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image/codecs/smc.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/>.
+ *
+ */
+
+// Based off ffmpeg's SMC decoder
+
+#include "image/codecs/smc.h"
+#include "common/stream.h"
+#include "common/textconsole.h"
+
+namespace Image {
+
+#define GET_BLOCK_COUNT() \
+  (opcode & 0x10) ? (1 + stream.readByte()) : 1 + (opcode & 0x0F);
+
+#define ADVANCE_BLOCK() \
+{ \
+	pixelPtr += 4; \
+	if (pixelPtr >= _surface->w) { \
+		pixelPtr = 0; \
+		rowPtr += _surface->w * 4; \
+	} \
+	totalBlocks--; \
+	if (totalBlocks < 0) { \
+		warning("block counter just went negative (this should not happen)"); \
+		return _surface; \
+	} \
+}
+
+SMCDecoder::SMCDecoder(uint16 width, uint16 height) {
+	_surface = new Graphics::Surface();
+	_surface->create(width, height, Graphics::PixelFormat::createFormatCLUT8());
+}
+
+SMCDecoder::~SMCDecoder() {
+	_surface->free();
+	delete _surface;
+}
+
+const Graphics::Surface *SMCDecoder::decodeFrame(Common::SeekableReadStream &stream) {
+	byte *pixels = (byte *)_surface->getPixels();
+
+	uint32 numBlocks = 0;
+	uint32 colorFlags = 0;
+	uint32 colorFlagsA = 0;
+	uint32 colorFlagsB = 0;
+
+	const uint16 rowInc = _surface->w - 4;
+	int32 rowPtr = 0;
+	int32 pixelPtr = 0;
+	uint32 blockPtr = 0;
+	uint32 prevBlockPtr = 0;
+	uint32 prevBlockPtr1 = 0, prevBlockPtr2 = 0;
+	byte prevBlockFlag = false;
+	uint32 pixel = 0;
+
+	uint32 colorPairIndex = 0;
+	uint32 colorQuadIndex = 0;
+	uint32 colorOctetIndex = 0;
+	uint32 colorTableIndex = 0;  // indices to color pair, quad, or octet tables
+
+	int32 chunkSize = stream.readUint32BE() & 0x00FFFFFF;
+	if (chunkSize != stream.size())
+		warning("MOV chunk size != SMC chunk size (%d != %d); ignoring SMC chunk size", chunkSize, (int)stream.size());
+
+	int32 totalBlocks = ((_surface->w + 3) / 4) * ((_surface->h + 3) / 4);
+
+	uint32 pixelSize = _surface->w * _surface->h;
+
+	// traverse through the blocks
+	while (totalBlocks != 0) {
+		// sanity checks
+
+		// make sure stream ptr hasn't gone out of bounds
+		if (stream.pos() > stream.size()) {
+			warning("SMC decoder just went out of bounds (stream ptr = %d, chunk size = %d)", (int)stream.pos(), (int)stream.size());
+			return _surface;
+		}
+
+		// make sure the row pointer hasn't gone wild
+		if (rowPtr >= _surface->w * _surface->h) {
+			warning("SMC decoder just went out of bounds (row ptr = %d, size = %d)", rowPtr, _surface->w * _surface->h);
+			return _surface;
+		}
+
+		byte opcode = stream.readByte();
+
+		switch (opcode & 0xF0) {
+		// skip n blocks
+		case 0x00:
+		case 0x10:
+			numBlocks = GET_BLOCK_COUNT();
+			while (numBlocks--) {
+				ADVANCE_BLOCK();
+			}
+			break;
+
+		// repeat last block n times
+		case 0x20:
+		case 0x30:
+			numBlocks = GET_BLOCK_COUNT();
+
+			// sanity check
+			if (rowPtr == 0 && pixelPtr == 0) {
+				warning("encountered repeat block opcode (%02X) but no blocks rendered yet", opcode & 0xF0);
+				break;
+			}
+
+			// figure out where the previous block started
+			if (pixelPtr == 0)
+				prevBlockPtr1 = (rowPtr - _surface->w * 4) + _surface->w - 4;
+			else
+				prevBlockPtr1 = rowPtr + pixelPtr - 4;
+
+			while (numBlocks--) {
+				blockPtr = rowPtr + pixelPtr;
+				prevBlockPtr = prevBlockPtr1;
+				for (byte y = 0; y < 4; y++) {
+					for (byte x = 0; x < 4; x++) {
+						if (blockPtr < pixelSize)
+							pixels[blockPtr] = pixels[prevBlockPtr];
+						blockPtr++, prevBlockPtr++;
+					}
+					blockPtr += rowInc;
