Implement experimental Vulkan backend

Source/Core/VideoBackends/Vulkan/StreamBuffer.h

@@ -0,0 +1,59 @@
+// Copyright 2016 Dolphin Emulator Project
+// Licensed under GPLv2+
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include <deque>
+#include <memory>
+#include <utility>
+
+#include "VideoBackends/Vulkan/Constants.h"
+
+namespace Vulkan
+{
+class StreamBuffer
+{
+public:
+  StreamBuffer(VkBufferUsageFlags usage, size_t max_size);
+  ~StreamBuffer();
+
+  VkBuffer GetBuffer() const { return m_buffer; }
+  VkDeviceMemory GetDeviceMemory() const { return m_memory; }
+  u8* GetHostPointer() const { return m_host_pointer; }
+  u8* GetCurrentHostPointer() const { return m_host_pointer + m_current_offset; }
+  size_t GetCurrentSize() const { return m_current_size; }
+  size_t GetCurrentOffset() const { return m_current_offset; }
+  bool ReserveMemory(size_t num_bytes, size_t alignment, bool allow_reuse = true,
+                     bool allow_growth = true, bool reallocate_if_full = false);
+  void CommitMemory(size_t final_num_bytes);
+
+  static std::unique_ptr<StreamBuffer> Create(VkBufferUsageFlags usage, size_t initial_size,
+                                              size_t max_size);
+
+private:
+  bool ResizeBuffer(size_t size);
+  void OnCommandBufferQueued(VkCommandBuffer command_buffer, VkFence fence);
+  void OnCommandBufferExecuted(VkFence fence);
+
+  // Waits for as many fences as needed to allocate num_bytes bytes from the buffer.
+  bool WaitForClearSpace(size_t num_bytes);
+
+  VkBufferUsageFlags m_usage;
+  size_t m_current_size = 0;
+  size_t m_maximum_size;
+  size_t m_current_offset = 0;
+  size_t m_current_gpu_position = 0;
+  size_t m_last_allocation_size = 0;
+
+  VkBuffer m_buffer = VK_NULL_HANDLE;
+  VkDeviceMemory m_memory = VK_NULL_HANDLE;
+  u8* m_host_pointer = nullptr;
+
+  // List of fences and the corresponding positions in the buffer
+  std::deque<std::pair<VkFence, size_t>> m_tracked_fences;
+
+  bool m_coherent_mapping = false;
+};
+
+}  // namespace Vulkan