Merge pull request #15 from phil-opp/printing_to_screen_improvements

Add the clear_screen function from the blog post

src/lib.rs

@@ -25,6 +25,7 @@ mod vga_buffer;
 #[no_mangle]
 pub extern fn rust_main() {
     // ATTENTION: we have a very small stack and no guard page
+    vga_buffer::clear_screen();
     println!("Hello World{}", "!");
 
     loop{}

src/vga_buffer.rs

@@ -23,6 +23,12 @@ macro_rules! print {
     });
 }
 
+pub fn clear_screen() {
+    for _ in 0..BUFFER_HEIGHT {
+        println!("");
+    }
+}
+
 #[allow(dead_code)]
 #[repr(u8)]
 pub enum Color {
@@ -85,7 +91,7 @@ impl Writer {
 
     fn clear_row(&mut self, row: usize) {
         let blank = ScreenChar {
-            ascii_character: ' ' as u8,
+            ascii_character: b' ',
             color_code: self.color_code,
         };
         self.buffer().chars[row] = [blank; BUFFER_WIDTH];