struct SuperFamicomCartridge { SuperFamicomCartridge(const uint8_t* data, uint size, bool has_msu1 = false); string markup; //private: auto readHeader(const uint8_t* data, uint size) -> void; auto findHeader(const uint8_t* data, uint size) -> uint; auto scoreHeader(const uint8_t* data, uint size, uint addr) -> uint; enum HeaderField : uint { CartName = 0x00, Mapper = 0x15, RomType = 0x16, RomSize = 0x17, RamSize = 0x18, CartRegion = 0x19, Company = 0x1a, Version = 0x1b, Complement = 0x1c, //inverse checksum Checksum = 0x1e, ResetVector = 0x3c, }; enum class Type : uint { SatellaviewBIOS, SufamiTurboBIOS, SuperGameBoy1BIOS, SuperGameBoy2BIOS, LoROM, HiROM, ExLoROM, ExHiROM, SuperFX, SA1, LoROMSatellaview, HiROMSatellaview, CampusChallenge92, Powerfest94, //invalid types Unknown, GameBoy, Satellaview, SufamiTurbo, }; enum class Region : uint { NTSC, PAL, }; enum class DSP1Type : uint { None, LoROM1MB, LoROM2MB, HiROM, }; bool loaded = false; //is a base cartridge inserted? uint crc32 = 0; //crc32 of all cartridges (base+slot(s)) uint rom_size = 0; uint ram_size = 0; bool firmware_required = false; //true if firmware is required for emulation bool firmware_appended = false; //true if firmware is present at end of data Type type = Type::Unknown; Region region = Region::NTSC; DSP1Type dsp1_type = DSP1Type::None; bool has_bsx_slot = false; bool has_superfx = false; bool has_sa1 = false; bool has_sharprtc = false; bool has_epsonrtc = false; bool has_sdd1 = false; bool has_spc7110 = false; bool has_cx4 = false; bool has_dsp1 = false; bool has_dsp2 = false; bool has_dsp3 = false; bool has_dsp4 = false; bool has_obc1 = false; bool has_st010 = false; bool has_st011 = false; bool has_st018 = false; }; SuperFamicomCartridge::SuperFamicomCartridge(const uint8_t* data, uint size, bool has_msu1) { //skip copier header if((size & 0x7fff) == 512) data += 512, size -= 512; if(size < 0x8000) return; readHeader(data, size); if(type == Type::Unknown) return; if(type == Type::GameBoy) return; if(type == Type::Satellaview) return; if(type == Type::SufamiTurbo) return; const char* range = (rom_size > 0x200000) || (ram_size > 32 * 1024) ? "0000-7fff" : "0000-ffff"; markup.append("board region=", region == Region::NTSC ? "ntsc" : "pal", "\n"); //detect appended firmware if(has_dsp1) { firmware_required = true; if((size & 0x7fff) == 0x2000) { firmware_appended = true; rom_size -= 0x2000; } } if(has_dsp2) { firmware_required = true; if((size & 0x7fff) == 0x2000) { firmware_appended = true; rom_size -= 0x2000; } } if(has_dsp3) { firmware_required = true; if((size & 0x7fff) == 0x2000) { firmware_appended = true; rom_size -= 0x2000; } } if(has_dsp4) { firmware_required = true; if((size & 0x7fff) == 0x2000) { firmware_appended = true; rom_size -= 0x2000; } } if(has_st010) { firmware_required = true; if((size & 0xffff) == 0xd000) { firmware_appended = true; rom_size -= 0xd000; } } if(has_st011) { firmware_required = true; if((size & 0xffff) == 0xd000) { firmware_appended = true; rom_size -= 0xd000; } } if(has_st018) { firmware_required = true; if((size & 0x3ffff) == 0x28000) { firmware_appended = true; rom_size -= 0x28000; } } if(has_cx4) { firmware_required = true; if((rom_size & 0x7fff) == 0xc00) { firmware_appended = true; rom_size -= 0xc00; } } if(type == Type::SuperGameBoy1BIOS || type == Type::SuperGameBoy2BIOS) { firmware_required = true; if((rom_size & 0x7fff) == 0x100) { firmware_appended = true; rom_size -= 0x100; } } //end firmware detection if(type == Type::SatellaviewBIOS) { markup.append( " ram name=save.ram size=0x", hex(ram_size), "\n" " map address=10-1f:5000-5fff mask=0xf000\n" " mcc\n" " map address=00-0f:5000\n" " map=mcu address=00-3f,80-bf:8000-ffff mask=0x408000\n" " map=mcu address=40-7d,c0-ff:0000-ffff\n" " rom name=program.rom size=0x", hex(rom_size), "\n" " ram name=download.ram size=0x80000\n" " map address=00-3f,80-bf:6000-7fff mask=0xe000\n" " bsmemory\n" ); } else if(type == Type::SufamiTurboBIOS) { markup.append( " rom name=program.rom size=0x", hex(rom_size), "\n" " map address=00-1f,80-9f:8000-ffff mask=0x8000\n" " sufamiturbo\n" " rom\n" " map address=20-3f,a0-bf:8000-ffff mask=0x8000\n" " ram\n" " map address=60-6f,e0-ef:0000-ffff\n" " sufamiturbo\n" " rom\n" " map address=40-5f,c0-df:0000-7fff mask=0x8000\n" " map address=40-5f,c0-df:8000-ffff mask=0x8000\n" " ram\n" " map address=70-7d,f0-ff:0000-ffff\n" ); } else if(type == Type::SuperGameBoy1BIOS || type == Type::SuperGameBoy2BIOS) { markup.append( " rom name=program.rom size=0x", hex(rom_size), "\n" " map address=00-7d,80-ff:8000-ffff mask=0x8000\n" " map address=40-7d,c0-ff:0000-7fff mask=0x8000\n" " icd2 revision=1\n" " map address=00-3f,80-bf:6000-67ff,7000-7fff\n" " rom name=sgb.boot.rom size=0x100\n" ); } else if(has_cx4) { markup.append( " hitachidsp model=HG51B169 frequency=20000000\n" " map address=00-3f,80-bf:6c00-6fff,7c00-7fff\n" " rom name=program.rom size=0x", hex(rom_size), "\n" " map address=00-3f,80-bf:8000-ffff mask=0x8000\n" " ram name=save.ram size=0\n" " map address=70-77:0000-7fff mask=0x8000\n" " drom name=cx4.data.rom size=0xc00\n" " dram name=cx4.data.ram size=0xc00 volatile\n" " map address=00-3f,80-bf:6000-6bff,7000-7bff mask=0xf000\n" ); } else if(has_spc7110) { markup.append( " spc7110\n" " map address=00-3f,80-bf:4800-483f\n" " map address=50,58:0000-ffff\n" " map=mcu address=00-3f,80-bf:8000-ffff mask=0x800000\n" " map=mcu address=c0-ff:0000-ffff mask=0xc00000\n" " prom name=program.rom size=0x100000\n" " drom name=data.rom size=0x", hex(rom_size - 0x100000), "\n" " ram name=save.ram size=0x", hex(ram_size), "\n" " map address=00-3f,80-bf:6000-7fff mask=0xe000\n" ); } else if(has_sdd1) { markup.append( " sdd1\n" " map address=00-3f,80-bf:4800-480f\n" " rom name=program.rom size=0x", hex(rom_size), "\n" " map address=00-3f,80-bf:8000-ffff\n" " map address=c0-ff:0000-ffff\n" ); if(ram_size > 0) markup.append( " ram name=save.ram size=0x", hex(ram_size), "\n" " map address=00-3f,80-bf:6000-7fff mask=0xe000\n" " map address=70-73:0000-ffff mask=0x8000\n" ); } else if(type == Type::LoROM) { markup.append( " rom name=program.rom size=0x", hex(rom_size), "\n" " map address=00-7d,80-ff:8000-ffff mask=0x8000\n" " map address=40-6f,c0-ef:0000-7fff mask=0x8000\n" ); if(ram_size > 0) markup.append( " ram name=save.ram size=0x", hex(ram_size), "\n" " map address=70-7d,f0-ff:", range, "\n" ); } else if(type == Type::HiROM) { markup.append( " rom name=program.rom size=0x", hex(rom_size), "\n" " map address=00-3f,80-bf:8000-ffff\n" " map address=40-7f,c0-ff:0000-ffff\n" ); if(ram_size > 0) markup.append( " ram name=save.ram size=0x", hex(ram_size), "\n" " map address=10-3f,90-bf:6000-7fff mask=0xe000\n" ); } else if(type == Type::ExLoROM) { markup.append( " rom name=program.rom size=0x", hex(rom_size), "\n" " map address=00-3f,80-bf:8000-ffff mask=0x8000\n" " map address=40-7d:0000-ffff\n" ); if(ram_size > 0) markup.append( " ram name=save.ram size=0x", hex(ram_size), "\n" " map address=20-3f,a0-bf:6000-7fff mask=0xe000\n" " map address=70-7d:0000-7fff mask=0x8000\n" ); } else if(type == Type::ExHiROM) { markup.append( " rom name=program.rom size=0x", hex(rom_size), "\n" " map address=00-3f:8000-ffff base=0x400000\n" " map address=40-7d:0000-ffff base=0x400000\n" " map address=80-bf:8000-ffff mask=0xc00000\n" " map address=c0-ff:0000-ffff mask=0xc00000\n" ); if(ram_size > 0) markup.append( " ram name=save.ram size=0x", hex(ram_size), "\n" " map address=20-3f,a0-bf:6000-7fff mask=0xe000\n" " map address=70-7d:", range, "\n" ); } else if(type == Type::SuperFX) { markup.append( " superfx\n" " map address=00-3f,80-bf:3000-34ff\n" " rom name=program.rom size=0x", hex(rom_size), "\n" " map address=00-3f,80-bf:8000-ffff mask=0x8000\n" " map address=40-5f,c0-df:0000-ffff\n" ); if(ram_size > 0) markup.append( " ram name=save.ram size=0x", hex(ram_size), "\n" " map address=00-3f,80-bf:6000-7fff size=0x2000\n" " map address=70-71,f0-f1:0000-ffff\n" ); } else if(type == Type::SA1) { markup.append( " sa1\n" " map address=00-3f,80-bf:2200-23ff\n" " rom name=program.rom size=0x", hex(rom_size), "\n" " map address=00-3f,80-bf:8000-ffff mask=0x408000\n" " map address=c0-ff:0000-ffff\n" ); if(ram_size > 0) markup.append( " bwram name=save.ram size=0x", hex(ram_size), "\n" " map address=00-3f,80-bf:6000-7fff size=0x2000\n" " map address=40-4f:0000-ffff\n" ); markup.append( " iram id=internal size=0x800 volatile\n" " map address=00-3f,80-bf:3000-37ff size=0x800\n" ); } else if(type == Type::LoROMSatellaview) { markup.append( " rom name=program.rom size=0x", hex(rom_size), "\n" " map address=00-1f:8000-ffff base=0x000000 mask=0x8000\n" " map address=20-3f:8000-ffff base=0x100000 mask=0x8000\n" " map address=80-9f:8000-ffff base=0x200000 mask=0x8000\n" " map address=a0-bf:8000-ffff base=0x100000 mask=0x8000\n" " ram name=save.ram size=0x", hex(ram_size), "\n" " map address=70-7d,f0-ff:0000-7fff mask=0x8000\n" " bsmemory\n" " map address=c0-ef:0000-ffff\n" ); } else if(type == Type::HiROMSatellaview) { markup.append( " rom name=program.rom size=0x", hex(rom_size), "\n" " map address=00-1f,80-9f:8000-ffff\n" " map address=40-5f,c0-df:0000-ffff\n" " ram name=save.ram size=0x", hex(ram_size), "\n" " map address=20-3f,a0-bf:6000-7fff\n" " bsmemory\n" " map address=20-3f,a0-bf:8000-ffff\n" " map address=60-7f,e0-ff:0000-ffff\n" ); } else if(type == Type::CampusChallenge92) { markup.append( " event=CC92 timer=360\n" " map address=c0,e0:0000\n" " map=mcu address=00-1f,80-9f:8000-ffff\n" " rom name=program.rom size=0x40000\n" " rom name=slot-1.rom size=0x80000\n" " rom