Handle button state

1 files changed, 57 insertions, 0 deletions

diff --git a/src/button.c b/src/button.c
new file mode 100644
index 0000000..34d799c
--- /dev/null
+++ b/src/button.c
@@ -0,0 +1,57 @@
+#include <avr/io.h>
+#include <stdint.h>
+
+#include "avr/interrupt.h"
+#include "button.h"
+#include "rtc.h"
+
+bool is_button_active = false;
+
+uint16_t button_tick_count = 0;
+
+ISR(PCINT0_vect, ISR_FLATTEN) { button_tick(); }
+
+void button_tick() {
+  switch (check_button_state()) {
+  case BUTTON_PRESSED:
+    if (seconds <= 10)
+      seconds = 0;
+    else
+      seconds -= 10;
+    break;
+  case BUTTON_LONG_PRESSED:
+    seconds += 10;
+    break;
+  default:
+    break;
+  }
+}
+
+enum ButtonState check_button_state() {
+  if (is_button_active && button_tick_count >= LONG_PRESS_TICK_COUNT) {
+    button_tick_count = 0;
+    is_button_active = false;
+    return BUTTON_LONG_PRESSED;
+  }
+
+  bool in_debounce_period = is_button_active && button_tick_count > 0 &&
+                            button_tick_count < DEBOUNCE_TICK_COUNT;
+
+  // Ignore readings from debounce period
+  if (!in_debounce_period) {
+    DDRA &= ~(1 << PA0);
+    PORTA &= ~(1 << PA0);
+    is_button_active = (PINA & (1 << PA0)) == 0;
+  }
+
+  if (is_button_active) {
+    button_tick_count++;
+  } else {
+    if (button_tick_count >= DEBOUNCE_TICK_COUNT) {
+      button_tick_count = 0;
+      return BUTTON_PRESSED;
+    }
+  }
+
+  return BUTTON_IDLE;
+}