move out most of text

see https://github.com/rust-embedded/book/pull/20

examples/exception.rs

@@ -1,8 +1,8 @@
 //! Overriding an exception handler
 //!
-//! You can override an exception handler using the [`exception!`][1] macro.
+//! You can override an exception handler using the [`#[exception]`][1] attribute.
 //!
-//! [1]: https://docs.rs/cortex-m-rt/0.5.0/cortex_m_rt/macro.exception.html
+//! [1]: https://rust-embedded.github.io/cortex-m-rt/0.6.1/cortex_m_rt_macros/fn.exception.html
 //!
 //! ---
 
@@ -10,21 +10,16 @@
 #![no_main]
 #![no_std]
 
-extern crate cortex_m;
-#[macro_use]
-extern crate cortex_m_rt as rt;
-extern crate cortex_m_semihosting as sh;
-extern crate panic_semihosting;
+extern crate panic_halt;
 
 use core::fmt::Write;
 
 use cortex_m::peripheral::syst::SystClkSource;
 use cortex_m::Peripherals;
-use rt::ExceptionFrame;
-use sh::hio::{self, HStdout};
-
-entry!(main);
+use cortex_m_rt::{entry, exception};
+use cortex_m_semihosting::hio::{self, HStdout};
 
+#[entry]
 fn main() -> ! {
     let p = Peripherals::take().unwrap();
     let mut syst = p.SYST;
@@ -38,27 +33,15 @@ fn main() -> ! {
     loop {}
 }
 
-// try commenting out this line: you'll end in `default_handler` instead of in `sys_tick`
-exception!(SysTick, sys_tick, state: Option<HStdout> = None);
+#[exception]
+fn SysTick() {
+    static mut STDOUT: Option<HStdout> = None;
 
-fn sys_tick(state: &mut Option<HStdout>) {
-    if state.is_none() {
-        *state = Some(hio::hstdout().unwrap());
+    if STDOUT.is_none() {
+        *STDOUT = Some(hio::hstdout().unwrap());
     }
 
-    if let Some(hstdout) = state.as_mut() {
+    if let Some(hstdout) = STDOUT.as_mut() {
         hstdout.write_str(".").unwrap();
     }
 }
-
-exception!(HardFault, hard_fault);
-
-fn hard_fault(ef: &ExceptionFrame) -> ! {
-    panic!("HardFault at {:#?}", ef);
-}
-
-exception!(*, default_handler);
-
-fn default_handler(irqn: i16) {
-    panic!("Unhandled exception (IRQn = {})", irqn);
-}