src/mesa/drivers/dri/mga/mgapixel.c

   1 /*
   2  * Copyright 2000 Compaq Computer Inc. and VA Linux Systems, Inc.
   3  * All Rights Reserved.
   4  *
   5  * Permission is hereby granted, free of charge, to any person obtaining a
   6  * copy of this software and associated documentation files (the "Software"),
   7  * to deal in the Software without restriction, including without limitation
   8  * on the rights to use, copy, modify, merge, publish, distribute, sub
   9  * license, and/or sell copies of the Software, and to permit persons to whom
  10  * the Software is furnished to do so, subject to the following conditions:
  11  *
  12  * The above copyright notice and this permission notice (including the next
  13  * paragraph) shall be included in all copies or substantial portions of the
  14  * Software.
  15  *
  16  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  17  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  18  * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.  IN NO EVENT SHALL
  19  * VA LINUX SYSTEMS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
  20  * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
  21  * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
  22  * OTHER DEALINGS IN THE SOFTWARE.
  23  */
  24
  25 /**
  26  * \file mgapixel.c
  27  * Implement framebuffer pixel operations for MGA.
  28  *
  29  * \todo
  30  * Someday the accelerated \c glReadPixels and \c glDrawPixels paths need to
  31  * be resurrected.  They are currently ifdef'ed out because they don't seem
  32  * to work and they only get activated some very rare circumstances.
  33  *
  34  * \author Keith Whitwell <keith@tungstengraphics.com>
  35  * \author Gareth Hughes <gareth@valinux.com>
  36  */
  37
  38 #include "main/mtypes.h"
  39 #include "main/macros.h"
  40 #include "mgadd.h"
  41 #include "mgacontext.h"
  42 #include "mgaioctl.h"
  43 #include "mgapixel.h"
  44 #include "mgastate.h"
  45
  46 #include "swrast/swrast.h"
  47 #include "main/imports.h"
  48
  49 #if 0
  50 #define IS_AGP_MEM( mmesa, p )                                            \
  51    ((unsigned long)mmesa->mgaScreen->buffers.map <= ((unsigned long)p) && \
  52     (unsigned long)mmesa->mgaScreen->buffers.map +                        \
  53     (unsigned long)mmesa->mgaScreen->buffers.size > ((unsigned long)p))
  54 #define AGP_OFFSET( mmesa, p )                                            \
  55      (((unsigned long)p) - (unsigned long)mmesa->mgaScreen->buffers.map)
  56
  57
  58 static GLboolean
  59 check_depth_stencil_24_8( const struct gl_context *ctx, GLenum type,
  60                           const struct gl_pixelstore_attrib *packing,
  61                           const void *pixels, GLint sz,
  62                           GLint pitch )
  63 {
  64    mgaContextPtr mmesa = MGA_CONTEXT(ctx);
  65
  66    return ( type == GL_UNSIGNED_INT_24_8 &&
  67             ctx->Visual->DepthBits == 24 &&
  68             ctx->Visual->StencilBits == 8 &&
  69             mmesa->mgaScreen->cpp == 4 &&
  70             mmesa->hw_stencil &&
  71             !ctx->Pixel.IndexShift &&
  72             !ctx->Pixel.IndexOffset &&
  73             !ctx->Pixel.MapStencilFlag &&
  74             ctx->Pixel.DepthBias == 0.0 &&
  75             ctx->Pixel.DepthScale == 1.0 &&
  76             !packing->SwapBytes &&
  77             pitch % 32 == 0 &&
  78             pitch < 4096 );
  79 }
  80
  81
  82 static GLboolean
  83 check_depth( const struct gl_context *ctx, GLenum type,
  84              const struct gl_pixelstore_attrib *packing,
  85              const void *pixels, GLint sz, GLint pitch )
  86 {
  87    mgaContextPtr mmesa = MGA_CONTEXT(ctx);
  88
  89    if ( IS_AGP_MEM( mmesa, pixels ) &&
  90         !( ( type == GL_UNSIGNED_INT && mmesa->mgaScreen->cpp == 4 ) ||
  91            ( type == GL_UNSIGNED_SHORT && mmesa->mgaScreen->cpp == 2 ) ) )
  92       return GL_FALSE;
  93
  94    return ( ctx->Pixel.DepthBias == 0.0 &&
  95             ctx->Pixel.DepthScale == 1.0 &&
  96             !packing->SwapBytes &&
  97             pitch % 32 == 0 &&
  98             pitch < 4096 );
  99 }
 100
 101
 102 static GLboolean
 103 check_color( const struct gl_context *ctx, GLenum type, GLenum format,
 104              const struct gl_pixelstore_attrib *packing,
 105              const void *pixels, GLint sz, GLint pitch )
 106 {
 107    mgaContextPtr mmesa = MGA_CONTEXT(ctx);
 108    GLuint cpp = mmesa->mgaScreen->cpp;
 109
 110    /* Can't do conversions on agp reads/draws.
