mga driver, brought over by Jon Smirl

1 files changed, 690 insertions, 0 deletions

diff --git a/src/mesa/drivers/dri/mga/mgapixel.c b/src/mesa/drivers/dri/mga/mgapixel.c
new file mode 100644
index 0000000000..0bc4b3fac5
--- /dev/null
+++ b/src/mesa/drivers/dri/mga/mgapixel.c
@@ -0,0 +1,690 @@
+/*
+ * Copyright 2000 Compaq Computer Inc. and VA Linux Systems, Inc.
+ * 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
+ * on 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
+ * VA LINUX SYSTEMS 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 <keith@tungstengraphics.com>
+ *    Gareth Hughes <gareth@valinux.com>
+ */
+/* $XFree86: xc/lib/GL/mesa/src/drv/mga/mgapixel.c,v 1.9 2002/11/05 17:46:08 tsi Exp $ */
+
+#include "enums.h"
+#include "mtypes.h"
+#include "macros.h"
+#include "texutil.h"
+#include "mgadd.h"
+#include "mgacontext.h"
+#include "mgaioctl.h"
+#include "mgapixel.h"
+#include "mgabuffers.h"
+
+#include "xf86drm.h"
+#include "mga_common.h"
+
+#include "swrast/swrast.h"
+
+#define IS_AGP_MEM( mmesa, p )						  \
+   ((unsigned long)mmesa->mgaScreen->buffers.map <= ((unsigned long)p) && \
+    (unsigned long)mmesa->mgaScreen->buffers.map +			  \
+    (unsigned long)mmesa->mgaScreen->buffers.size > ((unsigned long)p))
+#define AGP_OFFSET( mmesa, p )						  \
+     (((unsigned long)p) - (unsigned long)mmesa->mgaScreen->buffers.map)
+
+
+#if defined(MESA_packed_depth_stencil)
+static GLboolean
+check_depth_stencil_24_8( const GLcontext *ctx, GLenum type,
+			  const struct gl_pixelstore_attrib *packing,
+			  const void *pixels, GLint sz,
+			  GLint pitch )
+{
+   mgaContextPtr mmesa = MGA_CONTEXT(ctx);
+
+   return ( type == GL_UNSIGNED_INT_24_8_MESA &&
+	    ctx->Visual->DepthBits == 24 &&
+	    ctx->Visual->StencilBits == 8 &&
+	    mmesa->mgaScreen->cpp == 4 &&
+	    mmesa->hw_stencil &&
+	    !ctx->Pixel.IndexShift &&
+	    !ctx->Pixel.IndexOffset &&
+	    !ctx->Pixel.MapStencilFlag &&
+	    ctx->Pixel.DepthBias == 0.0 &&
+	    ctx->Pixel.DepthScale == 1.0 &&
+	    !packing->SwapBytes &&
+	    pitch % 32 == 0 &&
+	    pitch < 4096 );
+}
+#endif
+
+
+static GLboolean
+check_depth( const GLcontext *ctx, GLenum type,
+	     const struct gl_pixelstore_attrib *packing,
+	     const void *pixels, GLint sz, GLint pitch )
+{
+   mgaContextPtr mmesa = MGA_CONTEXT(ctx);
+
+   if ( IS_AGP_MEM( mmesa, pixels ) &&
+	!( ( type == GL_UNSIGNED_INT && mmesa->mgaScreen->cpp == 4 ) ||
+	   ( type == GL_UNSIGNED_SHORT && mmesa->mgaScreen->cpp == 2 ) ) )
+      return GL_FALSE;
+
+   return ( ctx->Pixel.DepthBias == 0.0 &&
+	    ctx->Pixel.DepthScale == 1.0 &&
+	    !packing->SwapBytes &&
+	    pitch % 32 == 0 &&
+	    pitch < 4096 );
+}
+
+
+static GLboolean
+check_color( const GLcontext *ctx, GLenum type, GLenum format,
+	     const struct gl_pixelstore_attrib *packing,
+	     const void *pixels, GLint sz, GLint pitch )
+{
+   mgaContextPtr mmesa = MGA_CONTEXT(ctx);
+   GLuint cpp = mmesa->mgaScreen->cpp;
+
+   /* Can't do conversions on agp reads/draws.
