path: root/src/mesa/drivers/dri/intel/intel_buffer_objects.c

/**************************************************************************
 * 
 * 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 "main/imports.h"
#include "main/mtypes.h"
#include "main/macros.h"
#include "main/bufferobj.h"

#include "intel_blit.h"
#include "intel_buffer_objects.h"
#include "intel_batchbuffer.h"
#include "intel_context.h"
#include "intel_fbo.h"
#include "intel_mipmap_tree.h"
#include "intel_regions.h"

static GLboolean
intel_bufferobj_unmap(GLcontext * ctx,
                      GLenum target, struct gl_buffer_object *obj);

/** Allocates a new drm_intel_bo to store the data for the buffer object. */
static void
intel_bufferobj_alloc_buffer(struct intel_context *intel,
			     struct intel_buffer_object *intel_obj)
{
   intel_obj->buffer = drm_intel_bo_alloc(intel->bufmgr, "bufferobj",
					  intel_obj->Base.Size, 64);
}

/**
 * There is some duplication between mesa's bufferobjects and our
 * bufmgr buffers.  Both have an integer handle and a hashtable to
 * lookup an opaque structure.  It would be nice if the handles and
 * internal structure where somehow shared.
 */
static struct gl_buffer_object *
intel_bufferobj_alloc(GLcontext * ctx, GLuint name, GLenum target)
{
   struct intel_buffer_object *obj = CALLOC_STRUCT(intel_buffer_object);

   _mesa_initialize_buffer_object(&obj->Base, name, target);

   obj->buffer = NULL;

   return &obj->Base;
}

/* Break the COW tie to the region.  The region gets to keep the data.
 */
void
intel_bufferobj_release_region(struct intel_context *intel,
                               struct intel_buffer_object *intel_obj)
{
   assert(intel_obj->region->buffer == intel_obj->buffer);
   intel_obj->region->pbo = NULL;
   intel_obj->region = NULL;

   drm_intel_bo_unreference(intel_obj->buffer);
   intel_obj->buffer = NULL;
}

/* Break the COW tie to the region.  Both the pbo and the region end
 * up with a copy of the data.
 */
void
intel_bufferobj_cow(struct intel_context *intel,
                    struct intel_buffer_object *intel_obj)
{
   assert(intel_obj->region);
   intel_region_cow(intel, intel_obj->region);
}


/**
 * Deallocate/free a vertex/pixel buffer object.
 * Called via glDeleteBuffersARB().
 */
static void
intel_bufferobj_free(GLcontext * ctx, struct gl_buffer_object *obj)
{
   struct intel_context *intel = intel_context(ctx);
   struct intel_buffer_object *intel_obj = intel_buffer_object(obj);

   assert(intel_obj);

   /* Buffer objects are automatically unmapped when deleting according
    * to the spec, but Mesa doesn't do UnmapBuffer for us at context destroy
    * (though it does if you call glDeleteBuffers)
    */
   if (obj->Pointer)
      intel_bufferobj_unmap(ctx, 0, obj);

   free(intel_obj->sys_buffer);
   if (intel_obj->region) {
      intel_bufferobj_release_region(intel, intel_obj);
   }
   else if (intel_obj->buffer) {
      drm_intel_bo_unreference(intel_obj->buffer);
   }

   free(intel_obj);
}



/**
 * Allocate space for and store data in a buffer object.  Any data that was
 * previously stored in the buffer object is lost.  If data is NULL,
 * memory will be allocated, but no copy will occur.
 * Called via ctx->Driver.BufferData().
 * \return GL_TRUE for success, GL_FALSE if out of memory
 */
static GLboolean
intel_bufferobj_data(GLcontext * ctx,
                     GLenum target,
                     GLsizeiptrARB size,
                     const GLvoid * data,
                     GLenum usage, struct gl_buffer_object *obj)
{
   struct intel_context *intel = intel_context(ctx);
   struct intel_buffer_object *intel_obj = intel_buffer_object(obj);

   intel_obj->Base.Size = size;
   intel_obj->Base.Usage = usage;

   assert(!obj->Pointer); /* Mesa should have unmapped it */

   if (intel_obj->region)
      intel_bufferobj_release_region(intel, intel_obj);

