A version of the i915tex driver with all drawing code removed.

This is intended to support the softpipe development work.  More code
will be removed and pushed into softpipe until this basicially becomes
the DRI/GLX interface for that driver.

1 files changed, 792 insertions, 0 deletions

diff --git a/src/mesa/drivers/dri/i915pipe/intel_buffers.c b/src/mesa/drivers/dri/i915pipe/intel_buffers.c
new file mode 100644
index 0000000000..7684e36e3b
--- /dev/null
+++ b/src/mesa/drivers/dri/i915pipe/intel_buffers.c
@@ -0,0 +1,792 @@
+/**************************************************************************
+ * 
+ * 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 "intel_screen.h"
+#include "intel_context.h"
+#include "intel_blit.h"
+#include "intel_buffers.h"
+#include "intel_depthstencil.h"
+#include "intel_fbo.h"
+#include "intel_tris.h"
+#include "intel_regions.h"
+#include "intel_batchbuffer.h"
+#include "intel_reg.h"
+#include "context.h"
+#include "utils.h"
+#include "drirenderbuffer.h"
+#include "framebuffer.h"
+#include "swrast/swrast.h"
+#include "vblank.h"
+
+
+/* This block can be removed when libdrm >= 2.3.1 is required */
+
+#ifndef DRM_VBLANK_FLIP
+
+#define DRM_VBLANK_FLIP 0x8000000
+
+typedef struct drm_i915_flip {
+   int pipes;
+} drm_i915_flip_t;
+
+#undef DRM_IOCTL_I915_FLIP
+#define DRM_IOCTL_I915_FLIP DRM_IOW(DRM_COMMAND_BASE + DRM_I915_FLIP, \
+				    drm_i915_flip_t)
+
+#endif
+
+
+/**
+ * XXX move this into a new dri/common/cliprects.c file.
+ */
+GLboolean
+intel_intersect_cliprects(drm_clip_rect_t * dst,
+                          const drm_clip_rect_t * a,
+                          const drm_clip_rect_t * b)
+{
+   GLint bx = b->x1;
+   GLint by = b->y1;
+   GLint bw = b->x2 - bx;
+   GLint bh = b->y2 - by;
+
+   if (bx < a->x1)
+      bw -= a->x1 - bx, bx = a->x1;
+   if (by < a->y1)
+      bh -= a->y1 - by, by = a->y1;
+   if (bx + bw > a->x2)
+      bw = a->x2 - bx;
+   if (by + bh > a->y2)
+      bh = a->y2 - by;
+   if (bw <= 0)
+      return GL_FALSE;
+   if (bh <= 0)
+      return GL_FALSE;
+
+   dst->x1 = bx;
+   dst->y1 = by;
+   dst->x2 = bx + bw;
+   dst->y2 = by + bh;
+
+   return GL_TRUE;
+}
+
+/**
+ * Return pointer to current color drawing region, or NULL.
+ */
+struct intel_region *
+intel_drawbuf_region(struct intel_context *intel)
+{
+   struct intel_renderbuffer *irbColor =
+      intel_renderbuffer(intel->ctx.DrawBuffer->_ColorDrawBuffers[0][0]);
+   if (irbColor)
+      return irbColor->region;
+   else
+      return NULL;
+}
+
+/**
+ * Return pointer to current color reading region, or NULL.
+ */
+struct intel_region *
+intel_readbuf_region(struct intel_context *intel)
+{
+   struct intel_renderbuffer *irb
+      = intel_renderbuffer(intel->ctx.ReadBuffer->_ColorReadBuffer);
+   if (irb)
+      return irb->region;
+   else
+      return NULL;
+}
+
+
+
+/**
+ * Update the following fields for rendering:
+ *   intel->numClipRects
+ *   intel->pClipRects
+ */
+static void
+intelSetRenderbufferClipRects(struct intel_context *intel)
+{
+   /* zero-sized buffers might be legal? */
+   assert(intel->ctx.DrawBuffer->Width > 0);
+   assert(intel->ctx.DrawBuffer->Height > 0);
+   intel->fboRect.x1 = 0;
+   intel->fboRect.y1 = 0;
+   intel->fboRect.x2 = intel->ctx.DrawBuffer->Width;
+   intel->fboRect.y2 = intel->ctx.DrawBuffer->Height;
+   intel->numClipRects = 1;
+   intel->pClipRects = &intel->fboRect;
+}
+
+
+/**
+ * This will be called whenever the currently bound window is moved/resized.