+    */
+   if ( IS_AGP_MEM( mmesa, pixels ) &&
+	!( pitch % 32 == 0 && pitch < 4096 &&
+	   ( ( type == GL_UNSIGNED_BYTE &&
+	       cpp == 4 && format == GL_BGRA ) ||
+	     ( type == GL_UNSIGNED_INT_8_8_8_8 &&
+	       cpp == 4 && format == GL_BGRA ) ||
+	     ( type == GL_UNSIGNED_SHORT_5_6_5_REV &&
+	       cpp == 2 && format == GL_RGB ) ) ) )
+      return GL_FALSE;
+
+   return (!ctx->_ImageTransferState &&
+	   !packing->SwapBytes &&
+	   !packing->LsbFirst);
+}
+
+static GLboolean
+check_color_per_fragment_ops( const GLcontext *ctx )
+{
+   return (!(       ctx->Color.AlphaEnabled ||
+		    ctx->Depth.Test ||
+		    ctx->Fog.Enabled ||
+		    ctx->Scissor.Enabled ||
+		    ctx->Stencil.Enabled ||
+		    !ctx->Color.ColorMask[0] ||
+		    !ctx->Color.ColorMask[1] ||
+		    !ctx->Color.ColorMask[2] ||
+		    !ctx->Color.ColorMask[3] ||
+		    ctx->Color.ColorLogicOpEnabled ||
+		    ctx->Texture.Unit[0]._ReallyEnabled ||
+		    ctx->Depth.OcclusionTest
+           ) &&
+	   ctx->Current.RasterPosValid &&
+	   ctx->Pixel.ZoomX == 1.0F &&
+	   (ctx->Pixel.ZoomY == 1.0F || ctx->Pixel.ZoomY == -1.0F));
+}
+
+static GLboolean
+check_depth_per_fragment_ops( const GLcontext *ctx )
+{
+   return ( ctx->Current.RasterPosValid &&
+	    ctx->Color.ColorMask[RCOMP] == 0 &&
+	    ctx->Color.ColorMask[BCOMP] == 0 &&
+	    ctx->Color.ColorMask[GCOMP] == 0 &&
+	    ctx->Color.ColorMask[ACOMP] == 0 &&
+	    ctx->Pixel.ZoomX == 1.0F &&
+	    ( ctx->Pixel.ZoomY == 1.0F || ctx->Pixel.ZoomY == -1.0F ) );
+}
+
+/* In addition to the requirements for depth:
+ */
+#if defined(MESA_packed_depth_stencil)
+static GLboolean
+check_stencil_per_fragment_ops( const GLcontext *ctx )
+{
+   return ( !ctx->Pixel.IndexShift &&
+	    !ctx->Pixel.IndexOffset );
+}
+#endif
+
+
+static GLboolean
+clip_pixelrect( const GLcontext *ctx,
+		const GLframebuffer *buffer,
+		GLint *x, GLint *y,
+		GLsizei *width, GLsizei *height,
+		GLint *skipPixels, GLint *skipRows,
+		GLint *size )
+{
+   mgaContextPtr mmesa = MGA_CONTEXT(ctx);
+
+   *width = MIN2(*width, MAX_WIDTH); /* redundant? */
+
+   /* left clipping */
+   if (*x < buffer->_Xmin) {
+      *skipPixels += (buffer->_Xmin - *x);
+      *width -= (buffer->_Xmin - *x);
+      *x = buffer->_Xmin;
+   }
+
+   /* right clipping */
+   if (*x + *width > buffer->_Xmax)
+      *width -= (*x + *width - buffer->_Xmax - 1);
+
+   if (*width <= 0)
+      return GL_FALSE;
+
+   /* bottom clipping */
+   if (*y < buffer->_Ymin) {
+      *skipRows += (buffer->_Ymin - *y);
+      *height -= (buffer->_Ymin - *y);
+      *y = buffer->_Ymin;
+   }
+
+   /* top clipping */
+   if (*y + *height > buffer->_Ymax)
+      *height -= (*y + *height - buffer->_Ymax - 1);
+
+   if (*height <= 0)
+      return GL_FALSE;
+
+   *size = ((*y + *height - 1) * mmesa->mgaScreen->frontPitch +
+	    (*x + *width - 1) * mmesa->mgaScreen->cpp);
+
+   return GL_TRUE;
+}
+
+static GLboolean
+mgaTryReadPixels( GLcontext *ctx,
+		  GLint x, GLint y, GLsizei width, GLsizei height,
+		  GLenum format, GLenum type,
+		  const struct gl_pixelstore_attrib *pack,
+		  GLvoid *pixels )
+{
+   mgaContextPtr mmesa = MGA_CONTEXT(ctx);
+   GLint size, skipPixels, skipRows;
+   GLint pitch = pack->RowLength ? pack->RowLength : width;
+   GLboolean ok;
+
+   GLuint planemask;
+   GLuint source;
+#if 0
+   drmMGABlit blit;
+   GLuint dest;
+   GLint source_pitch, dest_pitch;
+   GLint delta_sx, delta_sy;
+   GLint delta_dx, delta_dy;
+   GLint blit_height, ydir;
+#endif
+
+   if (!clip_pixelrect(ctx, ctx->ReadBuffer,
+		       &x, &y, &width, &height,
+		       &skipPixels, &skipRows, &size)) {
+      return GL_TRUE;
+   }
+
+   /* Only accelerate reading to agp buffers.