 111     */
 112    if ( IS_AGP_MEM( mmesa, pixels ) &&
 113         !( pitch % 32 == 0 && pitch < 4096 &&
 114            ( ( type == GL_UNSIGNED_BYTE &&
 115                cpp == 4 && format == GL_BGRA ) ||
 116              ( type == GL_UNSIGNED_INT_8_8_8_8 &&
 117                cpp == 4 && format == GL_BGRA ) ||
 118              ( type == GL_UNSIGNED_SHORT_5_6_5_REV &&
 119                cpp == 2 && format == GL_RGB ) ) ) )
 120       return GL_FALSE;
 121
 122    return (!ctx->_ImageTransferState &&
 123            !packing->SwapBytes &&
 124            !packing->LsbFirst);
 125 }
 126
 127 static GLboolean
 128 check_color_per_fragment_ops( const struct gl_context *ctx )
 129 {
 130    return (!(       ctx->Color.AlphaEnabled ||
 131                     ctx->Depth.Test ||
 132                     ctx->Fog.Enabled ||
 133                     ctx->Scissor.Enabled ||
 134                     ctx->Stencil._Enabled ||
 135                     !ctx->Color.ColorMask[0][0] ||
 136                     !ctx->Color.ColorMask[0][1] ||
 137                     !ctx->Color.ColorMask[0][2] ||
 138                     !ctx->Color.ColorMask[0][3] ||
 139                     ctx->Color.ColorLogicOpEnabled ||
 140                     ctx->Texture._EnabledUnits
 141            ) &&
 142            ctx->Current.RasterPosValid &&
 143            ctx->Pixel.ZoomX == 1.0F &&
 144            (ctx->Pixel.ZoomY == 1.0F || ctx->Pixel.ZoomY == -1.0F));
 145 }
 146
 147 static GLboolean
 148 check_depth_per_fragment_ops( const struct gl_context *ctx )
 149 {
 150    return ( ctx->Current.RasterPosValid &&
 151             ctx->Color.ColorMask[0][RCOMP] == 0 &&
 152             ctx->Color.ColorMask[0][BCOMP] == 0 &&
 153             ctx->Color.ColorMask[0][GCOMP] == 0 &&
 154             ctx->Color.ColorMask[0][ACOMP] == 0 &&
 155             ctx->Pixel.ZoomX == 1.0F &&
 156             ( ctx->Pixel.ZoomY == 1.0F || ctx->Pixel.ZoomY == -1.0F ) );
 157 }
 158
 159 /* In addition to the requirements for depth:
 160  */
 161 #if defined(MESA_packed_depth_stencil)
 162 static GLboolean
 163 check_stencil_per_fragment_ops( const struct gl_context *ctx )
 164 {
 165    return ( !ctx->Pixel.IndexShift &&
 166             !ctx->Pixel.IndexOffset );
 167 }
 168 #endif
 169
 170
 171 static GLboolean
 172 clip_pixelrect( const struct gl_context *ctx,
 173                 const struct gl_framebuffer *buffer,
 174                 GLint *x, GLint *y,
 175                 GLsizei *width, GLsizei *height,
 176                 GLint *skipPixels, GLint *skipRows,
 177                 GLint *size )
 178 {
 179    mgaContextPtr mmesa = MGA_CONTEXT(ctx);
 180
 181    *width = MIN2(*width, MAX_WIDTH); /* redundant? */
 182
 183    /* left clipping */
 184    if (*x < buffer->_Xmin) {
 185       *skipPixels += (buffer->_Xmin - *x);
 186       *width -= (buffer->_Xmin - *x);
 187       *x = buffer->_Xmin;
 188    }
 189
 190    /* right clipping */
