//! Using a device crate
//!
//! Crates generated using [`svd2rust`] are referred to as device crates. These
//! crates provides an API to access the peripherals of a device. When you
//! depend on one of these crates and the "rt" feature is enabled you don't need
//! link to the cortex-m-rt crate.
//!
//! [`svd2rust`]: https://crates.io/crates/svd2rust
//!
//! Device crates also provide an `interrupt!` macro to register interrupt
//! handlers.
//!
//! This example depends on the [`stm32f103xx`] crate so you'll have to add it
//! to your Cargo.toml.
//!
//! [`stm32f103xx`]: https://crates.io/crates/stm32f103xx
//!
//! ```
//! $ edit Cargo.toml && cat $_
//! [dependencies.stm32f103xx]
//! features = ["rt"]
//! version = "0.8.0"
//! ```
//!
//! ---

#![deny(warnings)]
#![feature(const_fn)]
#![no_std]

extern crate cortex_m;
extern crate cortex_m_semihosting;
#[macro_use(exception, interrupt)]
extern crate stm32f103xx;

use core::cell::RefCell;
use core::fmt::Write;

use cortex_m::interrupt::{self, Mutex};
use cortex_m::peripheral::syst::SystClkSource;
use cortex_m_semihosting::hio::{self, HStdout};
use stm32f103xx::Interrupt;

static HSTDOUT: Mutex<RefCell<Option<HStdout>>> =
    Mutex::new(RefCell::new(None));

static NVIC: Mutex<RefCell<Option<cortex_m::peripheral::NVIC>>> =
    Mutex::new(RefCell::new(None));

fn main() {
    let global_p = cortex_m::Peripherals::take().unwrap();
    interrupt::free(|cs| {
        let hstdout = HSTDOUT.borrow(cs);
        if let Ok(fd) = hio::hstdout() {
            *hstdout.borrow_mut() = Some(fd);
        }

        let mut nvic = global_p.NVIC;
        nvic.enable(Interrupt::TIM2);
        *NVIC.borrow(cs).borrow_mut() = Some(nvic);

        let mut syst = global_p.SYST;
        syst.set_clock_source(SystClkSource::Core);
        syst.set_reload(8_000_000); // 1s
        syst.enable_counter();
        syst.enable_interrupt();
    });
}

exception!(SYS_TICK, tick);

fn tick() {
    interrupt::free(|cs| {
        let hstdout = HSTDOUT.borrow(cs);
        if let Some(hstdout) = hstdout.borrow_mut().as_mut() {
            writeln!(*hstdout, "Tick").ok();
        }

        if let Some(nvic) = NVIC.borrow(cs).borrow_mut().as_mut() {
            nvic.set_pending(Interrupt::TIM2);
        }
    });
}

interrupt!(TIM2, tock, locals: {
    tocks: u32 = 0;
});

fn tock(l: &mut TIM2::Locals) {
    l.tocks += 1;

    interrupt::free(|cs| {
        let hstdout = HSTDOUT.borrow(cs);
        if let Some(hstdout) = hstdout.borrow_mut().as_mut() {
            writeln!(*hstdout, "Tock ({})", l.tocks).ok();
        }
    });
}