+    */
+   if ( !IS_AGP_MEM(mmesa, (char *)pixels) ||
+	!IS_AGP_MEM(mmesa, (char *)pixels + size) )
+      return GL_FALSE;
+
+   switch (format) {
+#if defined(MESA_packed_depth_stencil)
+   case GL_DEPTH_STENCIL_MESA:
+      ok = check_depth_stencil_24_8(ctx, type, pack, pixels, size, pitch);
+      planemask = ~0;
+      source = mmesa->mgaScreen->depthOffset;
+      break;
+#endif
+
+   case GL_DEPTH_COMPONENT:
+      ok = check_depth(ctx, type, pack, pixels, size, pitch);
+
+      /* Can't accelerate at this depth -- planemask does the wrong
+       * thing; it doesn't clear the low order bits in the
+       * destination, instead it leaves them untouched.
+       *
+       * Could get the acclerator to solid fill the destination with
+       * zeros first...  Or get the cpu to do it...
+       */
+      if (ctx->Visual.depthBits == 24)
+	 return GL_FALSE;
+
+      planemask = ~0;
+      source = mmesa->mgaScreen->depthOffset;
+      break;
+
+   case GL_RGB:
+   case GL_BGRA:
+      ok = check_color(ctx, type, format, pack, pixels, size, pitch);
+      planemask = ~0;
+      source = (mmesa->draw_buffer == MGA_FRONT ?
+		mmesa->mgaScreen->frontOffset :
+		mmesa->mgaScreen->backOffset);
+      break;
+
+   default:
+      return GL_FALSE;
+   }
+
+   if (!ok) {
+      return GL_FALSE;
+   }
+
+
+   LOCK_HARDWARE( mmesa );
+
+#if 0
+   {
+      __DRIdrawablePrivate *dPriv = mmesa->driDrawable;
+      int nbox, retcode, i;
+
+      UPDATE_LOCK( mmesa, DRM_LOCK_FLUSH | DRM_LOCK_QUIESCENT );
+
+      if (mmesa->dirty_cliprects & MGA_FRONT)
+	 mgaUpdateRects( mmesa, MGA_FRONT );
+
+      nbox = dPriv->numClipRects;
+
+      y = dPriv->h - y - height;
+      x += mmesa->drawX;
+      y += mmesa->drawY;
+
+      dest = ((mmesa->mgaScreen->agp.handle + AGP_OFFSET(mmesa, pixels)) |
+	      DO_dstmap_sys | DO_dstacc_agp);
+      source_pitch = mmesa->mgaScreen->frontPitch / mmesa->mgaScreen->cpp;
+      dest_pitch = pitch;
+      delta_sx = 0;
+      delta_sy = 0;
+      delta_dx = -x;
+      delta_dy = -y;
+      blit_height = 2*y + height;
+      ydir = -1;
+
+      if (0) fprintf(stderr, "XX doing readpixel blit src_pitch %d dst_pitch %d\n",
+		     source_pitch, dest_pitch);
+
+
+
+      for (i = 0 ; i < nbox ; )
+      {
+	 int nr = MIN2(i + MGA_NR_SAREA_CLIPRECTS, dPriv->numClipRects);
+	 XF86DRIClipRectRec *box = dPriv->pClipRects;
+	 drm_clip_rect_t *b = mmesa->sarea->boxes;
+	 int n = 0;
+
+	 for ( ; i < nr ; i++) {
+	    GLint bx = box[i].x1;
+	    GLint by = box[i].y1;
+	    GLint bw = box[i].x2 - bx;
+	    GLint bh = box[i].y2 - by;
+
+	    if (bx < x) bw -= x - bx, bx = x;
+	    if (by < y) bh -= y - by, by = y;
+	    if (bx + bw > x + width) bw = x + width - bx;
+	    if (by + bh > y + height) bh = y + height - by;
+	    if (bw <= 0) continue;
