aboutsummaryrefslogtreecommitdiff
path: root/mesalib/src/mesa/main/context.c
blob: 458d8e59b1788c30811ad35980dc12cd4a2b31d0 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
/*
 * Mesa 3-D graphics library
 *
 * Copyright (C) 1999-2007  Brian Paul   All Rights Reserved.
 * Copyright (C) 2008  VMware, 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
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * 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 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 NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS 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.
 */

/**
 * \file context.c
 * Mesa context/visual/framebuffer management functions.
 * \author Brian Paul
 */

/**
 * \mainpage Mesa Main Module
 *
 * \section MainIntroduction Introduction
 *
 * The Mesa Main module consists of all the files in the main/ directory.
 * Among the features of this module are:
 * <UL>
 * <LI> Structures to represent most GL state </LI>
 * <LI> State set/get functions </LI>
 * <LI> Display lists </LI>
 * <LI> Texture unit, object and image handling </LI>
 * <LI> Matrix and attribute stacks </LI>
 * </UL>
 *
 * Other modules are responsible for API dispatch, vertex transformation,
 * point/line/triangle setup, rasterization, vertex array caching,
 * vertex/fragment programs/shaders, etc.
 *
 *
 * \section AboutDoxygen About Doxygen
 *
 * If you're viewing this information as Doxygen-generated HTML you'll
 * see the documentation index at the top of this page.
 *
 * The first line lists the Mesa source code modules.
 * The second line lists the indexes available for viewing the documentation
 * for each module.
 *
 * Selecting the <b>Main page</b> link will display a summary of the module
 * (this page).
 *
 * Selecting <b>Data Structures</b> will list all C structures.
 *
 * Selecting the <b>File List</b> link will list all the source files in
 * the module.
 * Selecting a filename will show a list of all functions defined in that file.
 *
 * Selecting the <b>Data Fields</b> link will display a list of all
 * documented structure members.
 *
 * Selecting the <b>Globals</b> link will display a list
 * of all functions, structures, global variables and macros in the module.
 *
 */


#include "glheader.h"
#include "imports.h"
#include "accum.h"
#include "api_exec.h"
#include "api_loopback.h"
#include "arrayobj.h"
#include "attrib.h"
#include "blend.h"
#include "buffers.h"
#include "bufferobj.h"
#include "context.h"
#include "cpuinfo.h"
#include "debug.h"
#include "depth.h"
#include "dlist.h"
#include "eval.h"
#include "extensions.h"
#include "fbobject.h"
#include "feedback.h"
#include "fog.h"
#include "formats.h"
#include "framebuffer.h"
#include "hint.h"
#include "hash.h"
#include "light.h"
#include "lines.h"
#include "macros.h"
#include "matrix.h"
#include "multisample.h"
#include "performance_monitor.h"
#include "pixel.h"
#include "pixelstore.h"
#include "points.h"
#include "polygon.h"
#include "queryobj.h"
#include "syncobj.h"
#include "rastpos.h"
#include "remap.h"
#include "scissor.h"
#include "shared.h"
#include "shaderobj.h"
#include "simple_list.h"
#include "state.h"
#include "stencil.h"
#include "texcompress_s3tc.h"
#include "texstate.h"
#include "transformfeedback.h"
#include "mtypes.h"
#include "varray.h"
#include "version.h"
#include "viewport.h"
#include "vtxfmt.h"
#include "program/program.h"
#include "program/prog_print.h"
#include "math/m_matrix.h"
#include "main/dispatch.h" /* for _gloffset_COUNT */

#ifdef USE_SPARC_ASM
#include "sparc/sparc.h"
#endif

#include "glsl_parser_extras.h"
#include <stdbool.h>


#ifndef MESA_VERBOSE
int MESA_VERBOSE = 0;
#endif

#ifndef MESA_DEBUG_FLAGS
int MESA_DEBUG_FLAGS = 0;
#endif


/* ubyte -> float conversion */
GLfloat _mesa_ubyte_to_float_color_tab[256];



/**
 * Swap buffers notification callback.
 * 
 * \param ctx GL context.
 *
 * Called by window system just before swapping buffers.
 * We have to finish any pending rendering.
 */
void
_mesa_notifySwapBuffers(struct gl_context *ctx)
{
   if (MESA_VERBOSE & VERBOSE_SWAPBUFFERS)
      _mesa_debug(ctx, "SwapBuffers\n");
   FLUSH_CURRENT( ctx, 0 );
   if (ctx->Driver.Flush) {
      ctx->Driver.Flush(ctx);
   }
}


/**********************************************************************/
/** \name GL Visual allocation/destruction                            */
/**********************************************************************/
/*@{*/

/**
 * Allocates a struct gl_config structure and initializes it via
 * _mesa_initialize_visual().
 * 
 * \param dbFlag double buffering
 * \param stereoFlag stereo buffer
 * \param depthBits requested bits per depth buffer value. Any value in [0, 32]
 * is acceptable but the actual depth type will be GLushort or GLuint as
 * needed.
 * \param stencilBits requested minimum bits per stencil buffer value
 * \param accumRedBits, accumGreenBits, accumBlueBits, accumAlphaBits number
 * of bits per color component in accum buffer.
 * \param indexBits number of bits per pixel if \p rgbFlag is GL_FALSE
 * \param redBits number of bits per color component in frame buffer for RGB(A)
 * mode.  We always use 8 in core Mesa though.
 * \param greenBits same as above.
 * \param blueBits same as above.
 * \param alphaBits same as above.
 * \param numSamples not really used.
 * 
 * \return pointer to new struct gl_config or NULL if requested parameters
 * can't be met.
 *
 * \note Need to add params for level and numAuxBuffers (at least)
 */
struct gl_config *
_mesa_create_visual( GLboolean dbFlag,
                     GLboolean stereoFlag,
                     GLint redBits,
                     GLint greenBits,
                     GLint blueBits,
                     GLint alphaBits,
                     GLint depthBits,
                     GLint stencilBits,
                     GLint accumRedBits,
                     GLint accumGreenBits,
                     GLint accumBlueBits,
                     GLint accumAlphaBits,
                     GLint numSamples )
{
   struct gl_config *vis = CALLOC_STRUCT(gl_config);
   if (vis) {
      if (!_mesa_initialize_visual(vis, dbFlag, stereoFlag,
                                   redBits, greenBits, blueBits, alphaBits,
                                   depthBits, stencilBits,
                                   accumRedBits, accumGreenBits,
                                   accumBlueBits, accumAlphaBits,
                                   numSamples)) {
         free(vis);
         return NULL;
      }
   }
   return vis;
}


/**
 * Makes some sanity checks and fills in the fields of the struct
 * gl_config object with the given parameters.  If the caller needs to
 * set additional fields, he should just probably init the whole
 * gl_config object himself.
 *
 * \return GL_TRUE on success, or GL_FALSE on failure.
 *
 * \sa _mesa_create_visual() above for the parameter description.
 */
GLboolean
_mesa_initialize_visual( struct gl_config *vis,
                         GLboolean dbFlag,
                         GLboolean stereoFlag,
                         GLint redBits,
                         GLint greenBits,
                         GLint blueBits,
                         GLint alphaBits,
                         GLint depthBits,
                         GLint stencilBits,
                         GLint accumRedBits,
                         GLint accumGreenBits,
                         GLint accumBlueBits,
                         GLint accumAlphaBits,
                         GLint numSamples )
{
   assert(vis);

   if (depthBits < 0 || depthBits > 32) {
      return GL_FALSE;
   }
   if (stencilBits < 0 || stencilBits > 8) {
      return GL_FALSE;
   }
   assert(accumRedBits >= 0);
   assert(accumGreenBits >= 0);
   assert(accumBlueBits >= 0);
   assert(accumAlphaBits >= 0);

   vis->rgbMode          = GL_TRUE;
   vis->doubleBufferMode = dbFlag;
   vis->stereoMode       = stereoFlag;

   vis->redBits          = redBits;
   vis->greenBits        = greenBits;
   vis->blueBits         = blueBits;
   vis->alphaBits        = alphaBits;
   vis->rgbBits          = redBits + greenBits + blueBits;

   vis->indexBits      = 0;
   vis->depthBits      = depthBits;
   vis->stencilBits    = stencilBits;

   vis->accumRedBits   = accumRedBits;
   vis->accumGreenBits = accumGreenBits;
   vis->accumBlueBits  = accumBlueBits;
   vis->accumAlphaBits = accumAlphaBits;

   vis->haveAccumBuffer   = accumRedBits > 0;
   vis->haveDepthBuffer   = depthBits > 0;
   vis->haveStencilBuffer = stencilBits > 0;

   vis->numAuxBuffers = 0;
   vis->level = 0;
   vis->sampleBuffers = numSamples > 0 ? 1 : 0;
   vis->samples = numSamples;

   return GL_TRUE;
}


/**
 * Destroy a visual and free its memory.
 *
 * \param vis visual.
 * 
 * Frees the visual structure.
 */
void
_mesa_destroy_visual( struct gl_config *vis )
{
   free(vis);
}

