Add Stopwatch application

It can be started, stopped, and cleared. It also continues to run if
you leave the screen.

firmware/Application/Screens/StopwatchScreen.cpp

@@ -0,0 +1,173 @@
+/*
+ * Copyright (C) 2019  Max Regan
+ *
+ * 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.
+ */
+
+#include <cstring>
+
+#include "Application/Screens/StopwatchScreen.h"
+#include "Application/SystemFonts.h"
+#include "Bsp/SystemTime.h"
+
+using BSP::ReturnCode;
+using BSP::Time;
+using BSP::Schedule::NextTime;
+
+StopwatchScreen::StopwatchScreen(BSP::DisplayDriver &display,
+                             ScreenManager &manager)
+    : m_display(display)
+    , m_manager(manager)
+    , m_is_running(false)
+    , m_accumulated_time()
+    , m_last_time()
+    , m_font(default_font)
+
+{}
+
+ReturnCode StopwatchScreen::init()
+{
+    return ReturnCode::OK;
+}
+
+NextTime StopwatchScreen::execute()
+{
+    refresh();
+
+    if (m_is_running) {
+        add_time();
+    }
+
+    return NextTime::asap();
+}
+
+static char get_char_for_digit(uint8_t bcd_digit)
+{
+    return (bcd_digit % 10) + '0';
+}
+
+void StopwatchScreen::display_number(uint32_t *x, uint32_t y,
+                                     uint32_t tens, uint32_t ones)
+{
+    char time_str[3] = { 0 };
+    time_str[0] = get_char_for_digit(tens);
+    time_str[1] = get_char_for_digit(ones);
+    time_str[2] = '\0';
+
+    m_display.string_at(x, y, time_str, &m_font);
+}
+
+void StopwatchScreen::display_number(uint32_t *x, uint32_t y,
+                                     uint32_t hundreds, uint32_t tens, uint32_t ones)
+{
+    char time_str[4] = { 0 };
+    time_str[0] = get_char_for_digit(hundreds);
+    time_str[1] = get_char_for_digit(tens);
+    time_str[2] = get_char_for_digit(ones);
+    time_str[3] = '\0';
+
+    m_display.string_at(x, y, time_str, &m_font);
+}
+
+void StopwatchScreen::refresh()
+{
+    m_display.clear();
+
+    //uint32_t width = m_display.get_width();
+    uint32_t x = (m_display.get_width() - m_font.width * 7) / 2;
+    uint32_t y = (m_display.get_height() - m_font.height * 2) / 2;
+
+    uint64_t total_millis = BSP::Time::to_millis(m_accumulated_time);
+    uint32_t millis = total_millis % 1000;
+
+    uint64_t total_seconds = total_millis / 1000;
+    uint32_t seconds = total_seconds % 60;
+
+    uint64_t total_minutes = total_seconds / 60;
+    uint32_t minutes = total_minutes % 60;
+
+    uint64_t hours = total_minutes / 60;
+
+    display_number(&x, y,
+                   hours / 100, hours / 10, hours);
+
+    m_display.string_at(&x, y, ":", &m_font);
+
+    display_number(&x, y,
+                   minutes / 10, minutes % 10);
+
+    m_display.string_at(&x, y, ":", &m_font);
+
+    y += m_font.height;
+    x = (m_display.get_width() - 6 * m_font.width) / 2 ;
+
+    display_number(&x, y,
+                   seconds / 10, seconds);
+
+    m_display.string_at(&x, y, ".", &m_font);
+
+    display_number(&x, y,
+                   millis / 100, millis / 10, millis);
+
+    m_display.refresh();
+}
+
+void StopwatchScreen::add_time()
+{
+    BSP::time_t time;
+
+    BSP::SystemTimer::get_time(time);
+
+    m_accumulated_time += time - m_last_time;
+
+    m_last_time = time;
+}
+
+void StopwatchScreen::notify_up_button()
+{
+    m_manager.pop_screen();
+    return;
+}
+
+void StopwatchScreen::notify_middle_button()
+{
+    BSP::SystemTimer::get_time(m_last_time);
+    m_accumulated_time = 0;
+}
+
+void StopwatchScreen::notify_down_button()
+{
+    if (!m_is_running) {
+        // Start
+        BSP::SystemTimer::get_time(m_last_time);
+    } else {
+        // Stop
+        add_time();
+    }
+
+    m_is_running = !m_is_running;
+    return;
+}
+
+void StopwatchScreen::enable()
+{
+}
+
+void StopwatchScreen::disable()
+{
+}