hardware/Atreus: From select/unselectRow, go to toggleRow

Instead of having a separate function for selecting and unselecting rows, have
only one that toggles them - we only ever want to toggle them anyway. While
there, optimize it slightly, by not toggling `DDRD`: if we set those in `setup`,
they'll remain set, and there's no need to toggle them.

This makes the code cleaner and smaller, at the cost of four bytes of RAM.

Signed-off-by: Gergely Nagy <algernon@keyboard.io>

src/kaleidoscope/hardware/Atreus.cpp

@@ -46,12 +46,15 @@ uint16_t Atreus::masks_[ROWS];
 uint8_t Atreus::debounce_matrix_[ROWS][COLS];
 uint8_t Atreus::debounce = 3;
 
+constexpr uint8_t Atreus::row_pins[4];
+
 void Atreus::setup(void) {
   wdt_disable();
   delay(100);
 
   for (uint8_t i = 0; i < ROWS; i++) {
-    unselectRow(i);
+    DDRD |= _BV(row_pins[i]);
+    PORTD |= _BV(row_pins[i]);
     keyState_[i] = previousKeyState_[i] = 0;
   }
 
@@ -82,50 +85,8 @@ void Atreus::setup(void) {
   TIMSK1 = _BV(TOIE1);
 }
 
-void Atreus::selectRow(uint8_t row) {
+void Atreus::toggleRow(uint8_t row) {
-  switch (row) {
+  PORTD ^= _BV(row_pins[row]);
-  case 0:
-    DDRD  |= (_BV(0));
-    PORTD &= ~(_BV(0));
-    break;
-  case 1:
-    DDRD  |= (_BV(1));
-    PORTD &= ~(_BV(1));
-    break;
-  case 2:
-    DDRD  |= (_BV(3));
-    PORTD &= ~(_BV(3));
-    break;
-  case 3:
-    DDRD  |= (_BV(2));
-    PORTD &= ~(_BV(2));
-    break;
-  default:
-    break;
-  }
-}
-
-void Atreus::unselectRow(uint8_t row) {
-  switch (row) {
-  case 0:
-    DDRD  &= ~(_BV(0));
-    PORTD |= (_BV(0));
-    break;
-  case 1:
-    DDRD  &= ~(_BV(1));
-    PORTD |= (_BV(1));
-    break;
-  case 2:
-    DDRD  &= ~(_BV(3));
-    PORTD |= (_BV(3));
-    break;
-  case 3:
-    DDRD  &= ~(_BV(2));
-    PORTD |= (_BV(2));
-    break;
-  default:
-    break;
-  }
 }
 
 uint16_t Atreus::readCols() {
@@ -149,9 +110,9 @@ void Atreus::readMatrixRow(uint8_t current_row) {
 
   mask = debounceMaskForRow(current_row);
 
-  selectRow(current_row);
+  toggleRow(current_row);
   cols = (readCols() & mask) | (keyState_[current_row] & ~mask);
-  unselectRow(current_row);
+  toggleRow(current_row);
   debounceRow(cols ^ keyState_[current_row], current_row);
   keyState_[current_row] = cols;
 }

src/kaleidoscope/hardware/Atreus.h

@@ -127,14 +127,15 @@ class Atreus {
   static uint8_t debounce;
 
  private:
+  static constexpr uint8_t row_pins[4] = {0, 1, 3, 2};
+
   static uint16_t previousKeyState_[matrix_rows];
   static uint16_t keyState_[matrix_rows];
   static uint16_t masks_[matrix_rows];
 
   static void readMatrixRow(uint8_t row);
   static uint16_t readCols();
-  static void selectRow(uint8_t row);
+  static void toggleRow(uint8_t row);
-  static void unselectRow(uint8_t row);
 
   static uint8_t debounce_matrix_[matrix_rows][matrix_columns];
   static uint16_t debounceMaskForRow(uint8_t row);