/*@}*/


/**********************************************************************/
/** \name Context allocation, initialization, destroying
 *
 * The purpose of the most initialization functions here is to provide the
 * default state values according to the OpenGL specification.
 */
/**********************************************************************/
/*@{*/


/**
 * This is lame.  gdb only seems to recognize enum types that are
 * actually used somewhere.  We want to be able to print/use enum
 * values such as TEXTURE_2D_INDEX in gdb.  But we don't actually use
 * the gl_texture_index type anywhere.  Thus, this lame function.
 */
static void
dummy_enum_func(void)
{
   gl_buffer_index bi = BUFFER_FRONT_LEFT;
   gl_face_index fi = FACE_POS_X;
   gl_frag_result fr = FRAG_RESULT_DEPTH;
   gl_texture_index ti = TEXTURE_2D_ARRAY_INDEX;
   gl_vert_attrib va = VERT_ATTRIB_POS;
   gl_varying_slot vs = VARYING_SLOT_POS;

   (void) bi;
   (void) fi;
   (void) fr;
   (void) ti;
   (void) va;
   (void) vs;
}


/**
 * One-time initialization mutex lock.
 *
 * \sa Used by one_time_init().
 */
_glthread_DECLARE_STATIC_MUTEX(OneTimeLock);



/**
 * Calls all the various one-time-init functions in Mesa.
 *
 * While holding a global mutex lock, calls several initialization functions,
 * and sets the glapi callbacks if the \c MESA_DEBUG environment variable is
 * defined.
 *
 * \sa _math_init().
 */
static void
one_time_init( struct gl_context *ctx )
{
   static GLbitfield api_init_mask = 0x0;

   _glthread_LOCK_MUTEX(OneTimeLock);

   /* truly one-time init */
   if (!api_init_mask) {
      GLuint i;

      /* do some implementation tests */
      assert( sizeof(GLbyte) == 1 );
      assert( sizeof(GLubyte) == 1 );
      assert( sizeof(GLshort) == 2 );
      assert( sizeof(GLushort) == 2 );
      assert( sizeof(GLint) == 4 );
      assert( sizeof(GLuint) == 4 );

      _mesa_get_cpu_features();

      for (i = 0; i < 256; i++) {
         _mesa_ubyte_to_float_color_tab[i] = (float) i / 255.0F;
      }

#if defined(DEBUG) && defined(__DATE__) && defined(__TIME__)
      if (MESA_VERBOSE != 0) {
	 _mesa_debug(ctx, "Mesa %s DEBUG build %s %s\n",
		     PACKAGE_VERSION, __DATE__, __TIME__);
      }
#endif

#ifdef DEBUG
      _mesa_test_formats();
#endif
   }

   /* per-API one-time init */
   if (!(api_init_mask & (1 << ctx->API))) {
      _mesa_init_get_hash(ctx);

      _mesa_init_remap_table();
   }

   api_init_mask |= 1 << ctx->API;

   _glthread_UNLOCK_MUTEX(OneTimeLock);

   /* Hopefully atexit() is widely available.  If not, we may need some
    * #ifdef tests here.
    */
   atexit(_mesa_destroy_shader_compiler);

   dummy_enum_func();
}


/**
 * Initialize fields of gl_current_attrib (aka ctx->Current.*)
 */
static void
_mesa_init_current(struct gl_context *ctx)
{
   GLuint i;

   /* Init all to (0,0,0,1) */
   for (i = 0; i < Elements(ctx->Current.Attrib); i++) {
      ASSIGN_4V( ctx->Current.Attrib[i], 0.0, 0.0, 0.0, 1.0 );
   }

   /* redo special cases: */
   ASSIGN_4V( ctx->Current.Attrib[VERT_ATTRIB_WEIGHT], 1.0, 0.0, 0.0, 0.0 );
   ASSIGN_4V( ctx->Current.Attrib[VERT_ATTRIB_NORMAL], 0.0, 0.0, 1.0, 1.0 );
   ASSIGN_4V( ctx->Current.Attrib[VERT_ATTRIB_COLOR0], 1.0, 1.0, 1.0, 1.0 );
   ASSIGN_4V( ctx->Current.Attrib[VERT_ATTRIB_COLOR1], 0.0, 0.0, 0.0, 1.0 );
   ASSIGN_4V( ctx->Current.Attrib[VERT_ATTRIB_COLOR_INDEX], 1.0, 0.0, 0.0, 1.0 );
   ASSIGN_4V( ctx->Current.Attrib[VERT_ATTRIB_EDGEFLAG], 1.0, 0.0, 0.0, 1.0 );
}


/**
 * Init vertex/fragment/geometry program limits.
 * Important: drivers should override these with actual limits.
 */
static void
init_program_limits(struct gl_context *ctx, gl_shader_stage stage,
                    struct gl_program_constants *prog)
{
   prog->MaxInstructions = MAX_PROGRAM_INSTRUCTIONS;
   prog->MaxAluInstructions = MAX_PROGRAM_INSTRUCTIONS;
   prog->MaxTexInstructions = MAX_PROGRAM_INSTRUCTIONS;
   prog->MaxTexIndirections = MAX_PROGRAM_INSTRUCTIONS;
   prog->MaxTemps = MAX_PROGRAM_TEMPS;
   prog->MaxEnvParams = MAX_PROGRAM_ENV_PARAMS;
   prog->MaxLocalParams = MAX_PROGRAM_LOCAL_PARAMS;
   prog->MaxAddressOffset = MAX_PROGRAM_LOCAL_PARAMS;

   switch (stage) {
   case MESA_SHADER_VERTEX:
      prog->MaxParameters = MAX_VERTEX_PROGRAM_PARAMS;
      prog->MaxAttribs = MAX_VERTEX_GENERIC_ATTRIBS;
      prog->MaxAddressRegs = MAX_VERTEX_PROGRAM_ADDRESS_REGS;
      prog->MaxUniformComponents = 4 * MAX_UNIFORMS;
      prog->MaxInputComponents = 0; /* value not used */
      prog->MaxOutputComponents = 16 * 4; /* old limit not to break tnl and swrast */
      break;
   case MESA_SHADER_FRAGMENT:
      prog->MaxParameters = MAX_NV_FRAGMENT_PROGRAM_PARAMS;
      prog->MaxAttribs = MAX_NV_FRAGMENT_PROGRAM_INPUTS;
      prog->MaxAddressRegs = MAX_FRAGMENT_PROGRAM_ADDRESS_REGS;
      prog->MaxUniformComponents = 4 * MAX_UNIFORMS;
      prog->MaxInputComponents = 16 * 4; /* old limit not to break tnl and swrast */
      prog->MaxOutputComponents = 0; /* value not used */
      break;
   case MESA_SHADER_GEOMETRY:
      prog->MaxParameters = MAX_VERTEX_PROGRAM_PARAMS;
      prog->MaxAttribs = MAX_VERTEX_GENERIC_ATTRIBS;
      prog->MaxAddressRegs = MAX_VERTEX_PROGRAM_ADDRESS_REGS;
      prog->MaxUniformComponents = 4 * MAX_UNIFORMS;
      prog->MaxInputComponents = 16 * 4; /* old limit not to break tnl and swrast */
      prog->MaxOutputComponents = 16 * 4; /* old limit not to break tnl and swrast */
      break;
   case MESA_SHADER_COMPUTE:
      prog->MaxParameters = 0; /* not meaningful for compute shaders */
      prog->MaxAttribs = 0; /* not meaningful for compute shaders */
      prog->MaxAddressRegs = 0; /* not meaningful for compute shaders */
      prog->MaxUniformComponents = 4 * MAX_UNIFORMS;
      prog->MaxInputComponents = 0; /* not meaningful for compute shaders */
      prog->MaxOutputComponents = 0; /* not meaningful for compute shaders */
      break;
   default:
      assert(0 && "Bad shader stage in init_program_limits()");
   }

   /* Set the native limits to zero.  This implies that there is no native
    * support for shaders.  Let the drivers fill in the actual values.
    */
   prog->MaxNativeInstructions = 0;
   prog->MaxNativeAluInstructions = 0;
   prog->MaxNativeTexInstructions = 0;
   prog->MaxNativeTexIndirections = 0;
   prog->MaxNativeAttribs = 0;
   prog->MaxNativeTemps = 0;
   prog->MaxNativeAddressRegs = 0;
   prog->MaxNativeParameters = 0;

   /* Set GLSL datatype range/precision info assuming IEEE float values.
    * Drivers should override these defaults as needed.
    */
   prog->MediumFloat.RangeMin = 127;
   prog->MediumFloat.RangeMax = 127;
   prog->MediumFloat.Precision = 23;
   prog->LowFloat = prog->HighFloat = prog->MediumFloat;

