From 67aa99ca30b10cdcac8114639bde872912e985f7 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Tomek=20Re=CC=A8kawek?= <rekawek@adobe.com>
Date: Sat, 26 Nov 2016 08:06:36 +0100
Subject: [PATCH] Handle caps lock.

---
 mac_plus_ps2/mac_plus_ps2.ino | 22 +++++++++++++++++++---
 1 file changed, 19 insertions(+), 3 deletions(-)

diff --git a/mac_plus_ps2/mac_plus_ps2.ino b/mac_plus_ps2/mac_plus_ps2.ino
index d13fa12..8c7b6d1 100644
--- a/mac_plus_ps2/mac_plus_ps2.ino
+++ b/mac_plus_ps2/mac_plus_ps2.ino
@@ -12,6 +12,7 @@
 #define MAC_CLOCK_PIN 6
 
 #define NULL_TRANSITION 0x7b
+#define CAPS_LOCK       0x73
 
 PS2Keyboard keyboard;
 unsigned int scanCodesTable[256];
@@ -24,7 +25,6 @@ void setup() {
   initScancodes();
 
   keyboard.begin(PS2_DATA_PIN, PS2_CLOCK_PIN);
-  //debug();
 
   pinMode(LED_BUILTIN, OUTPUT);
   pinMode(MAC_CLOCK_PIN, OUTPUT);
@@ -72,7 +72,7 @@ byte readCmd() {
   delayMicroseconds(20);
   
   while (digitalRead(MAC_DATA_PIN) != LOW);
-  delayMicroseconds(400);
+  delayMicroseconds(400); // this is apparently required so we don't lose the first digit
   byte cmd = readByte();
   while (digitalRead(MAC_DATA_PIN) != HIGH);
   
@@ -162,17 +162,33 @@ unsigned int getExtendedTransition() {
   }
 }
 
+boolean capsLockPressed = false;
+
 unsigned int translate(byte scanCode, boolean extended, boolean released) {
   unsigned int translated = extended ? extScanCodesTable[scanCode] : scanCodesTable[scanCode];
   if (translated == NULL_TRANSITION) {
     return NULL_TRANSITION;
   } else if (released) {
-    return translated | 0x80;
+    if (translated == CAPS_LOCK) {
+      return handleCapsLockRelease();
+    } else {
+      return translated | 0x80;
+    }
   } else {
     return translated;
   }
 }
 
+unsigned int handleCapsLockRelease() {
+  if (capsLockPressed) {
+    capsLockPressed = false;
+    return CAPS_LOCK | 0x80;
+  } else {
+    capsLockPressed = true;
+    return NULL_TRANSITION;
+  }
+}
+
 byte waitForScanCode() {
   while (true) {
     byte s = keyboard.getScanCode();