hardware::Atreus: Implement a custom readCols()

Manually unrolling the loop results in code that's 0.3ms faster, at the cost of
a bit of PROGMEM.

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

src/kaleidoscope/hardware/technomancy/Atreus.cpp

@@ -71,6 +71,23 @@ void Atreus::resetDevice() {
   asm volatile("jmp 0x7E00");
 }
 
+uint16_t Atreus::readCols() {
+  uint16_t results = 0;
+  results |= (!READ_PIN(KeyboardHardware.matrix_col_pins[0]) << 0);
+  results |= (!READ_PIN(KeyboardHardware.matrix_col_pins[1]) << 1);
+  results |= (!READ_PIN(KeyboardHardware.matrix_col_pins[2]) << 2);
+  results |= (!READ_PIN(KeyboardHardware.matrix_col_pins[3]) << 3);
+  results |= (!READ_PIN(KeyboardHardware.matrix_col_pins[4]) << 4);
+  results |= (!READ_PIN(KeyboardHardware.matrix_col_pins[5]) << 5);
+  results |= (!READ_PIN(KeyboardHardware.matrix_col_pins[6]) << 6);
+  results |= (!READ_PIN(KeyboardHardware.matrix_col_pins[7]) << 7);
+  results |= (!READ_PIN(KeyboardHardware.matrix_col_pins[8]) << 8);
+  results |= (!READ_PIN(KeyboardHardware.matrix_col_pins[9]) << 9);
+  results |= (!READ_PIN(KeyboardHardware.matrix_col_pins[10]) << 10);
+
+  return results;
+}
+
 }
 }
 }

src/kaleidoscope/hardware/technomancy/Atreus.h

@@ -38,6 +38,7 @@ namespace kaleidoscope {
 namespace hardware {
 namespace technomancy {
 class Atreus: public kaleidoscope::hardware::ATMegaKeyboard {
+  friend class ATMegaKeyboard;
  public:
   Atreus(void) {}
 
@@ -49,6 +50,9 @@ class Atreus: public kaleidoscope::hardware::ATMegaKeyboard {
   static constexpr int8_t led_count = 0;
 
   void resetDevice();
+
+ protected:
+  uint16_t readCols();
 };
 
 #define KEYMAP(                                                               \