   if (intel_obj->buffer != NULL) {
      drm_intel_bo_unreference(intel_obj->buffer);
      intel_obj->buffer = NULL;
   }
   free(intel_obj->sys_buffer);
   intel_obj->sys_buffer = NULL;

   if (size != 0) {
#ifdef I915
      /* On pre-965, stick VBOs in system memory, as we're always doing swtnl
       * with their contents anyway.
       */
      if (target == GL_ARRAY_BUFFER || target == GL_ELEMENT_ARRAY_BUFFER) {
	 intel_obj->sys_buffer = malloc(size);
	 if (intel_obj->sys_buffer != NULL) {
	    if (data != NULL)
	       memcpy(intel_obj->sys_buffer, data, size);
	    return GL_TRUE;
	 }
      }
#endif
      intel_bufferobj_alloc_buffer(intel, intel_obj);
      if (!intel_obj->buffer)
         return GL_FALSE;

      if (data != NULL)
	 drm_intel_bo_subdata(intel_obj->buffer, 0, size, data);
   }

   return GL_TRUE;
}


/**
 * Replace data in a subrange of buffer object.  If the data range
 * specified by size + offset extends beyond the end of the buffer or
 * if data is NULL, no copy is performed.
 * Called via glBufferSubDataARB().
 */
static void
intel_bufferobj_subdata(GLcontext * ctx,
                        GLenum target,
                        GLintptrARB offset,
                        GLsizeiptrARB size,
                        const GLvoid * data, struct gl_buffer_object *obj)
{
   struct intel_context *intel = intel_context(ctx);
   struct intel_buffer_object *intel_obj = intel_buffer_object(obj);

   assert(intel_obj);

   if (intel_obj->region)
      intel_bufferobj_cow(intel, intel_obj);

   if (intel_obj->sys_buffer)
      memcpy((char *)intel_obj->sys_buffer + offset, data, size);
   else {
      /* Flush any existing batchbuffer that might reference this data. */
      if (drm_intel_bo_busy(intel_obj->buffer) ||
	  drm_intel_bo_references(intel->batch->buf, intel_obj->buffer)) {
	 drm_intel_bo *temp_bo;

	 temp_bo = drm_intel_bo_alloc(intel->bufmgr, "subdata temp", size, 64);

	 drm_intel_bo_subdata(temp_bo, 0, size, data);

	 intel_emit_linear_blit(intel,
				intel_obj->buffer, offset,
				temp_bo, 0,
				size);

	 drm_intel_bo_unreference(temp_bo);
      } else {
	 drm_intel_bo_subdata(intel_obj->buffer, offset, size, data);
      }
   }
}


/**
 * Called via glGetBufferSubDataARB().
 */
static void
intel_bufferobj_get_subdata(GLcontext * ctx,
                            GLenum target,
                            GLintptrARB offset,
                            GLsizeiptrARB size,
                            GLvoid * data, struct gl_buffer_object *obj)
{
   struct intel_buffer_object *intel_obj = intel_buffer_object(obj);

   assert(intel_obj);
   if (intel_obj->sys_buffer)
      memcpy(data, (char *)intel_obj->sys_buffer + offset, size);
   else
      drm_intel_bo_get_subdata(intel_obj->buffer, offset, size, data);
}



/**
 * Called via glMapBufferARB().
 */
static void *
intel_bufferobj_map(GLcontext * ctx,
                    GLenum target,
                    GLenum access, struct gl_buffer_object *obj)
{
   struct intel_context *intel = intel_context(ctx);
   struct intel_buffer_object *intel_obj = intel_buffer_object(obj);
   GLboolean read_only = (access == GL_READ_ONLY_ARB);
   GLboolean write_only = (access == GL_WRITE_ONLY_ARB);

   assert(intel_obj);

   if (intel_obj->sys_buffer) {
      obj->Pointer = intel_obj->sys_buffer;
      obj->Length = obj->Size;
      obj->Offset = 0;
      return obj->Pointer;
   }

