//! Sends "Hello, world!" through the ITM port 0
//!
//! ITM is much faster than semihosting. Like 4 orders of magnitude or so.
//!
//! **NOTE** Cortex-M0 chips don't support ITM.
//!
//! You'll have to connect the microcontroller's SWO pin to the SWD interface. Note that some
//! development boards don't provide this option.
//!
//! You'll need [`itmdump`] to receive the message on the host plus you'll need to uncomment two
//! `monitor` commands in the `.gdbinit` file.
//!
//! [`itmdump`]: https://docs.rs/itm/0.2.1/itm/
//!
//! ---

#![no_main]
#![no_std]

#[macro_use]
extern crate cortex_m;
#[macro_use]
extern crate cortex_m_rt as rt;
extern crate panic_semihosting;

use cortex_m::{asm, Peripherals};
use rt::ExceptionFrame;

entry!(main);

fn main() -> ! {
    let mut p = Peripherals::take().unwrap();
    let stim = &mut p.ITM.stim[0];

    iprintln!(stim, "Hello, world!");

    loop {
        asm::bkpt();
    }
}

// define the hard fault handler
exception!(HardFault, hard_fault);

fn hard_fault(ef: &ExceptionFrame) -> ! {
    panic!("HardFault at {:#?}", ef);
}

// define the default exception handler
exception!(*, default_handler);

fn default_handler(irqn: i16) {
    panic!("Unhandled exception (IRQn = {})", irqn);
}