/* ScummVM - Graphic Adventure Engine
 *
 * ScummVM is the legal property of its developers, whose names
 * are too numerous to list here. Please refer to the COPYRIGHT
 * file distributed with this source distribution.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

#include "common/endian.h"
#include "common/config-manager.h"

#include "scumm/scumm.h"
#include "scumm/charset.h"
#include "scumm/util.h"
#include "scumm/resource.h"

#ifndef DISABLE_TOWNS_DUAL_LAYER_MODE

namespace Scumm {

void ScummEngine::towns_drawStripToScreen(VirtScreen *vs, int dstX, int dstY, int srcX, int srcY, int width, int height) {
	if (width <= 0 || height <= 0 || !_townsScreen)
		return;

	assert(_textSurface.getPixels());
	int m = (vs->number == kBannerVirtScreen) ? 1 : _textSurfaceMultiplier;

	const uint8 *src1 = vs->getPixels(srcX, srcY);
	const uint8 *src2 = (uint8 *)_textSurface.getBasePtr(srcX * m, (srcY + vs->topline - _screenTop) * m);
	int dstXScr = dstX + _scrollDestOffset;
	uint8 *dst1 = _townsScreen->getLayerPixels(0, dstXScr, dstY);
	uint16 *dst1a = (uint16*)dst1;
	uint8 *dst2 = _townsScreen->getLayerPixels(1, dstX * m, dstY * m);

	int lw1 = _townsScreen->getLayerWidth(0);
	int lp1 = _townsScreen->getLayerPitch(1);
	int dp2 = lp1 - width * m * _townsScreen->getLayerBpp(1);
	int sp1 = vs->pitch - (width * vs->format.bytesPerPixel);
	int sp2 = _textSurface.pitch - width * m;

	if (vs->number == kMainVirtScreen || ((_game.id == GID_INDY3 || _game.id == GID_ZAK) && vs->number != kBannerVirtScreen)) {
		if (_outputPixelFormat.bytesPerPixel == 2) {
			for (int h = 0; h < height; ++h) {
				uint16 *dst1tmp = dst1a;
				int xpos = dstXScr;
				for (int w = 0; w < width; ++w) {
					*dst1a++ = _16BitPalette[*src1++];
					if (++xpos == lw1) {
						dst1a -= lw1;
						xpos = 0;
					}
				}
				src1 += sp1;
				dst1a = dst1tmp + lw1;
			}
		} else {
			for (int h = 0; h < height; ++h) {
				uint8 *dst1tmp = dst1;
				int xpos = dstXScr;
				for (int w = 0; w < width; ++w) {
					*dst1++ = *src1++;
					if (++xpos == lw1) {
						dst1 -= lw1;
						xpos = 0;
					}
				}
				src1 += sp1;
				dst1 = dst1tmp + lw1;
			}
		}

		for (int h = 0; h < height * m; ++h) {
			memcpy(dst2, src2, width * m);
			src2 += _textSurface.pitch;
			dst2 += lp1;
		}

	} else {
		dst1 = dst2;
		uint8 t = 0;
		uint8 s2 = 0;
		uint8 s3 = 0;

		for (int h = 0; h < height; ++h) {
			if (m == 2) {
				uint16 *d = reinterpret_cast<uint16*>(dst1);
				for (int w = 0; w < width; ++w) {
					t = (*src1++) & 0x0f;
					*d++ = (t << 8) | t;
				}
			} else if (m == 1) {
				for (int w = 0; w < width; ++w) {
					t = (*src1++) & 0x0f;
					*dst1++ = t;
				}
			} else {
				error ("ScummEngine::towns_drawStripToScreen(): Unexpected text surface multiplier %d", m);
			}

			if (vs->number == kBannerVirtScreen) {
				dst2 += lp1;
				dst1 = dst2;
			} else {
				const uint8 *src3 = src2;
				dst1 = dst2;
				if (m == 2) {
					dst2 += lp1;
					src3 += lp1;
					for (int w = 0; w < (width << 1); ++w) {
						t = *dst1;
						s2 = *src2++ & 0x0f;
						s3 = *src3++ & 0x0f;
						*dst2++ = (s3 | (t & _townsLayer2Mask[s3]));
						*dst1++ = (s2 | (t & _townsLayer2Mask[s2]));
					}
				} else if (m == 1) {
					dst2 += width;
					src3 += width;
					for (int w = 0; w < width; ++w) {
						t = *dst1;
						s2 = *src2++ & 0x0f;
						*dst1++ = (s2 | (t & _townsLayer2Mask[s2]));
					}
				} else {
					error("ScummEngine::towns_drawStripToScreen(): Unexpected text surface multiplier %d", m);
				}
				src2 = src3 + sp2;
				dst1 = dst2 + dp2;
				dst2 += dp2;
			}
			src1 += sp1;
		}
	}

