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
// basisu_gpu_texture.cpp
// Copyright (C) 2019 Binomial LLC. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//    http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#include "basisu_gpu_texture.h"
#include "basisu_enc.h"
#include "basisu_pvrtc1_4.h"
#include "basisu_astc_decomp.h"

namespace basisu
{
	const int8_t g_etc2_eac_tables[16][8] = 
	{
		{ -3, -6, -9, -15, 2, 5, 8, 14 }, { -3, -7, -10, -13, 2, 6, 9, 12 }, { -2, -5, -8, -13, 1, 4, 7, 12 }, { -2, -4, -6, -13, 1, 3, 5, 12 },
		{ -3, -6, -8, -12, 2, 5, 7, 11 }, { -3, -7, -9, -11, 2, 6, 8, 10 }, { -4, -7, -8, -11, 3, 6, 7, 10 }, { -3, -5, -8, -11, 2, 4, 7, 10 },
		{ -2, -6, -8, -10, 1, 5, 7, 9 }, { -2, -5, -8, -10, 1, 4, 7, 9 }, { -2, -4, -8, -10, 1, 3, 7, 9 }, { -2, -5, -7, -10, 1, 4, 6, 9 },
		{ -3, -4, -7, -10, 2, 3, 6, 9 }, { -1, -2, -3, -10, 0, 1, 2, 9 }, { -4, -6, -8, -9, 3, 5, 7, 8 }, { -3, -5, -7, -9, 2, 4, 6, 8 }
	};

	struct eac_a8_block
	{
		uint16_t m_base : 8;
		uint16_t m_table : 4;
		uint16_t m_multiplier : 4;

		uint8_t m_selectors[6];

		inline uint32_t get_selector(uint32_t x, uint32_t y, uint64_t selector_bits) const
		{
			assert((x < 4) && (y < 4));
			return static_cast<uint32_t>((selector_bits >> (45 - (y + x * 4) * 3)) & 7);
		}
				
		inline uint64_t get_selector_bits() const
		{
			uint64_t pixels = ((uint64_t)m_selectors[0] << 40) | ((uint64_t)m_selectors[1] << 32) | ((uint64_t)m_selectors[2] << 24) |	((uint64_t)m_selectors[3] << 16) | ((uint64_t)m_selectors[4] << 8) | m_selectors[5];
			return pixels;
		}
	};
		
	void unpack_etc2_eac(const void *pBlock_bits, color_rgba *pPixels)
	{
		static_assert(sizeof(eac_a8_block) == 8, "sizeof(eac_a8_block) == 8");

		const eac_a8_block *pBlock = static_cast<const eac_a8_block *>(pBlock_bits);

		const int8_t *pTable = g_etc2_eac_tables[pBlock->m_table];
		
		const uint64_t selector_bits = pBlock->get_selector_bits();
		
		const int32_t base = pBlock->m_base;
		const int32_t mul = pBlock->m_multiplier;

		pPixels[0].a = clamp255(base + pTable[pBlock->get_selector(0, 0, selector_bits)] * mul);
		pPixels[1].a = clamp255(base + pTable[pBlock->get_selector(1, 0, selector_bits)] * mul);
		pPixels[2].a = clamp255(base + pTable[pBlock->get_selector(2, 0, selector_bits)] * mul);
		pPixels[3].a = clamp255(base + pTable[pBlock->get_selector(3, 0, selector_bits)] * mul);

		pPixels[4].a = clamp255(base + pTable[pBlock->get_selector(0, 1, selector_bits)] * mul);
		pPixels[5].a = clamp255(base + pTable[pBlock->get_selector(1, 1, selector_bits)] * mul);
		pPixels[6].a = clamp255(base + pTable[pBlock->get_selector(2, 1, selector_bits)] * mul);
		pPixels[7].a = clamp255(base + pTable[pBlock->get_selector(3, 1, selector_bits)] * mul);

		pPixels[8].a = clamp255(base + pTable[pBlock->get_selector(0, 2, selector_bits)] * mul);
		pPixels[9].a = clamp255(base + pTable[pBlock->get_selector(1, 2, selector_bits)] * mul);
		pPixels[10].a = clamp255(base + pTable[pBlock->get_selector(2, 2, selector_bits)] * mul);
		pPixels[11].a = clamp255(base + pTable[pBlock->get_selector(3, 2, selector_bits)] * mul);

		pPixels[12].a = clamp255(base + pTable[pBlock->get_selector(0, 3, selector_bits)] * mul);
		pPixels[13].a = clamp255(base + pTable[pBlock->get_selector(1, 3, selector_bits)] * mul);
		pPixels[14].a = clamp255(base + pTable[pBlock->get_selector(2, 3, selector_bits)] * mul);
		pPixels[15].a = clamp255(base + pTable[pBlock->get_selector(3, 3, selector_bits)] * mul);
	}

	struct bc1_block
	{
		enum { cTotalEndpointBytes = 2, cTotalSelectorBytes = 4 };

		uint8_t m_low_color[cTotalEndpointBytes];
		uint8_t m_high_color[cTotalEndpointBytes];
		uint8_t m_selectors[cTotalSelectorBytes];
				
		inline uint32_t get_high_color() const	{ return m_high_color[0] | (m_high_color[1] << 8U); }
		inline uint32_t get_low_color() const { return m_low_color[0] | (m_low_color[1] << 8U); }

		static void unpack_color(uint32_t c, uint32_t &r, uint32_t &g, uint32_t &b) 
		{
			r = (c >> 11) & 31;
			g = (c >> 5) & 63;
			b = c & 31;
			
			r = (r << 3) | (r >> 2);
			g = (g << 2) | (g >> 4);
			b = (b << 3) | (b >> 2);
		}

		inline uint32_t get_selector(uint32_t x, uint32_t y) const { assert((x < 4U) && (y < 4U)); return (m_selectors[y] >> (x * 2)) & 3; }
	};

	// Returns true if the block uses 3 color punchthrough alpha mode.
	bool unpack_bc1(const void *pBlock_bits, color_rgba *pPixels, bool set_alpha)
	{
		static_assert(sizeof(bc1_block) == 8, "sizeof(bc1_block) == 8");

		const bc1_block *pBlock = static_cast<const bc1_block *>(pBlock_bits);

		const uint32_t l = pBlock->get_low_color();
		const uint32_t h = pBlock->get_high_color();

		color_rgba c[4];

		uint32_t r0, g0, b0, r1, g1, b1;
		bc1_block::unpack_color(l, r0, g0, b0);
		bc1_block::unpack_color(h, r1, g1, b1);

		bool used_punchthrough = false;

		if (l > h)
		{
			c[0].set_noclamp_rgba(r0, g0, b0, 255);
			c[1].set_noclamp_rgba(r1, g1, b1, 255);
			c[2].set_noclamp_rgba((r0 * 2 + r1) / 3, (g0 * 2 + g1) / 3, (b0 * 2 + b1) / 3, 255);
			c[3].set_noclamp_rgba((r1 * 2 + r0) / 3, (g1 * 2 + g0) / 3, (b1 * 2 + b0) / 3, 255);
		}
		else
		{
			c[0].set_noclamp_rgba(r0, g0, b0, 255);
			c[1].set_noclamp_rgba(r1, g1, b1, 255);
			c[2].set_noclamp_rgba((r0 + r1) / 2, (g0 + g1) / 2, (b0 + b1) / 2, 255);
			c[3].set_noclamp_rgba(0, 0, 0, 0);
			used_punchthrough = true;
		}