   /* Assume ints are stored as floats for now, since this is the least-common
    * denominator.  The OpenGL ES spec implies (page 132) that the precision
    * of integer types should be 0.  Practically speaking, IEEE
    * single-precision floating point values can only store integers in the
    * range [-0x01000000, 0x01000000] without loss of precision.
    */
   prog->MediumInt.RangeMin = 24;
   prog->MediumInt.RangeMax = 24;
   prog->MediumInt.Precision = 0;
   prog->LowInt = prog->HighInt = prog->MediumInt;

   prog->MaxUniformBlocks = 12;
   prog->MaxCombinedUniformComponents = (prog->MaxUniformComponents +
                                         ctx->Const.MaxUniformBlockSize / 4 *
                                         prog->MaxUniformBlocks);

   prog->MaxAtomicBuffers = 0;
   prog->MaxAtomicCounters = 0;
}


/**
 * Initialize fields of gl_constants (aka ctx->Const.*).
 * Use defaults from config.h.  The device drivers will often override
 * some of these values (such as number of texture units).
 */
static void 
_mesa_init_constants(struct gl_context *ctx)
{
   int i;
   assert(ctx);

   /* Constants, may be overriden (usually only reduced) by device drivers */
   ctx->Const.MaxTextureMbytes = MAX_TEXTURE_MBYTES;
   ctx->Const.MaxTextureLevels = MAX_TEXTURE_LEVELS;
   ctx->Const.Max3DTextureLevels = MAX_3D_TEXTURE_LEVELS;
   ctx->Const.MaxCubeTextureLevels = MAX_CUBE_TEXTURE_LEVELS;
   ctx->Const.MaxTextureRectSize = MAX_TEXTURE_RECT_SIZE;
   ctx->Const.MaxArrayTextureLayers = MAX_ARRAY_TEXTURE_LAYERS;
   ctx->Const.MaxTextureCoordUnits = MAX_TEXTURE_COORD_UNITS;
   ctx->Const.Program[MESA_SHADER_FRAGMENT].MaxTextureImageUnits = MAX_TEXTURE_IMAGE_UNITS;
   ctx->Const.MaxTextureUnits = MIN2(ctx->Const.MaxTextureCoordUnits,
                                     ctx->Const.Program[MESA_SHADER_FRAGMENT].MaxTextureImageUnits);
   ctx->Const.MaxTextureMaxAnisotropy = MAX_TEXTURE_MAX_ANISOTROPY;
   ctx->Const.MaxTextureLodBias = MAX_TEXTURE_LOD_BIAS;
   ctx->Const.MaxTextureBufferSize = 65536;
   ctx->Const.TextureBufferOffsetAlignment = 1;
   ctx->Const.MaxArrayLockSize = MAX_ARRAY_LOCK_SIZE;
   ctx->Const.SubPixelBits = SUB_PIXEL_BITS;
   ctx->Const.MinPointSize = MIN_POINT_SIZE;
   ctx->Const.MaxPointSize = MAX_POINT_SIZE;
   ctx->Const.MinPointSizeAA = MIN_POINT_SIZE;
   ctx->Const.MaxPointSizeAA = MAX_POINT_SIZE;
   ctx->Const.PointSizeGranularity = (GLfloat) POINT_SIZE_GRANULARITY;
   ctx->Const.MinLineWidth = MIN_LINE_WIDTH;
   ctx->Const.MaxLineWidth = MAX_LINE_WIDTH;
   ctx->Const.MinLineWidthAA = MIN_LINE_WIDTH;
   ctx->Const.MaxLineWidthAA = MAX_LINE_WIDTH;
   ctx->Const.LineWidthGranularity = (GLfloat) LINE_WIDTH_GRANULARITY;
   ctx->Const.MaxClipPlanes = 6;
   ctx->Const.MaxLights = MAX_LIGHTS;
   ctx->Const.MaxShininess = 128.0;
   ctx->Const.MaxSpotExponent = 128.0;
   ctx->Const.MaxViewportWidth = MAX_VIEWPORT_WIDTH;
   ctx->Const.MaxViewportHeight = MAX_VIEWPORT_HEIGHT;
   ctx->Const.MinMapBufferAlignment = 64;

   /* Driver must override these values if ARB_viewport_array is supported. */
   ctx->Const.MaxViewports = 1;
   ctx->Const.ViewportSubpixelBits = 0;
   ctx->Const.ViewportBounds.Min = 0;
   ctx->Const.ViewportBounds.Max = 0;

   /* Driver must override if it supports ARB_viewport_array */
   ctx->Const.MaxViewports = 1;

   /** GL_ARB_uniform_buffer_object */
   ctx->Const.MaxCombinedUniformBlocks = 36;
   ctx->Const.MaxUniformBufferBindings = 36;
   ctx->Const.MaxUniformBlockSize = 16384;
   ctx->Const.UniformBufferOffsetAlignment = 1;

   for (i = 0; i < MESA_SHADER_STAGES; i++)
      init_program_limits(ctx, i, &ctx->Const.Program[i]);

   ctx->Const.MaxProgramMatrices = MAX_PROGRAM_MATRICES;
   ctx->Const.MaxProgramMatrixStackDepth = MAX_PROGRAM_MATRIX_STACK_DEPTH;

   /* CheckArrayBounds is overriden by drivers/x11 for X server */
   ctx->Const.CheckArrayBounds = GL_FALSE;

   /* GL_ARB_draw_buffers */
   ctx->Const.MaxDrawBuffers = MAX_DRAW_BUFFERS;

   ctx->Const.MaxColorAttachments = MAX_COLOR_ATTACHMENTS;
   ctx->Const.MaxRenderbufferSize = MAX_RENDERBUFFER_SIZE;

   ctx->Const.Program[MESA_SHADER_VERTEX].MaxTextureImageUnits = MAX_TEXTURE_IMAGE_UNITS;
   ctx->Const.MaxCombinedTextureImageUnits = MAX_COMBINED_TEXTURE_IMAGE_UNITS;
   ctx->Const.MaxVarying = 16; /* old limit not to break tnl and swrast */
   ctx->Const.Program[MESA_SHADER_GEOMETRY].MaxTextureImageUnits = MAX_TEXTURE_IMAGE_UNITS;
   ctx->Const.MaxGeometryOutputVertices = MAX_GEOMETRY_OUTPUT_VERTICES;
   ctx->Const.MaxGeometryTotalOutputComponents = MAX_GEOMETRY_TOTAL_OUTPUT_COMPONENTS;

   /* Shading language version */
   if (_mesa_is_desktop_gl(ctx)) {
      ctx->Const.GLSLVersion = 120;
      _mesa_override_glsl_version(ctx);
   }
   else if (ctx->API == API_OPENGLES2) {
      ctx->Const.GLSLVersion = 100;
   }
   else if (ctx->API == API_OPENGLES) {
      ctx->Const.GLSLVersion = 0; /* GLSL not supported */
   }

   /* GL_ARB_framebuffer_object */
   ctx->Const.MaxSamples = 0;

   /* GL_ARB_sync */
   ctx->Const.MaxServerWaitTimeout = 0x1fff7fffffffULL;

   /* GL_ATI_envmap_bumpmap */
   ctx->Const.SupportedBumpUnits = SUPPORTED_ATI_BUMP_UNITS;

   /* GL_EXT_provoking_vertex */
   ctx->Const.QuadsFollowProvokingVertexConvention = GL_TRUE;

   /* GL_EXT_transform_feedback */
   ctx->Const.MaxTransformFeedbackBuffers = MAX_FEEDBACK_BUFFERS;
   ctx->Const.MaxTransformFeedbackSeparateComponents = 4 * MAX_FEEDBACK_ATTRIBS;
   ctx->Const.MaxTransformFeedbackInterleavedComponents = 4 * MAX_FEEDBACK_ATTRIBS;
   ctx->Const.MaxVertexStreams = 1;

   /* GL 3.2  */
   ctx->Const.ProfileMask = ctx->API == API_OPENGL_CORE
                          ? GL_CONTEXT_CORE_PROFILE_BIT
                          : GL_CONTEXT_COMPATIBILITY_PROFILE_BIT;

   /** GL_EXT_gpu_shader4 */
   ctx->Const.MinProgramTexelOffset = -8;
   ctx->Const.MaxProgramTexelOffset = 7;

   /* GL_ARB_texture_gather */
   ctx->Const.MinProgramTextureGatherOffset = -8;
   ctx->Const.MaxProgramTextureGatherOffset = 7;

   /* GL_ARB_robustness */
   ctx->Const.ResetStrategy = GL_NO_RESET_NOTIFICATION_ARB;

   /* PrimitiveRestart */
   ctx->Const.PrimitiveRestartInSoftware = GL_FALSE;

   /* ES 3.0 or ARB_ES3_compatibility */
   ctx->Const.MaxElementIndex = 0xffffffffu;

   /* GL_ARB_texture_multisample */
   ctx->Const.MaxColorTextureSamples = 1;
   ctx->Const.MaxDepthTextureSamples = 1;
   ctx->Const.MaxIntegerSamples = 1;

   /* GL_ARB_shader_atomic_counters */
   ctx->Const.MaxAtomicBufferBindings = MAX_COMBINED_ATOMIC_BUFFERS;
   ctx->Const.MaxAtomicBufferSize = MAX_ATOMIC_COUNTERS * ATOMIC_COUNTER_SIZE;
   ctx->Const.MaxCombinedAtomicBuffers = MAX_COMBINED_ATOMIC_BUFFERS;
   ctx->Const.MaxCombinedAtomicCounters = MAX_ATOMIC_COUNTERS;

