bsnes/fc/cartridge/board/nes-gxrom.cpp

//NES-GNROM
//NES-MHROM

struct NES_GxROM : Board {

struct Settings {
  bool mirror;  //0 = horizontal, 1 = vertical
} settings;

uint2 prg_bank;
uint2 chr_bank;

uint8 prg_read(unsigned addr) {
  if(addr & 0x8000) return prgrom.read((prg_bank << 15) | (addr & 0x7fff));
  return cpu.mdr();
}

void prg_write(unsigned addr, uint8 data) {
  if(addr & 0x8000) {
    prg_bank = (data & 0x30) >> 4;
    chr_bank = (data & 0x03) >> 0;
  }
}

uint8 chr_read(unsigned addr) {
  if(addr & 0x2000) {
    if(settings.mirror == 0) addr = ((addr & 0x0800) >> 1) | (addr & 0x03ff);
    return ppu.ciram_read(addr & 0x07ff);
  }
  addr = (chr_bank * 0x2000) + (addr & 0x1fff);
  return Board::chr_read(addr);
}

void chr_write(unsigned addr, uint8 data) {
  if(addr & 0x2000) {
    if(settings.mirror == 0) addr = ((addr & 0x0800) >> 1) | (addr & 0x03ff);
    return ppu.ciram_write(addr & 0x07ff, data);
  }
  addr = (chr_bank * 0x2000) + (addr & 0x1fff);
  Board::chr_write(addr, data);
}

void power() {
}

void reset() {
  prg_bank = 0;
  chr_bank = 0;
}

void serialize(serializer& s) {
  Board::serialize(s);
  s.integer(prg_bank);
  s.integer(chr_bank);
}

NES_GxROM(Markup::Node& document) : Board(document) {
  settings.mirror = document["cartridge/mirror/mode"].text() == "vertical" ? 1 : 0;
}

};