Add cursor-moving functionality

rust_experiments/src/lib.rs

@@ -135,31 +135,42 @@ mod x86_asm {
 }
 
 fn timer_callback(count: u64) {
-    use vga_buffer::{Color, checkerboard};
-    if count % 1000  == 0 {
-        checkerboard(Color::White);
-    }
-    if count % 1000 == 500 {
-        checkerboard(Color::LightCyan);
+    use vga_buffer::{Color, print_u32, checkerboard, clear, move_cursor};
+
+    if count < 10 {
+        clear();
     }
 
-    vga_buffer::print_u32(count as u32, 0);
+    if count < 3000 {
+
+        move_cursor((count % 80) as u8, 2);
+
+        print_u32(count as u32, 20);
+
+    } else {
+        if count % 1000  == 0 {
+            checkerboard(Color::White);
+        }
+        if count % 1000 == 500 {
+            checkerboard(Color::LightCyan);
+        }
+        move_cursor((count % 80) as u8, 2);
+    }
+
+    print_u32(count as u32, 0);
 }
 
 #[no_mangle]
 pub extern fn rust_main() {
     use vga_buffer::{clear, checkerboard, Color};
-    clear();
-    checkerboard(Color::Red);
+    //clear();
+    //checkerboard(Color::Red);
 
     loop {
 
     }
 }
 
-
-
-
 // 123  |3,2,1
 mod util {
     pub fn u32_to_chars(n: u32) -> [u8; 10] {
@@ -307,6 +318,23 @@ mod vga_buffer {
             *(ptr as *mut _) = data;
         }
     }
+
+    pub fn move_cursor(x: u8, y: u8) {
+        use x86_asm::{outb};
+        const CURSOR_COMMAND_PORT: u16 = 0x3d4;
+        const CURSOR_DATA_PORT: u16 = 0x3d5;
+
+        let position: u16 = (y as u16)*80 + (x as u16);
+        let low_bits = (position & 0xff) as u8;
+        let high_bits = (position >> 8) as u8;
+
+        unsafe {
+            outb(CURSOR_COMMAND_PORT, 14);
+            outb(CURSOR_DATA_PORT, low_bits);
+            outb(CURSOR_COMMAND_PORT, 15);
+            outb(CURSOR_DATA_PORT, high_bits);
+        }
+    }
 }
 
 #[cfg(not(test))]