@@ -19,48 +19,49 @@ 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}};

-void

-ppu_frame(Ppu *p)

-{

-	p->reqdraw = 0;

-	p->i0 = p->width / PPW + p->height * p->stride;

-	p->i1 = 0;

-}

-

 static void

 ppu_clear(Ppu *p)

 {

-	unsigned int i;

-	for(i = 0; i < p->stride * p->height; ++i)

-		p->dat[i] = 0;

+	int x, y;

+	for(y = 0; y < p->height; ++y) {

+		for(x = 0; x < p->width; ++x) {

+			ppu_write(p, p->bg, x, y, 0);

+			ppu_write(p, p->fg, x, y, 0);

+		}

+	}

 }

 Uint8

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

 {

-	unsigned int i = x / PPW + y * p->stride, shift = x % PPW * 4;

-	return (p->dat[i] >> shift) & 0xf;

+	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;

+	if(!ch1 && !ch2) {

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

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

+	}

+	return ch1 + (ch2 << 1);

 }

 void

-ppu_write(Ppu *p, int fg, Uint16 x, Uint16 y, Uint8 color)

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

 {

-	unsigned int v, i = x / PPW + y * p->stride, shift = x % PPW * 4;

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

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

 		return;

-	v = p->dat[i];

-	if(fg) shift += 2;

-	p->dat[i] &= ~(3 << shift);

-	p->dat[i] |= color << shift;

-	if((v ^ p->dat[i]) != 0) {

-		p->reqdraw = 1;

-		p->i0 = p->i0 < i ? p->i0 : i;

-		p->i1 = p->i1 > i ? p->i1 : i;

-	}

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

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

+	else

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

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

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

+	else

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

 }

 void

-ppu_1bpp(Ppu *p, int fg, Uint16 x, Uint16 y, Uint8 *sprite, Uint8 color, Uint8 flipx, Uint8 flipy)

+ppu_1bpp(Ppu *p, Uint8 *layer, Uint16 x, Uint16 y, Uint8 *sprite, Uint8 color, Uint8 flipx, Uint8 flipy)

 {

 	Uint16 v, h;

 	for(v = 0; v < 8; v++)

@@ -68,7 +69,7 @@ ppu_1bpp(Ppu *p, int fg, Uint16 x, Uint16 y, Uint8 *sprite, Uint8 color, Uint8 f

 			Uint8 ch1 = (sprite[v] >> (7 - h)) & 0x1;

 			if(ch1 || blending[4][color])

 				ppu_write(p,

-					fg,

+					layer,

 					x + (flipx ? 7 - h : h),

 					y + (flipy ? 7 - v : v),

 					blending[ch1][color]);

@@ -76,7 +77,7 @@ ppu_1bpp(Ppu *p, int fg, Uint16 x, Uint16 y, Uint8 *sprite, Uint8 color, Uint8 f

 }

 void

-ppu_2bpp(Ppu *p, int fg, Uint16 x, Uint16 y, Uint8 *sprite, Uint8 color, Uint8 flipx, Uint8 flipy)

+ppu_2bpp(Ppu *p, Uint8 *layer, Uint16 x, Uint16 y, Uint8 *sprite, Uint8 color, Uint8 flipx, Uint8 flipy)

 {

 	Uint16 v, h;

 	for(v = 0; v < 8; v++)

@@ -86,7 +87,7 @@ ppu_2bpp(Ppu *p, int fg, Uint16 x, Uint16 y, Uint8 *sprite, Uint8 color, Uint8 f

 			Uint8 ch = ch1 + ch2 * 2;

 			if(ch || blending[4][color])

 				ppu_write(p,

-					fg,

+					layer,

 					x + (flipx ? 7 - h : h),

 					y + (flipy ? 7 - v : v),

 					blending[ch][color]);

@@ -98,12 +99,12 @@ ppu_2bpp(Ppu *p, int fg, Uint16 x, Uint16 y, Uint8 *sprite, Uint8 color, Uint8 f

 int

 ppu_set_size(Ppu *p, Uint16 width, Uint16 height)

