automatic crc32 calc; a couple extra helpers

stepmania/src/RageFile.cpp

@@ -97,6 +97,19 @@ int RageFile::PutLine( const CString &str )
 	return m_File->PutLine( str );
 }
 
+void RageFile::EnableCRC32( bool on )
+{
+	ASSERT_OPEN;
+	m_File->EnableCRC32( on );
+}
+
+bool RageFile::GetCRC32( unsigned *iRet )
+{
+	ASSERT_OPEN;
+	return m_File->GetCRC32( iRet );
+}
+
+
 bool RageFile::AtEOF() const
 {
 	ASSERT_READ;
@@ -203,6 +216,29 @@ void FileReading::ReadBytes( RageFileBasic &f, void *buf, int size, CString &sEr
 		sError = "Unexpected end of file";
 }
 
+void FileReading::SkipBytes( RageFileBasic &f, int iBytes, CString &sError )
+{
+	if( sError.size() != 0 )
+		return;
+
+	iBytes += f.Tell();
+	FileReading::Seek( f, iBytes, sError );
+}
+
+void FileReading::Seek( RageFileBasic &f, int iOffset, CString &sError )
+{
+	if( sError.size() != 0 )
+		return;
+
+	int iGot = f.Seek( iOffset );
+	if( iGot == iOffset )
+		return;
+	if( iGot == -1 )
+		sError = f.GetError();
+	else if( iGot < iOffset )
+		sError = "Unexpected end of file";
+}
+
 uint8_t FileReading::read_8( RageFileBasic &f, CString &sError )
 {
 	uint8_t val;

stepmania/src/RageFile.h

@@ -68,6 +68,9 @@ public:
 	int GetLine( CString &out );
 	int PutLine( const CString &str );
 
+	void EnableCRC32( bool on=true );
+	bool GetCRC32( unsigned *iRet );
+
 protected:
 	void SetError( const CString &err );
 	
@@ -84,6 +87,8 @@ namespace FileReading
 	/* On error, these set sError to the error message.  If sError is already
 	 * non-empty, nothing happens. */
 	void ReadBytes( RageFileBasic &f, void *buf, int size, CString &sError );
+	void SkipBytes( RageFileBasic &f, int size, CString &sError );
+	void Seek( RageFileBasic &f, int iOffset, CString &sError );
 	uint8_t read_8( RageFileBasic &f, CString &sError );
 	int16_t read_16_le( RageFileBasic &f, CString &sError );
 	uint16_t read_u16_le( RageFileBasic &f, CString &sError );

stepmania/src/RageFileBasic.cpp

@@ -11,6 +11,8 @@ RageFileObj::RageFileObj()
 	m_iBufAvail = 0;
 	m_bEOF = false;
 	m_iFilePos = 0;
+	m_bCRC32Enabled = false;
+	m_iCRC32 = 0;
 }
 
 RageFileObj::~RageFileObj()
@@ -27,6 +29,9 @@ int RageFileObj::Seek( int iOffset )
 
 	m_bEOF = false;
 
+	/* If we're calculating a CRC32, disable it. */
+	m_bCRC32Enabled = false;
+
 	ResetBuf();
 
 	int iPos = SeekInternal( iOffset );
@@ -58,6 +63,8 @@ int RageFileObj::Read( void *pBuffer, size_t iBytes )
 			/* Copy data out of the buffer first. */
 			int iFromBuffer = min( (int) iBytes, m_iBufAvail );
 			memcpy( pBuffer, m_pBuf, iFromBuffer );
+			if( m_bCRC32Enabled )
+				CRC32( m_iCRC32, pBuffer, iFromBuffer );
 
 			ret += iFromBuffer;
 			m_iFilePos += iFromBuffer;
@@ -85,6 +92,9 @@ int RageFileObj::Read( void *pBuffer, size_t iBytes )
 
 			if( iFromFile == 0 )
 				m_bEOF = true;
+
+			if( m_bCRC32Enabled )
+				CRC32( m_iCRC32, pBuffer, iFromFile );
 			ret += iFromFile;
 			m_iFilePos += iFromFile;
 			return ret;
@@ -147,7 +157,11 @@ int RageFileObj::Write( const void *pBuffer, size_t iBytes )
 {
 	int iRet = WriteInternal( pBuffer, iBytes );
 	if( iRet != -1 )
+	{
 		m_iFilePos += iRet;
+		if( m_bCRC32Enabled )
+			CRC32( m_iCRC32, pBuffer, iBytes );
+	}
 	return iRet;
 }
 
@@ -172,6 +186,32 @@ void RageFileObj::EnableBuffering()
 		m_pBuffer = new char[BSIZE];
 }
 
+void RageFileObj::EnableCRC32( bool on )
+{
+	if( !on )
+	{
+		m_bCRC32Enabled = false;
+		return;
+	}
+
+	/* If we're not at the beginning of the file, it's meaningless to start
+	 * calculating a CRC32 now. */
+	if( m_iFilePos != 0 )
+		return;
+
+	m_bCRC32Enabled = true;
+	m_iCRC32 = 0;
+}
+
+bool RageFileObj::GetCRC32( unsigned *iRet )
+{
+	if( !m_bCRC32Enabled )
+		return false;
+
+	*iRet = m_iCRC32;
+	return true;
+}
+
 /* Read up to the next \n, and return it in out.  Strip the \n.  If the \n is
  * preceded by a \r (DOS newline), strip that, too. */
 int RageFileObj::GetLine( CString &out )

stepmania/src/RageFileBasic.h

@@ -49,6 +49,9 @@ public:
 	virtual int GetLine( CString &out ) = 0;
 	virtual int PutLine( const CString &str ) = 0;
 
+	virtual void EnableCRC32( bool on=true ) = 0;
+	virtual bool GetCRC32( unsigned *iRet ) = 0;
+	
 	virtual int GetFileSize() const = 0;
 };
 
@@ -80,6 +83,9 @@ public:
 	int GetLine( CString &out );
 	int PutLine( const CString &str );
 
+	void EnableCRC32( bool on=true );
+	bool GetCRC32( unsigned *iRet );
+
 	virtual int GetFileSize() const = 0;
 	virtual CString GetDisplayPath() const { return ""; }
 	virtual RageFileBasic *Copy() const { FAIL_M( "Copying unimplemented" ); }
@@ -123,6 +129,12 @@ private:
 	char *m_pBuffer;
 	char *m_pBuf;
 	int  m_iBufAvail;
+
+	/* If EnableCRC32() is called, a CRC32 will be calculated as the file is read.
+	 * This is only meaningful if EnableCRC32() is called at the very start of the
+	 * file, and no seeking is performed. */
+	bool m_bCRC32Enabled;
+	unsigned m_iCRC32;
 };
 
 #endif