From 40aed4fa0f24c38118e9d34239bd6c41026f7ccd Mon Sep 17 00:00:00 2001
From: Philipp Oppermann <dev@phil-opp.com>
Date: Wed, 12 Apr 2017 19:32:59 +0200
Subject: [PATCH] Create a static WRITER protected by a spinlock

---
 Cargo.toml        |  1 +
 src/lib.rs        |  7 ++++++-
 src/vga_buffer.rs | 21 +++++++--------------
 3 files changed, 14 insertions(+), 15 deletions(-)

diff --git a/Cargo.toml b/Cargo.toml
index 455d244..b6910f5 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -9,3 +9,4 @@ crate-type = ["staticlib"]
 [dependencies]
 rlibc = "1.0"
 volatile = "0.1.0"
+spin = "0.4.5"
diff --git a/src/lib.rs b/src/lib.rs
index 2fa06b5..3dc67e0 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,10 +1,12 @@
 #![feature(lang_items)]
 #![feature(const_fn)]
+#![feature(const_unique_new)]
 #![feature(unique)]
 #![no_std]
 
 extern crate rlibc;
 extern crate volatile;
+extern crate spin;
 
 mod vga_buffer;
 
@@ -12,7 +14,10 @@ mod vga_buffer;
 pub extern fn rust_main() {
     // ATTENTION: we have a very small stack and no guard page
 
-    vga_buffer::print_something();
+    use core::fmt::Write;
+
+    vga_buffer::WRITER.lock().write_str("Hello again");
+    write!(vga_buffer::WRITER.lock(), ", some numbers: {} {}", 42, 1.337);
 
     loop{}
 }
diff --git a/src/vga_buffer.rs b/src/vga_buffer.rs
index cdfe7ab..ca9187d 100644
--- a/src/vga_buffer.rs
+++ b/src/vga_buffer.rs
@@ -1,7 +1,14 @@
 use core::fmt;
 use core::ptr::Unique;
+use spin::Mutex;
 use volatile::Volatile;
 
+pub static WRITER: Mutex<Writer> = Mutex::new(Writer {
+    column_position: 0,
+    color_code: ColorCode::new(Color::LightGreen, Color::Black),
+    buffer: unsafe { Unique::new_unchecked(0xb8000 as *mut _) },
+});
+
 #[allow(dead_code)]
 #[derive(Debug, Clone, Copy)]
 #[repr(u8)]
@@ -116,17 +123,3 @@ impl fmt::Write for Writer {
         Ok(())
     }
 }
-
-
-pub fn print_something() {
-    use core::fmt::Write;
-
-    let mut writer = Writer {
-        column_position: 0,
-        color_code: ColorCode::new(Color::LightGreen, Color::Black),
-        buffer: unsafe { Unique::new(0xb8000 as *mut _) },
-    };
-
-    writeln!(writer, "Hello!");
-    writeln!(writer, "The numbers are {} and {}", 42, 1.0/3.0);
-}