mirror of https://github.com/bsnes-emu/bsnes.git
67 lines
1.5 KiB
C++
67 lines
1.5 KiB
C++
auto Cartridge::MBC1::mmio_read(uint16 addr) -> uint8 {
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if((addr & 0xc000) == 0x0000) { //$0000-3fff
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return cartridge.rom_read(addr);
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}
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if((addr & 0xc000) == 0x4000) { //$4000-7fff
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if(mode_select == 0) {
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return cartridge.rom_read((ram_select << 19) | (rom_select << 14) | (addr & 0x3fff));
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} else {
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return cartridge.rom_read((rom_select << 14) | (addr & 0x3fff));
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}
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}
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if((addr & 0xe000) == 0xa000) { //$a000-bfff
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if(ram_enable) {
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if(mode_select == 0) {
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return cartridge.ram_read(addr & 0x1fff);
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} else {
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return cartridge.ram_read((ram_select << 13) | (addr & 0x1fff));
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}
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}
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return 0xff;
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}
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return 0xff;
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}
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auto Cartridge::MBC1::mmio_write(uint16 addr, uint8 data) -> void {
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if((addr & 0xe000) == 0x0000) { //$0000-1fff
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ram_enable = (data & 0x0f) == 0x0a;
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return;
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}
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if((addr & 0xe000) == 0x2000) { //$2000-3fff
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rom_select = (data & 0x1f) + ((data & 0x1f) == 0);
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return;
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}
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if((addr & 0xe000) == 0x4000) { //$4000-5fff
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ram_select = data & 0x03;
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return;
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}
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if((addr & 0xe000) == 0x6000) { //$6000-7fff
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mode_select = data & 0x01;
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return;
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}
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if((addr & 0xe000) == 0xa000) { //$a000-bfff
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if(ram_enable) {
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if(mode_select == 0) {
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cartridge.ram_write(addr & 0x1fff, data);
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} else {
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cartridge.ram_write((ram_select << 13) | (addr & 0x1fff), data);
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}
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}
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return;
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}
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}
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auto Cartridge::MBC1::power() -> void {
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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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mode_select = 0;
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}
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