Initial commit

image/codecs/hlz.cpp

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+/* 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 "image/codecs/hlz.h"
+
+#include "common/stream.h"
+#include "common/textconsole.h"
+#include "graphics/surface.h"
+
+namespace Image {
+
+HLZDecoder::HLZDecoder(int width, int height) : Codec(),
+	_width(width), _height(height), _surface(nullptr) {
+}
+
+HLZDecoder::~HLZDecoder() {
+	if (_surface) {
+		_surface->free();
+		delete _surface;
+	}
+}
+
+const Graphics::Surface *HLZDecoder::decodeFrame(Common::SeekableReadStream &stream) {
+	if (!_surface) {
+		_surface = new Graphics::Surface();
+	}
+
+	_surface->create(_width, _height, Graphics::PixelFormat::createFormatCLUT8());
+
+	byte *dst = (byte *)_surface->getPixels();
+	decodeFrameInPlace(stream, uint32(-1), dst);
+
+	return _surface;
+}
+
+Graphics::PixelFormat HLZDecoder::getPixelFormat() const {
+	return Graphics::PixelFormat::createFormatCLUT8();
+}
+
+static inline uint getReg(Common::SeekableReadStream &stream, uint32 *size, uint32 *reg,
+						  int *regBits) {
+	if (*regBits == 0) {
+		if (*size < 4) {
+			error("Can't feed register: not enough data");
+		}
+		*reg = stream.readUint32LE();
+		*size -= 4;
+		*regBits = 32;
+	}
+	uint ret = (*reg >> 31) & 0x1;
+	*reg <<= 1;
+	(*regBits)--;
+	return ret;
+}
+
+void HLZDecoder::decodeFrameInPlace(Common::SeekableReadStream &stream, uint32 size, byte *dst) {
+	bool eof = false;
+	bool checkSize = (size != (uint32) - 1);
+	byte *orig = dst;
+	uint32 reg = 0;
+	int regBits = 0;
+#define GETREG() getReg(stream, &size, &reg, &regBits)
+
+	while (!eof) {
+		if (GETREG()) {
+			if (size < 1) {
+				error("Can't read pixel byte");
+			}
+			byte c = stream.readByte();
+			*(dst++) = c;
+			size--;
+		} else {
+			int offset, repeat_count;
+			if (GETREG()) {
+				// Long repeat
+				if (size < 2) {
+					error("Can't read repeat count/offset");
+				}
+				uint16 tmp = stream.readUint16LE();
+				size -= 2;
+				repeat_count = tmp & 0x7;
+				offset = (tmp >> 3) - 0x2000;
+				if (repeat_count == 0) {
+					if (size < 1) {
+						error("Can't read long repeat count");
+					}
+					repeat_count = stream.readByte();
+					size--;
+					if (repeat_count == 0) {
+						eof = true;
+						continue;
+					}
+				}
+			} else {
+				// Short repeat
+				repeat_count = GETREG() << 1;
+				repeat_count |= GETREG();
+				if (size < 1) {
+					error("Can't read offset byte");
+				}
+				offset = stream.readByte() - 0x100;
+				size--;
+			}
+			repeat_count += 2;
+			if (dst + offset < orig) {
+				error("Invalid offset %d, dst is %d", offset, (int)(dst - orig));
+			}
+			for (; repeat_count > 0; repeat_count--) {
+				// offset is always < 0
+				*dst = *(dst + offset);
+				dst++;
+			}
+		}
+	}
+	if (checkSize && size != 0) {
+		stream.skip(size);
+	}
+#undef GETREG
+}
+
+} // End of namespace Image