mirror of https://github.com/bsnes-emu/bsnes.git
62 lines
1.4 KiB
C++
62 lines
1.4 KiB
C++
auto Cartridge::MMM01::mmio_read(uint16 addr) -> uint8 {
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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 0xff;
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}
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return 0xff;
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}
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auto Cartridge::MMM01::mmio_write(uint16 addr, uint8 data) -> void {
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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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auto Cartridge::MMM01::power() -> void {
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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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