From 0109c27ad7c060ba3151c09e9746ae8822dcc6cd Mon Sep 17 00:00:00 2001
From: Jordan Woyak <jordan.woyak@gmail.com>
Date: Thu, 17 Apr 2025 03:33:54 -0500
Subject: [PATCH] SI: Fix GBA link by having a separate response for "error"
 and "no data".

---
 Source/Core/Core/HW/SI/SI.cpp                       | 13 ++++++++-----
 Source/Core/Core/HW/SI/SI_Device.h                  | 10 ++++++++--
 Source/Core/Core/HW/SI/SI_DeviceDanceMat.cpp        |  4 ++--
 Source/Core/Core/HW/SI/SI_DeviceDanceMat.h          |  2 +-
 Source/Core/Core/HW/SI/SI_DeviceGBA.cpp             |  4 ++--
 Source/Core/Core/HW/SI/SI_DeviceGBA.h               |  2 +-
 Source/Core/Core/HW/SI/SI_DeviceGBAEmu.cpp          |  4 ++--
 Source/Core/Core/HW/SI/SI_DeviceGBAEmu.h            |  2 +-
 Source/Core/Core/HW/SI/SI_DeviceGCAdapter.cpp       |  4 ++--
 Source/Core/Core/HW/SI/SI_DeviceGCAdapter.h         |  2 +-
 Source/Core/Core/HW/SI/SI_DeviceGCController.cpp    | 10 +++++-----
 Source/Core/Core/HW/SI/SI_DeviceGCController.h      |  5 ++---
 Source/Core/Core/HW/SI/SI_DeviceGCSteeringWheel.cpp |  4 ++--
 Source/Core/Core/HW/SI/SI_DeviceGCSteeringWheel.h   |  2 +-
 Source/Core/Core/HW/SI/SI_DeviceKeyboard.cpp        |  4 ++--
 Source/Core/Core/HW/SI/SI_DeviceKeyboard.h          |  3 +--
 Source/Core/Core/HW/SI/SI_DeviceNull.cpp            |  4 ++--
 Source/Core/Core/HW/SI/SI_DeviceNull.h              |  2 +-
 18 files changed, 44 insertions(+), 37 deletions(-)

diff --git a/Source/Core/Core/HW/SI/SI.cpp b/Source/Core/Core/HW/SI/SI.cpp
index 89b200bad4..350b0404c4 100644
--- a/Source/Core/Core/HW/SI/SI.cpp
+++ b/Source/Core/Core/HW/SI/SI.cpp
@@ -560,15 +560,18 @@ void SerialInterfaceManager::UpdateDevices()
   {
     // ERRLATCH bit is maintained.
     u32 errlatch = m_channel[i].in_hi.ERRLATCH.Value();
-    if (m_channel[i].device->GetData(m_channel[i].in_hi.hex, m_channel[i].in_lo.hex))
+    switch (m_channel[i].device->GetData(m_channel[i].in_hi.hex, m_channel[i].in_lo.hex))
     {
+    case DataResponse::Success:
       m_status_reg.hex |= GetRDSTBit(i);
-    }
-    else
-    {
+      break;
+    case DataResponse::ErrorNoResponse:
+      SetNoResponse(i);
+      [[fallthrough]];
+    case DataResponse::NoData:
       errlatch = 1;
       m_channel[i].in_hi.ERRSTAT = 1;
-      SetNoResponse(i);
+      break;
     }
 
     m_channel[i].in_hi.ERRLATCH = errlatch;
diff --git a/Source/Core/Core/HW/SI/SI_Device.h b/Source/Core/Core/HW/SI/SI_Device.h
index dbfce324ca..ebab7e3235 100644
--- a/Source/Core/Core/HW/SI/SI_Device.h
+++ b/Source/Core/Core/HW/SI/SI_Device.h
@@ -106,6 +106,13 @@ enum SIDevices : int
   SIDEVICE_COUNT,
 };
 
+enum class DataResponse
+{
+  NoData,
+  Success,
+  ErrorNoResponse,
+};
+
 class ISIDevice
 {
 public:
@@ -119,8 +126,7 @@ public:
   virtual int RunBuffer(u8* buffer, int request_length);
   virtual int TransferInterval();
 
