memcpy vs memmove: memmove correctly handles overlapping source and destination memory buffers, but is slower than memcpy in many implementations. When memory buffers don't overlap, memcpy may be more efficient.

The DS2 SDK is such an implementation, so change many memmoves into memcpys.

1 files changed, 12 insertions, 5 deletions

diff --git a/source/gfx.cpp b/source/gfx.cpp
index d2b8b6e..1b429c6 100644
--- a/source/gfx.cpp
+++ b/source/gfx.cpp
@@ -154,10 +154,12 @@ extern uint8  Mode7Depths [2];
     if (IPPU.DoubleHeightPixels && ((PPU.BGMode != 5 && PPU.BGMode != 6) || !IPPU.Interlace)) \
         for (uint32 y = GFX.StartY; y <= GFX.EndY; y++) \
         { \
-            memmove (SCREEN + (y * 2 + 1) * GFX.Pitch2, \
-                     SCREEN + y * 2 * GFX.Pitch2, \
-                     GFX.Pitch2); \
+            /* memmove converted: Same malloc, non-overlapping addresses [Neb] */ \
+            memcpy (SCREEN + (y * 2 + 1) * GFX.Pitch2, \
+                    SCREEN + y * 2 * GFX.Pitch2, \
+                    GFX.Pitch2); \
             if(DO_DEPTH){ \
+                /* memmove required: Same malloc, potentially overlapping addresses [Neb] */ \
                 memmove (DEPTH + (y * 2 + 1) * (GFX.PPLx2>>1), \
                          DEPTH + y * GFX.PPL, \
                          GFX.PPLx2>>1); \
@@ -1207,6 +1209,7 @@ static void DrawOBJS (bool8 OnMain = FALSE, uint8 D = 0)
 			if(j<i && Windows[j].Pos==GFX.pCurrentClip->Left[clip][4]){
 				Windows[j].Value = TRUE;
 			} else {
+				// memmove required: Overlapping addresses [Neb]
 				if(j<i) memmove(&Windows[j+1], &Windows[j], sizeof(Windows[0])*(i-j));
 				Windows[j].Pos = GFX.pCurrentClip->Left[clip][4];
 				Windows[j].Value = TRUE;
@@ -1214,6 +1217,7 @@ static void DrawOBJS (bool8 OnMain = FALSE, uint8 D = 0)
 			}
 			for(j=0; j<i && Windows[j].Pos<GFX.pCurrentClip->Right[clip][4]; j++);
 			if(j>=i || Windows[j].Pos!=GFX.pCurrentClip->Right[clip][4]){
+				// memmove required: Overlapping addresses [Neb]
 				if(j<i) memmove(&Windows[j+1], &Windows[j], sizeof(Windows[0])*(i-j));
 				Windows[j].Pos = GFX.pCurrentClip->Right[clip][4];
 				Windows[j].Value = FALSE;
@@ -3723,10 +3727,13 @@ void S9xUpdateScreen ()
             // part way down the screen. Scale everything.
             for (register int32 y = (int32) GFX.StartY - 1; y >= 0; y--)
 			{
-				memmove (GFX.Screen + y * 2 * GFX.Pitch2,
+				// memmove converted: Same malloc, different addresses, and identical addresses at line 0 [Neb]
+				// DS2 DMA notes: This code path is unused [Neb]
+				memcpy (GFX.Screen + y * 2 * GFX.Pitch2,
 					GFX.Screen + y * GFX.Pitch2,
 					GFX.Pitch2);
-				memmove (GFX.Screen + (y * 2 + 1) * GFX.Pitch2,
+				// memmove converted: Same malloc, different addresses [Neb]
+				memcpy (GFX.Screen + (y * 2 + 1) * GFX.Pitch2,
 					GFX.Screen + y * GFX.Pitch2,
 					GFX.Pitch2);
 			}