//////////////////
// Mapper021  Konami VRC4 (Address mask $F006 or $F0C0)                 //
//////////////////////////////////////////////////////////////////////////
using static VirtualNes.Core.CPU;
using static VirtualNes.MMU;
using BYTE = System.Byte;
using INT = System.Int32;


namespace VirtualNes.Core
{
    public class Mapper021 : Mapper
    {
        BYTE[] reg = new byte[9];

        BYTE irq_enable;
        BYTE irq_counter;
        BYTE irq_latch;
        INT irq_clock;
        public Mapper021(NES parent) : base(parent)
        {
        }


        public override void Reset()
        {
            for (byte i = 0; i < 8; i++)
            {
                reg[i] = i;
            }
            reg[8] = 0;

            irq_enable = 0;
            irq_counter = 0;
            irq_latch = 0;
            irq_clock = 0;

            SetPROM_32K_Bank(0, 1, PROM_8K_SIZE - 2, PROM_8K_SIZE - 1);
        }

        //void Mapper021::Write(WORD addr, BYTE data)
        public override void Write(ushort addr, byte data)
        {
            switch (addr & 0xF0CF)
            {
                case 0x8000:
                    if ((reg[8] & 0x02) != 0)
                    {
                        SetPROM_8K_Bank(6, data);
                    }
                    else
                    {
                        SetPROM_8K_Bank(4, data);
                    }
                    break;
                case 0xA000:
                    SetPROM_8K_Bank(5, data);
                    break;

                case 0x9000:
                    data &= 0x03;
                    if (data == 0) SetVRAM_Mirror(VRAM_VMIRROR);
                    else if (data == 1) SetVRAM_Mirror(VRAM_HMIRROR);
                    else if (data == 2) SetVRAM_Mirror(VRAM_MIRROR4L);
                    else SetVRAM_Mirror(VRAM_MIRROR4H);
                    break;

                case 0x9002:
                case 0x9080:
                    reg[8] = data;
                    break;

                case 0xB000:
                    reg[0] = (byte)((reg[0] & 0xF0) | (data & 0x0F));
                    SetVROM_1K_Bank(0, reg[0]);
                    break;
                case 0xB002:
                case 0xB040:
                    reg[0] = (byte)((reg[0] & 0x0F) | ((data & 0x0F) << 4));
                    SetVROM_1K_Bank(0, reg[0]);
                    break;

                case 0xB001:
                case 0xB004:
                case 0xB080:
                    reg[1] = (byte)((reg[1] & 0xF0) | (data & 0x0F));
                    SetVROM_1K_Bank(1, reg[1]);
                    break;
                case 0xB003:
                case 0xB006:
                case 0xB0C0:
                    reg[1] = (byte)((reg[1] & 0x0F) | ((data & 0x0F) << 4));
                    SetVROM_1K_Bank(1, reg[1]);
                    break;

                case 0xC000:
                    reg[2] = (byte)((reg[2] & 0xF0) | (data & 0x0F));
                    SetVROM_1K_Bank(2, reg[2]);
                    break;
                case 0xC002:
                case 0xC040:
                    reg[2] = (byte)((reg[2] & 0x0F) | ((data & 0x0F) << 4));
                    SetVROM_1K_Bank(2, reg[2]);
                    break;

                case 0xC001:
                case 0xC004:
                case 0xC080:
                    reg[3] = (byte)((reg[3] & 0xF0) | (data & 0x0F));
                    SetVROM_1K_Bank(3, reg[3]);
                    break;
                case 0xC003:
                case 0xC006:
                case 0xC0C0:
                    reg[3] = (byte)((reg[3] & 0x0F) | ((data & 0x0F) << 4));
                    SetVROM_1K_Bank(3, reg[3]);
                    break;

                case 0xD000:
                    reg[4] = (byte)((reg[4] & 0xF0) | (data & 0x0F));
                    SetVROM_1K_Bank(4, reg[4]);
                    break;
                case 0xD002:
                case 0xD040:
                    reg[4] = (byte)((reg[4] & 0x0F) | ((data & 0x0F) << 4));
                    SetVROM_1K_Bank(4, reg[4]);
                    break;

