draw: Add vsplit frontend.

vsplit is based on varray.  It sets the split flags when a primitive is
splitted.  It also has support for indexed primitives.

For indexed primitives, unlike vcache, vsplit splits the primitives
instead of decomposes them.

6 files changed, 695 insertions, 1 deletions

diff --git a/src/gallium/auxiliary/Makefile b/src/gallium/auxiliary/Makefile
index 9544e90a96..ac3828c513 100644
--- a/src/gallium/auxiliary/Makefile
+++ b/src/gallium/auxiliary/Makefile
@@ -37,6 +37,7 @@ C_SOURCES = \
 	draw/draw_pt_util.c \
 	draw/draw_pt_varray.c \
 	draw/draw_pt_vcache.c \
+	draw/draw_pt_vsplit.c \
 	draw/draw_vertex.c \
 	draw/draw_vs.c \
 	draw/draw_vs_varient.c \
diff --git a/src/gallium/auxiliary/SConscript b/src/gallium/auxiliary/SConscript
index 3124e20ce8..89d1caf116 100644
--- a/src/gallium/auxiliary/SConscript
+++ b/src/gallium/auxiliary/SConscript
@@ -82,6 +82,7 @@ source = [
     'draw/draw_pt_util.c',
     'draw/draw_pt_varray.c',
     'draw/draw_pt_vcache.c',
+    'draw/draw_pt_vsplit.c',
     'draw/draw_vertex.c',
     'draw/draw_vs.c',
     'draw/draw_vs_aos.c',
diff --git a/src/gallium/auxiliary/draw/draw_pt.h b/src/gallium/auxiliary/draw/draw_pt.h
index 688b15c4fa..de3f638db5 100644
--- a/src/gallium/auxiliary/draw/draw_pt.h
+++ b/src/gallium/auxiliary/draw/draw_pt.h
@@ -52,8 +52,19 @@ struct draw_vertex_info;
 /* The "front end" - prepare sets of fetch, draw elements for the
  * middle end.
  *
- * Currenly one version of this:
+ * The fetch elements are indices to the vertices.  The draw elements are
+ * indices to the fetched vertices.  When both arrays of elements are both
+ * linear, middle->run_linear is called;  When only the fetch elements are
+ * linear, middle->run_linear_elts is called;  Otherwise, middle->run is
+ * called.
+ *
+ * When the number of the draw elements exceeds max_vertex of the middle end,
+ * the draw elements (as well as the fetch elements) are splitted and the
+ * middle end is called multiple times.
+ *
+ * Currenly there are:
  *    - vcache - catchall implementation, decomposes to TRI/LINE/POINT prims
+ *    - vsplit - catchall implementation, splits big prims
  * Later:
  *    - varray, varray_split
  *    - velement, velement_split
@@ -138,6 +149,7 @@ const void *draw_pt_elt_ptr( struct draw_context *draw,
  */
 struct draw_pt_front_end *draw_pt_vcache( struct draw_context *draw );
 struct draw_pt_front_end *draw_pt_varray(struct draw_context *draw);
+struct draw_pt_front_end *draw_pt_vsplit(struct draw_context *draw);
 
 
 /* Middle-ends:
diff --git a/src/gallium/auxiliary/draw/draw_pt_vsplit.c b/src/gallium/auxiliary/draw/draw_pt_vsplit.c
new file mode 100644
index 0000000000..a687525309
--- /dev/null
+++ b/src/gallium/auxiliary/draw/draw_pt_vsplit.c
@@ -0,0 +1,208 @@
+/*
+ * Mesa 3-D graphics library
+ * Version:  7.9
+ *
+ * Copyright 2007-2008 Tungsten Graphics, Inc., Cedar Park, Texas.
+ * Copyright (C) 2010 LunarG Inc.