+ * XXX: actually, it seems to NOT be called when the window is only moved (BP).
+ */
+void
+intelWindowMoved(struct intel_context *intel)
+{
+   GLcontext *ctx = &intel->ctx;
+   __DRIdrawablePrivate *dPriv = intel->driDrawable;
+   struct intel_framebuffer *intel_fb = dPriv->driverPrivate;
+
+   if (!intel->ctx.DrawBuffer) {
+      /* when would this happen? -BP */
+      assert(0);
+      intel->numClipRects = 0;
+   }
+
+   /* Update Mesa's notion of window size */
+   driUpdateFramebufferSize(ctx, dPriv);
+   intel_fb->Base.Initialized = GL_TRUE; /* XXX remove someday */
+
+   {
+      drmI830Sarea *sarea = intel->sarea;
+      drm_clip_rect_t drw_rect = { .x1 = dPriv->x, .x2 = dPriv->x + dPriv->w,
+				   .y1 = dPriv->y, .y2 = dPriv->y + dPriv->h };
+      drm_clip_rect_t pipeA_rect = { .x1 = sarea->pipeA_x, .y1 = sarea->pipeA_y,
+				     .x2 = sarea->pipeA_x + sarea->pipeA_w,
+				     .y2 = sarea->pipeA_y + sarea->pipeA_h };
+      drm_clip_rect_t pipeB_rect = { .x1 = sarea->pipeB_x, .y1 = sarea->pipeB_y,
+				     .x2 = sarea->pipeB_x + sarea->pipeB_w,
+				     .y2 = sarea->pipeB_y + sarea->pipeB_h };
+      GLint areaA = driIntersectArea( drw_rect, pipeA_rect );
+      GLint areaB = driIntersectArea( drw_rect, pipeB_rect );
+      GLuint flags = intel_fb->vblank_flags;
+      GLboolean pf_active;
+      GLint pf_pipes;
+
+      /* Update page flipping info
+       */
+      pf_pipes = 0;
+
+      if (areaA > 0)
+	 pf_pipes |= 1;
+
+      if (areaB > 0)
+	 pf_pipes |= 2;
+
+      intel_fb->pf_current_page = (intel->sarea->pf_current_page >>
+				   (intel_fb->pf_pipes & 0x2)) & 0x3;
+
+      intel_fb->pf_num_pages = 2 /*intel->intelScreen->third.handle ? 3 : 2*/;
+
+      pf_active = pf_pipes && (pf_pipes & intel->sarea->pf_active) == pf_pipes;
+
+      if (INTEL_DEBUG & DEBUG_LOCK)
+	 if (pf_active != intel_fb->pf_active)
+	    _mesa_printf("%s - Page flipping %sactive\n", __progname,
+			 pf_active ? "" : "in");
+
+      if (pf_active) {
+	 /* Sync pages between pipes if we're flipping on both at the same time */
+	 if (pf_pipes == 0x3 &&	pf_pipes != intel_fb->pf_pipes &&
+	     (intel->sarea->pf_current_page & 0x3) !=
+	     (((intel->sarea->pf_current_page) >> 2) & 0x3)) {
+	    drm_i915_flip_t flip;
+
+	    if (intel_fb->pf_current_page ==
+		(intel->sarea->pf_current_page & 0x3)) {
+	       /* XXX: This is ugly, but emitting two flips 'in a row' can cause
+		* lockups for unknown reasons.
