OSYSTEM: Get rid of kFeatureAutoComputeDirtyRects

svn-id: r49388

11 files changed, 44 insertions, 326 deletions

diff --git a/backends/platform/gp2x/gp2x-common.h b/backends/platform/gp2x/gp2x-common.h
index 8183a87300..b54e2d4d4f 100644
--- a/backends/platform/gp2x/gp2x-common.h
+++ b/backends/platform/gp2x/gp2x-common.h
@@ -192,10 +192,6 @@ protected:
 	Graphics::PixelFormat _overlayFormat;
 
 	enum {
-		DF_WANT_RECT_OPTIM			= 1 << 0
-	};
-
-	enum {
 		kTransactionNone = 0,
 		kTransactionActive = 1,
 		kTransactionRollback = 2
@@ -235,7 +231,6 @@ protected:
 	Graphics::Surface _framebuffer;
 
 	/** Current video mode flags (see DF_* constants) */
-	uint32 _modeFlags;
 	bool _modeChanged;
 	int _screenChangeCount;
 
@@ -252,9 +247,6 @@ protected:
 	// Dirty rect management
 	SDL_Rect _dirtyRectList[NUM_DIRTY_RECT];
 	int _numDirtyRects;
-	uint32 *_dirtyChecksums;
-	bool _cksumValid;
-	int _cksumNum;
 
 	// Keyboard mouse emulation.  Disabled by fingolfin 2004-12-18.
 	// I am keeping the rest of the code in for now, since the joystick
@@ -351,9 +343,6 @@ protected:
 	Common::TimerManager *_timer;
 
 protected:
-	void addDirtyRgnAuto(const byte *buf);
-	void makeChecksums(const byte *buf);
-
 	virtual void addDirtyRect(int x, int y, int w, int h, bool realCoordinates = false);
 
 	void drawMouse();
diff --git a/backends/platform/gp2x/gp2x.cpp b/backends/platform/gp2x/gp2x.cpp
index 8669671c4e..88d4f9d632 100644
--- a/backends/platform/gp2x/gp2x.cpp
+++ b/backends/platform/gp2x/gp2x.cpp
@@ -193,13 +193,11 @@ void OSystem_GP2X::initBackend() {
 	memset(&_videoMode, 0, sizeof(_videoMode));
 	memset(&_transactionDetails, 0, sizeof(_transactionDetails));
 
-	_cksumValid = false;
 	_videoMode.mode = GFX_NORMAL;
 	_videoMode.scaleFactor = 1;
 	_scalerProc = Normal1x;
 	_videoMode.aspectRatioCorrection = ConfMan.getBool("aspect_ratio");
 	_scalerType = 0;
-	_modeFlags = 0;
 	_adjustZoomOnMouse = false;
 	ConfMan.setBool("FM_low_quality", true);
 
@@ -246,7 +244,7 @@ OSystem_GP2X::OSystem_GP2X()
 	_hwscreen(0), _screen(0), _tmpscreen(0),
 	_overlayVisible(false),
 	_overlayscreen(0), _tmpscreen2(0),
-	_scalerProc(0), _modeChanged(false), _screenChangeCount(0), _dirtyChecksums(0),
+	_scalerProc(0), _modeChanged(false), _screenChangeCount(0),
 	_mouseVisible(false), _mouseNeedsRedraw(false), _mouseData(0), _mouseSurface(0),
 	_mouseOrigSurface(0), _cursorTargetScale(1), _cursorPaletteDisabled(true),
 	_joystick(0),
@@ -281,7 +279,6 @@ OSystem_GP2X::~OSystem_GP2X() {
 	SDL_RemoveTimer(_timerID);
 	closeMixer();
 
-	free(_dirtyChecksums);
 	free(_currentPalette);
 	free(_cursorPalette);
 	free(_mouseData);
@@ -380,7 +377,6 @@ bool OSystem_GP2X::hasFeature(Feature f) {
 	return
 		(f == kFeatureFullscreenMode) ||
 		(f == kFeatureAspectRatioCorrection) ||
-		(f == kFeatureAutoComputeDirtyRects) ||
 		(f == kFeatureCursorHasPalette);
 }
 