   /* GL_ARB_vertex_attrib_binding */
   ctx->Const.MaxVertexAttribRelativeOffset = 2047;
   ctx->Const.MaxVertexAttribBindings = MAX_VERTEX_GENERIC_ATTRIBS;

   /* GL_ARB_compute_shader */
   ctx->Const.MaxComputeWorkGroupCount[0] = 65535;
   ctx->Const.MaxComputeWorkGroupCount[1] = 65535;
   ctx->Const.MaxComputeWorkGroupCount[2] = 65535;
   ctx->Const.MaxComputeWorkGroupSize[0] = 1024;
   ctx->Const.MaxComputeWorkGroupSize[1] = 1024;
   ctx->Const.MaxComputeWorkGroupSize[2] = 64;
   ctx->Const.MaxComputeWorkGroupInvocations = 1024;

   /** GL_ARB_gpu_shader5 */
   ctx->Const.MinFragmentInterpolationOffset = MIN_FRAGMENT_INTERPOLATION_OFFSET;
   ctx->Const.MaxFragmentInterpolationOffset = MAX_FRAGMENT_INTERPOLATION_OFFSET;
}


/**
 * Do some sanity checks on the limits/constants for the given context.
 * Only called the first time a context is bound.
 */
static void
check_context_limits(struct gl_context *ctx)
{
   /* check that we don't exceed the size of various bitfields */
   assert(VARYING_SLOT_MAX <=
	  (8 * sizeof(ctx->VertexProgram._Current->Base.OutputsWritten)));
   assert(VARYING_SLOT_MAX <=
	  (8 * sizeof(ctx->FragmentProgram._Current->Base.InputsRead)));

   /* shader-related checks */
   assert(ctx->Const.Program[MESA_SHADER_FRAGMENT].MaxLocalParams <= MAX_PROGRAM_LOCAL_PARAMS);
   assert(ctx->Const.Program[MESA_SHADER_VERTEX].MaxLocalParams <= MAX_PROGRAM_LOCAL_PARAMS);

   /* Texture unit checks */
   assert(ctx->Const.Program[MESA_SHADER_FRAGMENT].MaxTextureImageUnits > 0);
   assert(ctx->Const.Program[MESA_SHADER_FRAGMENT].MaxTextureImageUnits <= MAX_TEXTURE_IMAGE_UNITS);
   assert(ctx->Const.MaxTextureCoordUnits > 0);
   assert(ctx->Const.MaxTextureCoordUnits <= MAX_TEXTURE_COORD_UNITS);
   assert(ctx->Const.MaxTextureUnits > 0);
   assert(ctx->Const.MaxTextureUnits <= MAX_TEXTURE_IMAGE_UNITS);
   assert(ctx->Const.MaxTextureUnits <= MAX_TEXTURE_COORD_UNITS);
   assert(ctx->Const.MaxTextureUnits == MIN2(ctx->Const.Program[MESA_SHADER_FRAGMENT].MaxTextureImageUnits,
                                             ctx->Const.MaxTextureCoordUnits));
   assert(ctx->Const.MaxCombinedTextureImageUnits > 0);
   assert(ctx->Const.MaxCombinedTextureImageUnits <= MAX_COMBINED_TEXTURE_IMAGE_UNITS);
   assert(ctx->Const.MaxTextureCoordUnits <= MAX_COMBINED_TEXTURE_IMAGE_UNITS);
   /* number of coord units cannot be greater than number of image units */
   assert(ctx->Const.MaxTextureCoordUnits <= ctx->Const.Program[MESA_SHADER_FRAGMENT].MaxTextureImageUnits);


   /* Texture size checks */
   assert(ctx->Const.MaxTextureLevels <= MAX_TEXTURE_LEVELS);
   assert(ctx->Const.Max3DTextureLevels <= MAX_3D_TEXTURE_LEVELS);
   assert(ctx->Const.MaxCubeTextureLevels <= MAX_CUBE_TEXTURE_LEVELS);
   assert(ctx->Const.MaxTextureRectSize <= MAX_TEXTURE_RECT_SIZE);

   /* Texture level checks */
   assert(MAX_TEXTURE_LEVELS >= MAX_3D_TEXTURE_LEVELS);
   assert(MAX_TEXTURE_LEVELS >= MAX_CUBE_TEXTURE_LEVELS);

   /* Max texture size should be <= max viewport size (render to texture) */
   assert((1U << (ctx->Const.MaxTextureLevels - 1))
          <= ctx->Const.MaxViewportWidth);
   assert((1U << (ctx->Const.MaxTextureLevels - 1))
          <= ctx->Const.MaxViewportHeight);

   assert(ctx->Const.MaxDrawBuffers <= MAX_DRAW_BUFFERS);

   /* if this fails, add more enum values to gl_buffer_index */
   assert(BUFFER_COLOR0 + MAX_DRAW_BUFFERS <= BUFFER_COUNT);

   /* XXX probably add more tests */
}


/**
 * Initialize the attribute groups in a GL context.
 *
 * \param ctx GL context.
 *
 * Initializes all the attributes, calling the respective <tt>init*</tt>
 * functions for the more complex data structures.
 */
static GLboolean
init_attrib_groups(struct gl_context *ctx)
{
   assert(ctx);

   /* Constants */
   _mesa_init_constants( ctx );

   /* Extensions */
   _mesa_init_extensions( ctx );

   /* Attribute Groups */
   _mesa_init_accum( ctx );
   _mesa_init_attrib( ctx );
   _mesa_init_buffer_objects( ctx );
   _mesa_init_color( ctx );
   _mesa_init_current( ctx );
   _mesa_init_depth( ctx );
   _mesa_init_debug( ctx );
   _mesa_init_display_list( ctx );
   _mesa_init_errors( ctx );
   _mesa_init_eval( ctx );
   _mesa_init_fbobjects( ctx );
   _mesa_init_feedback( ctx );
   _mesa_init_fog( ctx );
   _mesa_init_hint( ctx );
   _mesa_init_line( ctx );
   _mesa_init_lighting( ctx );
   _mesa_init_matrix( ctx );
   _mesa_init_multisample( ctx );
   _mesa_init_performance_monitors( ctx );
   _mesa_init_pixel( ctx );
   _mesa_init_pixelstore( ctx );
   _mesa_init_point( ctx );
   _mesa_init_polygon( ctx );
   _mesa_init_program( ctx );
   _mesa_init_queryobj( ctx );
   _mesa_init_sync( ctx );
   _mesa_init_rastpos( ctx );
   _mesa_init_scissor( ctx );
   _mesa_init_shader_state( ctx );
   _mesa_init_stencil( ctx );
   _mesa_init_transform( ctx );
   _mesa_init_transform_feedback( ctx );
   _mesa_init_varray( ctx );
   _mesa_init_viewport( ctx );

   if (!_mesa_init_texture( ctx ))
      return GL_FALSE;

   _mesa_init_texture_s3tc( ctx );

   /* Miscellaneous */
   ctx->NewState = _NEW_ALL;
   ctx->NewDriverState = ~0;
   ctx->ErrorValue = GL_NO_ERROR;
   ctx->ShareGroupReset = false;
   ctx->varying_vp_inputs = VERT_BIT_ALL;

   return GL_TRUE;
}


/**
 * Update default objects in a GL context with respect to shared state.
 *
 * \param ctx GL context.
 *
 * Removes references to old default objects, (texture objects, program
 * objects, etc.) and changes to reference those from the current shared
 * state.
 */
static GLboolean
update_default_objects(struct gl_context *ctx)
{
   assert(ctx);

   _mesa_update_default_objects_program(ctx);
   _mesa_update_default_objects_texture(ctx);
   _mesa_update_default_objects_buffer_objects(ctx);

   return GL_TRUE;
}


/**
 * This is the default function we plug into all dispatch table slots
 * This helps prevents a segfault when someone calls a GL function without
 * first checking if the extension's supported.
 */
int
_mesa_generic_nop(void)
{
   GET_CURRENT_CONTEXT(ctx);
   _mesa_error(ctx, GL_INVALID_OPERATION,
               "unsupported function called "
               "(unsupported extension or deprecated function?)");
   return 0;
}


/**
 * Allocate and initialize a new dispatch table.
 */
struct _glapi_table *
_mesa_alloc_dispatch_table()
{
   /* Find the larger of Mesa's dispatch table and libGL's dispatch table.
    * In practice, this'll be the same for stand-alone Mesa.  But for DRI
    * Mesa we do this to accomodate different versions of libGL and various
    * DRI drivers.
    */
   GLint numEntries = MAX2(_glapi_get_dispatch_table_size(), _gloffset_COUNT);
   struct _glapi_table *table;

   table = malloc(numEntries * sizeof(_glapi_proc));
   if (table) {
      _glapi_proc *entry = (_glapi_proc *) table;
      GLint i;
      for (i = 0; i < numEntries; i++) {
         entry[i] = (_glapi_proc) _mesa_generic_nop;
      }
   }
   return table;
}