+		*/
+               intel->sarea->pf_current_page =
+		  intel->sarea->pf_current_page & 0x3;
+	       intel->sarea->pf_current_page |=
+		  ((intel_fb->pf_current_page + intel_fb->pf_num_pages - 1) %
+		   intel_fb->pf_num_pages) << 2;
+
+	       flip.pipes = 0x2;
+	    } else {
+               intel->sarea->pf_current_page =
+		  intel->sarea->pf_current_page & (0x3 << 2);
+	       intel->sarea->pf_current_page |=
+		  (intel_fb->pf_current_page + intel_fb->pf_num_pages - 1) %
+		  intel_fb->pf_num_pages;
+
+	       flip.pipes = 0x1;
+	    }
+
+	    drmCommandWrite(intel->driFd, DRM_I915_FLIP, &flip, sizeof(flip));
+	 }
+
+	 intel_fb->pf_pipes = pf_pipes;
+      }
+
+      intel_fb->pf_active = pf_active;
+      intel_flip_renderbuffers(intel_fb);
+      intel_draw_buffer(&intel->ctx, intel->ctx.DrawBuffer);
+
+      /* Update vblank info
+       */
+      if (areaB > areaA || (areaA == areaB && areaB > 0)) {
+	 flags = intel_fb->vblank_flags | VBLANK_FLAG_SECONDARY;
+      } else {
+	 flags = intel_fb->vblank_flags & ~VBLANK_FLAG_SECONDARY;
+      }
+
+      if (flags != intel_fb->vblank_flags && intel_fb->vblank_flags &&
+	  !(intel_fb->vblank_flags & VBLANK_FLAG_NO_IRQ)) {
+	 drmVBlank vbl;
+	 int i;
+
+	 vbl.request.type = DRM_VBLANK_ABSOLUTE;
+
+	 if ( intel_fb->vblank_flags & VBLANK_FLAG_SECONDARY ) {
+	    vbl.request.type |= DRM_VBLANK_SECONDARY;
+	 }
+
+	 for (i = 0; i < intel_fb->pf_num_pages; i++) {
+	    if (!intel_fb->color_rb[i] ||
+		(intel_fb->vbl_waited - intel_fb->color_rb[i]->vbl_pending) <=
+		(1<<23))
+	       continue;
+
+	    vbl.request.sequence = intel_fb->color_rb[i]->vbl_pending;
+	    drmWaitVBlank(intel->driFd, &vbl);
+	 }
+
+	 intel_fb->vblank_flags = flags;
+	 driGetCurrentVBlank(dPriv, intel_fb->vblank_flags, &intel_fb->vbl_seq);
+	 intel_fb->vbl_waited = intel_fb->vbl_seq;
+
+	 for (i = 0; i < intel_fb->pf_num_pages; i++) {
+	    if (intel_fb->color_rb[i])
+	       intel_fb->color_rb[i]->vbl_pending = intel_fb->vbl_waited;
+	 }
+      }
+   }
+
+   /* This will be picked up by looking at the dirty state flags:
+    */
+
+   /* Update hardware scissor */
+//   ctx->Driver.Scissor(ctx, ctx->Scissor.X, ctx->Scissor.Y,
+//                       ctx->Scissor.Width, ctx->Scissor.Height);
+
+   /* Re-calculate viewport related state */
+//   ctx->Driver.DepthRange( ctx, ctx->Viewport.Near, ctx->Viewport.Far );
+}
+
+
+
+
+
+/**
+ * Called by ctx->Driver.Clear.
