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alexbevi
GitHub Repository: alexbevi/BizHawk
 Path: blob/master/libsnes/bsnes/gameboy/cartridge/mmm01/mmm01.cpp
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#ifdef CARTRIDGE_CPP

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uint8 Cartridge::MMM01::mmio_read(uint16 addr) {

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  if((addr & 0x8000) == 0x0000) {  //$0000-7fff

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    if(rom_mode == 0) return cartridge.rom_read(addr);

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  }

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  if((addr & 0xc000) == 0x0000) {  //$0000-3fff

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    return cartridge.rom_read(0x8000 + (rom_base << 14) + (addr & 0x3fff));

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  }

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  if((addr & 0xc000) == 0x4000) {  //$4000-7fff

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    return cartridge.rom_read(0x8000 + (rom_base << 14) + (rom_select << 14) + (addr & 0x3fff));

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  }

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  if((addr & 0xe000) == 0xa000) {  //$a000-bfff

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    if(ram_enable) return cartridge.ram_read((ram_select << 13) + (addr & 0x1fff));

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    return 0x00;

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  }

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  return 0x00;

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}

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void Cartridge::MMM01::mmio_write(uint16 addr, uint8 data) {

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  if((addr & 0xe000) == 0x0000) {  //$0000-1fff

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    if(rom_mode == 0) {

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      rom_mode = 1;

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    } else {

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      ram_enable = (data & 0x0f) == 0x0a;

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    }

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  }

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  if((addr & 0xe000) == 0x2000) {  //$2000-3fff

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    if(rom_mode == 0) {

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      rom_base = data & 0x3f;

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    } else {

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      rom_select = data;

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    }

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  }

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  if((addr & 0xe000) == 0x4000) {  //$4000-5fff

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    if(rom_mode == 1) {

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      ram_select = data;

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    }

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  }

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  if((addr & 0xe000) == 0x6000) {  //$6000-7fff

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    //unknown purpose

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  }

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  if((addr & 0xe000) == 0xa000) {  //$a000-bfff

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    if(ram_enable) cartridge.ram_write((ram_select << 13) + (addr & 0x1fff), data);

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  }

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}

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void Cartridge::MMM01::power() {

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  rom_mode = 0;

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  rom_base = 0;

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  ram_enable = false;

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  rom_select = 0x01;

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  ram_select = 0x00;

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}

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#endif

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