GPU: Eliminate temporary buffer when reading back

src/core/gpu.cpp

@@ -1,5 +1,6 @@
 #include "gpu.h"
 #include "YBaseLib/Log.h"
+#include "common/heap_array.h"
 #include "common/state_wrapper.h"
 #include "dma.h"
 #include "host_interface.h"
@@ -127,16 +128,16 @@ bool GPU::DoState(StateWrapper& sw)
 
   if (sw.IsReading())
   {
-    std::vector<u16> vram;
-    sw.Do(&vram);
-    UpdateVRAM(0, 0, VRAM_WIDTH, VRAM_HEIGHT, vram.data());
+    // Still need a temporary here.
+    HeapArray<u16, VRAM_WIDTH * VRAM_HEIGHT> temp;
+    sw.DoBytes(temp.data(), VRAM_WIDTH * VRAM_HEIGHT * sizeof(u16));
+    UpdateVRAM(0, 0, VRAM_WIDTH, VRAM_HEIGHT, temp.data());
     UpdateDisplay();
   }
   else
   {
-    std::vector<u16> vram(VRAM_WIDTH * VRAM_HEIGHT);
-    ReadVRAM(0, 0, VRAM_WIDTH, VRAM_HEIGHT, vram.data());
-    sw.Do(&vram);
+    ReadVRAM(0, 0, VRAM_WIDTH, VRAM_HEIGHT);
+    sw.DoBytes(m_vram_ptr, VRAM_WIDTH * VRAM_HEIGHT * sizeof(u16));
   }
 
   return !sw.HasError();
@@ -693,7 +694,7 @@ void GPU::HandleGetGPUInfoCommand(u32 value)
 
 void GPU::UpdateDisplay() {}
 
-void GPU::ReadVRAM(u32 x, u32 y, u32 width, u32 height, void* buffer) {}
+void GPU::ReadVRAM(u32 x, u32 y, u32 width, u32 height) {}
 
 void GPU::FillVRAM(u32 x, u32 y, u32 width, u32 height, u32 color) {}
 

src/core/gpu.h

@@ -288,7 +288,7 @@ protected:
   void HandleGetGPUInfoCommand(u32 value);
 
   // Rendering in the backend
-  virtual void ReadVRAM(u32 x, u32 y, u32 width, u32 height, void* buffer);
+  virtual void ReadVRAM(u32 x, u32 y, u32 width, u32 height);
   virtual void FillVRAM(u32 x, u32 y, u32 width, u32 height, u32 color);
   virtual void UpdateVRAM(u32 x, u32 y, u32 width, u32 height, const void* data);
   virtual void CopyVRAM(u32 src_x, u32 src_y, u32 dst_x, u32 dst_y, u32 width, u32 height);
@@ -303,6 +303,9 @@ protected:
   InterruptController* m_interrupt_controller = nullptr;
   Timers* m_timers = nullptr;
 
+  // Pointer to VRAM, used for reads/writes. In the hardware backends, this is the shadow buffer.
+  u16* m_vram_ptr = nullptr;
+
   union GPUSTAT
   {
     u32 bits;

src/core/gpu_commands.cpp

@@ -330,14 +330,24 @@ bool GPU::HandleCopyRectangleVRAMToCPUCommand(const u32*& command_ptr, u32 comma
   // all rendering should be done first...
   FlushRender();
 
-  // TODO: A better way of doing this..
-  std::vector<u32> temp(num_words);
-  ReadVRAM(src_x, src_y, width, height, temp.data());
-  for (const u32 bits : temp)
-    m_GPUREAD_buffer.push_back(bits);
+  // TODO: A better way of doing this.. get rid of the m_GPUREAD_buffer.
+  ReadVRAM(src_x, src_y, width, height);
+  for (u32 row = 0; row < height;)
+  {
+    const u32 row_offset = ((src_y + row++) % VRAM_HEIGHT) * VRAM_WIDTH;
+    for (u32 col = 0; col < width;)
+    {
+      // TODO: Handle unaligned reads...
+      const u32 col_offset1 = row_offset + ((src_x + col++) % VRAM_WIDTH);
+      const u32 col_offset2 = row_offset + ((src_x + col++) % VRAM_WIDTH);
+      m_GPUREAD_buffer.push_back(ZeroExtend32(m_vram_ptr[col_offset1]) | (ZeroExtend32(m_vram_ptr[col_offset2]) << 16));
+    }
+  }
 