 191    if (*x + *width > buffer->_Xmax)
 192       *width -= (*x + *width - buffer->_Xmax - 1);
 193
 194    if (*width <= 0)
 195       return GL_FALSE;
 196
 197    /* bottom clipping */
 198    if (*y < buffer->_Ymin) {
 199       *skipRows += (buffer->_Ymin - *y);
 200       *height -= (buffer->_Ymin - *y);
 201       *y = buffer->_Ymin;
 202    }
 203
 204    /* top clipping */
 205    if (*y + *height > buffer->_Ymax)
 206       *height -= (*y + *height - buffer->_Ymax - 1);
 207
 208    if (*height <= 0)
 209       return GL_FALSE;
 210
 211    *size = ((*y + *height - 1) * mmesa->mgaScreen->frontPitch +
 212             (*x + *width - 1) * mmesa->mgaScreen->cpp);
 213
 214    return GL_TRUE;
 215 }
 216
 217 static GLboolean
 218 mgaTryReadPixels( struct gl_context *ctx,
 219                   GLint x, GLint y, GLsizei width, GLsizei height,
 220                   GLenum format, GLenum type,
 221                   const struct gl_pixelstore_attrib *pack,
 222                   GLvoid *pixels )
 223 {
 224    mgaContextPtr mmesa = MGA_CONTEXT(ctx);
 225    GLint size, skipPixels, skipRows;
 226    GLint pitch = pack->RowLength ? pack->RowLength : width;
 227    GLboolean ok;
 228
 229    GLuint planemask;
 230    GLuint source;
 231 #if 0
 232    drmMGABlit blit;
 233    GLuint dest;
 234    GLint source_pitch, dest_pitch;
 235    GLint delta_sx, delta_sy;
 236    GLint delta_dx, delta_dy;
 237    GLint blit_height, ydir;
 238 #endif
 239
 240    if (!clip_pixelrect(ctx, ctx->ReadBuffer,
 241                        &x, &y, &width, &height,
 242                        &skipPixels, &skipRows, &size)) {
 243       return GL_TRUE;
 244    }
 245
 246    /* Only accelerate reading to agp buffers.
 247     */
 248    if ( !IS_AGP_MEM(mmesa, (char *)pixels) ||
 249         !IS_AGP_MEM(mmesa, (char *)pixels + size) )
 250       return GL_FALSE;
 251
 252    switch (format) {
 253    case GL_DEPTH_STENCIL:
 254       ok = check_depth_stencil_24_8(ctx, type, pack, pixels, size, pitch);
 255       planemask = ~0;
 256       source = mmesa->mgaScreen->depthOffset;
 257       break;
 258
 259    case GL_DEPTH_COMPONENT:
 260       ok = check_depth(ctx, type, pack, pixels, size, pitch);
 261
 262       /* Can't accelerate at this depth -- planemask does the wrong
 263        * thing; it doesn't clear the low order bits in the
 264        * destination, instead it leaves them untouched.
 265        *
 266        * Could get the acclerator to solid fill the destination with
 267        * zeros first...  Or get the cpu to do it...
 268        */
 269       if (ctx->Visual.depthBits == 24)
 270          return GL_FALSE;
 271
 272       planemask = ~0;
 273       source = mmesa->mgaScreen->depthOffset;
 274       break;
 275
 276    case GL_RGB:
 277    case GL_BGRA:
 278       ok = check_color(ctx, type, format, pack, pixels, size, pitch);
 279       planemask = ~0;
 280       source = (mmesa->draw_buffer == MGA_FRONT ?
