Local link cable and infrared emulation in the Cocoa port

Cocoa/AppDelegate.h

@@ -1,6 +1,6 @@
 #import <Cocoa/Cocoa.h>
 
-@interface AppDelegate : NSObject <NSApplicationDelegate, NSUserNotificationCenterDelegate>
+@interface AppDelegate : NSObject <NSApplicationDelegate, NSUserNotificationCenterDelegate, NSMenuDelegate>
 
 @property IBOutlet NSWindow *preferencesWindow;
 @property (strong) IBOutlet NSView *graphicsTab;
@@ -10,6 +10,7 @@
 - (IBAction)showPreferences: (id) sender;
 - (IBAction)toggleDeveloperMode:(id)sender;
 - (IBAction)switchPreferencesTab:(id)sender;
+@property (weak) IBOutlet NSMenuItem *linkCableMenuItem;
 
 @end
 

Cocoa/AppDelegate.m

@@ -82,9 +82,28 @@
         [(NSMenuItem *)anItem setState:[[NSUserDefaults standardUserDefaults] boolForKey:@"DeveloperMode"]];
     }
     
+    if (anItem == self.linkCableMenuItem) {
+        return [[NSDocumentController sharedDocumentController] documents].count > 1;
+    }
     return true;
 }
 
+- (void)menuNeedsUpdate:(NSMenu *)menu
+{
+    NSMutableArray *items = [NSMutableArray array];
+    NSDocument *currentDocument = [[NSDocumentController sharedDocumentController] currentDocument];
+    
+    for (NSDocument *document in [[NSDocumentController sharedDocumentController] documents]) {
+        if (document == currentDocument) continue;
+        NSMenuItem *item = [[NSMenuItem alloc] initWithTitle:document.displayName action:@selector(connectLinkCable:) keyEquivalent:@""];
+        item.representedObject = document;
+        item.image = [[NSWorkspace sharedWorkspace] iconForFile:document.fileURL.path];
+        [item.image setSize:NSMakeSize(16, 16)];
+        [items addObject:item];
+    }
+    menu.itemArray = items;
+}
+
 - (IBAction) showPreferences: (id) sender
 {
     NSArray *objects;
@@ -109,4 +128,8 @@
 {
     [[NSDocumentController sharedDocumentController] openDocumentWithContentsOfFile:notification.identifier display:YES];
 }
+
+- (IBAction)nop:(id)sender
+{
+}
 @end

Cocoa/Document.h

@@ -6,6 +6,7 @@
 @class GBCheatWindowController;
 
 @interface Document : NSDocument <NSWindowDelegate, GBImageViewDelegate, NSTableViewDataSource, NSTableViewDelegate, NSSplitViewDelegate>
+@property (readonly) GB_gameboy_t *gb;
 @property (strong) IBOutlet GBView *view;
 @property (strong) IBOutlet NSTextView *consoleOutput;
 @property (strong) IBOutlet NSPanel *consoleWindow;
@@ -36,10 +37,12 @@
 @property (strong) IBOutlet NSBox *debuggerVerticalLine;
 @property (strong) IBOutlet NSPanel *cheatsWindow;
 @property (strong) IBOutlet GBCheatWindowController *cheatWindowController;
+@property (readonly) Document *partner;
+@property (readonly) bool isSlave;
 
 -(uint8_t) readMemory:(uint16_t) addr;
 -(void) writeMemory:(uint16_t) addr value:(uint8_t)value;
 -(void) performAtomicBlock: (void (^)())block;
-
+-(void) connectLinkCable:(NSMenuItem *)sender;
 @end
 

Cocoa/Document.m

@@ -28,6 +28,7 @@ enum model {
     NSMutableAttributedString *pending_console_output;
     NSRecursiveLock *console_output_lock;
     NSTimer *console_output_timer;
+    NSTimer *hex_timer;
     
     bool fullScreen;
     bool in_sync_input;
@@ -47,7 +48,7 @@ enum model {
     bool oamUpdating;
     
     NSMutableData *currentPrinterImageData;
-    enum {GBAccessoryNone, GBAccessoryPrinter, GBAccessoryWorkboy} accessory;
+    enum {GBAccessoryNone, GBAccessoryPrinter, GBAccessoryWorkboy, GBAccessoryLinkCable} accessory;
     
     bool rom_warning_issued;
     
