player/Project/Src/NES/mapper/004.cpp

#include "nes_mapper.h" 

uint32 chr_swap() { return MAPx->regs[0] & 0x80; }
uint32 prg_swap() { return MAPx->regs[0] & 0x40; }
void MAP4_MMC3_set_CPU_banks(void);
void MAP4_MMC3_set_PPU_banks(void);
	
// Mapper 4
// much of this is based on the DarcNES source. thanks, nyef :)
void MAP4_Reset()
{ 
	int i;
  // clear registers FIRST!!!
  for( i = 0; i < 8; i++) MAPx->regs[i] = 0x00;
  // set CPU bank pointers
  MAPx->prg0 = 0;
  MAPx->prg1 = 1;
//  MAP4_MMC3_set_CPU_banks();

  // set VROM banks
  if(num_1k_VROM_banks)
  {
    MAPx->chr01 = 0;
    MAPx->chr23 = 2;
    MAPx->chr4  = 4;
    MAPx->chr5  = 5;
    MAPx->chr6  = 6;
    MAPx->chr7  = 7;
    MAP4_MMC3_set_PPU_banks();
  }
  else
  {
    MAPx->chr01 = MAPx->chr23 = MAPx->chr4 = MAPx->chr5 = MAPx->chr6 = MAPx->chr7 = 0;
  } 
  MAPx->irq_enabled = 0;
  MAPx->irq_counter = 0;
  MAPx->irq_latch = 0;
}

void MAP4_MemoryWrite(uint16 addr, uint8 data)
{
  switch(addr & 0xE001)
  {
    case 0x8000: 
      {
/*
        MAPx->regs[0] = data;
        MAP4_MMC3_set_PPU_banks();
        MAP4_MMC3_set_CPU_banks();
*/
		uint8 old = MAPx->regs[0];
		MAPx->regs[0] = data;
		
		if ((old & 0x40) != (data & 0x40)) {
			MAP4_MMC3_set_CPU_banks();
		}
		if ((old & 0x80) != (data & 0x80)) {
			MAP4_MMC3_set_PPU_banks();
		}
      }
      break;

    case 0x8001:
      {
        uint32 bank_num;

        MAPx->regs[1] = data;
        bank_num = MAPx->regs[1];

        switch(MAPx->regs[0] & 0x07)
        {
          case 0x00:
            {
              if(num_1k_VROM_banks)
              {
                bank_num &= 0xfe;
				if (MAPx->chr01 != bank_num) {
					MAPx->chr01 = bank_num;
					MAP4_MMC3_set_PPU_banks();
				}
              }
            }
            break;

          case 0x01:
            {
              if(num_1k_VROM_banks)
              {
                bank_num &= 0xfe;
				if (MAPx->chr23 != bank_num) {
					MAPx->chr23 = bank_num;
					MAP4_MMC3_set_PPU_banks();
				}
              }
            }
            break;

          case 0x02:
            {
              if(num_1k_VROM_banks)
              {
				if (MAPx->chr4 != bank_num) {
					MAPx->chr4 = bank_num;
					MAP4_MMC3_set_PPU_banks();
				}
              }
            }
            break;

          case 0x03:
            {
              if(num_1k_VROM_banks)
              {
				if (MAPx->chr5 != bank_num) {
					MAPx->chr5 = bank_num;
					MAP4_MMC3_set_PPU_banks();
				}
              }
            }
            break;

          case 0x04:
            {
              if(num_1k_VROM_banks)
              {
				if (MAPx->chr6 != bank_num) {
					MAPx->chr6 = bank_num;
					MAP4_MMC3_set_PPU_banks();
				}
              }
            }
            break;

          case 0x05:
            {
              if(num_1k_VROM_banks)
              {
				if (MAPx->chr7 != bank_num) {
					MAPx->chr7 = bank_num;
					MAP4_MMC3_set_PPU_banks();
				}
              }
            }
            break;

          case 0x06:
            {
			  if (MAPx->prg0 != bank_num) {
				  MAPx->prg0 = bank_num;
				  MAP4_MMC3_set_CPU_banks();
			  }
            }
            break;

          case 0x07:
            {
			  if (MAPx->prg1 != bank_num) {
				  MAPx->prg1 = bank_num;
				  MAP4_MMC3_set_CPU_banks();
			  }
            }
            break;
        }
      }
      break;

    case 0xA000:
      {
        MAPx->regs[2] = data;

        if(data & 0x40)
        {
          //LOG("MAPx MIRRORING: 0x40 ???" << endl);
        }

