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nes-gxrom.cpp
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nes-gxrom.cpp
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//NES-GNROM
//NES-MHROM
struct NES_GxROM : Board {
struct Settings {
bool mirror; //0 = horizontal, 1 = vertical
} settings;
uint2 prg_bank;
uint2 chr_bank;
uint8 prg_read(unsigned addr) {
if(addr & 0x8000) return prgrom.read((prg_bank << 15) | (addr & 0x7fff));
return cpu.mdr();
}
void prg_write(unsigned addr, uint8 data) {
if(addr & 0x8000) {
prg_bank = (data & 0x30) >> 4;
chr_bank = (data & 0x03) >> 0;
}
}
uint8 chr_read(unsigned addr) {
if(addr & 0x2000) {
if(settings.mirror == 0) addr = ((addr & 0x0800) >> 1) | (addr & 0x03ff);
return ppu.ciram_read(addr & 0x07ff);
}
addr = (chr_bank * 0x2000) + (addr & 0x1fff);
return Board::chr_read(addr);
}
void chr_write(unsigned addr, uint8 data) {
if(addr & 0x2000) {
if(settings.mirror == 0) addr = ((addr & 0x0800) >> 1) | (addr & 0x03ff);
return ppu.ciram_write(addr & 0x07ff, data);
}
addr = (chr_bank * 0x2000) + (addr & 0x1fff);
Board::chr_write(addr, data);
}
void power() {
}
void reset() {
prg_bank = 0;
chr_bank = 0;
}
void serialize(serializer& s) {
Board::serialize(s);
s.integer(prg_bank);
s.integer(chr_bank);
}
NES_GxROM(Markup::Node& document) : Board(document) {
settings.mirror = document["cartridge"]["mirror"]["mode"].data == "vertical" ? 1 : 0;
}
};