From be760456359ec7cd4e701df47d3ec3b93feba602 Mon Sep 17 00:00:00 2001
From: Paul van Tilburg <paul@luon.net>
Date: Thu, 7 Mar 2019 22:40:41 +0100
Subject: [PATCH] Introduce the LedCycle struct to bundle a lot of led cycle
 functionality

---
 src/main.rs | 89 ++++++++++++++++++++++++++++++++++++++++-------------
 1 file changed, 68 insertions(+), 21 deletions(-)

diff --git a/src/main.rs b/src/main.rs
index b575a5d..5f929e1 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -14,8 +14,6 @@ use rtfm::app;
 type Led = hal::gpio::gpiod::PD<Output<PushPull>>;
 type UserButton = hal::gpio::gpioa::PA0<Input<Floating>>;
 
-const PERIOD: u32 = 8_000_000;
-
 pub enum LedDirection {
     Clockwise,
     CounterClockwise,
@@ -30,12 +28,66 @@ impl LedDirection {
     }
 }
 
+pub struct LedCycle {
+    pub enabled: bool,
+    pub direction: LedDirection,
+    pub index: usize,
+    pub leds: [Led; 4]
+}
+
+impl LedCycle {
+    const PERIOD: u32 = 8_000_000;
+
+    fn from(leds: [Led; 4]) -> LedCycle {
+        LedCycle {
+            enabled: true,
+            direction: LedDirection::Clockwise,
+            index: 0,
+            leds
+        }
+    }
+
+    fn disable(&mut self) {
+        self.enabled = false;
+    }
+
+    fn enable(&mut self) {
+        self.enabled = true;
+    }
+
+    fn reverse(&mut self) {
+        self.direction = self.direction.flip();
+    }
+
+    fn advance(&mut self) {
+        let num_leds = self.leds.len();
+
+        self.leds[self.index].set_high();
+        self.leds[(self.index + 2) % num_leds].set_low();
+
+        self.index = match self.direction {
+            LedDirection::Clockwise => (self.index + 1) % num_leds,
+            LedDirection::CounterClockwise => (self.index + 3) % num_leds,
+        };
+    }
+
+    fn all_on(&mut self) {
+        for led in self.leds.iter_mut() {
+            led.set_high();
+        }
+    }
+
+    fn all_off(&mut self) {
+        for led in self.leds.iter_mut() {
+            led.set_low();
+        }
+    }
+}
+
 #[app(device = hal::stm32)]
 const APP: () = {
     static mut button: UserButton = ();
-    static mut leds: [Led; 4] = ();
-    static mut led_cycle_direction: LedDirection = LedDirection::Clockwise;
-    static mut led_index: usize = 0;
+    static mut led_cycle: LedCycle = ();
     static mut exti: EXTI = ();
 
     #[init(spawn = [switch_leds])]
@@ -48,6 +100,7 @@ const APP: () = {
             gpiod.pd14.into_push_pull_output().downgrade(),
             gpiod.pd15.into_push_pull_output().downgrade(),
         ];
+        let led_cycle = LedCycle::from(leds);
         spawn.switch_leds().unwrap();
 
         // Set up the EXTI0 interrup for the user button.
@@ -57,28 +110,22 @@ const APP: () = {
         button.enable_interrupt(&mut exti);
         button.trigger_on_edge(&mut exti, Edge::RISING);
 
-        init::LateResources { button, exti, leds }
+        init::LateResources { button, exti, led_cycle }
     }
 
-    #[task(schedule = [switch_leds],
-        resources = [led_index, led_cycle_direction, leds])]
+    #[task(schedule = [switch_leds], resources = [led_cycle])]
     fn switch_leds() {
-        let led_index = *resources.led_index;
-        let num_leds = resources.leds.len();
-
-        resources.leds[led_index].set_high();
-        resources.leds[(led_index + 2) % num_leds].set_low();
-        *resources.led_index = match *resources.led_cycle_direction {
-            LedDirection::Clockwise => (led_index + 1) % num_leds,
-            LedDirection::CounterClockwise => (led_index + 3) % num_leds,
-        };
-
-        schedule.switch_leds(scheduled + PERIOD.cycles()).unwrap();
+        resources.led_cycle.lock(|led_cycle| {
+            if led_cycle.enabled {
+                led_cycle.advance();
+                schedule.switch_leds(scheduled + LedCycle::PERIOD.cycles()).unwrap();
+            }
+        });
     }
 
-    #[interrupt(binds = EXTI0, resources = [button, exti, led_cycle_direction])]
+    #[interrupt(binds = EXTI0, resources = [button, exti, led_cycle])]
     fn button_pressed() {
-        *resources.led_cycle_direction = resources.led_cycle_direction.flip();
+        resources.led_cycle.lock(|led_cycle| led_cycle.reverse());
 
         resources.button.clear_interrupt_pending_bit(resources.exti);
     }