/**
 * Creates a minimal dispatch table for use within glBegin()/glEnd().
 *
 * This ensures that we generate GL_INVALID_OPERATION errors from most
 * functions, since the set of functions that are valid within Begin/End is
 * very small.
 *
 * From the GL 1.0 specification section 2.6.3, "GL Commands within
 * Begin/End"
 *
 *     "The only GL commands that are allowed within any Begin/End pairs are
 *      the commands for specifying vertex coordinates, vertex color, normal
 *      coordinates, and texture coordinates (Vertex, Color, Index, Normal,
 *      TexCoord), EvalCoord and EvalPoint commands (see section 5.1),
 *      commands for specifying lighting material parameters (Material
 *      commands see section 2.12.2), display list invocation commands
 *      (CallList and CallLists see section 5.4), and the EdgeFlag
 *      command. Executing Begin after Begin has already been executed but
 *      before an End is issued generates the INVALID OPERATION error, as does
 *      executing End without a previous corresponding Begin. Executing any
 *      other GL command within Begin/End results in the error INVALID
 *      OPERATION."
 *
 * The table entries for specifying vertex attributes are set up by
 * install_vtxfmt() and _mesa_loopback_init_api_table(), and End() and dlists
 * are set by install_vtxfmt() as well.
 */
static struct _glapi_table *
create_beginend_table(const struct gl_context *ctx)
{
   struct _glapi_table *table;

   table = _mesa_alloc_dispatch_table();
   if (!table)
      return NULL;

   /* Fill in functions which return a value, since they should return some
    * specific value even if they emit a GL_INVALID_OPERATION error from them
    * being called within glBegin()/glEnd().
    */
#define COPY_DISPATCH(func) SET_##func(table, GET_##func(ctx->Exec))

   COPY_DISPATCH(GenLists);
   COPY_DISPATCH(IsProgram);
   COPY_DISPATCH(IsVertexArray);
   COPY_DISPATCH(IsBuffer);
   COPY_DISPATCH(IsEnabled);
   COPY_DISPATCH(IsEnabledi);
   COPY_DISPATCH(IsRenderbuffer);
   COPY_DISPATCH(IsFramebuffer);
   COPY_DISPATCH(CheckFramebufferStatus);
   COPY_DISPATCH(RenderMode);
   COPY_DISPATCH(GetString);
   COPY_DISPATCH(GetStringi);
   COPY_DISPATCH(GetPointerv);
   COPY_DISPATCH(IsQuery);
   COPY_DISPATCH(IsSampler);
   COPY_DISPATCH(IsSync);
   COPY_DISPATCH(IsTexture);
   COPY_DISPATCH(IsTransformFeedback);
   COPY_DISPATCH(DeleteQueries);
   COPY_DISPATCH(AreTexturesResident);
   COPY_DISPATCH(FenceSync);
   COPY_DISPATCH(ClientWaitSync);
   COPY_DISPATCH(MapBuffer);
   COPY_DISPATCH(UnmapBuffer);
   COPY_DISPATCH(MapBufferRange);
   COPY_DISPATCH(ObjectPurgeableAPPLE);
   COPY_DISPATCH(ObjectUnpurgeableAPPLE);

   _mesa_loopback_init_api_table(ctx, table);

   return table;
}

void
_mesa_initialize_dispatch_tables(struct gl_context *ctx)
{
   /* Do the code-generated setup of the exec table in api_exec.c. */
   _mesa_initialize_exec_table(ctx);

   if (ctx->Save)
      _mesa_initialize_save_table(ctx);
}

/**
 * Initialize a struct gl_context struct (rendering context).
 *
 * This includes allocating all the other structs and arrays which hang off of
 * the context by pointers.
 * Note that the driver needs to pass in its dd_function_table here since
 * we need to at least call driverFunctions->NewTextureObject to create the
 * default texture objects.
 * 
 * Called by _mesa_create_context().
 *
 * Performs the imports and exports callback tables initialization, and
 * miscellaneous one-time initializations. If no shared context is supplied one
 * is allocated, and increase its reference count.  Setups the GL API dispatch
 * tables.  Initialize the TNL module. Sets the maximum Z buffer depth.
 * Finally queries the \c MESA_DEBUG and \c MESA_VERBOSE environment variables
 * for debug flags.
 *
 * \param ctx the context to initialize
 * \param api the GL API type to create the context for
 * \param visual describes the visual attributes for this context
 * \param share_list points to context to share textures, display lists,
 *        etc with, or NULL
 * \param driverFunctions table of device driver functions for this context
 *        to use
 */
GLboolean
_mesa_initialize_context(struct gl_context *ctx,
                         gl_api api,
                         const struct gl_config *visual,
                         struct gl_context *share_list,
                         const struct dd_function_table *driverFunctions)
{
   struct gl_shared_state *shared;
   int i;

   assert(driverFunctions->NewTextureObject);
   assert(driverFunctions->FreeTextureImageBuffer);

   ctx->API = api;
   ctx->Visual = *visual;
   ctx->DrawBuffer = NULL;
   ctx->ReadBuffer = NULL;
   ctx->WinSysDrawBuffer = NULL;
   ctx->WinSysReadBuffer = NULL;

   if (_mesa_is_desktop_gl(ctx)) {
      _mesa_override_gl_version(ctx);
   }

   /* misc one-time initializations */
   one_time_init(ctx);

   /* Plug in driver functions and context pointer here.
    * This is important because when we call alloc_shared_state() below
    * we'll call ctx->Driver.NewTextureObject() to create the default
    * textures.
    */
   ctx->Driver = *driverFunctions;

   if (share_list) {
      /* share state with another context */
      shared = share_list->Shared;
   }
   else {
      /* allocate new, unshared state */
      shared = _mesa_alloc_shared_state(ctx);
      if (!shared)
         return GL_FALSE;
   }

   _mesa_reference_shared_state(ctx, &ctx->Shared, shared);

   if (!init_attrib_groups( ctx ))
      goto fail;

   /* setup the API dispatch tables with all nop functions */
   ctx->OutsideBeginEnd = _mesa_alloc_dispatch_table();
   if (!ctx->OutsideBeginEnd)
      goto fail;
   ctx->Exec = ctx->OutsideBeginEnd;
   ctx->CurrentDispatch = ctx->OutsideBeginEnd;

   ctx->FragmentProgram._MaintainTexEnvProgram
      = (_mesa_getenv("MESA_TEX_PROG") != NULL);

   ctx->VertexProgram._MaintainTnlProgram
      = (_mesa_getenv("MESA_TNL_PROG") != NULL);
   if (ctx->VertexProgram._MaintainTnlProgram) {
      /* this is required... */
      ctx->FragmentProgram._MaintainTexEnvProgram = GL_TRUE;
   }

   /* Mesa core handles all the formats that mesa core knows about.
    * Drivers will want to override this list with just the formats
    * they can handle, and confirm that appropriate fallbacks exist in
    * _mesa_choose_tex_format().
    */
   memset(&ctx->TextureFormatSupported, GL_TRUE,
	  sizeof(ctx->TextureFormatSupported));

   switch (ctx->API) {
   case API_OPENGL_COMPAT:
      ctx->BeginEnd = create_beginend_table(ctx);
      ctx->Save = _mesa_alloc_dispatch_table();
      if (!ctx->BeginEnd || !ctx->Save)
         goto fail;

      /* fall-through */
   case API_OPENGL_CORE:
      break;
   case API_OPENGLES:
      /**
       * GL_OES_texture_cube_map says
       * "Initially all texture generation modes are set to REFLECTION_MAP_OES"
       */
      for (i = 0; i < MAX_TEXTURE_UNITS; i++) {
	 struct gl_texture_unit *texUnit = &ctx->Texture.Unit[i];
	 texUnit->GenS.Mode = GL_REFLECTION_MAP_NV;
	 texUnit->GenT.Mode = GL_REFLECTION_MAP_NV;
	 texUnit->GenR.Mode = GL_REFLECTION_MAP_NV;
	 texUnit->GenS._ModeBit = TEXGEN_REFLECTION_MAP_NV;
	 texUnit->GenT._ModeBit = TEXGEN_REFLECTION_MAP_NV;
	 texUnit->GenR._ModeBit = TEXGEN_REFLECTION_MAP_NV;
      }
      break;
   case API_OPENGLES2:
      ctx->FragmentProgram._MaintainTexEnvProgram = GL_TRUE;
      ctx->VertexProgram._MaintainTnlProgram = GL_TRUE;
      break;
   }

   ctx->FirstTimeCurrent = GL_TRUE;

   return GL_TRUE;

fail:
   _mesa_reference_shared_state(ctx, &ctx->Shared, NULL);
   free(ctx->BeginEnd);
   free(ctx->Exec);
   free(ctx->Save);
   return GL_FALSE;
}