   if (m_system->GetSettings().debugging.dump_vram_to_cpu_copies)
   {
+    std::vector<u32> temp;
+    std::copy(m_GPUREAD_buffer.begin(), m_GPUREAD_buffer.end(), std::back_inserter(temp));
     DumpVRAMToFile(SmallString::FromFormat("vram_to_cpu_copy_%u.png", s_vram_to_cpu_dump_id++), width, height,
                    sizeof(u16) * width, temp.data(), true);
   }

src/core/gpu_hw.cpp

@@ -8,7 +8,10 @@
 #include <sstream>
 Log_SetChannel(GPU_HW);
 
-GPU_HW::GPU_HW() = default;
+GPU_HW::GPU_HW() : GPU()
+{
+  m_vram_ptr = m_vram_shadow.data();
+}
 
 GPU_HW::~GPU_HW() = default;
 
@@ -209,22 +212,6 @@ GPU_HW::BatchPrimitive GPU_HW::GetPrimitiveForCommand(RenderCommand rc)
     return BatchPrimitive::Triangles;
 }
 
-void GPU_HW::ReadVRAM(u32 x, u32 y, u32 width, u32 height, void* buffer)
-{
-  u8* out_ptr = static_cast<u8*>(buffer);
-
-  for (u32 row = 0; row < height; row++)
-  {
-    const u32 row_offset = ((y + row) % VRAM_HEIGHT) * VRAM_WIDTH;
-    for (u32 col = 0; col < width; col++)
-    {
-      const u32 col_offset = row_offset + ((x + col) % VRAM_WIDTH);
-      std::memcpy(out_ptr, &m_vram_shadow[col_offset], sizeof(u16));
-      out_ptr += sizeof(u16);
-    }
-  }
-}
-
 void GPU_HW::FillVRAM(u32 x, u32 y, u32 width, u32 height, u32 color)
 {
   m_vram_dirty_rect.Include(Common::Rectangle<u32>::FromExtents(x, y, width, height));

src/core/gpu_hw.h

@@ -127,7 +127,6 @@ protected:
 
   bool IsFlushed() const { return m_batch_current_vertex_ptr == m_batch_start_vertex_ptr; }
 
-  void ReadVRAM(u32 x, u32 y, u32 width, u32 height, void* buffer) override;
   void FillVRAM(u32 x, u32 y, u32 width, u32 height, u32 color) override;
   void UpdateVRAM(u32 x, u32 y, u32 width, u32 height, const void* data) override;
   void CopyVRAM(u32 src_x, u32 src_y, u32 dst_x, u32 dst_y, u32 width, u32 height) override;

src/core/gpu_hw_d3d11.cpp

@@ -584,7 +584,7 @@ void GPU_HW_D3D11::UpdateDisplay()
   }
 }
 
-void GPU_HW_D3D11::ReadVRAM(u32 x, u32 y, u32 width, u32 height, void* buffer)
+void GPU_HW_D3D11::ReadVRAM(u32 x, u32 y, u32 width, u32 height)
 {
   // Get bounds with wrap-around handled.
   const Common::Rectangle<u32> copy_rect = GetVRAMTransferBounds(x, y, width, height);
@@ -614,9 +614,6 @@ void GPU_HW_D3D11::ReadVRAM(u32 x, u32 y, u32 width, u32 height, void* buffer)
   }
 
