text: 
  /////////////////////////////////////////////////////////////////////
  // Mapper 49
  void NES_mapper49::Reset()
  {
    // set CPU bank pointers
    prg0 = 0;
    prg1 = 1;
    set_CPU_banks(0,1,2,3);
  
    // set VROM banks
    chr01 = 0;
    chr23 = 2;
    chr4  = 4;
    chr5  = 5;
    chr6  = 6;
    chr7  = 7;
    set_PPU_banks(0,1,2,3,4,5,6,7);
  
    regs[0] = regs[1] = regs[2] = 0;
    irq_enabled = 0;
    irq_counter = 0;
    irq_latch = 0;
  }
  
  void NES_mapper49::MemoryWriteSaveRAM(uint32 addr, uint8 data)
  {
    if(regs[2] & 0x80)
    {
      regs[1] = data;
      MMC3_set_CPU_banks();
      MMC3_set_PPU_banks();
    }
  }
  
  void NES_mapper49::MemoryWrite(uint32 addr, uint8 data)
  {
    switch(addr & 0xE001)
    {
      case 0x8000:
        {
          if((data & 0x40) != (regs[0] & 0x40))
          {
            MMC3_set_CPU_banks();
          }
          if((data & 0x80) != (regs[0] & 0x80))
          {
            regs[0] = data;
            MMC3_set_PPU_banks();
          }
          regs[0] = data;
        }
        break;
  
      case 0x8001:
        {
          switch(regs[0] & 0x07)
          {
            case 0x00:
              {
                chr01 = data & 0xFE;
                MMC3_set_PPU_banks();
              }
              break;
  
            case 0x01:
              {
                chr23 = data & 0xFE;
                MMC3_set_PPU_banks();
              }
              break;
  
            case 0x02:
              {
                chr4 = data;
                MMC3_set_PPU_banks();
              }
              break;
  
            case 0x03:
              {
                chr5 = data;
                MMC3_set_PPU_banks();
              }
              break;
  
            case 0x04:
              {
                chr6 = data;
                MMC3_set_PPU_banks();
              }
              break;
  
            case 0x05:
              {
                chr7 = data;
                MMC3_set_PPU_banks();
              }
              break;
  
            case 0x06:
              {
                prg0 = data;
                MMC3_set_CPU_banks();
              }
              break;
  
            case 0x07:
              {
                prg1 = data;
                MMC3_set_CPU_banks();
              }
              break;
          }
        }
        break;
  
      case 0xA000:
        {
          if(parent_NES->ROM->get_mirroring() != NES_PPU::MIRROR_FOUR_SCREEN)
          {
            if(data & 0x01)
            {
              set_mirroring(NES_PPU::MIRROR_HORIZ);
            }
            else
            {
              set_mirroring(NES_PPU::MIRROR_VERT);
            }
          }
        }
        break;
  
      case 0xA001:
        {
          regs[2] = data;
        }
        break;
  
      case 0xC000:
        {
          irq_counter = data;
        }
        break;
  
      case 0xC001:
        {
          irq_latch = data;
        }
        break;
  
      case 0xE000:
        {
          irq_enabled = 0;
        }
        break;
  
      case 0xE001:
        {
          irq_enabled = 1;
        }
        break;
    }
  }
  
  void NES_mapper49::HSync(uint32 scanline)
  {
    if(irq_enabled)
    {
      if((scanline >= 0) && (scanline <= 239))
      {
        if(parent_NES->ppu->spr_enabled() || parent_NES->ppu->bg_enabled())
        {
          if(!(irq_counter--))
          {
            irq_counter = irq_latch;
            parent_NES->cpu->DoIRQ();
          }
        }
      }
    }
  }
  
