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engines/agos/drivers/accolade/driverfile.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 "audio/mididrv.h"
+#include "common/error.h"
+#include "common/file.h"
+
+namespace AGOS {
+
+// this reads and gets Accolade driver data
+// we need it for channel mapping, instrument mapping and other things
+// this driver data chunk gets passed to the actual music driver (MT32 / AdLib)
+void MidiDriver_Accolade_readDriver(Common::String filename, MusicType requestedDriverType, byte *&driverData, uint16 &driverDataSize, bool &isMusicDrvFile) {
+	Common::File *driverStream = new Common::File();
+
+	isMusicDrvFile = false;
+
+	if (!driverStream->open(Common::Path(filename))) {
+		error("%s: unable to open file", filename.c_str());
+	}
+
+	if (filename == "INSTR.DAT") {
+		// INSTR.DAT: used by Elvira 1
+		uint32 streamSize = driverStream->size();
+		uint32 streamLeft = streamSize;
+		uint16 skipChunks = 0; // 1 for MT32, 0 for AdLib
+		uint16 chunkSize  = 0;
+
+		switch (requestedDriverType) {
+		case MT_ADLIB:
+			skipChunks = 0;
+			break;
+		case MT_MT32:
+			skipChunks = 1; // Skip one entry for MT32
+			break;
+		case MT_CT460:
+			skipChunks = 2; // CT-460 data is the third entry
+			break;
+		default:
+			assert(0);
+			break;
+		}
+
+		do {
+			if (streamLeft < 2)
+				error("%s: unexpected EOF", filename.c_str());
+
+			chunkSize = driverStream->readUint16LE();
+			streamLeft -= 2;
+
+			if (streamLeft < chunkSize)
+				error("%s: unexpected EOF", filename.c_str());
+
+			if (skipChunks) {
+				// Skip the chunk
+				driverStream->skip(chunkSize);
+				streamLeft -= chunkSize;
+
+				skipChunks--;
+			}
+		} while (skipChunks);
+
+		// Seek over the ASCII string until there is a NUL terminator
+		byte curByte = 0;
+
+		do {
+			if (chunkSize == 0)
+				error("%s: no actual instrument data found", filename.c_str());
+
+			curByte = driverStream->readByte();
+			chunkSize--;
+		} while (curByte);
+
+		driverDataSize = chunkSize;
+
+		// Read the requested instrument data entry
+		driverData = new byte[driverDataSize];
+		driverStream->read(driverData, driverDataSize);
+
+	} else if (filename == "MUSIC.DRV") {
+		// MUSIC.DRV / used by Elvira 2 / Waxworks / Simon 1 demo
+		uint32 streamSize = driverStream->size();
+		uint32 streamLeft = streamSize;
+		uint16 getChunk   = 0; // 4 for MT32, 2 for AdLib
+
+		switch (requestedDriverType) {
+		case MT_ADLIB:
+			getChunk = 2;
+			break;
+		case MT_MT32:
+			getChunk = 4;
+			break;
+		default:
+			assert(0);
+			break;
+		}
+
+		if (streamLeft < 2)
+			error("%s: unexpected EOF", filename.c_str());
+
+		uint16 chunkCount = driverStream->readUint16LE();
+		streamLeft -= 2;
+
+		if (getChunk >= chunkCount)
+			error("%s: required chunk not available", filename.c_str());
+
+		uint16 headerOffset = 2 + (28 * getChunk);
+		streamLeft -= (28 * getChunk);
+
+		if (streamLeft < 28)
+			error("%s: unexpected EOF", filename.c_str());
+
+		// Seek to required chunk
+		driverStream->seek(headerOffset);
+		driverStream->skip(20); // skip over name
+		streamLeft -= 20;
+
+		uint16 musicDrvSignature = driverStream->readUint16LE();
+		uint16 musicDrvType = driverStream->readUint16LE();
+		uint16 chunkOffset = driverStream->readUint16LE();
+		uint16 chunkSize   = driverStream->readUint16LE();
+
+		// Security checks
+		if (musicDrvSignature != 0xFEDC)
+			error("%s: chunk signature mismatch", filename.c_str());
+		if (musicDrvType != 1)
+			error("%s: not a music driver", filename.c_str());
+		if (chunkOffset >= streamSize)
+			error("%s: driver chunk points outside of file", filename.c_str());
+
+		streamLeft = streamSize - chunkOffset;
+		if (streamLeft < chunkSize)
+			error("%s: driver chunk is larger than file", filename.c_str());
+
+		driverDataSize = chunkSize;
+
+		// Read the requested instrument data entry
+		driverData = new byte[driverDataSize];
+
+		driverStream->seek(chunkOffset);
+		driverStream->read(driverData, driverDataSize);
+		isMusicDrvFile = true;
+	}
+
+	driverStream->close();
+	delete driverStream;
+}
+
+} // End of namespace AGOS