summaryrefslogtreecommitdiffstats
path: root/src/gallium/docs/source/tgsi.rst
blob: cbb8f74ab895a18d64ca46bcce74f928d4e2a467 (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
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054
2055
2056
2057
2058
2059
2060
2061
2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095
2096
2097
2098
2099
2100
2101
2102
2103
2104
2105
2106
2107
2108
2109
2110
2111
2112
2113
2114
2115
2116
2117
2118
2119
2120
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
2133
2134
2135
2136
2137
2138
2139
2140
2141
2142
2143
2144
2145
2146
2147
2148
2149
2150
2151
2152
2153
2154
2155
2156
2157
2158
2159
2160
2161
2162
2163
2164
2165
2166
2167
2168
2169
2170
2171
2172
2173
2174
2175
2176
2177
2178
2179
2180
2181
2182
2183
2184
2185
2186
2187
2188
2189
2190
2191
2192
2193
2194
2195
2196
2197
2198
2199
2200
2201
2202
2203
2204
2205
2206
2207
2208
2209
2210
2211
2212
2213
2214
2215
2216
2217
2218
2219
2220
2221
2222
2223
2224
2225
2226
2227
2228
2229
2230
2231
2232
2233
2234
2235
2236
2237
2238
2239
2240
2241
2242
2243
2244
2245
2246
2247
2248
2249
2250
2251
2252
2253
2254
2255
2256
2257
2258
2259
2260
2261
2262
2263
2264
2265
2266
2267
2268
2269
2270
2271
2272
2273
2274
2275
2276
2277
2278
2279
2280
2281
2282
2283
2284
2285
2286
2287
2288
2289
2290
2291
2292
2293
2294
2295
2296
2297
2298
2299
2300
2301
2302
2303
2304
2305
2306
2307
2308
2309
2310
2311
2312
2313
2314
2315
2316
2317
2318
2319
2320
2321
2322
2323
2324
2325
2326
2327
2328
2329
2330
2331
2332
2333
2334
2335
2336
2337
2338
2339
2340
2341
2342
2343
2344
2345
2346
2347
2348
2349
2350
2351
2352
2353
2354
2355
2356
2357
2358
2359
2360
2361
2362
2363
2364
2365
2366
2367
2368
2369
2370
2371
2372
2373
2374
2375
2376
2377
2378
2379
2380
2381
2382
2383
2384
2385
2386
2387
2388
2389
2390
2391
2392
2393
2394
2395
2396
2397
2398
2399
2400
2401
2402
2403
2404
2405
2406
2407
2408
2409
2410
2411
2412
2413
2414
2415
2416
2417
2418
2419
2420
2421
2422
2423
2424
2425
2426
2427
2428
2429
2430
2431
2432
2433
2434
2435
2436
2437
2438
2439
2440
2441
2442
2443
2444
2445
2446
2447
2448
2449
2450
2451
2452
2453
2454
2455
2456
2457
2458
2459
2460
2461
2462
2463
2464
2465
2466
2467
2468
2469
2470
2471
2472
2473
2474
2475
2476
2477
2478
2479
2480
2481
2482
2483
2484
2485
2486
2487
2488
2489
2490
2491
2492
2493
2494
2495
2496
2497
2498
2499
2500
2501
2502
2503
2504
2505
2506
2507
2508
2509
2510
2511
2512
2513
2514
2515
2516
2517
2518
2519
2520
2521
2522
2523
2524
2525
2526
2527
2528
2529
2530
2531
2532
2533
2534
2535
2536
2537
2538
2539
2540
2541
2542
2543
2544
2545
2546
2547
2548
2549
2550
2551
2552
2553
2554
2555
2556
2557
2558
2559
2560
2561
2562
2563
2564
2565
2566
2567
2568
2569
2570
2571
2572
2573
2574
2575
2576
2577
2578
2579
2580
2581
2582
2583
2584
2585
2586
2587
2588
2589
2590
2591
2592
2593
2594
2595
2596
2597
2598
2599
2600
2601
2602
2603
2604
2605
2606
2607
2608
2609
2610
2611
2612
2613
2614
2615
2616
2617
2618
2619
2620
2621
2622
2623
2624
2625
2626
2627
2628
2629
2630
2631
2632
2633
2634
2635
2636
2637
2638
2639
2640
2641
2642
2643
2644
2645
2646
2647
2648
2649
2650
2651
2652
2653
2654
2655
2656
2657
2658
2659
2660
2661
2662
2663
2664
2665
2666
2667
2668
2669
2670
2671
2672
2673
2674
2675
2676
2677
2678
2679
2680
2681
2682
2683
2684
2685
2686
2687
2688
2689
2690
2691
2692
2693
2694
2695
2696
2697
2698
2699
2700
2701
2702
2703
2704
2705
2706
2707
2708
2709
2710
2711
2712
2713
2714
2715
2716
2717
2718
2719
2720
2721
2722
2723
2724
2725
2726
2727
2728
2729
2730
2731
2732
2733
2734
2735
2736
2737
2738
2739
2740
2741
2742
2743
2744
2745
2746
2747
2748
2749
2750
2751
2752
2753
2754
2755
2756
2757
2758
2759
2760
2761
2762
2763
2764
2765
2766
2767
2768
2769
2770
2771
2772
2773
2774
2775
2776
2777
2778
2779
2780
2781
2782
2783
2784
2785
2786
2787
2788
2789
2790
2791
2792
2793
2794
2795
2796
2797
2798
2799
2800
2801
2802
2803
2804
2805
2806
2807
2808
2809
2810
2811
2812
2813
2814
2815
2816
2817
2818
2819
2820
2821
2822
2823
2824
2825
2826
2827
2828
2829
2830
2831
2832
2833
2834
2835
2836
2837
2838
2839
2840
2841
2842
2843
2844
2845
2846
2847
2848
2849
2850
2851
2852
2853
2854
2855
2856
2857
2858
2859
2860
2861
2862
2863
2864
2865
2866
2867
2868
2869
2870
2871
2872
2873
2874
2875
2876
2877
2878
2879
2880
2881
2882
2883
2884
2885
2886
2887
2888
2889
2890
2891
2892
2893
2894
2895
2896
2897
2898
2899
2900
2901
2902
2903
2904
TGSI
====

TGSI, Tungsten Graphics Shader Infrastructure, is an intermediate language
for describing shaders. Since Gallium is inherently shaderful, shaders are
an important part of the API. TGSI is the only intermediate representation
used by all drivers.

Basics
------

All TGSI instructions, known as *opcodes*, operate on arbitrary-precision
floating-point four-component vectors. An opcode may have up to one
destination register, known as *dst*, and between zero and three source
registers, called *src0* through *src2*, or simply *src* if there is only
one.

Some instructions, like :opcode:`I2F`, permit re-interpretation of vector
components as integers. Other instructions permit using registers as
two-component vectors with double precision; see :ref:`doubleopcodes`.

When an instruction has a scalar result, the result is usually copied into
each of the components of *dst*. When this happens, the result is said to be
*replicated* to *dst*. :opcode:`RCP` is one such instruction.

Modifiers
^^^^^^^^^^^^^^^

TGSI supports modifiers on inputs (as well as saturate modifier on instructions).

For inputs which have a floating point type, both absolute value and negation
modifiers are supported (with absolute value being applied first).
TGSI_OPCODE_MOV is considered to have float input type for applying modifiers.

For inputs which have signed or unsigned type only the negate modifier is
supported.

Instruction Set
---------------

Core ISA
^^^^^^^^^^^^^^^^^^^^^^^^^

These opcodes are guaranteed to be available regardless of the driver being
used.

.. opcode:: ARL - Address Register Load

.. math::

  dst.x = \lfloor src.x\rfloor

  dst.y = \lfloor src.y\rfloor

  dst.z = \lfloor src.z\rfloor

  dst.w = \lfloor src.w\rfloor


.. opcode:: MOV - Move

.. math::

  dst.x = src.x

  dst.y = src.y

  dst.z = src.z

  dst.w = src.w


.. opcode:: LIT - Light Coefficients

.. math::

  dst.x &= 1 \\
  dst.y &= max(src.x, 0) \\
  dst.z &= (src.x > 0) ? max(src.y, 0)^{clamp(src.w, -128, 128))} : 0 \\
  dst.w &= 1


.. opcode:: RCP - Reciprocal

This instruction replicates its result.

.. math::

  dst = \frac{1}{src.x}


.. opcode:: RSQ - Reciprocal Square Root

This instruction replicates its result. The results are undefined for src <= 0.

.. math::

  dst = \frac{1}{\sqrt{src.x}}


.. opcode:: SQRT - Square Root

This instruction replicates its result. The results are undefined for src < 0.

.. math::

  dst = {\sqrt{src.x}}


.. opcode:: EXP - Approximate Exponential Base 2

.. math::

  dst.x &= 2^{\lfloor src.x\rfloor} \\
  dst.y &= src.x - \lfloor src.x\rfloor \\
  dst.z &= 2^{src.x} \\
  dst.w &= 1


.. opcode:: LOG - Approximate Logarithm Base 2

.. math::

  dst.x &= \lfloor\log_2{|src.x|}\rfloor \\
  dst.y &= \frac{|src.x|}{2^{\lfloor\log_2{|src.x|}\rfloor}} \\
  dst.z &= \log_2{|src.x|} \\
  dst.w &= 1


.. opcode:: MUL - Multiply

.. math::

  dst.x = src0.x \times src1.x

  dst.y = src0.y \times src1.y

  dst.z = src0.z \times src1.z

  dst.w = src0.w \times src1.w


.. opcode:: ADD - Add

.. math::

  dst.x = src0.x + src1.x

  dst.y = src0.y + src1.y

  dst.z = src0.z + src1.z

  dst.w = src0.w + src1.w


.. opcode:: DP3 - 3-component Dot Product

This instruction replicates its result.

.. math::

  dst = src0.x \times src1.x + src0.y \times src1.y + src0.z \times src1.z


.. opcode:: DP4 - 4-component Dot Product

This instruction replicates its result.