	_townsScreen->addDirtyRect(dstX * m, dstY * m, width * m, height * m);
}


void ScummEngine::towns_fillTopLayerRect(int x1, int y1, int x2, int y2, int col) {
	if (!_townsScreen)
		return;
	_townsScreen->fillRect(1, x1, y1, x2, y2, col);
}

void ScummEngine::towns_swapVirtScreenArea(VirtScreen *vs, int x, int y, int w, int h) {
	if (!_townsScreen)
		return;

	_townsScreen->swapAreaWithBuffer(1, x, y, w, h, vs->getPixels(0, 0));
}

void ScummEngine::towns_clearStrip(int strip) {
	if (!_townsScreen)
		return;

	int h = _screenHeight;
	int pitch = _townsScreen->getLayerPitch(0) >> 2;
	uint32 *dst1 = (uint32*)_townsScreen->getLayerPixels(0, (strip * 8 + _scrollDestOffset) % _townsScreen->getLayerWidth(0), 0);
	if (_game.version == 5) {
		dst1 += (90 * pitch);
		h = 56;
	}
	uint32 *dst2 = dst1 + 1;
	uint32 *dst3 = dst2 + 1;
	uint32 *dst4 = dst3 + 1;

	if (_townsScreen->getLayerBpp(0) == 2) {
		while (h--) {
			*dst1 = *dst2 = *dst3 = *dst4 = 0;
			dst1 += pitch;
			dst2 += pitch;
			dst3 += pitch;
			dst4 += pitch;
		}
	} else {
		while (h--) {
			*dst1 = *dst2 = 0;
			dst1 += pitch;
			dst2 += pitch;
		}
	}
}

void ScummEngine::requestScroll(int dir) {
	if (_enableSmoothScrolling && !_fastMode) {
		int lw = _townsScreen->getLayerWidth(0);
		// Wait for opposite direction scroll to finish.
		towns_waitForScroll(-dir);

		// WORKAROUND: In the LOOM intro the messenger nymph moves up the mountain so fast
		// (and thus accumulates so many scroll requests) that this will make the graphics
		// layer (width 512) wrap around. This causes a visible graphics glitch. The glitch
		// is exactly the same when starting the game in the UNZ emulator, so this is not
		// a mistake on my part. I work around this by adding an extra wait if the queued
		// up scroll requests exceed the critical mark. It is actually the exact same fix
		// that the SCUMM 5 games use for scrollEffect().
		towns_waitForScroll(dir, (lw - _screenWidth - 8) * dir);

		_scrollDestOffset = (_scrollDestOffset - 8 * dir) % lw;
		_scrollRequest += (8 * dir);
		towns_clearStrip(_scrollFeedStrips[dir + 1]);
	}
	redrawBGStrip(_scrollFeedStrips[dir + 1], 1);
}

void ScummEngine::towns_waitForScroll(int waitForDirection, int threshold) {
	while (!shouldQuit() && _townsScreen && (_scrollRequest || _townsScreen->isScrolling(0, waitForDirection, threshold)))
		waitForTimer(0);
}

void ScummEngine::towns_updateGfx() {
	if (!_townsScreen)
		return;

	// Determine whether the smooth scrolling is likely to fall behind and needs to catch up (becoming more sloppy than smooth). It depends
	// monstly on the hardware and the filter settings. Calls to _system->updateScreen() can be very expensive with the "wrong" filter setting.
	// We simply check whether the average screen update duration would fit into a 60 Hz tick. If catchup mode is triggered once, it stays on
	// permanently. Otherwise the scrolling can become very jerky when the engine keeps jumping between the settings (usually triggering it shortly
	// after the start of a scrolling, resulting in a very visible jerk, and then falling back to non-catchup after the scrolling is done).
	uint32 cur = _system->getMillis();
	if (!_refreshNeedCatchUp) {
		int dur = 0;
		for (int i = 0; i < ARRAYSIZE(_refreshDuration); ++i)
			dur += _refreshDuration[i];
		_refreshNeedCatchUp = (dur / ARRAYSIZE(_refreshDuration)) > (1000 / 60);
	}

