First pass at a fallback concept for pipe devices.

Creates a new pipe driver that feeds commands to either a hardware or
software pipe depending on fallback state.

Untested concept checkpoint.  At this point it compiles.

6 files changed, 752 insertions, 0 deletions

diff --git a/src/mesa/pipe/failover/Makefile b/src/mesa/pipe/failover/Makefile
new file mode 100644
index 00000000000..72d0895c74d
--- /dev/null
+++ b/src/mesa/pipe/failover/Makefile
@@ -0,0 +1,21 @@
+
+TOP = ../../../..
+include $(TOP)/configs/current
+
+LIBNAME = failover
+
+DRIVER_SOURCES = \
+	fo_state.c \
+	fo_state_emit.c \
+	fo_context.c 
+
+C_SOURCES = \
+	$(COMMON_SOURCES) \
+	$(DRIVER_SOURCES)
+
+ASM_SOURCES = 
+
+include ../Makefile.template
+
+symlinks:
+
diff --git a/src/mesa/pipe/failover/fo_context.c b/src/mesa/pipe/failover/fo_context.c
new file mode 100644
index 00000000000..b88f1b466cb
--- /dev/null
+++ b/src/mesa/pipe/failover/fo_context.c
@@ -0,0 +1,155 @@
+/**************************************************************************
+ * 
+ * Copyright 2003 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.
+ * 
+ **************************************************************************/
+
+
+#include "pipe/p_defines.h"
+#include "pipe/p_winsys.h"
+#include "pipe/p_util.h"
+#include "pipe/p_context.h"
+
+#include "fo_context.h"
+#include "fo_winsys.h"
+
+
+
+static void failover_destroy( struct pipe_context *pipe )
+{
+   struct failover_context *failover = failover_context( pipe );
+
+   free( failover );
+}
+
+
+
+static boolean failover_draw_elements( struct pipe_context *pipe,
+				       struct pipe_buffer_handle *indexBuffer,
+				       unsigned indexSize,
+				       unsigned prim, unsigned start, unsigned count)
+{
+   struct failover_context *failover = failover_context( pipe );
+
+   /* If there has been any statechange since last time, try hardware
+    * rendering again:
+    */
+   if (failover->dirty) {
+      failover->mode = FO_HW;
+   }
+
+   /* Try hardware:
+    */
+   if (failover->mode == FO_HW) {
+      if (!failover->hw->draw_elements( failover->hw, 
+					indexBuffer, 
+					indexSize, 
+					prim, 
+					start, 
+					count )) {
+
+	 failover->hw->flush( failover->hw, ~0 );
+	 failover->mode = FO_SW;
+      }
+   }
+
+   /* Possibly try software:
+    */
+   if (failover->mode == FO_SW) {
+
+      if (failover->dirty) 
+	 failover_state_emit( failover );
+
+      failover->sw->draw_elements( failover->sw, 
+				   indexBuffer, 
+				   indexSize, 
+				   prim, 
+				   start, 
+				   count );
+
+      /* Be ready to switch back to hardware rendering without an
+       * intervening flush.  Unlikely to be much performance impact to
+       * this:
+       */
+      failover->sw->flush( failover->sw, ~0 );
+   }
+
+   return TRUE;
+}
+
+
+static boolean failover_draw_arrays( struct pipe_context *pipe,
+				     unsigned prim, unsigned start, unsigned count)
+{
+   return failover_draw_elements(pipe, NULL, 0, prim, start, count);
+}
+
+
+
+struct pipe_context *failover_create( struct pipe_context *hw,
+				      struct pipe_context *sw )
+{
+   struct failover_context *failover = CALLOC_STRUCT(failover_context);
+   if (failover == NULL)
+      return NULL;
+
+   failover->pipe.winsys = hw->winsys;
+   failover->pipe.destroy = failover_destroy;
+   failover->pipe.supported_formats = hw->supported_formats;
+   failover->pipe.max_texture_size = hw->max_texture_size;
+   failover->pipe.get_name = hw->get_name;
+   failover->pipe.get_vendor = hw->get_vendor;
+
+   failover->pipe.draw_arrays = failover_draw_arrays;
+   failover->pipe.draw_elements = failover_draw_elements;
+   failover->pipe.clear = hw->clear;
+
+   /* No software occlusion fallback (or other optional functionality)
+    * at this point - if the hardware doesn't support it, don't
+    * advertise it to the application.
