begin work on proper multiplayer UI shito.

for now, determine a global instance ID, and derivate the system MAC from it. remove 'randomize MAC' option.

src/frontend/qt_sdl/LocalMP.cpp

@@ -235,7 +235,7 @@ void SemReset(int num)
 
 bool Init()
 {
-    MPQueue = new QSharedMemory("melonNIFI_FIFO");
+    MPQueue = new QSharedMemory("melonNIFI");
 
     if (!MPQueue->attach())
     {

src/frontend/qt_sdl/Platform.cpp

@@ -28,6 +28,7 @@
 #include <QSemaphore>
 #include <QMutex>
 #include <QOpenGLContext>
+#include <QSharedMemory>
 
 #include "Platform.h"
 #include "Config.h"
@@ -44,6 +45,55 @@ void emuStop();
 namespace Platform
 {
 
+QSharedMemory* IPCBuffer = nullptr;
+int IPCInstanceID;
+
+void IPCInit()
+{
+    IPCInstanceID = 0;
+
+    IPCBuffer = new QSharedMemory("melonIPC");
+
+    if (!IPCBuffer->attach())
+    {
+        printf("IPC sharedmem doesn't exist. creating\n");
+        if (!IPCBuffer->create(4096))
+        {
+            printf("IPC sharedmem create failed :(\n");
+            delete IPCBuffer;
+            IPCBuffer= nullptr;
+            return;
+        }
+
+        IPCBuffer->lock();
+        memset(IPCBuffer->data(), 0, IPCBuffer->size());
+        IPCBuffer->unlock();
+    }
+
+    IPCBuffer->lock();
+    u8* data = (u8*)IPCBuffer->data();
+    u16 mask = *(u16*)&data[0];
+    for (int i = 0; i < 16; i++)
+    {
+        if (!(mask & (1<<i)))
+        {
+            IPCInstanceID = i;
+            *(u16*)&data[0] |= (1<<i);
+            break;
+        }
+    }
+    IPCBuffer->unlock();
+
+    printf("IPC: instance ID %d\n", IPCInstanceID);
+}
+
+void IPCDeInit()
+{
+    if (IPCBuffer) delete IPCBuffer;
+    IPCBuffer = nullptr;
+}
+
+
 void Init(int argc, char** argv)
 {
 #if defined(__WIN32__) || defined(PORTABLE)
@@ -77,10 +127,13 @@ void Init(int argc, char** argv)
     confdir = config.absolutePath() + "/melonDS/";
     EmuDirectory = confdir.toStdString();
 #endif
+
+    IPCInit();
 }
 
 void DeInit()
 {
+    IPCDeInit();
 }
 
 
@@ -90,6 +143,12 @@ void StopEmu()
 }
 
 
+int InstanceID()
+{
+    return IPCInstanceID;
+}
+
+
 int GetConfigInt(ConfigEntry entry)
 {
     const int imgsizes[] = {0, 256, 512, 1024, 2048, 4096};

src/frontend/qt_sdl/main.cpp

@@ -647,7 +647,11 @@ void EmuThread::run()
                 if (winUpdateFreq < 1)
                     winUpdateFreq = 1;
 
-                sprintf(melontitle, "[%d/%.0f] melonDS " MELONDS_VERSION, fps, fpstarget);
+                int inst = Platform::InstanceID();
+                if (inst == 0)
+                    sprintf(melontitle, "[%d/%.0f] melonDS " MELONDS_VERSION, fps, fpstarget);
+                else
+                    sprintf(melontitle, "[%d/%.0f] melonDS (%d)", fps, fpstarget, inst+1);
                 changeWindowTitle(melontitle);
             }
         }
@@ -662,7 +666,11 @@ void EmuThread::run()
 
             EmuStatus = EmuRunning;
 
-            sprintf(melontitle, "melonDS " MELONDS_VERSION);
+            int inst = Platform::InstanceID();
+            if (inst == 0)
+                sprintf(melontitle, "melonDS " MELONDS_VERSION);
+            else
+                sprintf(melontitle, "melonDS (%d)", inst+1);
             changeWindowTitle(melontitle);
 
             SDL_Delay(75);