.. math::

  dst = src0.x \times src1.x + src0.y \times src1.y + src0.z \times src1.z + src0.w \times src1.w


.. opcode:: DST - Distance Vector

.. math::

  dst.x &= 1\\
  dst.y &= src0.y \times src1.y\\
  dst.z &= src0.z\\
  dst.w &= src1.w


.. opcode:: MIN - Minimum

.. math::

  dst.x = min(src0.x, src1.x)

  dst.y = min(src0.y, src1.y)

  dst.z = min(src0.z, src1.z)

  dst.w = min(src0.w, src1.w)


.. opcode:: MAX - Maximum

.. math::

  dst.x = max(src0.x, src1.x)

  dst.y = max(src0.y, src1.y)

  dst.z = max(src0.z, src1.z)

  dst.w = max(src0.w, src1.w)


.. opcode:: SLT - Set On Less Than

.. math::

  dst.x = (src0.x < src1.x) ? 1.0F : 0.0F

  dst.y = (src0.y < src1.y) ? 1.0F : 0.0F

  dst.z = (src0.z < src1.z) ? 1.0F : 0.0F

  dst.w = (src0.w < src1.w) ? 1.0F : 0.0F


.. opcode:: SGE - Set On Greater Equal Than

.. math::

  dst.x = (src0.x >= src1.x) ? 1.0F : 0.0F

  dst.y = (src0.y >= src1.y) ? 1.0F : 0.0F

  dst.z = (src0.z >= src1.z) ? 1.0F : 0.0F

  dst.w = (src0.w >= src1.w) ? 1.0F : 0.0F


.. opcode:: MAD - Multiply And Add

.. math::

  dst.x = src0.x \times src1.x + src2.x

  dst.y = src0.y \times src1.y + src2.y

  dst.z = src0.z \times src1.z + src2.z

  dst.w = src0.w \times src1.w + src2.w


.. opcode:: SUB - Subtract

.. math::

  dst.x = src0.x - src1.x

  dst.y = src0.y - src1.y

  dst.z = src0.z - src1.z

  dst.w = src0.w - src1.w


.. opcode:: LRP - Linear Interpolate

.. math::

  dst.x = src0.x \times src1.x + (1 - src0.x) \times src2.x

  dst.y = src0.y \times src1.y + (1 - src0.y) \times src2.y

  dst.z = src0.z \times src1.z + (1 - src0.z) \times src2.z

  dst.w = src0.w \times src1.w + (1 - src0.w) \times src2.w


.. opcode:: DP2A - 2-component Dot Product And Add

.. math::

  dst.x = src0.x \times src1.x + src0.y \times src1.y + src2.x

  dst.y = src0.x \times src1.x + src0.y \times src1.y + src2.x

  dst.z = src0.x \times src1.x + src0.y \times src1.y + src2.x

  dst.w = src0.x \times src1.x + src0.y \times src1.y + src2.x


.. opcode:: FRC - Fraction

.. math::

  dst.x = src.x - \lfloor src.x\rfloor

  dst.y = src.y - \lfloor src.y\rfloor

  dst.z = src.z - \lfloor src.z\rfloor

  dst.w = src.w - \lfloor src.w\rfloor


.. opcode:: CLAMP - Clamp

.. math::

  dst.x = clamp(src0.x, src1.x, src2.x)

  dst.y = clamp(src0.y, src1.y, src2.y)

  dst.z = clamp(src0.z, src1.z, src2.z)

  dst.w = clamp(src0.w, src1.w, src2.w)


.. opcode:: FLR - Floor

This is identical to :opcode:`ARL`.

.. math::

  dst.x = \lfloor src.x\rfloor

  dst.y = \lfloor src.y\rfloor

  dst.z = \lfloor src.z\rfloor

  dst.w = \lfloor src.w\rfloor


.. opcode:: ROUND - Round

.. math::

  dst.x = round(src.x)

  dst.y = round(src.y)

  dst.z = round(src.z)

  dst.w = round(src.w)


.. opcode:: EX2 - Exponential Base 2

This instruction replicates its result.

.. math::

  dst = 2^{src.x}


.. opcode:: LG2 - Logarithm Base 2

This instruction replicates its result.

.. math::

  dst = \log_2{src.x}


.. opcode:: POW - Power

This instruction replicates its result.

.. math::

  dst = src0.x^{src1.x}

.. opcode:: XPD - Cross Product

.. math::

  dst.x = src0.y \times src1.z - src1.y \times src0.z

  dst.y = src0.z \times src1.x - src1.z \times src0.x

  dst.z = src0.x \times src1.y - src1.x \times src0.y

  dst.w = 1


.. opcode:: ABS - Absolute

.. math::

  dst.x = |src.x|

  dst.y = |src.y|

  dst.z = |src.z|

  dst.w = |src.w|


.. opcode:: DPH - Homogeneous Dot Product

This instruction replicates its result.

.. math::

  dst = src0.x \times src1.x + src0.y \times src1.y + src0.z \times src1.z + src1.w


.. opcode:: COS - Cosine

This instruction replicates its result.

.. math::

  dst = \cos{src.x}


.. opcode:: DDX, DDX_FINE - Derivative Relative To X

The fine variant is only used when ``PIPE_CAP_TGSI_FS_FINE_DERIVATIVE`` is
advertised. When it is, the fine version guarantees one derivative per row
while DDX is allowed to be the same for the entire 2x2 quad.

.. math::

  dst.x = partialx(src.x)

  dst.y = partialx(src.y)

  dst.z = partialx(src.z)

  dst.w = partialx(src.w)


.. opcode:: DDY, DDY_FINE - Derivative Relative To Y

The fine variant is only used when ``PIPE_CAP_TGSI_FS_FINE_DERIVATIVE`` is
advertised. When it is, the fine version guarantees one derivative per column
while DDY is allowed to be the same for the entire 2x2 quad.

.. math::

  dst.x = partialy(src.x)

  dst.y = partialy(src.y)

  dst.z = partialy(src.z)

  dst.w = partialy(src.w)


.. opcode:: PK2H - Pack Two 16-bit Floats

  TBD


.. opcode:: PK2US - Pack Two Unsigned 16-bit Scalars

  TBD


.. opcode:: PK4B - Pack Four Signed 8-bit Scalars

  TBD


.. opcode:: PK4UB - Pack Four Unsigned 8-bit Scalars

  TBD


.. opcode:: SEQ - Set On Equal

.. math::

  dst.x = (src0.x == src1.x) ? 1.0F : 0.0F

  dst.y = (src0.y == src1.y) ? 1.0F : 0.0F

  dst.z = (src0.z == src1.z) ? 1.0F : 0.0F

  dst.w = (src0.w == src1.w) ? 1.0F : 0.0F


.. opcode:: SGT - Set On Greater Than

.. math::

  dst.x = (src0.x > src1.x) ? 1.0F : 0.0F

  dst.y = (src0.y > src1.y) ? 1.0F : 0.0F

  dst.z = (src0.z > src1.z) ? 1.0F : 0.0F

  dst.w = (src0.w > src1.w) ? 1.0F : 0.0F


.. opcode:: SIN - Sine

This instruction replicates its result.

.. math::

  dst = \sin{src.x}


.. opcode:: SLE - Set On Less Equal Than

.. math::

  dst.x = (src0.x <= src1.x) ? 1.0F : 0.0F

  dst.y = (src0.y <= src1.y) ? 1.0F : 0.0F

  dst.z = (src0.z <= src1.z) ? 1.0F : 0.0F

  dst.w = (src0.w <= src1.w) ? 1.0F : 0.0F


.. opcode:: SNE - Set On Not Equal

.. math::

  dst.x = (src0.x != src1.x) ? 1.0F : 0.0F

  dst.y = (src0.y != src1.y) ? 1.0F : 0.0F

  dst.z = (src0.z != src1.z) ? 1.0F : 0.0F

  dst.w = (src0.w != src1.w) ? 1.0F : 0.0F


.. opcode:: TEX - Texture Lookup

  for array textures src0.y contains the slice for 1D,
  and src0.z contain the slice for 2D.

  for shadow textures with no arrays (and not cube map),
  src0.z contains the reference value.

  for shadow textures with arrays, src0.z contains
  the reference value for 1D arrays, and src0.w contains
  the reference value for 2D arrays and cube maps.

  for cube map array shadow textures, the reference value
  cannot be passed in src0.w, and TEX2 must be used instead.

.. math::

  coord = src0

  shadow_ref = src0.z or src0.w (optional)

  unit = src1

  dst = texture\_sample(unit, coord, shadow_ref)


.. opcode:: TEX2 - Texture Lookup (for shadow cube map arrays only)

  this is the same as TEX, but uses another reg to encode the
  reference value.

.. math::

  coord = src0

  shadow_ref = src1.x

  unit = src2

  dst = texture\_sample(unit, coord, shadow_ref)




.. opcode:: TXD - Texture Lookup with Derivatives

.. math::

  coord = src0

  ddx = src1

  ddy = src2

  unit = src3

  dst = texture\_sample\_deriv(unit, coord, ddx, ddy)


.. opcode:: TXP - Projective Texture Lookup

.. math::

  coord.x = src0.x / src0.w

  coord.y = src0.y / src0.w

  coord.z = src0.z / src0.w

  coord.w = src0.w

  unit = src1

  dst = texture\_sample(unit, coord)


.. opcode:: UP2H - Unpack Two 16-Bit Floats

  TBD

.. note::

   Considered for removal.

.. opcode:: UP2US - Unpack Two Unsigned 16-Bit Scalars

  TBD

.. note::

   Considered for removal.

.. opcode:: UP4B - Unpack Four Signed 8-Bit Values

  TBD

.. note::

   Considered for removal.

.. opcode:: UP4UB - Unpack Four Unsigned 8-Bit Scalars

  TBD

.. note::

   Considered for removal.


.. opcode:: ARR - Address Register Load With Round

.. math::

  dst.x = round(src.x)

  dst.y = round(src.y)

  dst.z = round(src.z)

  dst.w = round(src.w)


.. opcode:: SSG - Set Sign

.. math::

  dst.x = (src.x > 0) ? 1 : (src.x < 0) ? -1 : 0

  dst.y = (src.y > 0) ? 1 : (src.y < 0) ? -1 : 0

  dst.z = (src.z > 0) ? 1 : (src.z < 0) ? -1 : 0

  dst.w = (src.w > 0) ? 1 : (src.w < 0) ? -1 : 0


.. opcode:: CMP - Compare

.. math::

  dst.x = (src0.x < 0) ? src1.x : src2.x

  dst.y = (src0.y < 0) ? src1.y : src2.y

  dst.z = (src0.z < 0) ? src1.z : src2.z

  dst.w = (src0.w < 0) ? src1.w : src2.w


.. opcode:: KILL_IF - Conditional Discard

  Conditional discard.  Allowed in fragment shaders only.