+    */
+   failover->pipe.reset_occlusion_counter = hw->reset_occlusion_counter;
+   failover->pipe.get_occlusion_counter = hw->get_occlusion_counter;
+
+   failover_init_state_functions( failover );
+
+   failover->pipe.surface_alloc = hw->surface_alloc;
+   failover->pipe.get_tex_surface = hw->get_tex_surface;
+
+   failover->pipe.region_alloc = hw->region_alloc;
+   failover->pipe.region_release = hw->region_release;
+   failover->pipe.region_idle = hw->region_idle;
+   failover->pipe.region_map = hw->region_map;
+   failover->pipe.region_unmap = hw->region_unmap;
+   failover->pipe.region_data = hw->region_data;
+   failover->pipe.region_copy = hw->region_copy;
+   failover->pipe.region_fill = hw->region_fill;
+   failover->pipe.mipmap_tree_layout = hw->mipmap_tree_layout;
+   failover->pipe.flush = hw->flush;
+
+   failover->dirty = 0;
+
+   return &failover->pipe;
+}
+
diff --git a/src/mesa/pipe/failover/fo_context.h b/src/mesa/pipe/failover/fo_context.h
new file mode 100644
index 00000000000..5666d4e8306
--- /dev/null
+++ b/src/mesa/pipe/failover/fo_context.h
@@ -0,0 +1,113 @@
+/**************************************************************************
+ * 
+ * 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.
+ * 
+ **************************************************************************/
+
+/* Authors:  Keith Whitwell <[email protected]>
+ */
+
+#ifndef FO_CONTEXT_H
+#define FO_CONTEXT_H
+
+#include "pipe/p_state.h"
+#include "pipe/p_context.h"
+
+
+
+#define FO_NEW_VIEWPORT      0x1
+#define FO_NEW_SETUP         0x2
+#define FO_NEW_FRAGMENT_SHADER            0x4
+#define FO_NEW_BLEND         0x8
+#define FO_NEW_CLIP         0x10
+#define FO_NEW_SCISSOR      0x20
+#define FO_NEW_STIPPLE      0x40
+#define FO_NEW_FRAMEBUFFER  0x80
+#define FO_NEW_ALPHA_TEST  0x100
+#define FO_NEW_DEPTH_TEST  0x200
+#define FO_NEW_SAMPLER     0x400
+#define FO_NEW_TEXTURE     0x800
+#define FO_NEW_STENCIL    0x1000
+#define FO_NEW_VERTEX     0x2000
+#define FO_NEW_VERTEX_SHADER        0x4000
+#define FO_NEW_BLEND_COLOR    0x8000
+#define FO_NEW_CLEAR_COLOR    0x10000
+#define FO_NEW_VERTEX_BUFFER  0x20000
+#define FO_NEW_VERTEX_ELEMENT 0x40000
+
+
+
+#define FO_HW 0
+#define FO_SW 1
+
+struct failover_context {     
+   struct pipe_context pipe;  /**< base class */
+
+
+   /* The most recent drawing state as set by the driver:
+    */
+   struct pipe_alpha_test_state alpha_test;
+   struct pipe_blend_state blend;
+   struct pipe_blend_color blend_color;
+   struct pipe_clear_color_state clear_color;
+   struct pipe_clip_state clip;
+   struct pipe_depth_state depth_test;
+   struct pipe_framebuffer_state framebuffer;
+   struct pipe_shader_state fragment_shader;
+   struct pipe_shader_state vertex_shader;
+   struct pipe_poly_stipple poly_stipple;
+   struct pipe_scissor_state scissor;
+   struct pipe_sampler_state sampler[PIPE_MAX_SAMPLERS];
+   struct pipe_setup_state setup;
+   struct pipe_stencil_state stencil;
+   struct pipe_mipmap_tree *texture[PIPE_MAX_SAMPLERS];
+   struct pipe_viewport_state viewport;
+   struct pipe_vertex_buffer vertex_buffer[PIPE_ATTRIB_MAX];
+   struct pipe_vertex_element vertex_element[PIPE_ATTRIB_MAX];
+
+   unsigned dirty;
+   unsigned dirty_sampler;
+   unsigned dirty_texture;
+   unsigned dirty_vertex_buffer;
+   unsigned dirty_vertex_element;
+
+
+   unsigned mode;
+   struct pipe_context *hw;