+	    if (bh <= 0) continue;
+
+	    b->x1 = bx;
+	    b->y1 = by;
+	    b->x2 = bx + bw;
+	    b->y2 = by + bh;
+	    b++;
+	    n++;
+	 }
+
+	 mmesa->sarea->nbox = n;
+
+	 if (n && (retcode = drmCommandWrite( mmesa->driFd, DRM_MGA_BLIT,
+                                              &blit, sizeof(drmMGABlit)))) {
+	    fprintf(stderr, "blit ioctl failed, retcode = %d\n", retcode);
+	    UNLOCK_HARDWARE( mmesa );
+	    exit(1);
+	 }
+      }
+
+      UPDATE_LOCK( mmesa, DRM_LOCK_FLUSH | DRM_LOCK_QUIESCENT );
+   }
+#endif
+
+   UNLOCK_HARDWARE( mmesa );
+
+   return GL_TRUE;
+}
+
+static void
+mgaDDReadPixels( GLcontext *ctx,
+		 GLint x, GLint y, GLsizei width, GLsizei height,
+		 GLenum format, GLenum type,
+		 const struct gl_pixelstore_attrib *pack,
+		 GLvoid *pixels )
+{
+   if (!mgaTryReadPixels( ctx, x, y, width, height, format, type, pack, pixels))
+      _swrast_ReadPixels( ctx, x, y, width, height, format, type, pack, pixels);
+}
+
+
+
+
+static void do_draw_pix( GLcontext *ctx,
+			 GLint x, GLint y, GLsizei width, GLsizei height,
+			 GLint pitch,
+			 const void *pixels,
+			 GLuint dest, GLuint planemask)
+{
+#if 0
+   mgaContextPtr mmesa = MGA_CONTEXT(ctx);
+   drmMGABlit blit;
+   __DRIdrawablePrivate *dPriv = mmesa->driDrawable;
+   XF86DRIClipRectPtr pbox = dPriv->pClipRects;
+   int nbox = dPriv->numClipRects;
+   int retcode, i;
+
+   y = dPriv->h - y - height;
+   x += mmesa->drawX;
+   y += mmesa->drawY;
+
+   blit.dest = dest;
+   blit.planemask = planemask;
+   blit.source = ((mmesa->mgaScreen->agp.handle + AGP_OFFSET(mmesa, pixels))
+		  | SO_srcmap_sys | SO_srcacc_agp);
+   blit.dest_pitch = mmesa->mgaScreen->frontPitch / mmesa->mgaScreen->cpp;
+   blit.source_pitch = pitch;
+   blit.delta_sx = -x;
+   blit.delta_sy = -y;
+   blit.delta_dx = 0;
+   blit.delta_dy = 0;
+   if (ctx->Pixel.ZoomY == -1) {
+      blit.height = height;
+      blit.ydir = 1;
+   } else {
+      blit.height = height;
+      blit.ydir = -1;
+   }
+
+   if (0) fprintf(stderr,
+		  "doing drawpixel blit src_pitch %d dst_pitch %d\n",
+		  blit.source_pitch, blit.dest_pitch);
+
+   for (i = 0 ; i < nbox ; )
+   {
+      int nr = MIN2(i + MGA_NR_SAREA_CLIPRECTS, dPriv->numClipRects);
+      XF86DRIClipRectRec *box = mmesa->pClipRects;
+      drm_clip_rect_t *b = mmesa->sarea->boxes;
+      int n = 0;
+
+      for ( ; i < nr ; i++) {
+	 GLint bx = box[i].x1;
+	 GLint by = box[i].y1;
+	 GLint bw = box[i].x2 - bx;
+	 GLint bh = box[i].y2 - by;
+
+	 if (bx < x) bw -= x - bx, bx = x;
+	 if (by < y) bh -= y - by, by = y;
+	 if (bx + bw > x + width) bw = x + width - bx;
+	 if (by + bh > y + height) bh = y + height - by;
+	 if (bw <= 0) continue;
+	 if (bh <= 0) continue;
+
+	 b->x1 = bx;
+	 b->y1 = by;
+	 b->x2 = bx + bw;
+	 b->y2 = by + bh;