.. math::

  if (src.x < 0 || src.y < 0 || src.z < 0 || src.w < 0)
    discard
  endif


.. opcode:: KILL - Discard

  Unconditional discard.  Allowed in fragment shaders only.


.. opcode:: SCS - Sine Cosine

.. math::

  dst.x = \cos{src.x}

  dst.y = \sin{src.x}

  dst.z = 0

  dst.w = 1


.. opcode:: TXB - Texture Lookup With Bias

  for cube map array textures and shadow cube maps, the bias value
  cannot be passed in src0.w, and TXB2 must be used instead.

  if the target is a shadow texture, the reference value is always
  in src.z (this prevents shadow 3d and shadow 2d arrays from
  using this instruction, but this is not needed).

.. math::

  coord.x = src0.x

  coord.y = src0.y

  coord.z = src0.z

  coord.w = none

  bias = src0.w

  unit = src1

  dst = texture\_sample(unit, coord, bias)


.. opcode:: TXB2 - Texture Lookup With Bias (some cube maps only)

  this is the same as TXB, but uses another reg to encode the
  lod bias value for cube map arrays and shadow cube maps.
  Presumably shadow 2d arrays and shadow 3d targets could use
  this encoding too, but this is not legal.

  shadow cube map arrays are neither possible nor required.

.. math::

  coord = src0

  bias = src1.x

  unit = src2

  dst = texture\_sample(unit, coord, bias)


.. opcode:: DIV - Divide

.. math::

  dst.x = \frac{src0.x}{src1.x}

  dst.y = \frac{src0.y}{src1.y}

  dst.z = \frac{src0.z}{src1.z}

  dst.w = \frac{src0.w}{src1.w}


.. opcode:: DP2 - 2-component Dot Product

This instruction replicates its result.

.. math::

  dst = src0.x \times src1.x + src0.y \times src1.y


.. opcode:: TXL - Texture Lookup With explicit LOD

  for cube map array textures, the explicit lod value
  cannot be passed in src0.w, and TXL2 must be used instead.

  if the target is a shadow texture, the reference value is always
  in src.z (this prevents shadow 3d / 2d array / cube targets from
  using this instruction, but this is not needed).

.. math::

  coord.x = src0.x

  coord.y = src0.y

  coord.z = src0.z

  coord.w = none

  lod = src0.w

  unit = src1

  dst = texture\_sample(unit, coord, lod)


.. opcode:: TXL2 - Texture Lookup With explicit LOD (for cube map arrays only)

  this is the same as TXL, but uses another reg to encode the
  explicit lod value.
  Presumably shadow 3d / 2d array / cube targets could use
  this encoding too, but this is not legal.

  shadow cube map arrays are neither possible nor required.

.. math::

  coord = src0

  lod = src1.x

  unit = src2

  dst = texture\_sample(unit, coord, lod)


.. opcode:: PUSHA - Push Address Register On Stack

  push(src.x)
  push(src.y)
  push(src.z)
  push(src.w)

.. note::

   Considered for cleanup.

.. note::

   Considered for removal.

.. opcode:: POPA - Pop Address Register From Stack

  dst.w = pop()
  dst.z = pop()
  dst.y = pop()
  dst.x = pop()

.. note::

   Considered for cleanup.

.. note::

   Considered for removal.


.. opcode:: CALLNZ - Subroutine Call If Not Zero

   TBD

.. note::

   Considered for cleanup.

.. note::

   Considered for removal.


Compute ISA
^^^^^^^^^^^^^^^^^^^^^^^^

These opcodes are primarily provided for special-use computational shaders.
Support for these opcodes indicated by a special pipe capability bit (TBD).

XXX doesn't look like most of the opcodes really belong here.

.. opcode:: CEIL - Ceiling

.. math::

  dst.x = \lceil src.x\rceil

  dst.y = \lceil src.y\rceil

  dst.z = \lceil src.z\rceil

  dst.w = \lceil src.w\rceil


.. opcode:: TRUNC - Truncate

.. math::

  dst.x = trunc(src.x)

  dst.y = trunc(src.y)

  dst.z = trunc(src.z)

  dst.w = trunc(src.w)


.. opcode:: MOD - Modulus

.. math::

  dst.x = src0.x \bmod src1.x

  dst.y = src0.y \bmod src1.y

  dst.z = src0.z \bmod src1.z

  dst.w = src0.w \bmod src1.w


.. opcode:: UARL - Integer Address Register Load

  Moves the contents of the source register, assumed to be an integer, into the
  destination register, which is assumed to be an address (ADDR) register.


.. opcode:: SAD - Sum Of Absolute Differences

.. math::

  dst.x = |src0.x - src1.x| + src2.x

  dst.y = |src0.y - src1.y| + src2.y

  dst.z = |src0.z - src1.z| + src2.z

  dst.w = |src0.w - src1.w| + src2.w


.. opcode:: TXF - Texel Fetch

  As per NV_gpu_shader4, extract a single texel from a specified texture
  image. The source sampler may not be a CUBE or SHADOW.  src 0 is a
  four-component signed integer vector used to identify the single texel
  accessed. 3 components + level.  Just like texture instructions, an optional
  offset vector is provided, which is subject to various driver restrictions
  (regarding range, source of offsets).
  TXF(uint_vec coord, int_vec offset).


.. opcode:: TXQ - Texture Size Query

  As per NV_gpu_program4, retrieve the dimensions of the texture depending on
  the target. For 1D (width), 2D/RECT/CUBE (width, height), 3D (width, height,
  depth), 1D array (width, layers), 2D array (width, height, layers).
  Also return the number of accessible levels (last_level - first_level + 1)
  in W.

  For components which don't return a resource dimension, their value
  is undefined.


.. math::

  lod = src0.x

  dst.x = texture\_width(unit, lod)

  dst.y = texture\_height(unit, lod)

  dst.z = texture\_depth(unit, lod)

  dst.w = texture\_levels(unit)

.. opcode:: TG4 - Texture Gather

  As per ARB_texture_gather, gathers the four texels to be used in a bi-linear
  filtering operation and packs them into a single register.  Only works with
  2D, 2D array, cubemaps, and cubemaps arrays.  For 2D textures, only the
  addressing modes of the sampler and the top level of any mip pyramid are
  used. Set W to zero.  It behaves like the TEX instruction, but a filtered
  sample is not generated. The four samples that contribute to filtering are
  placed into xyzw in clockwise order, starting with the (u,v) texture
  coordinate delta at the following locations (-, +), (+, +), (+, -), (-, -),
  where the magnitude of the deltas are half a texel.

  PIPE_CAP_TEXTURE_SM5 enhances this instruction to support shadow per-sample
  depth compares, single component selection, and a non-constant offset. It
  doesn't allow support for the GL independent offset to get i0,j0. This would
  require another CAP is hw can do it natively. For now we lower that before
  TGSI.

.. math::

   coord = src0

   component = src1

   dst = texture\_gather4 (unit, coord, component)

(with SM5 - cube array shadow)

.. math::

   coord = src0

   compare = src1

   dst = texture\_gather (uint, coord, compare)

.. opcode:: LODQ - level of detail query

   Compute the LOD information that the texture pipe would use to access the
   texture. The Y component contains the computed LOD lambda_prime. The X
   component contains the LOD that will be accessed, based on min/max lod's
   and mipmap filters.

.. math::

   coord = src0

   dst.xy = lodq(uint, coord);

Integer ISA
^^^^^^^^^^^^^^^^^^^^^^^^
These opcodes are used for integer operations.
Support for these opcodes indicated by PIPE_SHADER_CAP_INTEGERS (all of them?)


.. opcode:: I2F - Signed Integer To Float

   Rounding is unspecified (round to nearest even suggested).

.. math::

  dst.x = (float) src.x

  dst.y = (float) src.y

  dst.z = (float) src.z

  dst.w = (float) src.w


.. opcode:: U2F - Unsigned Integer To Float

   Rounding is unspecified (round to nearest even suggested).

.. math::

  dst.x = (float) src.x

  dst.y = (float) src.y

  dst.z = (float) src.z

  dst.w = (float) src.w


.. opcode:: F2I - Float to Signed Integer

   Rounding is towards zero (truncate).
   Values outside signed range (including NaNs) produce undefined results.

.. math::

  dst.x = (int) src.x

  dst.y = (int) src.y

  dst.z = (int) src.z

  dst.w = (int) src.w


.. opcode:: F2U - Float to Unsigned Integer

   Rounding is towards zero (truncate).
   Values outside unsigned range (including NaNs) produce undefined results.

.. math::

  dst.x = (unsigned) src.x

  dst.y = (unsigned) src.y

  dst.z = (unsigned) src.z

  dst.w = (unsigned) src.w


.. opcode:: UADD - Integer Add

   This instruction works the same for signed and unsigned integers.
   The low 32bit of the result is returned.

.. math::

  dst.x = src0.x + src1.x

  dst.y = src0.y + src1.y

  dst.z = src0.z + src1.z

  dst.w = src0.w + src1.w


.. opcode:: UMAD - Integer Multiply And Add

   This instruction works the same for signed and unsigned integers.
   The multiplication returns the low 32bit (as does the result itself).

.. math::

  dst.x = src0.x \times src1.x + src2.x

  dst.y = src0.y \times src1.y + src2.y

  dst.z = src0.z \times src1.z + src2.z

  dst.w = src0.w \times src1.w + src2.w


.. opcode:: UMUL - Integer Multiply

   This instruction works the same for signed and unsigned integers.
   The low 32bit of the result is returned.

.. math::

  dst.x = src0.x \times src1.x

  dst.y = src0.y \times src1.y

  dst.z = src0.z \times src1.z

  dst.w = src0.w \times src1.w


.. opcode:: IMUL_HI - Signed Integer Multiply High Bits

   The high 32bits of the multiplication of 2 signed integers are returned.

.. math::

  dst.x = (src0.x \times src1.x) >> 32

  dst.y = (src0.y \times src1.y) >> 32

  dst.z = (src0.z \times src1.z) >> 32

  dst.w = (src0.w \times src1.w) >> 32


.. opcode:: UMUL_HI - Unsigned Integer Multiply High Bits

   The high 32bits of the multiplication of 2 unsigned integers are returned.

.. math::

  dst.x = (src0.x \times src1.x) >> 32

  dst.y = (src0.y \times src1.y) >> 32

  dst.z = (src0.z \times src1.z) >> 32

  dst.w = (src0.w \times src1.w) >> 32


.. opcode:: IDIV - Signed Integer Division

   TBD: behavior for division by zero.