   /* Flush any existing batchbuffer that might reference this data. */
   if (drm_intel_bo_references(intel->batch->buf, intel_obj->buffer))
      intel_flush(ctx);

   if (intel_obj->region)
      intel_bufferobj_cow(intel, intel_obj);

   if (intel_obj->buffer == NULL) {
      obj->Pointer = NULL;
      return NULL;
   }

   if (write_only) {
      drm_intel_gem_bo_map_gtt(intel_obj->buffer);
      intel_obj->mapped_gtt = GL_TRUE;
   } else {
      drm_intel_bo_map(intel_obj->buffer, !read_only);
      intel_obj->mapped_gtt = GL_FALSE;
   }

   obj->Pointer = intel_obj->buffer->virtual;
   obj->Length = obj->Size;
   obj->Offset = 0;

   return obj->Pointer;
}

/**
 * Called via glMapBufferRange().
 *
 * The goal of this extension is to allow apps to accumulate their rendering
 * at the same time as they accumulate their buffer object.  Without it,
 * you'd end up blocking on execution of rendering every time you mapped
 * the buffer to put new data in.
 *
 * We support it in 3 ways: If unsynchronized, then don't bother
 * flushing the batchbuffer before mapping the buffer, which can save blocking
 * in many cases.  If we would still block, and they allow the whole buffer
 * to be invalidated, then just allocate a new buffer to replace the old one.
 * If not, and we'd block, and they allow the subrange of the buffer to be
 * invalidated, then we can make a new little BO, let them write into that,
 * and blit it into the real BO at unmap time.
 */
static void *
intel_bufferobj_map_range(GLcontext * ctx,
			  GLenum target, GLintptr offset, GLsizeiptr length,
			  GLbitfield access, struct gl_buffer_object *obj)
{
   struct intel_context *intel = intel_context(ctx);
   struct intel_buffer_object *intel_obj = intel_buffer_object(obj);

   assert(intel_obj);

   /* _mesa_MapBufferRange (GL entrypoint) sets these, but the vbo module also
    * internally uses our functions directly.
    */
   obj->Offset = offset;
   obj->Length = length;
   obj->AccessFlags = access;

   if (intel_obj->sys_buffer) {
      obj->Pointer = intel_obj->sys_buffer + offset;
      return obj->Pointer;
   }

   if (intel_obj->region)
      intel_bufferobj_cow(intel, intel_obj);

   /* If the mapping is synchronized with other GL operations, flush
    * the batchbuffer so that GEM knows about the buffer access for later
    * syncing.
    */
   if (!(access & GL_MAP_UNSYNCHRONIZED_BIT) &&
       drm_intel_bo_references(intel->batch->buf, intel_obj->buffer))
      intel_flush(ctx);

   if (intel_obj->buffer == NULL) {
      obj->Pointer = NULL;
      return NULL;
   }

   /* If the user doesn't care about existing buffer contents and mapping
    * would cause us to block, then throw out the old buffer.
    */
   if (!(access & GL_MAP_UNSYNCHRONIZED_BIT) &&
       (access & GL_MAP_INVALIDATE_BUFFER_BIT) &&
       drm_intel_bo_busy(intel_obj->buffer)) {
      drm_intel_bo_unreference(intel_obj->buffer);
      intel_obj->buffer = drm_intel_bo_alloc(intel->bufmgr, "bufferobj",
					     intel_obj->Base.Size, 64);
   }

   /* If the user is mapping a range of an active buffer object but
    * doesn't require the current contents of that range, make a new
    * BO, and we'll copy what they put in there out at unmap or
    * FlushRange time.
    */
   if ((access & GL_MAP_INVALIDATE_RANGE_BIT) &&
       drm_intel_bo_busy(intel_obj->buffer)) {
      if (access & GL_MAP_FLUSH_EXPLICIT_BIT) {
	 intel_obj->range_map_buffer = malloc(length);
	 obj->Pointer = intel_obj->range_map_buffer;
      } else {
	 intel_obj->range_map_bo = drm_intel_bo_alloc(intel->bufmgr,
						      "range map",
						      length, 64);
	 if (!(access & GL_MAP_READ_BIT)) {
	    drm_intel_gem_bo_map_gtt(intel_obj->range_map_bo);
	    intel_obj->mapped_gtt = GL_TRUE;
	 } else {
	    drm_intel_bo_map(intel_obj->range_map_bo,
			     (access & GL_MAP_WRITE_BIT) != 0);
	    intel_obj->mapped_gtt = GL_FALSE;
	 }
	 obj->Pointer = intel_obj->range_map_bo->virtual;
      }
      return obj->Pointer;
   }