 281                 mmesa->mgaScreen->frontOffset :
 282                 mmesa->mgaScreen->backOffset);
 283       break;
 284
 285    default:
 286       return GL_FALSE;
 287    }
 288
 289    if (!ok) {
 290       return GL_FALSE;
 291    }
 292
 293
 294    LOCK_HARDWARE( mmesa );
 295
 296 #if 0
 297    {
 298       __DRIdrawable *dPriv = mmesa->driDrawable;
 299       int nbox, retcode, i;
 300
 301       UPDATE_LOCK( mmesa, DRM_LOCK_FLUSH | DRM_LOCK_QUIESCENT );
 302
 303       if (mmesa->dirty_cliprects & MGA_FRONT)
 304          mgaUpdateRects( mmesa, MGA_FRONT );
 305
 306       nbox = dPriv->numClipRects;
 307
 308       y = dPriv->h - y - height;
 309       x += mmesa->drawX;
 310       y += mmesa->drawY;
 311
 312       dest = ((mmesa->mgaScreen->agp.handle + AGP_OFFSET(mmesa, pixels)) |
 313               DO_dstmap_sys | DO_dstacc_agp);
 314       source_pitch = mmesa->mgaScreen->frontPitch / mmesa->mgaScreen->cpp;
 315       dest_pitch = pitch;
 316       delta_sx = 0;
 317       delta_sy = 0;
 318       delta_dx = -x;
 319       delta_dy = -y;
 320       blit_height = 2*y + height;
 321       ydir = -1;
 322
 323       if (0) fprintf(stderr, "XX doing readpixel blit src_pitch %d dst_pitch %d\n",
 324                      source_pitch, dest_pitch);
 325
 326
 327
 328       for (i = 0 ; i < nbox ; )
 329       {
 330          int nr = MIN2(i + MGA_NR_SAREA_CLIPRECTS, dPriv->numClipRects);
 331          drm_clip_rect_t *box = dPriv->pClipRects;
 332          drm_clip_rect_t *b = mmesa->sarea->boxes;
 333          int n = 0;
 334
 335          for ( ; i < nr ; i++) {
 336             GLint bx = box[i].x1;
 337             GLint by = box[i].y1;
 338             GLint bw = box[i].x2 - bx;
 339             GLint bh = box[i].y2 - by;
 340
 341             if (bx < x) bw -= x - bx, bx = x;
 342             if (by < y) bh -= y - by, by = y;
 343             if (bx + bw > x + width) bw = x + width - bx;
 344             if (by + bh > y + height) bh = y + height - by;
 345             if (bw <= 0) continue;
 346             if (bh <= 0) continue;
 347
 348             b->x1 = bx;
 349             b->y1 = by;
 350             b->x2 = bx + bw;
 351             b->y2 = by + bh;
 352             b++;
 353             n++;
 354          }
 355
 356          mmesa->sarea->nbox = n;
 357
 358          if (n && (retcode = drmCommandWrite( mmesa->driFd, DRM_MGA_BLIT,
 359                                               &blit, sizeof(drmMGABlit)))) {
 360             fprintf(stderr, "blit ioctl failed, retcode = %d\n", retcode);
 361             UNLOCK_HARDWARE( mmesa );
 362             exit(1);
 363          }
 364       }
 365
 366       UPDATE_LOCK( mmesa, DRM_LOCK_FLUSH | DRM_LOCK_QUIESCENT );
 367    }
 368 #endif
 369
 370    UNLOCK_HARDWARE( mmesa );
 371
 372    return GL_TRUE;
 373 }
 374
 375 static void
 376 mgaDDReadPixels( struct gl_context *ctx,
 377                  GLint x, GLint y, GLsizei width, GLsizei height,
 378                  GLenum format, GLenum type,
 379                  const struct gl_pixelstore_attrib *pack,
 380                  GLvoid *pixels )
 381 {
 382    if (!mgaTryReadPixels( ctx, x, y, width, height, format, type, pack, pixels))
 383       _swrast_ReadPixels( ctx, x, y, width, height, format, type, pack, pixels);
 384 }
 385
 386
 387
 388
 389 static void do_draw_pix( struct gl_context *ctx,
 390                          GLint x, GLint y, GLsizei width, GLsizei height,
 391                          GLint pitch,
 392                          const void *pixels,
 393                          GLuint dest, GLuint planemask)
 394 {
 395 #if 0
 396    mgaContextPtr mmesa = MGA_CONTEXT(ctx);
 397    drmMGABlit blit;
 398    __DRIdrawable *dPriv = mmesa->driDrawable;
 399    drm_clip_rect_t pbox = dPriv->pClipRects;
 400    int nbox = dPriv->numClipRects;
 401    int retcode, i;
 402
 403    y = dPriv->h - y - height;
 404    x += mmesa->drawX;
 405    y += mmesa->drawY;
 406
 407    blit.dest = dest;
 408    blit.planemask = planemask;
 409    blit.source = ((mmesa->mgaScreen->agp.handle + AGP_OFFSET(mmesa, pixels))
 410                   | SO_srcmap_sys | SO_srcacc_agp);
 411    blit.dest_pitch = mmesa->mgaScreen->frontPitch / mmesa->mgaScreen->cpp;
 412    blit.source_pitch = pitch;
 413    blit.delta_sx = -x;
 414    blit.delta_sy = -y;
 415    blit.delta_dx = 0;
 416    blit.delta_dy = 0;
 417    if (ctx->Pixel.ZoomY == -1) {
 418       blit.height = height;
 419       blit.ydir = 1;
 420    } else {
 421       blit.height = height;
