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Diffstat (limited to 'common/bitstream.h')
-rw-r--r-- | common/bitstream.h | 107 |
1 files changed, 107 insertions, 0 deletions
diff --git a/common/bitstream.h b/common/bitstream.h new file mode 100644 index 0000000000..d9610b269a --- /dev/null +++ b/common/bitstream.h @@ -0,0 +1,107 @@ +/* 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. + * + */ + +// Based on eos' BitStream implementation + +#ifndef COMMON_BITSTREAM_H +#define COMMON_BITSTREAM_H + +#include "common/scummsys.h" + +namespace Common { + +class SeekableReadStream; + +/** + * A bit stream. + * + * Used in engines: + * - scumm + */ +class BitStream { +public: + BitStream(); + virtual ~BitStream(); + + /** Read a bit. */ + virtual uint32 getBit() = 0; + + /** Read a number of bits. */ + virtual uint32 getBits(uint32 n) = 0; + + /** Adding another bit. */ + virtual void addBit(uint32 &x, uint32 n) = 0; + + /** Skip a number of bits. */ + void skip(uint32 n); + + /** Get the current position. */ + virtual uint32 pos() const = 0; + /** Return the number of bits in the stream. */ + virtual uint32 size() const = 0; +}; + +/** A big endian bit stream. */ +class BitStreamBE : public BitStream { +public: + BitStreamBE(SeekableReadStream &stream, uint32 bitCount); + BitStreamBE(const byte *data, uint32 bitCount); + ~BitStreamBE(); + + uint32 getBit(); + uint32 getBits(uint32 n); + void addBit(uint32 &x, uint32 n); + + uint32 pos() const; + uint32 size() const; + +private: + SeekableReadStream *_stream; + + byte _value; ///< Current byte. + uint8 _inValue; ///< Position within the current byte. +}; + +/** A 32bit little endian bit stream. */ +class BitStream32LE : public BitStream { +public: + BitStream32LE(SeekableReadStream &stream, uint32 bitCount); + BitStream32LE(const byte *data, uint32 bitCount); + ~BitStream32LE(); + + uint32 getBit(); + uint32 getBits(uint32 n); + void addBit(uint32 &x, uint32 n); + + uint32 pos() const; + uint32 size() const; + +private: + SeekableReadStream *_stream; + + uint32 _value; ///< Current 32bit value. + uint8 _inValue; ///< Position within the current 32bit value. +}; + +} // End of namespace Common + +#endif // COMMON_BITSTREAM_H |