 {

+	ppu_clear(p);

 	p->width = width;

-	p->stride = (width + PPW - 1) / PPW;

 	p->height = height;

-	p->dat = realloc(p->dat, p->stride * p->height * sizeof(unsigned int));

-	if(p->dat == NULL) return 0;

+	p->pixels = realloc(p->bg, p->width / 4 * p->height * sizeof(Uint8) * 2);

+	p->bg = p->pixels;

+	p->fg = p->pixels + (p->width / 4 * p->height * sizeof(Uint8));

 	ppu_clear(p);

-	ppu_frame(p);

-	return 1;

+	return p->bg && p->fg;

 }

@@ -22,14 +22,14 @@ typedef unsigned short Uint16;

 typedef unsigned int Uint32;

 typedef struct Ppu {

-	Uint8 reqdraw;

+	Uint8 *bg, *fg, *pixels, reqdraw;

 	Uint16 width, height;

-	unsigned int i0, i1, *dat, stride;

 } Ppu;

 Uint8 ppu_read(Ppu *p, Uint16 x, Uint16 y);

-void ppu_write(Ppu *p, int fg, Uint16 x, Uint16 y, Uint8 color);

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

 void ppu_frame(Ppu *p);

-void ppu_1bpp(Ppu *p, int fg, Uint16 x, Uint16 y, Uint8 *sprite, Uint8 color, Uint8 flipx, Uint8 flipy);

-void ppu_2bpp(Ppu *p, int fg, Uint16 x, Uint16 y, Uint8 *sprite, Uint8 color, Uint8 flipx, Uint8 flipy);

+

+void ppu_1bpp(Ppu *p, Uint8 *layer, Uint16 x, Uint16 y, Uint8 *sprite, Uint8 color, Uint8 flipx, Uint8 flipy);

+void ppu_2bpp(Ppu *p, Uint8 *layer, Uint16 x, Uint16 y, Uint8 *sprite, Uint8 color, Uint8 flipx, Uint8 flipy);

 int ppu_set_size(Ppu *p, Uint16 width, Uint16 height);

@@ -37,7 +37,7 @@ static SDL_Rect gRect;

 static Ppu ppu;

 static Apu apu[POLYPHONY];

 static Device *devsystem, *devscreen, *devmouse, *devctrl, *devaudio0, *devconsole;

-static Uint8 zoom = 1, reqdraw = 0;

+static Uint8 zoom = 1;

 static Uint32 *ppu_screen, stdin_event, audio0_event, palette[16];

 static Uint8 font[][8] = {

@@ -118,14 +118,14 @@ set_palette(Uint8 *addr)

 	}

 	for(i = 4; i < 16; ++i)

 		palette[i] = palette[i / 4];

-	reqdraw = 1;

+	ppu.reqdraw = 1;

 }

 static void

 set_inspect(Uint8 flag)

 {

 	devsystem->dat[0xe] = flag;

-	reqdraw = 1;

+	ppu.reqdraw = 1;

 }

 static void

@@ -144,7 +144,7 @@ set_zoom(Uint8 scale)

 	if(scale == zoom || !gWindow)

 		return;

 	set_window_size(gWindow, (ppu.width + PAD * 2) * zoom, (ppu.height + PAD * 2) * zoom);

-	reqdraw = 1;

+	ppu.reqdraw = 1;

 }

 static int

@@ -165,7 +165,7 @@ set_size(Uint16 width, Uint16 height, int is_resize)

 		return error("sdl_texture", SDL_GetError());

 	if(is_resize)

 		set_window_size(gWindow, (ppu.width + PAD * 2) * zoom, (ppu.height + PAD * 2) * zoom);

-	reqdraw = 1;

+	ppu.reqdraw = 1;

 	return 1;

 }

@@ -190,51 +190,46 @@ static void

 draw_inspect(Ppu *p, Uint8 *stack, Uint8 wptr, Uint8 rptr, Uint8 *memory)

