cortex-m-quickstart 0.1.2

//! Debugging a crash (exception)
//!
//! The `cortex-m-rt` crate provides functionality for this through a default
//! exception handler. When an exception is hit, the default handler will
//! trigger a breakpoint and in this debugging context the stacked registers
//! are accessible.
//!
//! In you run the example below, you'll be able to inspect the state of your
//! program under the debugger using these commands:
//!
//! ```
//! (gdb) # Stacked registers = program state during the crash
//! (gdb) print/x *_sr
//! $1 = cortex_m::exception::StackedRegisters {
//!   r0 = 0x2fffffff,
//!   r1 = 0x2fffffff,
//!   r2 = 0x0,
//!   r3 = 0x0,
//!   r12 = 0x0,
//!   lr = 0x8000443,
//!   pc = 0x8000190,
//!   xpsr = 0x61000200,
//! }
//!
//! (gdb) # What exception was triggered?
//! (gdb) print _e
//! $2 = cortex_m::exception::Exception::HardFault
//!
//! (gdb) # Where did we come from?
//! (gdb) print _e
//! ```

#![feature(used)]
#![no_std]

extern crate cortex_m;
extern crate cortex_m_rt;

use core::ptr;

use cortex_m::asm;

fn main() {
    // Read an invalid memory address
    unsafe {
        ptr::read_volatile(0x2FFF_FFFF as *const u32);
    }
}

// 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();
}