Fixed broken bitstream parsing

+ refactoring

src/map/IMG/bitstream.cpp

@@ -41,16 +41,15 @@ bool BitStream4F::flush()
 	return true;
 }
 
-bool BitStream4F::read(int bits, quint32 &val)
+bool BitStream4F::read(quint32 bits, quint32 &val)
 {
-	if (bits <= 32 - (int)(_used + _unused)) {
+	if (bits <= 32 - (_used + _unused)) {
 		val = bits ? (_data << _used) >> (32 - bits) : 0;
 		_used += bits;
 		return true;
 	}
 
-	if (_unused)
+	Q_ASSERT(_length && !_unused);
-		return false;
 	quint32 old = (_used < 32) ? (_data << _used) >> (32 - bits) : 0;
 	quint32 bytes = qMin(_length, 4U);
 
@@ -73,7 +72,7 @@ BitStream4R::BitStream4R(const SubFile &file, SubFile::Handle &hdl,
 	_file.seek(_hdl, _file.pos(_hdl) - 4);
 }
 
-bool BitStream4R::readBytes(int bytes, quint32 &val)
+bool BitStream4R::readBytes(quint32 bytes, quint32 &val)
 {
 	quint32 bits = _used % 8;
 	quint32 b;
@@ -85,7 +84,7 @@ bool BitStream4R::readBytes(int bytes, quint32 &val)
 	}
 
 	val = 0;
-	for (int i = 0; i < bytes; i++) {
+	for (quint32 i = 0; i < bytes; i++) {
 		if (!read(8, b))
 			return false;
 		val |= (b << (i * 8));

src/map/IMG/bitstream.h

@@ -10,7 +10,7 @@ public:
 	BitStream1(const SubFile &file, SubFile::Handle &hdl, quint32 length)
 	  : _file(file), _hdl(hdl), _length(length), _remaining(0) {}
 
-	template<typename T> bool read(int bits, T &val);
+	template<typename T> bool read(quint32 bits, T &val);
 	bool flush();
 	quint64 bitsAvailable() const {return (quint64)_length * 8 + _remaining;}
 
@@ -44,7 +44,7 @@ public:
 	BitStream4F(const SubFile &file, SubFile::Handle &hdl, quint32 length)
 	  : BitStream4(file, hdl, length) {}
 
-	bool read(int bits, quint32 &val);
+	bool read(quint32 bits, quint32 &val);
 	bool flush();
 };
 
@@ -60,8 +60,8 @@ public:
 
 	BitStream4R(const SubFile &file, SubFile::Handle &hdl, quint32 length);
 
-	template<typename T> bool read(int bits, T &val);
+	template<typename T> bool read(quint32 bits, T &val);
-	bool readBytes(int bytes, quint32 &val);
+	bool readBytes(quint32 bytes, quint32 &val);
 	bool readVUInt32(quint32 &val);
 	bool readVuint32SM(quint32 &val1, quint32 &val2, quint32 &val2Bits);
 
@@ -73,11 +73,11 @@ public:
 
 
 template<typename T>
-bool BitStream1::read(int bits, T &val)
+bool BitStream1::read(quint32 bits, T &val)
 {
 	val = 0;
 
-	for (int pos = 0; pos < bits; ) {
+	for (quint32 pos = 0; pos < bits; ) {
 		if (!_remaining) {
 			if (!_length || !_file.readByte(_hdl, &_data))
 				return false;
@@ -103,16 +103,15 @@ bool BitStream1::read(int bits, T &val)
 }
 
 template<typename T>
-bool BitStream4R::read(int bits, T &val)
+bool BitStream4R::read(quint32 bits, T &val)
 {
-	if (bits <= 32 - (int)(_used + _unused)) {
+	if (bits <= 32 - (_used + _unused)) {
 		val = bits ? (_data << _used) >> (32 - bits) : 0;
 		_used += bits;
 		return true;
 	}
 
-	if (_unused)
+	Q_ASSERT(_length && !_unused);
-		return false;
 	quint32 old = (_used < 32) ? (_data << _used) >> (32 - bits) : 0;
 	quint32 bytes = qMin(_length, 4U);
 

src/map/IMG/huffmanstream.h

@@ -12,7 +12,7 @@ public:
 	HuffmanStream(BitStream &bitstream, const HuffmanTable &table)
 	  : _symbolDataSize(0), _symbolData(0), _bs(bitstream), _table(table) {}
 
-	bool read(int bits, quint32 &val);
+	bool read(quint32 bits, quint32 &val);
 	bool readSymbol(quint32 &symbol);
 
 	bool atEnd() const
@@ -24,29 +24,35 @@ protected:
 	quint32 _symbolData;
 
 private:
+	bool fetchData();
+
 	BitStream &_bs;
 	const HuffmanTable &_table;
 };
 
 template <class BitStream>
-bool HuffmanStream<BitStream>::read(int bits, quint32 &val)
+bool HuffmanStream<BitStream>::fetchData()
 {
-	if (_symbolDataSize < (quint32)bits) {
+	quint32 next;
-		quint32 next;
+	quint8 nextSize = qMin((quint64)(32 - _symbolDataSize), _bs.bitsAvailable());
-		quint8 nextSize = qMin((quint64)(32 - _symbolDataSize),
-		  _bs.bitsAvailable());
 
-		if (!_bs.read(nextSize, next))
+	if (!_bs.read(nextSize, next))
+		return false;
+
+	_symbolData = (nextSize < 32) ? (_symbolData << nextSize) | next : next;
+	_symbolDataSize += nextSize;
+
+	return true;
+}
+
+template <class BitStream>
+bool HuffmanStream<BitStream>::read(quint32 bits, quint32 &val)
+{
+	if (_symbolDataSize < bits)
+		if (!fetchData() || _symbolDataSize < bits)
 			return false;
 
-		_symbolData = (_symbolData << nextSize) | next;
+	val = (_symbolData << (32 - _symbolDataSize)) >> (32 - bits);
-		_symbolDataSize += nextSize;
-
-		if (_symbolDataSize < (quint32)bits)
-			return false;
-	}
-
-	val = (_symbolData << (32-_symbolDataSize)) >> (32 - bits);
 	_symbolDataSize -= bits;
 
 	return true;
@@ -57,18 +63,10 @@ bool HuffmanStream<BitStream>::readSymbol(quint32 &symbol)
 {
 	quint8 size;
 
-	if (_symbolDataSize < _table.symBits()) {
+	if (_symbolDataSize < _table.symBits())
-		quint32 next;
+		if (!fetchData() || !_symbolDataSize)
-		quint8 nextSize = qMin((quint64)(32 - _symbolDataSize),
-		  _bs.bitsAvailable());
-
-		if (!_bs.read(nextSize, next))
 			return false;
 
-		_symbolData = (_symbolData << nextSize) | next;
-		_symbolDataSize += nextSize;
-	}
-
 	symbol = _table.symbol(_symbolData << (32 - _symbolDataSize), size);
 	if (size > _symbolDataSize)
 		return false;