From 0edc261e6ba9fb4468ec9a8b1c68c5a1bc46fc72 Mon Sep 17 00:00:00 2001
From: Tilman Sauerbeck <tilman@code-monkey.de>
Date: Sun, 22 Mar 2020 15:26:39 +0100
Subject: [PATCH] application: Add the button module.

Provides debouncing for GPIOs.
---
 SConscript.target         |  1 +
 src/application/button.rs | 86 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 87 insertions(+)
 create mode 100644 src/application/button.rs

diff --git a/SConscript.target b/SConscript.target
index afd10bd..539db88 100644
--- a/SConscript.target
+++ b/SConscript.target
@@ -84,6 +84,7 @@ for s in ['intermediate', 'final']:
 
 application_source_files = [
     'src/application/main.rs', # Must be listed first (see below).
+    'src/application/button.rs',
     'src/application/uart0.rs',
 ]
 
diff --git a/src/application/button.rs b/src/application/button.rs
new file mode 100644
index 0000000..1fff70b
--- /dev/null
+++ b/src/application/button.rs
@@ -0,0 +1,86 @@
+/*
+ * Copyright (c) 2020 Tilman Sauerbeck (tilman at code-monkey de)
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+ * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+ * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+use common::gpio;
+use common::systick;
+
+enum State {
+    WaitPress,
+    WaitRelease,
+    WaitTimeout,
+}
+
+pub struct Button {
+    gpio: u32,
+    pin: u32,
+    state: State,
+    start_press_ticks: u32,
+}
+
+impl Button {
+    pub fn new(gpio: u32, pin: u32) -> Button {
+        Button {
+            gpio: gpio,
+            pin: pin,
+            state: State::WaitPress,
+            start_press_ticks: 0,
+        }
+    }
+
+    pub fn has_been_held_for_ms(&mut self, delay_ms: u32) -> bool {
+        let mut has_been_held = false;
+
+        self.state = match self.state {
+            State::WaitPress => {
+                if (gpio::get(self.gpio) & self.pin) != 0 {
+                    State::WaitPress
+                } else {
+                    self.start_press_ticks = systick::now();
+
+                    State::WaitTimeout
+                }
+            },
+            State::WaitRelease => {
+                if (gpio::get(self.gpio) & self.pin) == 0 {
+                    State::WaitRelease
+                } else {
+                    State::WaitPress
+                }
+            },
+            State::WaitTimeout => {
+                if (gpio::get(self.gpio) & self.pin) != 0 {
+                    State::WaitPress
+                } else if systick::has_timeout_ms(self.start_press_ticks,
+                                                  delay_ms) {
+                    has_been_held = true;
+
+                    State::WaitRelease
+                } else {
+                    State::WaitTimeout
+                }
+            },
+        };
+
+        has_been_held
+    }
+}
-- 
2.30.2