From 32b5aceefc5524bd7d2a751fa3587023b5e5030e Mon Sep 17 00:00:00 2001
From: Per <Per Lindgren>
Date: Mon, 15 Jan 2018 21:02:49 +0100
Subject: [PATCH] bare0
---
examples/bare0.rs | 60 ++++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 59 insertions(+), 1 deletion(-)
diff --git a/examples/bare0.rs b/examples/bare0.rs
index fdb45a2..00581f2 100644
--- a/examples/bare0.rs
+++ b/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"]
--
GitLab