[D3D12] Experimental 2x resolution scale

src/xenia/gpu/texture_util.h

@@ -64,6 +64,13 @@ inline uint32_t GetSmallestMipLevel(uint32_t width, uint32_t height,
   return smallest_mip;
 }
 
+// Returns the total size of memory the texture uses starting from its base and
+// mip addresses, in bytes (both are optional).
+void GetTextureTotalSize(Dimension dimension, uint32_t width, uint32_t height,
+                         uint32_t depth, TextureFormat format, bool is_tiled,
+                         bool packed_mips, uint32_t mip_max_level,
+                         uint32_t* base_size, uint32_t* mip_size);
+
 int32_t GetTiledOffset2D(int32_t x, int32_t y, uint32_t width,
                          uint32_t log2_bpb);