.. math::

  dst.x = src0.x \ src1.x

  dst.y = src0.y \ src1.y

  dst.z = src0.z \ src1.z

  dst.w = src0.w \ src1.w


.. opcode:: UDIV - Unsigned Integer Division

   For division by zero, 0xffffffff is returned.

.. math::

  dst.x = src0.x \ src1.x

  dst.y = src0.y \ src1.y

  dst.z = src0.z \ src1.z

  dst.w = src0.w \ src1.w


.. opcode:: UMOD - Unsigned Integer Remainder

   If second arg is zero, 0xffffffff is returned.

.. math::

  dst.x = src0.x \ src1.x

  dst.y = src0.y \ src1.y

  dst.z = src0.z \ src1.z

  dst.w = src0.w \ src1.w


.. opcode:: NOT - Bitwise Not

.. math::

  dst.x = \sim src.x

  dst.y = \sim src.y

  dst.z = \sim src.z

  dst.w = \sim src.w


.. opcode:: AND - Bitwise And

.. math::

  dst.x = src0.x \& src1.x

  dst.y = src0.y \& src1.y

  dst.z = src0.z \& src1.z

  dst.w = src0.w \& src1.w


.. opcode:: OR - Bitwise Or

.. math::

  dst.x = src0.x | src1.x

  dst.y = src0.y | src1.y

  dst.z = src0.z | src1.z

  dst.w = src0.w | src1.w


.. opcode:: XOR - Bitwise Xor

.. math::

  dst.x = src0.x \oplus src1.x

  dst.y = src0.y \oplus src1.y

  dst.z = src0.z \oplus src1.z

  dst.w = src0.w \oplus src1.w


.. opcode:: IMAX - Maximum of Signed Integers

.. math::

  dst.x = max(src0.x, src1.x)

  dst.y = max(src0.y, src1.y)

  dst.z = max(src0.z, src1.z)

  dst.w = max(src0.w, src1.w)


.. opcode:: UMAX - Maximum of Unsigned Integers

.. math::

  dst.x = max(src0.x, src1.x)

  dst.y = max(src0.y, src1.y)

  dst.z = max(src0.z, src1.z)

  dst.w = max(src0.w, src1.w)


.. opcode:: IMIN - Minimum of Signed Integers

.. math::

  dst.x = min(src0.x, src1.x)

  dst.y = min(src0.y, src1.y)

  dst.z = min(src0.z, src1.z)

  dst.w = min(src0.w, src1.w)


.. opcode:: UMIN - Minimum of Unsigned Integers

.. math::

  dst.x = min(src0.x, src1.x)

  dst.y = min(src0.y, src1.y)

  dst.z = min(src0.z, src1.z)

  dst.w = min(src0.w, src1.w)


.. opcode:: SHL - Shift Left

   The shift count is masked with 0x1f before the shift is applied.

.. math::

  dst.x = src0.x << (0x1f \& src1.x)

  dst.y = src0.y << (0x1f \& src1.y)

  dst.z = src0.z << (0x1f \& src1.z)

  dst.w = src0.w << (0x1f \& src1.w)


.. opcode:: ISHR - Arithmetic Shift Right (of Signed Integer)

   The shift count is masked with 0x1f before the shift is applied.

.. math::

  dst.x = src0.x >> (0x1f \& src1.x)

  dst.y = src0.y >> (0x1f \& src1.y)

  dst.z = src0.z >> (0x1f \& src1.z)

  dst.w = src0.w >> (0x1f \& src1.w)


.. opcode:: USHR - Logical Shift Right

   The shift count is masked with 0x1f before the shift is applied.

.. math::

  dst.x = src0.x >> (unsigned) (0x1f \& src1.x)

  dst.y = src0.y >> (unsigned) (0x1f \& src1.y)

  dst.z = src0.z >> (unsigned) (0x1f \& src1.z)

  dst.w = src0.w >> (unsigned) (0x1f \& src1.w)


.. opcode:: UCMP - Integer Conditional Move

.. math::

  dst.x = src0.x ? src1.x : src2.x

  dst.y = src0.y ? src1.y : src2.y

  dst.z = src0.z ? src1.z : src2.z

  dst.w = src0.w ? src1.w : src2.w



.. opcode:: ISSG - Integer Set Sign

.. math::

  dst.x = (src0.x < 0) ? -1 : (src0.x > 0) ? 1 : 0

  dst.y = (src0.y < 0) ? -1 : (src0.y > 0) ? 1 : 0

  dst.z = (src0.z < 0) ? -1 : (src0.z > 0) ? 1 : 0

  dst.w = (src0.w < 0) ? -1 : (src0.w > 0) ? 1 : 0



.. opcode:: FSLT - Float Set On Less Than (ordered)

   Same comparison as SLT but returns integer instead of 1.0/0.0 float

.. math::

  dst.x = (src0.x < src1.x) ? \sim 0 : 0

  dst.y = (src0.y < src1.y) ? \sim 0 : 0

  dst.z = (src0.z < src1.z) ? \sim 0 : 0

  dst.w = (src0.w < src1.w) ? \sim 0 : 0


.. opcode:: ISLT - Signed Integer Set On Less Than

.. math::

  dst.x = (src0.x < src1.x) ? \sim 0 : 0

  dst.y = (src0.y < src1.y) ? \sim 0 : 0

  dst.z = (src0.z < src1.z) ? \sim 0 : 0

  dst.w = (src0.w < src1.w) ? \sim 0 : 0


.. opcode:: USLT - Unsigned Integer Set On Less Than

.. math::

  dst.x = (src0.x < src1.x) ? \sim 0 : 0

  dst.y = (src0.y < src1.y) ? \sim 0 : 0

  dst.z = (src0.z < src1.z) ? \sim 0 : 0

  dst.w = (src0.w < src1.w) ? \sim 0 : 0


.. opcode:: FSGE - Float Set On Greater Equal Than (ordered)

   Same comparison as SGE but returns integer instead of 1.0/0.0 float

.. math::

  dst.x = (src0.x >= src1.x) ? \sim 0 : 0

  dst.y = (src0.y >= src1.y) ? \sim 0 : 0

  dst.z = (src0.z >= src1.z) ? \sim 0 : 0

  dst.w = (src0.w >= src1.w) ? \sim 0 : 0


.. opcode:: ISGE - Signed Integer Set On Greater Equal Than

.. math::

  dst.x = (src0.x >= src1.x) ? \sim 0 : 0

  dst.y = (src0.y >= src1.y) ? \sim 0 : 0

  dst.z = (src0.z >= src1.z) ? \sim 0 : 0

  dst.w = (src0.w >= src1.w) ? \sim 0 : 0


.. opcode:: USGE - Unsigned Integer Set On Greater Equal Than

.. math::

  dst.x = (src0.x >= src1.x) ? \sim 0 : 0

  dst.y = (src0.y >= src1.y) ? \sim 0 : 0

  dst.z = (src0.z >= src1.z) ? \sim 0 : 0

  dst.w = (src0.w >= src1.w) ? \sim 0 : 0


.. opcode:: FSEQ - Float Set On Equal (ordered)

   Same comparison as SEQ but returns integer instead of 1.0/0.0 float

.. math::

  dst.x = (src0.x == src1.x) ? \sim 0 : 0

  dst.y = (src0.y == src1.y) ? \sim 0 : 0

  dst.z = (src0.z == src1.z) ? \sim 0 : 0

  dst.w = (src0.w == src1.w) ? \sim 0 : 0


.. opcode:: USEQ - Integer Set On Equal

.. math::

  dst.x = (src0.x == src1.x) ? \sim 0 : 0

  dst.y = (src0.y == src1.y) ? \sim 0 : 0

  dst.z = (src0.z == src1.z) ? \sim 0 : 0

  dst.w = (src0.w == src1.w) ? \sim 0 : 0


.. opcode:: FSNE - Float Set On Not Equal (unordered)

   Same comparison as SNE but returns integer instead of 1.0/0.0 float

.. math::

  dst.x = (src0.x != src1.x) ? \sim 0 : 0

  dst.y = (src0.y != src1.y) ? \sim 0 : 0

  dst.z = (src0.z != src1.z) ? \sim 0 : 0

  dst.w = (src0.w != src1.w) ? \sim 0 : 0


.. opcode:: USNE - Integer Set On Not Equal

.. math::

  dst.x = (src0.x != src1.x) ? \sim 0 : 0

  dst.y = (src0.y != src1.y) ? \sim 0 : 0

  dst.z = (src0.z != src1.z) ? \sim 0 : 0

  dst.w = (src0.w != src1.w) ? \sim 0 : 0


.. opcode:: INEG - Integer Negate

  Two's complement.

.. math::

  dst.x = -src.x

  dst.y = -src.y

  dst.z = -src.z

  dst.w = -src.w


.. opcode:: IABS - Integer Absolute Value

.. math::

  dst.x = |src.x|

  dst.y = |src.y|

  dst.z = |src.z|

  dst.w = |src.w|

Bitwise ISA
^^^^^^^^^^^
These opcodes are used for bit-level manipulation of integers.

.. opcode:: IBFE - Signed Bitfield Extract

  See SM5 instruction of the same name. Extracts a set of bits from the input,
  and sign-extends them if the high bit of the extracted window is set.

  Pseudocode::

    def ibfe(value, offset, bits):
      offset = offset & 0x1f
      bits = bits & 0x1f
      if bits == 0: return 0
      # Note: >> sign-extends
      if width + offset < 32:
        return (value << (32 - offset - bits)) >> (32 - bits)
      else:
        return value >> offset

.. opcode:: UBFE - Unsigned Bitfield Extract

  See SM5 instruction of the same name. Extracts a set of bits from the input,
  without any sign-extension.

  Pseudocode::

    def ubfe(value, offset, bits):
      offset = offset & 0x1f
      bits = bits & 0x1f
      if bits == 0: return 0
      # Note: >> does not sign-extend
      if width + offset < 32:
        return (value << (32 - offset - bits)) >> (32 - bits)
      else:
        return value >> offset

.. opcode:: BFI - Bitfield Insert

  See SM5 instruction of the same name. Replaces a bit region of 'base' with
  the low bits of 'insert'.

  Pseudocode::

    def bfi(base, insert, offset, bits):
      offset = offset & 0x1f
      bits = bits & 0x1f
      mask = ((1 << bits) - 1) << offset
      return ((insert << offset) & mask) | (base & ~mask)

.. opcode:: BREV - Bitfield Reverse

  See SM5 instruction BFREV. Reverses the bits of the argument.