+ */
+static void
+intelClear(GLcontext *ctx, GLbitfield mask)
+{
+   const GLuint colorMask = *((GLuint *) & ctx->Color.ColorMask);
+   GLbitfield tri_mask = 0;
+   GLbitfield blit_mask = 0;
+   GLbitfield swrast_mask = 0;
+   struct gl_framebuffer *fb = ctx->DrawBuffer;
+   GLuint i;
+
+   if (0)
+      fprintf(stderr, "%s\n", __FUNCTION__);
+
+   /* HW color buffers (front, back, aux, generic FBO, etc) */
+   if (colorMask == ~0) {
+      /* clear all R,G,B,A */
+      /* XXX FBO: need to check if colorbuffers are software RBOs! */
+      blit_mask |= (mask & BUFFER_BITS_COLOR);
+   }
+   else {
+      /* glColorMask in effect */
+      tri_mask |= (mask & BUFFER_BITS_COLOR);
+   }
+
+   /* HW stencil */
+   if (mask & BUFFER_BIT_STENCIL) {
+      const struct intel_region *stencilRegion
+         = intel_get_rb_region(fb, BUFFER_STENCIL);
+      if (stencilRegion) {
+         /* have hw stencil */
+         if ((ctx->Stencil.WriteMask[0] & 0xff) != 0xff) {
+            /* not clearing all stencil bits, so use triangle clearing */
+            tri_mask |= BUFFER_BIT_STENCIL;
+         }
+         else {
+            /* clearing all stencil bits, use blitting */
+            blit_mask |= BUFFER_BIT_STENCIL;
+         }
+      }
+   }
+
+   /* HW depth */
+   if (mask & BUFFER_BIT_DEPTH) {
+      /* clear depth with whatever method is used for stencil (see above) */
+      if (tri_mask & BUFFER_BIT_STENCIL)
+         tri_mask |= BUFFER_BIT_DEPTH;
+      else
+         blit_mask |= BUFFER_BIT_DEPTH;
+   }
+
+   /* SW fallback clearing */
+   swrast_mask = mask & ~tri_mask & ~blit_mask;
+
+   for (i = 0; i < BUFFER_COUNT; i++) {
+      GLuint bufBit = 1 << i;
+      if ((blit_mask | tri_mask) & bufBit) {
+         if (!fb->Attachment[i].Renderbuffer->ClassID) {
+            blit_mask &= ~bufBit;
+            tri_mask &= ~bufBit;
+            swrast_mask |= bufBit;
+         }
+      }
+   }
+
+
+   intelFlush(ctx);             /* XXX intelClearWithBlit also does this */
+
+   if (blit_mask)
+      intelClearWithBlit(ctx, blit_mask);
+
+   if (swrast_mask | tri_mask)
+      _swrast_Clear(ctx, swrast_mask | tri_mask);
+}
+
+
+/* Emit wait for pending flips */
+void
+intel_wait_flips(struct intel_context *intel, GLuint batch_flags)
+{
+   struct intel_framebuffer *intel_fb =
+      (struct intel_framebuffer *) intel->ctx.DrawBuffer;
+   struct intel_renderbuffer *intel_rb =
+      intel_get_renderbuffer(&intel_fb->Base,
+			     intel_fb->Base._ColorDrawBufferMask[0] ==
+			     BUFFER_BIT_FRONT_LEFT ? BUFFER_FRONT_LEFT :
+			     BUFFER_BACK_LEFT);
+
+   if (intel_fb->Base.Name == 0 && intel_rb->pf_pending == intel_fb->pf_seq) {
+      GLint pf_pipes = intel_fb->pf_pipes;
+      BATCH_LOCALS;
+
+      /* Wait for pending flips to take effect */
+      BEGIN_BATCH(2, batch_flags);
+      OUT_BATCH(pf_pipes & 0x1 ? (MI_WAIT_FOR_EVENT | MI_WAIT_FOR_PLANE_A_FLIP)
+		: 0);
+      OUT_BATCH(pf_pipes & 0x2 ? (MI_WAIT_FOR_EVENT | MI_WAIT_FOR_PLANE_B_FLIP)
+		: 0);