 {

 	Uint8 i, x, y, b;

-	for(i = 0; i < 0x20; ++i) { /* stack */

+

+	for(i = 0; i < 0x20; ++i) {

 		x = ((i % 8) * 3 + 1) * 8, y = (i / 8 + 1) * 8, b = stack[i];

-		ppu_1bpp(p, 1, x, y, font[(b >> 4) & 0xf], 1 + (wptr == i) * 0x7, 0, 0);

-		ppu_1bpp(p, 1, x + 8, y, font[b & 0xf], 1 + (wptr == i) * 0x7, 0, 0);

+		/* working stack */

+		ppu_1bpp(p, ppu.fg, x, y, font[(b >> 4) & 0xf], 1 + (wptr == i) * 0x7, 0, 0);

+		ppu_1bpp(p, ppu.fg, x + 8, y, font[b & 0xf], 1 + (wptr == i) * 0x7, 0, 0);

+		y = 0x28 + (i / 8 + 1) * 8;

+		b = memory[i];

+		/* return stack */

+		ppu_1bpp(p, ppu.fg, x, y, font[(b >> 4) & 0xf], 3, 0, 0);

+		ppu_1bpp(p, ppu.fg, x + 8, y, font[b & 0xf], 3, 0, 0);

 	}

 	/* return pointer */

-	ppu_1bpp(p, 1, 0x8, y + 0x10, font[(rptr >> 4) & 0xf], 0x2, 0, 0);

-	ppu_1bpp(p, 1, 0x10, y + 0x10, font[rptr & 0xf], 0x2, 0, 0);

-	for(i = 0; i < 0x20; ++i) { /* memory */

-		x = ((i % 8) * 3 + 1) * 8, y = 0x38 + (i / 8 + 1) * 8, b = memory[i];

-		ppu_1bpp(p, 1, x, y, font[(b >> 4) & 0xf], 3, 0, 0);

-		ppu_1bpp(p, 1, x + 8, y, font[b & 0xf], 3, 0, 0);

-	}

-	for(x = 0; x < 0x10; ++x) { /* guides */

-		ppu_write(p, 1, x, p->height / 2, 2);

-		ppu_write(p, 1, p->width - x, p->height / 2, 2);

-		ppu_write(p, 1, p->width / 2, p->height - x, 2);

-		ppu_write(p, 1, p->width / 2, x, 2);

-		ppu_write(p, 1, p->width / 2 - 0x10 / 2 + x, p->height / 2, 2);

-		ppu_write(p, 1, p->width / 2, p->height / 2 - 0x10 / 2 + x, 2);

+	ppu_1bpp(p, ppu.fg, 0x8, y + 0x10, font[(rptr >> 4) & 0xf], 0x2, 0, 0);

+	ppu_1bpp(p, ppu.fg, 0x10, y + 0x10, font[rptr & 0xf], 0x2, 0, 0);

+	/* guides */

+	for(x = 0; x < 0x10; ++x) {

+		ppu_write(p, ppu.fg, x, p->height / 2, 2);

+		ppu_write(p, ppu.fg, p->width - x, p->height / 2, 2);

+		ppu_write(p, ppu.fg, p->width / 2, p->height - x, 2);

+		ppu_write(p, ppu.fg, p->width / 2, x, 2);

+		ppu_write(p, ppu.fg, p->width / 2 - 0x10 / 2 + x, p->height / 2, 2);

+		ppu_write(p, ppu.fg, p->width / 2, p->height / 2 - 0x10 / 2 + x, 2);

 	}

 }

 static void

 redraw(Uxn *u)

 {

-	Uint16 x, y, y0 = 0, y1 = ppu.height;

-	SDL_Rect up = gRect;

+	Uint16 x, y;

 	if(devsystem->dat[0xe])

 		draw_inspect(&ppu, u->wst.dat, u->wst.ptr, u->rst.ptr, u->ram.dat);

-	if(!reqdraw && ppu.reqdraw) {

-		y0 = ppu.i0 / ppu.stride;

