//! Blinks an LED

#![deny(unsafe_code)]
#![no_std]
#![no_main]
//MCU: STM32F103C8T699
extern crate panic_halt;

use rtfm::{app, Instant, Duration};
use stm32f103xx_hal::{
    gpio::gpioc::PC13,
    gpio::gpioa::PA0,
    gpio::Output,
    gpio::PushPull,
    prelude::*,
    time::Hertz,
};

const STEP_MIN_S: f32 = 1.1e-6;
const DIR_MIN_S: f32 = 201e-9;

fn hertz_to_cycles(sysclock: Hertz, hertz: Hertz) -> u32 {
    sysclock.0 / hertz.0
}

fn seconds_to_cycles(sysclock: Hertz, seconds: f32) -> u32 {
    (sysclock.0 as f32 * seconds) as u32
}

#[app(device = stm32f103xx)]
const APP: () = {
    static mut LED_GLOBAL: PC13<Output<PushPull>> = ();
    static mut STEP_PIN: PA0<Output<PushPull>> = ();
    static mut PERIOD: u32 = ();
    static STEP_MIN_DURATION: Duration = ();
    static DIR_MIN_DURATION: Duration = ();


    #[init(schedule = [toggle])]
    unsafe fn init() {
        let mut rcc = device.RCC.constrain();
        let mut gpioa = device.GPIOA.split(&mut rcc.apb2);
        let mut gpioc = device.GPIOC.split(&mut rcc.apb2);
        let mut flash = device.FLASH.constrain();
        let clocks = rcc.cfgr.freeze(&mut flash.acr);
        let sysclock = clocks.sysclk();
        let period = hertz_to_cycles(sysclock, 50.hz());
        schedule.toggle(Instant::now() + period.cycles()).unwrap();
        PERIOD = period;
        LED_GLOBAL = gpioc.pc13.into_push_pull_output(&mut gpioc.crh);
        STEP_PIN = gpioa.pa0.into_push_pull_output(&mut gpioa.crl);
        STEP_MIN_DURATION = seconds_to_cycles(sysclock, STEP_MIN_S).cycles();
        DIR_MIN_DURATION = seconds_to_cycles(sysclock, DIR_MIN_S).cycles();
    }

    #[task(schedule = [toggle, set_step_high, set_step_low], resources = [LED_GLOBAL, PERIOD, STEP_MIN_DURATION])]
    fn toggle() {
        resources.LED_GLOBAL.toggle();
        *resources.PERIOD = (*resources.PERIOD as f32 * 1.1) as u32;
        schedule.toggle(scheduled + resources.PERIOD.cycles()).unwrap();
        schedule.set_step_high(scheduled + resources.PERIOD.cycles()).unwrap();
        schedule.set_step_low(scheduled + resources.PERIOD.cycles() + *resources.STEP_MIN_DURATION).unwrap();
    }

    fn schedule_step() { // <--- error: this item must live outside the `#[app]` module
    }

    #[task(resources = [STEP_PIN])]
    fn set_step_high() {
        resources.STEP_PIN.set_high();
    }

    #[task(resources = [STEP_PIN])]
    fn set_step_low() {
        resources.STEP_PIN.set_low();
    }

    extern "C" {
        fn USART1();
    }
};