gallium: add start_slot parameter to set_vertex_buffers

This allows updating only a subrange of buffer bindings.

set_vertex_buffers(pipe, start_slot, count, NULL) unbinds buffers in that
range. Binding NULL resources unbinds buffers too (both buffer and user_buffer
must be NULL).

The meta ops are adapted to only save, change, and restore the single slot
they use. The cso_context can save and restore only one vertex buffer slot.
The clients can query which one it is using cso_get_aux_vertex_buffer_slot.
It's currently set to 0. (the Draw module breaks if it's set to non-zero)

It should decrease the CPU overhead when using a lot of meta ops, but
the drivers must be able to treat each vertex buffer slot as a separate
state (only r600g does so at the moment).

I can imagine this also being useful for optimizing some OpenGL use cases.

Reviewed-by: Brian Paul <[email protected]>

1 files changed, 90 insertions, 0 deletions

diff --git a/src/gallium/auxiliary/util/u_helpers.c b/src/gallium/auxiliary/util/u_helpers.c
new file mode 100644
index 00000000000..ac1edcdbb82
--- /dev/null
+++ b/src/gallium/auxiliary/util/u_helpers.c
@@ -0,0 +1,90 @@
+/**************************************************************************
+ *
+ * Copyright 2012 Marek Olšák <[email protected]>
+ * 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 THE AUTHORS AND/OR THEIR 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.
+ *
+ **************************************************************************/
+
+#include "util/u_helpers.h"
+#include "util/u_inlines.h"
+
+/**
+ * This function is used to copy an array of pipe_vertex_buffer structures,
+ * while properly referencing the pipe_vertex_buffer::buffer member.
+ *
+ * enabled_buffers is updated such that the bits corresponding to the indices
+ * of disabled buffers are set to 0 and the enabled ones are set to 1.
+ *
+ * \sa util_copy_framebuffer_state
+ */
+void util_set_vertex_buffers_mask(struct pipe_vertex_buffer *dst,
+                                  uint32_t *enabled_buffers,
+                                  const struct pipe_vertex_buffer *src,
+                                  unsigned start_slot, unsigned count)
+{
+   unsigned i;
+   uint32_t bitmask = 0;
+
+   dst += start_slot;
+
+   if (src) {
+      for (i = 0; i < count; i++) {
+         if (src[i].buffer || src[i].user_buffer) {
+            bitmask |= 1 << i;
+         }
+         pipe_resource_reference(&dst[i].buffer, src[i].buffer);
+      }
+
+      /* Copy over the other members of pipe_vertex_buffer. */
+      memcpy(dst, src, count * sizeof(struct pipe_vertex_buffer));
+
+      *enabled_buffers &= ~(((1ull << count) - 1) << start_slot);
+      *enabled_buffers |= bitmask << start_slot;
+   }
+   else {
+      /* Unreference the buffers. */
+      for (i = 0; i < count; i++) {
+         pipe_resource_reference(&dst[i].buffer, NULL);
+         dst[i].user_buffer = NULL;
+      }
+
+      *enabled_buffers &= ~(((1ull << count) - 1) << start_slot);
+   }
+}
+
+/**
+ * Same as util_set_vertex_buffers_mask, but it only returns the number
+ * of bound buffers.
+ */
+void util_set_vertex_buffers_count(struct pipe_vertex_buffer *dst,
+                                   unsigned *dst_count,
+                                   const struct pipe_vertex_buffer *src,
+                                   unsigned start_slot, unsigned count)
+{
+   uint32_t enabled_buffers = (1ull << *dst_count) - 1;
+
+   util_set_vertex_buffers_mask(dst, &enabled_buffers, src, start_slot,
+                                count);
+
+   *dst_count = util_last_bit(enabled_buffers);
+}