026.cpp

来自「一个最快NFC的模拟器」· C++ 代码 · 共 154 行

/////////////////////////////////////////////////////////////////////
// Mapper 26
void NES_mapper26::Reset()
{
  // Init ExSound
  parent_NES->apu->SelectExSound(1);

  // set CPU bank pointers
  set_CPU_banks(0,1,num_8k_ROM_banks-2,num_8k_ROM_banks-1);

  // set PPU bank pointers
  if(num_1k_VROM_banks)
  {
    set_PPU_banks(0,1,2,3,4,5,6,7);
  }

  irq_enabled = 0;
  irq_counter = 0;
}

void NES_mapper26::MemoryWrite(uint32 addr, uint8 data)
{
  switch(addr)
  {
    case 0x8000:
      {
        set_CPU_bank4(data*2+0);
        set_CPU_bank5(data*2+1);
      }
      break;

    case 0xB003:
      {
        data = data & 0x7F;
        if(data == 0x08 || data == 0x2C)
        {
          set_mirroring(1,1,1,1);
        }
        else if(data == 0x20)
        {
          set_mirroring(NES_PPU::MIRROR_VERT);
        }
        else if(data == 0x24)
        {
          set_mirroring(NES_PPU::MIRROR_HORIZ);
        }
        else if(data == 0x28)
        {
          set_mirroring(0,0,0,0);
        }
      }
      break;

    case 0xC000:
      {
        set_CPU_bank6(data);
      }
      break;

    case 0xD000:
      {
        set_PPU_bank0(data);
      }
      break;

    case 0xD001:
      {
        set_PPU_bank2(data);
      }
      break;

    case 0xD002:
      {
        set_PPU_bank1(data);
      }
      break;

    case 0xD003:
      {
        set_PPU_bank3(data);
      }
      break;

    case 0xE000:
      {
        set_PPU_bank4(data);
      }
      break;

    case 0xE001:
      {
        set_PPU_bank6(data);
      }
      break;

    case 0xE002:
      {
        set_PPU_bank5(data);
      }
      break;

    case 0xE003:
      {
        set_PPU_bank7(data);
      }
      break;

    case 0xF000:
      {
        irq_latch = data;
      }
      break;

    case 0xF001:
      {
        irq_enabled = data & 0x01;
      }
      break;

    case 0xF002:
      {
        irq_enabled = data & 0x03;
        if(irq_enabled & 0x02)
        {
          irq_counter = irq_latch;
        }
      }
      break;
  }
  
  addr = addr & 0xfffc | ((addr & 1) << 1) | ((addr & 2) >> 1);
  parent_NES->apu->ExWrite(addr, data);
}

void NES_mapper26::HSync(uint32 scanline)
{
  if(irq_enabled & 0x03)
  {
    if(irq_counter >= 0xFE)
    {
      parent_NES->cpu->DoIRQ();
      irq_counter = irq_latch;
      irq_enabled = 0;
    }
    else
    {
      irq_counter++;
    }
  }
}
/////////////////////////////////////////////////////////////////////