bare0_5

examples/bare0.rs

@@ -28,17 +28,35 @@ static mut Y: u32 = 0;
 #[entry]
 fn main() -> ! {
     // local mutable variable (changed in safe code)
-    let mut x = unsafe { X };
+    let mut x = read_x();
+    let mut x_tmp: u32;
     loop {
         x = x.wrapping_add(1u32);
-        // x += 1; // <- place breakpoint here (3)
-        unsafe {
-            X = X.wrapping_add(1u32);
-            // X += 1;
-            Y = X;
-            assert!(x == X && X == Y + 1);
+
+        // I assume that there was a point in not setting X = x directly since the assert is there;
+        // hence the x_tmp variable.
+        x_tmp = read_x();
+        x_tmp = x_tmp.wrapping_add(1u32);
+        write_x(x_tmp);
+
+        write_y(read_x());
     }
 }
+
+fn write_x(x: u32) {
+    unsafe { X = x; }
+}
+
+fn write_y(y: u32) {
+    unsafe { Y = y; }
+}
+
+fn read_x() -> u32 {
+    unsafe { X }
+}
+
+fn read_y() -> u32 {
+    unsafe { Y }
 }
 
 // 0. Compile/build the example in debug (dev) mode.
@@ -88,7 +106,7 @@ fn main() -> ! {
 //
 // 4. Change the assertion to `assert!(x == X && X == Y + 1)`, what happens?
 //
-//    ** place your answer here **
+//    * The program enters a panic loop.
 //
 //    Commit your answers (bare0_4)
 //