/*==LICENSE==*

CyanWorlds.com Engine - MMOG client, server and tools
Copyright (C) 2011 Cyan Worlds, Inc.

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 3 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, see <http://www.gnu.org/licenses/>.

Additional permissions under GNU GPL version 3 section 7

If you modify this Program, or any covered work, by linking or
combining it with any of RAD Game Tools Bink SDK, Autodesk 3ds Max SDK,
NVIDIA PhysX SDK, Microsoft DirectX SDK, OpenSSL library, Independent
JPEG Group JPEG library, Microsoft Windows Media SDK, or Apple QuickTime SDK
(or a modified version of those libraries),
containing parts covered by the terms of the Bink SDK EULA, 3ds Max EULA,
PhysX SDK EULA, DirectX SDK EULA, OpenSSL and SSLeay licenses, IJG
JPEG Library README, Windows Media SDK EULA, or QuickTime SDK EULA, the
licensors of this Program grant you additional
permission to convey the resulting work. Corresponding Source for a
non-source form of such a combination shall include the source code for
the parts of OpenSSL and IJG JPEG Library used as well as that of the covered
work.

You can contact Cyan Worlds, Inc. by email legal@cyan.com
 or by snail mail at:
      Cyan Worlds, Inc.
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*==LICENSE==*/
//////////////////////////////////////////////////////////////////////////////
//
//	plDiffBuffer - A utility class for writing and applying a difference
//				   buffer--i.e. a buffer containing a series of modifications
//				   (specifically, adds and copys) that will modify an old
//				   data buffer to match a new one. It's a useful utility
//				   class when doing binary file patching, for example, as you
//				   can write out the changes to this class, get back a data
//				   buffer suitable for writing, then use this class again
//				   later to reconstruct the new buffer.
//
//					This class is meant to construct diff buffers using two
//					ops: add and copy. Basically, the syntax is defined so
//					that to reconstruct the new buffer, you run through the 
//					list of ops sequentially, each one defining the next
//					chunk of data in the new buffer. Add ops will add new data
//					to the buffer that didn't exist in the old buffer, and 
//					copy ops will copy data that existed in the old buffer
//					(from an arbitrary offset, to facilitate encoding data
//					shuffling). Delete ops are implicit, as they simply aren't
//					defined in the stream of ops.
//
//// History /////////////////////////////////////////////////////////////////
//
//	7.24.2002 mcn	- Created (Happy late b-day to me!)
//
//////////////////////////////////////////////////////////////////////////////

#ifndef _plDiffBuffer_h
#define _plDiffBuffer_h

#include "hsTypes.h"
#include "hsStream.h"

//// Class Definition ////////////////////////////////////////////////////////

class hsRAMStream;
class plBSDiffBuffer;
class plDiffBuffer
{
	protected:

		hsBool		fWriting, f16BitMode;
		UInt32		fNewLength;
		hsRAMStream	*fStream;
		
		// Support for BSDiff patch buffers (Patching only)
		plBSDiffBuffer	*fBSDiffBuffer;
		hsBool			fIsBSDiff;

	public:

		plDiffBuffer( UInt32 newLength, UInt32 oldLength = 0 );		// Constructor for writing new buffers. oldLength isn't required but helpful for optimizations
		plDiffBuffer( void *buffer, UInt32 length );	// Constructor for applying a given diff set
														// to an old buffer
		virtual ~plDiffBuffer();


		/// Creation/write functions

		// Add() appends an Add-New-Data operation to the diff buffer. The data supplied will be copied internally.
		void	Add( Int32 length, void *newData );

		// Copy() appends a Copy-Data-From-Old operation to the diff buffer
		void	Copy( Int32 length, UInt32 oldOffset );

		// GetBuffer() will copy the diff stream into a new buffer and return it. You are responsible for freeing the buffer.
		void	GetBuffer( UInt32 &length, void *&bufferPtr );


		/// Apply functions

		// Apply() will take this diff buffer and apply it to the given old buffer, allocating and producing a new buffer. You are responsible for freeing the new buffer.
		void	Apply( UInt32 oldLength, void *oldBuffer, UInt32 &newLength, void *&newBuffer );

};

#endif // _plDiffBuffer_h