/**
 * Allocate and initialize a struct gl_context structure.
 * Note that the driver needs to pass in its dd_function_table here since
 * we need to at least call driverFunctions->NewTextureObject to initialize
 * the rendering context.
 *
 * \param api the GL API type to create the context for
 * \param visual a struct gl_config pointer (we copy the struct contents)
 * \param share_list another context to share display lists with or NULL
 * \param driverFunctions points to the dd_function_table into which the
 *        driver has plugged in all its special functions.
 * 
 * \return pointer to a new __struct gl_contextRec or NULL if error.
 */
struct gl_context *
_mesa_create_context(gl_api api,
                     const struct gl_config *visual,
                     struct gl_context *share_list,
                     const struct dd_function_table *driverFunctions)
{
   struct gl_context *ctx;

   ASSERT(visual);

   ctx = calloc(1, sizeof(struct gl_context));
   if (!ctx)
      return NULL;

   if (_mesa_initialize_context(ctx, api, visual, share_list,
                                driverFunctions)) {
      return ctx;
   }
   else {
      free(ctx);
      return NULL;
   }
}


/**
 * Free the data associated with the given context.
 * 
 * But doesn't free the struct gl_context struct itself.
 *
 * \sa _mesa_initialize_context() and init_attrib_groups().
 */
void
_mesa_free_context_data( struct gl_context *ctx )
{
   if (!_mesa_get_current_context()){
      /* No current context, but we may need one in order to delete
       * texture objs, etc.  So temporarily bind the context now.
       */
      _mesa_make_current(ctx, NULL, NULL);
   }

   /* unreference WinSysDraw/Read buffers */
   _mesa_reference_framebuffer(&ctx->WinSysDrawBuffer, NULL);
   _mesa_reference_framebuffer(&ctx->WinSysReadBuffer, NULL);
   _mesa_reference_framebuffer(&ctx->DrawBuffer, NULL);
   _mesa_reference_framebuffer(&ctx->ReadBuffer, NULL);

   _mesa_reference_vertprog(ctx, &ctx->VertexProgram.Current, NULL);
   _mesa_reference_vertprog(ctx, &ctx->VertexProgram._Current, NULL);
   _mesa_reference_vertprog(ctx, &ctx->VertexProgram._TnlProgram, NULL);

   _mesa_reference_fragprog(ctx, &ctx->FragmentProgram.Current, NULL);
   _mesa_reference_fragprog(ctx, &ctx->FragmentProgram._Current, NULL);
   _mesa_reference_fragprog(ctx, &ctx->FragmentProgram._TexEnvProgram, NULL);

   _mesa_reference_vao(ctx, &ctx->Array.VAO, NULL);
   _mesa_reference_vao(ctx, &ctx->Array.DefaultVAO, NULL);

   _mesa_free_attrib_data(ctx);
   _mesa_free_buffer_objects(ctx);
   _mesa_free_lighting_data( ctx );
   _mesa_free_eval_data( ctx );
   _mesa_free_texture_data( ctx );
   _mesa_free_matrix_data( ctx );
   _mesa_free_viewport_data( ctx );
   _mesa_free_program_data(ctx);
   _mesa_free_shader_state(ctx);
   _mesa_free_queryobj_data(ctx);
   _mesa_free_sync_data(ctx);
   _mesa_free_varray_data(ctx);
   _mesa_free_transform_feedback(ctx);
   _mesa_free_performance_monitors(ctx);

   _mesa_reference_buffer_object(ctx, &ctx->Pack.BufferObj, NULL);
   _mesa_reference_buffer_object(ctx, &ctx->Unpack.BufferObj, NULL);
   _mesa_reference_buffer_object(ctx, &ctx->DefaultPacking.BufferObj, NULL);
   _mesa_reference_buffer_object(ctx, &ctx->Array.ArrayBufferObj, NULL);

   /* free dispatch tables */
   free(ctx->BeginEnd);
   free(ctx->Exec);
   free(ctx->Save);

   /* Shared context state (display lists, textures, etc) */
   _mesa_reference_shared_state(ctx, &ctx->Shared, NULL);

   /* needs to be after freeing shared state */
   _mesa_free_display_list_data(ctx);

   _mesa_free_errors_data(ctx);

   free((void *)ctx->Extensions.String);

   free(ctx->VersionString);

   /* unbind the context if it's currently bound */
   if (ctx == _mesa_get_current_context()) {
      _mesa_make_current(NULL, NULL, NULL);
   }
}


/**
 * Destroy a struct gl_context structure.
 *
 * \param ctx GL context.
 * 
 * Calls _mesa_free_context_data() and frees the gl_context object itself.
 */
void
_mesa_destroy_context( struct gl_context *ctx )
{
   if (ctx) {
      _mesa_free_context_data(ctx);
      free( (void *) ctx );
   }
}


/**
 * Copy attribute groups from one context to another.
 * 
 * \param src source context
 * \param dst destination context
 * \param mask bitwise OR of GL_*_BIT flags
 *
 * According to the bits specified in \p mask, copies the corresponding
 * attributes from \p src into \p dst.  For many of the attributes a simple \c
 * memcpy is not enough due to the existence of internal pointers in their data
 * structures.
 */
void
_mesa_copy_context( const struct gl_context *src, struct gl_context *dst,
                    GLuint mask )
{
   if (mask & GL_ACCUM_BUFFER_BIT) {
      /* OK to memcpy */
      dst->Accum = src->Accum;
   }
   if (mask & GL_COLOR_BUFFER_BIT) {
      /* OK to memcpy */
      dst->Color = src->Color;
   }
   if (mask & GL_CURRENT_BIT) {
      /* OK to memcpy */
      dst->Current = src->Current;
   }
   if (mask & GL_DEPTH_BUFFER_BIT) {
      /* OK to memcpy */
      dst->Depth = src->Depth;
   }
   if (mask & GL_ENABLE_BIT) {
      /* no op */
   }
   if (mask & GL_EVAL_BIT) {
      /* OK to memcpy */
      dst->Eval = src->Eval;
   }
   if (mask & GL_FOG_BIT) {
      /* OK to memcpy */
      dst->Fog = src->Fog;
   }
   if (mask & GL_HINT_BIT) {
      /* OK to memcpy */
      dst->Hint = src->Hint;
   }
   if (mask & GL_LIGHTING_BIT) {
      GLuint i;
      /* begin with memcpy */
      dst->Light = src->Light;
      /* fixup linked lists to prevent pointer insanity */
      make_empty_list( &(dst->Light.EnabledList) );
      for (i = 0; i < MAX_LIGHTS; i++) {
         if (dst->Light.Light[i].Enabled) {
            insert_at_tail(&(dst->Light.EnabledList), &(dst->Light.Light[i]));
         }
      }
   }
   if (mask & GL_LINE_BIT) {
      /* OK to memcpy */
      dst->Line = src->Line;
   }
   if (mask & GL_LIST_BIT) {
      /* OK to memcpy */
      dst->List = src->List;
   }
   if (mask & GL_PIXEL_MODE_BIT) {
      /* OK to memcpy */
      dst->Pixel = src->Pixel;
   }
   if (mask & GL_POINT_BIT) {
      /* OK to memcpy */
      dst->Point = src->Point;
   }
   if (mask & GL_POLYGON_BIT) {
      /* OK to memcpy */
      dst->Polygon = src->Polygon;
   }
   if (mask & GL_POLYGON_STIPPLE_BIT) {
      /* Use loop instead of memcpy due to problem with Portland Group's
       * C compiler.  Reported by John Stone.
       */
      GLuint i;
      for (i = 0; i < 32; i++) {
         dst->PolygonStipple[i] = src->PolygonStipple[i];
      }
   }
   if (mask & GL_SCISSOR_BIT) {
      /* OK to memcpy */
      dst->Scissor = src->Scissor;
   }
   if (mask & GL_STENCIL_BUFFER_BIT) {
      /* OK to memcpy */
      dst->Stencil = src->Stencil;
   }
   if (mask & GL_TEXTURE_BIT) {
      /* Cannot memcpy because of pointers */
      _mesa_copy_texture_state(src, dst);
   }
   if (mask & GL_TRANSFORM_BIT) {
      /* OK to memcpy */
      dst->Transform = src->Transform;
   }
   if (mask & GL_VIEWPORT_BIT) {
      /* Cannot use memcpy, because of pointers in GLmatrix _WindowMap */
      unsigned i;
      for (i = 0; i < src->Const.MaxViewports; i++) {
         dst->ViewportArray[i].X = src->ViewportArray[i].X;
         dst->ViewportArray[i].Y = src->ViewportArray[i].Y;
         dst->ViewportArray[i].Width = src->ViewportArray[i].Width;
         dst->ViewportArray[i].Height = src->ViewportArray[i].Height;
         dst->ViewportArray[i].Near = src->ViewportArray[i].Near;
         dst->ViewportArray[i].Far = src->ViewportArray[i].Far;
         _math_matrix_copy(&dst->ViewportArray[i]._WindowMap,
                           &src->ViewportArray[i]._WindowMap);
      }
   }