   RestoreGraphicsAPIState();
-
-  // Feed the shadow buffer back to the output.
-  GPU_HW::ReadVRAM(x, y, width, height, buffer);
 }
 
 void GPU_HW_D3D11::FillVRAM(u32 x, u32 y, u32 width, u32 height, u32 color)

src/core/gpu_hw_d3d11.h

@@ -28,7 +28,7 @@ public:
 
 protected:
   void UpdateDisplay() override;
-  void ReadVRAM(u32 x, u32 y, u32 width, u32 height, void* buffer) override;
+  void ReadVRAM(u32 x, u32 y, u32 width, u32 height) override;
   void FillVRAM(u32 x, u32 y, u32 width, u32 height, u32 color) override;
   void UpdateVRAM(u32 x, u32 y, u32 width, u32 height, const void* data) override;
   void CopyVRAM(u32 src_x, u32 src_y, u32 dst_x, u32 dst_y, u32 width, u32 height) override;

src/core/gpu_hw_opengl.cpp

@@ -526,7 +526,7 @@ void GPU_HW_OpenGL::UpdateDisplay()
   }
 }
 
-void GPU_HW_OpenGL::ReadVRAM(u32 x, u32 y, u32 width, u32 height, void* buffer)
+void GPU_HW_OpenGL::ReadVRAM(u32 x, u32 y, u32 width, u32 height)
 {
   // Get bounds with wrap-around handled.
   const Common::Rectangle<u32> copy_rect = GetVRAMTransferBounds(x, y, width, height);
@@ -554,9 +554,6 @@ void GPU_HW_OpenGL::ReadVRAM(u32 x, u32 y, u32 width, u32 height, void* buffer)
   glPixelStorei(GL_PACK_ALIGNMENT, 4);
   glPixelStorei(GL_PACK_ROW_LENGTH, 0);
   RestoreGraphicsAPIState();
-
-  // Feed the shadow buffer back to the output.
-  GPU_HW::ReadVRAM(x, y, width, height, buffer);
 }
 
 void GPU_HW_OpenGL::FillVRAM(u32 x, u32 y, u32 width, u32 height, u32 color)

src/core/gpu_hw_opengl.h

@@ -24,7 +24,7 @@ public:
 
 protected:
   void UpdateDisplay() override;
-  void ReadVRAM(u32 x, u32 y, u32 width, u32 height, void* buffer) override;
+  void ReadVRAM(u32 x, u32 y, u32 width, u32 height) override;
   void FillVRAM(u32 x, u32 y, u32 width, u32 height, u32 color) override;
   void UpdateVRAM(u32 x, u32 y, u32 width, u32 height, const void* data) override;
   void CopyVRAM(u32 src_x, u32 src_y, u32 dst_x, u32 dst_y, u32 width, u32 height) override;

src/core/gpu_sw.cpp

@@ -10,6 +10,7 @@ Log_SetChannel(GPU_SW);
 GPU_SW::GPU_SW()
 {
   m_vram.fill(0);
+  m_vram_ptr = m_vram.data();
 }
 
 GPU_SW::~GPU_SW()
@@ -37,15 +38,9 @@ void GPU_SW::Reset()
   m_vram.fill(0);
 }
 
-void GPU_SW::ReadVRAM(u32 x, u32 y, u32 width, u32 height, void* buffer)
+void GPU_SW::ReadVRAM(u32 x, u32 y, u32 width, u32 height)
 {
-  u16* buffer_ptr = static_cast<u16*>(buffer);
-  for (u32 yoffs = 0; yoffs < height; yoffs++)
-  {
-    u16* src_ptr = GetPixelPtr(x, y + yoffs);
-    std::copy_n(src_ptr, width, buffer_ptr);
-    buffer_ptr += width;
-  }
+  // No need to do anything - pointer is already up to date.
 }
 
 void GPU_SW::FillVRAM(u32 x, u32 y, u32 width, u32 height, u32 color)

src/core/gpu_sw.h

@@ -34,7 +34,7 @@ protected:
     u8 texcoord_x, texcoord_y;
   };
 
-  void ReadVRAM(u32 x, u32 y, u32 width, u32 height, void* buffer) override;
+  void ReadVRAM(u32 x, u32 y, u32 width, u32 height) override;
   void FillVRAM(u32 x, u32 y, u32 width, u32 height, u32 color) override;
   void UpdateVRAM(u32 x, u32 y, u32 width, u32 height, const void* data) override;
   void CopyVRAM(u32 src_x, u32 src_y, u32 dst_x, u32 dst_y, u32 width, u32 height) override;