+					prevBlockPtr += rowInc;
+				}
+				ADVANCE_BLOCK();
+			}
+			break;
+
+		// repeat previous pair of blocks n times
+		case 0x40:
+		case 0x50:
+			numBlocks = GET_BLOCK_COUNT();
+			numBlocks *= 2;
+
+			// sanity check
+			if (rowPtr == 0 && pixelPtr < 2 * 4) {
+				warning("encountered repeat block opcode (%02X) but not enough blocks rendered yet", opcode & 0xF0);
+				break;
+			}
+
+			// figure out where the previous 2 blocks started
+			if (pixelPtr == 0)
+				prevBlockPtr1 = (rowPtr - _surface->w * 4) + _surface->w - 4 * 2;
+			else if (pixelPtr == 4)
+				prevBlockPtr1 = (rowPtr - _surface->w * 4) + rowInc;
+			else
+				prevBlockPtr1 = rowPtr + pixelPtr - 4 * 2;
+
+			if (pixelPtr == 0)
+				prevBlockPtr2 = (rowPtr - _surface->w * 4) + rowInc;
+			else
+				prevBlockPtr2 = rowPtr + pixelPtr - 4;
+
+			prevBlockFlag = 0;
+			while (numBlocks--) {
+				blockPtr = rowPtr + pixelPtr;
+
+				if (prevBlockFlag)
+					prevBlockPtr = prevBlockPtr2;
+				else
+					prevBlockPtr = prevBlockPtr1;
+
+				prevBlockFlag = !prevBlockFlag;
+
+				for (byte y = 0; y < 4; y++) {
+					for (byte x = 0; x < 4; x++) {
+						if (blockPtr < pixelSize)
+							pixels[blockPtr] = pixels[prevBlockPtr];
+						blockPtr++, prevBlockPtr++;
+					}
+
+					blockPtr += rowInc;
+					prevBlockPtr += rowInc;
+				}
+				ADVANCE_BLOCK();
+			}
+			break;
+
+		// 1-color block encoding
+		case 0x60:
+		case 0x70:
+			numBlocks = GET_BLOCK_COUNT();
+			pixel = stream.readByte();
+
+			while (numBlocks--) {
+				blockPtr = rowPtr + pixelPtr;
+				for (byte y = 0; y < 4; y++) {
+					for (byte x = 0; x < 4; x++) {
+						if (blockPtr < pixelSize)
+							pixels[blockPtr] = pixel;
+						blockPtr++;
+					}
+
+					blockPtr += rowInc;
+				}
+				ADVANCE_BLOCK();
+			}
+			break;
+
+		// 2-color block encoding
+		case 0x80:
+		case 0x90:
+			numBlocks = (opcode & 0x0F) + 1;
+
+			// figure out which color pair to use to paint the 2-color block
+			if ((opcode & 0xF0) == 0x80) {
+				// fetch the next 2 colors from bytestream and store in next
+				// available entry in the color pair table
+				for (byte i = 0; i < CPAIR; i++) {
+					pixel = stream.readByte();
+					colorTableIndex = CPAIR * colorPairIndex + i;
+					_colorPairs[colorTableIndex] = pixel;
+				}
+
+				// this is the base index to use for this block
+				colorTableIndex = CPAIR * colorPairIndex;
+				colorPairIndex++;
+
+				// wraparound
+				if (colorPairIndex == COLORS_PER_TABLE)
+					colorPairIndex = 0;
+			} else
+				colorTableIndex = CPAIR * stream.readByte();
+
+			while (numBlocks--) {
+				colorFlags = stream.readUint16BE();
+				uint16 flagMask = 0x8000;
+				blockPtr = rowPtr + pixelPtr;
+				for (byte y = 0; y < 4; y++) {
+					for (byte x = 0; x < 4; x++) {
+						if (colorFlags & flagMask)
+							pixel = colorTableIndex + 1;
+						else
+							pixel = colorTableIndex;
+
+						flagMask >>= 1;
+
+						if (blockPtr < pixelSize)
+							pixels[blockPtr] = _colorPairs[pixel];
+
+						blockPtr++;
+					}
+
+					blockPtr += rowInc;
+				}
+				ADVANCE_BLOCK();
+			}
+			break;
+
+		// 4-color block encoding
+		case 0xA0:
+		case 0xB0:
+			numBlocks = (opcode & 0x0F) + 1;
+
+			// figure out which color quad to use to paint the 4-color block
+			if ((opcode & 0xF0) == 0xA0) {
+				// fetch the next 4 colors from bytestream and store in next
+				// available entry in the color quad table
+				for (byte i = 0; i < CQUAD; i++) {
+					pixel = stream.readByte();