@@ -391,12 +387,6 @@ void OSystem_GP2X::setFeatureState(Feature f, bool enable) {
 	case kFeatureAspectRatioCorrection:
 		setAspectRatioCorrection(enable);
 		break;
-	case kFeatureAutoComputeDirtyRects:
-		if (enable)
-			_modeFlags |= DF_WANT_RECT_OPTIM;
-		else
-			_modeFlags &= ~DF_WANT_RECT_OPTIM;
-		break;
 	case kFeatureDisableKeyFiltering:
 		// TODO: Extend as more support for this is added to engines.
 		return;
@@ -413,8 +403,6 @@ bool OSystem_GP2X::getFeatureState(Feature f) {
 		return false;
 	case kFeatureAspectRatioCorrection:
 		return _videoMode.aspectRatioCorrection;
-	case kFeatureAutoComputeDirtyRects:
-		return _modeFlags & DF_WANT_RECT_OPTIM;
 	default:
 		return false;
 	}
@@ -431,7 +419,6 @@ void OSystem_GP2X::quit() {
 	SDL_RemoveTimer(_timerID);
 	closeMixer();
 
-	free(_dirtyChecksums);
 	free(_currentPalette);
 	free(_cursorPalette);
 	free(_mouseData);
diff --git a/backends/platform/gp2x/graphics.cpp b/backends/platform/gp2x/graphics.cpp
index 449e744e8b..4a3c668c52 100644
--- a/backends/platform/gp2x/graphics.cpp
+++ b/backends/platform/gp2x/graphics.cpp
@@ -270,12 +270,7 @@ void OSystem_GP2X::initSize(uint w, uint h, const Graphics::PixelFormat *format)
 	_videoMode.screenWidth = w;
 	_videoMode.screenHeight = h;
 
-	_cksumNum = (w * h / (8 * 8));
-
 	_transactionDetails.sizeChanged = true;
-
-	free(_dirtyChecksums);
-	_dirtyChecksums = (uint32 *)calloc(_cksumNum * 2, sizeof(uint32));
 }
 
 int OSystem_GP2X::effectiveScreenHeight() const {
@@ -724,40 +719,31 @@ void OSystem_GP2X::copyRectToScreen(const byte *src, int pitch, int x, int y, in
 	assert(h > 0 && y + h <= _videoMode.screenHeight);
 	assert(w > 0 && x + w <= _videoMode.screenWidth);
 
-	if (IS_ALIGNED(src, 4) && pitch == _videoMode.screenWidth && x == 0 && y == 0 &&
-			w == _videoMode.screenWidth && h == _videoMode.screenHeight && _modeFlags & DF_WANT_RECT_OPTIM) {
-		/* Special, optimized case for full screen updates.
-		 * It tries to determine what areas were actually changed,
-		 * and just updates those, on the actual display. */
-		addDirtyRgnAuto(src);
-	} else {
-		/* Clip the coordinates */
-		if (x < 0) {
-			w += x;
-			src -= x;
-			x = 0;
-		}
+	/* Clip the coordinates */
+	if (x < 0) {
+		w += x;
+		src -= x;
+		x = 0;
+	}
 
-		if (y < 0) {
-			h += y;
-			src -= y * pitch;
-			y = 0;
-		}
+	if (y < 0) {
+		h += y;
+		src -= y * pitch;
+		y = 0;
+	}
 
-		if (w > _videoMode.screenWidth - x) {
-			w = _videoMode.screenWidth - x;
-		}
+	if (w > _videoMode.screenWidth - x) {
+		w = _videoMode.screenWidth - x;
+	}
 
-		if (h > _videoMode.screenHeight - y) {
-			h = _videoMode.screenHeight - y;
-		}
+	if (h > _videoMode.screenHeight - y) {
+		h = _videoMode.screenHeight - y;
+	}
 
-		if (w <= 0 || h <= 0)
-			return;
+	if (w <= 0 || h <= 0)
+		return;
 
-		_cksumValid = false;
-		addDirtyRect(x, y, w, h);
-	}
+	addDirtyRect(x, y, w, h);
 
 	// Try to lock the screen surface
 	if (SDL_LockSurface(_screen) == -1)
@@ -885,88 +871,6 @@ void OSystem_GP2X::addDirtyRect(int x, int y, int w, int h, bool realCoordinates
 	}
 }
 
