base print function

src/main.rs

@@ -13,14 +13,7 @@ static HELLO: &[u8] = b"Hello World!";
 
 #[no_mangle]
 pub extern "C" fn _start() -> ! {
-    let vga_buffer = 0xb8000 as *mut u8;
-
-    for (i, &byte) in HELLO.iter().enumerate() {
-        unsafe {
-            *vga_buffer.offset(i as isize * 2) = byte;
-            *vga_buffer.offset(i as isize * 2 + 1) = 0xb;
-        }
-    }
+    vga_buffer::print_something();  
 
     loop {}
 }

src/vga_buffer.rs

@@ -24,10 +24,10 @@ pub enum Color {
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
 #[repr(transparent)]
-struct ColorCode(u8)
+struct ColorCode(u8);
 
 impl ColorCode {
-    fn new(foreground: Color, background = Color) -> ColorCode {
+    fn new(foreground: Color, background: Color) -> ColorCode {
         ColorCode((background as u8) << 4 | (foreground as u8))
     }
 }
@@ -42,7 +42,7 @@ struct ScreenChar {
 const BUFFER_HEIGHT: usize = 25;
 const BUFFER_WIDTH: usize = 80;
 
-#repr(transparent)
+#[repr(transparent)]
 struct Buffer {
     chars: [[ScreenChar; BUFFER_WIDTH]; BUFFER_HEIGHT],
 }
@@ -54,7 +54,7 @@ pub struct Writer {
 }
 
 impl Writer {
-    pub fn write_byte(&mut self, byteL u8) {
+    pub fn write_byte(&mut self, byte: u8) {
         match byte {
             b'\n' => self.new_line(),
             byte => {
@@ -63,7 +63,7 @@ impl Writer {
                 }
 
                 let row = BUFFER_HEIGHT - 1;
-                let col self.column_position;
+                let col = self.column_position;
 
                 let color_code = self.color_code;
                 self.buffer.chars[row][col] = ScreenChar {
@@ -74,6 +74,28 @@ impl Writer {
             }
         }
     }
+    pub fn write_string(&mut self, s: &str) {
+        for byte in s.bytes() {
+            match byte {
+                // printable ASCII byte or newline
+                0x20..=0x7e | b'\n' => self.write_byte(byte),
+                // not part of printable ascii range
+                _ => self.write_byte(0xfe),
+            }
+        }
+    }
 
     fn new_line(&mut self) {/*TODO */}
+}
+
+pub fn print_something() {
+    let mut writer = Writer {
+        column_position: 0,
+        color_code: ColorCode::new(Color::Yellow, Color::Black),
+        buffer: unsafe { &mut *(0xb8000 as *mut Buffer) },
+    };
+
+    writer.write_byte(b'H');
+    writer.write_string("ello ");
+    writer.write_string("World!")
 }