-		y1 = ppu.i1 / ppu.stride + 1;

-		up.y += y0;

-		up.h = y1 - y0;

-	}

-	for(y = y0; y < y1; ++y)

+	for(y = 0; y < ppu.height; ++y)

 		for(x = 0; x < ppu.width; ++x)

 			ppu_screen[x + y * ppu.width] = palette[ppu_read(&ppu, x, y)];

-	SDL_UpdateTexture(gTexture, &up, ppu_screen + y0 * ppu.width, ppu.width * sizeof(Uint32));

+	SDL_UpdateTexture(gTexture, &gRect, ppu_screen, ppu.width * sizeof(Uint32));

 	SDL_RenderClear(gRenderer);

 	SDL_RenderCopy(gRenderer, gTexture, NULL, NULL);

 	SDL_RenderPresent(gRenderer);

-	reqdraw = 0;

-	ppu_frame(&ppu);

+	ppu.reqdraw = 0;

 }

 static void

@@ -395,7 +390,7 @@ screen_talk(Device *d, Uint8 b0, Uint8 w)

 			Uint16 x = peek16(d->dat, 0x8);

 			Uint16 y = peek16(d->dat, 0xa);

 			Uint8 layer = d->dat[0xe] & 0x40;

-			ppu_write(&ppu, layer, x, y, d->dat[0xe] & 0x3);

+			ppu_write(&ppu, layer ? ppu.fg : ppu.bg, x, y, d->dat[0xe] & 0x3);

 			if(d->dat[0x6] & 0x01) poke16(d->dat, 0x8, x + 1); /* auto x+1 */

 			if(d->dat[0x6] & 0x02) poke16(d->dat, 0xa, y + 1); /* auto y+1 */

 			break;

@@ -406,14 +401,15 @@ screen_talk(Device *d, Uint8 b0, Uint8 w)

 			Uint8 layer = d->dat[0xf] & 0x40;

 			Uint8 *addr = &d->mem[peek16(d->dat, 0xc)];

 			if(d->dat[0xf] & 0x80) {

-				ppu_2bpp(&ppu, layer, x, y, addr, d->dat[0xf] & 0xf, d->dat[0xf] & 0x10, d->dat[0xf] & 0x20);

+				ppu_2bpp(&ppu, layer ? ppu.fg : ppu.bg, x, y, addr, d->dat[0xf] & 0xf, d->dat[0xf] & 0x10, d->dat[0xf] & 0x20);

 				if(d->dat[0x6] & 0x04) poke16(d->dat, 0xc, peek16(d->dat, 0xc) + 16); /* auto addr+16 */

 			} else {

-				ppu_1bpp(&ppu, layer, x, y, addr, d->dat[0xf] & 0xf, d->dat[0xf] & 0x10, d->dat[0xf] & 0x20);

+				ppu_1bpp(&ppu, layer ? ppu.fg : ppu.bg, x, y, addr, d->dat[0xf] & 0xf, d->dat[0xf] & 0x10, d->dat[0xf] & 0x20);

 				if(d->dat[0x6] & 0x04) poke16(d->dat, 0xc, peek16(d->dat, 0xc) + 8); /* auto addr+8 */

 			}

 			if(d->dat[0x6] & 0x01) poke16(d->dat, 0x8, x + 8); /* auto x+8 */

 			if(d->dat[0x6] & 0x02) poke16(d->dat, 0xa, y + 8); /* auto y+8 */

+			ppu.reqdraw = 1;

 			break;

 		}

 		}

@@ -546,7 +542,7 @@ run(Uxn *u)

 			}

 		}

 		uxn_eval(u, devscreen->vector);

-		if(reqdraw || ppu.reqdraw || devsystem->dat[0xe])

+		if(ppu.reqdraw || devsystem->dat[0xe])

 			redraw(u);

 		if(!BENCH) {

 			elapsed = (SDL_GetPerformanceCounter() - start) / (double)SDL_GetPerformanceFrequency() * 1000.0f;