gallium: give the screen priority when it comes to buffer allocations

allows the driver to overwrite buffer allocation, first step on the way
to making winsys interface internal to the drivers. state trackers and
the code above it will go through the screen

1 files changed, 68 insertions, 1 deletions

diff --git a/src/gallium/include/pipe/p_screen.h b/src/gallium/include/pipe/p_screen.h
index 492667c93a..b072484a84 100644
--- a/src/gallium/include/pipe/p_screen.h
+++ b/src/gallium/include/pipe/p_screen.h
@@ -128,7 +128,74 @@ struct pipe_screen {
 
    void (*surface_unmap)( struct pipe_screen *,
                           struct pipe_surface *surface );
-   
+
+
+   /**
+    * Buffer management. Buffer attributes are mostly fixed over its lifetime.
+    *
+    * 
+    */
+   struct pipe_buffer *(*buffer_create)( struct pipe_screen *screen,
+                                         unsigned alignment,
+                                         unsigned usage,
+                                         unsigned size );
+
+   /**
+    * Create a buffer that wraps user-space data.
+    *
+    * Effectively this schedules a delayed call to buffer_create
+    * followed by an upload of the data at *some point in the future*,
+    * or perhaps never.  Basically the allocate/upload is delayed
+    * until the buffer is actually passed to hardware.
+    *
+    * The intention is to provide a quick way to turn regular data
+    * into a buffer, and secondly to avoid a copy operation if that
+    * data subsequently turns out to be only accessed by the CPU.
+    *
+    * Common example is OpenGL vertex buffers that are subsequently
+    * processed either by software TNL in the driver or by passing to
+    * hardware.
+    *
+    * XXX: What happens if the delayed call to buffer_create() fails?
+    *
+    * Note that ptr may be accessed at any time upto the time when the
+    * buffer is destroyed, so the data must not be freed before then.
+    */
+   struct pipe_buffer *(*user_buffer_create)(struct pipe_screen *screen,
+                                             void *ptr,
+                                             unsigned bytes);
+
+   /**
+    * Allocate storage for a display target surface.
+    *
+    * Often surfaces which are meant to be blitted to the front screen (i.e.,
+    * display targets) must be allocated with special characteristics, memory
+    * pools, or obtained directly from the windowing system.
+    *
+    * This callback is invoked by the pipe_screenwhen creating a texture marked
+    * with the PIPE_TEXTURE_USAGE_DISPLAY_TARGET flag  to get the underlying
+    * buffer storage.
+    */
+   struct pipe_buffer *(*surface_buffer_create)(struct pipe_screen *screen,
+						unsigned width, unsigned height,
+						enum pipe_format format,
+						unsigned usage,
+						unsigned *stride);
+
+
+   /**
+    * Map the entire data store of a buffer object into the client's address.
+    * flags is bitmask of PIPE_BUFFER_USAGE_CPU_READ/WRITE flags.
+    */
+   void *(*buffer_map)( struct pipe_screen *screen,
+			struct pipe_buffer *buf,
+			unsigned usage );
+
+   void (*buffer_unmap)( struct pipe_screen *screen,
+			 struct pipe_buffer *buf );
+
+   void (*buffer_destroy)( struct pipe_screen *screen,
+			   struct pipe_buffer *buf );
 };