name=slot-2.rom size=0x80000\n" " rom name=slot-3.rom size=0x80000\n" " ram name=save.ram size=0x2000 volatile\n" " map address=70-7d,f0-ff:0000-7fff mask=0x8000\n" " necdsp model=uPD7725 frequency=8000000\n" " map address=20-3f,a0-bf:8000-ffff mask=0x7fff\n" " prom name=dsp1.program.rom size=0x1800\n" " drom name=dsp1.data.rom size=0x800\n" " dram name=dsp1.data.ram size=0x200 volatile\n" ); return; } else if(type == Type::Powerfest94) { markup.append( " event=PF94 timer=360\n" " map address=10,20:6000\n" " map=mcu address=00-3f,80-bf:8000-ffff\n" " map=mcu address=c0-ff:0000-ffff\n" " rom name=program.rom size=0x40000\n" " rom name=slot-1.rom size=0x80000\n" " rom name=slot-2.rom size=0x80000\n" " rom name=slot-3.rom size=0x100000\n" " ram name=save.ram size=0x2000 volatile\n" " map address=30-3f,b0-bf:6000-7fff mask=0xe000\n" " necdsp model=uPD7725 frequency=8000000\n" " map address=00-0f,80-8f:6000-7fff mask=0xfff\n" " prom name=dsp1.program.rom size=0x1800\n" " drom name=dsp1.data.rom size=0x800\n" " dram name=dsp1.data.ram size=0x200 volatile\n" ); return; } if(has_sharprtc) { markup.append( " sharprtc\n" " map address=00-3f,80-bf:2800-2801\n" " ram name=rtc.ram size=0x10\n" ); } if(has_epsonrtc) { markup.append( " epsonrtc\n" " map address=00-3f,80-bf:4840-4842\n" " ram name=rtc.ram size=0x10\n" ); } if(has_obc1) { markup.append( " obc1\n" " map address=00-3f,80-bf:6000-7fff mask=0xe000\n" " ram name=save.ram size=0x2000\n" ); } if(has_dsp1) { markup.append( " necdsp model=uPD7725 frequency=8000000\n" ); if(dsp1_type == DSP1Type::LoROM1MB) markup.append( " map address=20-3f,a0-bf:8000-ffff mask=0x3fff\n" ); if(dsp1_type == DSP1Type::LoROM2MB) markup.append( " map address=60-6f,e0-ef:0000-7fff mask=0x3fff\n" ); if(dsp1_type == DSP1Type::HiROM) markup.append( " map address=00-1f,80-9f:6000-7fff mask=0xfff\n" ); markup.append( " prom name=dsp1b.program.rom size=0x1800\n" " drom name=dsp1b.data.rom size=0x800\n" " dram name=dsp1b.data.ram size=0x200 volatile\n" ); } if(has_dsp2) { markup.append( " necdsp model=uPD7725 frequency=8000000\n" " map address=20-3f,a0-bf:8000-ffff mask=0x3fff\n" " prom name=dsp2.program.rom size=0x1800\n" " drom name=dsp2.data.rom size=0x800\n" " dram name=dsp2.data.ram size=0x200 volatile\n" ); } if(has_dsp3) { markup.append( " necdsp model=uPD7725 frequency=8000000\n" " map address=20-3f,a0-bf:8000-ffff mask=0x3fff\n" " prom name=dsp3.program.rom size=0x1800\n" " drom name=dsp3.data.rom size=0x800\n" " dram name=dsp3.data.ram size=0x200 volatile\n" ); } if(has_dsp4) { markup.append( " necdsp model=uPD7725 frequency=8000000\n" " map address=30-3f,b0-bf:8000-ffff mask=0x3fff\n" " prom name=dsp4.program.rom size=0x1800\n" " drom name=dsp4.data.rom size=0x800\n" " dram name=dsp4.data.ram size=0x200 volatile\n" ); } if(has_st010) { markup.append( " necdsp model=uPD96050 frequency=11000000\n" " map address=60-67,e0-e7:0000-3fff\n" " prom name=st010.program.rom size=0xc000\n" " drom name=st010.data.rom size=0x1000\n" " dram name=save.ram size=0x1000\n" " map address=68-6f,e8-ef:0000-7fff mask=0x8000\n" ); } if(has_st011) { markup.append( " necdsp model=uPD96050 frequency=15000000\n" " map address=60-67,e0-e7:0000-3fff\n" " prom