@@ -66,6 +67,12 @@ enum model {
     size_t audioBufferNeeded;
     
     bool borderModeChanged;
+    
+    /* Link cable*/
+    Document *master;
+    Document *slave;
+    signed linkOffset;
+    bool linkCableBit;
 }
 
 @property GBAudioClient *audioClient;
@@ -81,6 +88,10 @@ enum model {
 - (void) gotNewSample:(GB_sample_t *)sample;
 - (void) rumbleChanged:(double)amp;
 - (void) loadBootROM:(GB_boot_rom_t)type;
+- (void)linkCableBitStart:(bool)bit;
+- (bool)linkCableBitEnd;
+- (void)infraredStateChanged:(bool)state;
+
 @end
 
 static void boot_rom_load(GB_gameboy_t *gb, GB_boot_rom_t type)
@@ -160,6 +171,26 @@ static void rumbleCallback(GB_gameboy_t *gb, double amp)
     [self rumbleChanged:amp];
 }
 
+
+static void linkCableBitStart(GB_gameboy_t *gb, bool bit_to_send)
+{
+    Document *self = (__bridge Document *)GB_get_user_data(gb);
+    [self linkCableBitStart:bit_to_send];
+}
+
+static bool linkCableBitEnd(GB_gameboy_t *gb)
+{
+    Document *self = (__bridge Document *)GB_get_user_data(gb);
+    return [self linkCableBitEnd];
+}
+
+static void infraredStateChanged(GB_gameboy_t *gb, bool on, uint64_t cycles_since_last_update)
+{
+    Document *self = (__bridge Document *)GB_get_user_data(gb);
+    [self infraredStateChanged:on];
+}
+
+
 @implementation Document
 {
     GB_gameboy_t gb;
@@ -264,6 +295,7 @@ static void rumbleCallback(GB_gameboy_t *gb, double amp)
     GB_set_rewind_length(&gb, [[NSUserDefaults standardUserDefaults] integerForKey:@"GBRewindLength"]);
     GB_apu_set_sample_callback(&gb, audioCallback);
     GB_set_rumble_callback(&gb, rumbleCallback);
+    GB_set_infrared_callback(&gb, infraredStateChanged);
     [self updateRumbleMode];
 }
 
@@ -335,9 +367,8 @@ static void rumbleCallback(GB_gameboy_t *gb, double amp)
     [_view setRumble:amp];
 }
 
-- (void) run
+- (void) preRun
 {
-    running = true;
     GB_set_pixels_output(&gb, self.view.pixels);
     GB_set_sample_rate(&gb, 96000);
     self.audioClient = [[GBAudioClient alloc] initWithRendererBlock:^(UInt32 sampleRate, UInt32 nFrames, GB_sample_t *buffer) {
@@ -368,7 +399,7 @@ static void rumbleCallback(GB_gameboy_t *gb, double amp)
     if (![[NSUserDefaults standardUserDefaults] boolForKey:@"Mute"]) {
         [self.audioClient start];
     }
-    NSTimer *hex_timer = [NSTimer timerWithTimeInterval:0.25 target:self selector:@selector(reloadMemoryView) userInfo:nil repeats:YES];
+    hex_timer = [NSTimer timerWithTimeInterval:0.25 target:self selector:@selector(reloadMemoryView) userInfo:nil repeats:YES];
     [[NSRunLoop mainRunLoop] addTimer:hex_timer forMode:NSDefaultRunLoopMode];
     
     /* Clear pending alarms, don't play alarms while playing */
@@ -388,19 +419,58 @@ static void rumbleCallback(GB_gameboy_t *gb, double amp)
             }
         }
     }
+}
 