  void NES_mapper49::MMC3_set_CPU_banks()
  {
    if(regs[1] & 0x01)
    {
      if(regs[0] & 0x40)
      {
        set_CPU_bank4(((num_8k_ROM_banks - 1) & 0xE) | ((regs[1] & 0xC0) >> 2));
        set_CPU_bank5((prg1 & 0x0F) | ((regs[1] & 0xC0) >> 2));
        set_CPU_bank6((prg0 & 0x0F) | ((regs[1] & 0xC0) >> 2));
        set_CPU_bank7(((num_8k_ROM_banks - 1) & 0xF) | ((regs[1] & 0xC0) >> 2));
      }
      else
      {
        set_CPU_bank4((prg0 & 0x0F) | ((regs[1] & 0xC0) >> 2));
        set_CPU_bank5((prg1 & 0x0F) | ((regs[1] & 0xC0) >> 2));
        set_CPU_bank6(((num_8k_ROM_banks - 1) & 0xE) | ((regs[1] & 0xC0) >> 2));
        set_CPU_bank7(((num_8k_ROM_banks - 1) & 0xF) | ((regs[1] & 0xC0) >> 2));
      }
    }
    else
    {
      set_CPU_bank4(((regs[1] & 0x70) >> 2) | 0);
      set_CPU_bank5(((regs[1] & 0x70) >> 2) | 1);
      set_CPU_bank6(((regs[1] & 0x70) >> 2) | 2);
      set_CPU_bank7(((regs[1] & 0x70) >> 2) | 3);
    }
  }
  
  void NES_mapper49::MMC3_set_PPU_banks()
  {
    chr01 = (chr01 & 0x7F) | ((regs[1] & 0xC0) << 1);
    chr23 = (chr23 & 0x7F) | ((regs[1] & 0xC0) << 1);
    chr4 = (chr4 & 0x7F) | ((regs[1] & 0xC0) << 1);
    chr5 = (chr5 & 0x7F) | ((regs[1] & 0xC0) << 1);
    chr6 = (chr6 & 0x7F) | ((regs[1] & 0xC0) << 1);
    chr7 = (chr7 & 0x7F) | ((regs[1] & 0xC0) << 1);
  
    if(regs[0] & 0x80)
    {
      set_PPU_banks(chr4,chr5,chr6,chr7,chr01,chr01+1,chr23,chr23+1);
    }
    else
    {
      set_PPU_banks(chr01,chr01+1,chr23,chr23+1,chr4,chr5,chr6,chr7);
    }
  }
  
  #define MAP49_ROM(ptr)  (((ptr)-parent_NES->ROM->get_ROM_banks())  >> 13)
  #define MAP49_VROM(ptr) (((ptr)-parent_NES->ROM->get_VROM_banks()) >> 10)
  
  void NES_mapper49::SNSS_fixup()
  {
    NES_6502::Context context;
    parent_NES->cpu->GetContext(&context);
  
    if(regs[1])
    {
      prg0 = MAP49_ROM(context.mem_page[(regs[0] & 0x40) ? 6 : 4]);
      prg1 = MAP49_ROM(context.mem_page[5]);
    }
  
    if(regs[0] & 0x80)
    {
      chr01 = MAP49_VROM(parent_NES->ppu->PPU_VRAM_banks[4]);
      chr23 = MAP49_VROM(parent_NES->ppu->PPU_VRAM_banks[6]);
      chr4  = MAP49_VROM(parent_NES->ppu->PPU_VRAM_banks[0]);
      chr5  = MAP49_VROM(parent_NES->ppu->PPU_VRAM_banks[1]);
      chr6  = MAP49_VROM(parent_NES->ppu->PPU_VRAM_banks[2]);
      chr7  = MAP49_VROM(parent_NES->ppu->PPU_VRAM_banks[3]);
    }
    else
    {
      chr01 = MAP49_VROM(parent_NES->ppu->PPU_VRAM_banks[0]);
      chr23 = MAP49_VROM(parent_NES->ppu->PPU_VRAM_banks[2]);
      chr4  = MAP49_VROM(parent_NES->ppu->PPU_VRAM_banks[4]);
      chr5  = MAP49_VROM(parent_NES->ppu->PPU_VRAM_banks[5]);
      chr6  = MAP49_VROM(parent_NES->ppu->PPU_VRAM_banks[6]);
      chr7  = MAP49_VROM(parent_NES->ppu->PPU_VRAM_banks[7]);
    }
  }
  
  /////////////////////////////////////////////////////////////////////
  
  