 422       blit.ydir = -1;
 423    }
 424
 425    if (0) fprintf(stderr,
 426                   "doing drawpixel blit src_pitch %d dst_pitch %d\n",
 427                   blit.source_pitch, blit.dest_pitch);
 428
 429    for (i = 0 ; i < nbox ; )
 430    {
 431       int nr = MIN2(i + MGA_NR_SAREA_CLIPRECTS, dPriv->numClipRects);
 432       drm_clip_rect_t *box = mmesa->pClipRects;
 433       drm_clip_rect_t *b = mmesa->sarea->boxes;
 434       int n = 0;
 435
 436       for ( ; i < nr ; i++) {
 437          GLint bx = box[i].x1;
 438          GLint by = box[i].y1;
 439          GLint bw = box[i].x2 - bx;
 440          GLint bh = box[i].y2 - by;
 441
 442          if (bx < x) bw -= x - bx, bx = x;
 443          if (by < y) bh -= y - by, by = y;
 444          if (bx + bw > x + width) bw = x + width - bx;
 445          if (by + bh > y + height) bh = y + height - by;
 446          if (bw <= 0) continue;
 447          if (bh <= 0) continue;
 448
 449          b->x1 = bx;
 450          b->y1 = by;
 451          b->x2 = bx + bw;
 452          b->y2 = by + bh;
 453          b++;
 454          n++;
 455       }
 456
 457       mmesa->sarea->nbox = n;
 458
 459       if (n && (retcode = drmCommandWrite( mmesa->driFd, DRM_MGA_BLIT,
 460                                               &blit, sizeof(drmMGABlit)))) {
 461          fprintf(stderr, "blit ioctl failed, retcode = %d\n", retcode);
 462          UNLOCK_HARDWARE( mmesa );
 463          exit(1);
 464       }
 465    }
 466 #endif
 467 }
 468
 469
 470
 471
 472 static GLboolean
 473 mgaTryDrawPixels( struct gl_context *ctx,
 474                   GLint x, GLint y, GLsizei width, GLsizei height,
 475                   GLenum format, GLenum type,
 476                   const struct gl_pixelstore_attrib *unpack,
 477                   const GLvoid *pixels )
 478 {
 479    mgaContextPtr mmesa = MGA_CONTEXT(ctx);
 480    GLint size, skipPixels, skipRows;
 481    GLint pitch = unpack->RowLength ? unpack->RowLength : width;
 482    GLuint dest, planemask;
 483    GLuint cpp = mmesa->mgaScreen->cpp;
 484
 485    if (!clip_pixelrect(ctx, ctx->DrawBuffer,
 486                        &x, &y, &width, &height,
 487                        &skipPixels, &skipRows, &size)) {
 488       return GL_TRUE;
 489    }
 490
 491
 492    switch (format) {
 493    case GL_DEPTH_STENCIL:
 494       dest = mmesa->mgaScreen->depthOffset;
 495       planemask = ~0;
 496       if (!check_depth_stencil_24_8(ctx, type, unpack, pixels, size, pitch) ||
 497           !check_depth_per_fragment_ops(ctx) ||
 498           !check_stencil_per_fragment_ops(ctx))
 499          return GL_FALSE;
 500       break;
 501
 502    case GL_DEPTH_COMPONENT:
 503       dest = mmesa->mgaScreen->depthOffset;
 504
 505       if (ctx->Visual.depthBits == 24)
 506          planemask = ~0xff;
 507       else
 508          planemask = ~0;
 509
 510       if (!check_depth(ctx, type, unpack, pixels, size, pitch) ||
 511           !check_depth_per_fragment_ops(ctx))
 512          return GL_FALSE;
 513       break;
 514
 515    case GL_RGB:
 516    case GL_BGRA:
 517       dest = (mmesa->draw_buffer == MGA_FRONT ?
 518               mmesa->mgaScreen->frontOffset :
 519               mmesa->mgaScreen->backOffset);
 520
 521       planemask = mgaPackColor(cpp,
 522                                ctx->Color.ColorMask[0][RCOMP],
 523                                ctx->Color.ColorMask[0][GCOMP],
 524                                ctx->Color.ColorMask[0][BCOMP],
 525                                ctx->Color.ColorMask[0][ACOMP]);
 526
 527       if (cpp == 2)
 528          planemask |= planemask << 16;
 529
 530       if (!check_color(ctx, type, format, unpack, pixels, size, pitch)) {
 531          return GL_FALSE;
 532       }
 533       if (!check_color_per_fragment_ops(ctx)) {
 534          return GL_FALSE;
 535       }
 536       break;
 537
 538    default:
 539       return GL_FALSE;
 540    }
 541
 542    LOCK_HARDWARE_QUIESCENT( mmesa );
 543
 544    if (mmesa->dirty_cliprects & MGA_FRONT)
 545       mgaUpdateRects( mmesa, MGA_FRONT );
 546
 547    if ( IS_AGP_MEM(mmesa, (char *)pixels) &&
 548         IS_AGP_MEM(mmesa, (char *)pixels + size) )
 549    {
 550       do_draw_pix( ctx, x, y, width, height, pitch, pixels,
 551                    dest, planemask );
 552       UPDATE_LOCK( mmesa, DRM_LOCK_FLUSH | DRM_LOCK_QUIESCENT );
 553    }
 554    else
 555    {
 556       /* Pixels is in regular memory -- get dma buffers and perform
 557        * upload through them.
