Make writer instance global

Cargo.lock

@@ -7,6 +7,8 @@ name = "KarxOS"
 version = "0.1.0"
 dependencies = [
  "bootloader",
+ "lazy_static",
+ "spin",
  "volatile",
 ]
 
@@ -16,6 +18,21 @@ version = "0.9.19"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "b7c452074efc3c0bfb241fb7bc87df04741c7c85e926f6a07c05f8fbd6008240"
 
+[[package]]
+name = "lazy_static"
+version = "1.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e2abad23fbc42b3700f2f279844dc832adb2b2eb069b2df918f455c4e18cc646"
+dependencies = [
+ "spin",
+]
+
+[[package]]
+name = "spin"
+version = "0.5.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6e63cff320ae2c57904679ba7cb63280a3dc4613885beafb148ee7bf9aa9042d"
+
 [[package]]
 name = "volatile"
 version = "0.2.7"

Cargo.toml

@@ -8,3 +8,8 @@ edition = "2018"
 [dependencies]
 bootloader = "0.9.8"
 volatile = "0.2.6"
+spin = "0.5.2"
+
+[dependencies.lazy_static]
+version = "1.0"
+features = ["spin_no_std"]

src/main.rs

@@ -12,7 +12,9 @@ fn panic(_info: &PanicInfo) -> ! {
 
 #[no_mangle]
 pub extern "C" fn _start() -> ! {
-    vga_buffer::print_something();
+    use core::fmt::Write;
+    vga_buffer::WRITER.lock().write_str("Hello there\n").unwrap();
+    writeln!(vga_buffer::WRITER.lock(), "General Kenobi").unwrap();
 
     loop {}
 }

src/vga_buffer.rs

@@ -1,5 +1,7 @@
 use volatile::Volatile;
 use core::fmt;
+use lazy_static::lazy_static;
+use spin::Mutex;
 
 #[allow(dead_code)]
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
@@ -118,16 +120,11 @@ impl fmt::Write for Writer {
     }
 }
 
-pub fn print_something() {
-    use core::fmt::Write;
-    let mut writer = Writer {
+lazy_static! {
+    pub static ref WRITER: Mutex<Writer> = Mutex::new(Writer {
         column_position: 0,
         color_code: ColorCode::new(Color::White, Color::Black),
         buffer: unsafe { &mut *(0xb8000 as *mut Buffer) }
-    };
-
-    writeln!(writer, "Hello world!").unwrap();
-    writeln!(writer, "Hello again!").unwrap();
-
+    });
 }