	if (_enableSmoothScrolling) {
		int scrlTop = _virtscr[kMainVirtScreen].topline * _textSurfaceMultiplier;
		int scrlBottom = scrlTop + _virtscr[kMainVirtScreen].h * _textSurfaceMultiplier;

		while (_scrollTimer <= cur) {
			if (!_scrollTimer)
				_scrollTimer = cur;
			_scrollTimer += 1000 / 60;
			_townsScreen->scrollLayer(0, _scrollRequest, scrlTop, scrlBottom, VAR(VAR_TIMER_NEXT) == 0);
			if (_scrollNeedDeltaAdjust && _townsScreen->isScrolling(0, 0))
				_scrollDeltaAdjust++;
			_scrollRequest = 0;
			if (!_refreshNeedCatchUp)
				break;
		}
	}

	_townsScreen->update();
}

bool ScummEngine::towns_isRectInStringBox(int x1, int y1, int x2, int y2) {
	if (_game.platform == Common::kPlatformFMTowns && _charset->_hasMask && y1 <= _curStringRect.bottom && x1 <= _curStringRect.right && y2 >= _curStringRect.top && x2 >= _curStringRect.left)
		return true;
	return false;
}

void ScummEngine::towns_restoreCharsetBg() {
	if (_curStringRect.left != -1) {
		restoreBackground(_curStringRect, 0);
		_curStringRect.left = -1;
		_charset->_hasMask = false;
		_nextLeft = _string[0].xpos;
	}

	_nextLeft = _string[0].xpos;
	_nextTop = _string[0].ypos;
}

void ScummEngine::towns_scriptScrollEffect(int dir) {
	VirtScreen *vs = &_virtscr[kMainVirtScreen];
	const int stripWidth = 8;
	int destX = _gdi->_numStrips - 1;
	int srcX = 0;
	int layerW = _townsScreen->getLayerWidth(0);
	int threshold = (layerW - vs->w - stripWidth) * dir;
	if (dir == 1)
		SWAP(destX, srcX);

	// Wait for opposite direction scroll to finish.
	towns_waitForScroll(-dir);

	int scrlTop = _virtscr[kMainVirtScreen].topline * _textSurfaceMultiplier;
	int scrlBottom = scrlTop + _virtscr[kMainVirtScreen].h * _textSurfaceMultiplier;

	for (int x = 0; !shouldQuit() && x < _gdi->_numStrips; ++x) {
		_scrollDestOffset = (_scrollDestOffset - (dir << 3)) % layerW;
		uint32 nextFrame = _system->getMillis() + 1000 / 60;
		// Same as in requestScroll(): This prevents glitches from graphics layer wrapping.
		towns_waitForScroll(dir, threshold);
		_townsScreen->scrollLayer(0, dir << 3, scrlTop, scrlBottom, false);
		towns_drawStripToScreen(vs, destX << 3, vs->topline, (srcX + (-dir * x)) << 3, 0, stripWidth, vs->h);
		waitForTimer(nextFrame - _system->getMillis());
	}

	// Wait for all scrolls to finish.
	towns_waitForScroll(0);
}

#ifdef USE_RGB_COLOR
void ScummEngine::towns_setPaletteFromPtr(const byte *ptr, int numcolor) {
	setPaletteFromPtr(ptr, numcolor);

	if (_game.version == 5)
		towns_setTextPaletteFromPtr(_currentPalette);

	_townsOverrideShadowColor = 1;
	int m = 48;
	for (int i = 1; i < 16; ++i) {
		int val = _currentPalette[i * 3] + _currentPalette[i * 3 + 1] + _currentPalette[i * 3 + 2];
		if (m > val) {
			_townsOverrideShadowColor = i;
			m = val;
		}
	}
}

void ScummEngine::towns_setTextPaletteFromPtr(const byte *ptr) {
	memcpy(_textPalette, ptr, 48);
}
#endif