 558        */
 559 /*        drmBufPtr buf = mgaGetBufferLocked(mmesa); */
 560       GLuint bufferpitch = (width*cpp+31)&~31;
 561
 562       char *address = 0; /*  mmesa->mgaScreen->agp.map; */
 563
 564       do {
 565 /*       GLuint rows = MIN2( height, MGA_DMA_BUF_SZ / bufferpitch ); */
 566          GLuint rows = height;
 567
 568
 569          if (0) fprintf(stderr, "trying to upload %d rows (pitch %d)\n",
 570                         rows, bufferpitch);
 571
 572          /* The texture conversion code is so slow that there is only
 573           * negligble speedup when the buffers/images don't exactly
 574           * match:
 575           */
 576 #if 0
 577          if (cpp == 2) {
 578             if (!_mesa_convert_texsubimage2d( MESA_FORMAT_RGB565,
 579                                               0, 0, width, rows,
 580                                               bufferpitch, format, type,
 581                                               unpack, pixels, address )) {
 582 /*             mgaReleaseBufLocked( mmesa, buf ); */
 583                UNLOCK_HARDWARE(mmesa);
 584                return GL_FALSE;
 585             }
 586          } else {
 587             if (!_mesa_convert_texsubimage2d( MESA_FORMAT_ARGB8888,
 588                                               0, 0, width, rows,
 589                                               bufferpitch, format, type,
 590                                               unpack, pixels, address )) {
 591 /*             mgaReleaseBufLocked( mmesa, buf ); */
 592                UNLOCK_HARDWARE(mmesa);
 593                return GL_FALSE;
 594             }
 595          }
 596 #else
 597          memcpy( address, pixels, rows*bufferpitch );
 598 #endif
 599
 600          do_draw_pix( ctx, x, y, width, rows,
 601                       bufferpitch/cpp, address, dest, planemask );
 602
 603          /* Fix me -- use multiple buffers to avoid flush.
 604           */
 605          UPDATE_LOCK( mmesa, DRM_LOCK_FLUSH | DRM_LOCK_QUIESCENT );
 606
 607          pixels = (void *)((char *) pixels + rows * pitch);
 608          height -= rows;
 609          y += rows;
 610       } while (height);
 611
 612 /*        mgaReleaseBufLocked( mmesa, buf ); */
 613    }
 614
 615    UNLOCK_HARDWARE( mmesa );
 616    mmesa->dirty |= MGA_UPLOAD_CLIPRECTS;
 617
 618    return GL_TRUE;
 619 }
 620
 621 static void
 622 mgaDDDrawPixels( struct gl_context *ctx,
 623                  GLint x, GLint y, GLsizei width, GLsizei height,
 624                  GLenum format, GLenum type,
 625                  const struct gl_pixelstore_attrib *unpack,
 626                  const GLvoid *pixels )
 627 {
 628    if (!mgaTryDrawPixels( ctx, x, y, width, height, format, type,
 629                           unpack, pixels ))
 630       _swrast_DrawPixels( ctx, x, y, width, height, format, type,
 631                           unpack, pixels );
 632 }
 633 #endif
 634
 635
 636 /* Stub functions - not a real allocator, always returns pointer to
 637  * the same block of agp space which isn't used for anything else at
 638  * present.
 639  */
 640 void mgaDDInitPixelFuncs( struct gl_context *ctx )
 641 {
 642 #if 0
 643    /* evidently, these functions don't always work */
 644    if (getenv("MGA_BLIT_PIXELS")) {
 645       ctx->Driver.ReadPixels = mgaDDReadPixels; /* requires agp dest */
 646       ctx->Driver.DrawPixels = mgaDDDrawPixels; /* works with agp/normal mem */
 647    }
 648 #endif
 649 }