nestopia/source/core/NstState.cpp

////////////////////////////////////////////////////////////////////////////////////////
//
// Nestopia - NES/Famicom emulator written in C++
//
// Copyright (C) 2003-2008 Martin Freij
//
// This file is part of Nestopia.
//
// Nestopia 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.
//
// Nestopia 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 Nestopia; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
//
////////////////////////////////////////////////////////////////////////////////////////

#include "NstState.hpp"
#include "NstZlib.hpp"

namespace Nes
{
	namespace Core
	{
		namespace State
		{
			enum Compression
			{
				NO_COMPRESSION,
				ZLIB_COMPRESSION
			};

			#ifdef NST_MSVC_OPTIMIZE
			#pragma optimize("s", on)
			#endif

			Saver::Saver(StdStream p,bool c,bool i,dword append)
			: stream(p), chunks(CHUNK_RESERVE), useCompression(c), internal(i)
			{
				NST_COMPILE_ASSERT( CHUNK_RESERVE >= 2 );

				chunks.SetTo(1);
				chunks.Front() = 0;

				if (append)
				{
					chunks.SetTo(2);
					chunks[1] = append;
					stream.Seek( 4 + 4 + append );
				}
			}

			Saver::~Saver()
			{
				NST_VERIFY( chunks.Size() == 1 );
			}

			#ifdef NST_MSVC_OPTIMIZE
			#pragma optimize("", on)
			#endif

			Saver& Saver::Begin(dword chunk)
			{
				stream.Write32( chunk );
				stream.Write32( 0 );
				chunks.Append( 0 );

				return *this;
			}

			Saver& Saver::End()
			{
				NST_ASSERT( chunks.Size() > 1 );

				const dword written = chunks.Pop();
				chunks.Back() += 4 + 4 + written;

				stream.Seek( -idword(written + 4) );
				stream.Write32( written );
				stream.Seek( written );

				return *this;
			}

			Saver& Saver::Write8(uint data)
			{
				chunks.Back() += 1;
				stream.Write8( data );
				return *this;
			}

			Saver& Saver::Write16(uint data)
			{
				chunks.Back() += 2;
				stream.Write16( data );
				return *this;
			}

			Saver& Saver::Write32(dword data)
			{
				chunks.Back() += 4;
				stream.Write32( data );
				return *this;
			}

			Saver& Saver::Write64(qaword data)
			{
				chunks.Back() += 8;
				stream.Write64( data );
				return *this;
			}

			Saver& Saver::Write(const byte* data,dword length)
			{
				chunks.Back() += length;
				stream.Write( data, length );
				return *this;
			}

			Saver& Saver::Compress(const byte* const data,const dword length)
			{
				NST_VERIFY( length );

				if (Zlib::AVAILABLE && useCompression && length > 1)
				{
					Vector<byte> buffer( length - 1 );

					if (const dword compressed = Zlib::Compress( data, length, buffer.Begin(), buffer.Size(), Zlib::BEST_COMPRESSION ))
					{
						chunks.Back() += 1 + compressed;
						stream.Write8( ZLIB_COMPRESSION );
						stream.Write( buffer.Begin(), compressed );
						return *this;
					}
				}

				chunks.Back() += 1 + length;
				stream.Write8( NO_COMPRESSION );
				stream.Write( data, length );

				return *this;
			}

			#ifdef NST_MSVC_OPTIMIZE
			#pragma optimize("s", on)
			#endif

			Loader::Loader(StdStream p,bool c)
			: stream(p), chunks(CHUNK_RESERVE), checkCrc(c)
			{
				chunks.SetTo(0);
			}

			Loader::~Loader()
			{
				NST_VERIFY( chunks.Size() <= 1 );
			}

			#ifdef NST_MSVC_OPTIMIZE
			#pragma optimize("", on)
			#endif

			dword Loader::Begin()
			{
				if (chunks.Size() && !chunks.Back())
					return 0;

				const dword chunk = stream.Read32();
				const dword length = stream.Read32();

				if (chunks.Size())
				{
					if (chunks.Back() >= 4+4+length)
						chunks.Back() -= 4+4+length;
					else
						throw RESULT_ERR_CORRUPT_FILE;
				}

				chunks.Append( length );

				return chunk;
			}

			dword Loader::Length() const
			{
				return chunks.Size() ? chunks.Back() : 0;
			}

			dword Loader::Check()
			{
				return chunks.Size() && !chunks.Back() ? 0 : stream.Peek32();
			}

			void Loader::End()
			{
				if (const dword remaining = chunks.Pop())
				{
					NST_DEBUG_MSG("unreferenced state chunk data!");
					stream.Seek( remaining );
				}
			}

			void Loader::End(dword rollBack)
			{
				if (const idword back = -idword(rollBack+4+4) + idword(chunks.Pop()))
					stream.Seek( back );
			}

			void Loader::CheckRead(dword length)
			{
				if (chunks.Back() >= length)
					chunks.Back() -= length;
				else
					throw RESULT_ERR_CORRUPT_FILE;
			}

			uint Loader::Read8()
			{
				CheckRead( 1 );
				return stream.Read8();
			}

			uint Loader::Read16()
			{
				CheckRead( 2 );
				return stream.Read16();
			}

			dword Loader::Read32()
			{
				CheckRead( 4 );
				return stream.Read32();
			}

			qaword Loader::Read64()
			{
				CheckRead( 8 );
				return stream.Read64();
			}

			void Loader::Read(byte* const data,const dword length)
			{
				CheckRead( length );
				stream.Read( data, length );
			}

			void Loader::Uncompress(byte* const data,const dword length)
			{
				NST_VERIFY( length );

				switch (Read8())
				{
					case NO_COMPRESSION:

						Read( data, length );
						break;

					case ZLIB_COMPRESSION:

						if (!Zlib::AVAILABLE)
						{
							throw RESULT_ERR_UNSUPPORTED;
						}
						else if (chunks.Back())
						{
							Vector<byte> buffer( chunks.Back() );
							Read( buffer.Begin(), buffer.Size() );

							if (Zlib::Uncompress( buffer.Begin(), buffer.Size(), data, length ))
								break;
						}

					default:

						throw RESULT_ERR_CORRUPT_FILE;
				}
			}
		}
	}
}