COMMON: Add a BitStream class

Based on eos' BitStream

3 files changed, 318 insertions, 0 deletions

diff --git a/common/bitstream.cpp b/common/bitstream.cpp
new file mode 100644
index 0000000000..fb40957ef6
--- /dev/null
+++ b/common/bitstream.cpp
@@ -0,0 +1,215 @@
+/* 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
+
+#include "common/bitstream.h"
+#include "common/memstream.h"
+#include "common/stream.h"
+#include "common/textconsole.h"
+#include "common/util.h"
+
+namespace Common {
+
+BitStream::BitStream() {
+}
+
+BitStream::~BitStream() {
+}
+
+void BitStream::skip(uint32 n) {
+	while (n-- > 0)
+		getBit();
+}
+
+
+BitStreamBE::BitStreamBE(SeekableReadStream &stream, uint32 bitCount) : _value(0), _inValue(0) {
+	if ((bitCount % 8) != 0)
+		error("Big-endian bit stream size has to be divisible by 8");
+
+	// Read the number of bytes of the stream
+
+	uint32 byteSize = bitCount / 8;
+	byte *data = new byte[byteSize];
+
+	if (stream.read(data, byteSize) != byteSize) {
+		delete[] data;
+		error("Bad BitStreamBE size");
+	}
+}
+
+BitStreamBE::BitStreamBE(const byte *data, uint32 bitCount) : _value(0), _inValue(0) {
+	if ((bitCount % 8) != 0)
+		error("Big-endian bit stream size has to be divisible by 8");
+
+	// Copy the number of bytes from the data array
+
+	uint32 byteSize = bitCount / 8;
+	byte *dataN = new byte[byteSize];
+
+	memcpy(dataN, data, byteSize);
+
+	_stream = new MemoryReadStream(dataN, byteSize, DisposeAfterUse::YES);
+}
+
+BitStreamBE::~BitStreamBE() {
+	delete _stream;
+}
+
+uint32 BitStreamBE::getBit() {
+	if (_inValue == 0) {
+		// Need to get new byte
+
+		if (_stream->eos())
+			error("End of bit stream reached");
+
+		_value = _stream->readByte();
+	}
+
+	// Get the current bit
+	int b = ((_value & 0x80) == 0) ? 0 : 1;
+
+	// Shift to the next bit
+	_value <<= 1;
+
+	// Increase the position within the current byte
+	_inValue = (_inValue + 1) % 8;
+
+	return b;
+}
+
+uint32 BitStreamBE::getBits(uint32 n) {
+	if (n > 32)
+		error("Too many bits requested to be read");
+
+	// Read the number of bits
+	uint32 v = 0;
+	while (n-- > 0)
+		v = (v << 1) | getBit();
+
+	return v;
+}
+
+void BitStreamBE::addBit(uint32 &x, uint32 n) {
+	x = (x << 1) | getBit();
+}
+
+uint32 BitStreamBE::pos() const {
+	if (_stream->pos() == 0)
+		return 0;
+
+	uint32 p = (_inValue == 0) ? _stream->pos() : (_stream->pos() - 1);
+	return p * 8 + _inValue;
+}
+
+uint32 BitStreamBE::size() const {
+	return _stream->size() * 8;
+}
+
+
+BitStream32LE::BitStream32LE(SeekableReadStream &stream, uint32 bitCount) : _value(0), _inValue(0) {
+	if ((bitCount % 32) != 0)
+		error("32bit little-endian bit stream size has to be divisible by 32");
+
+	// Read the number of bytes of the stream
+
+	uint32 byteSize = bitCount / 8;
+	byte  *data     = new byte[byteSize];
+
+	if (stream.read(data, byteSize) != byteSize) {
+		delete[] data;
+		error("Bad BitStream32LE size");
+	}
+
+	_stream = new MemoryReadStream(data, byteSize, DisposeAfterUse::YES);
+}
+
+BitStream32LE::BitStream32LE(const byte *data, uint32 bitCount) : _value(0), _inValue(0) {
+	if ((bitCount % 32) != 0)
+		error("32bit little-endian bit stream size has to be divisible by 32");
+
+	// Copy the number of bytes from the data array
+
+	uint32 byteSize = bitCount / 8;
+	byte  *dataN    = new byte[byteSize];
+
+	memcpy(dataN, data, byteSize);
+
+	_stream = new MemoryReadStream(dataN, byteSize, DisposeAfterUse::YES);
+}
+
+BitStream32LE::~BitStream32LE() {
+	delete _stream;
+}
+
+uint32 BitStream32LE::getBit() {
+	if (_inValue == 0) {
+		// Need to get new 32bit value
+
+		if (_stream->eos())
+			error("End of bit stream reached");
+
+		_value = _stream->readUint32LE();
+	}
+
+	// Get the current bit
+	int b = ((_value & 1) == 0) ? 0 : 1;
+
+	// Shift to the next bit
+	_value >>= 1;
+
+	// Increase the position within the current byte
+	_inValue = (_inValue + 1) % 32;
+
+	return b;
+}
+
+uint32 BitStream32LE::getBits(uint32 n) {
+	if (n > 32)
+		error("Too many bits requested to be read");
+
+	// Read the number of bits
+	uint32 v = 0;
+	for (uint32 i = 0; i < n; i++)
+		v = (v >> 1) | (((uint32) getBit()) << 31);
+
+	v >>= (32 - n);
+	return v;
+}
+
+void BitStream32LE::addBit(uint32 &x, uint32 n) {
+	x = (x & ~(1 << n)) | (getBit() << n);
+}
+
+uint32 BitStream32LE::pos() const {
+	if (_stream->pos() == 0)
+		return 0;
+
+	uint32 p = ((_inValue == 0) ? _stream->pos() : (_stream->pos() - 1)) & 0xFFFFFFFC;
+	return p * 8 + _inValue;
+}
+
+uint32 BitStream32LE::size() const {
+	return _stream->size() * 8;
+}
+
+} // End of namespace Common
diff --git a/common/bitstream.h b/common/bitstream.h
new file mode 100644
index 0000000000..99aec252a3
--- /dev/null
+++ b/common/bitstream.h
@@ -0,0 +1,102 @@
+/* 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. */
+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
diff --git a/common/module.mk b/common/module.mk
index 5f6a529595..bada45bf91 100644
--- a/common/module.mk
+++ b/common/module.mk
@@ -2,6 +2,7 @@ MODULE := common
 
 MODULE_OBJS := \
 	archive.o \
+	bitstream.o \
 	config-file.o \
 	config-manager.o \
 	dcl.o \