bsnes/higan/fc/cartridge/chip/vrc3.cpp

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struct VRC3 : Chip {
VRC3(Board& board) : Chip(board) {
}
auto main() -> void {
if(irqEnable) {
if(irqMode == 0) { //16-bit
if(++irqCounter.w == 0) {
irqLine = 1;
irqEnable = irqAcknowledge;
irqCounter.w = irqLatch;
}
}
if(irqMode == 1) { //8-bit
if(++irqCounter.l == 0) {
irqLine = 1;
irqEnable = irqAcknowledge;
irqCounter.l = irqLatch;
}
}
}
cpu.irqLine(irqLine);
tick();
}
auto addrPRG(uint addr) const -> uint {
uint bank = (addr < 0xc000 ? (uint)prgBank : 0x0f);
return (bank * 0x4000) + (addr & 0x3fff);
}
auto writeIO(uint addr, uint8 data) -> void {
switch(addr & 0xf000) {
case 0x8000: irqLatch = (irqLatch & 0xfff0) | ((data & 0x0f) << 0); break;
case 0x9000: irqLatch = (irqLatch & 0xff0f) | ((data & 0x0f) << 4); break;
case 0xa000: irqLatch = (irqLatch & 0xf0ff) | ((data & 0x0f) << 8); break;
case 0xb000: irqLatch = (irqLatch & 0x0fff) | ((data & 0x0f) << 12); break;
case 0xc000:
irqMode = data & 0x04;
irqEnable = data & 0x02;
irqAcknowledge = data & 0x01;
if(irqEnable) irqCounter.w = irqLatch;
break;
case 0xd000:
irqLine = 0;
irqEnable = irqAcknowledge;
break;
case 0xf000:
prgBank = data & 0x0f;
break;
}
}
auto power() -> void {
prgBank = 0;
irqMode = 0;
irqEnable = 0;
irqAcknowledge = 0;
irqLatch = 0;
irqCounter.w = 0;
irqLine = 0;
}
auto serialize(serializer& s) -> void {
s.integer(prgBank);
s.integer(irqMode);
s.integer(irqEnable);
s.integer(irqAcknowledge);
s.integer(irqLatch);
s.integer(irqCounter.w);
s.integer(irqLine);
}
uint4 prgBank;
bool irqMode;
bool irqEnable;
bool irqAcknowledge;
uint16 irqLatch;
struct {
union {
uint16_t w;
struct { uint8_t order_lsb2(l, h); };
};
} irqCounter;
bool irqLine;
};