		if (set_alpha)
		{
			for (uint32_t y = 0; y < 4; y++, pPixels += 4)
			{
				pPixels[0] = c[pBlock->get_selector(0, y)]; 
				pPixels[1] = c[pBlock->get_selector(1, y)]; 
				pPixels[2] = c[pBlock->get_selector(2, y)]; 
				pPixels[3] = c[pBlock->get_selector(3, y)];
			}
		}
		else
		{
			for (uint32_t y = 0; y < 4; y++, pPixels += 4)
			{
				pPixels[0].set_rgb(c[pBlock->get_selector(0, y)]); 
				pPixels[1].set_rgb(c[pBlock->get_selector(1, y)]); 
				pPixels[2].set_rgb(c[pBlock->get_selector(2, y)]); 
				pPixels[3].set_rgb(c[pBlock->get_selector(3, y)]);
			}
		}

		return used_punchthrough;
	}

	struct bc4_block
	{
		enum { cBC4SelectorBits = 3, cTotalSelectorBytes = 6, cMaxSelectorValues = 8 };
		uint8_t m_endpoints[2];

		uint8_t m_selectors[cTotalSelectorBytes];

		inline uint32_t get_low_alpha() const { return m_endpoints[0]; }
		inline uint32_t get_high_alpha() const { return m_endpoints[1]; }
		inline bool is_alpha6_block() const { return get_low_alpha() <= get_high_alpha(); }

		inline uint64_t get_selector_bits() const
		{ 
			return ((uint64_t)((uint32_t)m_selectors[0] | ((uint32_t)m_selectors[1] << 8U) | ((uint32_t)m_selectors[2] << 16U) | ((uint32_t)m_selectors[3] << 24U))) |
				(((uint64_t)m_selectors[4]) << 32U) |
				(((uint64_t)m_selectors[5]) << 40U);
		}

		inline uint32_t get_selector(uint32_t x, uint32_t y, uint64_t selector_bits) const
		{
			assert((x < 4U) && (y < 4U));
			return (selector_bits >> (((y * 4) + x) * cBC4SelectorBits)) & (cMaxSelectorValues - 1);
		}
				
		static inline uint32_t get_block_values6(uint8_t *pDst, uint32_t l, uint32_t h)
		{
			pDst[0] = static_cast<uint8_t>(l);
			pDst[1] = static_cast<uint8_t>(h);
			pDst[2] = static_cast<uint8_t>((l * 4 + h) / 5);
			pDst[3] = static_cast<uint8_t>((l * 3 + h * 2) / 5);
			pDst[4] = static_cast<uint8_t>((l * 2 + h * 3) / 5);
			pDst[5] = static_cast<uint8_t>((l + h * 4) / 5);
			pDst[6] = 0;
			pDst[7] = 255;
			return 6;
		}

		static inline uint32_t get_block_values8(uint8_t *pDst, uint32_t l, uint32_t h)
		{
			pDst[0] = static_cast<uint8_t>(l);
			pDst[1] = static_cast<uint8_t>(h);
			pDst[2] = static_cast<uint8_t>((l * 6 + h) / 7);
			pDst[3] = static_cast<uint8_t>((l * 5 + h * 2) / 7);
			pDst[4] = static_cast<uint8_t>((l * 4 + h * 3) / 7);
			pDst[5] = static_cast<uint8_t>((l * 3 + h * 4) / 7);
			pDst[6] = static_cast<uint8_t>((l * 2 + h * 5) / 7);
			pDst[7] = static_cast<uint8_t>((l + h * 6) / 7);
			return 8;
		}

		static inline uint32_t get_block_values(uint8_t *pDst, uint32_t l, uint32_t h)
		{
			if (l > h)
				return get_block_values8(pDst, l, h);
			else
				return get_block_values6(pDst, l, h);
		}
	};

	void unpack_bc4(const void *pBlock_bits, uint8_t *pPixels, uint32_t stride)
	{
		static_assert(sizeof(bc4_block) == 8, "sizeof(bc4_block) == 8");

		const bc4_block *pBlock = static_cast<const bc4_block *>(pBlock_bits);

		uint8_t sel_values[8];
		bc4_block::get_block_values(sel_values, pBlock->get_low_alpha(), pBlock->get_high_alpha());

		const uint64_t selector_bits = pBlock->get_selector_bits();

		for (uint32_t y = 0; y < 4; y++, pPixels += (stride * 4U))
		{
			pPixels[0] = sel_values[pBlock->get_selector(0, y, selector_bits)];
			pPixels[stride * 1] = sel_values[pBlock->get_selector(1, y, selector_bits)];
			pPixels[stride * 2] = sel_values[pBlock->get_selector(2, y, selector_bits)];
			pPixels[stride * 3] = sel_values[pBlock->get_selector(3, y, selector_bits)];
		}
	}
	
	// Returns false if the block uses 3-color punchthrough alpha mode, which isn't supported on some GPU's for BC3.
	bool unpack_bc3(const void *pBlock_bits, color_rgba *pPixels)
	{
		bool success = true;

		if (unpack_bc1((const uint8_t *)pBlock_bits + sizeof(bc4_block), pPixels, true))
			success = false;

		unpack_bc4(pBlock_bits, &pPixels[0].a, sizeof(color_rgba));
		
		return success;
	}

	// writes RG
	void unpack_bc5(const void *pBlock_bits, color_rgba *pPixels)
	{
		unpack_bc4(pBlock_bits, &pPixels[0].r, sizeof(color_rgba));
		unpack_bc4((const uint8_t *)pBlock_bits + sizeof(bc4_block), &pPixels[0].g, sizeof(color_rgba));
	}

	// ATC isn't officially documented, so I'm assuming these references:
	// http://www.guildsoftware.com/papers/2012.Converting.DXTC.to.ATC.pdf
	// https://github.com/Triang3l/S3TConv/blob/master/s3tconv_atitc.c
	// The paper incorrectly says the ATC lerp factors are 1/3 and 2/3, but they are actually 3/8 and 5/8.
	void unpack_atc(const void* pBlock_bits, color_rgba* pPixels)
	{
		const uint8_t* pBytes = static_cast<const uint8_t*>(pBlock_bits);

		const uint16_t color0 = pBytes[0] | (pBytes[1] << 8U);
		const uint16_t color1 = pBytes[2] | (pBytes[3] << 8U);
		uint32_t sels = pBytes[4] | (pBytes[5] << 8U) | (pBytes[6] << 16U) | (pBytes[7] << 24U);

		const bool mode = (color0 & 0x8000) != 0;

		color_rgba c[4];

		c[0].set((color0 >> 10) & 31, (color0 >> 5) & 31, color0 & 31, 255);
		c[0].r = (c[0].r << 3) | (c[0].r >> 2);
		c[0].g = (c[0].g << 3) | (c[0].g >> 2);
		c[0].b = (c[0].b << 3) | (c[0].b >> 2);

		c[3].set((color1 >> 11) & 31, (color1 >> 5) & 63, color1 & 31, 255);
		c[3].r = (c[3].r << 3) | (c[3].r >> 2);
		c[3].g = (c[3].g << 2) | (c[3].g >> 4);
		c[3].b = (c[3].b << 3) | (c[3].b >> 2);

		if (mode)
		{
			c[1].set(std::max(0, c[0].r - (c[3].r >> 2)), std::max(0, c[0].g - (c[3].g >> 2)), std::max(0, c[0].b - (c[3].b >> 2)), 255);
			c[2] = c[0];
			c[0].set(0, 0, 0, 255);
		}
		else
		{
			c[1].r = (c[0].r * 5 + c[3].r * 3) >> 3;
			c[1].g = (c[0].g * 5 + c[3].g * 3) >> 3;
			c[1].b = (c[0].b * 5 + c[3].b * 3) >> 3;

			c[2].r = (c[0].r * 3 + c[3].r * 5) >> 3;
			c[2].g = (c[0].g * 3 + c[3].g * 5) >> 3;
			c[2].b = (c[0].b * 3 + c[3].b * 5) >> 3;
		}