-void OSystem_GP2X::makeChecksums(const byte *buf) {
-	assert(buf);
-	uint32 *sums = _dirtyChecksums;
-	uint x,y;
-	const uint last_x = (uint)_videoMode.screenWidth / 8;
-	const uint last_y = (uint)_videoMode.screenHeight / 8;
-
-	const uint BASE = 65521; /* largest prime smaller than 65536 */
-
-	/* the 8x8 blocks in buf are enumerated starting in the top left corner and
-	 * reading each line at a time from left to right */
-	for (y = 0; y != last_y; y++, buf += _videoMode.screenWidth * (8 - 1))
-		for (x = 0; x != last_x; x++, buf += 8) {
-			// Adler32 checksum algorithm (from RFC1950, used by gzip and zlib).
-			// This computes the Adler32 checksum of a 8x8 pixel block. Note
-			// that we can do the modulo operation (which is the slowest part)
-			// of the algorithm) at the end, instead of doing each iteration,
-			// since we only have 64 iterations in total - and thus s1 and
-			// s2 can't overflow anyway.
-			uint32 s1 = 1;
-			uint32 s2 = 0;
-			const byte *ptr = buf;
-			for (int subY = 0; subY < 8; subY++) {
-				for (int subX = 0; subX < 8; subX++) {
-					s1 += ptr[subX];
-					s2 += s1;
-				}
-				ptr += _videoMode.screenWidth;
-			}
-
-			s1 %= BASE;
-			s2 %= BASE;
-
-			/* output the checksum for this block */
-			*sums++ =  (s2 << 16) + s1;
-	}
-}
-
-void OSystem_GP2X::addDirtyRgnAuto(const byte *buf) {
-	assert(buf);
-	assert(IS_ALIGNED(buf, 4));
-
-	/* generate a table of the checksums */
-	makeChecksums(buf);
-
-	if (!_cksumValid) {
-		_forceFull = true;
-		_cksumValid = true;
-	}
-
-	/* go through the checksum list, compare it with the previous checksums,
-		 and add all dirty rectangles to a list. try to combine small rectangles
-		 into bigger ones in a simple way */
-	if (!_forceFull) {
-		int x, y, w;
-		uint32 *ck = _dirtyChecksums;
-
-		for (y = 0; y != _videoMode.screenHeight / 8; y++) {
-			for (x = 0; x != _videoMode.screenWidth / 8; x++, ck++) {
-				if (ck[0] != ck[_cksumNum]) {
-					/* found a dirty 8x8 block, now go as far to the right as possible,
-						 and at the same time, unmark the dirty status by setting old to new. */
-					w=0;
-					do {
-						ck[w + _cksumNum] = ck[w];
-						w++;
-					} while (x + w != _videoMode.screenWidth / 8 && ck[w] != ck[w + _cksumNum]);
-
-					addDirtyRect(x * 8, y * 8, w * 8, 8);
-
-					if (_forceFull)
-						goto get_out;
-				}
-			}
-		}
-	} else {
-		get_out:;
-		/* Copy old checksums to new */
-		memcpy(_dirtyChecksums + _cksumNum, _dirtyChecksums, _cksumNum * sizeof(uint32));
-	}
-}
-
 int16 OSystem_GP2X::getHeight() {
 	return _videoMode.screenHeight;
 }
@@ -1175,7 +1079,6 @@ void OSystem_GP2X::copyRectToOverlay(const OverlayColor *buf, int pitch, int x,
 		return;
 
 	// Mark the modified region as dirty
-	_cksumValid = false;
 	addDirtyRect(x, y, w, h);
 
 	if (SDL_LockSurface(_overlayscreen) == -1)
diff --git a/backends/platform/gp2xwiz/gp2xwiz-graphics.cpp b/backends/platform/gp2xwiz/gp2xwiz-graphics.cpp
index 28c03db4b0..6abddd52f3 100644
--- a/backends/platform/gp2xwiz/gp2xwiz-graphics.cpp
+++ b/backends/platform/gp2xwiz/gp2xwiz-graphics.cpp
@@ -127,12 +127,7 @@ void OSystem_GP2XWIZ::initSize(uint w, uint h) {
 		toggleMouseGrab();
 	}
 