-    while (running) {
+static unsigned *multiplication_table_for_frequency(unsigned frequency)
-        if (rewind) {
+{
-            rewind = false;
+    unsigned *ret = malloc(sizeof(*ret) * 0x100);
-            GB_rewind_pop(&gb);
+    for (unsigned i = 0; i < 0x100; i++) {
-            if (!GB_rewind_pop(&gb)) {
+        ret[i] = i * frequency;
-                rewind = self.view.isRewinding;
+    }
+    return ret;
+}
+
+- (void) run
+{
+    assert(!master);
+    running = true;
+    [self preRun];
+    if (slave) {
+        [slave preRun];
+        unsigned *masterTable = multiplication_table_for_frequency(GB_get_clock_rate(&gb));
+        unsigned *slaveTable = multiplication_table_for_frequency(GB_get_clock_rate(&slave->gb));
+        while (running) {
+            if (linkOffset <= 0) {
+                linkOffset += slaveTable[GB_run(&gb)];
+            }
+            else {
+                linkOffset -= masterTable[GB_run(&slave->gb)];
             }
         }
-        else {
+        free(masterTable);
-            GB_run(&gb);
+        free(slaveTable);
+        [slave postRun];
+    }
+    else {
+        while (running) {
+            if (rewind) {
+                rewind = false;
+                GB_rewind_pop(&gb);
+                if (!GB_rewind_pop(&gb)) {
+                    rewind = self.view.isRewinding;
+                }
+            }
+            else {
+                GB_run(&gb);
+            }
         }
     }
+    [self postRun];
+    stopping = false;
+}
+
+- (void)postRun
+{
     [hex_timer invalidate];
     [audioLock lock];
     memset(audioBuffer, 0, (audioBufferSize - audioBufferPosition) * sizeof(*audioBuffer));
@@ -431,18 +501,31 @@ static void rumbleCallback(GB_gameboy_t *gb, double amp)
         [[NSUserDefaults standardUserDefaults] setBool:true forKey:@"GBNotificationsUsed"];
     }
     [_view setRumble:0];
-    stopping = false;
 }
 
 - (void) start
 {
-    if (running) return;
     self.view.mouseHidingEnabled = (self.mainWindow.styleMask & NSFullScreenWindowMask) != 0;
+    if (master) {
+        [master start];
+        return;
+    }
+    if (running) return;
     [[[NSThread alloc] initWithTarget:self selector:@selector(run) object:nil] start];
 }
 
 - (void) stop
 {
+    if (master) {
+        if (!master->running) return;
+        GB_debugger_set_disabled(&gb, true);
+        if (GB_debugger_is_stopped(&gb)) {
+            [self interruptDebugInputRead];
+        }
+        [master stop];
+        GB_debugger_set_disabled(&gb, false);
+        return;
+    }
     if (!running) return;
     GB_debugger_set_disabled(&gb, true);
     if (GB_debugger_is_stopped(&gb)) {
@@ -519,6 +602,10 @@ static void rumbleCallback(GB_gameboy_t *gb, double amp)
 
 - (IBAction)togglePause:(id)sender
 {
+    if (master) {
+        [master togglePause:sender];
+        return;
+    }
     if (running) {
         [self stop];
     }
@@ -749,6 +836,7 @@ static void rumbleCallback(GB_gameboy_t *gb, double amp)
 
 - (void)close
 {
+    [self disconnectLinkCable];
     [[NSUserDefaults standardUserDefaults] setInteger:self.mainWindow.frame.size.width forKey:@"LastWindowWidth"];
     [[NSUserDefaults standardUserDefaults] setInteger:self.mainWindow.frame.size.height forKey:@"LastWindowHeight"];
     [self stop];
@@ -760,9 +848,7 @@ static void rumbleCallback(GB_gameboy_t *gb, double amp)
 {
     [self log:"^C\n"];
     GB_debugger_break(&gb);
-    if (!running) {
+    [self start];
-        [self start];
-    }
     [self.consoleWindow makeKeyAndOrderFront:nil];
     [self.consoleInput becomeFirstResponder];
 }
@@ -781,10 +867,13 @@ static void rumbleCallback(GB_gameboy_t *gb, double amp)
 - (BOOL)validateUserInterfaceItem:(id<NSValidatedUserInterfaceItem>)anItem
 {
     if ([anItem action] == @selector(mute:)) {
-        [(NSMenuItem*)anItem setState:!self.audioClient.isPlaying];
+        [(NSMenuItem *)anItem setState:!self.audioClient.isPlaying];
     }
     else if ([anItem action] == @selector(togglePause:)) {
-        [(NSMenuItem*)anItem setState:(!running) || (GB_debugger_is_stopped(&gb))];
+        if (master) {
+            [(NSMenuItem *)anItem setState:(!master->running) || (GB_debugger_is_stopped(&gb)) || (GB_debugger_is_stopped(&gb))];
+        }
+        [(NSMenuItem *)anItem setState:(!running) || (GB_debugger_is_stopped(&gb))];
         return !GB_debugger_is_stopped(&gb);
     }
     else if ([anItem action] == @selector(reset:) && anItem.tag != MODEL_NONE) {
@@ -804,6 +893,10 @@ static void rumbleCallback(GB_gameboy_t *gb, double amp)
     else if ([anItem action] == @selector(connectWorkboy:)) {
         [(NSMenuItem*)anItem setState:accessory == GBAccessoryWorkboy];
     }
+    else if ([anItem action] == @selector(connectLinkCable:)) {
+        [(NSMenuItem*)anItem setState:[(NSMenuItem *)anItem representedObject] == master ||
+                                       [(NSMenuItem *)anItem representedObject] == slave];
+    }
     else if ([anItem action] == @selector(toggleCheats:)) {
         [(NSMenuItem*)anItem setState:GB_cheats_enabled(&gb)];
     }
@@ -1090,6 +1183,9 @@ static void rumbleCallback(GB_gameboy_t *gb, double amp)
 {
     while (!GB_is_inited(&gb));
     bool was_running = running && !GB_debugger_is_stopped(&gb);
+    if (master) {
+        was_running |= master->running;
+    }
     if (was_running) {
         [self stop];
     }
@@ -1700,6 +1796,7 @@ static void rumbleCallback(GB_gameboy_t *gb, double amp)
 
