/*********************************************************************\

*This file is part of My Nes                                          *

*A Nintendo Entertainment System Emulator.                            *

*                                                                     *

*Copyright © Ala Hadid 2009 - 2011                                    *

*E-mail: mailto:ahdsoftwares@hotmail.com                              *

*                                                                     *

*My Nes 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.                                  *

*                                                                     *

*My Nes 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/>.*

\*********************************************************************/

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;



namespace MyNes.Nes

{

    class Mapper51:Mapper

    {

        int bank = 0;

        int mode = 1;

        public Mapper51(NesSystem nes) : base(nes) { }



        public override void Poke(int addr, byte data)

        {

            if (addr < 08000)

            {

                mode = ((data & 0x10) >> 3) | ((data & 0x02) >> 1);

                SetBank_CPU();

            }

            else

            {

                bank = (data & 0x0f) << 2;

                if (0xC000 <= addr && addr <= 0xDFFF)

                {

                    mode = (mode & 0x01) | ((data & 0x10) >> 3);

                }

                SetBank_CPU();

            } 

            base.Poke(addr, data);

        }

        protected override void Initialize(bool initializing)

        {

            cpuMemory.Map(0x6000, 0x7FFF, Poke);

            SetBank_CPU();

            if (cartridge.HasCharRam)

                cpuMemory.FillChr(16);

            cpuMemory.Switch8kChrRom(0);

            base.Initialize(initializing);

        }

        void SetBank_CPU()

        {

            switch (mode)

            {

                case 0:

                    cartridge.Mirroring = Mirroring.ModeVert;

                    cpuMemory.Switch8kPrgRomToSRAM((bank | 0x2c | 3) * 2);

                    cpuMemory.Switch8kPrgRom((bank | 0x00 | 0) * 2, 0);

                    cpuMemory.Switch8kPrgRom((bank | 0x00 | 1) * 2, 1);

                    cpuMemory.Switch8kPrgRom((bank | 0x0c | 2) * 2, 2);

                    cpuMemory.Switch8kPrgRom((bank | 0x0c | 3) * 2, 3);

                    break;

                case 1:

                    cartridge.Mirroring = Mirroring.ModeVert;

                    cpuMemory.Switch8kPrgRomToSRAM((bank | 0x20 | 3) * 2);

                    cpuMemory.Switch8kPrgRom((bank | 0x00 | 0) * 2, 0);

                    cpuMemory.Switch8kPrgRom((bank | 0x00 | 1) * 2, 1);

                    cpuMemory.Switch8kPrgRom((bank | 0x00 | 2) * 2, 2);

                    cpuMemory.Switch8kPrgRom((bank | 0x00 | 3) * 2, 3);

                    break;

                case 2:

                    cartridge.Mirroring = Mirroring.ModeVert;

                    cpuMemory.Switch8kPrgRomToSRAM((bank | 0x2e | 3) * 2);

                    cpuMemory.Switch8kPrgRom((bank | 0x02 | 0) * 2, 0);

                    cpuMemory.Switch8kPrgRom((bank | 0x02 | 1) * 2, 1);

                    cpuMemory.Switch8kPrgRom((bank | 0x0e | 2) * 2, 2);

                    cpuMemory.Switch8kPrgRom((bank | 0x0e | 3) * 2, 3);

                    break;

                case 3:

                    cartridge.Mirroring = Mirroring.ModeHorz;

                    cpuMemory.Switch8kPrgRomToSRAM((bank | 0x20 | 3) * 2);

                    cpuMemory.Switch8kPrgRom((bank | 0x00 | 0) * 2, 0);

                    cpuMemory.Switch8kPrgRom((bank | 0x00 | 1) * 2, 1);

                    cpuMemory.Switch8kPrgRom((bank | 0x00 | 2) * 2, 2);

                    cpuMemory.Switch8kPrgRom((bank | 0x00 | 3) * 2, 3);

                    break;

            }

        }



        public override void SaveState(StateStream stateStream)

        {

            stateStream.Write(bank);

            stateStream.Write(mode);

            base.SaveState(stateStream);

        }

        public override void LoadState(StateStream stateStream)

        {

            bank = stateStream.ReadInt32();

            mode = stateStream.ReadInt32();

            base.LoadState(stateStream);

        }

    }

}