+   struct pipe_context *sw;
+};
+
+
+
+void failover_init_state_functions( struct failover_context *failover );
+void failover_state_emit( struct failover_context *failover );
+
+static INLINE struct failover_context *
+failover_context( struct pipe_context *pipe )
+{
+   return (struct failover_context *)pipe;
+}
+
+
+#endif /* FO_CONTEXT_H */
diff --git a/src/mesa/pipe/failover/fo_state.c b/src/mesa/pipe/failover/fo_state.c
new file mode 100644
index 00000000000..097acf7d579
--- /dev/null
+++ b/src/mesa/pipe/failover/fo_state.c
@@ -0,0 +1,287 @@
+/**************************************************************************
+ * 
+ * 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.
+ * 
+ **************************************************************************/
+
+/* Authors:  Keith Whitwell <[email protected]>
+ */
+
+#include "fo_context.h"
+
+
+/* This looks like a lot of work at the moment - we're keeping a
+ * duplicate copy of the state up-to-date.  
+ *
+ * This can change in two ways:
+ * - With constant state objects we would only need to save a pointer,
+ *     not the whole object.
+ * - By adding a callback in the state tracker to re-emit state.  The
+ *     state tracker knows the current state already and can re-emit it 
+ *     without additional complexity.
+ *
+ * This works as a proof-of-concept, but a final version will have
+ * lower overheads.
+ */
+
+static void
+failover_set_alpha_test_state(struct pipe_context *pipe,
+                              const struct pipe_alpha_test_state *alpha)
+{
+   struct failover_context *failover = failover_context(pipe);
+
+   failover->alpha_test = *alpha;
+   failover->dirty |= FO_NEW_ALPHA_TEST;
+   failover->hw->set_alpha_test_state( failover->hw, alpha );
+}
+
+
+static void 
+failover_set_blend_state( struct pipe_context *pipe,
+			  const struct pipe_blend_state *blend )
+{
+   struct failover_context *failover = failover_context(pipe);
+
+   failover->blend = *blend;
+   failover->dirty |= FO_NEW_BLEND;
+   failover->hw->set_blend_state( failover->hw, blend );
+}
+
+
+static void 
+failover_set_blend_color( struct pipe_context *pipe,
+			  const struct pipe_blend_color *blend_color )
+{
+   struct failover_context *failover = failover_context(pipe);
+
+   failover->blend_color = *blend_color;
+   failover->dirty |= FO_NEW_BLEND_COLOR;
+   failover->hw->set_blend_color( failover->hw, blend_color );
+}
+
+static void 
+failover_set_clip_state( struct pipe_context *pipe,
+			 const struct pipe_clip_state *clip )
+{
+   struct failover_context *failover = failover_context(pipe);
+
+   failover->clip = *clip;
+   failover->dirty |= FO_NEW_CLIP;
+   failover->hw->set_clip_state( failover->hw, clip );
+}
+
+static void 
+failover_set_clear_color_state( struct pipe_context *pipe,
+				const struct pipe_clear_color_state *clear_color )
+{
+   struct failover_context *failover = failover_context(pipe);
+
+   failover->clear_color = *clear_color;
+   failover->dirty |= FO_NEW_CLEAR_COLOR;
+   failover->hw->set_clear_color_state( failover->hw, clear_color );
+}
+
+static void
+failover_set_depth_test_state(struct pipe_context *pipe,
+                              const struct pipe_depth_state *depth)
+{
+   struct failover_context *failover = failover_context(pipe);
+
+   failover->depth_test = *depth;
+   failover->dirty |= FO_NEW_DEPTH_TEST;
+   failover->hw->set_depth_state( failover->hw, depth );
