Track which deck is active on each side of the MC7000

This is needed to handle the deck switching correctly (since we only
want to transfer shift state if the deck was actually switched, not if
the same deck's button has been pressed, since the latter would yield us
the same shift inversion bug again).

res/controllers/Denon-MC7000-scripts.js

@@ -112,6 +112,9 @@ MC7000.factor = [];
 //Set Shift button state to false as default
 MC7000.shift = [false, false, false, false];
 
+// For each side whether the top or bottom deck is active.
+MC7000.topDeckActive = [true, true];
+
 // initialize the PAD Mode to Hot Cue and all others off when starting
 MC7000.PADModeCue = [true, true, true, true];
 MC7000.PADModeCueLoop = [false, false, false, false];
@@ -181,6 +184,10 @@ MC7000.init = function() {
     engine.makeConnection("[Channel3]", "VuMeter", MC7000.VuMeter);
     engine.makeConnection("[Channel4]", "VuMeter", MC7000.VuMeter);
 
+    // Switch to active decks
+    midi.sendShortMsg(MC7000.topDeckActive[0] ? 0x90 : 0x92, 0x08, 0x7F);
+    midi.sendShortMsg(MC7000.topDeckActive[1] ? 0x91 : 0x93, 0x08, 0x7F);
+
     // Platter Ring LED mode
     midi.sendShortMsg(0x90, 0x64, MC7000.modeSingleLED);
     midi.sendShortMsg(0x91, 0x64, MC7000.modeSingleLED);
@@ -889,31 +896,34 @@ MC7000.crossFaderCurve = function(control, value) {
 
 // Update state on deck changes
 MC7000.switchDeck = function(channel, control, value, status, group) {
+    var deckOffset = script.deckFromGroup(group) - 1;
+    var isTopDeck = deckOffset < 2;
+    var side = deckOffset % 2;
+
+    var previousDeckOffset;
+    switch (deckOffset) {
+    case 0:
+        previousDeckOffset = 2;
+        break;
+    case 1:
+        previousDeckOffset = 3;
+        break;
+    case 2:
+        previousDeckOffset = 0;
+        break;
+    case 3:
+        previousDeckOffset = 1;
+        break;
+    }
+
     // We need to 'transfer' the shift state when switching decks,
     // otherwise it will get stuck and result in an 'inverted'
     // shift after switching back to the deck.
     // Since the controller switches immediately upon pressing down,
     // we only do this when value is high.
 
-    if (value === 0x7F) {
-        var deckOffset = script.deckFromGroup(group) - 1;
-
-        var previousDeckOffset;
-        switch (deckOffset) {
-        case 0:
-            previousDeckOffset = 2;
-            break;
-        case 1:
-            previousDeckOffset = 3;
-            break;
-        case 2:
-            previousDeckOffset = 0;
-            break;
-        case 3:
-            previousDeckOffset = 1;
-            break;
-        }
-
+    if (value === 0x7F && MC7000.topDeckActive[side] !== isTopDeck) {
+        MC7000.topDeckActive[side] = isTopDeck;
         MC7000.shift[deckOffset] = MC7000.shift[previousDeckOffset];
         MC7000.shift[previousDeckOffset] = false;
     }