Dariaceli's Git
Browse code

Do not overdraw

neauoire authored on 01/10/2021 02:35:22
Showing 1 changed files
src/devices/ppu.c
History View file @ 243c586
... ... 
@@ -41,26 +41,31 @@ ppu_set_size(Ppu *p, Uint16 width, Uint16 height)
41 41 
 Uint8
42 42 
 ppu_read(Ppu *p, Uint16 x, Uint16 y)
43 43 
 {
44 
-	Uint32 row = (x + y * p->width) / 0x2;
45 
-	Uint8 shift = !(x & 0x1) << 2;
46 
-	Uint8 pix = p->pixels[row] >> shift;
47 
-	if(pix & 0x0c)
48 
-		pix = pix >> 2;
49 
-	return pix & 0x3;
44 
+	if(x < p->width && y < p->height) {
45 
+		Uint32 row = (x + y * p->width) / 0x2;
46 
+		Uint8 shift = !(x & 0x1) << 2;
47 
+		Uint8 pix = p->pixels[row] >> shift;
48 
+		if(pix & 0x0c)
49 
+			pix = pix >> 2;
50 
+		return pix & 0x3;
51 
+	}
52 
+	return 0x0;
50 53 
 }
51 54
52 55 
 void
53 56 
 ppu_write(Ppu *p, Uint8 layer, Uint16 x, Uint16 y, Uint8 color)
54 57 
 {
55 
-	Uint32 row = (x + y * p->width) / 0x2;
56 
-	Uint8 shift = (!(x & 0x1) << 2) + (layer << 1);
57 
-	Uint8 pix = p->pixels[row];
58 
-	Uint8 mask = ~(0x3 << shift);
59 
-	Uint8 pixnew = (pix & mask) + (color << shift);
60 
-	if(x < p->width && y < p->height)
61 
-		p->pixels[row] = pixnew;
62 
-	if(pix != pixnew)
63 
-		p->reqdraw = 1;
58 
+	if(x < p->width && y < p->height) {
59 
+		Uint32 row = (x + y * p->width) / 0x2;
60 
+		Uint8 shift = (!(x & 0x1) << 2) + (layer << 1);
61 
+		Uint8 pix = p->pixels[row];
62 
+		Uint8 mask = ~(0x3 << shift);
63 
+		Uint8 pixnew = (pix & mask) + (color << shift);
64 
+		if(x < p->width && y < p->height)
65 
+			p->pixels[row] = pixnew;
66 
+		if(pix != pixnew)
67 
+			p->reqdraw = 1;
68 
+	}
64 69 
 }
65 70
66 71 
 void