-  // Return true on new data
-  virtual bool GetData(u32& hi, u32& low) = 0;
+  virtual DataResponse GetData(u32& hi, u32& low) = 0;
 
   // Send a command directly (no detour per buffer)
   virtual void SendCommand(u32 command, u8 poll) = 0;
diff --git a/Source/Core/Core/HW/SI/SI_DeviceDanceMat.cpp b/Source/Core/Core/HW/SI/SI_DeviceDanceMat.cpp
index cac1af0613..8dfb6f46b8 100644
--- a/Source/Core/Core/HW/SI/SI_DeviceDanceMat.cpp
+++ b/Source/Core/Core/HW/SI/SI_DeviceDanceMat.cpp
@@ -60,13 +60,13 @@ u32 CSIDevice_DanceMat::MapPadStatus(const GCPadStatus& pad_status)
   return (u32)(map << 16) | 0x8080;
 }
 
-bool CSIDevice_DanceMat::GetData(u32& hi, u32& low)
+DataResponse CSIDevice_DanceMat::GetData(u32& hi, u32& low)
 {
   CSIDevice_GCController::GetData(hi, low);
 
   // Identifies the dance mat
   low = 0x8080ffff;
 
-  return true;
+  return DataResponse::Success;
 }
 }  // namespace SerialInterface
diff --git a/Source/Core/Core/HW/SI/SI_DeviceDanceMat.h b/Source/Core/Core/HW/SI/SI_DeviceDanceMat.h
index c8743135a6..993420ef7d 100644
--- a/Source/Core/Core/HW/SI/SI_DeviceDanceMat.h
+++ b/Source/Core/Core/HW/SI/SI_DeviceDanceMat.h
@@ -17,6 +17,6 @@ public:
 
   int RunBuffer(u8* buffer, int request_length) override;
   u32 MapPadStatus(const GCPadStatus& pad_status) override;
-  bool GetData(u32& hi, u32& low) override;
+  DataResponse GetData(u32& hi, u32& low) override;
 };
 }  // namespace SerialInterface
diff --git a/Source/Core/Core/HW/SI/SI_DeviceGBA.cpp b/Source/Core/Core/HW/SI/SI_DeviceGBA.cpp
index 1b47887b28..806dfc2492 100644
--- a/Source/Core/Core/HW/SI/SI_DeviceGBA.cpp
+++ b/Source/Core/Core/HW/SI/SI_DeviceGBA.cpp
@@ -348,9 +348,9 @@ int CSIDevice_GBA::TransferInterval()
   return SIDevice_GetGBATransferTime(m_system.GetSystemTimers(), m_last_cmd);
 }
 
-bool CSIDevice_GBA::GetData(u32& hi, u32& low)
+DataResponse CSIDevice_GBA::GetData(u32& hi, u32& low)
 {
-  return false;
+  return DataResponse::NoData;
 }
 
 void CSIDevice_GBA::SendCommand(u32 command, u8 poll)
diff --git a/Source/Core/Core/HW/SI/SI_DeviceGBA.h b/Source/Core/Core/HW/SI/SI_DeviceGBA.h
index 52a1bb81f2..f7bc165f87 100644
--- a/Source/Core/Core/HW/SI/SI_DeviceGBA.h
+++ b/Source/Core/Core/HW/SI/SI_DeviceGBA.h
@@ -47,7 +47,7 @@ public:
 
   int RunBuffer(u8* buffer, int request_length) override;
   int TransferInterval() override;
-  bool GetData(u32& hi, u32& low) override;
+  DataResponse GetData(u32& hi, u32& low) override;
   void SendCommand(u32 command, u8 poll) override;
 
 private:
diff --git a/Source/Core/Core/HW/SI/SI_DeviceGBAEmu.cpp b/Source/Core/Core/HW/SI/SI_DeviceGBAEmu.cpp
index f0b899192d..a78b73e4c7 100644
--- a/Source/Core/Core/HW/SI/SI_DeviceGBAEmu.cpp
+++ b/Source/Core/Core/HW/SI/SI_DeviceGBAEmu.cpp
@@ -120,7 +120,7 @@ int CSIDevice_GBAEmu::TransferInterval()
   return SIDevice_GetGBATransferTime(m_system.GetSystemTimers(), m_last_cmd);
 }
 