                case 0xD001:
                case 0xD004:
                case 0xD080:
                    reg[5] = (byte)((reg[5] & 0xF0) | (data & 0x0F));
                    SetVROM_1K_Bank(5, reg[5]);
                    break;
                case 0xD003:
                case 0xD006:
                case 0xD0C0:
                    reg[5] = (byte)((reg[5] & 0x0F) | ((data & 0x0F) << 4));
                    SetVROM_1K_Bank(5, reg[5]);
                    break;

                case 0xE000:
                    reg[6] = (byte)((reg[6] & 0xF0) | (data & 0x0F));
                    SetVROM_1K_Bank(6, reg[6]);
                    break;
                case 0xE002:
                case 0xE040:
                    reg[6] = (byte)((reg[6] & 0x0F) | ((data & 0x0F) << 4));
                    SetVROM_1K_Bank(6, reg[6]);
                    break;

                case 0xE001:
                case 0xE004:
                case 0xE080:
                    reg[7] = (byte)((reg[7] & 0xF0) | (data & 0x0F));
                    SetVROM_1K_Bank(7, reg[7]);
                    break;
                case 0xE003:
                case 0xE006:
                case 0xE0C0:
                    reg[7] = (byte)((reg[7] & 0x0F) | ((data & 0x0F) << 4));
                    SetVROM_1K_Bank(7, reg[7]);
                    break;

                case 0xF000:
                    irq_latch = (byte)((irq_latch & 0xF0) | (data & 0x0F));
                    break;
                case 0xF002:
                case 0xF040:
                    irq_latch = (byte)((irq_latch & 0x0F) | ((data & 0x0F) << 4));
                    break;

                case 0xF003:
                case 0xF0C0:
                case 0xF006:
                    irq_enable = (byte)((irq_enable & 0x01) * 3);
                    irq_clock = 0;

                    nes.cpu.ClrIRQ(IRQ_MAPPER);
                    break;

                case 0xF004:
                case 0xF080:
                    irq_enable = (byte)(data & 0x03);
                    if ((irq_enable & 0x02) != 0)
                    {
                        irq_counter = irq_latch;
                        irq_clock = 0;
                    }

                    nes.cpu.ClrIRQ(IRQ_MAPPER);
                    break;

                    //		case 0xF006:
                    //			nes.cpu.ClrIRQ( IRQ_MAPPER );
                    //			break;
            }
        }

        //void Mapper021::Clock(INT cycles)
        public override void Clock(int cycles)
        {
            if ((irq_enable & 0x02) != 0)
            {
                if ((irq_clock -= cycles) < 0)
                {
                    irq_clock += 0x72;
                    if (irq_counter == 0xFF)
                    {
                        irq_counter = irq_latch;
                        //				irq_enable = (irq_enable & 0x01) * 3;
                        //				nes.cpu.IRQ_NotPending();
                        nes.cpu.SetIRQ(IRQ_MAPPER);
                    }
                    else
                    {
                        irq_counter++;
                    }
                }
            }
        }

        //void Mapper021::SaveState(LPBYTE p)
        public override void SaveState(byte[] p)
        {
            //for (INT i = 0; i < 9; i++)
            //{
            //	p[i] = reg[i];
            //}
            //p[9] = irq_enable;
            //p[10] = irq_counter;
            //p[11] = irq_latch;
            //*(INT*)&p[12] = irq_clock;
        }

        //void Mapper021::LoadState(LPBYTE p)
        public override void LoadState(byte[] p)
        {
            //for (INT i = 0; i < 9; i++)
            //{
            //	reg[i] = p[i];
            //}
            //irq_enable = p[9];
            //irq_counter = p[10];
            //irq_latch = p[11];
            //irq_clock = *(INT*)&p[12];
        }


        public override bool IsStateSave()
        {
            return true;
        }
    }
}