1 files changed, 98 insertions, 0 deletions
diff --git a/src/mesa/pipe/pipebuffer/pb_buffer_null.c b/src/mesa/pipe/pipebuffer/pb_buffer_null.c
new file mode 100644
index 0000000000..a356c6b2d5
--- /dev/null
+++ b/src/mesa/pipe/pipebuffer/pb_buffer_null.c
@@ -0,0 +1,98 @@
+/**************************************************************************
+ *
+ * Copyright 2007 Tungsten Graphics, Inc., Cedar Park, Texas.
+ * All Rights Reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sub license, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the
+ * next paragraph) shall be included in all copies or substantial portions
+ * of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+ * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.
+ * IN NO EVENT SHALL TUNGSTEN GRAPHICS AND/OR ITS SUPPLIERS BE LIABLE FOR
+ * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+ * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+ * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ *
+ **************************************************************************/
+
+/**
+ * \file
+ * Null buffer implementation.
+ * 
+ * We have a special null buffer object so that we can safely call buffer 
+ * operations without having to check whether the buffer pointer is null or not.
+ * 
+ * \author José Fonseca <jrfonseca@tungstengraphics.com>
+ */
+
+
+#include "pipe/p_winsys.h"
+#include "pipe/p_defines.h"
+
+#include "pb_buffer.h"
+
+
+static void
+null_buffer_reference(struct pipe_buffer *buf)
+{
+   /* No-op */
+}
+
+
+static void
+null_buffer_release(struct pipe_buffer *buf)
+{
+   /* No-op */
+}
+
+
+static void *
+null_buffer_map(struct pipe_buffer *buf, 
+                unsigned flags)
+{
+   assert(0);
+   return NULL;
+}
+
+
+static void
+null_buffer_unmap(struct pipe_buffer *buf)
+{
+   assert(0);
+}
+
+
+static void
+null_buffer_get_base_buffer(struct pipe_buffer *buf,
+                            struct pipe_buffer **base_buf,
+                            unsigned *offset)
+{
+   *base_buf = buf;
+   *offset = 0;
+}
+
+
+const struct pipe_buffer_vtbl 
+pipe_buffer_vtbl = {
+      null_buffer_reference,
+      null_buffer_release,
+      null_buffer_map,
+      null_buffer_unmap,
+      null_buffer_get_base_buffer
+};
+
+
+struct pipe_buffer
+null_buffer = {
+      &pipe_buffer_vtbl
+};