.. opcode:: POPC - Population Count

  See SM5 instruction COUNTBITS. Counts the number of set bits in the argument.

.. opcode:: LSB - Index of lowest set bit

  See SM5 instruction FIRSTBIT_LO. Computes the 0-based index of the first set
  bit of the argument. Returns -1 if none are set.

.. opcode:: IMSB - Index of highest non-sign bit

  See SM5 instruction FIRSTBIT_SHI. Computes the 0-based index of the highest
  non-sign bit of the argument (i.e. highest 0 bit for negative numbers,
  highest 1 bit for positive numbers). Returns -1 if all bits are the same
  (i.e. for inputs 0 and -1).

.. opcode:: UMSB - Index of highest set bit

  See SM5 instruction FIRSTBIT_HI. Computes the 0-based index of the highest
  set bit of the argument. Returns -1 if none are set.

Geometry ISA
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

These opcodes are only supported in geometry shaders; they have no meaning
in any other type of shader.

.. opcode:: EMIT - Emit

  Generate a new vertex for the current primitive into the specified vertex
  stream using the values in the output registers.


.. opcode:: ENDPRIM - End Primitive

  Complete the current primitive in the specified vertex stream (consisting of
  the emitted vertices), and start a new one.


GLSL ISA
^^^^^^^^^^

These opcodes are part of :term:`GLSL`'s opcode set. Support for these
opcodes is determined by a special capability bit, ``GLSL``.
Some require glsl version 1.30 (UIF/BREAKC/SWITCH/CASE/DEFAULT/ENDSWITCH).

.. opcode:: CAL - Subroutine Call

  push(pc)
  pc = target


.. opcode:: RET - Subroutine Call Return

  pc = pop()


.. opcode:: CONT - Continue

  Unconditionally moves the point of execution to the instruction after the
  last bgnloop. The instruction must appear within a bgnloop/endloop.

.. note::

   Support for CONT is determined by a special capability bit,
   ``TGSI_CONT_SUPPORTED``. See :ref:`Screen` for more information.


.. opcode:: BGNLOOP - Begin a Loop

  Start a loop. Must have a matching endloop.


.. opcode:: BGNSUB - Begin Subroutine

  Starts definition of a subroutine. Must have a matching endsub.


.. opcode:: ENDLOOP - End a Loop

  End a loop started with bgnloop.


.. opcode:: ENDSUB - End Subroutine

  Ends definition of a subroutine.


.. opcode:: NOP - No Operation

  Do nothing.


.. opcode:: BRK - Break

  Unconditionally moves the point of execution to the instruction after the
  next endloop or endswitch. The instruction must appear within a loop/endloop
  or switch/endswitch.


.. opcode:: BREAKC - Break Conditional

  Conditionally moves the point of execution to the instruction after the
  next endloop or endswitch. The instruction must appear within a loop/endloop
  or switch/endswitch.
  Condition evaluates to true if src0.x != 0 where src0.x is interpreted
  as an integer register.

.. note::

   Considered for removal as it's quite inconsistent wrt other opcodes
   (could emulate with UIF/BRK/ENDIF). 


.. opcode:: IF - Float If

  Start an IF ... ELSE .. ENDIF block.  Condition evaluates to true if

    src0.x != 0.0

  where src0.x is interpreted as a floating point register.


.. opcode:: UIF - Bitwise If

  Start an UIF ... ELSE .. ENDIF block. Condition evaluates to true if

    src0.x != 0

  where src0.x is interpreted as an integer register.


.. opcode:: ELSE - Else

  Starts an else block, after an IF or UIF statement.


.. opcode:: ENDIF - End If

  Ends an IF or UIF block.


.. opcode:: SWITCH - Switch

   Starts a C-style switch expression. The switch consists of one or multiple
   CASE statements, and at most one DEFAULT statement. Execution of a statement
   ends when a BRK is hit, but just like in C falling through to other cases
   without a break is allowed. Similarly, DEFAULT label is allowed anywhere not
   just as last statement, and fallthrough is allowed into/from it.
   CASE src arguments are evaluated at bit level against the SWITCH src argument.

   Example::

     SWITCH src[0].x
     CASE src[0].x
     (some instructions here)
     (optional BRK here)
     DEFAULT
     (some instructions here)
     (optional BRK here)
     CASE src[0].x
     (some instructions here)
     (optional BRK here)
     ENDSWITCH


.. opcode:: CASE - Switch case

   This represents a switch case label. The src arg must be an integer immediate.


.. opcode:: DEFAULT - Switch default

   This represents the default case in the switch, which is taken if no other
   case matches.


.. opcode:: ENDSWITCH - End of switch

   Ends a switch expression.


Interpolation ISA
^^^^^^^^^^^^^^^^^

The interpolation instructions allow an input to be interpolated in a
different way than its declaration. This corresponds to the GLSL 4.00
interpolateAt* functions. The first argument of each of these must come from
``TGSI_FILE_INPUT``.

.. opcode:: INTERP_CENTROID - Interpolate at the centroid

   Interpolates the varying specified by src0 at the centroid

.. opcode:: INTERP_SAMPLE - Interpolate at the specified sample

   Interpolates the varying specified by src0 at the sample id specified by
   src1.x (interpreted as an integer)

.. opcode:: INTERP_OFFSET - Interpolate at the specified offset

   Interpolates the varying specified by src0 at the offset src1.xy from the
   pixel center (interpreted as floats)


.. _doubleopcodes:

Double ISA
^^^^^^^^^^^^^^^

The double-precision opcodes reinterpret four-component vectors into
two-component vectors with doubled precision in each component.

Support for these opcodes is XXX undecided. :T

.. opcode:: DADD - Add

.. math::

  dst.xy = src0.xy + src1.xy

  dst.zw = src0.zw + src1.zw


.. opcode:: DDIV - Divide

.. math::

  dst.xy = src0.xy / src1.xy

  dst.zw = src0.zw / src1.zw

.. opcode:: DSEQ - Set on Equal

.. math::

  dst.xy = src0.xy == src1.xy ? 1.0F : 0.0F

  dst.zw = src0.zw == src1.zw ? 1.0F : 0.0F

.. opcode:: DSLT - Set on Less than

.. math::

  dst.xy = src0.xy < src1.xy ? 1.0F : 0.0F

  dst.zw = src0.zw < src1.zw ? 1.0F : 0.0F

.. opcode:: DFRAC - Fraction

.. math::

  dst.xy = src.xy - \lfloor src.xy\rfloor

  dst.zw = src.zw - \lfloor src.zw\rfloor


.. opcode:: DFRACEXP - Convert Number to Fractional and Integral Components

Like the ``frexp()`` routine in many math libraries, this opcode stores the
exponent of its source to ``dst0``, and the significand to ``dst1``, such that
:math:`dst1 \times 2^{dst0} = src` .

.. math::

  dst0.xy = exp(src.xy)

  dst1.xy = frac(src.xy)

  dst0.zw = exp(src.zw)

  dst1.zw = frac(src.zw)

.. opcode:: DLDEXP - Multiply Number by Integral Power of 2

This opcode is the inverse of :opcode:`DFRACEXP`.

.. math::

  dst.xy = src0.xy \times 2^{src1.xy}

  dst.zw = src0.zw \times 2^{src1.zw}

.. opcode:: DMIN - Minimum

.. math::

  dst.xy = min(src0.xy, src1.xy)

  dst.zw = min(src0.zw, src1.zw)

.. opcode:: DMAX - Maximum

.. math::

  dst.xy = max(src0.xy, src1.xy)

  dst.zw = max(src0.zw, src1.zw)

.. opcode:: DMUL - Multiply

.. math::

  dst.xy = src0.xy \times src1.xy

  dst.zw = src0.zw \times src1.zw


.. opcode:: DMAD - Multiply And Add

.. math::

  dst.xy = src0.xy \times src1.xy + src2.xy

  dst.zw = src0.zw \times src1.zw + src2.zw


.. opcode:: DRCP - Reciprocal

.. math::

   dst.xy = \frac{1}{src.xy}

   dst.zw = \frac{1}{src.zw}

.. opcode:: DSQRT - Square Root

.. math::

   dst.xy = \sqrt{src.xy}

   dst.zw = \sqrt{src.zw}


.. _samplingopcodes:

Resource Sampling Opcodes
^^^^^^^^^^^^^^^^^^^^^^^^^

Those opcodes follow very closely semantics of the respective Direct3D
instructions. If in doubt double check Direct3D documentation.
Note that the swizzle on SVIEW (src1) determines texel swizzling
after lookup.

.. opcode:: SAMPLE

  Using provided address, sample data from the specified texture using the
  filtering mode identified by the gven sampler. The source data may come from
  any resource type other than buffers.

  Syntax: ``SAMPLE dst, address, sampler_view, sampler``

  Example: ``SAMPLE TEMP[0], TEMP[1], SVIEW[0], SAMP[0]``

.. opcode:: SAMPLE_I

  Simplified alternative to the SAMPLE instruction.  Using the provided
  integer address, SAMPLE_I fetches data from the specified sampler view
  without any filtering.  The source data may come from any resource type
  other than CUBE.

  Syntax: ``SAMPLE_I dst, address, sampler_view``

  Example: ``SAMPLE_I TEMP[0], TEMP[1], SVIEW[0]``

  The 'address' is specified as unsigned integers. If the 'address' is out of
  range [0...(# texels - 1)] the result of the fetch is always 0 in all
  components.  As such the instruction doesn't honor address wrap modes, in
  cases where that behavior is desirable 'SAMPLE' instruction should be used.
  address.w always provides an unsigned integer mipmap level. If the value is
  out of the range then the instruction always returns 0 in all components.
  address.yz are ignored for buffers and 1d textures.  address.z is ignored
  for 1d texture arrays and 2d textures.