+ *
+ * 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, sublicense,
+ * 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 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 NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS 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_math.h"
+#include "util/u_memory.h"
+
+#include "draw/draw_context.h"
+#include "draw/draw_private.h"
+#include "draw/draw_pt.h"
+
+#define SEGMENT_SIZE 1024
+#define MAP_SIZE     256
+
+struct vsplit_frontend {
+   struct draw_pt_front_end base;
+   struct draw_context *draw;
+
+   unsigned prim;
+
+   struct draw_pt_middle_end *middle;
+
+   unsigned max_vertices;
+   ushort segment_size;
+
+   /* buffers for splitting */
+   unsigned fetch_elts[SEGMENT_SIZE];
+   ushort draw_elts[SEGMENT_SIZE];
+   ushort identity_draw_elts[SEGMENT_SIZE];
+
+   struct {
+      /* map a fetch element to a draw element */
+      unsigned fetches[MAP_SIZE];
+      ushort draws[MAP_SIZE];
+      boolean has_max_fetch;
+
+      ushort num_fetch_elts;
+      ushort num_draw_elts;
+   } cache;
+};
+
+
+static void
+vsplit_clear_cache(struct vsplit_frontend *vsplit)
+{
+   memset(vsplit->cache.fetches, 0xff, sizeof(vsplit->cache.fetches));
+   vsplit->cache.has_max_fetch = FALSE;
+   vsplit->cache.num_fetch_elts = 0;
+   vsplit->cache.num_draw_elts = 0;
+}
+
+static void
+vsplit_flush_cache(struct vsplit_frontend *vsplit, unsigned flags)
+{
+   vsplit->middle->run(vsplit->middle,
+         vsplit->fetch_elts, vsplit->cache.num_fetch_elts,
+         vsplit->draw_elts, vsplit->cache.num_draw_elts, flags);
+}
+
+/**
+ * Add a fetch element and add it to the draw elements.
+ */
+static INLINE void
+vsplit_add_cache(struct vsplit_frontend *vsplit, unsigned fetch)
+{
+   unsigned hash = fetch % MAP_SIZE;
+
+   if (vsplit->cache.fetches[hash] != fetch) {
+      /* update cache */
+      vsplit->cache.fetches[hash] = fetch;
+      vsplit->cache.draws[hash] = vsplit->cache.num_fetch_elts;
+
+      /* add fetch */
+      assert(vsplit->cache.num_fetch_elts < vsplit->segment_size);
+      vsplit->fetch_elts[vsplit->cache.num_fetch_elts++] = fetch;
+   }
+
+   vsplit->draw_elts[vsplit->cache.num_draw_elts++] = vsplit->cache.draws[hash];
+}
+
+
+/**
+ * Add a fetch element and add it to the draw elements.  The fetch element is
+ * in full range (uint).
+ */
+static INLINE void
+vsplit_add_cache_uint(struct vsplit_frontend *vsplit, unsigned fetch)
+{
+   /* special care for 0xffffffff */
+   if (fetch == 0xffffffff && !vsplit->cache.has_max_fetch) {
+      unsigned hash = fetch % MAP_SIZE;
+      vsplit->cache.fetches[hash] = fetch - 1; /* force update */
+      vsplit->cache.has_max_fetch = TRUE;
+   }
+
+   vsplit_add_cache(vsplit, fetch);
+}
+
+
+#define FUNC vsplit_run_linear
+#include "draw_pt_vsplit_tmp.h"
+
+#define FUNC vsplit_run_ubyte
+#define ELT_TYPE ubyte
+#define ADD_CACHE(vsplit, fetch) vsplit_add_cache(vsplit, fetch)
+#include "draw_pt_vsplit_tmp.h"
+