+}
+
+static void
+failover_set_framebuffer_state(struct pipe_context *pipe,
+			       const struct pipe_framebuffer_state *framebuffer)
+{
+   struct failover_context *failover = failover_context(pipe);
+
+   failover->framebuffer = *framebuffer;
+   failover->dirty |= FO_NEW_FRAMEBUFFER;
+   failover->hw->set_framebuffer_state( failover->hw, framebuffer );
+}
+
+static void
+failover_set_fs_state(struct pipe_context *pipe,
+		      const struct pipe_shader_state *fs)
+{
+   struct failover_context *failover = failover_context(pipe);
+
+   failover->fragment_shader = *fs;
+   failover->dirty |= FO_NEW_FRAGMENT_SHADER;
+   failover->hw->set_fs_state( failover->hw, fs );
+}
+
+static void
+failover_set_vs_state(struct pipe_context *pipe,
+		      const struct pipe_shader_state *vs)
+{
+   struct failover_context *failover = failover_context(pipe);
+
+   failover->vertex_shader = *vs;
+   failover->dirty |= FO_NEW_VERTEX_SHADER;
+   failover->hw->set_vs_state( failover->hw, vs );
+}
+
+
+static void 
+failover_set_polygon_stipple( struct pipe_context *pipe,
+			      const struct pipe_poly_stipple *stipple )
+{
+   struct failover_context *failover = failover_context(pipe);
+
+   failover->poly_stipple = *stipple;
+   failover->dirty |= FO_NEW_STIPPLE;
+   failover->hw->set_polygon_stipple( failover->hw, stipple );
+}
+
+
+
+static void 
+failover_set_setup_state( struct pipe_context *pipe,
+			     const struct pipe_setup_state *setup )
+{
+   struct failover_context *failover = failover_context(pipe);
+
+   failover->setup = *setup; 
+   failover->dirty |= FO_NEW_SETUP;
+   failover->hw->set_setup_state( failover->hw, setup );
+}
+
+
+static void 
+failover_set_scissor_state( struct pipe_context *pipe,
+                                 const struct pipe_scissor_state *scissor )
+{
+   struct failover_context *failover = failover_context(pipe);
+
+   failover->scissor = *scissor;
+   failover->dirty |= FO_NEW_SCISSOR;
+   failover->hw->set_scissor_state( failover->hw, scissor );
+}
+
+static void
+failover_set_stencil_state(struct pipe_context *pipe,
+                           const struct pipe_stencil_state *stencil)
+{
+   struct failover_context *failover = failover_context(pipe);
+
+   failover->stencil = *stencil;
+   failover->dirty |= FO_NEW_STENCIL;
+   failover->hw->set_stencil_state( failover->hw, stencil );
+}
+
+
+static void
+failover_set_sampler_state(struct pipe_context *pipe,
+			   unsigned unit,
+                           const struct pipe_sampler_state *sampler)
+{
+   struct failover_context *failover = failover_context(pipe);
+
+   failover->sampler[unit] = *sampler;
+   failover->dirty |= FO_NEW_SAMPLER;
+   failover->dirty_sampler |= (1<<unit);
+   failover->hw->set_sampler_state( failover->hw, unit, sampler );
+}
+
+
+static void
+failover_set_texture_state(struct pipe_context *pipe,
+			   unsigned unit,
+                           struct pipe_mipmap_tree *texture)
+{
+   struct failover_context *failover = failover_context(pipe);
+
+   failover->texture[unit] = texture;
+   failover->dirty |= FO_NEW_TEXTURE;
+   failover->dirty_texture |= (1<<unit);
+   failover->hw->set_texture_state( failover->hw, unit, texture );
+}
+
+
+static void 
+failover_set_viewport_state( struct pipe_context *pipe,
+			     const struct pipe_viewport_state *viewport )
+{
+   struct failover_context *failover = failover_context(pipe);
