Update skip-data-init example

Author: KushalMeghani1644

cortex-m-rt/examples/skip-data-init.rs

@@ -20,16 +20,23 @@
 #![no_main]
 #![no_std]
 
-use panic_halt as _;
-
+use core::sync::atomic::{AtomicU32, Ordering};
 use cortex_m_rt::entry;
+use cortex_m_semihosting::hprintln;
+use panic_halt as _;
 
-static mut COUNTER: u32 = 42;
+static COUNTER: AtomicU32 = AtomicU32::new(42);
 
 #[entry]
 fn main() -> ! {
-    unsafe {
-        COUNTER += 1;
+    let prev = COUNTER.fetch_add(1, Ordering::Relaxed);
+    let new = COUNTER.load(Ordering::Relaxed);
+
+    hprintln!("Previous counter value: {}", prev);
+    hprintln!("New counter value: {}", new);
+
+    if prev != 42 || new != 43 {
+        panic!("Unexpected COUNTER value! Data section may not be initialized.");
     }
 
     loop {