make the hello example work

examples/hello.rs

@@ -2,29 +2,33 @@
 //!
 //! ---
 
-#![feature(used)]
+#![feature(asm)]
+#![no_main]
 #![no_std]
 
-extern crate cortex_m;
+#[macro_use]
 extern crate cortex_m_rt;
-extern crate cortex_m_semihosting;
+extern crate cortex_m_semihosting as sh;
 extern crate panic_abort; // panicking behavior
 
 use core::fmt::Write;
 
-use cortex_m::asm;
-use cortex_m_semihosting::hio;
+use sh::hio;
 
-fn main() {
+main!(main);
+
+fn main() -> ! {
     let mut stdout = hio::hstdout().unwrap();
     writeln!(stdout, "Hello, world!").unwrap();
+
+    loop {}
 }
 
-// As we are not using interrupts, we just register a dummy catch all handler
-#[link_section = ".vector_table.interrupts"]
-#[used]
-static INTERRUPTS: [extern "C" fn(); 240] = [default_handler; 240];
+exception!(DefaultHandler, dh);
 
-extern "C" fn default_handler() {
-    asm::bkpt();
+fn dh(_nr: u8) -> ! {
+    loop {}
 }
+
+// As we are not using interrupts, we just bind them all to the `DefaultHandler` exception handler
+interrupts!(DefaultHandler);