+
+   failover->viewport = *viewport; 
+   failover->dirty |= FO_NEW_VIEWPORT;
+   failover->hw->set_viewport_state( failover->hw, viewport );
+}
+
+
+static void
+failover_set_vertex_buffer(struct pipe_context *pipe,
+			   unsigned unit,
+                           const struct pipe_vertex_buffer *vertex_buffer)
+{
+   struct failover_context *failover = failover_context(pipe);
+
+   failover->vertex_buffer[unit] = *vertex_buffer;
+   failover->dirty |= FO_NEW_VERTEX_BUFFER;
+   failover->dirty_vertex_buffer |= (1<<unit);
+   failover->hw->set_vertex_buffer( failover->hw, unit, vertex_buffer );
+}
+
+
+static void
+failover_set_vertex_element(struct pipe_context *pipe,
+			    unsigned unit,
+			    const struct pipe_vertex_element *vertex_element)
+{
+   struct failover_context *failover = failover_context(pipe);
+
+   failover->vertex_element[unit] = *vertex_element;
+   failover->dirty |= FO_NEW_VERTEX_ELEMENT;
+   failover->dirty_vertex_element |= (1<<unit);
+   failover->hw->set_vertex_element( failover->hw, unit, vertex_element );
+}
+
+
+void
+failover_init_state_functions( struct failover_context *failover )
+{
+   failover->pipe.set_alpha_test_state = failover_set_alpha_test_state;
+   failover->pipe.set_blend_color = failover_set_blend_color;
+   failover->pipe.set_blend_state = failover_set_blend_state;
+   failover->pipe.set_clip_state = failover_set_clip_state;
+   failover->pipe.set_clear_color_state = failover_set_clear_color_state;
+   failover->pipe.set_depth_state = failover_set_depth_test_state;
+   failover->pipe.set_framebuffer_state = failover_set_framebuffer_state;
+   failover->pipe.set_fs_state = failover_set_fs_state;
+   failover->pipe.set_vs_state = failover_set_vs_state;
+   failover->pipe.set_polygon_stipple = failover_set_polygon_stipple;
+   failover->pipe.set_sampler_state = failover_set_sampler_state;
+   failover->pipe.set_scissor_state = failover_set_scissor_state;
+   failover->pipe.set_setup_state = failover_set_setup_state;
+   failover->pipe.set_stencil_state = failover_set_stencil_state;
+   failover->pipe.set_texture_state = failover_set_texture_state;
+   failover->pipe.set_viewport_state = failover_set_viewport_state;
+   failover->pipe.set_vertex_buffer = failover_set_vertex_buffer;
+   failover->pipe.set_vertex_element = failover_set_vertex_element;
+}
diff --git a/src/mesa/pipe/failover/fo_state_emit.c b/src/mesa/pipe/failover/fo_state_emit.c
new file mode 100644
index 00000000000..66142882978
--- /dev/null
+++ b/src/mesa/pipe/failover/fo_state_emit.c
@@ -0,0 +1,131 @@
+/**************************************************************************
+ * 
+ * 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.
+ * 
+ **************************************************************************/
+
+/* Authors:  Keith Whitwell <[email protected]>
+ */
+
+#include "fo_context.h"
+
+/* This looks like a lot of work at the moment - we're keeping a
+ * duplicate copy of the state up-to-date.  
+ *
+ * This can change in two ways:
+ * - With constant state objects we would only need to save a pointer,
+ *     not the whole object.
+ * - By adding a callback in the state tracker to re-emit state.  The
+ *     state tracker knows the current state already and can re-emit it 
+ *     without additional complexity.
+ *
+ * This works as a proof-of-concept, but a final version will have
+ * lower overheads.