 - (IBAction)disconnectAllAccessories:(id)sender
 {
+    [self disconnectLinkCable];
     [self performAtomicBlock:^{
         accessory = GBAccessoryNone;
         GB_disconnect_serial(&gb);
@@ -1708,6 +1805,7 @@ static void rumbleCallback(GB_gameboy_t *gb, double amp)
 
 - (IBAction)connectPrinter:(id)sender
 {
+    [self disconnectLinkCable];
     [self performAtomicBlock:^{
         accessory = GBAccessoryPrinter;
         GB_connect_printer(&gb, printImage);
@@ -1716,6 +1814,7 @@ static void rumbleCallback(GB_gameboy_t *gb, double amp)
 
 - (IBAction)connectWorkboy:(id)sender
 {
+    [self disconnectLinkCable];
     [self performAtomicBlock:^{
         accessory = GBAccessoryWorkboy;
         GB_connect_workboy(&gb, setWorkboyTime, getWorkboyTime);
@@ -1832,4 +1931,83 @@ static void rumbleCallback(GB_gameboy_t *gb, double amp)
 {
     GB_set_cheats_enabled(&gb, !GB_cheats_enabled(&gb));
 }
+
+- (void)disconnectLinkCable
+{
+    bool wasRunning = self->running;
+    Document *partner = master ?: slave;
+    if (partner) {
+        [self stop];
+        partner->master = nil;
+        partner->slave = nil;
+        master = nil;
+        slave = nil;
+        if (wasRunning) {
+            [partner start];
+            [self start];
+        }
+        GB_set_turbo_mode(&gb, false, false);
+        GB_set_turbo_mode(&partner->gb, false, false);
+        partner->accessory = GBAccessoryNone;
+        accessory = GBAccessoryNone;
+    }
+}
+
+- (void)connectLinkCable:(NSMenuItem *)sender
+{
+    [self disconnectAllAccessories:sender];
+    Document *partner = [sender representedObject];
+    [partner disconnectAllAccessories:sender];
+    
+    bool wasRunning = self->running;
+    [self stop];
+    [partner stop];
+    GB_set_turbo_mode(&partner->gb, true, true);
+    slave = partner;
+    partner->master = self;
+    linkOffset = 0;
+    partner->accessory = GBAccessoryLinkCable;
+    accessory = GBAccessoryLinkCable;
+    GB_set_serial_transfer_bit_start_callback(&gb, linkCableBitStart);
+    GB_set_serial_transfer_bit_start_callback(&partner->gb, linkCableBitStart);
+    GB_set_serial_transfer_bit_end_callback(&gb, linkCableBitEnd);
+    GB_set_serial_transfer_bit_end_callback(&partner->gb, linkCableBitEnd);
+    if (wasRunning) {
+        [self start];
+    }
+}
+
+- (void)linkCableBitStart:(bool)bit
+{
+    linkCableBit = bit;
+}
+
+-(bool)linkCableBitEnd
+{
+    bool ret = GB_serial_get_data_bit(&self.partner->gb);
+    GB_serial_set_data_bit(&self.partner->gb, linkCableBit);
+    return ret;
+}
+
+- (void)infraredStateChanged:(bool)state
+{
+    if (self.partner) {
+        GB_set_infrared_input(&self.partner->gb, state);
+    }
+}
+
+-(Document *)partner
+{
+    return slave ?: master;
+}
+
+- (bool)isSlave
+{
+    return master;
+}
+
+- (GB_gameboy_t *)gb
+{
+    return &gb;
+}
 @end