+	 b++;
+	 n++;
+      }
+
+      mmesa->sarea->nbox = n;
+
+      if (n && (retcode = drmCommandWrite( mmesa->driFd, DRM_MGA_BLIT,
+                                              &blit, sizeof(drmMGABlit)))) {
+	 fprintf(stderr, "blit ioctl failed, retcode = %d\n", retcode);
+	 UNLOCK_HARDWARE( mmesa );
+	 exit(1);
+      }
+   }
+#endif
+}
+
+
+
+
+static GLboolean
+mgaTryDrawPixels( GLcontext *ctx,
+		  GLint x, GLint y, GLsizei width, GLsizei height,
+		  GLenum format, GLenum type,
+		  const struct gl_pixelstore_attrib *unpack,
+		  const GLvoid *pixels )
+{
+   mgaContextPtr mmesa = MGA_CONTEXT(ctx);
+   GLint size, skipPixels, skipRows;
+   GLint pitch = unpack->RowLength ? unpack->RowLength : width;
+   GLuint dest, planemask;
+   GLuint cpp = mmesa->mgaScreen->cpp;
+
+   if (!clip_pixelrect(ctx, ctx->DrawBuffer,
+		       &x, &y, &width, &height,
+		       &skipPixels, &skipRows, &size)) {
+      return GL_TRUE;
+   }
+
+
+   switch (format) {
+#if defined(MESA_packed_depth_stencil)
+   case GL_DEPTH_STENCIL_MESA:
+      dest = mmesa->mgaScreen->depthOffset;
+      planemask = ~0;
+      if (!check_depth_stencil_24_8(ctx, type, unpack, pixels, size, pitch) ||
+	  !check_depth_per_fragment_ops(ctx) ||
+	  !check_stencil_per_fragment_ops(ctx))
+	 return GL_FALSE;
+      break;
+#endif
+
+   case GL_DEPTH_COMPONENT:
+      dest = mmesa->mgaScreen->depthOffset;
+
+      if (ctx->Visual.depthBits == 24)
+	 planemask = ~0xff;
+      else
+	 planemask = ~0;
+
+      if (!check_depth(ctx, type, unpack, pixels, size, pitch) ||
+	  !check_depth_per_fragment_ops(ctx))
+	 return GL_FALSE;
+      break;
+
+   case GL_RGB:
+   case GL_BGRA:
+      dest = (mmesa->draw_buffer == MGA_FRONT ?
+	      mmesa->mgaScreen->frontOffset :
+	      mmesa->mgaScreen->backOffset);
+
+      planemask = mgaPackColor(cpp,
+			       ctx->Color.ColorMask[RCOMP],
+			       ctx->Color.ColorMask[GCOMP],
+			       ctx->Color.ColorMask[BCOMP],
+			       ctx->Color.ColorMask[ACOMP]);
+
+      if (cpp == 2)
+	 planemask |= planemask << 16;
+
+      if (!check_color(ctx, type, format, unpack, pixels, size, pitch)) {
+	 return GL_FALSE;
+      }
+      if (!check_color_per_fragment_ops(ctx)) {
+	 return GL_FALSE;
+      }
+      break;
+
+   default:
+      return GL_FALSE;
+   }
+
+   LOCK_HARDWARE_QUIESCENT( mmesa );
+
+   if (mmesa->dirty_cliprects & MGA_FRONT)
+      mgaUpdateRects( mmesa, MGA_FRONT );
+
+   if ( IS_AGP_MEM(mmesa, (char *)pixels) &&
+	IS_AGP_MEM(mmesa, (char *)pixels + size) )
+   {
+      do_draw_pix( ctx, x, y, width, height, pitch, pixels,
+		   dest, planemask );
+      UPDATE_LOCK( mmesa, DRM_LOCK_FLUSH | DRM_LOCK_QUIESCENT );
+   }
+   else
+   {
+      /* Pixels is in regular memory -- get dma buffers and perform
+       * upload through them.