   if (!(access & GL_MAP_READ_BIT)) {
      drm_intel_gem_bo_map_gtt(intel_obj->buffer);
      intel_obj->mapped_gtt = GL_TRUE;
   } else {
      drm_intel_bo_map(intel_obj->buffer, (access & GL_MAP_WRITE_BIT) != 0);
      intel_obj->mapped_gtt = GL_FALSE;
   }

   obj->Pointer = intel_obj->buffer->virtual + offset;
   return obj->Pointer;
}

/* Ideally we'd use a BO to avoid taking up cache space for the temporary
 * data, but FlushMappedBufferRange may be followed by further writes to
 * the pointer, so we would have to re-map after emitting our blit, which
 * would defeat the point.
 */
static void
intel_bufferobj_flush_mapped_range(GLcontext *ctx, GLenum target,
				   GLintptr offset, GLsizeiptr length,
				   struct gl_buffer_object *obj)
{
   struct intel_context *intel = intel_context(ctx);
   struct intel_buffer_object *intel_obj = intel_buffer_object(obj);
   drm_intel_bo *temp_bo;

   /* Unless we're in the range map using a temporary system buffer,
    * there's no work to do.
    */
   if (intel_obj->range_map_buffer == NULL)
      return;

   temp_bo = drm_intel_bo_alloc(intel->bufmgr, "range map flush", length, 64);

   drm_intel_bo_subdata(temp_bo, 0, length, intel_obj->range_map_buffer);

   intel_emit_linear_blit(intel,
			  intel_obj->buffer, obj->Offset + offset,
			  temp_bo, 0,
			  length);

   drm_intel_bo_unreference(temp_bo);
}


/**
 * Called via glUnmapBuffer().
 */
static GLboolean
intel_bufferobj_unmap(GLcontext * ctx,
                      GLenum target, struct gl_buffer_object *obj)
{
   struct intel_context *intel = intel_context(ctx);
   struct intel_buffer_object *intel_obj = intel_buffer_object(obj);

   assert(intel_obj);
   assert(obj->Pointer);
   if (intel_obj->sys_buffer != NULL) {
      /* always keep the mapping around. */
   } else if (intel_obj->range_map_buffer != NULL) {
      /* Since we've emitted some blits to buffers that will (likely) be used
       * in rendering operations in other cache domains in this batch, emit a
       * flush.  Once again, we wish for a domain tracker in libdrm to cover
       * usage inside of a batchbuffer.
       */
      intel_batchbuffer_emit_mi_flush(intel->batch);
      free(intel_obj->range_map_buffer);
      intel_obj->range_map_buffer = NULL;
   } else if (intel_obj->range_map_bo != NULL) {
      if (intel_obj->mapped_gtt) {
	 drm_intel_gem_bo_unmap_gtt(intel_obj->range_map_bo);
      } else {
	 drm_intel_bo_unmap(intel_obj->range_map_bo);
      }

      intel_emit_linear_blit(intel,
			     intel_obj->buffer, obj->Offset,
			     intel_obj->range_map_bo, 0,
			     obj->Length);

      /* Since we've emitted some blits to buffers that will (likely) be used
       * in rendering operations in other cache domains in this batch, emit a
       * flush.  Once again, we wish for a domain tracker in libdrm to cover
       * usage inside of a batchbuffer.
       */
      intel_batchbuffer_emit_mi_flush(intel->batch);

      drm_intel_bo_unreference(intel_obj->range_map_bo);
      intel_obj->range_map_bo = NULL;
   } else if (intel_obj->buffer != NULL) {
      if (intel_obj->mapped_gtt) {
	 drm_intel_gem_bo_unmap_gtt(intel_obj->buffer);
      } else {
	 drm_intel_bo_unmap(intel_obj->buffer);
      }
   }
   obj->Pointer = NULL;
   obj->Offset = 0;
   obj->Length = 0;

   return GL_TRUE;
}

drm_intel_bo *
intel_bufferobj_buffer(struct intel_context *intel,
                       struct intel_buffer_object *intel_obj, GLuint flag)
{
   if (intel_obj->region) {
      if (flag == INTEL_WRITE_PART)
         intel_bufferobj_cow(intel, intel_obj);
      else if (flag == INTEL_WRITE_FULL) {
         intel_bufferobj_release_region(intel, intel_obj);
	 intel_bufferobj_alloc_buffer(intel, intel_obj);
      }
   }

   if (intel_obj->buffer == NULL) {
      void *sys_buffer = intel_obj->sys_buffer;

