Fix clear() function

rust_experiments/src/lib.rs

@@ -6,23 +6,23 @@ extern crate rlibc;
 
 #[no_mangle]
 pub extern fn rust_main() {
-    let gamarjoba = b"Gamarjoba, munde";
-    let color_byte = 0x1f; // white on blue
-
-    let mut gamarjoba_colored = [color_byte; 32];
-    for (i, char_byte) in gamarjoba.into_iter().enumerate() {
-        gamarjoba_colored[i*2] = *char_byte;
-    }
-
-    //write to center of VGA buffer
-    let buffer_ptr = (0xb8000 + 1988) as *mut _;
-    unsafe { *buffer_ptr = gamarjoba_colored };
-
-    vga_buffer::write_to_coord(10,10, b'f');
+    clear();
 
     loop {}
 }
 
+fn clear() {
+
+    let blank_color = vga_buffer::ColorCode::new(
+        vga_buffer::Color::White,
+        vga_buffer::Color::Black);
+    for i in 0..vga_buffer::BUFFER_WIDTH {
+        for j in 0..vga_buffer::BUFFER_HEIGHT {
+            vga_buffer::write_to_coord(i, j, b' ', blank_color);
+        }
+    }
+}
+
 mod vga_buffer {
     #[repr(u8)]
     pub enum Color {
@@ -45,9 +45,9 @@ mod vga_buffer {
     }
 
     #[derive(Clone, Copy)]
-    struct ColorCode(u8);
+    pub struct ColorCode(u8);
     impl ColorCode {
-        const fn new(foreground: Color, background: Color) -> ColorCode {
+        pub const fn new(foreground: Color, background: Color) -> ColorCode {
             ColorCode((background as u8) << 4 | (foreground as u8))
         }
     }
@@ -58,16 +58,21 @@ mod vga_buffer {
         color_code: ColorCode
     }
 
-    const BUFFER_HEIGHT: usize = 25;
-    const BUFFER_WIDTH: usize = 80;
+    pub const BUFFER_HEIGHT: usize = 25;
+    pub const BUFFER_WIDTH: usize = 80;
     const BUFFER_PTR: usize = 0xb8000;
 
-    pub fn write_to_coord(x: usize, y: usize, character: u8) {
-        let ptr = BUFFER_PTR + (2*x as usize) + (BUFFER_HEIGHT * 2 * y as usize);
+    pub fn write_to_coord(x: usize, y: usize, character: u8, color_code: ColorCode) {
+        let ptr = BUFFER_PTR + (2*x as usize) + (BUFFER_WIDTH*2*y as usize);
         let data = ScreenChar {
             ascii_char: character,
-            color_code: ColorCode::new(Color::White, Color::Red)
+            color_code: color_code,
         };
+
+        if x > BUFFER_WIDTH || y > BUFFER_HEIGHT {
+            return;
+        }
+
         unsafe {
             *(ptr as *mut _) = data;
         }