Module f3::examples::led_compass_2

A LED compass that points to the North, take 2

#![no_main]
#![no_std]

#[macro_use]
extern crate f3;

use f3::I16x3;
use f3::led::Direction;
use f3::{delay, led, lsm303dlhc};

#[export_name = "main"]
pub extern "C" fn main() -> ! {
    loop {
        let I16x3 { x, y, .. } = lsm303dlhc::magnetic_field();

        led::all_off();

        // NOTE
        // - tan(PI / 8) ~= 2 / 5
        // - tan(3 * PI / 8) ~= 12 / 5
        let _2_x = 2 * x;
        let _2_y = 2 * y;
        let _5_x = 5 * x;
        let _5_y = 5 * y;
        let _12_x = 12 * x;
        let _12_y = 12 * y;

        let dir = match (x > 0, y > 0) {
            (false, false) => {
                if _5_y > _2_x {
                    Direction::North
                } else if _5_y > _12_x {
                    Direction::NorthWest
                } else {
                    Direction::West
                }
            }
            (false, true) => {
                if _5_y < -_2_x {
                    Direction::North
                } else if _5_y < -_12_x {
                    Direction::NorthEast
                } else {
                    Direction::East
                }
            }
            (true, false) => {
                if -_5_y < _2_x {
                    Direction::South
                } else if _5_y < _12_x {
                    Direction::SouthWest
                } else {
                    Direction::West
                }
            }
            (true, true) => {
                if _5_y < _2_x {
                    Direction::South
                } else if _5_y < _12_x {
                    Direction::SouthEast
                } else {
                    Direction::East
                }
            }
        };

        dir.on();

        delay::ms(100);
    }
}