#![no_std]
#![no_main]

// pick a panicking behavior
extern crate panic_halt; // you can put a breakpoint on `rust_begin_unwind` to catch panics
// extern crate panic_abort; // requires nightly
// extern crate panic_itm; // logs messages over ITM; requires ITM support
// extern crate panic_semihosting; // logs messages to the host stderr; requires a debugger

use cortex_m::{self, peripheral::syst::SystClkSource};
use cortex_m_rt::entry;
use msp432p401r;

use core::num::Wrapping;

const PIN0: u8 = (1u8 << 0);
const PIN1: u8 = (1u8 << 1);
const PIN2: u8 = (1u8 << 2);
//const PIN3: u8 = (1u8 << 3);
const PIN4: u8 = (1u8 << 4);
//const PIN5: u8 = (1u8 << 5);
//const PIN6: u8 = (1u8 << 6);
//const PIN7: u8 = (1u8 << 7);

const WDOG_PWORD: u8 = 0x5a;

#[entry]
fn main() -> ! {
    let cp = cortex_m::Peripherals::take().unwrap();
    let p = msp432p401r::Peripherals::take().unwrap();

    let mut syst = cp.SYST;
    let wdt = p.WDT_A;
    let dio = p.DIO;

    // disable watchdog timer
    wdt.wdtctl.write(|w| unsafe {
        w.wdtpw().bits(WDOG_PWORD)
         .wdthold().wdthold_1()
    });

    // configure the system timer to wrap around every ~1 second
    syst.set_clock_source(SystClkSource::Core);
    syst.set_reload(20_000);
    syst.enable_counter();

    // configure digital IO pins
    dio.padir.modify(|_r, w| unsafe {
        w.p1dir().bits(PIN0)
         .p2dir().bits(PIN0 | PIN1 | PIN2)
    });

    // Enable pull-up on P1.4 switch
    dio.paren.modify(|_r, w| unsafe { w.p1ren().bits(PIN4) });
    dio.pads.modify(|_r, w| unsafe { w.p1ds().bits(PIN4) });

    // Turn on LED1 on P1.0 and enable pull-up on P1.1 switch
    dio.paout.write(|w| unsafe {
        w.p1out().bits(PIN0 | PIN4)
         .p2out().bits(0)
    });

    let mut count: Wrapping<u16> = Wrapping(0);
    let mut input: u8;
    loop {
        while !syst.has_wrapped() {}

        // The button pulls the input to GND
        input = (dio.pain.read().p1in().bits() & PIN4) >> 4;

        count += Wrapping(1);
        let _led1: u8 = ((count.0 & 0x0100) >> 8) as u8;
        let led2: u8 = ((count.0 & 0b0000_0111_0000_0000) >> 8) as u8;

        // toggle LEDs
        dio.paout.write(|w| unsafe {
            w.p1out().bits(input | PIN4)
             .p2out().bits(led2)
        });
    }
}