-	_cksumNum = (w * h / (8 * 8));
-
 	_transactionDetails.sizeChanged = true;
-
-	free(_dirtyChecksums);
-	_dirtyChecksums = (uint32 *)calloc(_cksumNum * 2, sizeof(uint32));
 }
 
 bool OSystem_GP2XWIZ::loadGFXMode() {
diff --git a/backends/platform/linuxmoto/linuxmoto-graphics.cpp b/backends/platform/linuxmoto/linuxmoto-graphics.cpp
index 482ed772c7..a39416ebc4 100644
--- a/backends/platform/linuxmoto/linuxmoto-graphics.cpp
+++ b/backends/platform/linuxmoto/linuxmoto-graphics.cpp
@@ -128,12 +128,7 @@ void OSystem_LINUXMOTO::initSize(uint w, uint h) {
 		toggleMouseGrab();
 	}
 
-	_cksumNum = (w * h / (8 * 8));
-
 	_transactionDetails.sizeChanged = true;
-
-	free(_dirtyChecksums);
-	_dirtyChecksums = (uint32 *)calloc(_cksumNum * 2, sizeof(uint32));
 }
 
 bool OSystem_LINUXMOTO::loadGFXMode() {
diff --git a/backends/platform/samsungtv/samsungtv.cpp b/backends/platform/samsungtv/samsungtv.cpp
index 4f0f3a1e3e..aa79b92558 100644
--- a/backends/platform/samsungtv/samsungtv.cpp
+++ b/backends/platform/samsungtv/samsungtv.cpp
@@ -30,7 +30,6 @@
 bool OSystem_SDL_SamsungTV::hasFeature(Feature f) {
 	return
 		(f == kFeatureAspectRatioCorrection) ||
-		(f == kFeatureAutoComputeDirtyRects) ||
 		(f == kFeatureCursorHasPalette);
 }
 
@@ -39,12 +38,6 @@ void OSystem_SDL_SamsungTV::setFeatureState(Feature f, bool enable) {
 	case kFeatureAspectRatioCorrection:
 		setAspectRatioCorrection(enable);
 		break;
-	case kFeatureAutoComputeDirtyRects:
-		if (enable)
-			_modeFlags |= DF_WANT_RECT_OPTIM;
-		else
-			_modeFlags &= ~DF_WANT_RECT_OPTIM;
-		break;
 	default:
 		break;
 	}
@@ -56,8 +49,6 @@ bool OSystem_SDL_SamsungTV::getFeatureState(Feature f) {
 	switch (f) {
 	case kFeatureAspectRatioCorrection:
 		return _videoMode.aspectRatioCorrection;
-	case kFeatureAutoComputeDirtyRects:
-		return _modeFlags & DF_WANT_RECT_OPTIM;
 	default:
 		return false;
 	}
diff --git a/backends/platform/sdl/graphics.cpp b/backends/platform/sdl/graphics.cpp
index e0bf7565fb..82670cfcb7 100644
--- a/backends/platform/sdl/graphics.cpp
+++ b/backends/platform/sdl/graphics.cpp
@@ -469,12 +469,7 @@ void OSystem_SDL::initSize(uint w, uint h, const Graphics::PixelFormat *format)
 	_videoMode.screenWidth = w;
 	_videoMode.screenHeight = h;
 
-	_cksumNum = (w * h / (8 * 8));
-
 	_transactionDetails.sizeChanged = true;
-
-	free(_dirtyChecksums);
-	_dirtyChecksums = (uint32 *)calloc(_cksumNum * 2, sizeof(uint32));
 }
 
 int OSystem_SDL::effectiveScreenHeight() const {
@@ -976,16 +971,7 @@ void OSystem_SDL::copyRectToScreen(const byte *src, int pitch, int x, int y, int
 	assert(h > 0 && y + h <= _videoMode.screenHeight);
 	assert(w > 0 && x + w <= _videoMode.screenWidth);
 