+      ADVANCE_BATCH();
+
+      intel_rb->pf_pending--;
+   }
+}
+
+#if 0
+/* Flip the front & back buffers
+ */
+static GLboolean
+intelPageFlip(const __DRIdrawablePrivate * dPriv)
+{
+   struct intel_context *intel;
+   int ret;
+   struct intel_framebuffer *intel_fb = dPriv->driverPrivate;
+
+   if (INTEL_DEBUG & DEBUG_IOCTL)
+      fprintf(stderr, "%s\n", __FUNCTION__);
+
+   assert(dPriv);
+   assert(dPriv->driContextPriv);
+   assert(dPriv->driContextPriv->driverPrivate);
+
+   intel = (struct intel_context *) dPriv->driContextPriv->driverPrivate;
+
+   if (intel->intelScreen->drmMinor < 9)
+      return GL_FALSE;
+
+   intelFlush(&intel->ctx);
+
+   ret = 0;
+
+   LOCK_HARDWARE(intel);
+
+   if (dPriv->numClipRects && intel_fb->pf_active) {
+      drm_i915_flip_t flip;
+
+      flip.pipes = intel_fb->pf_pipes;
+
+      ret = drmCommandWrite(intel->driFd, DRM_I915_FLIP, &flip, sizeof(flip));
+   }
+
+   UNLOCK_HARDWARE(intel);
+
+   if (ret || !intel_fb->pf_active)
+      return GL_FALSE;
+
+   if (!dPriv->numClipRects) {
+      usleep(10000);	/* throttle invisible client 10ms */
+   }
+
+   intel_fb->pf_current_page = (intel->sarea->pf_current_page >>
+				(intel_fb->pf_pipes & 0x2)) & 0x3;
+
+   if (dPriv->numClipRects != 0) {
+      intel_get_renderbuffer(&intel_fb->Base, BUFFER_FRONT_LEFT)->pf_pending =
+      intel_get_renderbuffer(&intel_fb->Base, BUFFER_BACK_LEFT)->pf_pending =
+	 ++intel_fb->pf_seq;
+   }
+
+   intel_flip_renderbuffers(intel_fb);
+   intel_draw_buffer(&intel->ctx, &intel_fb->Base);
+
+   if (INTEL_DEBUG & DEBUG_IOCTL)
+      fprintf(stderr, "%s: success\n", __FUNCTION__);
+
+   return GL_TRUE;
+}
+#endif
+
+
+static GLboolean
+intelScheduleSwap(const __DRIdrawablePrivate * dPriv, GLboolean *missed_target)
+{
+   struct intel_framebuffer *intel_fb = dPriv->driverPrivate;
+   unsigned int interval = driGetVBlankInterval(dPriv, intel_fb->vblank_flags);
+   struct intel_context *intel =
+      intelScreenContext(dPriv->driScreenPriv->private);
+   const intelScreenPrivate *intelScreen = intel->intelScreen;
+   unsigned int target;
+   drm_i915_vblank_swap_t swap;
+   GLboolean ret;
+
+   if (!intel_fb->vblank_flags ||
+       (intel_fb->vblank_flags & VBLANK_FLAG_NO_IRQ) ||
+       intelScreen->drmMinor < (intel_fb->pf_active ? 9 : 6))
+      return GL_FALSE;
+
+   swap.seqtype = DRM_VBLANK_ABSOLUTE;
+
+   if (intel_fb->vblank_flags & VBLANK_FLAG_SYNC) {
+      swap.seqtype |= DRM_VBLANK_NEXTONMISS;
+   } else if (interval == 0) {
+      return GL_FALSE;
+   }
+
+   swap.drawable = dPriv->hHWDrawable;
+   target = swap.sequence = intel_fb->vbl_seq + interval;
+
+   if ( intel_fb->vblank_flags & VBLANK_FLAG_SECONDARY ) {
+      swap.seqtype |= DRM_VBLANK_SECONDARY;
+   }
+
+   LOCK_HARDWARE(intel);
+
+   intel_batchbuffer_flush(intel->batch);
+
+   if ( intel_fb->pf_active ) {
+      swap.seqtype |= DRM_VBLANK_FLIP;
+
+      intel_fb->pf_current_page = (((intel->sarea->pf_current_page >>
+				     (intel_fb->pf_pipes & 0x2)) & 0x3) + 1) %