      /* only one of buffer and sys_buffer could be non-NULL */
      intel_bufferobj_alloc_buffer(intel, intel_obj);
      intel_obj->sys_buffer = NULL;

      intel_bufferobj_subdata(&intel->ctx,
			      GL_ARRAY_BUFFER_ARB,
			      0,
			      intel_obj->Base.Size,
			      sys_buffer,
			      &intel_obj->Base);
      free(sys_buffer);
      intel_obj->sys_buffer = NULL;
   }

   return intel_obj->buffer;
}

static void
intel_bufferobj_copy_subdata(GLcontext *ctx,
			     struct gl_buffer_object *src,
			     struct gl_buffer_object *dst,
			     GLintptr read_offset, GLintptr write_offset,
			     GLsizeiptr size)
{
   struct intel_context *intel = intel_context(ctx);
   struct intel_buffer_object *intel_src = intel_buffer_object(src);
   struct intel_buffer_object *intel_dst = intel_buffer_object(dst);
   drm_intel_bo *src_bo, *dst_bo;

   if (size == 0)
      return;

   /* If we're in system memory, just map and memcpy. */
   if (intel_src->sys_buffer || intel_dst->sys_buffer) {
      /* The same buffer may be used, but note that regions copied may
       * not overlap.
       */
      if (src == dst) {
	 char *ptr = intel_bufferobj_map(ctx, GL_COPY_WRITE_BUFFER,
					 GL_READ_WRITE, dst);
	 memcpy(ptr + write_offset, ptr + read_offset, size);
	 intel_bufferobj_unmap(ctx, GL_COPY_WRITE_BUFFER, dst);
      } else {
	 const char *src_ptr;
	 char *dst_ptr;

	 src_ptr =  intel_bufferobj_map(ctx, GL_COPY_READ_BUFFER,
					GL_READ_ONLY, src);
	 dst_ptr =  intel_bufferobj_map(ctx, GL_COPY_WRITE_BUFFER,
					GL_WRITE_ONLY, dst);

	 memcpy(dst_ptr + write_offset, src_ptr + read_offset, size);

	 intel_bufferobj_unmap(ctx, GL_COPY_READ_BUFFER, src);
	 intel_bufferobj_unmap(ctx, GL_COPY_WRITE_BUFFER, dst);
      }
   }

   /* Otherwise, we have real BOs, so blit them. */

   dst_bo = intel_bufferobj_buffer(intel, intel_dst, INTEL_WRITE_PART);
   src_bo = intel_bufferobj_buffer(intel, intel_src, INTEL_READ);

   intel_emit_linear_blit(intel,
			  dst_bo, write_offset,
			  src_bo, read_offset, size);

   /* Since we've emitted some blits to buffers that will (likely) be used
    * in rendering operations in other cache domains in this batch, emit a
    * flush.  Once again, we wish for a domain tracker in libdrm to cover
    * usage inside of a batchbuffer.
    */
   intel_batchbuffer_emit_mi_flush(intel->batch);
}

#if FEATURE_APPLE_object_purgeable
static GLenum
intel_buffer_purgeable(GLcontext * ctx,
                       drm_intel_bo *buffer,
                       GLenum option)
{
   int retained = 0;

   if (buffer != NULL)
      retained = drm_intel_bo_madvise (buffer, I915_MADV_DONTNEED);

   return retained ? GL_VOLATILE_APPLE : GL_RELEASED_APPLE;
}

static GLenum
intel_buffer_object_purgeable(GLcontext * ctx,
                              struct gl_buffer_object *obj,
                              GLenum option)
{
   struct intel_buffer_object *intel;

