Add `print!` and `println!` macros and a `clear_screen` function

src/lib.rs

@@ -8,16 +8,15 @@ extern crate rlibc;
 extern crate volatile;
 extern crate spin;
 
+#[macro_use]
 mod vga_buffer;
 
 #[no_mangle]
 pub extern fn rust_main() {
     // ATTENTION: we have a very small stack and no guard page
 
-    use core::fmt::Write;
-
-    vga_buffer::WRITER.lock().write_str("Hello again");
-    write!(vga_buffer::WRITER.lock(), ", some numbers: {} {}", 42, 1.337);
+    vga_buffer::clear_screen();
+    println!("Hello World{}", "!");
 
     loop{}
 }

src/vga_buffer.rs

@@ -123,3 +123,22 @@ impl fmt::Write for Writer {
         Ok(())
     }
 }
+
+macro_rules! print {
+    ($($arg:tt)*) => ({
+        use core::fmt::Write;
+        let mut writer = $crate::vga_buffer::WRITER.lock();
+        writer.write_fmt(format_args!($($arg)*)).unwrap();
+    });
+}
+
+macro_rules! println {
+    ($fmt:expr) => (print!(concat!($fmt, "\n")));
+    ($fmt:expr, $($arg:tt)*) => (print!(concat!($fmt, "\n"), $($arg)*));
+}
+
+pub fn clear_screen() {
+    for _ in 0..BUFFER_HEIGHT {
+        println!("");
+    }
+}