From 970deb452e32074d817d60b9f8dae23e3b2ebac4 Mon Sep 17 00:00:00 2001
From: Philip Rebohle <philip.rebohle@tu-dortmund.de>
Date: Fri, 21 Jun 2019 15:56:41 +0200
Subject: [PATCH] [dxvk] Implement new staging buffer allocator

---
 src/dxvk/dxvk_staging.cpp | 56 +++++++++++++++++++++++++++++++++++++++
 src/dxvk/dxvk_staging.h   | 40 ++++++++++++++++++++++++++++
 2 files changed, 96 insertions(+)

diff --git a/src/dxvk/dxvk_staging.cpp b/src/dxvk/dxvk_staging.cpp
index 943a5053..4ea8a66f 100644
--- a/src/dxvk/dxvk_staging.cpp
+++ b/src/dxvk/dxvk_staging.cpp
@@ -89,5 +89,61 @@ namespace dxvk {
     
     m_stagingBuffers.resize(0);
   }
+
+
+  DxvkStagingDataAlloc::DxvkStagingDataAlloc(const Rc<DxvkDevice>& device)
+  : m_device(device) {
+
+  }
+
+
+  DxvkStagingDataAlloc::~DxvkStagingDataAlloc() {
+
+  }
+
+
+  DxvkBufferSlice DxvkStagingDataAlloc::alloc(VkDeviceSize align, VkDeviceSize size) {
+    if (size > MaxBufferSize)
+      return DxvkBufferSlice(createBuffer(size));
+    
+    if (m_buffer == nullptr)
+      m_buffer = createBuffer(MaxBufferSize);
+    
+    if (!m_buffer->isInUse())
+      m_offset = 0;
+    
+    m_offset = dxvk::align(m_offset, align);
+
+    if (m_offset + size > MaxBufferSize) {
+      m_offset = 0;
+
+      if (m_buffers.size() < MaxBufferCount)
+        m_buffers.push(std::move(m_buffer));
+
+      if (!m_buffers.front()->isInUse()) {
+        m_buffer = std::move(m_buffers.front());
+        m_buffers.pop();
+      } else {
+        m_buffer = createBuffer(MaxBufferSize);
+      }
+    }
+
+    DxvkBufferSlice slice(m_buffer, m_offset, size);
+    m_offset = dxvk::align(m_offset + size, align);
+    return slice;
+  }
+
+
+  Rc<DxvkBuffer> DxvkStagingDataAlloc::createBuffer(VkDeviceSize size) {
+    DxvkBufferCreateInfo info;
+    info.size   = size;
+    info.usage  = VK_BUFFER_USAGE_TRANSFER_SRC_BIT;
+    info.stages = VK_PIPELINE_STAGE_TRANSFER_BIT;
+    info.access = VK_ACCESS_TRANSFER_READ_BIT;
+
+    return m_device->createBuffer(info,
+      VK_MEMORY_PROPERTY_HOST_VISIBLE_BIT |
+      VK_MEMORY_PROPERTY_HOST_COHERENT_BIT);
+  }
   
 }
diff --git a/src/dxvk/dxvk_staging.h b/src/dxvk/dxvk_staging.h
index 6d876dc9..f76c9ecf 100644
--- a/src/dxvk/dxvk_staging.h
+++ b/src/dxvk/dxvk_staging.h
@@ -1,5 +1,7 @@
 #pragma once
 
+#include <queue>
+
 #include "dxvk_buffer.h"
 
 namespace dxvk {
@@ -118,5 +120,43 @@ namespace dxvk {
     std::vector<Rc<DxvkStagingBuffer>> m_stagingBuffers;
     
   };
+
+
+  /**
+   * \brief Staging data allocator
+   *
+   * Allocates buffer slices for resource uploads,
+   * while trying to keep the number of allocations
+   * but also the amount of allocated memory low.
+   */
+  class DxvkStagingDataAlloc {
+    constexpr static VkDeviceSize MaxBufferSize  = 1 << 24; // 16 MiB
+    constexpr static uint32_t     MaxBufferCount = 2;
+  public:
+
+    DxvkStagingDataAlloc(const Rc<DxvkDevice>& device);
+
+    ~DxvkStagingDataAlloc();
+
+    /**
+     * \brief Alloctaes a staging buffer slice
+     * 
+     * \param [in] align Alignment of the allocation
+     * \param [in] size Size of the allocation
+     * \returns Staging buffer slice
+     */
+    DxvkBufferSlice alloc(VkDeviceSize align, VkDeviceSize size);
+
+  private:
+
+    Rc<DxvkDevice>  m_device;
+    Rc<DxvkBuffer>  m_buffer;
+    VkDeviceSize    m_offset = 0;
+
+    std::queue<Rc<DxvkBuffer>> m_buffers;
+
+    Rc<DxvkBuffer> createBuffer(VkDeviceSize size);
+
+  };
   
 }