void ScummEngine::towns_setupPalCycleField(int x1, int y1, int x2, int y2) {
	if (_numCyclRects >= 10)
		return;
	_cyclRects[_numCyclRects].left = x1;
	_cyclRects[_numCyclRects].top = y1;
	_cyclRects[_numCyclRects].right = x2;
	_cyclRects[_numCyclRects].bottom = y2;
	_numCyclRects++;
	_townsPaletteFlags |= 1;
}

void ScummEngine::towns_processPalCycleField() {
	for (int i = 0; i < _numCyclRects; i++) {
		int x1 = _cyclRects[i].left - _virtscr[kMainVirtScreen].xstart;
		int x2 = _cyclRects[i].right - _virtscr[kMainVirtScreen].xstart;
		if (x1 < 0)
			x1 = 0;
		if (x2 > 320)
			x2 = 320;
		if (x2 > 0)
			markRectAsDirty(kMainVirtScreen, x1, x2, _cyclRects[i].top, _cyclRects[i].bottom);
	}
}

void ScummEngine::towns_resetPalCycleFields() {
	_numCyclRects = 0;
	_townsPaletteFlags &= ~1;
}

const uint8 ScummEngine::_townsLayer2Mask[] = {
	0xFF, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
};

TownsScreen::TownsScreen(OSystem *system) :	_system(system), _width(0), _height(0), _pixelFormat(system->getScreenFormat()), _numDirtyRects(0) {
	_width = _system->getWidth();
	_height = _system->getHeight();

	_semiSmoothScroll = ConfMan.getBool("semi_smooth_scroll");

	setupLayer(0, _width, _height, 1, 1, 256);
}

TownsScreen::~TownsScreen() {
	delete[] _layers[0].pixels;
	delete[] _layers[1].pixels;
	delete[] _layers[0].bltTmpPal;
	delete[] _layers[1].bltTmpPal;
	_dirtyRects.clear();
}

void TownsScreen::setupLayer(int layer, int width, int height, int scaleW, int scaleH, int numCol, void *pal) {
	if (layer & ~1)
		return;

	TownsScreenLayer *l = &_layers[layer];

	if (numCol >> 15)
		error("TownsScreen::setupLayer(): No more than 32767 colors supported.");

	if (width <= 0 || height <= 0 || numCol < 16)
		error("TownsScreen::setupLayer(): Invalid width/height/number of colors setting.");

	l->width = width;
	l->height = height;
	l->scaleW = scaleW;
	l->scaleH = scaleH;
	l->numCol = numCol;
	l->bpp = ((numCol - 1) & 0xff00) ? 2 : 1;
	l->pitch = width * l->bpp;
	l->palette = (uint8 *)pal;
	l->hScroll = 0;

	if (l->palette && _pixelFormat.bytesPerPixel == 1)
		warning("TownsScreen::setupLayer(): Layer palette usage requires 16 bit graphics setting.\nLayer palette will be ignored.");

	delete[] l->pixels;
	l->pixels = new uint8[l->pitch * l->height]();
	assert(l->pixels);

	delete[] l->bltTmpPal;
	l->bltTmpPal = (l->bpp == 1 && _pixelFormat.bytesPerPixel == 2) ? new uint16[l->numCol] : nullptr;

	l->enabled = true;
	_layers[0].onBottom = true;
	_layers[1].onBottom = !_layers[0].enabled;
	l->ready = true;
}

void TownsScreen::clearLayer(int layer) {
	if (layer & ~1)
		return;

	TownsScreenLayer *l = &_layers[layer];
	if (!l->ready)
		return;

	memset(l->pixels, 0, l->pitch * l->height);
	_dirtyRects.push_back(Common::Rect(_width - 1, _height - 1));
	_numDirtyRects = kFullRedraw;
}


void TownsScreen::fillRect(int layer, int x, int y, int w, int h, int col) {
	if ((layer & ~1) || w <= 0 || h <= 0)
		return;

	TownsScreenLayer *l = &_layers[layer];
	if (!l->ready)
		return;

	assert(x >= 0 && y >= 0 && ((x + w) * l->bpp) <= (l->pitch) && (y + h) <= (l->height));

	uint8 *pos = l->pixels + y * l->pitch + x * l->bpp;

	for (int i = 0; i < h; ++i) {
		if (l->bpp == 2) {
			for (int ii = 0; ii < w; ++ii) {
				*(uint16 *)pos = col;
				pos += 2;
			}
			pos += (l->pitch - w * 2);
		} else {
			memset(pos, col, w);
			pos += l->pitch;
		}
	}
	addDirtyRect(x * l->scaleW, y * l->scaleH, w * l->scaleW, h * l->scaleH);
}

void TownsScreen::swapAreaWithBuffer(int layer, int x, int y, int w, int h, byte *buffer) {
	if ((layer & ~1) || w <= 0 || h <= 0)
		return;