		for (uint32_t i = 0; i < 16; i++)
		{
			const uint32_t s = sels & 3;
			
			pPixels[i] = c[s];
							
			sels >>= 2;
		}
	}

	struct bc7_mode_6
	{
		struct
		{
			uint64_t m_mode : 7;
			uint64_t m_r0 : 7;
			uint64_t m_r1 : 7;
			uint64_t m_g0 : 7;
			uint64_t m_g1 : 7;
			uint64_t m_b0 : 7;
			uint64_t m_b1 : 7;
			uint64_t m_a0 : 7;
			uint64_t m_a1 : 7;
			uint64_t m_p0 : 1;
		} m_lo;

		union
		{
			struct
			{
				uint64_t m_p1 : 1;
				uint64_t m_s00 : 3;
				uint64_t m_s10 : 4;
				uint64_t m_s20 : 4;
				uint64_t m_s30 : 4;

				uint64_t m_s01 : 4;
				uint64_t m_s11 : 4;
				uint64_t m_s21 : 4;
				uint64_t m_s31 : 4;

				uint64_t m_s02 : 4;
				uint64_t m_s12 : 4;
				uint64_t m_s22 : 4;
				uint64_t m_s32 : 4;

				uint64_t m_s03 : 4;
				uint64_t m_s13 : 4;
				uint64_t m_s23 : 4;
				uint64_t m_s33 : 4;

			} m_hi;

			uint64_t m_hi_bits;
		};
	};

	static const uint32_t g_bc7_weights4[16] = { 0, 4, 9, 13, 17, 21, 26, 30, 34, 38, 43, 47, 51, 55, 60, 64 };
	
	// The transcoder only outputs mode 6 at the moment, so this is easy.
	bool unpack_bc7_mode6(const void *pBlock_bits, color_rgba *pPixels)
	{
		static_assert(sizeof(bc7_mode_6) == 16, "sizeof(bc7_mode_6) == 16");

		const bc7_mode_6 &block = *static_cast<const bc7_mode_6 *>(pBlock_bits);

		if (block.m_lo.m_mode != (1 << 6))
			return false;

		const uint32_t r0 = (uint32_t)((block.m_lo.m_r0 << 1) | block.m_lo.m_p0);
		const uint32_t g0 = (uint32_t)((block.m_lo.m_g0 << 1) | block.m_lo.m_p0);
		const uint32_t b0 = (uint32_t)((block.m_lo.m_b0 << 1) | block.m_lo.m_p0);
		const uint32_t a0 = (uint32_t)((block.m_lo.m_a0 << 1) | block.m_lo.m_p0);
		const uint32_t r1 = (uint32_t)((block.m_lo.m_r1 << 1) | block.m_hi.m_p1);
		const uint32_t g1 = (uint32_t)((block.m_lo.m_g1 << 1) | block.m_hi.m_p1);
		const uint32_t b1 = (uint32_t)((block.m_lo.m_b1 << 1) | block.m_hi.m_p1);
		const uint32_t a1 = (uint32_t)((block.m_lo.m_a1 << 1) | block.m_hi.m_p1);

		color_rgba vals[16];
		for (uint32_t i = 0; i < 16; i++)
		{
			const uint32_t w = g_bc7_weights4[i];
			const uint32_t iw = 64 - w;
			vals[i].set_noclamp_rgba( 
				(r0 * iw + r1 * w + 32) >> 6, 
				(g0 * iw + g1 * w + 32) >> 6, 
				(b0 * iw + b1 * w + 32) >> 6, 
				(a0 * iw + a1 * w + 32) >> 6);
		}

		pPixels[0] = vals[block.m_hi.m_s00];
		pPixels[1] = vals[block.m_hi.m_s10];
		pPixels[2] = vals[block.m_hi.m_s20];
		pPixels[3] = vals[block.m_hi.m_s30];

		pPixels[4] = vals[block.m_hi.m_s01];
		pPixels[5] = vals[block.m_hi.m_s11];
		pPixels[6] = vals[block.m_hi.m_s21];
		pPixels[7] = vals[block.m_hi.m_s31];
		
		pPixels[8] = vals[block.m_hi.m_s02];
		pPixels[9] = vals[block.m_hi.m_s12];
		pPixels[10] = vals[block.m_hi.m_s22];
		pPixels[11] = vals[block.m_hi.m_s32];

		pPixels[12] = vals[block.m_hi.m_s03];
		pPixels[13] = vals[block.m_hi.m_s13];
		pPixels[14] = vals[block.m_hi.m_s23];
		pPixels[15] = vals[block.m_hi.m_s33];

		return true;
	}

	static inline uint32_t get_block_bits(const uint8_t* pBytes, uint32_t bit_ofs, uint32_t bits_wanted)
	{
		assert(bits_wanted < 32);

		uint32_t v = 0;
		uint32_t total_bits = 0;<--- Shadow variable

		while (total_bits < bits_wanted)
		{
			uint32_t k = pBytes[bit_ofs >> 3];
			k >>= (bit_ofs & 7);
			uint32_t num_bits_in_byte = 8 - (bit_ofs & 7);

			v |= (k << total_bits);
			total_bits += num_bits_in_byte;
			bit_ofs += num_bits_in_byte;
		}

		return v & ((1 << bits_wanted) - 1);
	}
						
	struct bc7_mode_5
	{
		union
		{
			struct
			{
				uint64_t m_mode : 6;
				uint64_t m_rot : 2;
				
				uint64_t m_r0 : 7;
				uint64_t m_r1 : 7;
				uint64_t m_g0 : 7;
				uint64_t m_g1 : 7;
				uint64_t m_b0 : 7;
				uint64_t m_b1 : 7;
				uint64_t m_a0 : 8;
				uint64_t m_a1_0 : 6;

			} m_lo;

			uint64_t m_lo_bits;
		};

		union
		{
			struct
			{
				uint64_t m_a1_1 : 2;

				// bit 2
				uint64_t m_c00 : 1;<--- struct member 'Anonymous9::m_c00' is never used.
				uint64_t m_c10 : 2;<--- struct member 'Anonymous9::m_c10' is never used.
				uint64_t m_c20 : 2;<--- struct member 'Anonymous9::m_c20' is never used.
				uint64_t m_c30 : 2;<--- struct member 'Anonymous9::m_c30' is never used.

				uint64_t m_c01 : 2;<--- struct member 'Anonymous9::m_c01' is never used.
				uint64_t m_c11 : 2;<--- struct member 'Anonymous9::m_c11' is never used.
				uint64_t m_c21 : 2;<--- struct member 'Anonymous9::m_c21' is never used.
				uint64_t m_c31 : 2;<--- struct member 'Anonymous9::m_c31' is never used.

				uint64_t m_c02 : 2;<--- struct member 'Anonymous9::m_c02' is never used.
				uint64_t m_c12 : 2;<--- struct member 'Anonymous9::m_c12' is never used.
				uint64_t m_c22 : 2;<--- struct member 'Anonymous9::m_c22' is never used.
				uint64_t m_c32 : 2;<--- struct member 'Anonymous9::m_c32' is never used.

				uint64_t m_c03 : 2;<--- struct member 'Anonymous9::m_c03' is never used.
				uint64_t m_c13 : 2;<--- struct member 'Anonymous9::m_c13' is never used.
				uint64_t m_c23 : 2;<--- struct member 'Anonymous9::m_c23' is never used.
				uint64_t m_c33 : 2;<--- struct member 'Anonymous9::m_c33' is never used.

