Test text interface

test/src/main.rs

@@ -14,20 +14,27 @@ fn panic_handler(_info: &PanicInfo) -> ! {
 
 const OUTPUT: *mut u32 = 0x2000_0000 as *mut u32;
 const BTNS: *mut u8 = 0x2000_0008 as *mut u8;
+const TEXT: *mut u32 = 0x2000_000C as *mut u32;
 const SCREEN: *mut u32 = 0x2000_0080 as *mut u32;
 
+const HELLO_WORLD: &[u8; 13] = b" Hello world!";
+
 #[entry]
 fn main() -> ! {
-    loop {
+    unsafe {
+        SCREEN.write_volatile(0b101);
+    }
+    for i in 0..31 {
         unsafe {
-            SCREEN.write_volatile(0b101);
+            let mut x = SCREEN.offset(i).read_volatile();
+            x <<= 1;
+            SCREEN.offset(i + 1).write_volatile(x);
         }
-        for i in 0..31 {
-            unsafe {
-                let mut x = SCREEN.offset(i).read_volatile();
-                x <<= 1;
-                SCREEN.offset(i+1).write_volatile(x);
-            }
+    }
+    for ch in HELLO_WORLD {
+        unsafe {
+            TEXT.write_volatile(*ch as u32);
         }
     }
+    loop {}
 }