DMA: Implement linked list mode

src/pse/gpu.cpp

@@ -1,6 +1,7 @@
 #include "gpu.h"
 #include "YBaseLib/Log.h"
 #include "bus.h"
+#include "dma.h"
 Log_SetChannel(GPU);
 
 GPU::GPU() = default;
@@ -22,34 +23,70 @@ void GPU::Reset()
 void GPU::SoftReset()
 {
   m_GPUSTAT.bits = 0x14802000;
+  UpdateDMARequest();
+}
+
+void GPU::UpdateDMARequest()
+{
+  const bool request = m_GPUSTAT.dma_direction != DMADirection::Off;
+  m_GPUSTAT.dma_data_request = request;
+  m_dma->SetRequest(DMA::Channel::GPU, request);
 }
 
 u32 GPU::ReadRegister(u32 offset)
 {
-  if (offset == 0x00)
+  switch (offset)
   {
-    // GPUREAD
-    Log_ErrorPrintf("GPUREAD");
-    return 0;
-  }
-  else if (offset == 0x04)
-  {
-    // GPUSTAT
-    return m_GPUSTAT.bits;
-  }
+    case 0x00:
+      return ReadGPUREAD();
 
-  Log_ErrorPrintf("Unhandled register read: %02X", offset);
-  return UINT32_C(0xFFFFFFFF);
+    case 0x04:
+      return m_GPUSTAT.bits;
+
+    default:
+      Log_ErrorPrintf("Unhandled register read: %02X", offset);
+      return UINT32_C(0xFFFFFFFF);
+  }
 }
 
 void GPU::WriteRegister(u32 offset, u32 value)
 {
-  if (offset == 0x00)
-    WriteGP0(value);
-  else if (offset == 0x04)
-    WriteGP1(value);
-  else
-    Log_ErrorPrintf("Unhandled register write: %02X <- %08X", offset, value);
+  switch (offset)
+  {
+    case 0x00:
+      WriteGP0(value);
+      return;
+
+    case 0x04:
+      WriteGP1(value);
+      return;
+
+    default:
+      Log_ErrorPrintf("Unhandled register write: %02X <- %08X", offset, value);
+      return;
+  }
+}
+
+u32 GPU::DMARead()
+{
+  if (m_GPUSTAT.dma_direction != DMADirection::GPUREADtoCPU)
+  {
+    Log_ErrorPrintf("Invalid DMA direction from GPU DMA read");
+    return UINT32_C(0xFFFFFFFF);
+  }
+
+  return ReadGPUREAD();
+}
+
+void GPU::DMAWrite(u32 value)
+{
+  Log_ErrorPrintf("GPU DMA Write %08X", value);
+}
+
+u32 GPU::ReadGPUREAD()
+{
+  Log_ErrorPrintf("GPUREAD not implemented");
+  return UINT32_C(0xFFFFFFFF);
 }
 
 void GPU::WriteGP0(u32 value)
@@ -61,5 +98,19 @@ void GPU::WriteGP0(u32 value)
 void GPU::WriteGP1(u32 value)
 {
   const u8 command = Truncate8(value >> 24);
-  Log_ErrorPrintf("Unimplemented GP1 command 0x%02X", command);
+  const u32 param = value & UINT32_C(0x00FFFFFF);
+  switch (command)
+  {
+    case 0x04: // DMA Direction
+    {
+      m_GPUSTAT.dma_direction = static_cast<DMADirection>(param);
+      Log_DebugPrintf("DMA direction <- 0x%02X", static_cast<u32>(m_GPUSTAT.dma_direction.GetValue()));
+      UpdateDMARequest();
+    }
+    break;
+
+    default:
+      Log_ErrorPrintf("Unimplemented GP1 command 0x%02X", command);
+      break;
+  }
 }