Some more text drawing logic

rust_experiments/src/lib.rs

@@ -37,7 +37,8 @@ pub extern fn rust_handle_timer() {
         global_timer_count += 1;
     }
 
-    timer_callback(gtc);
+    //timer_callback(gtc);
+    timer_callback2(gtc);
 }
 
 #[no_mangle]
@@ -135,6 +136,19 @@ mod x86_asm {
     }
 }
 
+fn timer_callback2(count: u64) {
+    use vga_buffer::*;
+
+    let color = Color::LightCyan;
+
+    if count % 500 == 0 {
+        checkerboard(color);
+    } else if count % 500 == 250 {
+        alt_checkerboard(color);
+    }
+
+}
+
 fn timer_callback(count: u64) {
     use vga_buffer::{Color, print_u32, checkerboard, clear, move_cursor};
 
@@ -164,7 +178,7 @@ fn timer_callback(count: u64) {
 #[no_mangle]
 pub extern fn rust_main() {
     use vga_buffer::{clear, checkerboard, Color};
-    //clear();
+    clear();
     //checkerboard(Color::Red);
 
     loop {
@@ -254,15 +268,21 @@ mod vga_buffer {
     }
 
     pub fn checkerboard(color: Color) {
+        checkerboard_logic(color, false);
+    }
+    pub fn alt_checkerboard(color: Color) {
+        checkerboard_logic(color, true);
+    }
 
+    fn checkerboard_logic(color: Color, alternate: bool) {
         let active = ColorCode::new(color, color);
         let blank = ColorCode::new(Color::White, Color::Black);
         for i in 0..BUFFER_WIDTH {
             for j in 0..BUFFER_HEIGHT {
                 if (i + j) % 2 == 0 {
-                    write_to_coord(i, j, b' ', active);
+                    write_to_coord(i, j, b' ', if alternate { active } else { blank } );
                 } else {
-                    write_to_coord(i, j, b' ', blank);
+                    write_to_coord(i, j, b' ', if alternate { blank } else { active });
                 }
             }
         }