   intel = intel_buffer_object (obj);
   if (intel->buffer != NULL)
      return intel_buffer_purgeable (ctx, intel->buffer, option);

   if (option == GL_RELEASED_APPLE) {
      if (intel->sys_buffer != NULL) {
         free(intel->sys_buffer);
         intel->sys_buffer = NULL;
      }

      return GL_RELEASED_APPLE;
   } else {
      /* XXX Create the buffer and madvise(MADV_DONTNEED)? */
      return intel_buffer_purgeable (ctx,
                                     intel_bufferobj_buffer(intel_context(ctx),
                                                            intel, INTEL_READ),
                                     option);
   }
}

static GLenum
intel_texture_object_purgeable(GLcontext * ctx,
                               struct gl_texture_object *obj,
                               GLenum option)
{
   struct intel_texture_object *intel;

   intel = intel_texture_object(obj);
   if (intel->mt == NULL || intel->mt->region == NULL)
      return GL_RELEASED_APPLE;

   return intel_buffer_purgeable (ctx, intel->mt->region->buffer, option);
}

static GLenum
intel_render_object_purgeable(GLcontext * ctx,
                              struct gl_renderbuffer *obj,
                              GLenum option)
{
   struct intel_renderbuffer *intel;

   intel = intel_renderbuffer(obj);
   if (intel->region == NULL)
      return GL_RELEASED_APPLE;

   return intel_buffer_purgeable (ctx, intel->region->buffer, option);
}

static GLenum
intel_buffer_unpurgeable(GLcontext * ctx,
                         drm_intel_bo *buffer,
                         GLenum option)
{
   int retained;

   retained = 0;
   if (buffer != NULL)
      retained = drm_intel_bo_madvise (buffer, I915_MADV_WILLNEED);

   return retained ? GL_RETAINED_APPLE : GL_UNDEFINED_APPLE;
}

static GLenum
intel_buffer_object_unpurgeable(GLcontext * ctx,
                                struct gl_buffer_object *obj,
                                GLenum option)
{
   return intel_buffer_unpurgeable (ctx, intel_buffer_object (obj)->buffer, option);
}

static GLenum
intel_texture_object_unpurgeable(GLcontext * ctx,
                                 struct gl_texture_object *obj,
                                 GLenum option)
{
   struct intel_texture_object *intel;

   intel = intel_texture_object(obj);
   if (intel->mt == NULL || intel->mt->region == NULL)
      return GL_UNDEFINED_APPLE;

   return intel_buffer_unpurgeable (ctx, intel->mt->region->buffer, option);
}

static GLenum
intel_render_object_unpurgeable(GLcontext * ctx,
                                struct gl_renderbuffer *obj,
                                GLenum option)
{
   struct intel_renderbuffer *intel;

   intel = intel_renderbuffer(obj);
   if (intel->region == NULL)
      return GL_UNDEFINED_APPLE;

   return intel_buffer_unpurgeable (ctx, intel->region->buffer, option);
}
#endif

void
intelInitBufferObjectFuncs(struct dd_function_table *functions)
{
   functions->NewBufferObject = intel_bufferobj_alloc;
   functions->DeleteBuffer = intel_bufferobj_free;
   functions->BufferData = intel_bufferobj_data;
   functions->BufferSubData = intel_bufferobj_subdata;
   functions->GetBufferSubData = intel_bufferobj_get_subdata;
   functions->MapBuffer = intel_bufferobj_map;
   functions->MapBufferRange = intel_bufferobj_map_range;
   functions->FlushMappedBufferRange = intel_bufferobj_flush_mapped_range;
   functions->UnmapBuffer = intel_bufferobj_unmap;
   functions->CopyBufferSubData = intel_bufferobj_copy_subdata;

#if FEATURE_APPLE_object_purgeable
   functions->BufferObjectPurgeable = intel_buffer_object_purgeable;
   functions->TextureObjectPurgeable = intel_texture_object_purgeable;
   functions->RenderObjectPurgeable = intel_render_object_purgeable;

   functions->BufferObjectUnpurgeable = intel_buffer_object_unpurgeable;
   functions->TextureObjectUnpurgeable = intel_texture_object_unpurgeable;
   functions->RenderObjectUnpurgeable = intel_render_object_unpurgeable;
#endif
}