mirror of https://github.com/bsnes-emu/bsnes.git
68 lines
1.7 KiB
C++
68 lines
1.7 KiB
C++
auto Cartridge::MBC1::read(uint16 address) -> uint8 {
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if((address & 0xc000) == 0x0000) { //$0000-3fff
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return cartridge.rom.read(address.bits(0,13));
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}
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if((address & 0xc000) == 0x4000) { //$4000-7fff
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if(io.mode == 0) {
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return cartridge.rom.read(io.ram.bank << 19 | io.rom.bank << 14 | address.bits(0,13));
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} else {
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return cartridge.rom.read(io.rom.bank << 14 | address.bits(0,13));
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}
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}
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if((address & 0xe000) == 0xa000) { //$a000-bfff
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if(!io.ram.enable) return 0xff;
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if(io.mode == 0) {
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return cartridge.ram.read(address.bits(0,12));
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} else {
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return cartridge.ram.read(io.ram.bank << 13 | address.bits(0,12));
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}
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}
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return 0xff;
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}
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auto Cartridge::MBC1::write(uint16 address, uint8 data) -> void {
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if((address & 0xe000) == 0x0000) { //$0000-1fff
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io.ram.enable = data.bits(0,3) == 0x0a;
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return;
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}
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if((address & 0xe000) == 0x2000) { //$2000-3fff
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io.rom.bank = data.bits(0,4);
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if(!io.rom.bank) io.rom.bank = 0x01;
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return;
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}
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if((address & 0xe000) == 0x4000) { //$4000-5fff
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io.ram.bank = data.bits(0,1);
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return;
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}
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if((address & 0xe000) == 0x6000) { //$6000-7fff
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io.mode = data.bit(0);
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return;
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}
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if((address & 0xe000) == 0xa000) { //$a000-bfff
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if(!io.ram.enable) return;
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if(io.mode == 0) {
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return cartridge.ram.write(address.bits(0,12), data);
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} else {
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return cartridge.ram.write(io.ram.bank << 13 | address.bits(0,12), data);
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}
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}
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}
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auto Cartridge::MBC1::power() -> void {
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io = {};
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}
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auto Cartridge::MBC1::serialize(serializer& s) -> void {
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s.integer(io.mode);
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s.integer(io.rom.bank);
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s.integer(io.ram.enable);
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s.integer(io.ram.bank);
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}
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