arm7tdmi, gba: lock bus during SWP instruction

ares/component/processor/arm7tdmi/arm7tdmi.hpp

@@ -22,6 +22,8 @@ struct ARM7TDMI {
   virtual auto get(u32 mode, n32 address) -> n32 = 0;
   virtual auto getDebugger(u32 mode, n32 address) -> n32 { return get(mode, address); }
   virtual auto set(u32 mode, n32 address, n32 word) -> void = 0;
+  virtual auto lock() -> void { return; }
+  virtual auto unlock() -> void { return; }
 
   //arm7tdmi.cpp
   ARM7TDMI();

ares/component/processor/arm7tdmi/instructions-arm.cpp

@@ -131,9 +131,11 @@ auto ARM7TDMI::armInstructionLoadRegister
 
 auto ARM7TDMI::armInstructionMemorySwap
 (n4 m, n4 d, n4 n, n1 byte) -> void {
+  lock();
   n32 word = load((byte ? Byte : Word) | Nonsequential, r(n));
   store((byte ? Byte : Word) | Nonsequential, r(n), r(m));
   r(d) = word;
+  unlock();
 }
 
 auto ARM7TDMI::armInstructionMoveHalfImmediate

ares/gba/cpu/bus.cpp

@@ -80,6 +80,15 @@ auto CPU::set(u32 mode, n32 address, n32 word) -> void {
   openBus.set(mode, address, word);
 }
 
+auto CPU::lock() -> void {
+  dmaRun();
+  context.busLocked = true;
+}
+
+auto CPU::unlock() -> void {
+  context.busLocked = false;
+}
+
 auto CPU::_wait(u32 mode, n32 address) -> u32 {
   if(address >= 0x1000'0000) return 1;  //unmapped
   if(address <  0x0200'0000) return 1;

ares/gba/cpu/cpu.cpp

@@ -56,7 +56,7 @@ auto CPU::main() -> void {
 }
 
 auto CPU::dmaRun() -> void {
-  if(!context.dmaActive) {
+  if(!context.dmaActive && !context.busLocked) {
     context.dmaActive = true;
     while(dma[0].run() | dma[1].run() | dma[2].run() | dma[3].run());
     if(context.dmaRan) {

ares/gba/cpu/cpu.hpp

@@ -64,6 +64,8 @@ struct CPU : ARM7TDMI, Thread, IO {
   auto get(u32 mode, n32 address) -> n32 override;
   auto getDebugger(u32 mode, n32 address) -> n32 override;
   auto set(u32 mode, n32 address, n32 word) -> void override;
+  auto lock() -> void override;
+  auto unlock() -> void override;
   auto _wait(u32 mode, n32 address) -> u32;
 
   //io.cpp
@@ -255,6 +257,7 @@ struct CPU : ARM7TDMI, Thread, IO {
     n1  dmaRomAccess;
     n1  dmaActive;
     n1  timerLatched;
+    n1  busLocked;
   } context;
 };
 

ares/gba/cpu/serialization.cpp

@@ -117,4 +117,5 @@ auto CPU::serialize(serializer& s) -> void {
   s(context.dmaRomAccess);
   s(context.dmaActive);
   s(context.timerLatched);
+  s(context.busLocked);
 }

ares/gba/display/serialization.cpp

@@ -1,4 +1,6 @@
 auto Display::serialize(serializer& s) -> void {
+  Thread::serialize(s);
+
   s(io.vblank);
   s(io.hblank);
   s(io.vcoincidence);

ares/gba/system/serialization.cpp

@@ -1,4 +1,4 @@
-static const string SerializerVersion = "v141.4";
+static const string SerializerVersion = "v141.5";
 
 auto System::serialize(bool synchronize) -> serializer {
   if(synchronize) scheduler.enter(Scheduler::Mode::Synchronize);