				// bit 33
				uint64_t m_a00 : 1;<--- struct member 'Anonymous9::m_a00' is never used.
				uint64_t m_a10 : 2;<--- struct member 'Anonymous9::m_a10' is never used.
				uint64_t m_a20 : 2;<--- struct member 'Anonymous9::m_a20' is never used.
				uint64_t m_a30 : 2;<--- struct member 'Anonymous9::m_a30' is never used.

				uint64_t m_a01 : 2;<--- struct member 'Anonymous9::m_a01' is never used.
				uint64_t m_a11 : 2;<--- struct member 'Anonymous9::m_a11' is never used.
				uint64_t m_a21 : 2;<--- struct member 'Anonymous9::m_a21' is never used.
				uint64_t m_a31 : 2;<--- struct member 'Anonymous9::m_a31' is never used.

				uint64_t m_a02 : 2;<--- struct member 'Anonymous9::m_a02' is never used.
				uint64_t m_a12 : 2;<--- struct member 'Anonymous9::m_a12' is never used.
				uint64_t m_a22 : 2;<--- struct member 'Anonymous9::m_a22' is never used.
				uint64_t m_a32 : 2;<--- struct member 'Anonymous9::m_a32' is never used.

				uint64_t m_a03 : 2;<--- struct member 'Anonymous9::m_a03' is never used.
				uint64_t m_a13 : 2;<--- struct member 'Anonymous9::m_a13' is never used.
				uint64_t m_a23 : 2;<--- struct member 'Anonymous9::m_a23' is never used.
				uint64_t m_a33 : 2;<--- struct member 'Anonymous9::m_a33' is never used.

			} m_hi;

			uint64_t m_hi_bits;
		};

		color_rgba get_low_color() const
		{
			return color_rgba(cNoClamp,
				(int)((m_lo.m_r0 << 1) | (m_lo.m_r0 >> 6)),
				(int)((m_lo.m_g0 << 1) | (m_lo.m_g0 >> 6)),
				(int)((m_lo.m_b0 << 1) | (m_lo.m_b0 >> 6)),
				m_lo.m_a0);
		}

		color_rgba get_high_color() const
		{
			return color_rgba(cNoClamp,
				(int)((m_lo.m_r1 << 1) | (m_lo.m_r1 >> 6)),
				(int)((m_lo.m_g1 << 1) | (m_lo.m_g1 >> 6)),
				(int)((m_lo.m_b1 << 1) | (m_lo.m_b1 >> 6)),
				(int)m_lo.m_a1_0 | ((int)m_hi.m_a1_1 << 6));
		}

		void get_block_colors(color_rgba* pColors) const
		{
			const color_rgba low_color(get_low_color());
			const color_rgba high_color(get_high_color());

			for (uint32_t i = 0; i < 4; i++)
			{
				static const uint32_t s_bc7_weights2[4] = { 0, 21, 43, 64 };

				pColors[i].set_noclamp_rgba(
					(low_color.r * (64 - s_bc7_weights2[i]) + high_color.r * s_bc7_weights2[i] + 32) >> 6,
					(low_color.g * (64 - s_bc7_weights2[i]) + high_color.g * s_bc7_weights2[i] + 32) >> 6,
					(low_color.b * (64 - s_bc7_weights2[i]) + high_color.b * s_bc7_weights2[i] + 32) >> 6,
					(low_color.a * (64 - s_bc7_weights2[i]) + high_color.a * s_bc7_weights2[i] + 32) >> 6);
			}
		} 

		uint32_t get_selector(uint32_t idx, bool alpha) const
		{
			const uint32_t size = (idx == 0) ? 1 : 2;

			uint32_t ofs = alpha ? 97 : 66;
			
			if (idx)
				ofs += 1 + 2 * (idx - 1);

			return get_block_bits(reinterpret_cast<const uint8_t*>(this), ofs, size);
		}
	};

	bool unpack_bc7_mode5(const void* pBlock_bits, color_rgba* pPixels)
	{
		static_assert(sizeof(bc7_mode_5) == 16, "sizeof(bc7_mode_5) == 16");

		const bc7_mode_5& block = *static_cast<const bc7_mode_5*>(pBlock_bits);

		if (block.m_lo.m_mode != (1 << 5))
			return false;
				
		color_rgba block_colors[4];
		block.get_block_colors(block_colors);

		const uint32_t rot = block.m_lo.m_rot;

		for (uint32_t i = 0; i < 16; i++)
		{
			const uint32_t cs = block.get_selector(i, false);

			color_rgba c(block_colors[cs]);

			const uint32_t as = block.get_selector(i, true);
			c.a = block_colors[as].a;

			if (rot > 0)
				std::swap(c[3], c[rot - 1]);

			pPixels[i] = c;
		}

		return true;
	}

	struct fxt1_block
	{
		union
		{
			struct
			{
				uint64_t m_t00 : 2;
				uint64_t m_t01 : 2;<--- struct member 'Anonymous10::m_t01' is never used.
				uint64_t m_t02 : 2;<--- struct member 'Anonymous10::m_t02' is never used.
				uint64_t m_t03 : 2;<--- struct member 'Anonymous10::m_t03' is never used.
				uint64_t m_t04 : 2;<--- struct member 'Anonymous10::m_t04' is never used.
				uint64_t m_t05 : 2;<--- struct member 'Anonymous10::m_t05' is never used.
				uint64_t m_t06 : 2;<--- struct member 'Anonymous10::m_t06' is never used.
				uint64_t m_t07 : 2;<--- struct member 'Anonymous10::m_t07' is never used.
				uint64_t m_t08 : 2;<--- struct member 'Anonymous10::m_t08' is never used.
				uint64_t m_t09 : 2;<--- struct member 'Anonymous10::m_t09' is never used.
				uint64_t m_t10 : 2;<--- struct member 'Anonymous10::m_t10' is never used.
				uint64_t m_t11 : 2;<--- struct member 'Anonymous10::m_t11' is never used.
				uint64_t m_t12 : 2;<--- struct member 'Anonymous10::m_t12' is never used.
				uint64_t m_t13 : 2;<--- struct member 'Anonymous10::m_t13' is never used.
				uint64_t m_t14 : 2;<--- struct member 'Anonymous10::m_t14' is never used.
				uint64_t m_t15 : 2;<--- struct member 'Anonymous10::m_t15' is never used.
				uint64_t m_t16 : 2;
				uint64_t m_t17 : 2;<--- struct member 'Anonymous10::m_t17' is never used.
				uint64_t m_t18 : 2;<--- struct member 'Anonymous10::m_t18' is never used.
				uint64_t m_t19 : 2;<--- struct member 'Anonymous10::m_t19' is never used.
				uint64_t m_t20 : 2;<--- struct member 'Anonymous10::m_t20' is never used.
				uint64_t m_t21 : 2;<--- struct member 'Anonymous10::m_t21' is never used.
				uint64_t m_t22 : 2;<--- struct member 'Anonymous10::m_t22' is never used.
				uint64_t m_t23 : 2;<--- struct member 'Anonymous10::m_t23' is never used.
				uint64_t m_t24 : 2;<--- struct member 'Anonymous10::m_t24' is never used.
				uint64_t m_t25 : 2;<--- struct member 'Anonymous10::m_t25' is never used.
				uint64_t m_t26 : 2;<--- struct member 'Anonymous10::m_t26' is never used.
				uint64_t m_t27 : 2;<--- struct member 'Anonymous10::m_t27' is never used.
				uint64_t m_t28 : 2;<--- struct member 'Anonymous10::m_t28' is never used.
				uint64_t m_t29 : 2;<--- struct member 'Anonymous10::m_t29' is never used.
				uint64_t m_t30 : 2;<--- struct member 'Anonymous10::m_t30' is never used.
				uint64_t m_t31 : 2;<--- struct member 'Anonymous10::m_t31' is never used.
			} m_lo;
			uint64_t m_lo_bits;
			uint8_t m_sels[8];
		};