	TownsScreenLayer *l = &_layers[layer];
	if (!l->ready)
		return;

	assert(x >= 0 && y >= 0 && ((x + w) * l->bpp) <= (l->pitch) && (y + h) <= (l->height));

	uint8 *pos = l->pixels + y * l->pitch + x * l->bpp;

	for (int i = 0; i < h; ++i) {
		if (l->bpp == 2) {
			for (int ii = 0; ii < w; ++ii) {
				SWAP(*(uint16*)buffer, *(uint16*)pos);
				pos += 2;
				buffer += 2;
			}
			pos += (l->pitch - w * 2);
		} else {
			for (int ii = 0; ii < w; ++ii)
				SWAP(*buffer++, *pos++);
			pos += (l->pitch - w);
		}
	}
	addDirtyRect(x * l->scaleW, y * l->scaleH, w * l->scaleW, h * l->scaleH);
}

uint8 *TownsScreen::getLayerPixels(int layer, int x, int y) const {
	if (layer & ~1)
		return nullptr;

	const TownsScreenLayer *l = &_layers[layer];
	if (!l->ready)
		return nullptr;

	return l->pixels + y * l->pitch + (x % l->width) * l->bpp;
}

void TownsScreen::addDirtyRect(int x, int y, int w, int h) {
	if (w <= 0 || h <= 0 || _numDirtyRects > kDirtyRectsMax)
		return;

	if (_numDirtyRects == kDirtyRectsMax) {
		// full redraw
		_dirtyRects.clear();
		_dirtyRects.push_back(Common::Rect(_width - 1, _height - 1));
		_numDirtyRects++;
		return;
	}

	int x2 = x + w - 1;
	int y2 = y + h - 1;

	assert(x >= 0 && y >= 0 && x2 < _width && y2 < _height);

	bool merge = false;
	Common::List<Common::Rect>::iterator r2 = _dirtyRects.end();

	for (Common::List<Common::Rect>::iterator r = _dirtyRects.begin(); r != _dirtyRects.end(); ++r) {
		// Try to merge new rect with existing rects.
		if (merge) {
			r = _dirtyRects.begin();
			merge = false;
		}
		if (r == r2)
			continue;
		if (y == r->top && y2 == r->bottom) {
			if ((x >= r->left && x <= r->right) || (x2 >= r->left - 1 && x2 <= r->right)) {
				x = MIN<int>(x, r->left);
				x2 = MAX<int>(x2, r->right);
				merge = true;
			}
		}
		if (x == r->left && x2 == r->right) {
			if ((y >= r->top && y <= r->bottom) || (y2 >= r->top - 1 && y2 <= r->bottom)) {
				y = MIN<int>(y, r->top);
				y2 = MAX<int>(y2, r->bottom);
				merge = true;
			}
		}
		if (merge) {
			if (r2 == _dirtyRects.end())
				r2 = r;
			else
				r = _dirtyRects.erase(r);
		}
	}

	if (r2 == _dirtyRects.end()) {
		_dirtyRects.push_back(Common::Rect(x, y, x2, y2));
		_numDirtyRects++;
	} else {
		r2->left = x;
		r2->top = y;
		r2->right = x2;
		r2->bottom = y2;
	}
}

void TownsScreen::toggleLayers(int flags) {
	if (flags & ~3)
		return;

	_layers[0].enabled = (flags & 1) ? true : false;
	_layers[0].onBottom = true;
	_layers[1].enabled = (flags & 2) ? true : false;
	_layers[1].onBottom = !_layers[0].enabled;

	_dirtyRects.clear();
	_dirtyRects.push_back(Common::Rect(_width - 1, _height - 1));
	_numDirtyRects = kFullRedraw;

	_system->fillScreen(0);
	update();

	_system->updateScreen();
}

void TownsScreen::scrollLayer(int layer, int offset, int top, int bottom, bool fast) {
	if (layer & ~1)
		return;