+#define FUNC vsplit_run_ushort
+#define ELT_TYPE ushort
+#define ADD_CACHE(vsplit, fetch) vsplit_add_cache(vsplit, fetch)
+#include "draw_pt_vsplit_tmp.h"
+
+#define FUNC vsplit_run_uint
+#define ELT_TYPE uint
+#define ADD_CACHE(vsplit, fetch) vsplit_add_cache_uint(vsplit, fetch)
+#include "draw_pt_vsplit_tmp.h"
+
+
+static void vsplit_prepare(struct draw_pt_front_end *frontend,
+                           unsigned in_prim,
+                           struct draw_pt_middle_end *middle,
+                           unsigned opt)
+{
+   struct vsplit_frontend *vsplit = (struct vsplit_frontend *) frontend;
+
+   switch (vsplit->draw->pt.user.eltSize) {
+   case 0:
+      vsplit->base.run = vsplit_run_linear;
+      break;
+   case 1:
+      vsplit->base.run = vsplit_run_ubyte;
+      break;
+   case 2:
+      vsplit->base.run = vsplit_run_ushort;
+      break;
+   case 4:
+      vsplit->base.run = vsplit_run_uint;
+      break;
+   default:
+      assert(0);
+      break;
+   }
+
+   /* split only */
+   vsplit->prim = in_prim;
+
+   vsplit->middle = middle;
+   middle->prepare(middle, vsplit->prim, opt, &vsplit->max_vertices);
+
+   vsplit->segment_size = MIN2(SEGMENT_SIZE, vsplit->max_vertices);
+}
+
+
+static void vsplit_finish(struct draw_pt_front_end *frontend)
+{
+   struct vsplit_frontend *vsplit = (struct vsplit_frontend *) frontend;
+   vsplit->middle->finish(vsplit->middle);
+   vsplit->middle = NULL;
+}
+
+
+static void vsplit_destroy(struct draw_pt_front_end *frontend)
+{
+   FREE(frontend);
+}
+
+
+struct draw_pt_front_end *draw_pt_vsplit(struct draw_context *draw)
+{
+   struct vsplit_frontend *vsplit = CALLOC_STRUCT(vsplit_frontend);
+   ushort i;
+
+   if (!vsplit)
+      return NULL;
+
+   vsplit->base.prepare = vsplit_prepare;
+   vsplit->base.run     = NULL;
+   vsplit->base.finish  = vsplit_finish;
+   vsplit->base.destroy = vsplit_destroy;
+   vsplit->draw = draw;
+
+   for (i = 0; i < SEGMENT_SIZE; i++)
+      vsplit->identity_draw_elts[i] = i;
+
+   return &vsplit->base;
+}
diff --git a/src/gallium/auxiliary/draw/draw_pt_vsplit_tmp.h b/src/gallium/auxiliary/draw/draw_pt_vsplit_tmp.h
new file mode 100644
index 0000000000..efeaa56711
--- /dev/null
+++ b/src/gallium/auxiliary/draw/draw_pt_vsplit_tmp.h
@@ -0,0 +1,301 @@
+/*
+ * Mesa 3-D graphics library
+ * Version:  7.9
+ *
+ * Copyright 2007-2008 Tungsten Graphics, Inc., Cedar Park, Texas.
+ * Copyright (C) 2010 LunarG Inc.
+ *
+ * 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, sublicense,
+ * 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 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 NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS 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.
+ */
+
+#define CONCAT2(name, elt_type) name ## elt_type
+#define CONCAT(name, elt_type) CONCAT2(name, elt_type)
+
+#ifdef ELT_TYPE
+
+/**
+ * Fetch all elements in [min_index, max_index] with bias, and use the
+ * (rebased) index buffer as the draw elements.
