* start GPU shit: draw BG0 16-color.

* fix a few DMA bugs.
* fix a bug where some code could still run right after a halt instruction.
* fix VRAM mapping, too. I'm an idiot.

GPU2D.h

@@ -41,6 +41,12 @@ public:
 private:
     u32 Num;
     u16* Framebuffer;
+
+    u32 DispCnt;
+    u16 BGCnt[4];
+
+    void DrawScanline_Mode1(u32 line, u16* dst);
+    void DrawBG_Text_4bpp(u32 line, u16* dst, u32 num);
 };
 
 #endif