name=st011.program.rom size=0xc000\n" " drom name=st011.data.rom size=0x1000\n" " dram name=save.ram size=0x1000\n" " map address=68-6f,e8-ef:0000-7fff mask=0x8000\n" ); } if(has_st018) { markup.append( " armdsp frequency=21477272\n" " map address=00-3f,80-bf:3800-38ff\n" " prom name=st018.program.rom size=0x20000\n" " drom name=st018.data.rom size=0x8000\n" " ram name=save.ram size=0x4000\n" ); } if(has_msu1) { markup.append( " msu1\n" " map address=00-3f,80-bf:2000-2007\n" " rom name=msu1.rom\n" ); } } auto SuperFamicomCartridge::readHeader(const uint8_t* data, uint size) -> void { //detect Game Boy carts if(size >= 0x0140) { if(data[0x0104] == 0xce && data[0x0105] == 0xed && data[0x0106] == 0x66 && data[0x0107] == 0x66 && data[0x0108] == 0xcc && data[0x0109] == 0x0d && data[0x010a] == 0x00 && data[0x010b] == 0x0b) { type = Type::GameBoy; return; } } const uint index = findHeader(data, size); const uint8_t mapperid = data[index + Mapper]; const uint8_t rom_type = data[index + RomType]; const uint8_t rom_size = data[index + RomSize]; const uint8_t company = data[index + Company]; const uint8_t regionid = data[index + CartRegion] & 0x7f; const uint16_t complement = data[index + Complement] | data[index + Complement + 1] << 8; const uint16_t checksum = data[index + Checksum] | data[index + Checksum + 1] << 8; this->rom_size = size; ram_size = 1024 << (data[index + RamSize] & 7); if(ram_size == 1024) ram_size = 0; //no RAM present if(rom_size == 0 && ram_size) ram_size = 0; //fix for Bazooka Blitzkrieg's malformed header (swapped ROM and RAM sizes) //0, 1, 13 = NTSC; 2 - 12 = PAL region = (regionid <= 1 || regionid >= 13) ? Region::NTSC : Region::PAL; //detect BS-X flash carts if(data[index + 0x13] == 0x00 || data[index + 0x13] == 0xff) { if(data[index + 0x14] == 0x00) { const uint8_t n15 = data[index + 0x15]; if(n15 == 0x00 || n15 == 0x80 || n15 == 0x84 || n15 == 0x9c || n15 == 0xbc || n15 == 0xfc) { if(data[index + 0x1a] == 0x33 || data[index + 0x1a] == 0xff) { type = Type::Satellaview; region = Region::NTSC; //BS-X only released in Japan return; } } } } //detect Sufami Turbo carts if(!memcmp(data, "BANDAI SFC-ADX", 14)) { if(!memcmp(data + 16, "SFC-ADX BACKUP", 14)) { type = Type::SufamiTurboBIOS; } else { type = Type::SufamiTurbo; } region = Region::NTSC; //Sufami Turbo only released in Japan return; //RAM size handled outside this routine } //detect Super Game Boy BIOS if(!memcmp(data + index, "Super GAMEBOY2", 14)) { type = Type::SuperGameBoy2BIOS; return; } if(!memcmp(data + index, "Super GAMEBOY", 13)) { type = Type::SuperGameBoy1BIOS; return; } //detect competition carts if(!memcmp(data + index, "\x00\x08\x22\x02\x1c\x00\x10\x00\x08\x65\x80\x84\x20\x00\x22\x25\x00\x83\x0c\x80\x10", 21) && complement == 0x0100 && checksum == 0x2d02 && (size == 0x1c0000 || size == 0x1c2000)) { type = Type::CampusChallenge92; //dark title screen version return; } if(!memcmp(data + index, "\xc9\x80\x80\x44\x15\x00\x62\x09\x29\xa0\x52\x70\x50\x12\x05\x35\x31\x63\xc0\x22\x01", 21) && complement == 0x2011 && checksum == 0xf8c0 && (size == 0x240000 || size == 0x242000)) { type = Type::Powerfest94; //10,000 points version return; } if(!memcmp(data + index, "PREHISTORIK MAN ", 21) && complement == 0xffff && checksum == 0x0000 && (size == 0x240000 || size == 0x242000)) { type = Type::Powerfest94; //1,000,000 points version return; } //detect presence of BS-X flash cartridge connector (reads extended header information) if(data[index - 14] == 'Z') { if(data[index - 11] == 'J') { uint8_t n13 = data[index - 13]; if((n13 >= 'A' && n13 <= 'Z') || (n13 >= '0' && n13 <= '9')) { if(company == 0x33 || (data[index - 10] == 0x00 && data[index - 4] == 0x00)) { has_bsx_slot = true; } } } } if(has_bsx_slot) { if(!memcmp(data + index, "Satellaview BS-X ", 21)) { //BS-X base cart type = Type::SatellaviewBIOS; region = Region::NTSC; //BS-X only released in Japan return; //RAM size handled internally by load_cart_bsx() -> BSXCart class } else { type = (index == 0x7fc0 ? Type::LoROMSatellaview : Type::HiROMSatellaview); region = Region::NTSC; //BS-X slotted cartridges only released in Japan } } else { //standard cart if(index == 0x7fc0 && size >= 0x401000) { type = Type::ExLoROM; } else if(index == 0x7fc0 && mapperid == 0x32) { type = Type::ExLoROM; } else if(index == 0x7fc0) { type = Type::LoROM; } else if(index == 0xffc0) { type = Type::HiROM; } else if(index == 0x40ffc0) { type = Type::ExHiROM; } else { type = Type::Unknown; return; } } if(mapperid == 0x20 && (rom_type == 0x13 || rom_type == 0x14 || rom_type == 0x15 || rom_type == 0x1a)) { has_superfx = true; type = Type::SuperFX; ram_size = 1024 << (data[index - 3] & 7); if(ram_size == 1024) ram_size = 0; } if(mapperid == 0x23 && (rom_type == 0x32 || rom_type == 0x34 || rom_type == 0x35)) { has_sa1 = true; type = Type::SA1; } if(mapperid == 0x35 && rom_type == 0x55) { has_sharprtc = true; } if(mapperid == 0x32 && (rom_type == 0x43 || rom_type == 0x45)) { has_sdd1 = true; } if(mapperid == 0x3a && (rom_type == 0xf5 || rom_type == 0xf9)) { has_spc7110 = true; has_epsonrtc = (rom_type == 0xf9); } if(mapperid == 0x20 && rom_type == 0xf3) { has_cx4 = true; } if((mapperid == 0x20 || mapperid == 0x21) && rom_type == 0x03) { has_dsp1 = true; } if(mapperid == 0x30 && rom_type == 0x05 && company != 0xb2) { has_dsp1 = true; } if(mapperid == 0x31 && (rom_type == 0x03 || rom_type == 0x05)) { has_dsp1 = true; } if(has_dsp1 == true) { if((mapperid & 0x2f) == 0x20 && size <= 0x100000) { dsp1_type = DSP1Type::LoROM1MB; } else if((mapperid & 0x2f) == 0x20) { dsp1_type = DSP1Type::LoROM2MB; } else if((mapperid & 0x2f) == 0x21) { dsp1_type = DSP1Type::HiROM; } } if(mapperid == 0x20 && rom_type == 0x05) { has_dsp2 = true; } if(mapperid == 0x30 && rom_type == 0x05 && company == 0xb2) { has_dsp3 = true; } if(mapperid == 0x30 && rom_type == 0x03) { has_dsp4 = true; } if(mapperid == 0x30 && rom_type == 0x25) { has_obc1 = true; } if(mapperid == 0x30 && rom_type == 0xf6 && rom_size >= 10) { has_st010 = true; } if(mapperid == 0x30 && rom_type == 0xf6 && rom_size < 10) { has_st011 = true; } if(mapperid == 0x30 && rom_type == 0xf5) { has_st018 = true; } } auto SuperFamicomCartridge::findHeader(const uint8_t* data, uint size) -> uint { uint score_lo = scoreHeader(data, size, 0x007fc0); uint score_hi = scoreHeader(data, size, 0x00ffc0); uint score_ex = scoreHeader(data, size, 