GLK: ALAN2: Initial work on the Alan2 subengine

1 files changed, 70 insertions, 0 deletions

diff --git a/engines/glk/alan2/decode.h b/engines/glk/alan2/decode.h
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+++ b/engines/glk/alan2/decode.h
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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 2
+ * 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, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ */
+
+#ifndef GLK_ALAN2_DECODE
+#define GLK_ALAN2_DECODE
+
+#include "glk/alan2/alan2.h"
+#include "glk/alan2/acode.h"
+#include "common/file.h"
+
+namespace Glk {
+namespace Alan2 {
+
+// Structure for saved decode info
+typedef struct DecodeInfo {
+	long fpos;
+	int buffer;
+	int bits;
+	CodeValue value;
+	CodeValue high;
+	CodeValue low;
+} DecodeInfo;
+
+class Decode
+{
+public:
+	Decode(Common::File *txtFile, Aword *freq): _txtFile(txtFile), _freq(freq) {}
+	void startDecoding();
+	int decodeChar();
+	DecodeInfo *pushDecode();
+	void popDecode(DecodeInfo *info);
+	int inputBit();
+
+private:
+	// Bit output
+	int _decodeBuffer;	// Bits to be input
+	int _bitsToGo;		// Bits still in buffer
+	int _garbageBits;	// Bits past EOF
+
+	Aword *_freq;
+	Common::File *_txtFile;
+
+	// Current state of decoding
+	CodeValue _value;			// Currently seen code value
+	CodeValue _low, _high;		// Current code region
+};
+
+} // End of namespace Alan2
+} // Engine of namespace GLK
+
+#endif