Cocoa/Document.xib

@@ -59,6 +59,9 @@
                             <view fixedFrame="YES" translatesAutoresizingMaskIntoConstraints="NO" id="uqf-pe-VAF" customClass="GBView">
                                 <rect key="frame" x="0.0" y="0.0" width="160" height="144"/>
                                 <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
+                                <connections>
+                                    <outlet property="document" destination="-2" id="Fvh-rD-z4r"/>
+                                </connections>
                             </view>
                         </subviews>
                     </customView>
@@ -115,7 +118,7 @@
                                         <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
                                         <clipView key="contentView" ambiguous="YES" drawsBackground="NO" copiesOnScroll="NO" id="EQe-Ad-L7S">
                                             <rect key="frame" x="0.0" y="0.0" width="591" height="376"/>
-                                            <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
+                                            <autoresizingMask key="autoresizingMask"/>
                                             <subviews>
                                                 <textView ambiguous="YES" editable="NO" drawsBackground="NO" importsGraphics="NO" richText="NO" verticallyResizable="YES" baseWritingDirection="leftToRight" findStyle="bar" allowsNonContiguousLayout="YES" id="doS-dM-hnl">
                                                     <rect key="frame" x="0.0" y="0.0" width="591" height="376"/>
@@ -152,7 +155,7 @@
                                         <autoresizingMask key="autoresizingMask" widthSizable="YES" flexibleMinY="YES"/>
                                         <clipView key="contentView" ambiguous="YES" drawsBackground="NO" copiesOnScroll="NO" id="YHx-TM-zIC">
                                             <rect key="frame" x="0.0" y="0.0" width="329" height="47"/>
-                                            <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
+                                            <autoresizingMask key="autoresizingMask"/>
                                             <subviews>
                                                 <textView ambiguous="YES" drawsBackground="NO" importsGraphics="NO" richText="NO" verticallyResizable="YES" allowsCharacterPickerTouchBarItem="NO" allowsUndo="YES" allowsNonContiguousLayout="YES" textCompletion="NO" spellingCorrection="YES" id="w0g-eK-jM4">
                                                     <rect key="frame" x="0.0" y="0.0" width="329" height="47"/>
@@ -186,7 +189,7 @@
                                         <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
                                         <clipView key="contentView" ambiguous="YES" drawsBackground="NO" copiesOnScroll="NO" id="Cs9-3x-ATg">
                                             <rect key="frame" x="0.0" y="0.0" width="329" height="328"/>
-                                            <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
+                                            <autoresizingMask key="autoresizingMask"/>
                                             <subviews>
                                                 <textView ambiguous="YES" editable="NO" drawsBackground="NO" importsGraphics="NO" richText="NO" verticallyResizable="YES" baseWritingDirection="leftToRight" findStyle="bar" allowsNonContiguousLayout="YES" spellingCorrection="YES" id="JgV-7E-iwp">
                                                     <rect key="frame" x="0.0" y="0.0" width="329" height="328"/>
@@ -975,7 +978,7 @@
                         <autoresizingMask key="autoresizingMask" flexibleMinX="YES" heightSizable="YES"/>
                         <clipView key="contentView" id="mzf-yu-RID">
                             <rect key="frame" x="1" y="0.0" width="398" height="274"/>
-                            <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
+                            <autoresizingMask key="autoresizingMask"/>
                             <subviews>
                                 <tableView verticalHuggingPriority="750" allowsExpansionToolTips="YES" columnAutoresizingStyle="none" alternatingRowBackgroundColors="YES" columnReordering="NO" columnResizing="NO" multipleSelection="NO" emptySelection="NO" autosaveColumns="NO" typeSelect="NO" headerView="pvX-uJ-qK5" id="tA3-8T-bxb">
                                     <rect key="frame" x="0.0" y="0.0" width="398" height="249"/>

Cocoa/GBView.h

@@ -1,6 +1,7 @@
 #import <Cocoa/Cocoa.h>
 #include <Core/gb.h>
 #import <JoyKit/JoyKit.h>
+@class Document;
 
 typedef enum {
     GB_FRAME_BLENDING_MODE_DISABLED,
@@ -13,6 +14,7 @@ typedef enum {
 @interface GBView : NSView<JOYListener>
 - (void) flip;
 - (uint32_t *) pixels;
+@property (weak) IBOutlet Document *document;
 @property GB_gameboy_t *gb;
 @property (nonatomic) GB_frame_blending_mode_t frameBlendingMode;
 @property (getter=isMouseHidingEnabled) BOOL mouseHidingEnabled;