  For 1D texture arrays address.y provides the array index (also as unsigned
  integer). If the value is out of the range of available array indices
  [0... (array size - 1)] then the opcode always returns 0 in all components.
  For 2D texture arrays address.z provides the array index, otherwise it
  exhibits the same behavior as in the case for 1D texture arrays.  The exact
  semantics of the source address are presented in the table below:

  +---------------------------+----+-----+-----+---------+
  | resource type             | X  |  Y  |  Z  |    W    |
  +===========================+====+=====+=====+=========+
  | ``PIPE_BUFFER``           | x  |     |     | ignored |
  +---------------------------+----+-----+-----+---------+
  | ``PIPE_TEXTURE_1D``       | x  |     |     |   mpl   |
  +---------------------------+----+-----+-----+---------+
  | ``PIPE_TEXTURE_2D``       | x  |  y  |     |   mpl   |
  +---------------------------+----+-----+-----+---------+
  | ``PIPE_TEXTURE_3D``       | x  |  y  |  z  |   mpl   |
  +---------------------------+----+-----+-----+---------+
  | ``PIPE_TEXTURE_RECT``     | x  |  y  |     |   mpl   |
  +---------------------------+----+-----+-----+---------+
  | ``PIPE_TEXTURE_CUBE``     | not allowed as source    |
  +---------------------------+----+-----+-----+---------+
  | ``PIPE_TEXTURE_1D_ARRAY`` | x  | idx |     |   mpl   |
  +---------------------------+----+-----+-----+---------+
  | ``PIPE_TEXTURE_2D_ARRAY`` | x  |  y  | idx |   mpl   |
  +---------------------------+----+-----+-----+---------+

  Where 'mpl' is a mipmap level and 'idx' is the array index.

.. opcode:: SAMPLE_I_MS

  Just like SAMPLE_I but allows fetch data from multi-sampled surfaces.

  Syntax: ``SAMPLE_I_MS dst, address, sampler_view, sample``

.. opcode:: SAMPLE_B

  Just like the SAMPLE instruction with the exception that an additional bias
  is applied to the level of detail computed as part of the instruction
  execution.

  Syntax: ``SAMPLE_B dst, address, sampler_view, sampler, lod_bias``

  Example: ``SAMPLE_B TEMP[0], TEMP[1], SVIEW[0], SAMP[0], TEMP[2].x``

.. opcode:: SAMPLE_C

  Similar to the SAMPLE instruction but it performs a comparison filter. The
  operands to SAMPLE_C are identical to SAMPLE, except that there is an
  additional float32 operand, reference value, which must be a register with
  single-component, or a scalar literal.  SAMPLE_C makes the hardware use the
  current samplers compare_func (in pipe_sampler_state) to compare reference
  value against the red component value for the surce resource at each texel
  that the currently configured texture filter covers based on the provided
  coordinates.

  Syntax: ``SAMPLE_C dst, address, sampler_view.r, sampler, ref_value``

  Example: ``SAMPLE_C TEMP[0], TEMP[1], SVIEW[0].r, SAMP[0], TEMP[2].x``

.. opcode:: SAMPLE_C_LZ

  Same as SAMPLE_C, but LOD is 0 and derivatives are ignored. The LZ stands
  for level-zero.

  Syntax: ``SAMPLE_C_LZ dst, address, sampler_view.r, sampler, ref_value``

  Example: ``SAMPLE_C_LZ TEMP[0], TEMP[1], SVIEW[0].r, SAMP[0], TEMP[2].x``


.. opcode:: SAMPLE_D

  SAMPLE_D is identical to the SAMPLE opcode except that the derivatives for
  the source address in the x direction and the y direction are provided by
  extra parameters.

  Syntax: ``SAMPLE_D dst, address, sampler_view, sampler, der_x, der_y``

  Example: ``SAMPLE_D TEMP[0], TEMP[1], SVIEW[0], SAMP[0], TEMP[2], TEMP[3]``

.. opcode:: SAMPLE_L

  SAMPLE_L is identical to the SAMPLE opcode except that the LOD is provided
  directly as a scalar value, representing no anisotropy.

  Syntax: ``SAMPLE_L dst, address, sampler_view, sampler, explicit_lod``

  Example: ``SAMPLE_L TEMP[0], TEMP[1], SVIEW[0], SAMP[0], TEMP[2].x``

.. opcode:: GATHER4

  Gathers the four texels to be used in a bi-linear filtering operation and
  packs them into a single register.  Only works with 2D, 2D array, cubemaps,
  and cubemaps arrays.  For 2D textures, only the addressing modes of the
  sampler and the top level of any mip pyramid are used. Set W to zero.  It
  behaves like the SAMPLE instruction, but a filtered sample is not
  generated. The four samples that contribute to filtering are placed into
  xyzw in counter-clockwise order, starting with the (u,v) texture coordinate
  delta at the following locations (-, +), (+, +), (+, -), (-, -), where the
  magnitude of the deltas are half a texel.


.. opcode:: SVIEWINFO

  Query the dimensions of a given sampler view.  dst receives width, height,
  depth or array size and number of mipmap levels as int4. The dst can have a
  writemask which will specify what info is the caller interested in.

  Syntax: ``SVIEWINFO dst, src_mip_level, sampler_view``

  Example: ``SVIEWINFO TEMP[0], TEMP[1].x, SVIEW[0]``

  src_mip_level is an unsigned integer scalar. If it's out of range then
  returns 0 for width, height and depth/array size but the total number of
  mipmap is still returned correctly for the given sampler view.  The returned
  width, height and depth values are for the mipmap level selected by the
  src_mip_level and are in the number of texels.  For 1d texture array width
  is in dst.x, array size is in dst.y and dst.z is 0. The number of mipmaps is
  still in dst.w.  In contrast to d3d10 resinfo, there's no way in the tgsi
  instruction encoding to specify the return type (float/rcpfloat/uint), hence
  always using uint. Also, unlike the SAMPLE instructions, the swizzle on src1
  resinfo allowing swizzling dst values is ignored (due to the interaction
  with rcpfloat modifier which requires some swizzle handling in the state
  tracker anyway).

.. opcode:: SAMPLE_POS

  Query the position of a given sample.  dst receives float4 (x, y, 0, 0)
  indicated where the sample is located. If the resource is not a multi-sample
  resource and not a render target, the result is 0.

.. opcode:: SAMPLE_INFO

  dst receives number of samples in x.  If the resource is not a multi-sample
  resource and not a render target, the result is 0.


.. _resourceopcodes:

Resource Access Opcodes
^^^^^^^^^^^^^^^^^^^^^^^

.. opcode:: LOAD - Fetch data from a shader resource

               Syntax: ``LOAD dst, resource, address``

               Example: ``LOAD TEMP[0], RES[0], TEMP[1]``

               Using the provided integer address, LOAD fetches data
               from the specified buffer or texture without any
               filtering.

               The 'address' is specified as a vector of unsigned
               integers.  If the 'address' is out of range the result
               is unspecified.

               Only the first mipmap level of a resource can be read
               from using this instruction.

               For 1D or 2D texture arrays, the array index is
               provided as an unsigned integer in address.y or
               address.z, respectively.  address.yz are ignored for
               buffers and 1D textures.  address.z is ignored for 1D
               texture arrays and 2D textures.  address.w is always
               ignored.

.. opcode:: STORE - Write data to a shader resource

               Syntax: ``STORE resource, address, src``

               Example: ``STORE RES[0], TEMP[0], TEMP[1]``

               Using the provided integer address, STORE writes data
               to the specified buffer or texture.

               The 'address' is specified as a vector of unsigned
               integers.  If the 'address' is out of range the result
               is unspecified.

               Only the first mipmap level of a resource can be
               written to using this instruction.

               For 1D or 2D texture arrays, the array index is
               provided as an unsigned integer in address.y or
               address.z, respectively.  address.yz are ignored for
               buffers and 1D textures.  address.z is ignored for 1D
               texture arrays and 2D textures.  address.w is always
               ignored.


.. _threadsyncopcodes:

Inter-thread synchronization opcodes
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

These opcodes are intended for communication between threads running
within the same compute grid.  For now they're only valid in compute
programs.

.. opcode:: MFENCE - Memory fence

  Syntax: ``MFENCE resource``

  Example: ``MFENCE RES[0]``

  This opcode forces strong ordering between any memory access
  operations that affect the specified resource.  This means that
  previous loads and stores (and only those) will be performed and
  visible to other threads before the program execution continues.


.. opcode:: LFENCE - Load memory fence

  Syntax: ``LFENCE resource``

  Example: ``LFENCE RES[0]``

  Similar to MFENCE, but it only affects the ordering of memory loads.


.. opcode:: SFENCE - Store memory fence

  Syntax: ``SFENCE resource``

  Example: ``SFENCE RES[0]``

  Similar to MFENCE, but it only affects the ordering of memory stores.


.. opcode:: BARRIER - Thread group barrier

  ``BARRIER``

  This opcode suspends the execution of the current thread until all
  the remaining threads in the working group reach the same point of
  the program.  Results are unspecified if any of the remaining
  threads terminates or never reaches an executed BARRIER instruction.


.. _atomopcodes:

Atomic opcodes
^^^^^^^^^^^^^^

These opcodes provide atomic variants of some common arithmetic and
logical operations.  In this context atomicity means that another
concurrent memory access operation that affects the same memory
location is guaranteed to be performed strictly before or after the
entire execution of the atomic operation.

For the moment they're only valid in compute programs.

.. opcode:: ATOMUADD - Atomic integer addition

  Syntax: ``ATOMUADD dst, resource, offset, src``

  Example: ``ATOMUADD TEMP[0], RES[0], TEMP[1], TEMP[2]``

  The following operation is performed atomically on each component:

.. math::

  dst_i = resource[offset]_i

  resource[offset]_i = dst_i + src_i


.. opcode:: ATOMXCHG - Atomic exchange

  Syntax: ``ATOMXCHG dst, resource, offset, src``

  Example: ``ATOMXCHG TEMP[0], RES[0], TEMP[1], TEMP[2]``

  The following operation is performed atomically on each component:

.. math::

  dst_i = resource[offset]_i

  resource[offset]_i = src_i


.. opcode:: ATOMCAS - Atomic compare-and-exchange

  Syntax: ``ATOMCAS dst, resource, offset, cmp, src``

  Example: ``ATOMCAS TEMP[0], RES[0], TEMP[1], TEMP[2], TEMP[3]``

  The following operation is performed atomically on each component:

.. math::

  dst_i = resource[offset]_i

  resource[offset]_i = (dst_i == cmp_i ? src_i : dst_i)


.. opcode:: ATOMAND - Atomic bitwise And

  Syntax: ``ATOMAND dst, resource, offset, src``

  Example: ``ATOMAND TEMP[0], RES[0], TEMP[1], TEMP[2]``

  The following operation is performed atomically on each component:

.. math::

  dst_i = resource[offset]_i

  resource[offset]_i = dst_i \& src_i


.. opcode:: ATOMOR - Atomic bitwise Or

  Syntax: ``ATOMOR dst, resource, offset, src``

  Example: ``ATOMOR TEMP[0], RES[0], TEMP[1], TEMP[2]``

  The following operation is performed atomically on each component:

