ng: beginnings of neo geo cd emulation

This is just a basic skeleton that implements enough to boot the bios.

There is no CD-ROM support yet; games cannot boot.

ares/ng/apu/apu.cpp

@@ -9,7 +9,7 @@ APU apu;
 
 auto APU::load(Node::Object parent) -> void {
   node = parent->append<Node::Object>("APU");
-  ram.allocate(2_KiB);
+  ram.allocate(Model::NeoGeoCD() ? 64_KiB : 2_KiB);
   debugger.load(node);
 }
 
@@ -50,4 +50,13 @@ auto APU::power(bool reset) -> void {
   rom = {};
 }
 
+auto APU::restart() -> void {
+  Z80::reset();
+  Thread::restart({&APU::main, this});
+  communication = {};
+  nmi = {};
+  irq = {};
+  rom = {};
+}
+
 }

ares/ng/apu/apu.hpp

@@ -30,6 +30,7 @@ struct APU : Z80, Z80::Bus, Thread {
   auto main() -> void;
   auto step(u32 clocks) -> void override;
   auto power(bool reset) -> void;
+  auto restart() -> void;
 
   //memory.cpp
   auto read(n16 address) -> n8 override;

ares/ng/apu/memory.cpp

@@ -1,4 +1,5 @@
 auto APU::read(n16 address) -> n8 {
+  if(Model::NeoGeoCD()) return ram[address];
   if(address <= 0x7fff) return cartridge.readM(address);
   if(address <= 0xbfff) return cartridge.readM(rom.bankA << 14 | n14(address));
   if(address <= 0xdfff) return cartridge.readM(rom.bankB << 13 | n13(address));
@@ -9,6 +10,11 @@ auto APU::read(n16 address) -> n8 {
 }
 
 auto APU::write(n16 address, n8 data) -> void {
+  if(Model::NeoGeoCD()) {
+    ram[address] = data;
+    return;
+  }
+
   if(address >= 0xf800) {
     ram[address & 0x7ff] = data;
     return;

ares/ng/cpu/cpu.cpp

@@ -34,11 +34,13 @@ auto CPU::main() -> void {
 
     if(2 > r.i && lower(Interrupt::Timer)) {
       debugger.interrupt("Timer");
+      if(Model::NeoGeoCD()) return interrupt(Vector::Level1, 1);
       return interrupt(Vector::Level2, 2);
     }
 
     if(1 > r.i && lower(Interrupt::Vblank)) {
       debugger.interrupt("Vblank");
+      if(Model::NeoGeoCD()) return interrupt(Vector::Level2, 2);
       return interrupt(Vector::Level1, 1);
     }
   }