	// This actually supports layer 0 only, since this is all we need.
	TownsScreenLayer *l = &_layers[layer];
	if (!l->ready)
		return;

	l->scrollRemainder += offset;
	if (!l->scrollRemainder)
		return;

	int step = (l->scrollRemainder > 0) ? -1 : 1;

	// Smooth scrolling isn't fast enough to keep up with the fast camera
	// movement in the Loom intro. Non-smooth scrolling is eight pixels at
	// at time, so two or four should be safe to use. Two is too slow, so
	// four it is.
	if (fast && _semiSmoothScroll)
		step *= 4;

	l->scrollRemainder += step;
	l->hScroll += step;
	l->hScroll %= l->width;

	if (top == 0 && bottom == _height - 1)
		_numDirtyRects = kDirtyRectsMax;

	addDirtyRect(0, top, _width, bottom - top);
}

void TownsScreen::update() {
#ifdef USE_RGB_COLOR
	update16BitPalette();
	updateScreenBuffer<uint16>();
#else
	updateScreenBuffer<uint8>();
#endif
}

#ifdef USE_RGB_COLOR
void TownsScreen::update16BitPalette() {
	for (int i = 0; i < 2; i++) {
		TownsScreenLayer *l = &_layers[i];
		if (!l->enabled || !l->ready)
			continue;

		if (_pixelFormat.bytesPerPixel == 2 && l->bpp == 1) {
			if (!l->palette)
				error("void TownsScreen::update16BitPalette(): No palette assigned to 8 bit layer %d", i);
			for (int ic = 0; ic < l->numCol; ic++)
				l->bltTmpPal[ic] = calc16BitColor(&l->palette[ic * 3]);
		}
	}
}

uint16 TownsScreen::calc16BitColor(const uint8 *palEntry) {
	return _pixelFormat.RGBToColor(palEntry[0], palEntry[1], palEntry[2]);
}
#endif

template<typename dstPixelType, typename srcPixelType, int scaleW, int scaleH, bool srcCol4bit> void TownsScreen::transferRect(uint8 *dst, int pitch, TownsScreenLayer *l, int x, int y, int w, int h) {
	uint8 *dst10 = dst + y * pitch * scaleH + x * sizeof(dstPixelType) * scaleW;
	uint8 *dst20 = (scaleH == 2) ? dst10 + pitch : nullptr;
	pitch *= scaleH;

	int x0 = (x + l->hScroll) % l->width;
	const uint8 *in0 = l->pixels + y * l->pitch + x0 * sizeof(srcPixelType);

	while (h-- >= 0) {
		const srcPixelType *in = (const srcPixelType*)in0;
		dstPixelType *dst10a = (dstPixelType*)dst10;
		dstPixelType *dst20a = (dstPixelType*)dst20;
		int x1 = x0;

		for (int w1 = w; w1 >= 0; w1--) {
			srcPixelType col = *in++;
			if (sizeof(dstPixelType) == 2) {
				if (sizeof(srcPixelType) == 1) {
					if (col || l->onBottom) {
						if (srcCol4bit)
							col = col & 0x0f;
						dstPixelType col2 = l->bltTmpPal[col];
						*dst10a = col2;
						if (scaleW == 2)
							*++dst10a = col2;
						if (scaleH == 2)
							*dst20a = col2;
						if (scaleW == 2 && scaleH == 2)
							*++dst20a = col2;
					}
					dst10a++;
					if (scaleH == 2)
						dst20a++;
				} else {
					*dst10a++ = col;
					if (scaleW == 2)
						*dst10a++ = col;
					if (scaleH == 2)
						*dst20a++ = col;
					if (scaleW == 2 && scaleH == 2)
						*dst20a++ = col;
				}
			} else {
				if (col || l->onBottom) {
					if (srcCol4bit)
						col = col & 0x0f;
					*dst10a = col;
					if (scaleW == 2)
						*++dst10a = col;
					if (scaleH == 2)
						*dst20a = col;
					if (scaleW == 2 && scaleH == 2)
						*++dst20a = col;
				}
				dst10a++;
				if (scaleH == 2)
					dst20a++;
			}
			if (++x1 == l->width) {
				in -= l->width;
				x1 -= l->width;
			}
		}
		in0 += l->pitch;
		dst10 += pitch;
		if (scaleH == 2)
			dst20 += pitch;
	}
}