+				  intel_fb->pf_num_pages;
+   }
+
+   if (!drmCommandWriteRead(intel->driFd, DRM_I915_VBLANK_SWAP, &swap,
+			    sizeof(swap))) {
+      intel_fb->vbl_seq = swap.sequence;
+      swap.sequence -= target;
+      *missed_target = swap.sequence > 0 && swap.sequence <= (1 << 23);
+
+      intel_get_renderbuffer(&intel_fb->Base, BUFFER_BACK_LEFT)->vbl_pending =
+	 intel_get_renderbuffer(&intel_fb->Base,
+				BUFFER_FRONT_LEFT)->vbl_pending =
+	 intel_fb->vbl_seq;
+
+      if (swap.seqtype & DRM_VBLANK_FLIP) {
+	 intel_flip_renderbuffers(intel_fb);
+	 intel_draw_buffer(&intel->ctx, intel->ctx.DrawBuffer);
+      }
+
+      ret = GL_TRUE;
+   } else {
+      if (swap.seqtype & DRM_VBLANK_FLIP) {
+	 intel_fb->pf_current_page = ((intel->sarea->pf_current_page >>
+					(intel_fb->pf_pipes & 0x2)) & 0x3) %
+				     intel_fb->pf_num_pages;
+      }
+
+      ret = GL_FALSE;
+   }
+
+   UNLOCK_HARDWARE(intel);
+
+   return ret;
+}
+
+void
+intelSwapBuffers(__DRIdrawablePrivate * dPriv)
+{
+   if (dPriv->driContextPriv && dPriv->driContextPriv->driverPrivate) {
+      GET_CURRENT_CONTEXT(ctx);
+      struct intel_context *intel;
+
+      if (ctx == NULL)
+	 return;
+
+      intel = intel_context(ctx);
+
+      if (ctx->Visual.doubleBufferMode) {
+	 GLboolean missed_target;
+	 struct intel_framebuffer *intel_fb = dPriv->driverPrivate;
+	 int64_t ust;
+
+	 _mesa_notifySwapBuffers(ctx);  /* flush pending rendering comands */
+
+         if (!intelScheduleSwap(dPriv, &missed_target)) {
+	    driWaitForVBlank(dPriv, &intel_fb->vbl_seq, intel_fb->vblank_flags,
+			     &missed_target);
+
+            intelCopyBuffer(dPriv, NULL);
+	 }
+
+	 intel_fb->swap_count++;
+	 (*dri_interface->getUST) (&ust);
+	 if (missed_target) {
+	    intel_fb->swap_missed_count++;
+	    intel_fb->swap_missed_ust = ust - intel_fb->swap_ust;
+	 }
+
+	 intel_fb->swap_ust = ust;
+      }
+   }
+   else {
+      /* XXX this shouldn't be an error but we can't handle it for now */
+      fprintf(stderr, "%s: drawable has no context!\n", __FUNCTION__);
+   }
+}
+
+void
+intelCopySubBuffer(__DRIdrawablePrivate * dPriv, int x, int y, int w, int h)
+{
+   if (dPriv->driContextPriv && dPriv->driContextPriv->driverPrivate) {
+      struct intel_context *intel =
+         (struct intel_context *) dPriv->driContextPriv->driverPrivate;
+      GLcontext *ctx = &intel->ctx;
+
+      if (ctx->Visual.doubleBufferMode) {
+         drm_clip_rect_t rect;
+	 /* fixup cliprect (driDrawable may have changed?) later */
+         rect.x1 = x;
+         rect.y1 = y;
+         rect.x2 = w;
+         rect.y2 = h;
+         _mesa_notifySwapBuffers(ctx);  /* flush pending rendering comands */
+         intelCopyBuffer(dPriv, &rect);
+      }
+   }
+   else {
+      /* XXX this shouldn't be an error but we can't handle it for now */
+      fprintf(stderr, "%s: drawable has no context!\n", __FUNCTION__);
+   }
+}
+
+
+/**
+ * Update the hardware state for drawing into a window or framebuffer object.