-bool CSIDevice_GBAEmu::GetData(u32& hi, u32& low)
+DataResponse CSIDevice_GBAEmu::GetData(u32& hi, u32& low)
 {
   GCPadStatus pad_status{};
   if (!NetPlay::IsNetPlayRunning())
@@ -149,7 +149,7 @@ bool CSIDevice_GBAEmu::GetData(u32& hi, u32& low)
   if (pad_status.button & PadButton::PAD_BUTTON_X)
     m_core->Reset();
 
-  return false;
+  return DataResponse::NoData;
 }
 
 void CSIDevice_GBAEmu::SendCommand(u32 command, u8 poll)
diff --git a/Source/Core/Core/HW/SI/SI_DeviceGBAEmu.h b/Source/Core/Core/HW/SI/SI_DeviceGBAEmu.h
index 6f363c8896..a9677889ce 100644
--- a/Source/Core/Core/HW/SI/SI_DeviceGBAEmu.h
+++ b/Source/Core/Core/HW/SI/SI_DeviceGBAEmu.h
@@ -25,7 +25,7 @@ public:
 
   int RunBuffer(u8* buffer, int request_length) override;
   int TransferInterval() override;
-  bool GetData(u32& hi, u32& low) override;
+  DataResponse GetData(u32& hi, u32& low) override;
   void SendCommand(u32 command, u8 poll) override;
   void DoState(PointerWrap& p) override;
   void OnEvent(u64 userdata, s64 cycles_late) override;
diff --git a/Source/Core/Core/HW/SI/SI_DeviceGCAdapter.cpp b/Source/Core/Core/HW/SI/SI_DeviceGCAdapter.cpp
index 88747062f8..d520f43312 100644
--- a/Source/Core/Core/HW/SI/SI_DeviceGCAdapter.cpp
+++ b/Source/Core/Core/HW/SI/SI_DeviceGCAdapter.cpp
@@ -69,7 +69,7 @@ int CSIDevice_GCAdapter::RunBuffer(u8* buffer, int request_length)
   return CSIDevice_GCController::RunBuffer(buffer, request_length);
 }
 
-bool CSIDevice_GCAdapter::GetData(u32& hi, u32& low)
+DataResponse CSIDevice_GCAdapter::GetData(u32& hi, u32& low)
 {
   CSIDevice_GCController::GetData(hi, low);
 
@@ -78,7 +78,7 @@ bool CSIDevice_GCAdapter::GetData(u32& hi, u32& low)
     hi &= CSIDevice_TaruKonga::HI_BUTTON_MASK;
   }
 
-  return true;
+  return DataResponse::Success;
 }
 
 void CSIDevice_GCController::Rumble(int pad_num, ControlState strength, SIDevices device)
diff --git a/Source/Core/Core/HW/SI/SI_DeviceGCAdapter.h b/Source/Core/Core/HW/SI/SI_DeviceGCAdapter.h
index c9967ed671..9e9fa9a32b 100644
--- a/Source/Core/Core/HW/SI/SI_DeviceGCAdapter.h
+++ b/Source/Core/Core/HW/SI/SI_DeviceGCAdapter.h
@@ -17,7 +17,7 @@ public:
   GCPadStatus GetPadStatus() override;
   int RunBuffer(u8* buffer, int request_length) override;
 
-  bool GetData(u32& hi, u32& low) override;
+  DataResponse GetData(u32& hi, u32& low) override;
 
 private:
   bool m_simulate_konga{};
diff --git a/Source/Core/Core/HW/SI/SI_DeviceGCController.cpp b/Source/Core/Core/HW/SI/SI_DeviceGCController.cpp
index f3867cf1fc..dcc30fd4f9 100644
--- a/Source/Core/Core/HW/SI/SI_DeviceGCController.cpp
+++ b/Source/Core/Core/HW/SI/SI_DeviceGCController.cpp
@@ -170,12 +170,12 @@ GCPadStatus CSIDevice_GCController::GetPadStatus()
 // [00?SYXBA] [1LRZUDRL] [x] [y] [cx] [cy] [l] [r]
 //  |\_ ERR_LATCH (error latched - check SISR)
 //  |_ ERR_STATUS (error on last GetData or SendCmd?)
-bool CSIDevice_GCController::GetData(u32& hi, u32& low)
+DataResponse CSIDevice_GCController::GetData(u32& hi, u32& low)
 {
   GCPadStatus pad_status = GetPadStatus();
 
   if (!pad_status.isConnected)
-    return false;
+    return DataResponse::ErrorNoResponse;
 
   if (HandleButtonCombos(pad_status) == COMBO_ORIGIN)
     pad_status.button |= PAD_GET_ORIGIN;
@@ -227,7 +227,7 @@ bool CSIDevice_GCController::GetData(u32& hi, u32& low)
     low |= pad_status.substickX << 24;  // All 8 bits
   }
 