+ */
+
+void
+failover_state_emit( struct failover_context *failover )
+{
+   unsigned i;
+
+   if (failover->dirty & FO_NEW_ALPHA_TEST)
+      failover->hw->set_alpha_test_state( failover->hw, &failover->alpha_test );
+
+   if (failover->dirty & FO_NEW_BLEND)
+      failover->hw->set_blend_state( failover->hw, &failover->blend );
+
+   if (failover->dirty & FO_NEW_BLEND_COLOR)
+      failover->hw->set_blend_color( failover->hw, &failover->blend_color );
+
+   if (failover->dirty & FO_NEW_CLIP)
+      failover->hw->set_clip_state( failover->hw, &failover->clip );
+
+   if (failover->dirty & FO_NEW_CLEAR_COLOR)
+      failover->hw->set_clear_color_state( failover->hw, &failover->clear_color );
+
+   if (failover->dirty & FO_NEW_DEPTH_TEST)
+      failover->hw->set_depth_state( failover->hw, &failover->depth_test );
+
+   if (failover->dirty & FO_NEW_FRAMEBUFFER)
+      failover->hw->set_framebuffer_state( failover->hw, &failover->framebuffer );
+
+   if (failover->dirty & FO_NEW_FRAGMENT_SHADER)
+      failover->hw->set_fs_state( failover->hw, &failover->fragment_shader );
+
+   if (failover->dirty & FO_NEW_VERTEX_SHADER)
+      failover->hw->set_vs_state( failover->hw, &failover->vertex_shader );
+
+   if (failover->dirty & FO_NEW_STIPPLE)
+      failover->hw->set_polygon_stipple( failover->hw, &failover->poly_stipple );
+
+   if (failover->dirty & FO_NEW_SETUP)
+      failover->hw->set_setup_state( failover->hw, &failover->setup );
+
+   if (failover->dirty & FO_NEW_SCISSOR)
+      failover->hw->set_scissor_state( failover->hw, &failover->scissor );
+
+   if (failover->dirty & FO_NEW_STENCIL)
+      failover->hw->set_stencil_state( failover->hw, &failover->stencil );
+
+   if (failover->dirty & FO_NEW_VIEWPORT)
+      failover->hw->set_viewport_state( failover->hw, &failover->viewport );
+
+   if (failover->dirty & FO_NEW_SAMPLER) {
+      for (i = 0; i < PIPE_MAX_SAMPLERS; i++) {
+	 if (failover->dirty_sampler & (1<<i)) {
+	    failover->hw->set_sampler_state( failover->hw, i, 
+					     &failover->sampler[i] );
+	 }
+      }
+   }
+
+   if (failover->dirty & FO_NEW_TEXTURE) {
+      for (i = 0; i < PIPE_MAX_SAMPLERS; i++) {
+	 if (failover->dirty_texture & (1<<i)) {
+	    failover->hw->set_texture_state( failover->hw, i, 
+					     failover->texture[i] );
+	 }
+      }
+   }
+
+   if (failover->dirty & FO_NEW_VERTEX_BUFFER) {
+      for (i = 0; i < PIPE_ATTRIB_MAX; i++) {
+	 if (failover->dirty_vertex_buffer & (1<<i)) {
+	    failover->hw->set_vertex_buffer( failover->hw, i, 
+					     &failover->vertex_buffer[i] );
+	 }
+      }
+   }
+
+   if (failover->dirty & FO_NEW_VERTEX_ELEMENT) {
+      for (i = 0; i < PIPE_ATTRIB_MAX; i++) {
+	 if (failover->dirty_vertex_element & (1<<i)) {
+	    failover->hw->set_vertex_element( failover->hw, i, 
+					      &failover->vertex_element[i] );
+	 }
+      }
+   }
+
+   failover->dirty = 0;
+}
diff --git a/src/mesa/pipe/failover/fo_winsys.h b/src/mesa/pipe/failover/fo_winsys.h
new file mode 100644
index 00000000000..a8ce997a1f6
--- /dev/null
+++ b/src/mesa/pipe/failover/fo_winsys.h
@@ -0,0 +1,45 @@
+/**************************************************************************
+ * 
+ * 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.
+ * 
+ **************************************************************************/
+
+#ifndef FO_WINSYS_H
+#define FO_WINSYS_H
+
+
+/* This is the interface that failover requires any window system
+ * hosting it to implement.  This is the only include file in failover
+ * which is public.
+ */
+
+
+struct pipe_context;
+
+
+struct pipe_context *failover_create( struct pipe_context *hw,
+				      struct pipe_context *sw );
+
+
+#endif /* FO_WINSYS_H */