Cocoa/GBView.m

@@ -5,6 +5,7 @@
 #import "GBViewMetal.h"
 #import "GBButtons.h"
 #import "NSString+StringForKey.h"
+#import "Document.h"
 
 #define JOYSTICK_HIGH 0x4000
 #define JOYSTICK_LOW 0x3800
@@ -257,6 +258,9 @@ static const uint8_t workboy_vk_to_key[] = {
 {
     if (analogClockMultiplierValid && [[NSUserDefaults standardUserDefaults] boolForKey:@"GBAnalogControls"]) {
         GB_set_clock_multiplier(_gb, analogClockMultiplier);
+        if (self.document.partner) {
+            GB_set_clock_multiplier(self.document.partner.gb, analogClockMultiplier);
+        }
         if (analogClockMultiplier == 1.0) {
             analogClockMultiplierValid = false;
         }
@@ -265,10 +269,16 @@ static const uint8_t workboy_vk_to_key[] = {
         if (underclockKeyDown && clockMultiplier > 0.5) {
             clockMultiplier -= 1.0/16;
             GB_set_clock_multiplier(_gb, clockMultiplier);
+            if (self.document.partner) {
+                GB_set_clock_multiplier(self.document.partner.gb, clockMultiplier);
+            }
         }
         if (!underclockKeyDown && clockMultiplier < 1.0) {
             clockMultiplier += 1.0/16;
             GB_set_clock_multiplier(_gb, clockMultiplier);
+            if (self.document.partner) {
+                GB_set_clock_multiplier(self.document.partner.gb, clockMultiplier);
+            }
         }
     }
     current_buffer = (current_buffer + 1) % self.numberOfBuffers;
@@ -299,6 +309,9 @@ static const uint8_t workboy_vk_to_key[] = {
 
     NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
     unsigned player_count = GB_get_player_count(_gb);
+    if (self.document.partner) {
+        player_count = 2;
+    }
     for (unsigned player = 0; player < player_count; player++) {
         for (GBButton button = 0; button < GBButtonCount; button++) {
             NSNumber *key = [defaults valueForKey:button_to_preference_name(button, player)];
@@ -308,13 +321,20 @@ static const uint8_t workboy_vk_to_key[] = {
                 handled = true;
                 switch (button) {
                     case GBTurbo:
-                        GB_set_turbo_mode(_gb, true, self.isRewinding);
+                        if (self.document.isSlave) {
+                            GB_set_turbo_mode(self.document.partner.gb, true, false);
+                        }
+                        else {
+                            GB_set_turbo_mode(_gb, true, self.isRewinding);
+                        }
                         analogClockMultiplierValid = false;
                         break;
                         
                     case GBRewind:
-                        self.isRewinding = true;
+                        if (!self.document.partner) {
-                        GB_set_turbo_mode(_gb, false, false);
+                            self.isRewinding = true;
+                            GB_set_turbo_mode(_gb, false, false);
+                        }
                         break;
                         
                     case GBUnderclock:
@@ -323,7 +343,17 @@ static const uint8_t workboy_vk_to_key[] = {
                         break;
                         
                     default:
-                        GB_set_key_state_for_player(_gb, (GB_key_t)button, player, true);
+                        if (self.document.partner) {
+                            if (player == 0) {
+                                GB_set_key_state_for_player(_gb, (GB_key_t)button, 0, true);
+                            }
+                            else {
+                                GB_set_key_state_for_player(self.document.partner.gb, (GB_key_t)button, 0, true);
+                            }
+                        }
+                        else {
+                            GB_set_key_state_for_player(_gb, (GB_key_t)button, player, true);
+                        }
                         break;
                 }
             }
@@ -351,6 +381,9 @@ static const uint8_t workboy_vk_to_key[] = {
 
     NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
     unsigned player_count = GB_get_player_count(_gb);
+    if (self.document.partner) {
+        player_count = 2;
+    }
     for (unsigned player = 0; player < player_count; player++) {
         for (GBButton button = 0; button < GBButtonCount; button++) {
             NSNumber *key = [defaults valueForKey:button_to_preference_name(button, player)];
@@ -360,7 +393,12 @@ static const uint8_t workboy_vk_to_key[] = {
                 handled = true;
                 switch (button) {
                     case GBTurbo:
-                        GB_set_turbo_mode(_gb, false, false);
+                        if (self.document.isSlave) {
+                            GB_set_turbo_mode(self.document.partner.gb, false, false);
+                        }
+                        else {
+                            GB_set_turbo_mode(_gb, false, false);
+                        }
                         analogClockMultiplierValid = false;
                         break;
                         
@@ -374,7 +412,17 @@ static const uint8_t workboy_vk_to_key[] = {
                         break;
                         
                     default:
-                        GB_set_key_state_for_player(_gb, (GB_key_t)button, player, false);
+                        if (self.document.partner) {
+                            if (player == 0) {
+                                GB_set_key_state_for_player(_gb, (GB_key_t)button, 0, false);
+                            }
+                            else {
+                                GB_set_key_state_for_player(self.document.partner.gb, (GB_key_t)button, 0, false);
+                            }
+                        }
+                        else {
+                            GB_set_key_state_for_player(_gb, (GB_key_t)button, player, false);
+                        }
                         break;
                 }
             }
@@ -415,13 +463,11 @@ static const uint8_t workboy_vk_to_key[] = {
 - (void)controller:(JOYController *)controller buttonChangedState:(JOYButton *)button
 {
     if (![self.window isMainWindow]) return;
-    if (controller != lastController) {
-        [self setRumble:0];
-        lastController = controller;
-    }
-    
     
     unsigned player_count = GB_get_player_count(_gb);
+    if (self.document.partner) {
+        player_count = 2;
+    }
 
     IOPMAssertionID assertionID;
     IOPMAssertionDeclareUserActivity(CFSTR(""), kIOPMUserActiveLocal, &assertionID);
@@ -447,33 +493,63 @@ static const uint8_t workboy_vk_to_key[] = {
             usage = (const JOYButtonUsage[]){JOYButtonUsageY, JOYButtonUsageA, JOYButtonUsageB, JOYButtonUsageX}[(usage - JOYButtonUsageGeneric0) & 3];
         }
         
+        GB_gameboy_t *effectiveGB = _gb;
+        unsigned effectivePlayer = player;
+        
+        if (player && self.document.partner) {
+            effectiveGB = self.document.partner.gb;
+            effectivePlayer = 0;
+            if (controller != self.document.partner.view->lastController) {
+                [self setRumble:0];
+                self.document.partner.view->lastController = controller;
+            }
+        }
+        else {
+            if (controller != lastController) {
+                [self setRumble:0];
+                lastController = controller;
+            }
+        }
+        
         switch (usage) {
                 
             case JOYButtonUsageNone: break;
-            case JOYButtonUsageA: GB_set_key_state_for_player(_gb, GB_KEY_A, player, button.isPressed); break;
+            case JOYButtonUsageA: GB_set_key_state_for_player(effectiveGB, GB_KEY_A, effectivePlayer, button.isPressed); break;
-            case JOYButtonUsageB: GB_set_key_state_for_player(_gb, GB_KEY_B, player, button.isPressed); break;
+            case JOYButtonUsageB: GB_set_key_state_for_player(effectiveGB, GB_KEY_B, effectivePlayer, button.isPressed); break;
             case JOYButtonUsageC: break;
             case JOYButtonUsageStart:
-            case JOYButtonUsageX: GB_set_key_state_for_player(_gb, GB_KEY_START, player, button.isPressed); break;
+            case JOYButtonUsageX: GB_set_key_state_for_player(effectiveGB, GB_KEY_START, effectivePlayer, button.isPressed); break;
             case JOYButtonUsageSelect:
-            case JOYButtonUsageY: GB_set_key_state_for_player(_gb, GB_KEY_SELECT, player, button.isPressed); break;
+            case JOYButtonUsageY: GB_set_key_state_for_player(effectiveGB, GB_KEY_SELECT, effectivePlayer, button.isPressed); break;
             case JOYButtonUsageR2:
             case JOYButtonUsageL2:
             case JOYButtonUsageZ: {
                 self.isRewinding = button.isPressed;
                 if (button.isPressed) {
-                    GB_set_turbo_mode(_gb, false, false);
+                    if (self.document.isSlave) {
+                        GB_set_turbo_mode(self.document.partner.gb, false, false);
+                    }
+                    else {
+                        GB_set_turbo_mode(_gb, false, false);
+                    }
                 }
                 break;
             }
         
