Toggle monochromatic mode

src/devices/screen.c

@@ -24,6 +24,9 @@ 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 Uint32 palette_mono[] = {
+	0x0f000000, 0x0fffffff};
+
 static void
 screen_write(UxnScreen *p, Layer *layer, Uint16 x, Uint16 y, Uint8 color)
 {
@@ -103,8 +106,14 @@ screen_redraw(UxnScreen *p, Uint32 *pixels)
 	Uint32 i, size = p->width * p->height, palette[16];
 	for(i = 0; i < 16; i++)
 		palette[i] = p->palette[(i >> 2) ? (i >> 2) : (i & 3)];
-	for(i = 0; i < size; i++)
-		pixels[i] = palette[p->fg.pixels[i] << 2 | p->bg.pixels[i]];
+	if(p->mono) {
+		for(i = 0; i < size; i++)
+			pixels[i] = palette_mono[(p->fg.pixels[i] << 2 | p->bg.pixels[i]) & 0x1];
+	} else {
+		for(i = 0; i < size; i++)
+			pixels[i] = palette[p->fg.pixels[i] << 2 | p->bg.pixels[i]];
+	}
+
 	p->fg.changed = p->bg.changed = 0;
 }
 
@@ -114,6 +123,13 @@ clamp(int val, int min, int max)
 	return (val >= min) ? (val <= max) ? val : max : min;
 }
 
+void
+screen_mono(UxnScreen *p, Uint32 *pixels)
+{
+	p->mono = !p->mono;
+	screen_redraw(p, pixels);
+}
+
 /* IO */
 
 Uint8

src/devices/screen.h

@@ -20,6 +20,7 @@ typedef struct UxnScreen {
 	Uint32 palette[4], *pixels;
 	Uint16 width, height;
 	Layer fg, bg;
+	Uint8 mono;
 } UxnScreen;
 
 extern UxnScreen uxn_screen;
@@ -28,6 +29,7 @@ void screen_palette(UxnScreen *p, Uint8 *addr);
 void screen_resize(UxnScreen *p, Uint16 width, Uint16 height);
 void screen_clear(UxnScreen *p, Layer *layer);
 void screen_redraw(UxnScreen *p, Uint32 *pixels);
+void screen_mono(UxnScreen *p, Uint32 *pixels);
 
 Uint8 screen_dei(Device *d, Uint8 port);
 void screen_deo(Device *d, Uint8 port);

src/uxnemu.c

@@ -363,6 +363,10 @@ do_shortcut(Uxn *u, SDL_Event *event)
 		capture_screen();
 	else if(event->key.keysym.sym == SDLK_F4)
 		restart(u);
+	else if(event->key.keysym.sym == SDLK_F5) {
+		screen_mono(&uxn_screen, uxn_screen.pixels);
+		redraw();
+	}
 }
 
 static int