   /* XXX FIXME:  Call callbacks?
    */
   dst->NewState = _NEW_ALL;
   dst->NewDriverState = ~0;
}


/**
 * Check if the given context can render into the given framebuffer
 * by checking visual attributes.
 *
 * Most of these tests could go away because Mesa is now pretty flexible
 * in terms of mixing rendering contexts with framebuffers.  As long
 * as RGB vs. CI mode agree, we're probably good.
 *
 * \return GL_TRUE if compatible, GL_FALSE otherwise.
 */
static GLboolean 
check_compatible(const struct gl_context *ctx,
                 const struct gl_framebuffer *buffer)
{
   const struct gl_config *ctxvis = &ctx->Visual;
   const struct gl_config *bufvis = &buffer->Visual;

   if (buffer == _mesa_get_incomplete_framebuffer())
      return GL_TRUE;

#if 0
   /* disabling this fixes the fgl_glxgears pbuffer demo */
   if (ctxvis->doubleBufferMode && !bufvis->doubleBufferMode)
      return GL_FALSE;
#endif
   if (ctxvis->stereoMode && !bufvis->stereoMode)
      return GL_FALSE;
   if (ctxvis->haveAccumBuffer && !bufvis->haveAccumBuffer)
      return GL_FALSE;
   if (ctxvis->haveDepthBuffer && !bufvis->haveDepthBuffer)
      return GL_FALSE;
   if (ctxvis->haveStencilBuffer && !bufvis->haveStencilBuffer)
      return GL_FALSE;
   if (ctxvis->redMask && ctxvis->redMask != bufvis->redMask)
      return GL_FALSE;
   if (ctxvis->greenMask && ctxvis->greenMask != bufvis->greenMask)
      return GL_FALSE;
   if (ctxvis->blueMask && ctxvis->blueMask != bufvis->blueMask)
      return GL_FALSE;
#if 0
   /* disabled (see bug 11161) */
   if (ctxvis->depthBits && ctxvis->depthBits != bufvis->depthBits)
      return GL_FALSE;
#endif
   if (ctxvis->stencilBits && ctxvis->stencilBits != bufvis->stencilBits)
      return GL_FALSE;

   return GL_TRUE;
}


/**
 * Check if the viewport/scissor size has not yet been initialized.
 * Initialize the size if the given width and height are non-zero.
 */
void
_mesa_check_init_viewport(struct gl_context *ctx, GLuint width, GLuint height)
{
   if (!ctx->ViewportInitialized && width > 0 && height > 0) {
      unsigned i;

      /* Note: set flag here, before calling _mesa_set_viewport(), to prevent
       * potential infinite recursion.
       */
      ctx->ViewportInitialized = GL_TRUE;

      /* Note: ctx->Const.MaxViewports may not have been set by the driver
       * yet, so just initialize all of them.
       */
      for (i = 0; i < MAX_VIEWPORTS; i++) {
         _mesa_set_viewport(ctx, i, 0, 0, width, height);
         _mesa_set_scissor(ctx, i, 0, 0, width, height);
      }
   }
}


/**
 * Bind the given context to the given drawBuffer and readBuffer and
 * make it the current context for the calling thread.
 * We'll render into the drawBuffer and read pixels from the
 * readBuffer (i.e. glRead/CopyPixels, glCopyTexImage, etc).
 *
 * We check that the context's and framebuffer's visuals are compatible
 * and return immediately if they're not.
 *
 * \param newCtx  the new GL context. If NULL then there will be no current GL
 *                context.
 * \param drawBuffer  the drawing framebuffer
 * \param readBuffer  the reading framebuffer
 */
GLboolean
_mesa_make_current( struct gl_context *newCtx,
                    struct gl_framebuffer *drawBuffer,
                    struct gl_framebuffer *readBuffer )
{
   GET_CURRENT_CONTEXT(curCtx);

   if (MESA_VERBOSE & VERBOSE_API)
      _mesa_debug(newCtx, "_mesa_make_current()\n");

   /* Check that the context's and framebuffer's visuals are compatible.
    */
   if (newCtx && drawBuffer && newCtx->WinSysDrawBuffer != drawBuffer) {
      if (!check_compatible(newCtx, drawBuffer)) {
         _mesa_warning(newCtx,
              "MakeCurrent: incompatible visuals for context and drawbuffer");
         return GL_FALSE;
      }
   }
   if (newCtx && readBuffer && newCtx->WinSysReadBuffer != readBuffer) {
      if (!check_compatible(newCtx, readBuffer)) {
         _mesa_warning(newCtx,
              "MakeCurrent: incompatible visuals for context and readbuffer");
         return GL_FALSE;
      }
   }

   if (curCtx && 
      (curCtx->WinSysDrawBuffer || curCtx->WinSysReadBuffer) &&
       /* make sure this context is valid for flushing */
      curCtx != newCtx)
      _mesa_flush(curCtx);

   /* We used to call _glapi_check_multithread() here.  Now do it in drivers */
   _glapi_set_context((void *) newCtx);
   ASSERT(_mesa_get_current_context() == newCtx);

   if (!newCtx) {
      _glapi_set_dispatch(NULL);  /* none current */
   }
   else {
      _glapi_set_dispatch(newCtx->CurrentDispatch);

      if (drawBuffer && readBuffer) {
         ASSERT(_mesa_is_winsys_fbo(drawBuffer));
         ASSERT(_mesa_is_winsys_fbo(readBuffer));
         _mesa_reference_framebuffer(&newCtx->WinSysDrawBuffer, drawBuffer);
         _mesa_reference_framebuffer(&newCtx->WinSysReadBuffer, readBuffer);

         /*
          * Only set the context's Draw/ReadBuffer fields if they're NULL
          * or not bound to a user-created FBO.
          */
         if (!newCtx->DrawBuffer || _mesa_is_winsys_fbo(newCtx->DrawBuffer)) {
            _mesa_reference_framebuffer(&newCtx->DrawBuffer, drawBuffer);
            /* Update the FBO's list of drawbuffers/renderbuffers.
             * For winsys FBOs this comes from the GL state (which may have
             * changed since the last time this FBO was bound).
             */
            _mesa_update_draw_buffers(newCtx);
         }
         if (!newCtx->ReadBuffer || _mesa_is_winsys_fbo(newCtx->ReadBuffer)) {
            _mesa_reference_framebuffer(&newCtx->ReadBuffer, readBuffer);
         }

         /* XXX only set this flag if we're really changing the draw/read
          * framebuffer bindings.
          */
	 newCtx->NewState |= _NEW_BUFFERS;

         if (drawBuffer) {
            _mesa_check_init_viewport(newCtx,
                                      drawBuffer->Width, drawBuffer->Height);
         }
      }

      if (newCtx->FirstTimeCurrent) {
         assert(newCtx->Version > 0);

         newCtx->Extensions.String = _mesa_make_extension_string(newCtx);

         check_context_limits(newCtx);

         /* We can use this to help debug user's problems.  Tell them to set
          * the MESA_INFO env variable before running their app.  Then the
          * first time each context is made current we'll print some useful
          * information.
          */
	 if (_mesa_getenv("MESA_INFO")) {
	    _mesa_print_info(newCtx);
	 }

	 newCtx->FirstTimeCurrent = GL_FALSE;
      }
   }
   
   return GL_TRUE;
}


/**
 * Make context 'ctx' share the display lists, textures and programs
 * that are associated with 'ctxToShare'.
 * Any display lists, textures or programs associated with 'ctx' will
 * be deleted if nobody else is sharing them.
 */
GLboolean
_mesa_share_state(struct gl_context *ctx, struct gl_context *ctxToShare)
{
   if (ctx && ctxToShare && ctx->Shared && ctxToShare->Shared) {
      struct gl_shared_state *oldShared = NULL;

      /* save ref to old state to prevent it from being deleted immediately */
      _mesa_reference_shared_state(ctx, &oldShared, ctx->Shared);

      /* update ctx's Shared pointer */
      _mesa_reference_shared_state(ctx, &ctx->Shared, ctxToShare->Shared);

      update_default_objects(ctx);

      /* release the old shared state */
      _mesa_reference_shared_state(ctx, &oldShared, NULL);

      return GL_TRUE;
   }
   else {
      return GL_FALSE;
   }
}



/**
 * \return pointer to the current GL context for this thread.
 * 
 * Calls _glapi_get_context(). This isn't the fastest way to get the current
 * context.  If you need speed, see the #GET_CURRENT_CONTEXT macro in
 * context.h.
 */
struct gl_context *
_mesa_get_current_context( void )
{
   return (struct gl_context *) _glapi_get_context();
}


/**
 * Get context's current API dispatch table.
 *
 * It'll either be the immediate-mode execute dispatcher or the display list
 * compile dispatcher.
 * 
 * \param ctx GL context.
 *
 * \return pointer to dispatch_table.
 *
 * Simply returns __struct gl_contextRec::CurrentDispatch.
 */
struct _glapi_table *
_mesa_get_dispatch(struct gl_context *ctx)
{
   return ctx->CurrentDispatch;
}

/*@}*/


/**********************************************************************/
/** \name Miscellaneous functions                                     */
/**********************************************************************/
/*@{*/