.. math::

  dst_i = resource[offset]_i

  resource[offset]_i = dst_i | src_i


.. opcode:: ATOMXOR - Atomic bitwise Xor

  Syntax: ``ATOMXOR dst, resource, offset, src``

  Example: ``ATOMXOR TEMP[0], RES[0], TEMP[1], TEMP[2]``

  The following operation is performed atomically on each component:

.. math::

  dst_i = resource[offset]_i

  resource[offset]_i = dst_i \oplus src_i


.. opcode:: ATOMUMIN - Atomic unsigned minimum

  Syntax: ``ATOMUMIN dst, resource, offset, src``

  Example: ``ATOMUMIN TEMP[0], RES[0], TEMP[1], TEMP[2]``

  The following operation is performed atomically on each component:

.. math::

  dst_i = resource[offset]_i

  resource[offset]_i = (dst_i < src_i ? dst_i : src_i)


.. opcode:: ATOMUMAX - Atomic unsigned maximum

  Syntax: ``ATOMUMAX dst, resource, offset, src``

  Example: ``ATOMUMAX TEMP[0], RES[0], TEMP[1], TEMP[2]``

  The following operation is performed atomically on each component:

.. math::

  dst_i = resource[offset]_i

  resource[offset]_i = (dst_i > src_i ? dst_i : src_i)


.. opcode:: ATOMIMIN - Atomic signed minimum

  Syntax: ``ATOMIMIN dst, resource, offset, src``

  Example: ``ATOMIMIN TEMP[0], RES[0], TEMP[1], TEMP[2]``

  The following operation is performed atomically on each component:

.. math::

  dst_i = resource[offset]_i

  resource[offset]_i = (dst_i < src_i ? dst_i : src_i)


.. opcode:: ATOMIMAX - Atomic signed maximum

  Syntax: ``ATOMIMAX dst, resource, offset, src``

  Example: ``ATOMIMAX TEMP[0], RES[0], TEMP[1], TEMP[2]``

  The following operation is performed atomically on each component:

.. math::

  dst_i = resource[offset]_i

  resource[offset]_i = (dst_i > src_i ? dst_i : src_i)



Explanation of symbols used
------------------------------


Functions
^^^^^^^^^^^^^^


  :math:`|x|`       Absolute value of `x`.

  :math:`\lceil x \rceil` Ceiling of `x`.

  clamp(x,y,z)      Clamp x between y and z.
                    (x < y) ? y : (x > z) ? z : x

  :math:`\lfloor x\rfloor` Floor of `x`.

  :math:`\log_2{x}` Logarithm of `x`, base 2.

  max(x,y)          Maximum of x and y.
                    (x > y) ? x : y

  min(x,y)          Minimum of x and y.
                    (x < y) ? x : y

  partialx(x)       Derivative of x relative to fragment's X.

  partialy(x)       Derivative of x relative to fragment's Y.

  pop()             Pop from stack.

  :math:`x^y`       `x` to the power `y`.

  push(x)           Push x on stack.

  round(x)          Round x.

  trunc(x)          Truncate x, i.e. drop the fraction bits.


Keywords
^^^^^^^^^^^^^


  discard           Discard fragment.

  pc                Program counter.

  target            Label of target instruction.


Other tokens
---------------


Declaration
^^^^^^^^^^^


Declares a register that is will be referenced as an operand in Instruction
tokens.

File field contains register file that is being declared and is one
of TGSI_FILE.

UsageMask field specifies which of the register components can be accessed
and is one of TGSI_WRITEMASK.

The Local flag specifies that a given value isn't intended for
subroutine parameter passing and, as a result, the implementation
isn't required to give any guarantees of it being preserved across
subroutine boundaries.  As it's merely a compiler hint, the
implementation is free to ignore it.

If Dimension flag is set to 1, a Declaration Dimension token follows.

If Semantic flag is set to 1, a Declaration Semantic token follows.

If Interpolate flag is set to 1, a Declaration Interpolate token follows.

If file is TGSI_FILE_RESOURCE, a Declaration Resource token follows.

If Array flag is set to 1, a Declaration Array token follows.

Array Declaration
^^^^^^^^^^^^^^^^^^^^^^^^

Declarations can optional have an ArrayID attribute which can be referred by
indirect addressing operands. An ArrayID of zero is reserved and treaded as
if no ArrayID is specified.

If an indirect addressing operand refers to a specific declaration by using
an ArrayID only the registers in this declaration are guaranteed to be
accessed, accessing any register outside this declaration results in undefined
behavior. Note that for compatibility the effective index is zero-based and
not relative to the specified declaration

If no ArrayID is specified with an indirect addressing operand the whole
register file might be accessed by this operand. This is strongly discouraged
and will prevent packing of scalar/vec2 arrays and effective alias analysis.

Declaration Semantic
^^^^^^^^^^^^^^^^^^^^^^^^

Vertex and fragment shader input and output registers may be labeled
with semantic information consisting of a name and index.

Follows Declaration token if Semantic bit is set.

Since its purpose is to link a shader with other stages of the pipeline,
it is valid to follow only those Declaration tokens that declare a register
either in INPUT or OUTPUT file.

SemanticName field contains the semantic name of the register being declared.
There is no default value.

SemanticIndex is an optional subscript that can be used to distinguish
different register declarations with the same semantic name. The default value
is 0.

The meanings of the individual semantic names are explained in the following
sections.

TGSI_SEMANTIC_POSITION
""""""""""""""""""""""

For vertex shaders, TGSI_SEMANTIC_POSITION indicates the vertex shader
output register which contains the homogeneous vertex position in the clip
space coordinate system.  After clipping, the X, Y and Z components of the
vertex will be divided by the W value to get normalized device coordinates.

For fragment shaders, TGSI_SEMANTIC_POSITION is used to indicate that
fragment shader input contains the fragment's window position.  The X
component starts at zero and always increases from left to right.
The Y component starts at zero and always increases but Y=0 may either
indicate the top of the window or the bottom depending on the fragment
coordinate origin convention (see TGSI_PROPERTY_FS_COORD_ORIGIN).
The Z coordinate ranges from 0 to 1 to represent depth from the front
to the back of the Z buffer.  The W component contains the interpolated
reciprocal of the vertex position W component (corresponding to gl_Fragcoord,
but unlike d3d10 which interpolates the same 1/w but then gives back
the reciprocal of the interpolated value).

Fragment shaders may also declare an output register with
TGSI_SEMANTIC_POSITION.  Only the Z component is writable.  This allows
the fragment shader to change the fragment's Z position.



TGSI_SEMANTIC_COLOR
"""""""""""""""""""

For vertex shader outputs or fragment shader inputs/outputs, this
label indicates that the resister contains an R,G,B,A color.

Several shader inputs/outputs may contain colors so the semantic index
is used to distinguish them.  For example, color[0] may be the diffuse
color while color[1] may be the specular color.

This label is needed so that the flat/smooth shading can be applied
to the right interpolants during rasterization.



TGSI_SEMANTIC_BCOLOR
""""""""""""""""""""

Back-facing colors are only used for back-facing polygons, and are only valid
in vertex shader outputs. After rasterization, all polygons are front-facing
and COLOR and BCOLOR end up occupying the same slots in the fragment shader,
so all BCOLORs effectively become regular COLORs in the fragment shader.


TGSI_SEMANTIC_FOG
"""""""""""""""""

Vertex shader inputs and outputs and fragment shader inputs may be
labeled with TGSI_SEMANTIC_FOG to indicate that the register contains
a fog coordinate.  Typically, the fragment shader will use the fog coordinate
to compute a fog blend factor which is used to blend the normal fragment color
with a constant fog color.  But fog coord really is just an ordinary vec4
register like regular semantics.


TGSI_SEMANTIC_PSIZE
"""""""""""""""""""

Vertex shader input and output registers may be labeled with
TGIS_SEMANTIC_PSIZE to indicate that the register contains a point size
in the form (S, 0, 0, 1).  The point size controls the width or diameter
of points for rasterization.  This label cannot be used in fragment
shaders.

When using this semantic, be sure to set the appropriate state in the
:ref:`rasterizer` first.


TGSI_SEMANTIC_TEXCOORD
""""""""""""""""""""""

Only available if PIPE_CAP_TGSI_TEXCOORD is exposed !

Vertex shader outputs and fragment shader inputs may be labeled with
this semantic to make them replaceable by sprite coordinates via the
sprite_coord_enable state in the :ref:`rasterizer`.
The semantic index permitted with this semantic is limited to <= 7.

If the driver does not support TEXCOORD, sprite coordinate replacement
applies to inputs with the GENERIC semantic instead.

The intended use case for this semantic is gl_TexCoord.


TGSI_SEMANTIC_PCOORD
""""""""""""""""""""

Only available if PIPE_CAP_TGSI_TEXCOORD is exposed !

Fragment shader inputs may be labeled with TGSI_SEMANTIC_PCOORD to indicate
that the register contains sprite coordinates in the form (x, y, 0, 1), if
the current primitive is a point and point sprites are enabled. Otherwise,
the contents of the register are undefined.

The intended use case for this semantic is gl_PointCoord.


TGSI_SEMANTIC_GENERIC
"""""""""""""""""""""

All vertex/fragment shader inputs/outputs not labeled with any other
semantic label can be considered to be generic attributes.  Typical
uses of generic inputs/outputs are texcoords and user-defined values.


TGSI_SEMANTIC_NORMAL
""""""""""""""""""""

Indicates that a vertex shader input is a normal vector.  This is
typically only used for legacy graphics APIs.


TGSI_SEMANTIC_FACE
""""""""""""""""""

This label applies to fragment shader inputs only and indicates that
the register contains front/back-face information of the form (F, 0,
0, 1).  The first component will be positive when the fragment belongs
to a front-facing polygon, and negative when the fragment belongs to a
back-facing polygon.


TGSI_SEMANTIC_EDGEFLAG
""""""""""""""""""""""

For vertex shaders, this sematic label indicates that an input or
output is a boolean edge flag.  The register layout is [F, x, x, x]
where F is 0.0 or 1.0 and x = don't care.  Normally, the vertex shader
simply copies the edge flag input to the edgeflag output.

Edge flags are used to control which lines or points are actually
drawn when the polygon mode converts triangles/quads/polygons into
points or lines.