-	if (IS_ALIGNED(src, 4) && pitch == _videoMode.screenWidth && x == 0 && y == 0 &&
-			w == _videoMode.screenWidth && h == _videoMode.screenHeight && _modeFlags & DF_WANT_RECT_OPTIM) {
-		/* Special, optimized case for full screen updates.
-		 * It tries to determine what areas were actually changed,
-		 * and just updates those, on the actual display. */
-		addDirtyRgnAuto(src);
-	} else {
-		_cksumValid = false;
-		addDirtyRect(x, y, w, h);
-	}
+	addDirtyRect(x, y, w, h);
 
 	// Try to lock the screen surface
 	if (SDL_LockSurface(_screen) == -1)
@@ -1131,89 +1117,6 @@ void OSystem_SDL::addDirtyRect(int x, int y, int w, int h, bool realCoordinates)
 	}
 }
 
-
-void OSystem_SDL::makeChecksums(const byte *buf) {
-	assert(buf);
-	uint32 *sums = _dirtyChecksums;
-	uint x,y;
-	const uint last_x = (uint)_videoMode.screenWidth / 8;
-	const uint last_y = (uint)_videoMode.screenHeight / 8;
-
-	const uint BASE = 65521; /* largest prime smaller than 65536 */
-
-	/* the 8x8 blocks in buf are enumerated starting in the top left corner and
-	 * reading each line at a time from left to right */
-	for (y = 0; y != last_y; y++, buf += _videoMode.screenWidth * (8 - 1))
-		for (x = 0; x != last_x; x++, buf += 8) {
-			// Adler32 checksum algorithm (from RFC1950, used by gzip and zlib).
-			// This computes the Adler32 checksum of a 8x8 pixel block. Note
-			// that we can do the modulo operation (which is the slowest part)
-			// of the algorithm) at the end, instead of doing each iteration,
-			// since we only have 64 iterations in total - and thus s1 and
-			// s2 can't overflow anyway.
-			uint32 s1 = 1;
-			uint32 s2 = 0;
-			const byte *ptr = buf;
-			for (int subY = 0; subY < 8; subY++) {
-				for (int subX = 0; subX < 8; subX++) {
-					s1 += ptr[subX];
-					s2 += s1;
-				}
-				ptr += _videoMode.screenWidth;
-			}
-
-			s1 %= BASE;
-			s2 %= BASE;
-
-			/* output the checksum for this block */
-			*sums++ =  (s2 << 16) + s1;
-	}
-}
-
-void OSystem_SDL::addDirtyRgnAuto(const byte *buf) {
-	assert(buf);
-	assert(IS_ALIGNED(buf, 4));
-
-	/* generate a table of the checksums */
-	makeChecksums(buf);
-
-	if (!_cksumValid) {
-		_forceFull = true;
-		_cksumValid = true;
-	}
-
-	/* go through the checksum list, compare it with the previous checksums,
-		 and add all dirty rectangles to a list. try to combine small rectangles
-		 into bigger ones in a simple way */
-	if (!_forceFull) {
-		int x, y, w;
-		uint32 *ck = _dirtyChecksums;
-
-		for (y = 0; y != _videoMode.screenHeight / 8; y++) {
-			for (x = 0; x != _videoMode.screenWidth / 8; x++, ck++) {
-				if (ck[0] != ck[_cksumNum]) {
-					/* found a dirty 8x8 block, now go as far to the right as possible,
-						 and at the same time, unmark the dirty status by setting old to new. */
-					w=0;
-					do {
-						ck[w + _cksumNum] = ck[w];
-						w++;
-					} while (x + w != _videoMode.screenWidth / 8 && ck[w] != ck[w + _cksumNum]);
-
-					addDirtyRect(x * 8, y * 8, w * 8, 8);
-
-					if (_forceFull)
-						goto get_out;
-				}
-			}
-		}
-	} else {
-		get_out:;
-		/* Copy old checksums to new */
-		memcpy(_dirtyChecksums + _cksumNum, _dirtyChecksums, _cksumNum * sizeof(uint32));
-	}
-}
-
 int16 OSystem_SDL::getHeight() {
 	return _videoMode.screenHeight;
 }
@@ -1432,7 +1335,6 @@ void OSystem_SDL::copyRectToOverlay(const OverlayColor *buf, int pitch, int x, i
 		return;
 