+ *
+ * Called by glDrawBuffer, glBindFramebufferEXT, MakeCurrent, and other
+ * places within the driver.
+ *
+ * Basically, this needs to be called any time the current framebuffer
+ * changes, the renderbuffers change, or we need to draw into different
+ * color buffers.
+ */
+void
+intel_draw_buffer(GLcontext * ctx, struct gl_framebuffer *fb)
+{
+   struct intel_context *intel = intel_context(ctx);
+   struct intel_region *colorRegion, *depthRegion = NULL;
+   struct intel_renderbuffer *irbDepth = NULL, *irbStencil = NULL;
+
+   if (!fb) {
+      /* this can happen during the initial context initialization */
+      return;
+   }
+
+   /* Do this here, not core Mesa, since this function is called from
+    * many places within the driver.
+    */
+   if (ctx->NewState & (_NEW_BUFFERS | _NEW_COLOR | _NEW_PIXEL)) {
+      /* this updates the DrawBuffer->_NumColorDrawBuffers fields, etc */
+      _mesa_update_framebuffer(ctx);
+      /* this updates the DrawBuffer's Width/Height if it's a FBO */
+      _mesa_update_draw_buffer_bounds(ctx);
+   }
+
+   if (fb->_Status != GL_FRAMEBUFFER_COMPLETE_EXT) {
+      /* this may occur when we're called by glBindFrameBuffer() during
+       * the process of someone setting up renderbuffers, etc.
+       */
+      /*_mesa_debug(ctx, "DrawBuffer: incomplete user FBO\n");*/
+      return;
+   }
+
+   if (fb->Name)
+      intel_validate_paired_depth_stencil(ctx, fb);
+
+   /*
+    * How many color buffers are we drawing into?
+    */
+   if (fb->_NumColorDrawBuffers[0] != 1) {
+      /* writing to 0 or 2 or 4 color buffers */
+      /*_mesa_debug(ctx, "Software rendering\n");*/
+      FALLBACK(intel, INTEL_FALLBACK_DRAW_BUFFER, GL_TRUE);
+   }
+   else {
+      /* draw to exactly one color buffer */
+      /*_mesa_debug(ctx, "Hardware rendering\n");*/
+      FALLBACK(intel, INTEL_FALLBACK_DRAW_BUFFER, GL_FALSE);
+   }
+
+   /*
+    * Get the intel_renderbuffer for the colorbuffer we're drawing into.
+    * And set up cliprects.
+    */
+   {
+      struct intel_renderbuffer *irb;
+      intelSetRenderbufferClipRects(intel);
+      irb = intel_renderbuffer(fb->_ColorDrawBuffers[0][0]);
+      colorRegion = (irb && irb->region) ? irb->region : NULL;
+   }
+
+   /* Update culling direction which changes depending on the
+    * orientation of the buffer:
+    */
+   if (ctx->Driver.FrontFace)
+      ctx->Driver.FrontFace(ctx, ctx->Polygon.FrontFace);
+   else
+      ctx->NewState |= _NEW_POLYGON;
+
+   if (!colorRegion) {
+      FALLBACK(intel, INTEL_FALLBACK_DRAW_BUFFER, GL_TRUE);
+   }
+   else {
+      FALLBACK(intel, INTEL_FALLBACK_DRAW_BUFFER, GL_FALSE);
+   }
+
+   /***
+    *** Get depth buffer region and check if we need a software fallback.
+    *** Note that the depth buffer is usually a DEPTH_STENCIL buffer.
