md: various i/o port improvements (#1341)

General fixes:
- model data lines separately from output data latches
- update data lines after control register writes
- distinguish between driven and floating data lines
- remove redundant data latch state from devices
- separate host input polling from data line synthesis

6 button/fighting pad fixes:
- reset timeout only on TH 0->1 transitions
- remain in last phase until timeout (don't wrap)
- read back C/B button state along with M/X/Y/Z

Mega mouse:
- remove erroneous thread synchronize on attach which could crash ares

Affected titles:
- Decap Attack (MD)
- Trouble Shooter/Battle Mania (MD)
- WWF Raw (32X)

ares/md/controller/control-pad/control-pad.cpp

@@ -11,9 +11,7 @@ ControlPad::ControlPad(Node::Port parent) {
   start = node->append<Node::Input::Button>("Start");
 }
 
-auto ControlPad::readData() -> n8 {
-  n6 data;
-
+auto ControlPad::poll() -> void {
   platform->input(up);
   platform->input(down);
   platform->input(left);
@@ -34,6 +32,10 @@ auto ControlPad::readData() -> n8 {
   } else if(!xHold) {
     xHold = 1, swap(leftLatch, rightLatch);
   }
+}
+
+auto ControlPad::readData() -> Data {
+  n6 data;
 
   if(select == 0) {
     data.bit(0) = upLatch;
@@ -51,10 +53,9 @@ auto ControlPad::readData() -> n8 {
   }
 
   data = ~data;
-  return latch << 7 | select << 6 | data;
+  return {data, 0x3f};
 }
 
 auto ControlPad::writeData(n8 data) -> void {
   select = data.bit(6);
-  latch = data.bit(7);
 }

ares/md/controller/control-pad/control-pad.hpp

@@ -10,12 +10,12 @@ struct ControlPad : Controller {
 
   ControlPad(Node::Port);
 
-  auto readData() -> n8 override;
+  auto poll() -> void override;
+  auto readData() -> Data override;
   auto writeData(n8 data) -> void override;
 
 private:
   n1 select = 1;
-  n1 latch;
 
   b1 yHold;
   b1 upLatch;

ares/md/controller/controller.hpp

@@ -17,9 +17,15 @@
 struct Controller {
   Node::Peripheral node;
 
+  struct Data {
+    n8 value;
+    n8 mask;
+  };
+
   virtual ~Controller() = default;
 
-  virtual auto readData() -> n8 { return 0xff; }
+  virtual auto poll() -> void {}
+  virtual auto readData() -> Data { return {0x7f, 0x7f}; }
   virtual auto writeData(n8 data) -> void {}
 };
 

ares/md/controller/fighting-pad/fighting-pad.cpp

@@ -23,15 +23,13 @@ FightingPad::~FightingPad() {
 
 auto FightingPad::main() -> void {
   if(timeout) {
-    timeout--;
-  } else {
-    counter = 0;
+    if(!--timeout) counter = 0;
   }
   Thread::step(1);
   Thread::synchronize(cpu);
 }
 
-auto FightingPad::readData() -> n8 {
+auto FightingPad::poll() -> void {
   platform->input(up);
   platform->input(down);
   platform->input(left);
@@ -56,7 +54,9 @@ auto FightingPad::readData() -> n8 {
   } else if(!xHold) {
     xHold = 1, swap(leftLatch, rightLatch);
   }
+}
 
+auto FightingPad::readData() -> Data {
   n6 data;
 
   if(select == 0) {
@@ -82,29 +82,28 @@ auto FightingPad::readData() -> n8 {
       data.bit(1) = downLatch;
       data.bit(2) = leftLatch;
       data.bit(3) = rightLatch;
-      data.bit(4) = b->value();
-      data.bit(5) = c->value();
     }
 
     if(counter == 3) {
       data.bit(0) = z->value();
       data.bit(1) = y->value();
       data.bit(2) = x->value();
       data.bit(3) = mode->value();
-      data.bit(4,5) = 0;
     }
+
+    data.bit(4) = b->value();
+    data.bit(5) = c->value();
   }
 
   data = ~data;
-  return latch << 7 | select << 6 | data;
+  return {data, 0x3f};
 }
 
 auto FightingPad::writeData(n8 data) -> void {
   if(!select && data.bit(6)) {  //0->1 transition
-    if(++counter == 5) counter = 0;
+    if(counter < 4) ++counter;
+    timeout = 1600;  //~1.6ms
   }
 
   select = data.bit(6);
-  latch = data.bit(7);
-  timeout = 1600;  //~1.6ms
 }

ares/md/controller/fighting-pad/fighting-pad.hpp

@@ -15,12 +15,12 @@ struct FightingPad : Controller, Thread {
   FightingPad(Node::Port);
   ~FightingPad();
   auto main() -> void;
-  auto readData() -> n8 override;
+  auto poll() -> void override;
+  auto readData() -> Data override;
   auto writeData(n8 data) -> void override;
 
 private:
   n1  select = 1;
-  n1  latch;
   n3  counter;
   n32 timeout;
 

ares/md/controller/mega-mouse/mega-mouse.cpp

@@ -38,7 +38,6 @@ MegaMouse::MegaMouse(Node::Port parent) {
   t_data = 10 * timerfreq / 1000000;
 