        //if(parent_NES->ROM->get_mirroring() != NES_PPU::MIRROR_FOUR_SCREEN)
		if ( !(RomHeader->flags_1&0x8 ))
        {
          if(data & 0x01)
          {
				set_mirroring(0,0,1,1);//ˮƽ<CBAE><C6BD><EFBFBD><EFBFBD>
				//set_mirroring(NES_PPU::MIRROR_HORIZ);
          }
          else
          {
				set_mirroring(0,1,0,1);//<2F><>ֱ<EFBFBD><D6B1><EFBFBD><EFBFBD>
				//set_mirroring(NES_PPU::MIRROR_VERT);
          }
        }
      }
      break;

    case 0xA001:
      {
        MAPx->regs[3] = data;

        if(data & 0x80)
        {
          // enable save RAM $6000-$7FFF
        }
        else
        {
          // disable save RAM $6000-$7FFF
        }
      }
      break;

    case 0xC000:
      MAPx->regs[4] = data;
      MAPx->irq_counter = MAPx->regs[4];
      break;

    case 0xC001:
      MAPx->regs[5] = data;
      MAPx->irq_latch = MAPx->regs[5];
      break;

    case 0xE000:
      MAPx->regs[6] = data;
      MAPx->irq_enabled = 0;
      break;

    case 0xE001:
      MAPx->regs[7] = data;
      MAPx->irq_enabled = 1;
      break;

    default:
      //LOG("MAPx: UNKNOWN: " << HEX(addr,4) << " = " << HEX(data) << endl);
      break;

  }
}

void MAP4_HSync(int scanline)
{
  if(MAPx->irq_enabled)
  {
    if((scanline >= 0) && (scanline <= 239)&&( spr_enabled() || bg_enabled()))
    {
      //if(parent_NES->ppu->spr_enabled() || parent_NES->ppu->bg_enabled())
      {
//        if(patch == 1)
//        {
//          if(!(--MAPx->irq_counter))
//          {
//            MAPx->irq_counter = MAPx->irq_latch;
//            parent_NES->cpu->DoIRQ();
//          }
//        }
//        else if(patch == 2)
//        {
//          if(--MAPx->irq_counter == 0x01)
//          {
//            MAPx->irq_counter = MAPx->irq_latch;
//            parent_NES->cpu->DoIRQ();
//          }
//        }
//        else
        {
          if(!(MAPx->irq_counter--))
          {
            MAPx->irq_counter = MAPx->irq_latch;
            CPU_IRQ;
          }
        }
      }
    }
  }
}

void MAP4_MMC3_set_CPU_banks()
{
  if(prg_swap())
  {
    set_CPU_banks(-2,MAPx->prg1,MAPx->prg0,-1);
  }
  else
  {
    set_CPU_banks(MAPx->prg0,MAPx->prg1,-2,-1);
  }
}

void MAP4_MMC3_set_PPU_banks()
{
  if(num_1k_VROM_banks)
  {
    if(chr_swap())
    {
      set_PPU_banks(MAPx->chr4,MAPx->chr5,MAPx->chr6,MAPx->chr7,MAPx->chr01,MAPx->chr01+1,MAPx->chr23,MAPx->chr23+1);
    }
    else
    {
      set_PPU_banks(MAPx->chr01,MAPx->chr01+1,MAPx->chr23,MAPx->chr23+1,MAPx->chr4,MAPx->chr5,MAPx->chr6,MAPx->chr7);
    }
  }
  else
  {
    if(chr_swap())
    {
      set_VRAM_bank(0, MAPx->chr4);
      set_VRAM_bank(1, MAPx->chr5);
      set_VRAM_bank(2, MAPx->chr6);
      set_VRAM_bank(3, MAPx->chr7);
      set_VRAM_bank(4, MAPx->chr01+0);
      set_VRAM_bank(5, MAPx->chr01+1);
      set_VRAM_bank(6, MAPx->chr23+0);
      set_VRAM_bank(7, MAPx->chr23+1);
    }
    else
    {
      set_VRAM_bank(0, MAPx->chr01+0);
      set_VRAM_bank(1, MAPx->chr01+1);
      set_VRAM_bank(2, MAPx->chr23+0);
      set_VRAM_bank(3, MAPx->chr23+1);
      set_VRAM_bank(4, MAPx->chr4);
      set_VRAM_bank(5, MAPx->chr5);
      set_VRAM_bank(6, MAPx->chr6);
      set_VRAM_bank(7, MAPx->chr7);
    }
  }
}
void MAP4_Init()
{
	NES_Mapper->Reset = MAP4_Reset;
	NES_Mapper->Write = MAP4_MemoryWrite; 
	NES_Mapper->HSync = MAP4_HSync;
}