[dxvk] Introduce DxvkBufferSliceHandle

This struct is meant to replace DxvkPhysicalBufferSlice in the long
run, in a way that doesn't require extra reference counting.

src/dxvk/dxvk_buffer.h

@@ -7,6 +7,21 @@
 
 namespace dxvk {
 
+  /**
+   * \brief Buffer slice info
+   * 
+   * Stores the Vulkan buffer handle, offset
+   * and length of the slice, and a pointer
+   * to the mapped region..
+   */
+  struct DxvkBufferSliceHandle {
+    VkBuffer      handle;
+    VkDeviceSize  offset;
+    VkDeviceSize  length;
+    void*         mapPtr;
+  };
+
+  
   /**
    * \brief Virtual buffer resource
    * 
@@ -70,12 +85,40 @@ namespace dxvk {
       return m_physSlice.resource()->isInUse();
     }
 
+    /**
+     * \brief Retrieves slice handle
+     * \returns Buffer slice handle
+     */
+    DxvkBufferSliceHandle getSliceHandle() const {
+      DxvkBufferSliceHandle result;
+      result.handle = m_physSlice.handle();
+      result.offset = m_physSlice.offset();
+      result.length = m_physSlice.length();
+      result.mapPtr = m_physSlice.mapPtr(0);
+      return result;
+    }
+
+    /**
+     * \brief Retrieves sub slice handle
+     * 
+     * \param [in] offset Offset into buffer
+     * \param [in] length Sub slice length
+     * \returns Buffer slice handle
+     */
+    DxvkBufferSliceHandle getSliceHandle(VkDeviceSize offset, VkDeviceSize length) const {
+      DxvkBufferSliceHandle result;
+      result.handle = m_physSlice.handle();
+      result.offset = m_physSlice.offset() + offset;
+      result.length = length;
+      result.mapPtr = m_physSlice.mapPtr(offset);
+      return result;
+    }
+
     /**
      * \brief Retrieves descriptor info
      * 
      * \param [in] offset Buffer slice offset
      * \param [in] length Buffer slice length
-     * \param [in] keepOffset \c false to zero offset
      * \returns Buffer slice descriptor
      */
     DxvkDescriptorInfo getDescriptor(VkDeviceSize offset, VkDeviceSize length) const {
@@ -287,6 +330,31 @@ namespace dxvk {
       return m_buffer != nullptr;
     }
     
+    /**
+     * \brief Retrieves buffer slice handle
+     * 
+     * Returns the buffer handle and offset
+     * \returns Buffer slice handle
+     */
+    DxvkBufferSliceHandle getSliceHandle() const {
+      return m_buffer != nullptr
+        ? m_buffer->getSliceHandle(m_offset, m_length)
+        : DxvkBufferSliceHandle();
+    }
+
+    /**
+     * \brief Retrieves sub slice handle
+     * 
+     * \param [in] offset Offset into buffer
+     * \param [in] length Sub slice length
+     * \returns Buffer slice handle
+     */
+    DxvkBufferSliceHandle getSliceHandle(VkDeviceSize offset, VkDeviceSize length) const {
+      return m_buffer != nullptr
+        ? m_buffer->getSliceHandle(m_offset + offset, length)
+        : DxvkBufferSliceHandle();
+    }
+
     /**
      * \brief Physical slice
      * 
@@ -441,6 +509,16 @@ namespace dxvk {
       return m_physView->bufferResource();
     }
 
+    /**
+     * \brief Retrieves buffer slice handle
+     * \returns Buffer slice handle
+     */
+    DxvkBufferSliceHandle getSliceHandle() const {
+      return m_buffer->getSliceHandle(
+        m_info.rangeOffset,
+        m_info.rangeLength);
+    }
+    
     /**
      * \brief Underlying buffer slice
      * \returns Slice backing the view