Vulkan Circular Buffer

src/xenia/ui/vulkan/circular_buffer.h

@@ -0,0 +1,85 @@
+/**
+ ******************************************************************************
+ * Xenia : Xbox 360 Emulator Research Project                                 *
+ ******************************************************************************
+ * Copyright 2015 Ben Vanik. All rights reserved.                             *
+ * Released under the BSD license - see LICENSE in the root for more details. *
+ ******************************************************************************
+ */
+
+#ifndef XENIA_UI_VULKAN_CIRCULAR_BUFFER_H_
+#define XENIA_UI_VULKAN_CIRCULAR_BUFFER_H_
+
+#include <unordered_map>
+
+#include "xenia/ui/vulkan/vulkan.h"
+#include "xenia/ui/vulkan/vulkan_device.h"
+
+namespace xe {
+namespace ui {
+namespace vulkan {
+
+// A circular buffer, intended to hold (fairly) temporary memory that will be
+// released when a fence is signaled. Best used when allocations are taken
+// in-order with command buffer submission.
+//
+// Allocations loop around the buffer in circles (but are not fragmented at the
+// ends of the buffer), where trailing older allocations are freed after use.
+class CircularBuffer {
+ public:
+  CircularBuffer(VulkanDevice* device);
+  ~CircularBuffer();
+
+  struct Allocation {
+    void* host_ptr;
+    VkDeviceMemory gpu_memory;
+    VkDeviceSize offset;
+    VkDeviceSize length;
+    VkDeviceSize aligned_length;
+
+    // Allocation usage fence. This allocation will be deleted when the fence
+    // becomes signaled.
+    std::shared_ptr<Fence> fence;
+  };
+
+  bool Initialize(VkDeviceSize capacity, VkBufferUsageFlags usage,
+                  VkDeviceSize alignment = 256);
+  void Shutdown();
+
+  VkDeviceSize capacity() const { return capacity_; }
+  VkBuffer gpu_buffer() const { return gpu_buffer_; }
+  VkDeviceMemory gpu_memory() const { return gpu_memory_; }
+  uint8_t* host_base() const { return host_base_; }
+
+  bool CanAcquire(VkDeviceSize length);
+  Allocation* Acquire(VkDeviceSize length, std::shared_ptr<Fence> fence);
+  void Discard(Allocation* allocation);
+  void Flush(Allocation* allocation);
+
+  // Clears all allocations, regardless of whether they've been consumed or not.
+  void Clear();
+
+  // Frees any allocations whose fences have been signaled.
+  void Scavenge();
+
+ private:
+  VkDeviceSize capacity_ = 0;
+  VkDeviceSize alignment_ = 0;
+  VkDeviceSize write_head_ = 0;
+  VkDeviceSize read_head_ = 0;
+
+  VulkanDevice* device_;
+  VkBuffer gpu_buffer_ = nullptr;
+  VkDeviceMemory gpu_memory_ = nullptr;
+  VkDeviceSize gpu_base_ = 0;
+  uint8_t* host_base_ = nullptr;
+
+  std::unordered_map<uint64_t, uintptr_t> allocation_cache_;
+  std::vector<Allocation*> allocations_;
+};
+
+}  // namespace vulkan
+}  // namespace ui
+}  // namespace xe
+
+#endif  // XENIA_UI_GL_CIRCULAR_BUFFER_H_