   Thread::create(timerfreq, {&MegaMouse::main, this});
-  Thread::synchronize(cpu);
 }
 
 MegaMouse::~MegaMouse() {
@@ -68,7 +67,7 @@ auto MegaMouse::main() -> void {
   Thread::synchronize(cpu);
 }
 
-auto MegaMouse::readData() -> n8 {
+auto MegaMouse::readData() -> Data {
   n8 data;
 
   if (th) {
@@ -81,14 +80,15 @@ auto MegaMouse::readData() -> n8 {
   }
 
   data.bit(4) = tl;
-  data.bit(5) = tr;
-  data.bit(6) = th;
-  data.bit(7) = latch;
 
-  return data;
+  return {data, 0x1f};
 }
 
 auto MegaMouse::writeData(n8 data) -> void {
+  //todo: this check wouldn't be necessary if the logic below was correct.
+  //this function should only respond to level changes.
+  if(tr == data.bit(5) && th == data.bit(6)) return;
+
   // Falling TH
   if (!data.bit(6) && th) {
     // When TH falls low, make sure the second nibble is driven. The
@@ -142,6 +142,5 @@ auto MegaMouse::writeData(n8 data) -> void {
      timeout = t_handshake;
   }
 
-  latch = data.bit(7);
   th = data.bit(6);
 }

ares/md/controller/mega-mouse/mega-mouse.hpp

@@ -10,14 +10,13 @@ struct MegaMouse : Controller, Thread {
   ~MegaMouse();
 
   auto main() -> void;
-  auto readData() -> n8 override;
+  auto readData() -> Data override;
   auto writeData(n8 data) -> void override;
 
 private:
   n1  th = 1;
   n1  tr = 1;
   n1  tl = 1;
-  n1  latch;
   n8  index = 0;
   n4  status[10];
   s16 maxspeed = 255;

ares/md/controller/port.cpp

@@ -29,10 +29,21 @@ auto ControllerPort::allocate(string name) -> Node::Peripheral {
   return {};
 }
 
+auto ControllerPort::update() -> void {
+  auto [inputData, inputMask] = device ? device->readData() : Controller::Data{0x7f, 0x7f};
+  n8 outputMask = 0x80 | control;
+  n8 prevLines = dataLines;
+  dataLines = inputData & inputMask | dataLines & ~inputMask;
+  dataLines = dataLatch & outputMask | dataLines & ~outputMask;
+  //todo: gradually pull up floating lines
+  if(device && prevLines != dataLines) return device->writeData(dataLines);
+}
+
 auto ControllerPort::power(bool reset) -> void {
   if(!reset) {
     control        = 0x00;
     dataLatch      = 0x7f;
+    dataLines      = 0x7f;
     serialControl  = 0x00;
     serialTxBuffer = 0xff;
     serialRxBuffer = 0x00;
@@ -42,6 +53,7 @@ auto ControllerPort::power(bool reset) -> void {
 auto ControllerPort::serialize(serializer& s) -> void {
   s(control);
   s(dataLatch);
+  s(dataLines);
   s(serialControl);
   s(serialTxBuffer);
   s(serialRxBuffer);

ares/md/controller/port.hpp

@@ -11,17 +11,17 @@ struct ControllerPort {
   auto connect(Node::Peripheral) -> void;
   auto disconnect() -> void { device.reset(); }
 
+  auto update() -> void;
+
   auto readControl() -> n8 { return control; }
-  auto writeControl(n8 data) -> void { control = data; }
+  auto writeControl(n8 data) -> void { control = data; update(); }
 
   auto readData() -> n8 {
-    n8 data = device ? device->readData() : n8(~0);
-    return dataLatch = dataLatch & (0x80 | control) | data & ~(0x80 | control);
-  }
-  auto writeData(n8 data) -> void {
-    dataLatch = dataLatch & ~(0x80 | control) | data & (0x80 | control);
-    if(device) return device->writeData(dataLatch);
+    if(device) device->poll();
+    update();
+    return dataLines;
   }
+  auto writeData(n8 data) -> void { dataLatch = data; update(); }
 
   // TODO: Implement working serial transfers. This code is mostly placeholder.
 
@@ -57,6 +57,7 @@ struct ControllerPort {
   const string name;
   n8 control;  //d0-d6 = PC0-PC6 (0 = input; 1 = output); d7 = TH-INT enable
   n8 dataLatch;
+  n8 dataLines;
   n8 serialControl;
   n8 serialTxBuffer;
   n8 serialRxBuffer;

ares/md/system/serialization.cpp

@@ -1,4 +1,4 @@
-static const string SerializerVersion = "v133.1";
+static const string SerializerVersion = "v134";
 
 auto System::serialize(bool synchronize) -> serializer {
   if(synchronize) scheduler.enter(Scheduler::Mode::Synchronize);