+ */
+static boolean
+CONCAT(vsplit_segment_fast_, ELT_TYPE)(struct vsplit_frontend *vsplit,
+                                       unsigned flags,
+                                       unsigned istart, unsigned icount)
+{
+   struct draw_context *draw = vsplit->draw;
+   const ELT_TYPE *ib = (const ELT_TYPE *) draw->pt.user.elts;
+   const unsigned min_index = draw->pt.user.min_index;
+   const unsigned max_index = draw->pt.user.max_index;
+   const int elt_bias = draw->pt.user.eltBias;
+   unsigned fetch_start, fetch_count;
+   const ushort *draw_elts;
+   unsigned i;
+
+   assert(icount <= vsplit->segment_size);
+
+   /* this is faster only when we fetch less elements than the normal path */
+   if (max_index - min_index > icount - 1)
+      return FALSE;
+
+   if (elt_bias < 0 && min_index < -elt_bias)
+      return FALSE;
+
+   /* why this check? */
+   for (i = 0; i < draw->pt.nr_vertex_elements; i++) {
+      if (draw->pt.vertex_element[i].instance_divisor)
+         return FALSE;
+   }
+
+   fetch_start = min_index + elt_bias;
+   fetch_count = max_index - min_index + 1;
+
+   if (min_index == 0 && sizeof(ib[0]) == sizeof(draw_elts[0])) {
+      for (i = 0; i < icount; i++) {
+         ELT_TYPE idx = ib[istart + i];
+         assert(idx >= min_index && idx <= max_index);
+      }
+      draw_elts = (const ushort *) ib;
+   }
+   else {
+      if (min_index == 0) {
+         for (i = 0; i < icount; i++) {
+            ELT_TYPE idx = ib[istart + i];
+
+            assert(idx >= min_index && idx <= max_index);
+            vsplit->draw_elts[i] = (ushort) idx;
+         }
+      }
+      else {
+         for (i = 0; i < icount; i++) {
+            ELT_TYPE idx = ib[istart + i];
+
+            assert(idx >= min_index && idx <= max_index);
+            vsplit->draw_elts[i] = (ushort) (idx - min_index);
+         }
+      }
+
+      draw_elts = vsplit->draw_elts;
+   }
+
+   return vsplit->middle->run_linear_elts(vsplit->middle,
+                                          fetch_start, fetch_count,
+                                          draw_elts, icount, flags);
+}
+
+/**
+ * Use the cache to prepare the fetch and draw elements, and flush.
+ *
+ * When spoken is TRUE, ispoken replaces istart;  When close is TRUE, iclose is
+ * appended.
+ */
+static INLINE void
+CONCAT(vsplit_segment_cache_, ELT_TYPE)(struct vsplit_frontend *vsplit,
+                                        unsigned flags,
+                                        unsigned istart, unsigned icount,
+                                        boolean spoken, unsigned ispoken,
+                                        boolean close, unsigned iclose)
+{
+   struct draw_context *draw = vsplit->draw;
+   const ELT_TYPE *ib = (const ELT_TYPE *) draw->pt.user.elts;
+   const int ibias = draw->pt.user.eltBias;
+   unsigned i;
+
+   assert(icount + !!close <= vsplit->segment_size);
+
+   vsplit_clear_cache(vsplit);
+
+   spoken = !!spoken;
+   if (ibias == 0) {
+      if (spoken)
+         ADD_CACHE(vsplit, ib[ispoken]);
+
+      for (i = spoken; i < icount; i++)
+         ADD_CACHE(vsplit, ib[istart + i]);
+
+      if (close)
+         ADD_CACHE(vsplit, ib[iclose]);
+   }
+   else if (ibias > 0) {
+      if (spoken)
+         ADD_CACHE(vsplit, (uint) ib[ispoken] + ibias);
+
+      for (i = spoken; i < icount; i++)
+         ADD_CACHE(vsplit, (uint) ib[istart + i] + ibias);
+
+      if (close)
+         ADD_CACHE(vsplit, (uint) ib[iclose] + ibias);
+   }
+   else {
+      if (spoken) {
+         if (ib[ispoken] < -ibias)
+            return;
+         ADD_CACHE(vsplit, ib[ispoken] + ibias);
