Avoid extra memcopy of pixels when blitting

For 32-bit displays Screen_blit is Blit_Copy_Raw, which is just a wrapper around memcopy from the_buffer to browser_pixels. However, since we just take the destination buffer and copy it to the shared array buffer, we can instead do that directly. We can now budget 1ms less in IdleWait for blitting, which reduces idle tab CPU use to ~30%
mihaip · Jun 7, 2021 · 973752a · 973752a
1 parent e357dc3
commit 973752a
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Showing 2 changed files with 25 additions and 18 deletions.
diff --git a/BasiliskII/src/SDL/video_sdl.cpp b/BasiliskII/src/SDL/video_sdl.cpp
@@ -667,6 +667,7 @@ class driver_base {
 
 	bool init_ok;	// Initialization succeeded (we can't use exceptions because of -fomit-frame-pointer)
 	SDL_Surface *s;	// The surface we draw into
+	bool is_raw_screen_blit;
 
 	// uint8 *browser_pixels;
 };
@@ -851,7 +852,7 @@ driver_window::driver_window(SDL_monitor_desc &m)
 		// assert(browser_pixels == NULL);
 		browser_pixels = alloc_browser_pixels(size_to_copy);
 		assert(browser_pixels);
-		printf("driver_window allocated browser_pixels=%p\n", (void *)browser_pixels); 
+		printf("driver_window allocated browser_pixels=%p\n", (void *)browser_pixels);
 		#ifdef EMSCRIPTEN
 		EM_ASM_({
 	  	Module.debugPointer($0);
@@ -903,7 +904,7 @@ driver_window::driver_window(SDL_monitor_desc &m)
 		#endif
 		D(bug("the_buffer = %p, the_buffer_copy = %p\n", the_buffer, the_buffer_copy));
 	}
-	
+
 #ifdef SHEEPSHAVER
 	// Create cursor
 	if ((sdl_cursor = SDL_CreateCursor(MacCursor + 4, MacCursor + 36, 16, 16, 0, 0)) != NULL) {
@@ -926,7 +927,7 @@ driver_window::driver_window(SDL_monitor_desc &m)
 	visualFormat.Rmask = f->Rmask;
 	visualFormat.Gmask = f->Gmask;
 	visualFormat.Bmask = f->Bmask;
-	Screen_blitter_init(visualFormat, true, mac_depth_of_video_depth(VIDEO_MODE_DEPTH));
+	is_raw_screen_blit = !Screen_blitter_init(visualFormat, true, mac_depth_of_video_depth(VIDEO_MODE_DEPTH));
 
 	// Load gray ramp to 8->16/32 expand map
 	if (!IsDirectMode(mode)) {
@@ -936,7 +937,7 @@ driver_window::driver_window(SDL_monitor_desc &m)
 					ExpandMap[i] = map_rgb(i, i, i, true);
 			#else
 					ExpandMap[i] = SDL_MapRGB(f, i, i, i);
-			#endif				
+			#endif
 		}
 	}
 	// Set frame buffer base
@@ -1055,7 +1056,7 @@ driver_fullscreen::driver_fullscreen(SDL_monitor_desc &m)
 		the_buffer = (uint8 *)vm_acquire_framebuffer(the_buffer_size);
 		D(bug("the_buffer = %p, the_buffer_copy = %p\n", the_buffer, the_buffer_copy));
 	}
-	
+
 	// Hide cursor
 	SDL_ShowCursor(0);
 
@@ -1066,7 +1067,7 @@ driver_fullscreen::driver_fullscreen(SDL_monitor_desc &m)
 	visualFormat.Rmask = f->Rmask;
 	visualFormat.Gmask = f->Gmask;
 	visualFormat.Bmask = f->Bmask;
-	Screen_blitter_init(visualFormat, true, mac_depth_of_video_depth(VIDEO_MODE_DEPTH));
+	is_raw_screen_blit = !Screen_blitter_init(visualFormat, true, mac_depth_of_video_depth(VIDEO_MODE_DEPTH));
 
