turn into a Cargo crate

examples/override-exception-handler.rs

@@ -0,0 +1,46 @@
+//! Overriding an exception
+//!
+//! **NOTE** You have to disable the `cortex-m-rt` crate's "exceptions" feature
+//! to make this work.
+
+#![feature(used)]
+#![no_std]
+
+extern crate cortex_m;
+extern crate cortex_m_rt;
+
+use core::ptr;
+
+use cortex_m::{asm, exception};
+
+fn main() {
+    unsafe {
+        // Invalid memory access
+        ptr::read_volatile(0x2FFF_FFFF as *const u32);
+    }
+}
+
+extern "C" fn hard_fault(_: exception::HardFault) {
+    // You'll hit this breakpoint rather than the one in cortex-m-rt
+    asm::bkpt()
+}
+
+// When the "exceptions" feature is disabled, you'll have to provide this symbol
+#[allow(dead_code)]
+#[used]
+#[link_section = ".rodata.exceptions"]
+static EXCEPTIONS: exception::Handlers = exception::Handlers {
+    // This is the exception handler override
+    hard_fault: hard_fault,
+    ..exception::DEFAULT_HANDLERS
+};
+
+// As we are not using interrupts, we just register a dummy catch all handler
+#[allow(dead_code)]
+#[used]
+#[link_section = ".rodata.interrupts"]
+static INTERRUPTS: [extern "C" fn(); 240] = [default_handler; 240];
+
+extern "C" fn default_handler() {
+    asm::bkpt();
+}