+      }
+
+      for (i = spoken; i < icount; i++) {
+         if (ib[istart + i] < -ibias)
+            return;
+         ADD_CACHE(vsplit, ib[istart + i] + ibias);
+      }
+
+      if (close) {
+         if (ib[iclose] < -ibias)
+            return;
+         ADD_CACHE(vsplit, ib[iclose] + ibias);
+      }
+   }
+
+   vsplit_flush_cache(vsplit, flags);
+}
+
+static void
+CONCAT(vsplit_segment_simple_, ELT_TYPE)(struct vsplit_frontend *vsplit,
+                                         unsigned flags,
+                                         unsigned istart,
+                                         unsigned icount)
+{
+   /* the primitive is not splitted */
+   if (!(flags)) {
+      if (CONCAT(vsplit_segment_fast_, ELT_TYPE)(vsplit,
+               flags, istart, icount))
+         return;
+   }
+   CONCAT(vsplit_segment_cache_, ELT_TYPE)(vsplit,
+         flags, istart, icount, FALSE, 0, FALSE, 0);
+}
+
+static void
+CONCAT(vsplit_segment_loop_, ELT_TYPE)(struct vsplit_frontend *vsplit,
+                                       unsigned flags,
+                                       unsigned istart,
+                                       unsigned icount,
+                                       unsigned i0)
+{
+   const boolean close_loop = ((flags) == DRAW_SPLIT_BEFORE);
+
+   CONCAT(vsplit_segment_cache_, ELT_TYPE)(vsplit,
+         flags, istart, icount, FALSE, 0, close_loop, i0);
+}
+
+static void
+CONCAT(vsplit_segment_fan_, ELT_TYPE)(struct vsplit_frontend *vsplit,
+                                      unsigned flags,
+                                      unsigned istart,
+                                      unsigned icount,
+                                      unsigned i0)
+{
+   const boolean use_spoken = (((flags) & DRAW_SPLIT_BEFORE) != 0);
+
+   CONCAT(vsplit_segment_cache_, ELT_TYPE)(vsplit,
+         flags, istart, icount, use_spoken, i0, FALSE, 0);
+}
+
+#define LOCAL_VARS                                                         \
+   struct vsplit_frontend *vsplit = (struct vsplit_frontend *) frontend;   \
+   const unsigned prim = vsplit->prim;                                     \
+   const unsigned max_count_simple = vsplit->segment_size;                 \
+   const unsigned max_count_loop = vsplit->segment_size - 1;               \
+   const unsigned max_count_fan = vsplit->segment_size;
+
+#else /* ELT_TYPE */
+
+static void
+vsplit_segment_simple_linear(struct vsplit_frontend *vsplit, unsigned flags,
+                             unsigned istart, unsigned icount)
+{
+   assert(icount <= vsplit->max_vertices);
+   vsplit->middle->run_linear(vsplit->middle, istart, icount, flags);
+}
+
+static void
+vsplit_segment_loop_linear(struct vsplit_frontend *vsplit, unsigned flags,
+                           unsigned istart, unsigned icount, unsigned i0)
+{
+   boolean close_loop = (flags == DRAW_SPLIT_BEFORE);
+   unsigned nr;
+
+   assert(icount + !!close_loop <= vsplit->segment_size);
+
+   if (close_loop) {
+      for (nr = 0; nr < icount; nr++)
+         vsplit->fetch_elts[nr] = istart + nr;
+      vsplit->fetch_elts[nr++] = i0;
+
+      vsplit->middle->run(vsplit->middle, vsplit->fetch_elts, nr,
+            vsplit->identity_draw_elts, nr, flags);
+   }
+   else {
+      vsplit->middle->run_linear(vsplit->middle, istart, icount, flags);
+   }
+}
+
+static void
+vsplit_segment_fan_linear(struct vsplit_frontend *vsplit, unsigned flags,
+                          unsigned istart, unsigned icount, unsigned i0)
+{
+   boolean use_spoken = ((flags & DRAW_SPLIT_BEFORE) != 0);
+   unsigned nr = 0, i;
+
