bare0

examples/bare0.rs

@@ -9,7 +9,7 @@
 // Minimal runtime / startup for Cortex-M microcontrollers
 extern crate cortex_m_rt;
 
-const X_INIT: u32 = 10;
+const X_INIT: u32 = 0;
 
 static mut X: u32 = X_INIT;
 static mut Y: u32 = 0;
@@ -27,6 +27,64 @@ fn main() {
         }
     }
 }
+// 1. run the program in the debugger,
+//    let the program run for a while and then press pause
+//    look in the (Local) Variables view what do you find
+//    ** your answer here **
+//
+//    in the Expressions (WHATCH) view add X and Y
+//    what do you find
+//
+//    ** your answer here **
+//    step through one complete iteration of the loop
+//    and see how the (Local) Varibles are updated
+//    can you foresee what will eventually happen?
+// 	  ** place your answer here **
+//    
+//    commit your answers (bare0_1)
+//
+// 2. alter the constant X_INIT so that line 22 directly causes the x to wrap
+// 	  what happens when x wraps
+//    ** your answer here **
+//
+//    commit your answers (bare0_2)
+//
+// 3. change += opertions to wrapping_add
+//    place a breakpoint at line 22
+//    load and run the progam, what happens
+//    ** your answer here **
+//
+//    now continue exectution, what happens
+//    ** your answer here **
+//
+//    commit your answers (bare0_3)
+//    
+//    (if the program did not succed back to the breakpoint 
+//    you have some fault in the program and go back to 3)
+//    
+// 4. change the asserion to assert!(x == X && X == Y + 1), what happens
+//    ** place your answer here **
+//
+//    commit your answers (bare0_4)
+//
+// 5. remove the assertion and
+//    
+//    make "safe" functions for reading and writing X and Y
+//    e.g. read_x, read_y, write_x, write_y
+//
+//    rewrite the program to use ONLY "safe" code besides the
+//    read/write functions (which are internally "unsafe")
+//
+//    commit your solution (bare0_5)
+//
+// 6*. optional
+//    implement a read_u32/write_u32, taking a reference to a 
+//    "static" variable
+//    
+//    rewrite the program to use this abstraction instead of "read_x", etc.
+// 
+//    commit your solution (bare0_6)
+// 
 
 // As we are not using interrupts, we just register a dummy catch all handler
 #[link_section = ".vector_table.interrupts"]