Implement D3D12 backend

Source/Core/VideoBackends/D3D12/Common.h

@@ -0,0 +1,32 @@
+// Copyright 2019 Dolphin Emulator Project
+// Licensed under GPLv2+
+// Refer to the license.txt file included.
+#pragma once
+
+#include <d3d12.h>
+#include <wrl/client.h>
+
+#include "Common/MsgHandler.h"
+#include "VideoBackends/D3DCommon/Common.h"
+
+#define CHECK(cond, Message, ...)                                                                  \
+  if (!(cond))                                                                                     \
+  {                                                                                                \
+    PanicAlert(__FUNCTION__ " failed in %s at line %d: " Message, __FILE__, __LINE__,              \
+               __VA_ARGS__);                                                                       \
+  }
+
+namespace DX12
+{
+using Microsoft::WRL::ComPtr;
+
+static void ResourceBarrier(ID3D12GraphicsCommandList* cmdlist, ID3D12Resource* resource,
+                            D3D12_RESOURCE_STATES from_state, D3D12_RESOURCE_STATES to_state)
+{
+  const D3D12_RESOURCE_BARRIER barrier = {
+      D3D12_RESOURCE_BARRIER_TYPE_TRANSITION,
+      D3D12_RESOURCE_BARRIER_FLAG_NONE,
+      {{resource, D3D12_RESOURCE_BARRIER_ALL_SUBRESOURCES, from_state, to_state}}};
+  cmdlist->ResourceBarrier(1, &barrier);
+}
+}  // namespace DX12