+       */
+/*        drmBufPtr buf = mgaGetBufferLocked(mmesa); */
+      GLuint bufferpitch = (width*cpp+31)&~31;
+
+      char *address = 0; /*  mmesa->mgaScreen->agp.map; */
+
+      do {
+/*  	 GLuint rows = MIN2( height, MGA_DMA_BUF_SZ / bufferpitch ); */
+	 GLuint rows = height;
+
+
+	 if (0) fprintf(stderr, "trying to upload %d rows (pitch %d)\n",
+			rows, bufferpitch);
+
+	 /* The texture conversion code is so slow that there is only
+	  * negligble speedup when the buffers/images don't exactly
+	  * match:
+	  */
+#if 0
+	 if (cpp == 2) {
+	    if (!_mesa_convert_texsubimage2d( MESA_FORMAT_RGB565,
+					      0, 0, width, rows,
+					      bufferpitch, format, type,
+					      unpack, pixels, address )) {
+/*  	       mgaReleaseBufLocked( mmesa, buf ); */
+	       UNLOCK_HARDWARE(mmesa);
+	       return GL_FALSE;
+	    }
+	 } else {
+	    if (!_mesa_convert_texsubimage2d( MESA_FORMAT_ARGB8888,
+					      0, 0, width, rows,
+					      bufferpitch, format, type,
+					      unpack, pixels, address )) {
+/*  	       mgaReleaseBufLocked( mmesa, buf ); */
+	       UNLOCK_HARDWARE(mmesa);
+	       return GL_FALSE;
+	    }
+	 }
+#else
+	 memcpy( address, pixels, rows*bufferpitch );
+#endif
+
+	 do_draw_pix( ctx, x, y, width, rows,
+		      bufferpitch/cpp, address, dest, planemask );
+
+	 /* Fix me -- use multiple buffers to avoid flush.
+	  */
+	 UPDATE_LOCK( mmesa, DRM_LOCK_FLUSH | DRM_LOCK_QUIESCENT );
+
+	 pixels = (void *)((char *) pixels + rows * pitch);
+	 height -= rows;
+	 y += rows;
+      } while (height);
+
+/*        mgaReleaseBufLocked( mmesa, buf ); */
+   }
+
+   UNLOCK_HARDWARE( mmesa );
+   mmesa->dirty |= MGA_UPLOAD_CLIPRECTS;
+
+   return GL_TRUE;
+}
+
+static void
+mgaDDDrawPixels( GLcontext *ctx,
+		 GLint x, GLint y, GLsizei width, GLsizei height,
+		 GLenum format, GLenum type,
+		 const struct gl_pixelstore_attrib *unpack,
+		 const GLvoid *pixels )
+{
+   if (!mgaTryDrawPixels( ctx, x, y, width, height, format, type,
+			  unpack, pixels ))
+      _swrast_DrawPixels( ctx, x, y, width, height, format, type,
+			  unpack, pixels );
+}
+
+
+
+/* Stub functions - not a real allocator, always returns pointer to
+ * the same block of agp space which isn't used for anything else at
+ * present.
+ */
+#if defined(MESA_hacked_agp_allocator)
+static void mgaDDFreeAgpMemory( GLcontext *ctx, void *ptr )
+{
+   (void) ptr;
+}
+
+static void *mgaDDAllocateAgpMemory( GLcontext *ctx, GLsizei size )
+{
+   mgaContextPtr mmesa = MGA_CONTEXT(ctx);
+
+   if (size < mmesa->mgaScreen->textureSize[MGA_AGP_HEAP])
+      return mmesa->mgaScreen->texVirtual[MGA_AGP_HEAP];
+   else
+      return 0;
+}
+
+static GLint mgaDDGetAgpOffset( GLcontext *ctx, const void *ptr )
+{
+   mgaContextPtr mmesa = MGA_CONTEXT(ctx);
+
+   if (!IS_AGP_MEM(mmesa, ptr))
+      return -1;
+
+   return AGP_OFFSET(mmesa, ptr);
+}
+#endif
+
+
+void mgaDDInitPixelFuncs( GLcontext *ctx )
+{
+#if defined (MESA_experimetal_agp_allocator)
+   ctx->Driver.AllocateAgpMemory = mgaDDAllocateAgpMemory;
+   ctx->Driver.GetAgpOffset = mgaDDGetAgpOffset;
+   ctx->Driver.FreeAgpMemory = mgaDDFreeAgpMemory;
+#endif
+
+   /* Pixel path fallbacks.
+    */
+   ctx->Driver.Accum = _swrast_Accum;
+   ctx->Driver.Bitmap = _swrast_Bitmap;
+   ctx->Driver.CopyPixels = _swrast_CopyPixels;
+   ctx->Driver.DrawPixels = _swrast_DrawPixels;
+   ctx->Driver.ReadPixels = _swrast_ReadPixels;
+
+   if (getenv("MGA_BLIT_PIXELS")) {
+      ctx->Driver.ReadPixels = mgaDDReadPixels; /* requires agp dest */
+      ctx->Driver.DrawPixels = mgaDDDrawPixels; /* works with agp/normal mem */
+   }
+}