		union
		{
			struct
			{
#ifdef BASISU_USE_ORIGINAL_3DFX_FXT1_ENCODING
				// This is the format that 3DFX's DECOMP.EXE tool expects, which I'm assuming is what the actual 3DFX hardware wanted.
				// Unfortunately, color0/color1 and color2/color3 are flipped relative to the official OpenGL extension and Intel's documentation!
				uint64_t m_b1 : 5;
				uint64_t m_g1 : 5;
				uint64_t m_r1 : 5;
				uint64_t m_b0 : 5;
				uint64_t m_g0 : 5;
				uint64_t m_r0 : 5;
				uint64_t m_b3 : 5;
				uint64_t m_g3 : 5;
				uint64_t m_r3 : 5;
				uint64_t m_b2 : 5;
				uint64_t m_g2 : 5;
				uint64_t m_r2 : 5;
#else
				// Intel's encoding, and the encoding in the OpenGL FXT1 spec.
				uint64_t m_b0 : 5;
				uint64_t m_g0 : 5;
				uint64_t m_r0 : 5;
				uint64_t m_b1 : 5;
				uint64_t m_g1 : 5;
				uint64_t m_r1 : 5;
				uint64_t m_b2 : 5;
				uint64_t m_g2 : 5;
				uint64_t m_r2 : 5;
				uint64_t m_b3 : 5;
				uint64_t m_g3 : 5;
				uint64_t m_r3 : 5;
#endif
				uint64_t m_alpha : 1;
				uint64_t m_glsb : 2;
				uint64_t m_mode : 1;
			} m_hi;

			uint64_t m_hi_bits;
		};
	};

	static color_rgba expand_565(const color_rgba& c)
	{
		return color_rgba((c.r << 3) | (c.r >> 2), (c.g << 2) | (c.g >> 4), (c.b << 3) | (c.b >> 2), 255);
	}

	// We only support CC_MIXED non-alpha blocks here because that's the only mode the transcoder uses at the moment.
	bool unpack_fxt1(const void *p, color_rgba *pPixels)
	{
		const fxt1_block* pBlock = static_cast<const fxt1_block*>(p);

		if (pBlock->m_hi.m_mode == 0)
			return false;
		if (pBlock->m_hi.m_alpha == 1)
			return false;
				
		color_rgba colors[4];

		colors[0].r = pBlock->m_hi.m_r0;
		colors[0].g = (uint8_t)((pBlock->m_hi.m_g0 << 1) | ((pBlock->m_lo.m_t00 >> 1) ^ (pBlock->m_hi.m_glsb & 1)));
		colors[0].b = pBlock->m_hi.m_b0;
		colors[0].a = 255;

		colors[1].r = pBlock->m_hi.m_r1;
		colors[1].g = (uint8_t)((pBlock->m_hi.m_g1 << 1) | (pBlock->m_hi.m_glsb & 1));
		colors[1].b = pBlock->m_hi.m_b1;
		colors[1].a = 255;

		colors[2].r = pBlock->m_hi.m_r2;
		colors[2].g = (uint8_t)((pBlock->m_hi.m_g2 << 1) | ((pBlock->m_lo.m_t16 >> 1) ^ (pBlock->m_hi.m_glsb >> 1)));
		colors[2].b = pBlock->m_hi.m_b2;
		colors[2].a = 255;

		colors[3].r = pBlock->m_hi.m_r3;
		colors[3].g = (uint8_t)((pBlock->m_hi.m_g3 << 1) | (pBlock->m_hi.m_glsb >> 1));
		colors[3].b = pBlock->m_hi.m_b3;
		colors[3].a = 255;

		for (uint32_t i = 0; i < 4; i++)
			colors[i] = expand_565(colors[i]);

		color_rgba block0_colors[4];
		block0_colors[0] = colors[0];
		block0_colors[1] = color_rgba((colors[0].r * 2 + colors[1].r + 1) / 3, (colors[0].g * 2 + colors[1].g + 1) / 3, (colors[0].b * 2 + colors[1].b + 1) / 3, 255);
		block0_colors[2] = color_rgba((colors[1].r * 2 + colors[0].r + 1) / 3, (colors[1].g * 2 + colors[0].g + 1) / 3, (colors[1].b * 2 + colors[0].b + 1) / 3, 255);
		block0_colors[3] = colors[1];

		for (uint32_t i = 0; i < 16; i++)
		{
			const uint32_t sel = (pBlock->m_sels[i >> 2] >> ((i & 3) * 2)) & 3;

			const uint32_t x = i & 3;
			const uint32_t y = i >> 2;
			pPixels[x + y * 8] = block0_colors[sel];
		}

		color_rgba block1_colors[4];
		block1_colors[0] = colors[2];
		block1_colors[1] = color_rgba((colors[2].r * 2 + colors[3].r + 1) / 3, (colors[2].g * 2 + colors[3].g + 1) / 3, (colors[2].b * 2 + colors[3].b + 1) / 3, 255);
		block1_colors[2] = color_rgba((colors[3].r * 2 + colors[2].r + 1) / 3, (colors[3].g * 2 + colors[2].g + 1) / 3, (colors[3].b * 2 + colors[2].b + 1) / 3, 255);
		block1_colors[3] = colors[3];

		for (uint32_t i = 0; i < 16; i++)
		{
			const uint32_t sel = (pBlock->m_sels[4 + (i >> 2)] >> ((i & 3) * 2)) & 3;
			
			const uint32_t x = i & 3;
			const uint32_t y = i >> 2;
			pPixels[4 + x + y * 8] = block1_colors[sel];
		}

		return true;
	}

	struct pvrtc2_block
	{
		uint8_t m_modulation[4];

		union
		{
			union
			{
				// Opaque mode: RGB colora=554 and colorb=555
				struct
				{
					uint32_t m_mod_flag : 1;
					uint32_t m_blue_a : 4;
					uint32_t m_green_a : 5;
					uint32_t m_red_a : 5;
					uint32_t m_hard_flag : 1;
					uint32_t m_blue_b : 5;
					uint32_t m_green_b : 5;
					uint32_t m_red_b : 5;
					uint32_t m_opaque_flag : 1;

				} m_opaque_color_data;

				// Transparent mode: RGBA colora=4433 and colorb=4443
				struct
				{
					uint32_t m_mod_flag : 1;
					uint32_t m_blue_a : 3;
					uint32_t m_green_a : 4;
					uint32_t m_red_a : 4;
					uint32_t m_alpha_a : 3;
					uint32_t m_hard_flag : 1;
					uint32_t m_blue_b : 4;
					uint32_t m_green_b : 4;
					uint32_t m_red_b : 4;
					uint32_t m_alpha_b : 3;
					uint32_t m_opaque_flag : 1;

				} m_trans_color_data;
			};

			uint32_t m_color_data_bits;
		};
	};

	static color_rgba convert_rgb_555_to_888(const color_rgba& col)
	{
		return color_rgba((col[0] << 3) | (col[0] >> 2), (col[1] << 3) | (col[1] >> 2), (col[2] << 3) | (col[2] >> 2), 255);
	}
	
	static color_rgba convert_rgba_5554_to_8888(const color_rgba& col)
	{
		return color_rgba((col[0] << 3) | (col[0] >> 2), (col[1] << 3) | (col[1] >> 2), (col[2] << 3) | (col[2] >> 2), (col[3] << 4) | col[3]);
	}