 	// Mark the modified region as dirty
-	_cksumValid = false;
 	addDirtyRect(x, y, w, h);
 
 	if (SDL_LockSurface(_overlayscreen) == -1)
diff --git a/backends/platform/sdl/sdl.cpp b/backends/platform/sdl/sdl.cpp
index c947e32cd8..f8ae824acf 100644
--- a/backends/platform/sdl/sdl.cpp
+++ b/backends/platform/sdl/sdl.cpp
@@ -149,7 +149,6 @@ void OSystem_SDL::initBackend() {
 	memset(&_videoMode, 0, sizeof(_videoMode));
 	memset(&_transactionDetails, 0, sizeof(_transactionDetails));
 
-	_cksumValid = false;
 #if !defined(_WIN32_WCE) && !defined(__SYMBIAN32__) && defined(USE_SCALERS)
 	_videoMode.mode = GFX_DOUBLESIZE;
 	_videoMode.scaleFactor = 2;
@@ -163,7 +162,6 @@ void OSystem_SDL::initBackend() {
 	_scalerProc = Normal1x;
 #endif
 	_scalerType = 0;
-	_modeFlags = 0;
 
 #if !defined(_WIN32_WCE) && !defined(__SYMBIAN32__)
 	_videoMode.fullscreen = ConfMan.getBool("fullscreen");
@@ -233,7 +231,7 @@ OSystem_SDL::OSystem_SDL()
 #endif
 	_overlayVisible(false),
 	_overlayscreen(0), _tmpscreen2(0),
-	_cdrom(0), _scalerProc(0), _modeChanged(false), _screenChangeCount(0), _dirtyChecksums(0),
+	_cdrom(0), _scalerProc(0), _modeChanged(false), _screenChangeCount(0),
 	_scrollLock(false),
 	_mouseVisible(false), _mouseNeedsRedraw(false), _mouseData(0), _mouseSurface(0),
 	_mouseOrigSurface(0), _cursorTargetScale(1), _cursorPaletteDisabled(true),
@@ -281,7 +279,6 @@ OSystem_SDL::~OSystem_SDL() {
 	SDL_RemoveTimer(_timerID);
 	closeMixer();
 
-	free(_dirtyChecksums);
 	free(_mouseData);
 
 	delete _savefile;
@@ -451,7 +448,6 @@ bool OSystem_SDL::hasFeature(Feature f) {
 	return
 		(f == kFeatureFullscreenMode) ||
 		(f == kFeatureAspectRatioCorrection) ||
-		(f == kFeatureAutoComputeDirtyRects) ||
 		(f == kFeatureCursorHasPalette) ||
 		(f == kFeatureIconifyWindow);
 }
@@ -464,12 +460,6 @@ void OSystem_SDL::setFeatureState(Feature f, bool enable) {
 	case kFeatureAspectRatioCorrection:
 		setAspectRatioCorrection(enable);
 		break;
-	case kFeatureAutoComputeDirtyRects:
-		if (enable)
-			_modeFlags |= DF_WANT_RECT_OPTIM;
-		else
-			_modeFlags &= ~DF_WANT_RECT_OPTIM;
-		break;
 	case kFeatureIconifyWindow:
 		if (enable)
 			SDL_WM_IconifyWindow();
@@ -487,8 +477,6 @@ bool OSystem_SDL::getFeatureState(Feature f) {
 		return _videoMode.fullscreen;
 	case kFeatureAspectRatioCorrection:
 		return _videoMode.aspectRatioCorrection;
-	case kFeatureAutoComputeDirtyRects:
-		return _modeFlags & DF_WANT_RECT_OPTIM;
 	default:
 		return false;
 	}
@@ -510,7 +498,6 @@ void OSystem_SDL::deinit() {
 	SDL_RemoveTimer(_timerID);
 	closeMixer();
 
-	free(_dirtyChecksums);
 	free(_mouseData);
 
 	delete _timer;
diff --git a/backends/platform/sdl/sdl.h b/backends/platform/sdl/sdl.h
index bfaabab80a..341a59c8cf 100644
--- a/backends/platform/sdl/sdl.h
+++ b/backends/platform/sdl/sdl.h
@@ -291,10 +291,6 @@ protected:
 	uint32 _cdEndTime, _cdStopTime;
 
 	enum {
-		DF_WANT_RECT_OPTIM			= 1 << 0
-	};
-
-	enum {
 		kTransactionNone = 0,
 		kTransactionActive = 1,
 		kTransactionRollback = 2
@@ -342,7 +338,6 @@ protected:
 	Graphics::Surface _framebuffer;
 