 	// Load gray ramp to 8->16/32 expand map
 	if (!IsDirectMode(mode))
@@ -1914,7 +1915,7 @@ static int event2keycode(SDL_KeyboardEvent const &ev, bool key_down)
 #define SDL_N_EVENTS_PER_HANDLER 1
 
 static void handle_events(void)
-{ 
+{
 	#ifndef EMSCRIPTEN
 	SDL_Event events[SDL_N_EVENTS_PER_HANDLER];
 	const int n_max_events = sizeof(events) / sizeof(events[0]);
@@ -2417,7 +2418,7 @@ static void update_display_static(driver_base *drv)
 	#endif
 }
 
-static int emterpret_frame_count = 0; 
+static int emterpret_frame_count = 0;
 
 
 // Static display update (fixed frame rate, bounding boxes based)
@@ -2427,7 +2428,7 @@ static void update_display_static_bbox(driver_base *drv)
 
 	assert(Screen_blit);
 	const VIDEO_MODE &mode = drv->mode;
- 
+
 #ifdef EMSCRIPTEN_SAB
 	// Update the surface from Mac screen
 	const int bytes_per_row = VIDEO_MODE_ROW_BYTES;
@@ -2476,10 +2477,16 @@ static void update_display_static_bbox(driver_base *drv)
 		}, the_buffer, VIDEO_MODE_X, VIDEO_MODE_Y, 32);
 		assert(browser_pixels);
 #endif
-		Screen_blit((uint8 *)browser_pixels, the_buffer, size_to_copy);
+		uint8 *blit_buffer;
+		if (drv->is_raw_screen_blit) {
+			blit_buffer = the_buffer;
+		} else {
+			Screen_blit((uint8 *)browser_pixels, the_buffer, size_to_copy);
+			blit_buffer = browser_pixels;
+		}
 		EM_ASM_({
-	  	Module.blit($0, $1, $2, $3, $4);
-		}, browser_pixels, VIDEO_MODE_X, VIDEO_MODE_Y, 32, !IsDirectMode(mode));
+		Module.blit($0, $1, $2, $3, $4);
+		}, blit_buffer, VIDEO_MODE_X, VIDEO_MODE_Y, 32, !IsDirectMode(mode));
 	} else {
 		uint8 *pixels = (uint8 *)alloca(sizeof(uint8) * size_to_copy);
 		Screen_blit((uint8 *)pixels, the_buffer, size_to_copy);
@@ -2624,7 +2631,7 @@ static void video_refresh_dga_vosf(void)
 {
 	// Quit DGA mode if requested
 	possibly_quit_dga_mode();
-	
+
 	// Update display (VOSF variant)
 	static int tick_counter = 0;
 	if (++tick_counter >= frame_skip) {
@@ -2642,7 +2649,7 @@ static void video_refresh_window_vosf(void)
 {
 	// Ungrab mouse if requested
 	possibly_ungrab_mouse();
-	
+
 	// Update display (VOSF variant)
 	static int tick_counter = 0;
 	if (++tick_counter >= frame_skip) {
@@ -2702,11 +2709,11 @@ static void VideoRefreshInit(void)
 
 static inline void do_video_refresh(void)
 {
-	#ifdef EMSCRIPTEN 
+	#ifdef EMSCRIPTEN
 		#ifdef EMSCRIPTEN_MAINTHREAD
 			// TODO implement event handling for mainthread
 		#else
-			sdl_fake_read_input(); 
+			sdl_fake_read_input();
 		#endif
 	#else
 	// Handle SDL events

diff --git a/BasiliskII/src/Unix/BasiliskII-worker-boot.js b/BasiliskII/src/Unix/BasiliskII-worker-boot.js
@@ -320,9 +320,9 @@ function startEmulator(parentConfig) {
           inputBufferView,
           InputBufferAddresses.globalLockAddr,
           LockStates.READY_FOR_UI_THREAD,
-          // Time out such that we don't miss any frames (giving 3 milliseconds
+          // Time out such that we don't miss any frames (giving 2 milliseconds
           // for blit and any CPU emulation to run).
-          nextExpectedBlitTime - performance.now() - 3);
+          nextExpectedBlitTime - performance.now() - 2);
     },
 
     acquireInputLock: acquireInputLock,