0x40ffc0); if(score_ex) score_ex += 4; //favor ExHiROM on images > 32mbits if(score_lo >= score_hi && score_lo >= score_ex) { return 0x007fc0; } else if(score_hi >= score_ex) { return 0x00ffc0; } else { return 0x40ffc0; } } auto SuperFamicomCartridge::scoreHeader(const uint8_t* data, uint size, uint addr) -> uint { if(size < addr + 64) return 0; //image too small to contain header at this location? int score = 0; uint16_t resetvector = data[addr + ResetVector] | (data[addr + ResetVector + 1] << 8); uint16_t checksum = data[addr + Checksum ] | (data[addr + Checksum + 1] << 8); uint16_t complement = data[addr + Complement ] | (data[addr + Complement + 1] << 8); uint8_t resetop = data[(addr & ~0x7fff) | (resetvector & 0x7fff)]; //first opcode executed upon reset uint8_t mapper = data[addr + Mapper] & ~0x10; //mask off irrelevent FastROM-capable bit //$00:[000-7fff] contains uninitialized RAM and MMIO. //reset vector must point to ROM at $00:[8000-ffff] to be considered valid. if(resetvector < 0x8000) return 0; //some images duplicate the header in multiple locations, and others have completely //invalid header information that cannot be relied upon. //below code will analyze the first opcode executed at the specified reset vector to //determine the probability that this is the correct header. //most likely opcodes if(resetop == 0x78 //sei || resetop == 0x18 //clc (clc; xce) || resetop == 0x38 //sec (sec; xce) || resetop == 0x9c //stz $nnnn (stz $4200) || resetop == 0x4c //jmp $nnnn || resetop == 0x5c //jml $nnnnnn ) score += 8; //plausible opcodes if(resetop == 0xc2 //rep #$nn || resetop == 0xe2 //sep #$nn || resetop == 0xad //lda $nnnn || resetop == 0xae //ldx $nnnn || resetop == 0xac //ldy $nnnn || resetop == 0xaf //lda $nnnnnn || resetop == 0xa9 //lda #$nn || resetop == 0xa2 //ldx #$nn || resetop == 0xa0 //ldy #$nn || resetop == 0x20 //jsr $nnnn || resetop == 0x22 //jsl $nnnnnn ) score += 4; //implausible opcodes if(resetop == 0x40 //rti || resetop == 0x60 //rts || resetop == 0x6b //rtl || resetop == 0xcd //cmp $nnnn || resetop == 0xec //cpx $nnnn || resetop == 0xcc //cpy $nnnn ) score -= 4; //least likely opcodes if(resetop == 0x00 //brk #$nn || resetop == 0x02 //cop #$nn || resetop == 0xdb //stp || resetop == 0x42 //wdm || resetop == 0xff //sbc $nnnnnn,x ) score -= 8; //at times, both the header and reset vector's first opcode will match ... //fallback and rely on info validity in these cases to determine more likely header. //a valid checksum is the biggest indicator of a valid header. if((checksum + complement) == 0xffff && (checksum != 0) && (complement != 0)) score += 4; if(addr == 0x007fc0 && mapper == 0x20) score += 2; //0x20 is usually LoROM if(addr == 0x00ffc0 && mapper == 0x21) score += 2; //0x21 is usually HiROM if(addr == 0x007fc0 && mapper == 0x22) score += 2; //0x22 is usually ExLoROM if(addr == 0x40ffc0 && mapper == 0x25) score += 2; //0x25 is usually ExHiROM if(data[addr + Company] == 0x33) score += 2; //0x33 indicates extended header if(data[addr + RomType] < 0x08) score++; if(data[addr + RomSize] < 0x10) score++; if(data[addr + RamSize] < 0x08) score++; if(data[addr + CartRegion] < 14) score++; if(score < 0) score = 0; return score; }