Add support for Slot 2 flashcarts using Compact Flash (#84)

- Supercard CF (SUPERCARDCF)
- GBA Media Player CF (MPCF)
- M3 Adapter CF (M3CF)
- Max Media Dock CF (MMCF)

arm9/source/patches/platform/m3cf/M3CFLoaderPlatform.cpp

@@ -0,0 +1,41 @@
+#include "common.h"
+#include "M3CFLoaderPlatform.h"
+
+#define M3_MODE_ROM 8
+#define M3_MODE_MEDIA 6
+
+static u16 volatileReadHalfword(u32 addr)
+{
+    return *((vu16*)addr);
+}
+
+static void changeM3Mode(u32 mode)
+{
+    volatileReadHalfword(0x08e00002);
+    volatileReadHalfword(0x0800000e);
+    volatileReadHalfword(0x08801FFC);
+    volatileReadHalfword(0x0800104A);
+    volatileReadHalfword(0x08800612);
+    volatileReadHalfword(0x08000000);
+    volatileReadHalfword(0x08801B66);
+    volatileReadHalfword(0x08800000 + mode);
+    volatileReadHalfword(0x0800080E);
+    volatileReadHalfword(0x08000000);
+    
+    if(mode == M3_MODE_ROM)
+    {
+        volatileReadHalfword(0x080001E4);
+        volatileReadHalfword(0x080001E4);
+        volatileReadHalfword(0x08000188);
+        volatileReadHalfword(0x08000188);
+    }
+    else
+    {
+        volatileReadHalfword(0x09000000);
+    }
+}
+
+void M3CFLoaderPlatform::SetCardLocked(bool locked) const
+{
+    changeM3Mode(locked ? M3_MODE_ROM : M3_MODE_MEDIA);
+}