#ifdef USE_RGB_COLOR
template void TownsScreen::transferRect<uint16, uint16, 1, 1, false>(uint8 *dst, int pitch, TownsScreenLayer *l, int x, int y, int w, int h);
template void TownsScreen::transferRect<uint16, uint16, 2, 2, false>(uint8 *dst, int pitch, TownsScreenLayer *l, int x, int y, int w, int h);
template void TownsScreen::transferRect<uint16, uint8, 1, 1, true>(uint8 *dst, int pitch, TownsScreenLayer *l, int x, int y, int w, int h);
#else
template void TownsScreen::transferRect<uint8, uint8, 2, 2, false>(uint8 *dst, int pitch, TownsScreenLayer *l, int x, int y, int w, int h);
template void TownsScreen::transferRect<uint8, uint8, 1, 1, false>(uint8 *dst, int pitch, TownsScreenLayer *l, int x, int y, int w, int h);
template void TownsScreen::transferRect<uint8, uint8, 1, 1, true>(uint8 *dst, int pitch, TownsScreenLayer *l, int x, int y, int w, int h);
#endif

template<typename dstPixelType> void TownsScreen::updateScreenBuffer() {
	Graphics::Surface *s = _system->lockScreen();
	if (!s)
		error("TownsScreen::updateOutputBuffer(): Failed to allocate screen buffer");
	uint8 *dst = (uint8*)s->getPixels();
	int pitch = s->pitch;

	for (int i = 0; i < 2; i++) {
		TownsScreenLayer *l = &_layers[i];
		if (!l->enabled || !l->ready)
			continue;
#ifdef USE_RGB_COLOR
		if (l->bpp == 2) {
			if (l->scaleH == 2 && l->scaleW == 2) {
				for (Common::List<Common::Rect>::iterator r = _dirtyRects.begin(); r != _dirtyRects.end(); ++r)
					transferRect<dstPixelType, uint16, 2, 2, false>(dst, pitch, l, r->left >> 1, r->top >> 1, (r->right - r->left) >> 1, (r->bottom - r->top) >> 1);
			} else if (l->scaleH == 1 && l->scaleW == 1) {
				for (Common::List<Common::Rect>::iterator r = _dirtyRects.begin(); r != _dirtyRects.end(); ++r)
					transferRect<dstPixelType, uint16, 1, 1, false>(dst, pitch, l, r->left, r->top, r->right - r->left, r->bottom - r->top);
			} else {
				error("TownsScreen::updateOutputBuffer(): Unsupported scale mode");
			}
		} else if (l->bpp == 1) {
#else
			if (l->numCol == 16) {
#endif
				if (l->scaleH == 1 && l->scaleW == 1) {
					for (Common::List<Common::Rect>::iterator r = _dirtyRects.begin(); r != _dirtyRects.end(); ++r)
						transferRect<dstPixelType, uint8, 1, 1, true>(dst, pitch, l, r->left, r->top, r->right - r->left, r->bottom - r->top);
				} else {
					error("TownsScreen::updateOutputBuffer(): Unsupported scale mode");
				}
#ifndef USE_RGB_COLOR
			} else {
				if (l->scaleH == 2 && l->scaleW == 2) {
					for (Common::List<Common::Rect>::iterator r = _dirtyRects.begin(); r != _dirtyRects.end(); ++r)
						transferRect<dstPixelType, uint8, 2, 2, false>(dst, pitch, l, r->left >> 1, r->top >> 1, (r->right - r->left) >> 1, (r->bottom - r->top) >> 1);
				} else if (l->scaleH == 1 && l->scaleW == 1) {
					for (Common::List<Common::Rect>::iterator r = _dirtyRects.begin(); r != _dirtyRects.end(); ++r)
						transferRect<dstPixelType, uint8, 1, 1, false>(dst, pitch, l, r->left, r->top, r->right - r->left, r->bottom - r->top);
				}
			}
#else
		} else {
			error("TownsScreen::updateOutputBuffer(): Unsupported pixel format");
		}
#endif
	}

	_system->unlockScreen();
	_dirtyRects.clear();
	_numDirtyRects = 0;
}

#ifdef USE_RGB_COLOR
template void TownsScreen::updateScreenBuffer<uint16>();
#else
template void TownsScreen::updateScreenBuffer<uint8>();
#endif

} // End of namespace Scumm

#endif // DISABLE_TOWNS_DUAL_LAYER_MODE