+   assert(icount + !!use_spoken <= vsplit->segment_size);
+
+   if (use_spoken) {
+      vsplit->fetch_elts[nr++] = i0;
+      for (i = 1 ; i < icount; i++)
+         vsplit->fetch_elts[nr++] = istart + i;
+
+      vsplit->middle->run(vsplit->middle, vsplit->fetch_elts, nr,
+            vsplit->identity_draw_elts, nr, flags);
+   }
+   else {
+      vsplit->middle->run_linear(vsplit->middle, istart, icount, flags);
+   }
+}
+
+#define LOCAL_VARS                                                         \
+   struct vsplit_frontend *vsplit = (struct vsplit_frontend *) frontend;   \
+   const unsigned prim = vsplit->prim;                                     \
+   const unsigned max_count_simple = vsplit->max_vertices;                 \
+   const unsigned max_count_loop = vsplit->segment_size - 1;               \
+   const unsigned max_count_fan = vsplit->segment_size;
+
+#define ELT_TYPE linear
+
+#endif /* ELT_TYPE */
+
+#define FUNC_VARS                      \
+   struct draw_pt_front_end *frontend, \
+   unsigned start,                     \
+   unsigned count
+
+#define SEGMENT_SIMPLE(flags, istart, icount)   \
+   CONCAT(vsplit_segment_simple_, ELT_TYPE)(vsplit, flags, istart, icount)
+
+#define SEGMENT_LOOP(flags, istart, icount, i0) \
+   CONCAT(vsplit_segment_loop_, ELT_TYPE)(vsplit, flags, istart, icount, i0)
+
+#define SEGMENT_FAN(flags, istart, icount, i0)  \
+   CONCAT(vsplit_segment_fan_, ELT_TYPE)(vsplit, flags, istart, icount, i0)
+
+#include "draw_split_tmp.h"
+
+#undef CONCAT2
+#undef CONCAT
+
+#undef ELT_TYPE
+#undef ADD_CACHE
diff --git a/src/gallium/auxiliary/draw/draw_split_tmp.h b/src/gallium/auxiliary/draw/draw_split_tmp.h
new file mode 100644
index 0000000000..40ab0b71f1
--- /dev/null
+++ b/src/gallium/auxiliary/draw/draw_split_tmp.h
@@ -0,0 +1,171 @@
+/*
+ * Mesa 3-D graphics library
+ * Version:  7.9
+ *
+ * Copyright 2008 Tungsten Graphics, Inc., Cedar Park, Texas.
+ * Copyright (C) 2010 LunarG Inc.
+ *
+ * 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, sublicense,
+ * 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 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 NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS 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.
+ */
+
+static void
+FUNC(FUNC_VARS)
+{
+   unsigned first, incr;
+   LOCAL_VARS
+
+   /*
+    * prim, start, count, and max_count_{simple,loop,fan} should have been
+    * defined
+    */
+   if (0) {
+      debug_printf("%s: prim 0x%x, start %d, count %d, max_count_simple %d, "
+                   "max_count_loop %d, max_count_fan %d\n",
+                   __FUNCTION__, prim, start, count, max_count_simple,
+                   max_count_loop, max_count_fan);
+   }
+
+   draw_pt_split_prim(prim, &first, &incr);
+   /* sanitize primitive length */
+   count = draw_pt_trim_count(count, first, incr);
+   if (count < first)
+      return;
+
+   /* must be able to at least flush two complete primitives */
+   assert(max_count_simple >= first + incr &&
+          max_count_loop >= first + incr &&
+          max_count_fan >= first + incr);
+
+   /* no splitting required */
+   if (count <= max_count_simple) {
+      SEGMENT_SIMPLE(0x0, start, count);
+   }
+   else {
+      const unsigned rollback = first - incr;
+      unsigned flags = DRAW_SPLIT_AFTER, seg_start = 0, seg_max;
+
+      /*
+       * Both count and seg_max below are explicitly trimmed.  Because
+       *
+       *   seg_start = N * (seg_max - rollback) = N' * incr,
+       *
+       * we have
+       *
+       *   remaining = count - seg_start = first + N'' * incr.
