@@ -19,6 +19,12 @@ static Uint8 blending[5][16] = {

 	{2, 3, 1, 2, 2, 3, 1, 2, 2, 3, 1, 2, 2, 3, 1, 2},

 	{1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 0, 1, 1, 1, 1, 0}};

+static Uint16

+ppu_row(Ppu *p, Uint16 x, Uint16 y)

+{

+	return (y % 8) + ((x / 8 + y / 8 * p->width / 8) * 16);

+}

+

 static void

 ppu_clear(Ppu *p)

 {

@@ -34,12 +40,12 @@ ppu_clear(Ppu *p)

 Uint8

 ppu_read(Ppu *p, Uint16 x, Uint16 y)

 {

-	int ch1, ch2, r = (y % 8) + ((x / 8 + y / 8 * p->width / 8) * 16);

-	ch1 = (p->fg[r] >> (7 - x % 8)) & 1;

-	ch2 = (p->fg[r + 8] >> (7 - x % 8)) & 1;

+	Uint16 ch1, ch2, row = ppu_row(p, x, y);

+	ch1 = (p->fg[row] >> (7 - x % 8)) & 1;

+	ch2 = (p->fg[row + 8] >> (7 - x % 8)) & 1;

 	if(!ch1 && !ch2) {

-		ch1 = (p->bg[r] >> (7 - x % 8)) & 1;

-		ch2 = (p->bg[r + 8] >> (7 - x % 8)) & 1;

+		ch1 = (p->bg[row] >> (7 - x % 8)) & 1;

+		ch2 = (p->bg[row + 8] >> (7 - x % 8)) & 1;

 	}

 	return ch1 + (ch2 << 1);

 }

@@ -47,17 +53,17 @@ ppu_read(Ppu *p, Uint16 x, Uint16 y)

 void

 ppu_write(Ppu *p, Uint8 *layer, Uint16 x, Uint16 y, Uint8 color)

 {

-	int row = (y % 8) + ((x / 8 + y / 8 * p->width / 8) * 16), col = x % 8;

+	Uint16 row = ppu_row(p, x, y), col = 7 - (x % 8);

 	if(x >= p->width || y >= p->height)

 		return;

 	if(color == 0 || color == 2)

-		layer[row] &= ~(1UL << (7 - col));

+		layer[row] &= ~(1UL << col);

 	else

-		layer[row] |= 1UL << (7 - col);

+		layer[row] |= 1UL << col;

 	if(color == 0 || color == 1)

-		layer[row + 8] &= ~(1UL << (7 - col));

+		layer[row + 8] &= ~(1UL << col);

 	else

-		layer[row + 8] |= 1UL << (7 - col);

+		layer[row + 8] |= 1UL << col;

 }

 void