+    ***/
+   if (fb->_DepthBuffer && fb->_DepthBuffer->Wrapped) {
+      irbDepth = intel_renderbuffer(fb->_DepthBuffer->Wrapped);
+      if (irbDepth && irbDepth->region) {
+         FALLBACK(intel, INTEL_FALLBACK_DEPTH_BUFFER, GL_FALSE);
+         depthRegion = irbDepth->region;
+      }
+      else {
+         FALLBACK(intel, INTEL_FALLBACK_DEPTH_BUFFER, GL_TRUE);
+         depthRegion = NULL;
+      }
+   }
+   else {
+      /* not using depth buffer */
+      FALLBACK(intel, INTEL_FALLBACK_DEPTH_BUFFER, GL_FALSE);
+      depthRegion = NULL;
+   }
+
+   /***
+    *** Stencil buffer
+    *** This can only be hardware accelerated if we're using a
+    *** combined DEPTH_STENCIL buffer (for now anyway).
+    ***/
+   if (fb->_StencilBuffer && fb->_StencilBuffer->Wrapped) {
+      irbStencil = intel_renderbuffer(fb->_StencilBuffer->Wrapped);
+      if (irbStencil && irbStencil->region) {
+         ASSERT(irbStencil->Base._ActualFormat == GL_DEPTH24_STENCIL8_EXT);
+         FALLBACK(intel, INTEL_FALLBACK_STENCIL_BUFFER, GL_FALSE);
+         /* need to re-compute stencil hw state */
+//         ctx->Driver.Enable(ctx, GL_STENCIL_TEST, ctx->Stencil.Enabled);
+         if (!depthRegion)
+            depthRegion = irbStencil->region;
+      }
+      else {
+         FALLBACK(intel, INTEL_FALLBACK_STENCIL_BUFFER, GL_TRUE);
+      }
+   }
+   else {
+      /* XXX FBO: instead of FALSE, pass ctx->Stencil.Enabled ??? */
+      FALLBACK(intel, INTEL_FALLBACK_STENCIL_BUFFER, GL_FALSE);
+      /* need to re-compute stencil hw state */
+//      ctx->Driver.Enable(ctx, GL_STENCIL_TEST, ctx->Stencil.Enabled);
+   }
+
+
+   /**
+    ** Release old regions, reference new regions
+    **/
+
+   //  intel->vtbl.set_draw_region(intel, colorRegion, depthRegion);
+
+   /* update viewport since it depends on window size */
+//   ctx->Driver.Viewport(ctx, ctx->Viewport.X, ctx->Viewport.Y,
+//                        ctx->Viewport.Width, ctx->Viewport.Height);
+
+   /* Update hardware scissor */
+//   ctx->Driver.Scissor(ctx, ctx->Scissor.X, ctx->Scissor.Y,
+//                       ctx->Scissor.Width, ctx->Scissor.Height);
+}
+
+
+static void
+intelDrawBuffer(GLcontext * ctx, GLenum mode)
+{
+   intel_draw_buffer(ctx, ctx->DrawBuffer);
+}
+
+
+static void
+intelReadBuffer(GLcontext * ctx, GLenum mode)
+{
+   if (ctx->ReadBuffer == ctx->DrawBuffer) {
+      /* This will update FBO completeness status.
+       * A framebuffer will be incomplete if the GL_READ_BUFFER setting
+       * refers to a missing renderbuffer.  Calling glReadBuffer can set
+       * that straight and can make the drawing buffer complete.
+       */
+      intel_draw_buffer(ctx, ctx->DrawBuffer);
+   }
+   /* Generally, functions which read pixels (glReadPixels, glCopyPixels, etc)
+    * reference ctx->ReadBuffer and do appropriate state checks.
+    */
+}
+
+
+void
+intelInitBufferFuncs(struct dd_function_table *functions)
+{
+   functions->Clear = intelClear;
+   functions->DrawBuffer = intelDrawBuffer;
+   functions->ReadBuffer = intelReadBuffer;
+}