	// PVRTC2 is currently limited to only what our transcoder outputs (non-interpolated, hard_flag=1 modulation=0). In this mode, PVRTC2 looks much like BC1/ATC.
	bool unpack_pvrtc2(const void *p, color_rgba *pPixels)
	{
		const pvrtc2_block* pBlock = static_cast<const pvrtc2_block*>(p);

		if ((!pBlock->m_opaque_color_data.m_hard_flag) || (pBlock->m_opaque_color_data.m_mod_flag))
		{
			// This mode isn't supported by the transcoder, so we aren't bothering with it here.
			return false;
		}

		color_rgba colors[4];

		if (pBlock->m_opaque_color_data.m_opaque_flag)
		{
			// colora=554
			color_rgba color_a(pBlock->m_opaque_color_data.m_red_a, pBlock->m_opaque_color_data.m_green_a, (pBlock->m_opaque_color_data.m_blue_a << 1) | (pBlock->m_opaque_color_data.m_blue_a >> 3), 255);
			
			// colora=555
			color_rgba color_b(pBlock->m_opaque_color_data.m_red_b, pBlock->m_opaque_color_data.m_green_b, pBlock->m_opaque_color_data.m_blue_b, 255);
						
			colors[0] = convert_rgb_555_to_888(color_a);
			colors[3] = convert_rgb_555_to_888(color_b);

			colors[1].set((colors[0].r * 5 + colors[3].r * 3) / 8, (colors[0].g * 5 + colors[3].g * 3) / 8, (colors[0].b * 5 + colors[3].b * 3) / 8, 255);
			colors[2].set((colors[0].r * 3 + colors[3].r * 5) / 8, (colors[0].g * 3 + colors[3].g * 5) / 8, (colors[0].b * 3 + colors[3].b * 5) / 8, 255);
		}
		else
		{
			// colora=4433 
			color_rgba color_a(
				(pBlock->m_trans_color_data.m_red_a << 1) | (pBlock->m_trans_color_data.m_red_a >> 3), 
				(pBlock->m_trans_color_data.m_green_a << 1) | (pBlock->m_trans_color_data.m_green_a >> 3),
				(pBlock->m_trans_color_data.m_blue_a << 2) | (pBlock->m_trans_color_data.m_blue_a >> 1), 
				pBlock->m_trans_color_data.m_alpha_a << 1);

			//colorb=4443
			color_rgba color_b(
				(pBlock->m_trans_color_data.m_red_b << 1) | (pBlock->m_trans_color_data.m_red_b >> 3),
				(pBlock->m_trans_color_data.m_green_b << 1) | (pBlock->m_trans_color_data.m_green_b >> 3),
				(pBlock->m_trans_color_data.m_blue_b << 1) | (pBlock->m_trans_color_data.m_blue_b >> 3),
				(pBlock->m_trans_color_data.m_alpha_b << 1) | 1);

			colors[0] = convert_rgba_5554_to_8888(color_a);
			colors[3] = convert_rgba_5554_to_8888(color_b);
		}

		colors[1].set((colors[0].r * 5 + colors[3].r * 3) / 8, (colors[0].g * 5 + colors[3].g * 3) / 8, (colors[0].b * 5 + colors[3].b * 3) / 8, (colors[0].a * 5 + colors[3].a * 3) / 8);
		colors[2].set((colors[0].r * 3 + colors[3].r * 5) / 8, (colors[0].g * 3 + colors[3].g * 5) / 8, (colors[0].b * 3 + colors[3].b * 5) / 8, (colors[0].a * 3 + colors[3].a * 5) / 8);

		for (uint32_t i = 0; i < 16; i++)
		{
			const uint32_t sel = (pBlock->m_modulation[i >> 2] >> ((i & 3) * 2)) & 3;
			pPixels[i] = colors[sel];
		}

		return true;
	}

	struct etc2_eac_r11
	{
		uint64_t m_base	: 8;
		uint64_t m_table	: 4;
		uint64_t m_mul		: 4;
		uint64_t m_sels_0 : 8;
		uint64_t m_sels_1 : 8;
		uint64_t m_sels_2 : 8;
		uint64_t m_sels_3 : 8;
		uint64_t m_sels_4 : 8;
		uint64_t m_sels_5 : 8;

		uint64_t get_sels() const
		{
			return ((uint64_t)m_sels_0 << 40U) | ((uint64_t)m_sels_1 << 32U) | ((uint64_t)m_sels_2 << 24U) | ((uint64_t)m_sels_3 << 16U) | ((uint64_t)m_sels_4 << 8U) | m_sels_5;
		}

		void set_sels(uint64_t v)
		{
			m_sels_0 = (v >> 40U) & 0xFF;
			m_sels_1 = (v >> 32U) & 0xFF;
			m_sels_2 = (v >> 24U) & 0xFF;
			m_sels_3 = (v >> 16U) & 0xFF;
			m_sels_4 = (v >> 8U) & 0xFF;
			m_sels_5 = v & 0xFF;
		}
	};

	struct etc2_eac_rg11
	{
		etc2_eac_r11 m_c[2];
	};

	static void unpack_etc2_eac_r(const etc2_eac_r11* p, color_rgba* pPixels, uint32_t c)
	{
		const uint64_t sels = p->get_sels();

		const int base = (int)p->m_base * 8 + 4;
		const int mul = p->m_mul ? ((int)p->m_mul * 8) : 1;
		const int table = (int)p->m_table;

		for (uint32_t y = 0; y < 4; y++)
		{
			for (uint32_t x = 0; x < 4; x++)
			{
				const uint32_t shift = 45 - ((y + x * 4) * 3);
				
				const uint32_t sel = (uint32_t)((sels >> shift) & 7);
				
				int val = base + g_etc2_eac_tables[table][sel] * mul;
				val = clamp<int>(val, 0, 2047);

				// Convert to 8-bits with rounding
				pPixels[x + y * 4].m_comps[c] = static_cast<uint8_t>((val * 255 + 1024) / 2047);

			} // x
		} // y
	}

	void unpack_etc2_eac_rg(const void* p, color_rgba* pPixels)
	{
		for (uint32_t c = 0; c < 2; c++)
		{
			const etc2_eac_r11* pBlock = &static_cast<const etc2_eac_rg11*>(p)->m_c[c];

			unpack_etc2_eac_r(pBlock, pPixels, c);
		}
	}
	
	// Unpacks to RGBA, R, RG, or A
	bool unpack_block(texture_format fmt, const void* pBlock, color_rgba* pPixels)
	{
		switch (fmt)
		{
		case texture_format::cBC1:
		{
			unpack_bc1(pBlock, pPixels, true);
			break;
		}
		case texture_format::cBC3:
		{
			return unpack_bc3(pBlock, pPixels);
		}
		case texture_format::cBC4:
		{
			// Unpack to R
			unpack_bc4(pBlock, &pPixels[0].r, sizeof(color_rgba));
			break;
		}
		case texture_format::cBC5:
		{
			unpack_bc5(pBlock, pPixels);
			break;
		}
		case texture_format::cBC7:
		{
			// We only support modes 5 and 6.
			if (!unpack_bc7_mode5(pBlock, pPixels))
			{
				if (!unpack_bc7_mode6(pBlock, pPixels))
					return false;
			}

