lay base for IPC work

src/frontend/qt_sdl/IPC.cpp

@@ -0,0 +1,88 @@
+/*
+    Copyright 2016-2022 melonDS team
+
+    This file is part of melonDS.
+
+    melonDS is free software: you can redistribute it and/or modify it under
+    the terms of the GNU General Public License as published by the Free
+    Software Foundation, either version 3 of the License, or (at your option)
+    any later version.
+
+    melonDS is distributed in the hope that it will be useful, but WITHOUT ANY
+    WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+    FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License along
+    with melonDS. If not, see http://www.gnu.org/licenses/.
+*/
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <QSharedMemory>
+
+#include "IPC.h"
+
+
+namespace IPC
+{
+
+QSharedMemory* Buffer = nullptr;
+int InstanceID;
+
+
+void Init()
+{
+    InstanceID = 0;
+
+    Buffer = new QSharedMemory("melonIPC");
+
+    if (!Buffer->attach())
+    {
+        printf("IPC sharedmem doesn't exist. creating\n");
+        if (!Buffer->create(1024))
+        {
+            printf("IPC sharedmem create failed :(\n");
+            delete Buffer;
+            Buffer = nullptr;
+            return;
+        }
+
+        Buffer->lock();
+        memset(Buffer->data(), 0, Buffer->size());
+        Buffer->unlock();
+    }
+
+    Buffer->lock();
+    u8* data = (u8*)Buffer->data();
+    u16 mask = *(u16*)&data[0];
+    for (int i = 0; i < 16; i++)
+    {
+        if (!(mask & (1<<i)))
+        {
+            InstanceID = i;
+            *(u16*)&data[0] |= (1<<i);
+            break;
+        }
+    }
+    Buffer->unlock();
+
+    printf("IPC: instance ID %d\n", InstanceID);
+}
+
+void DeInit()
+{
+    if (Buffer)
+    {
+        Buffer->lock();
+        u8* data = (u8*)Buffer->data();
+        *(u16*)&data[0] &= ~(1<<InstanceID);
+        Buffer->unlock();
+
+        Buffer->detach();
+        delete Buffer;
+    }
+    Buffer = nullptr;
+}
+
+}