+       *
+       * That is, remaining is implicitly trimmed.
+       */
+      switch (prim) {
+      case PIPE_PRIM_POINTS:
+      case PIPE_PRIM_LINES:
+      case PIPE_PRIM_LINE_STRIP:
+      case PIPE_PRIM_TRIANGLES:
+      case PIPE_PRIM_TRIANGLE_STRIP:
+      case PIPE_PRIM_QUADS:
+      case PIPE_PRIM_QUAD_STRIP:
+      case PIPE_PRIM_LINES_ADJACENCY:
+      case PIPE_PRIM_LINE_STRIP_ADJACENCY:
+      case PIPE_PRIM_TRIANGLES_ADJACENCY:
+      case PIPE_PRIM_TRIANGLE_STRIP_ADJACENCY:
+         seg_max =
+            draw_pt_trim_count(MIN2(max_count_simple, count), first, incr);
+         if (prim == PIPE_PRIM_TRIANGLE_STRIP ||
+             prim == PIPE_PRIM_TRIANGLE_STRIP_ADJACENCY) {
+            /* make sure we flush even number of triangles at a time */
+            if (seg_max < count && !(((seg_max - first) / incr) & 1))
+               seg_max -= incr;
+         }
+
+         do {
+            const unsigned remaining = count - seg_start;
+
+            if (remaining > seg_max) {
+               SEGMENT_SIMPLE(flags, start + seg_start, seg_max);
+               seg_start += seg_max - rollback;
+
+               flags |= DRAW_SPLIT_BEFORE;
+            }
+            else {
+               flags &= ~DRAW_SPLIT_AFTER;
+
+               SEGMENT_SIMPLE(flags, start + seg_start, remaining);
+               seg_start += remaining;
+            }
+         } while (seg_start < count);
+         break;
+
+      case PIPE_PRIM_LINE_LOOP:
+         seg_max =
+            draw_pt_trim_count(MIN2(max_count_loop, count), first, incr);
+
+         do {
+            const unsigned remaining = count - seg_start;
+
+            if (remaining > seg_max) {
+               SEGMENT_LOOP(flags, start + seg_start, seg_max, start);
+               seg_start += seg_max - rollback;
+
+               flags |= DRAW_SPLIT_BEFORE;
+            }
+            else {
+               flags &= ~DRAW_SPLIT_AFTER;
+
+               SEGMENT_LOOP(flags, start + seg_start, remaining, start);
+               seg_start += remaining;
+            }
+         } while (seg_start < count);
+         break;
+
+      case PIPE_PRIM_TRIANGLE_FAN:
+      case PIPE_PRIM_POLYGON:
+         seg_max =
+            draw_pt_trim_count(MIN2(max_count_fan, count), first, incr);
+
+         do {
+            const unsigned remaining = count - seg_start;
+
+            if (remaining > seg_max) {
+               SEGMENT_FAN(flags, start + seg_start, seg_max, start);
+               seg_start += seg_max - rollback;
+
+               flags |= DRAW_SPLIT_BEFORE;
+            }
+            else {
+               flags &= ~DRAW_SPLIT_AFTER;
+
+               SEGMENT_FAN(flags, start + seg_start, remaining, start);
+               seg_start += remaining;
+            }
+         } while (seg_start < count);
+         break;
+
+      default:
+         assert(0);
+         break;
+      }
+   }
+}
+
+#undef FUNC
+#undef FUNC_VARS
+#undef LOCAL_VARS
+
+#undef SEGMENT_SIMPLE
+#undef SEGMENT_LOOP
+#undef SEGMENT_FAN