util: implement util_clear_depth_stencil fallback

this doesn't really look terribly useful for drivers to use, but until
drivers use their own implementation provide this since some state trackers
really want to use these functions.

src/gallium/auxiliary/util/u_surface.c

@@ -199,7 +199,6 @@ util_resource_copy_region(struct pipe_context *pipe,
  * Fallback for pipe->clear_render_target() function.
  * XXX this looks too hackish to be really useful.
  * cpp > 4 looks like a gross hack at best...
- * and we're missing the equivalent clear_depth_stencil fallback.
  * Plus can't use these transfer fallbacks when clearing
  * multisampled surfaces for instance.
  */
@@ -278,3 +277,110 @@ util_clear_render_target(struct pipe_context *pipe,
    pipe->transfer_unmap(pipe, dst_trans);
    pipe->transfer_destroy(pipe, dst_trans);
 }
+
+/**
+ * Fallback for pipe->clear_stencil() function.
+ * sw fallback doesn't look terribly useful here.
+ * Plus can't use these transfer fallbacks when clearing
+ * multisampled surfaces for instance.
+ */
+void
+util_clear_depth_stencil(struct pipe_context *pipe,
+                         struct pipe_surface *dst,
+                         unsigned clear_flags,
+                         double depth,
+                         unsigned stencil,
+                         unsigned dstx, unsigned dsty,
+                         unsigned width, unsigned height)
+{
+   struct pipe_transfer *dst_trans;
+   ubyte *dst_map;
+   boolean need_rmw = FALSE;
+
+   if ((clear_flags & PIPE_CLEAR_DEPTHSTENCIL) &&
+       ((clear_flags & PIPE_CLEAR_DEPTHSTENCIL) != PIPE_CLEAR_DEPTHSTENCIL) &&
+       util_format_is_depth_and_stencil(dst->format))
+      need_rmw = TRUE;
+
+   assert(dst->texture);
+   if (!dst->texture)
+      return;
+   dst_trans = pipe_get_transfer(pipe,
+                                 dst->texture,
+                                 dst->face,
+                                 dst->level,
+                                 dst->zslice,
+                                 (need_rmw ? PIPE_TRANSFER_READ_WRITE :
+                                     PIPE_TRANSFER_WRITE),
+                                 dstx, dsty, width, height);
+
+   dst_map = pipe->transfer_map(pipe, dst_trans);
+
+   assert(dst_map);
+
+   if (dst_map) {
+      unsigned dst_stride = dst_trans->stride;
+      unsigned zstencil = util_pack_z_stencil(dst->texture->format, depth, stencil);
+      unsigned i, j;
+      assert(dst_trans->stride > 0);
+
+      switch (util_format_get_blocksize(dst->format)) {
+      case 1:
+         assert(dst->format == PIPE_FORMAT_S8_USCALED);
+         if(dst_stride == width)
+            memset(dst_map, (ubyte) zstencil, height * width);
+         else {
+            for (i = 0; i < height; i++) {
+               memset(dst_map, (ubyte) zstencil, width);
+               dst_map += dst_stride;
+            }
+         }
+         break;
+      case 2:
+         assert(dst->format == PIPE_FORMAT_Z16_UNORM);
+         for (i = 0; i < height; i++) {
+            uint16_t *row = (uint16_t *)dst_map;
+            for (j = 0; j < width; j++)
+               *row++ = (uint16_t) zstencil;
+            dst_map += dst_stride;
+            }
+         break;
+      case 4:
+         if (!need_rmw) {
+            for (i = 0; i < height; i++) {
+               uint32_t *row = (uint32_t *)dst_map;
+               for (j = 0; j < width; j++)
+                  *row++ = zstencil;
+               dst_map += dst_stride;
+            }
+         }
+         else {
+            uint32_t dst_mask;
+            if (dst->format == PIPE_FORMAT_Z24_UNORM_S8_USCALED)
+               dst_mask = 0xffffff00;
+            else {
+               assert(dst->format == PIPE_FORMAT_S8_USCALED_Z24_UNORM);
+               dst_mask = 0xffffff;
+            }
+            if (clear_flags & PIPE_CLEAR_DEPTH)
+               dst_mask = ~dst_mask;
+            for (i = 0; i < height; i++) {
+               uint32_t *row = (uint32_t *)dst_map;
+               for (j = 0; j < width; j++) {
+                  uint32_t tmp = *row & dst_mask;
+                  *row++ = tmp & (zstencil & ~dst_mask);
+               }
+               dst_map += dst_stride;
+            }
+         }
+        break;
+      case 8:
+      default:
+         assert(0);
+         break;
+      }
+   }
+
+   pipe->transfer_unmap(pipe, dst_trans);
+   pipe->transfer_destroy(pipe, dst_trans);
+}

src/gallium/auxiliary/util/u_surface.h

@@ -63,6 +63,14 @@ util_clear_render_target(struct pipe_context *pipe,
                          unsigned dstx, unsigned dsty,
                          unsigned width, unsigned height);
 
+extern void
+util_clear_depth_stencil(struct pipe_context *pipe,
+                         struct pipe_surface *dst,
+                         unsigned clear_flags,
+                         double depth,
+                         unsigned stencil,
+                         unsigned dstx, unsigned dsty,
+                         unsigned width, unsigned height);
 
 
 #endif /* U_SURFACE_H */