From 0bc19472e8f79c1b1d4fb77d0bd4d966641e144d Mon Sep 17 00:00:00 2001
From: Philip Rebohle <philip.rebohle@tu-dortmund.de>
Date: Sat, 12 Feb 2022 16:45:13 +0100
Subject: [PATCH] [dxvk] Introduce DxvkStagingBuffer

---
 src/dxvk/dxvk_staging.cpp | 53 +++++++++++++++++++++++++++++++++++++++
 src/dxvk/dxvk_staging.h   | 52 +++++++++++++++++++++++++++++++++++++-
 2 files changed, 104 insertions(+), 1 deletion(-)

diff --git a/src/dxvk/dxvk_staging.cpp b/src/dxvk/dxvk_staging.cpp
index dd2a1fd2..6882861f 100644
--- a/src/dxvk/dxvk_staging.cpp
+++ b/src/dxvk/dxvk_staging.cpp
@@ -66,5 +66,58 @@ namespace dxvk {
       VK_MEMORY_PROPERTY_HOST_VISIBLE_BIT |
       VK_MEMORY_PROPERTY_HOST_COHERENT_BIT);
   }
+
+
+  DxvkStagingBuffer::DxvkStagingBuffer(
+    const Rc<DxvkDevice>&     device,
+          VkDeviceSize        size)
+  : m_device(device), m_offset(0), m_size(size) {
+
+  }
+
+
+  DxvkStagingBuffer::~DxvkStagingBuffer() {
+
+  }
+
+
+  DxvkBufferSlice DxvkStagingBuffer::alloc(VkDeviceSize align, VkDeviceSize size) {
+    DxvkBufferCreateInfo info;
+    info.size   = size;
+    info.usage  = VK_BUFFER_USAGE_TRANSFER_SRC_BIT
+                | VK_BUFFER_USAGE_UNIFORM_TEXEL_BUFFER_BIT
+                | VK_BUFFER_USAGE_STORAGE_BUFFER_BIT;
+    info.stages = VK_PIPELINE_STAGE_TRANSFER_BIT
+                | VK_PIPELINE_STAGE_COMPUTE_SHADER_BIT
+                | VK_PIPELINE_STAGE_FRAGMENT_SHADER_BIT;
+    info.access = VK_ACCESS_TRANSFER_READ_BIT
+                | VK_ACCESS_SHADER_READ_BIT;
+
+    VkDeviceSize alignedSize = dxvk::align(size, align);
+    VkDeviceSize alignedOffset = dxvk::align(m_offset, align);
+
+    if (alignedSize >= m_size) {
+      return DxvkBufferSlice(m_device->createBuffer(info,
+        VK_MEMORY_PROPERTY_HOST_VISIBLE_BIT | VK_MEMORY_PROPERTY_HOST_COHERENT_BIT));
+    }
+
+    if (alignedOffset + alignedSize > m_size || m_buffer == nullptr) {
+      info.size = m_size;
+
+      m_buffer = m_device->createBuffer(info,
+        VK_MEMORY_PROPERTY_HOST_VISIBLE_BIT | VK_MEMORY_PROPERTY_HOST_COHERENT_BIT);
+      alignedOffset = 0;
+    }
+
+    DxvkBufferSlice slice(m_buffer, alignedOffset, size);
+    m_offset = alignedOffset + alignedSize;
+    return slice;
+  }
+
+
+  void DxvkStagingBuffer::reset() {
+    m_buffer = nullptr;
+    m_offset = 0;
+  }
   
 }
diff --git a/src/dxvk/dxvk_staging.h b/src/dxvk/dxvk_staging.h
index 8eccd4f5..b2a591ac 100644
--- a/src/dxvk/dxvk_staging.h
+++ b/src/dxvk/dxvk_staging.h
@@ -52,5 +52,55 @@ namespace dxvk {
     Rc<DxvkBuffer> createBuffer(VkDeviceSize size);
 
   };
-  
+
+  /**
+   * \brief Staging buffer
+   *
+   * Provides a simple linear staging buffer
+   * allocator for data uploads.
+   */
+  class DxvkStagingBuffer {
+
+  public:
+
+    /**
+     * \brief Creates staging buffer
+     *
+     * \param [in] device DXVK device
+     * \param [in] size Buffer size
+     */
+    DxvkStagingBuffer(
+      const Rc<DxvkDevice>&     device,
+            VkDeviceSize        size);
+
+    /**
+     * \brief Frees staging buffer
+     */
+    ~DxvkStagingBuffer();
+
+    /**
+     * \brief Allocates staging buffer memory
+     *
+     * Tries to suballocate from existing buffer,
+     * or creates a new buffer if necessary.
+     * \param [in] align Minimum alignment
+     * \param [in] size Number of bytes to allocate
+     * \returns Allocated slice
+     */
+    DxvkBufferSlice alloc(VkDeviceSize align, VkDeviceSize size);
+
+    /**
+     * \brief Resets staging buffer and allocator
+     */
+    void reset();
+
+  private:
+
+    Rc<DxvkDevice>  m_device;
+    Rc<DxvkBuffer>  m_buffer;
+    VkDeviceSize    m_offset;
+    VkDeviceSize    m_size;
+
+  };
+
 }