mirror of https://github.com/bsnes-emu/bsnes.git
56 lines
1.2 KiB
C++
Executable File
56 lines
1.2 KiB
C++
Executable File
#ifdef CARTRIDGE_CPP
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uint8 Cartridge::MBC2::mmio_read(uint16 addr) {
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if(addr >= 0x0000 && addr <= 0x3fff) {
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return cartridge.rom_read(addr);
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}
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if(addr >= 0x4000 && addr <= 0x7fff) {
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return cartridge.rom_read((rom_select << 14) | (addr & 0x3fff));
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}
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if(addr >= 0xa000 && addr <= 0xa1ff) {
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if(ram_enable) {
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uint8 data = cartridge.ram_read(addr & 0x1ff);
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return (addr & 1) == 0 ? ((data >> 4) & 0x0f) : ((data >> 0) & 0x0f);
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}
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return 0x00;
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}
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return 0x00;
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}
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void Cartridge::MBC2::mmio_write(uint16 addr, uint8 data) {
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if(addr >= 0x0000 && addr <= 0x1fff) {
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if((addr & 0x100) == 0) {
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ram_enable = (data & 0x0f) == 0x0a;
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}
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}
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if(addr >= 0x2000 && addr <= 0x3fff) {
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if(addr & 0x100) {
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rom_select = data & 0x0f;
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if(rom_select == 0) rom_select = 1;
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}
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}
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if(addr >= 0xa000 && addr <= 0xa1ff) {
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if(ram_enable) {
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addr &= 511;
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if((addr & 1) == 0) {
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cartridge.ram_write(addr, (cartridge.ram_read(addr) & 0x0f) | (data << 4));
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} else {
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cartridge.ram_write(addr, (cartridge.ram_read(addr) & 0xf0) | (data << 0));
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}
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return;
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}
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}
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}
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void Cartridge::MBC2::power() {
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ram_enable = false;
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rom_select = 0x01;
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}
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#endif
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