			break;
		}
		// Full ETC2 color blocks (planar/T/H modes) is currently unsupported in basisu, but we do support ETC2 with alpha (using ETC1 for color)
		case texture_format::cETC2_RGB:
		case texture_format::cETC1:
		case texture_format::cETC1S:
		{
			return unpack_etc1(*static_cast<const etc_block*>(pBlock), pPixels);
		}
		case texture_format::cETC2_RGBA:
		{
			if (!unpack_etc1(static_cast<const etc_block*>(pBlock)[1], pPixels))
				return false;
			unpack_etc2_eac(pBlock, pPixels);
			break;
		}
		case texture_format::cETC2_ALPHA:
		{
			// Unpack to A
			unpack_etc2_eac(pBlock, pPixels);
			break;
		}
		case texture_format::cASTC4x4:
		{
			const bool astc_srgb = false;
			basisu_astc::astc::decompress(reinterpret_cast<uint8_t*>(pPixels), static_cast<const uint8_t*>(pBlock), astc_srgb, 4, 4);
			break;
		}
		case texture_format::cATC_RGB:
		{
			unpack_atc(pBlock, pPixels);
			break;
		}
		case texture_format::cATC_RGBA_INTERPOLATED_ALPHA:
		{
			unpack_atc(static_cast<const uint8_t*>(pBlock) + 8, pPixels);
			unpack_bc4(pBlock, &pPixels[0].a, sizeof(color_rgba));
			break;
		}
		case texture_format::cFXT1_RGB:
		{
			unpack_fxt1(pBlock, pPixels);
			break;
		}
		case texture_format::cPVRTC2_4_RGBA:
		{
			unpack_pvrtc2(pBlock, pPixels);
			break;
		}
		case texture_format::cETC2_R11_EAC:
		{
			unpack_etc2_eac_r(static_cast<const etc2_eac_r11 *>(pBlock), pPixels, 0);
			break;
		}
		case texture_format::cETC2_RG11_EAC:
		{
			unpack_etc2_eac_rg(pBlock, pPixels);
			break;
		}
		default:
		{
			assert(0);
			// TODO
			return false;
		}
		}
		return true;
	}

	bool gpu_image::unpack(image& img) const
	{
		img.resize(get_pixel_width(), get_pixel_height());
		img.set_all(g_black_color);

		if (!img.get_width() || !img.get_height())
			return true;

		if ((m_fmt == texture_format::cPVRTC1_4_RGB) || (m_fmt == texture_format::cPVRTC1_4_RGBA))
		{
			pvrtc4_image pi(m_width, m_height);
			
			if (get_total_blocks() != pi.get_total_blocks())
				return false;
			
			memcpy(&pi.get_blocks()[0], get_ptr(), get_size_in_bytes());

			pi.deswizzle();

			pi.unpack_all_pixels(img);

			return true;
		}

		assert((m_block_width <= cMaxBlockSize) && (m_block_height <= cMaxBlockSize));
		color_rgba pixels[cMaxBlockSize * cMaxBlockSize];
		for (uint32_t i = 0; i < cMaxBlockSize * cMaxBlockSize; i++)
			pixels[i] = g_black_color;

		bool success = true;

		for (uint32_t by = 0; by < m_blocks_y; by++)
		{
			for (uint32_t bx = 0; bx < m_blocks_x; bx++)
			{
				const void* pBlock = get_block_ptr(bx, by);

				if (!unpack_block(m_fmt, pBlock, pixels))
					success = false;

				img.set_block_clipped(pixels, bx * m_block_width, by * m_block_height, m_block_width, m_block_height);
			} // bx
		} // by

		return success;
	}
		
	static const uint8_t g_ktx_file_id[12] = { 0xAB, 0x4B, 0x54, 0x58, 0x20, 0x31, 0x31, 0xBB, 0x0D, 0x0A, 0x1A, 0x0A };

	// KTX/GL enums
	enum
	{
		KTX_ENDIAN = 0x04030201, 
		KTX_OPPOSITE_ENDIAN = 0x01020304,
		KTX_ETC1_RGB8_OES = 0x8D64,
		KTX_RED = 0x1903,
		KTX_RG = 0x8227,
		KTX_RGB = 0x1907,
		KTX_RGBA = 0x1908,
		KTX_COMPRESSED_RGB_S3TC_DXT1_EXT = 0x83F0,
		KTX_COMPRESSED_RGBA_S3TC_DXT5_EXT = 0x83F3,
		KTX_COMPRESSED_RED_RGTC1_EXT = 0x8DBB,
		KTX_COMPRESSED_RED_GREEN_RGTC2_EXT = 0x8DBD,
		KTX_COMPRESSED_RGB8_ETC2 = 0x9274,
		KTX_COMPRESSED_RGBA8_ETC2_EAC = 0x9278,
		KTX_COMPRESSED_RGBA_BPTC_UNORM = 0x8E8C,
		KTX_COMPRESSED_SRGB_ALPHA_BPTC_UNORM = 0x8E8D,
		KTX_COMPRESSED_RGB_PVRTC_4BPPV1_IMG = 0x8C00,
		KTX_COMPRESSED_RGBA_PVRTC_4BPPV1_IMG = 0x8C02,
		KTX_COMPRESSED_RGBA_ASTC_4x4_KHR = 0x93B0,
		KTX_COMPRESSED_SRGB8_ALPHA8_ASTC_4x4_KHR = 0x93D0,
		KTX_ATC_RGB_AMD = 0x8C92,
		KTX_ATC_RGBA_INTERPOLATED_ALPHA_AMD = 0x87EE,
		KTX_COMPRESSED_RGB_FXT1_3DFX = 0x86B0,
		KTX_COMPRESSED_RGBA_FXT1_3DFX = 0x86B1,
		KTX_COMPRESSED_RGBA_PVRTC_4BPPV2_IMG = 0x9138,
		KTX_COMPRESSED_R11_EAC = 0x9270,
		KTX_COMPRESSED_RG11_EAC = 0x9272
	};
		
	struct ktx_header
	{
		uint8_t m_identifier[12];
		packed_uint<4> m_endianness;
		packed_uint<4> m_glType;
		packed_uint<4> m_glTypeSize;
		packed_uint<4> m_glFormat;
		packed_uint<4> m_glInternalFormat;
		packed_uint<4> m_glBaseInternalFormat;
		packed_uint<4> m_pixelWidth;
		packed_uint<4> m_pixelHeight;
		packed_uint<4> m_pixelDepth;
		packed_uint<4> m_numberOfArrayElements;
		packed_uint<4> m_numberOfFaces;
		packed_uint<4> m_numberOfMipmapLevels;
		packed_uint<4> m_bytesOfKeyValueData;

		void clear() { clear_obj(*this);	}
	};

	// Input is a texture array of mipmapped gpu_image's: gpu_images[array_index][level_index]
	bool create_ktx_texture_file(uint8_vec &ktx_data, const std::vector<gpu_image_vec>& gpu_images, bool cubemap_flag)
	{
		if (!gpu_images.size())
		{
			assert(0);
			return false;
		}

		uint32_t width = 0, height = 0, total_levels = 0;
		basisu::texture_format fmt = texture_format::cInvalidTextureFormat;

		if (cubemap_flag)
		{
			if ((gpu_images.size() % 6) != 0)
			{
				assert(0);
				return false;
			}
		}

		for (uint32_t array_index = 0; array_index < gpu_images.size(); array_index++)
		{
			const gpu_image_vec &levels = gpu_images[array_index];

			if (!levels.size())
			{
				// Empty mip chain
				assert(0);
				return false;
			}

			if (!array_index)
			{
				width = levels[0].get_pixel_width();
				height = levels[0].get_pixel_height();
				total_levels = (uint32_t)levels.size();
				fmt = levels[0].get_format();
			}
			else
			{
				if ((width != levels[0].get_pixel_width()) ||
				    (height != levels[0].get_pixel_height()) ||
				    (total_levels != levels.size()))
				{
					// All cubemap/texture array faces must be the same dimension
					assert(0);
					return false;
				}
			}

			for (uint32_t level_index = 0; level_index < levels.size(); level_index++)
			{
				if (level_index)
				{
					if ( (levels[level_index].get_pixel_width() != maximum<uint32_t>(1, levels[0].get_pixel_width() >> level_index)) ||
							(levels[level_index].get_pixel_height() != maximum<uint32_t>(1, levels[0].get_pixel_height() >> level_index)) )
					{
						// Malformed mipmap chain
						assert(0);
						return false;
					}
				}

				if (fmt != levels[level_index].get_format())
				{
					// All input textures must use the same GPU format
					assert(0);
					return false;
				}
			}
		}

