Sprinkle `const` around where appropriate (#1909)

* Sprinkle `const` around where appropriate

- This will make it easier to use `NDS` objects in `const` contexts (e.g. `const` parameters or methods)

* Remove the `const` qualifier on `DSi_DSP::DSPRead16`

- MMIO reads can be non-pure, so this may not be `const` in the future

1 files changed, 4 insertions, 4 deletions

diff --git a/src/GPU2D.h b/src/GPU2D.h
index 7367d07..e87167c 100644
--- a/src/GPU2D.h
+++ b/src/GPU2D.h
@@ -52,7 +52,7 @@ public:
     void Write16(u32 addr, u16 val);
     void Write32(u32 addr, u32 val);
 
-    bool UsesFIFO()
+    bool UsesFIFO() const
     {
         if (((DispCnt >> 16) & 0x3) == 3)
             return true;
@@ -72,11 +72,11 @@ public:
     u16* GetBGExtPal(u32 slot, u32 pal);
     u16* GetOBJExtPal();
 
-    void GetBGVRAM(u8*& data, u32& mask);
-    void GetOBJVRAM(u8*& data, u32& mask);
+    void GetBGVRAM(u8*& data, u32& mask) const;
+    void GetOBJVRAM(u8*& data, u32& mask) const;
 
     void UpdateMosaicCounters(u32 line);
-    void CalculateWindowMask(u32 line, u8* windowMask, u8* objWindow);
+    void CalculateWindowMask(u32 line, u8* windowMask, const u8* objWindow);
 
     u32 Num;
     bool Enabled;