-  return true;
+  return DataResponse::Success;
 }
 
 u32 CSIDevice_GCController::MapPadStatus(const GCPadStatus& pad_status)
@@ -343,7 +343,7 @@ CSIDevice_TaruKonga::CSIDevice_TaruKonga(Core::System& system, SIDevices device,
 {
 }
 
-bool CSIDevice_TaruKonga::GetData(u32& hi, u32& low)
+DataResponse CSIDevice_TaruKonga::GetData(u32& hi, u32& low)
 {
   CSIDevice_GCController::GetData(hi, low);
 
@@ -351,7 +351,7 @@ bool CSIDevice_TaruKonga::GetData(u32& hi, u32& low)
   // and all buttons except: A, B, X, Y, Start, R
   hi &= HI_BUTTON_MASK;
 
-  return true;
+  return DataResponse::Success;
 }
 
 }  // namespace SerialInterface
diff --git a/Source/Core/Core/HW/SI/SI_DeviceGCController.h b/Source/Core/Core/HW/SI/SI_DeviceGCController.h
index 6c8996b53f..19b5bdb14b 100644
--- a/Source/Core/Core/HW/SI/SI_DeviceGCController.h
+++ b/Source/Core/Core/HW/SI/SI_DeviceGCController.h
@@ -63,8 +63,7 @@ public:
   // Run the SI Buffer
   int RunBuffer(u8* buffer, int request_length) override;
 
-  // Return true on new data
-  bool GetData(u32& hi, u32& low) override;
+  DataResponse GetData(u32& hi, u32& low) override;
 
   // Send a command directly
   void SendCommand(u32 command, u8 poll) override;
@@ -96,7 +95,7 @@ class CSIDevice_TaruKonga final : public CSIDevice_GCController
 public:
   CSIDevice_TaruKonga(Core::System& system, SIDevices device, int device_number);
 
-  bool GetData(u32& hi, u32& low) override;
+  DataResponse GetData(u32& hi, u32& low) override;
 
   static const u32 HI_BUTTON_MASK =
       (PAD_BUTTON_A | PAD_BUTTON_B | PAD_BUTTON_X | PAD_BUTTON_Y | PAD_BUTTON_START | PAD_TRIGGER_R)
diff --git a/Source/Core/Core/HW/SI/SI_DeviceGCSteeringWheel.cpp b/Source/Core/Core/HW/SI/SI_DeviceGCSteeringWheel.cpp
index 4e622a91bf..11bba73090 100644
--- a/Source/Core/Core/HW/SI/SI_DeviceGCSteeringWheel.cpp
+++ b/Source/Core/Core/HW/SI/SI_DeviceGCSteeringWheel.cpp
@@ -43,7 +43,7 @@ int CSIDevice_GCSteeringWheel::RunBuffer(u8* buffer, int request_length)
   }
 }
 
-bool CSIDevice_GCSteeringWheel::GetData(u32& hi, u32& low)
+DataResponse CSIDevice_GCSteeringWheel::GetData(u32& hi, u32& low)
 {
   if (m_mode == 6)
   {
@@ -95,7 +95,7 @@ bool CSIDevice_GCSteeringWheel::GetData(u32& hi, u32& low)
     return CSIDevice_GCController::GetData(hi, low);
   }
 