/**
 * Record an error.
 *
 * \param ctx GL context.
 * \param error error code.
 * 
 * Records the given error code and call the driver's dd_function_table::Error
 * function if defined.
 *
 * \sa
 * This is called via _mesa_error().
 */
void
_mesa_record_error(struct gl_context *ctx, GLenum error)
{
   if (!ctx)
      return;

   if (ctx->ErrorValue == GL_NO_ERROR) {
      ctx->ErrorValue = error;
   }
}


/**
 * Flush commands and wait for completion.
 */
void
_mesa_finish(struct gl_context *ctx)
{
   FLUSH_VERTICES( ctx, 0 );
   FLUSH_CURRENT( ctx, 0 );
   if (ctx->Driver.Finish) {
      ctx->Driver.Finish(ctx);
   }
}


/**
 * Flush commands.
 */
void
_mesa_flush(struct gl_context *ctx)
{
   FLUSH_VERTICES( ctx, 0 );
   FLUSH_CURRENT( ctx, 0 );
   if (ctx->Driver.Flush) {
      ctx->Driver.Flush(ctx);
   }
}



/**
 * Execute glFinish().
 *
 * Calls the #ASSERT_OUTSIDE_BEGIN_END_AND_FLUSH macro and the
 * dd_function_table::Finish driver callback, if not NULL.
 */
void GLAPIENTRY
_mesa_Finish(void)
{
   GET_CURRENT_CONTEXT(ctx);
   ASSERT_OUTSIDE_BEGIN_END(ctx);
   _mesa_finish(ctx);
}


/**
 * Execute glFlush().
 *
 * Calls the #ASSERT_OUTSIDE_BEGIN_END_AND_FLUSH macro and the
 * dd_function_table::Flush driver callback, if not NULL.
 */
void GLAPIENTRY
_mesa_Flush(void)
{
   GET_CURRENT_CONTEXT(ctx);
   ASSERT_OUTSIDE_BEGIN_END(ctx);
   _mesa_flush(ctx);
}


/*
 * ARB_blend_func_extended - ERRORS section
 * "The error INVALID_OPERATION is generated by Begin or any procedure that
 *  implicitly calls Begin if any draw buffer has a blend function requiring the
 *  second color input (SRC1_COLOR, ONE_MINUS_SRC1_COLOR, SRC1_ALPHA or
 *  ONE_MINUS_SRC1_ALPHA), and a framebuffer is bound that has more than
 *  the value of MAX_DUAL_SOURCE_DRAW_BUFFERS-1 active color attachements."
 */
static GLboolean
_mesa_check_blend_func_error(struct gl_context *ctx)
{
   GLuint i;
   for (i = ctx->Const.MaxDualSourceDrawBuffers;
	i < ctx->DrawBuffer->_NumColorDrawBuffers;
	i++) {
      if (ctx->Color.Blend[i]._UsesDualSrc) {
	 _mesa_error(ctx, GL_INVALID_OPERATION,
		     "dual source blend on illegal attachment");
	 return GL_FALSE;
      }
   }
   return GL_TRUE;
}

/**
 * Prior to drawing anything with glBegin, glDrawArrays, etc. this function
 * is called to see if it's valid to render.  This involves checking that
 * the current shader is valid and the framebuffer is complete.
 * If an error is detected it'll be recorded here.
 * \return GL_TRUE if OK to render, GL_FALSE if not
 */
GLboolean
_mesa_valid_to_render(struct gl_context *ctx, const char *where)
{
   bool vert_from_glsl_shader = false;
   bool geom_from_glsl_shader = false;
   bool frag_from_glsl_shader = false;

   /* This depends on having up to date derived state (shaders) */
   if (ctx->NewState)
      _mesa_update_state(ctx);

   if (ctx->Shader.CurrentProgram[MESA_SHADER_VERTEX]) {
      vert_from_glsl_shader = true;

      if (!ctx->Shader.CurrentProgram[MESA_SHADER_VERTEX]->LinkStatus) {
         _mesa_error(ctx, GL_INVALID_OPERATION,
                     "%s(shader not linked)", where);
         return GL_FALSE;
      }
#if 0 /* not normally enabled */
      {
         char errMsg[100];
         if (!_mesa_validate_shader_program(ctx,
					    ctx->Shader.CurrentProgram[MESA_SHADER_VERTEX],
                                            errMsg)) {
            _mesa_warning(ctx, "Shader program %u is invalid: %s",
                          ctx->Shader.CurrentProgram[MESA_SHADER_VERTEX]->Name, errMsg);
         }
      }
#endif
   }

   if (ctx->Shader.CurrentProgram[MESA_SHADER_GEOMETRY]) {
      geom_from_glsl_shader = true;

      if (!ctx->Shader.CurrentProgram[MESA_SHADER_GEOMETRY]->LinkStatus) {
         _mesa_error(ctx, GL_INVALID_OPERATION,
                     "%s(shader not linked)", where);
         return GL_FALSE;
      }
#if 0 /* not normally enabled */
      {
         char errMsg[100];
         if (!_mesa_validate_shader_program(ctx,
					    ctx->Shader.CurrentProgram[MESA_SHADER_GEOMETRY],
                                            errMsg)) {
            _mesa_warning(ctx, "Shader program %u is invalid: %s",
                          ctx->Shader.CurrentProgram[MESA_SHADER_GEOMETRY]->Name,
                          errMsg);
         }
      }
#endif
   }

   if (ctx->Shader.CurrentProgram[MESA_SHADER_FRAGMENT]) {
      frag_from_glsl_shader = true;

      if (!ctx->Shader.CurrentProgram[MESA_SHADER_FRAGMENT]->LinkStatus) {
         _mesa_error(ctx, GL_INVALID_OPERATION,
                     "%s(shader not linked)", where);
         return GL_FALSE;
      }
#if 0 /* not normally enabled */
      {
         char errMsg[100];
         if (!_mesa_validate_shader_program(ctx,
					    ctx->Shader.CurrentProgram[MESA_SHADER_FRAGMENT],
                                            errMsg)) {
            _mesa_warning(ctx, "Shader program %u is invalid: %s",
                          ctx->Shader.CurrentProgram[MESA_SHADER_FRAGMENT]->Name,
                          errMsg);
         }
      }
#endif
   }

   /* Any shader stages that are not supplied by the GLSL shader and have
    * assembly shaders enabled must now be validated.
    */
   if (!vert_from_glsl_shader
       && ctx->VertexProgram.Enabled && !ctx->VertexProgram._Enabled) {
      _mesa_error(ctx, GL_INVALID_OPERATION,
		  "%s(vertex program not valid)", where);
      return GL_FALSE;
   }

   /* FINISHME: If GL_NV_geometry_program4 is ever supported, the current
    * FINISHME: geometry program should validated here.
    */
   (void) geom_from_glsl_shader;

   if (!frag_from_glsl_shader) {
      if (ctx->FragmentProgram.Enabled && !ctx->FragmentProgram._Enabled) {
	 _mesa_error(ctx, GL_INVALID_OPERATION,
		     "%s(fragment program not valid)", where);
	 return GL_FALSE;
      }

      /* If drawing to integer-valued color buffers, there must be an
       * active fragment shader (GL_EXT_texture_integer).
       */
      if (ctx->DrawBuffer && ctx->DrawBuffer->_IntegerColor) {
         _mesa_error(ctx, GL_INVALID_OPERATION,
                     "%s(integer format but no fragment shader)", where);
         return GL_FALSE;
      }
   }

   if (ctx->DrawBuffer->_Status != GL_FRAMEBUFFER_COMPLETE_EXT) {
      _mesa_error(ctx, GL_INVALID_FRAMEBUFFER_OPERATION_EXT,
                  "%s(incomplete framebuffer)", where);
      return GL_FALSE;
   }

   if (_mesa_check_blend_func_error(ctx) == GL_FALSE) {
      return GL_FALSE;
   }

#ifdef DEBUG
   if (ctx->Shader.Flags & GLSL_LOG) {
      struct gl_shader_program **shProg = ctx->Shader.CurrentProgram;
      gl_shader_stage i;

      for (i = 0; i < MESA_SHADER_STAGES; i++) {
	 if (shProg[i] == NULL || shProg[i]->_Used
	     || shProg[i]->_LinkedShaders[i] == NULL)
	    continue;

	 /* This is the first time this shader is being used.
	  * Append shader's constants/uniforms to log file.
	  *
	  * Only log data for the program target that matches the shader
	  * target.  It's possible to have a program bound to the vertex
	  * shader target that also supplied a fragment shader.  If that
	  * program isn't also bound to the fragment shader target we don't
	  * want to log its fragment data.
	  */
	 _mesa_append_uniforms_to_file(shProg[i]->_LinkedShaders[i]);
      }

      for (i = 0; i < MESA_SHADER_STAGES; i++) {
	 if (shProg[i] != NULL)
	    shProg[i]->_Used = GL_TRUE;
      }
   }
#endif

   return GL_TRUE;
}


/*@}*/