-            case JOYButtonUsageL1: GB_set_turbo_mode(_gb, button.isPressed, button.isPressed && self.isRewinding); break;
+            case JOYButtonUsageL1: {
+                if (self.document.isSlave) {
+                    GB_set_turbo_mode(self.document.partner.gb, button.isPressed, false); break;
+                }
+                else {
+                    GB_set_turbo_mode(_gb, button.isPressed, button.isPressed && self.isRewinding); break;
+                }
+            }
 
             case JOYButtonUsageR1: underclockKeyDown = button.isPressed; break;
-            case JOYButtonUsageDPadLeft: GB_set_key_state_for_player(_gb, GB_KEY_LEFT, player, button.isPressed); break;
+            case JOYButtonUsageDPadLeft: GB_set_key_state_for_player(effectiveGB, GB_KEY_LEFT, effectivePlayer, button.isPressed); break;
-            case JOYButtonUsageDPadRight: GB_set_key_state_for_player(_gb, GB_KEY_RIGHT, player, button.isPressed); break;
+            case JOYButtonUsageDPadRight: GB_set_key_state_for_player(effectiveGB, GB_KEY_RIGHT, effectivePlayer, button.isPressed); break;
-            case JOYButtonUsageDPadUp: GB_set_key_state_for_player(_gb, GB_KEY_UP, player, button.isPressed); break;
+            case JOYButtonUsageDPadUp: GB_set_key_state_for_player(effectiveGB, GB_KEY_UP, effectivePlayer, button.isPressed); break;
-            case JOYButtonUsageDPadDown: GB_set_key_state_for_player(_gb, GB_KEY_DOWN, player, button.isPressed); break;
+            case JOYButtonUsageDPadDown: GB_set_key_state_for_player(effectiveGB, GB_KEY_DOWN, effectivePlayer, button.isPressed); break;
 
             default:
                 break;

Cocoa/MainMenu.xib

@@ -12,7 +12,11 @@
         </customObject>
         <customObject id="-1" userLabel="First Responder" customClass="FirstResponder"/>
         <customObject id="-3" userLabel="Application" customClass="NSObject"/>
-        <customObject id="Voe-Tx-rLC" customClass="AppDelegate"/>
+        <customObject id="Voe-Tx-rLC" customClass="AppDelegate">
+            <connections>
+                <outlet property="linkCableMenuItem" destination="V4S-Fo-xJK" id="KL9-3K-64i"/>
+            </connections>
+        </customObject>
         <customObject id="YLy-65-1bz" customClass="NSFontManager"/>
         <menu title="Main Menu" systemMenu="main" id="AYu-sK-qS6">
             <items>
@@ -373,6 +377,17 @@
                                     <action selector="disconnectAllAccessories:" target="-1" id="5hY-9U-nRn"/>
                                 </connections>
                             </menuItem>
+                            <menuItem title="Game Link Cable &amp; Infrared" id="V4S-Fo-xJK">
+                                <modifierMask key="keyEquivalentModifierMask"/>
+                                <menu key="submenu" title="Game Link Cable &amp; Infrared" id="6sJ-Wz-QLj">
+                                    <connections>
+                                        <outlet property="delegate" destination="Voe-Tx-rLC" id="PMY-5j-25T"/>
+                                    </connections>
+                                </menu>
+                                <connections>
+                                    <action selector="nop:" target="Voe-Tx-rLC" id="Bpa-0C-lkN"/>
+                                </connections>
+                            </menuItem>
                             <menuItem title="Game Boy Printer" id="zHR-Ha-pOR">
                                 <modifierMask key="keyEquivalentModifierMask"/>
                                 <connections>

Core/gb.h

@@ -803,9 +803,7 @@ void GB_set_icd_pixel_callback(GB_gameboy_t *gb, GB_icd_pixel_callback_t callbac
 void GB_set_icd_hreset_callback(GB_gameboy_t *gb, GB_icd_hreset_callback_t callback);
 void GB_set_icd_vreset_callback(GB_gameboy_t *gb, GB_icd_vreset_callback_t callback);
     
-#ifdef GB_INTERNAL
 uint32_t GB_get_clock_rate(GB_gameboy_t *gb);
-#endif
 void GB_set_clock_multiplier(GB_gameboy_t *gb, double multiplier);
 
 unsigned GB_get_screen_width(GB_gameboy_t *gb);