 	/** Current video mode flags (see DF_* constants) */
-	uint32 _modeFlags;
 	bool _modeChanged;
 	int _screenChangeCount;
 
@@ -354,9 +349,6 @@ protected:
 	// Dirty rect management
 	SDL_Rect _dirtyRectList[NUM_DIRTY_RECT];
 	int _numDirtyRects;
-	uint32 *_dirtyChecksums;
-	bool _cksumValid;
-	int _cksumNum;
 
 	// Keyboard mouse emulation.  Disabled by fingolfin 2004-12-18.
 	// I am keeping the rest of the code in for now, since the joystick
@@ -459,9 +451,6 @@ protected:
 	Common::TimerManager *_timer;
 
 protected:
-	void addDirtyRgnAuto(const byte *buf);
-	void makeChecksums(const byte *buf);
-
 	virtual void addDirtyRect(int x, int y, int w, int h, bool realCoordinates = false); // overloaded by CE backend
 
 	virtual void drawMouse(); // overloaded by CE backend
diff --git a/backends/platform/symbian/src/SymbianOS.cpp b/backends/platform/symbian/src/SymbianOS.cpp
index f8df2a5d5c..2ae47b07a8 100644
--- a/backends/platform/symbian/src/SymbianOS.cpp
+++ b/backends/platform/symbian/src/SymbianOS.cpp
@@ -83,7 +83,6 @@ bool OSystem_SDL_Symbian::hasFeature(Feature f) {
 	switch (f) {
 	case kFeatureFullscreenMode:
 	case kFeatureAspectRatioCorrection:
-	case kFeatureAutoComputeDirtyRects:
 	case kFeatureCursorHasPalette:
 #ifdef  USE_VIBRA_SE_PXXX
 	case kFeatureVibration:
diff --git a/backends/platform/wince/wince-sdl.cpp b/backends/platform/wince/wince-sdl.cpp
index 7ce689fb63..b3480702b5 100644
--- a/backends/platform/wince/wince-sdl.cpp
+++ b/backends/platform/wince/wince-sdl.cpp
@@ -926,7 +926,7 @@ const OSystem::GraphicsMode *OSystem_WINCE3::getSupportedGraphicsModes() const {
 }
 
 bool OSystem_WINCE3::hasFeature(Feature f) {
-	return (f == kFeatureAutoComputeDirtyRects || f == kFeatureVirtualKeyboard);
+	return (f == kFeatureVirtualKeyboard);
 }
 
 void OSystem_WINCE3::setFeatureState(Feature f, bool enable) {
@@ -1151,14 +1151,12 @@ bool OSystem_WINCE3::update_scalers() {
 				_scaleFactorYm = 1;
 				_scaleFactorYd = 1;
 				_scalerProc = DownscaleHorizByThreeQuarters;
-				_modeFlags = 0;
 			} else {
 				_scaleFactorXm = 1;
 				_scaleFactorXd = 1;
 				_scaleFactorYm = 1;
 				_scaleFactorYd = 1;
 				_scalerProc = Normal1x;
-				_modeFlags = 0;
 			}
 		} else if ( _orientationLandscape && (_videoMode.screenWidth == 320 || !_videoMode.screenWidth)) {
 			if (!_panelVisible && !_hasSmartphoneResolution  && !_overlayVisible && _canBeAspectScaled) {
@@ -1167,7 +1165,6 @@ bool OSystem_WINCE3::update_scalers() {
 				_scaleFactorYm = 6;
 				_scaleFactorYd = 5;
 				_scalerProc = Normal1xAspect;
-				_modeFlags = 0;
 				_videoMode.aspectRatioCorrection = true;
 			} else {
 				_scaleFactorXm = 1;
@@ -1175,7 +1172,6 @@ bool OSystem_WINCE3::update_scalers() {
 				_scaleFactorYm = 1;
 				_scaleFactorYd = 1;
 				_scalerProc = Normal1x;
-				_modeFlags = 0;
 			}
 		} else if (_videoMode.screenWidth == 640 && !(isOzone() && (getScreenWidth() >= 640 || getScreenHeight() >= 640))) {
 			_scaleFactorXm = 1;
@@ -1183,14 +1179,12 @@ bool OSystem_WINCE3::update_scalers() {
 			_scaleFactorYm = 1;
 			_scaleFactorYd = 2;
 			_scalerProc = DownscaleAllByHalf;
-			_modeFlags = 0;
 		} else if (_videoMode.screenWidth == 640 && (isOzone() && (getScreenWidth() >= 640 || getScreenHeight() >= 640))) {
 			_scaleFactorXm = 1;
 			_scaleFactorXd = 1;
 			_scaleFactorYm = 1;
 			_scaleFactorYd = 1;
 			_scalerProc = Normal1x;
-			_modeFlags = 0;
 		}
 
