self.buffer().chars[row][col].write(ScreenChar {
                     ascii_character: byte,
                     color_code: color_code,
-                };
+                });
                 self.column_position += 1;
             }
         }