		uint32_t internal_fmt = KTX_ETC1_RGB8_OES, base_internal_fmt = KTX_RGB;

		switch (fmt)
		{
		case texture_format::cBC1:
		{
			internal_fmt = KTX_COMPRESSED_RGB_S3TC_DXT1_EXT;
			break;
		}
		case texture_format::cBC3:
		{
			internal_fmt = KTX_COMPRESSED_RGBA_S3TC_DXT5_EXT;
			base_internal_fmt = KTX_RGBA;
			break;
		}
		case texture_format::cBC4:
		{
			internal_fmt = KTX_COMPRESSED_RED_RGTC1_EXT;// KTX_COMPRESSED_LUMINANCE_LATC1_EXT;
			base_internal_fmt = KTX_RED;
			break;
		}
		case texture_format::cBC5:
		{
			internal_fmt = KTX_COMPRESSED_RED_GREEN_RGTC2_EXT;
			base_internal_fmt = KTX_RG;
			break;
		}
		case texture_format::cETC1:
		case texture_format::cETC1S:
		{
			internal_fmt = KTX_ETC1_RGB8_OES;
			break;
		}
		case texture_format::cETC2_RGB:
		{
			internal_fmt = KTX_COMPRESSED_RGB8_ETC2;
			break;
		}
		case texture_format::cETC2_RGBA:
		{
			internal_fmt = KTX_COMPRESSED_RGBA8_ETC2_EAC;
			base_internal_fmt = KTX_RGBA;
			break;
		}
		case texture_format::cBC7:
		{
			internal_fmt = KTX_COMPRESSED_RGBA_BPTC_UNORM;
			base_internal_fmt = KTX_RGBA;
			break;
		}
		case texture_format::cPVRTC1_4_RGB:
		{
			internal_fmt = KTX_COMPRESSED_RGB_PVRTC_4BPPV1_IMG;
			break;
		}
		case texture_format::cPVRTC1_4_RGBA:
		{
			internal_fmt = KTX_COMPRESSED_RGBA_PVRTC_4BPPV1_IMG;
			base_internal_fmt = KTX_RGBA;
			break;
		}
		case texture_format::cASTC4x4:
		{
			internal_fmt = KTX_COMPRESSED_RGBA_ASTC_4x4_KHR;
			base_internal_fmt = KTX_RGBA;
			break;
		}
		case texture_format::cATC_RGB:
		{
			internal_fmt = KTX_ATC_RGB_AMD;
			break;
		}
		case texture_format::cATC_RGBA_INTERPOLATED_ALPHA:
		{
			internal_fmt = KTX_ATC_RGBA_INTERPOLATED_ALPHA_AMD;
			base_internal_fmt = KTX_RGBA;
			break;
		}
		case texture_format::cETC2_R11_EAC:
		{
			internal_fmt = KTX_COMPRESSED_R11_EAC;
			base_internal_fmt = KTX_RED;
			break;
		}
		case texture_format::cETC2_RG11_EAC:
		{
			internal_fmt = KTX_COMPRESSED_RG11_EAC;
			base_internal_fmt = KTX_RG;
			break;
		}
		case texture_format::cFXT1_RGB:
		{
			internal_fmt = KTX_COMPRESSED_RGB_FXT1_3DFX;
			break;
		}
		case texture_format::cPVRTC2_4_RGBA:
		{
			internal_fmt = KTX_COMPRESSED_RGBA_PVRTC_4BPPV2_IMG;
			base_internal_fmt = KTX_RGBA;
			break;
		}
		default:
		{
			// TODO
			assert(0);
			return false;
		}
		}
		
		ktx_header header;
		header.clear();
		memcpy(&header.m_identifier, g_ktx_file_id, sizeof(g_ktx_file_id));
		header.m_endianness = KTX_ENDIAN;
		
		header.m_pixelWidth = width;
		header.m_pixelHeight = height;
		
		header.m_glInternalFormat = internal_fmt;
		header.m_glBaseInternalFormat = base_internal_fmt;

		header.m_numberOfArrayElements = (uint32_t)(cubemap_flag ? (gpu_images.size() / 6) : gpu_images.size());
		if (header.m_numberOfArrayElements == 1)
			header.m_numberOfArrayElements = 0;

		header.m_numberOfMipmapLevels = total_levels;
		header.m_numberOfFaces = cubemap_flag ? 6 : 1;

		append_vector(ktx_data, (uint8_t *)&header, sizeof(header));

		for (uint32_t level_index = 0; level_index < total_levels; level_index++)
		{
			uint32_t img_size = gpu_images[0][level_index].get_size_in_bytes();
			
			if ((header.m_numberOfFaces == 1) || (header.m_numberOfArrayElements > 1))
			{
				img_size = img_size * header.m_numberOfFaces * maximum<uint32_t>(1, header.m_numberOfArrayElements);
			}

			assert(img_size && ((img_size & 3) == 0));

			packed_uint<4> packed_img_size(img_size);
			append_vector(ktx_data, (uint8_t *)&packed_img_size, sizeof(packed_img_size));

			uint32_t bytes_written = 0;

			for (uint32_t array_index = 0; array_index < maximum<uint32_t>(1, header.m_numberOfArrayElements); array_index++)
			{
				for (uint32_t face_index = 0; face_index < header.m_numberOfFaces; face_index++)
				{
					const gpu_image& img = gpu_images[cubemap_flag ? (array_index * 6 + face_index) : array_index][level_index];

					append_vector(ktx_data, (uint8_t *)img.get_ptr(), img.get_size_in_bytes());
					
					bytes_written += img.get_size_in_bytes();
				}
			
			} // array_index

		} // level_index

		return true;
	}

	bool write_compressed_texture_file(const char* pFilename, const std::vector<gpu_image_vec>& g, bool cubemap_flag)
	{
		std::string extension(string_tolower(string_get_extension(pFilename)));

		uint8_vec filedata;
		if (extension == "ktx")
		{
			if (!create_ktx_texture_file(filedata, g, cubemap_flag))
				return false;
		}
		else if (extension == "pvr")
		{
			// TODO
			return false;
		}
		else if (extension == "dds")
		{
			// TODO
			return false;
		}
		else
		{
			// unsupported texture format
			assert(0);
			return false;
		}

		return basisu::write_vec_to_file(pFilename, filedata);
	}

	bool write_compressed_texture_file(const char* pFilename, const gpu_image& g)
	{
		std::vector<gpu_image_vec> v;
		enlarge_vector(v, 1)->push_back(g);
		return write_compressed_texture_file(pFilename, v, false);
	}

	const uint32_t OUT_FILE_MAGIC = 'TEXC';
	struct out_file_header 
	{
		packed_uint<4> m_magic;
		packed_uint<4> m_pad;
		packed_uint<4> m_width;
		packed_uint<4> m_height;
	};

	// As no modern tool supports FXT1 format .KTX files, let's write .OUT files and make sure 3DFX's original tools shipped in 1999 can decode our encoded output.
	bool write_3dfx_out_file(const char* pFilename, const gpu_image& gi)
	{
		out_file_header hdr;
		hdr.m_magic = OUT_FILE_MAGIC;
		hdr.m_pad = 0;
		hdr.m_width = gi.get_blocks_x() * 8;
		hdr.m_height = gi.get_blocks_y() * 4;

		FILE* pFile = nullptr;
#ifdef _WIN32
		fopen_s(&pFile, pFilename, "wb");
#else
		pFile = fopen(pFilename, "wb");
#endif
		if (!pFile)
			return false;

		fwrite(&hdr, sizeof(hdr), 1, pFile);
		fwrite(gi.get_ptr(), gi.get_size_in_bytes(), 1, pFile);
		
		return fclose(pFile) != EOF;
	}
} // basisu