-  return true;
+  return DataResponse::Success;
 }
 
 void CSIDevice_GCSteeringWheel::SendCommand(u32 command, u8 poll)
diff --git a/Source/Core/Core/HW/SI/SI_DeviceGCSteeringWheel.h b/Source/Core/Core/HW/SI/SI_DeviceGCSteeringWheel.h
index 7c6a30ed21..b610c18e8f 100644
--- a/Source/Core/Core/HW/SI/SI_DeviceGCSteeringWheel.h
+++ b/Source/Core/Core/HW/SI/SI_DeviceGCSteeringWheel.h
@@ -13,7 +13,7 @@ public:
   CSIDevice_GCSteeringWheel(Core::System& system, SIDevices device, int device_number);
 
   int RunBuffer(u8* buffer, int request_length) override;
-  bool GetData(u32& hi, u32& low) override;
+  DataResponse GetData(u32& hi, u32& low) override;
   void SendCommand(u32 command, u8 poll) override;
 
 private:
diff --git a/Source/Core/Core/HW/SI/SI_DeviceKeyboard.cpp b/Source/Core/Core/HW/SI/SI_DeviceKeyboard.cpp
index 6c1e34b9bb..beb722dc82 100644
--- a/Source/Core/Core/HW/SI/SI_DeviceKeyboard.cpp
+++ b/Source/Core/Core/HW/SI/SI_DeviceKeyboard.cpp
@@ -68,7 +68,7 @@ KeyboardStatus CSIDevice_Keyboard::GetKeyboardStatus() const
   return Keyboard::GetStatus(m_device_number);
 }
 
-bool CSIDevice_Keyboard::GetData(u32& hi, u32& low)
+DataResponse CSIDevice_Keyboard::GetData(u32& hi, u32& low)
 {
   const KeyboardStatus key_status = GetKeyboardStatus();
   const KeyArray key = MapKeys(key_status);
@@ -77,7 +77,7 @@ bool CSIDevice_Keyboard::GetData(u32& hi, u32& low)
   hi = m_counter << 24;
   low = key[0] << 24 | key[1] << 16 | key[2] << 8 | checksum;
 
-  return true;
+  return DataResponse::Success;
 }
 
 void CSIDevice_Keyboard::SendCommand(u32 command, u8 poll)
diff --git a/Source/Core/Core/HW/SI/SI_DeviceKeyboard.h b/Source/Core/Core/HW/SI/SI_DeviceKeyboard.h
index 5738ac1f8d..1d2ca62c07 100644
--- a/Source/Core/Core/HW/SI/SI_DeviceKeyboard.h
+++ b/Source/Core/Core/HW/SI/SI_DeviceKeyboard.h
@@ -21,8 +21,7 @@ public:
   // Run the SI Buffer
   int RunBuffer(u8* buffer, int request_length) override;
 
-  // Return true on new data
-  bool GetData(u32& hi, u32& low) override;
+  DataResponse GetData(u32& hi, u32& low) override;
 
   KeyboardStatus GetKeyboardStatus() const;
 
diff --git a/Source/Core/Core/HW/SI/SI_DeviceNull.cpp b/Source/Core/Core/HW/SI/SI_DeviceNull.cpp
index 076765fd3c..213d32199e 100644
--- a/Source/Core/Core/HW/SI/SI_DeviceNull.cpp
+++ b/Source/Core/Core/HW/SI/SI_DeviceNull.cpp
@@ -15,9 +15,9 @@ int CSIDevice_Null::RunBuffer(u8* buffer, int request_length)
   return -1;
 }
 
-bool CSIDevice_Null::GetData(u32& hi, u32& low)
+DataResponse CSIDevice_Null::GetData(u32& hi, u32& low)
 {
-  return false;
+  return DataResponse::ErrorNoResponse;
 }
 
 void CSIDevice_Null::SendCommand(u32 command, u8 poll)
diff --git a/Source/Core/Core/HW/SI/SI_DeviceNull.h b/Source/Core/Core/HW/SI/SI_DeviceNull.h
index 0e20840bcf..cfd8603f48 100644
--- a/Source/Core/Core/HW/SI/SI_DeviceNull.h
+++ b/Source/Core/Core/HW/SI/SI_DeviceNull.h
@@ -15,7 +15,7 @@ public:
   CSIDevice_Null(Core::System& system, SIDevices device, int device_number);
 
   int RunBuffer(u8* buffer, int request_length) override;
-  bool GetData(u32& hi, u32& low) override;
+  DataResponse GetData(u32& hi, u32& low) override;
   void SendCommand(u32 command, u8 poll) override;
 };
 }  // namespace SerialInterface