TGSI_SEMANTIC_STENCIL
"""""""""""""""""""""

For fragment shaders, this semantic label indicates that an output
is a writable stencil reference value. Only the Y component is writable.
This allows the fragment shader to change the fragments stencilref value.


TGSI_SEMANTIC_VIEWPORT_INDEX
""""""""""""""""""""""""""""

For geometry shaders, this semantic label indicates that an output
contains the index of the viewport (and scissor) to use.
Only the X value is used.


TGSI_SEMANTIC_LAYER
"""""""""""""""""""

For geometry shaders, this semantic label indicates that an output
contains the layer value to use for the color and depth/stencil surfaces.
Only the X value is used. (Also known as rendertarget array index.)


TGSI_SEMANTIC_CULLDIST
""""""""""""""""""""""

Used as distance to plane for performing application-defined culling
of individual primitives against a plane. When components of vertex
elements are given this label, these values are assumed to be a
float32 signed distance to a plane. Primitives will be completely
discarded if the plane distance for all of the vertices in the
primitive are < 0. If a vertex has a cull distance of NaN, that
vertex counts as "out" (as if its < 0);
The limits on both clip and cull distances are bound
by the PIPE_MAX_CLIP_OR_CULL_DISTANCE_COUNT define which defines
the maximum number of components that can be used to hold the
distances and by the PIPE_MAX_CLIP_OR_CULL_DISTANCE_ELEMENT_COUNT
which specifies the maximum number of registers which can be
annotated with those semantics.


TGSI_SEMANTIC_CLIPDIST
""""""""""""""""""""""

When components of vertex elements are identified this way, these
values are each assumed to be a float32 signed distance to a plane.
Primitive setup only invokes rasterization on pixels for which
the interpolated plane distances are >= 0. Multiple clip planes
can be implemented simultaneously, by annotating multiple
components of one or more vertex elements with the above specified
semantic. The limits on both clip and cull distances are bound
by the PIPE_MAX_CLIP_OR_CULL_DISTANCE_COUNT define which defines
the maximum number of components that can be used to hold the
distances and by the PIPE_MAX_CLIP_OR_CULL_DISTANCE_ELEMENT_COUNT
which specifies the maximum number of registers which can be
annotated with those semantics.

TGSI_SEMANTIC_SAMPLEID
""""""""""""""""""""""

For fragment shaders, this semantic label indicates that a system value
contains the current sample id (i.e. gl_SampleID). Only the X value is used.

TGSI_SEMANTIC_SAMPLEPOS
"""""""""""""""""""""""

For fragment shaders, this semantic label indicates that a system value
contains the current sample's position (i.e. gl_SamplePosition). Only the X
and Y values are used.

TGSI_SEMANTIC_SAMPLEMASK
""""""""""""""""""""""""

For fragment shaders, this semantic label indicates that an output contains
the sample mask used to disable further sample processing
(i.e. gl_SampleMask). Only the X value is used, up to 32x MS.

TGSI_SEMANTIC_INVOCATIONID
""""""""""""""""""""""""""

For geometry shaders, this semantic label indicates that a system value
contains the current invocation id (i.e. gl_InvocationID). Only the X value is
used.

Declaration Interpolate
^^^^^^^^^^^^^^^^^^^^^^^

This token is only valid for fragment shader INPUT declarations.

The Interpolate field specifes the way input is being interpolated by
the rasteriser and is one of TGSI_INTERPOLATE_*.

The Location field specifies the location inside the pixel that the
interpolation should be done at, one of ``TGSI_INTERPOLATE_LOC_*``. Note that
when per-sample shading is enabled, the implementation may choose to
interpolate at the sample irrespective of the Location field.

The CylindricalWrap bitfield specifies which register components
should be subject to cylindrical wrapping when interpolating by the
rasteriser. If TGSI_CYLINDRICAL_WRAP_X is set to 1, the X component
should be interpolated according to cylindrical wrapping rules.


Declaration Sampler View
^^^^^^^^^^^^^^^^^^^^^^^^

Follows Declaration token if file is TGSI_FILE_SAMPLER_VIEW.

DCL SVIEW[#], resource, type(s)

Declares a shader input sampler view and assigns it to a SVIEW[#]
register.

resource can be one of BUFFER, 1D, 2D, 3D, 1DArray and 2DArray.

type must be 1 or 4 entries (if specifying on a per-component
level) out of UNORM, SNORM, SINT, UINT and FLOAT.


Declaration Resource
^^^^^^^^^^^^^^^^^^^^

Follows Declaration token if file is TGSI_FILE_RESOURCE.

DCL RES[#], resource [, WR] [, RAW]

Declares a shader input resource and assigns it to a RES[#]
register.

resource can be one of BUFFER, 1D, 2D, 3D, CUBE, 1DArray and
2DArray.

If the RAW keyword is not specified, the texture data will be
subject to conversion, swizzling and scaling as required to yield
the specified data type from the physical data format of the bound
resource.

If the RAW keyword is specified, no channel conversion will be
performed: the values read for each of the channels (X,Y,Z,W) will
correspond to consecutive words in the same order and format
they're found in memory.  No element-to-address conversion will be
performed either: the value of the provided X coordinate will be
interpreted in byte units instead of texel units.  The result of
accessing a misaligned address is undefined.

Usage of the STORE opcode is only allowed if the WR (writable) flag
is set.


Properties
^^^^^^^^^^^^^^^^^^^^^^^^

Properties are general directives that apply to the whole TGSI program.

FS_COORD_ORIGIN
"""""""""""""""

Specifies the fragment shader TGSI_SEMANTIC_POSITION coordinate origin.
The default value is UPPER_LEFT.

If UPPER_LEFT, the position will be (0,0) at the upper left corner and
increase downward and rightward.
If LOWER_LEFT, the position will be (0,0) at the lower left corner and
increase upward and rightward.

OpenGL defaults to LOWER_LEFT, and is configurable with the
GL_ARB_fragment_coord_conventions extension.

DirectX 9/10 use UPPER_LEFT.

FS_COORD_PIXEL_CENTER
"""""""""""""""""""""

Specifies the fragment shader TGSI_SEMANTIC_POSITION pixel center convention.
The default value is HALF_INTEGER.

If HALF_INTEGER, the fractionary part of the position will be 0.5
If INTEGER, the fractionary part of the position will be 0.0

Note that this does not affect the set of fragments generated by
rasterization, which is instead controlled by half_pixel_center in the
rasterizer.

OpenGL defaults to HALF_INTEGER, and is configurable with the
GL_ARB_fragment_coord_conventions extension.

DirectX 9 uses INTEGER.
DirectX 10 uses HALF_INTEGER.

FS_COLOR0_WRITES_ALL_CBUFS
""""""""""""""""""""""""""
Specifies that writes to the fragment shader color 0 are replicated to all
bound cbufs. This facilitates OpenGL's fragColor output vs fragData[0] where
fragData is directed to a single color buffer, but fragColor is broadcast.

VS_PROHIBIT_UCPS
""""""""""""""""""""""""""
If this property is set on the program bound to the shader stage before the
fragment shader, user clip planes should have no effect (be disabled) even if
that shader does not write to any clip distance outputs and the rasterizer's
clip_plane_enable is non-zero.
This property is only supported by drivers that also support shader clip
distance outputs.
This is useful for APIs that don't have UCPs and where clip distances written
by a shader cannot be disabled.

GS_INVOCATIONS
""""""""""""""

Specifies the number of times a geometry shader should be executed for each
input primitive. Each invocation will have a different
TGSI_SEMANTIC_INVOCATIONID system value set. If not specified, assumed to
be 1.

VS_WINDOW_SPACE_POSITION
""""""""""""""""""""""""""
If this property is set on the vertex shader, the TGSI_SEMANTIC_POSITION output
is assumed to contain window space coordinates.
Division of X,Y,Z by W and the viewport transformation are disabled, and 1/W is
directly taken from the 4-th component of the shader output.
Naturally, clipping is not performed on window coordinates either.
The effect of this property is undefined if a geometry or tessellation shader
are in use.

Texture Sampling and Texture Formats
------------------------------------

This table shows how texture image components are returned as (x,y,z,w) tuples
by TGSI texture instructions, such as :opcode:`TEX`, :opcode:`TXD`, and
:opcode:`TXP`. For reference, OpenGL and Direct3D conventions are shown as
well.

+--------------------+--------------+--------------------+--------------+
| Texture Components | Gallium      | OpenGL             | Direct3D 9   |
+====================+==============+====================+==============+
| R                  | (r, 0, 0, 1) | (r, 0, 0, 1)       | (r, 1, 1, 1) |
+--------------------+--------------+--------------------+--------------+
| RG                 | (r, g, 0, 1) | (r, g, 0, 1)       | (r, g, 1, 1) |
+--------------------+--------------+--------------------+--------------+
| RGB                | (r, g, b, 1) | (r, g, b, 1)       | (r, g, b, 1) |
+--------------------+--------------+--------------------+--------------+
| RGBA               | (r, g, b, a) | (r, g, b, a)       | (r, g, b, a) |
+--------------------+--------------+--------------------+--------------+
| A                  | (0, 0, 0, a) | (0, 0, 0, a)       | (0, 0, 0, a) |
+--------------------+--------------+--------------------+--------------+
| L                  | (l, l, l, 1) | (l, l, l, 1)       | (l, l, l, 1) |
+--------------------+--------------+--------------------+--------------+
| LA                 | (l, l, l, a) | (l, l, l, a)       | (l, l, l, a) |
+--------------------+--------------+--------------------+--------------+
| I                  | (i, i, i, i) | (i, i, i, i)       | N/A          |
+--------------------+--------------+--------------------+--------------+
| UV                 | XXX TBD      | (0, 0, 0, 1)       | (u, v, 1, 1) |
|                    |              | [#envmap-bumpmap]_ |              |
+--------------------+--------------+--------------------+--------------+
| Z                  | XXX TBD      | (z, z, z, 1)       | (0, z, 0, 1) |
|                    |              | [#depth-tex-mode]_ |              |
+--------------------+--------------+--------------------+--------------+
| S                  | (s, s, s, s) | unknown            | unknown      |
+--------------------+--------------+--------------------+--------------+

.. [#envmap-bumpmap] http://www.opengl.org/registry/specs/ATI/envmap_bumpmap.txt
.. [#depth-tex-mode] the default is (z, z, z, 1) but may also be (0, 0, 0, z)
   or (z, z, z, z) depending on the value of GL_DEPTH_TEXTURE_MODE.