 		return true;
@@ -1203,7 +1197,6 @@ bool OSystem_WINCE3::update_scalers() {
 				_scaleFactorYm = 12;
 				_scaleFactorYd = 5;
 				_scalerProc = Normal2xAspect;
-				_modeFlags = 0;
 				_videoMode.aspectRatioCorrection = true;
 			} else if ( (_panelVisible || _overlayVisible) && _canBeAspectScaled ) {
 				_scaleFactorXm = 2;
@@ -1211,7 +1204,6 @@ bool OSystem_WINCE3::update_scalers() {
 				_scaleFactorYm = 2;
 				_scaleFactorYd = 1;
 				_scalerProc = Normal2x;
-				_modeFlags = 0;
 			}
 			return true;
 		}
@@ -1232,7 +1224,6 @@ bool OSystem_WINCE3::update_scalers() {
 		_scaleFactorYm = 7;
 		_scaleFactorYd = 8;
 		_scalerProc = SmartphoneLandscape;
-		_modeFlags = 0;
 		initZones();
 		return true;
 	}
@@ -1824,7 +1815,6 @@ void OSystem_WINCE3::copyRectToOverlay(const OverlayColor *buf, int pitch, int x
 		return;
 
 	// Mark the modified region as dirty
-	_cksumValid = false;
 	addDirtyRect(x, y, w, h);
 
 	undrawMouse();
@@ -1851,40 +1841,31 @@ void OSystem_WINCE3::copyRectToScreen(const byte *src, int pitch, int x, int y,
 
 	Common::StackLock lock(_graphicsMutex);	// Lock the mutex until this function ends
 
-	if (((long)src & 3) == 0 && pitch == _videoMode.screenWidth && x == 0 && y == 0 &&
-			w == _videoMode.screenWidth && h == _videoMode.screenHeight && _modeFlags & DF_WANT_RECT_OPTIM) {
-		/* Special, optimized case for full screen updates.
-		 * It tries to determine what areas were actually changed,
-		 * and just updates those, on the actual display. */
-		addDirtyRgnAuto(src);
-	} else {
-		/* Clip the coordinates */
-		if (x < 0) {
-			w += x;
-			src -= x;
-			x = 0;
-		}
+	/* Clip the coordinates */
+	if (x < 0) {
+		w += x;
+		src -= x;
+		x = 0;
+	}
 
-		if (y < 0) {
-			h += y;
-			src -= y * pitch;
-			y = 0;
-		}
+	if (y < 0) {
+		h += y;
+		src -= y * pitch;
+		y = 0;
+	}
 
-		if (w > _videoMode.screenWidth - x) {
-			w = _videoMode.screenWidth - x;
-		}
+	if (w > _videoMode.screenWidth - x) {
+		w = _videoMode.screenWidth - x;
+	}
 
-		if (h > _videoMode.screenHeight - y) {
-			h = _videoMode.screenHeight - y;
-		}
+	if (h > _videoMode.screenHeight - y) {
+		h = _videoMode.screenHeight - y;
+	}
 
-		if (w <= 0 || h <= 0)
-			return;
+	if (w <= 0 || h <= 0)
+		return;
 
-		_cksumValid = false;
-		addDirtyRect(x, y, w, h);
-	}
+	addDirtyRect(x, y, w, h);
 
 	undrawMouse();