v0.2.0

examples/panic.rs

@@ -1,33 +1,56 @@
-//! Redirecting `panic!` messages
+//! Defining the panic handler
 //!
-//! The `cortex-m-rt` crate provides two options to redirect `panic!` messages
-//! through these two Cargo features:
+//! The panic handler can be defined through the `panic_fmt` [language item][1].
+//! Make sure that the "abort-on-panic" feature of the cortex-m-rt crate is
+//! disabled to avoid redefining the language item.
 //!
-//! - `panic-over-semihosting`. `panic!` messages will be printed to the OpenOCD
-//!    console using semihosting. This is slow.
+//! [1]: https://doc.rust-lang.org/unstable-book/language-features/lang-items.html
 //!
-//! - `panic-over-itm`. `panic!` messages will be send through the ITM port 0.
-//!   This is much faster but requires ITM support on the device.
-//!
-//! If neither of these options is specified then the `panic!` message will be
-//! lost. Note that all `panic!`s will trigger a debugger breakpoint.
+//! ---
 
+#![feature(core_intrinsics)]
+#![feature(lang_items)]
 #![feature(used)]
 #![no_std]
 
 extern crate cortex_m;
 extern crate cortex_m_rt;
+extern crate cortex_m_semihosting;
+
+use core::fmt::Write;
+use core::intrinsics;
 
 use cortex_m::asm;
+use cortex_m_semihosting::hio;
 
 fn main() {
     panic!("Oops");
 }
 
+#[lang = "panic_fmt"]
+#[no_mangle]
+unsafe extern "C" fn rust_begin_unwind(
+    args: core::fmt::Arguments,
+    file: &'static str,
+    line: u32,
+    col: u32,
+) -> ! {
+    if let Ok(mut stdout) = hio::hstdout() {
+        write!(stdout, "panicked at '")
+            .and_then(|_| {
+                stdout
+                    .write_fmt(args)
+                    .and_then(|_| writeln!(stdout, "', {}:{}", file, line))
+            })
+            .ok();
+    }
+
+    intrinsics::abort()
+}
+
 // As we are not using interrupts, we just register a dummy catch all handler
-#[allow(dead_code)]
+#[link_section = ".vector_table.interrupts"]
 #[used]
-#[link_section = ".rodata.interrupts"]
 static INTERRUPTS: [extern "C" fn(); 240] = [default_handler; 240];
 
 extern "C" fn default_handler() {