+					colorTableIndex = CQUAD * colorQuadIndex + i;
+					_colorQuads[colorTableIndex] = pixel;
+				}
+
+				// this is the base index to use for this block
+				colorTableIndex = CQUAD * colorQuadIndex;
+				colorQuadIndex++;
+
+				// wraparound
+				if (colorQuadIndex == COLORS_PER_TABLE)
+					colorQuadIndex = 0;
+			} else
+				colorTableIndex = CQUAD * stream.readByte();
+
+			while (numBlocks--) {
+				colorFlags = stream.readUint32BE();
+
+				// flag mask actually acts as a bit shift count here
+				byte flagMask = 30;
+				blockPtr = rowPtr + pixelPtr;
+
+				for (byte y = 0; y < 4; y++) {
+					for (byte x = 0; x < 4; x++) {
+						pixel = colorTableIndex + ((colorFlags >> flagMask) & 0x03);
+						flagMask -= 2;
+
+						if (blockPtr < pixelSize)
+							pixels[blockPtr] = _colorQuads[pixel];
+						blockPtr++;
+					}
+					blockPtr += rowInc;
+				}
+				ADVANCE_BLOCK();
+			}
+			break;
+
+		// 8-color block encoding
+		case 0xC0:
+		case 0xD0:
+			numBlocks = (opcode & 0x0F) + 1;
+
+			// figure out which color octet to use to paint the 8-color block
+			if ((opcode & 0xF0) == 0xC0) {
+				// fetch the next 8 colors from bytestream and store in next
+				// available entry in the color octet table
+				for (byte i = 0; i < COCTET; i++) {
+					pixel = stream.readByte();
+					colorTableIndex = COCTET * colorOctetIndex + i;
+					_colorOctets[colorTableIndex] = pixel;
+				}
+
+				// this is the base index to use for this block
+				colorTableIndex = COCTET * colorOctetIndex;
+				colorOctetIndex++;
+
+				// wraparound
+				if (colorOctetIndex == COLORS_PER_TABLE)
+					colorOctetIndex = 0;
+			} else
+				colorTableIndex = COCTET * stream.readByte();
+
+			while (numBlocks--) {
+				/*
+				  For this input of 6 hex bytes:
+				    01 23 45 67 89 AB
+				  Mangle it to this output:
+				    flags_a = xx012456, flags_b = xx89A37B
+				*/
+
+				// build the color flags
+				byte flagData[6];
+				stream.read(flagData, 6);
+
+				colorFlagsA = ((READ_BE_UINT16(flagData) & 0xFFF0) << 8) | (READ_BE_UINT16(flagData + 2) >> 4);
+				colorFlagsB = ((READ_BE_UINT16(flagData + 4) & 0xFFF0) << 8) | ((flagData[1] & 0xF) << 8) |
+								((flagData[3] & 0xF) << 4) | (flagData[5] & 0xf);
+
+				colorFlags = colorFlagsA;
+
+				// flag mask actually acts as a bit shift count here
+				byte flagMask = 21;
+				blockPtr = rowPtr + pixelPtr;
+				for (byte y = 0; y < 4; y++) {
+					// reload flags at third row (iteration y == 2)
+					if (y == 2) {
+						colorFlags = colorFlagsB;
+						flagMask = 21;
+					}
+
+					for (byte x = 0; x < 4; x++) {
+						pixel = colorTableIndex + ((colorFlags >> flagMask) & 0x07);
+						flagMask -= 3;
+
+						if (blockPtr < pixelSize)
+							pixels[blockPtr] = _colorOctets[pixel];
+
+						blockPtr++;
+					}
+
+					blockPtr += rowInc;
+				}
+				ADVANCE_BLOCK();
+			}
+			break;
+
+		// 16-color block encoding (every pixel is a different color)
+		case 0xE0:
+			numBlocks = (opcode & 0x0F) + 1;
+
+			while (numBlocks--) {
+				blockPtr = rowPtr + pixelPtr;
+				for (byte y = 0; y < 4; y++) {
+					for (byte x = 0; x < 4; x++) {
+						byte b = stream.readByte();
+						if (blockPtr < pixelSize)
+							pixels[blockPtr] = b;
+						blockPtr++;
+					}
+
+					blockPtr += rowInc;
+				}
+				ADVANCE_BLOCK();
+			}
+			break;
+
+		case 0xF0:
+			warning("0xF0 opcode seen in SMC chunk (contact the developers)");
+			break;
+
+		default:
+			break;
+		}
+	}
+
+	return _surface;
+}
+
+} // End of namespace Image