Implement D3D12 backend

Source/Core/VideoBackends/D3D12/DescriptorHeapManager.h

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+// Copyright 2019 Dolphin Emulator Project
+// Licensed under GPLv2+
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include <bitset>
+#include <unordered_map>
+#include "VideoBackends/D3D12/Common.h"
+#include "VideoCommon/RenderState.h"
+
+namespace DX12
+{
+// This class provides an abstraction for D3D12 descriptor heaps.
+struct DescriptorHandle final
+{
+  D3D12_CPU_DESCRIPTOR_HANDLE cpu_handle;
+  D3D12_GPU_DESCRIPTOR_HANDLE gpu_handle;
+  u32 index;
+
+  operator bool() const { return cpu_handle.ptr != 0; }
+};
+
+class DescriptorHeapManager final
+{
+public:
+  DescriptorHeapManager();
+  ~DescriptorHeapManager();
+
+  ID3D12DescriptorHeap* GetDescriptorHeap() const { return m_descriptor_heap.Get(); }
+  u32 GetDescriptorIncrementSize() const { return m_descriptor_increment_size; }
+
+  bool Create(ID3D12Device* device, D3D12_DESCRIPTOR_HEAP_TYPE type, u32 num_descriptors);
+
+  bool Allocate(DescriptorHandle* handle);
+  void Free(const DescriptorHandle& handle);
+  void Free(u32 index);
+
+private:
+  ComPtr<ID3D12DescriptorHeap> m_descriptor_heap;
+  u32 m_num_descriptors = 0;
+  u32 m_descriptor_increment_size = 0;
+
+  D3D12_CPU_DESCRIPTOR_HANDLE m_heap_base_cpu = {};
+  D3D12_GPU_DESCRIPTOR_HANDLE m_heap_base_gpu = {};
+
+  static constexpr u32 BITSET_SIZE = 1024;
+  using BitSetType = std::bitset<BITSET_SIZE>;
+  std::vector<BitSetType> m_free_slots = {};
+};
+
+class SamplerHeapManager final
+{
+public:
+  SamplerHeapManager();
+  ~SamplerHeapManager();
+
+  ID3D12DescriptorHeap* GetDescriptorHeap() const { return m_descriptor_heap.Get(); }
+
+  bool Create(ID3D12Device* device, u32 num_descriptors);
+  bool Lookup(const SamplerState& ss, D3D12_CPU_DESCRIPTOR_HANDLE* handle);
+  void Clear();
+
+private:
+  ComPtr<ID3D12DescriptorHeap> m_descriptor_heap;
+  u32 m_num_descriptors = 0;
+  u32 m_descriptor_increment_size = 0;
+  u32 m_current_offset = 0;
+
+  D3D12_CPU_DESCRIPTOR_HANDLE m_heap_base_cpu;
+
+  std::unordered_map<SamplerState::StorageType, D3D12_CPU_DESCRIPTOR_HANDLE> m_sampler_map;
+};
+}  // namespace DX12