summaryrefslogblamecommitdiffstats
path: root/src/video_core/textures/astc.cpp
blob: b2adbe888f90c2d075520765eb7808774f76b346 (plain) (tree)
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


























                                                                           



                                                                               




                                



























































                                                           
                          

                             

                       
 
                      























































































































































































































































































                                                                                                   






                                  


















































































































































































































































































                                                                                        


                                         

       



                                                                                                 


























































































































































































































































































































































































































































































































































































































































































































































































































































































































































































                                                                                                    
// Copyright 2016 The University of North Carolina at Chapel Hill
//
// 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.
//
// Please send all BUG REPORTS to <pavel@cs.unc.edu>.
// <http://gamma.cs.unc.edu/FasTC/>

#include <algorithm>
#include <cassert>
#include <cstdint>
#include <cstring>
#include <vector>

#include "video_core/textures/astc.h"

class BitStream {
public:
    explicit BitStream(unsigned char* ptr, int nBits = 0, int start_offset = 0)
        : m_NumBits(nBits), m_CurByte(ptr), m_NextBit(start_offset % 8) {}

    ~BitStream() = default;

    int GetBitsWritten() const {
        return m_BitsWritten;
    }

    void WriteBitsR(unsigned int val, unsigned int nBits) {
        for (unsigned int i = 0; i < nBits; i++) {
            WriteBit((val >> (nBits - i - 1)) & 1);
        }
    }

    void WriteBits(unsigned int val, unsigned int nBits) {
        for (unsigned int i = 0; i < nBits; i++) {
            WriteBit((val >> i) & 1);
        }
    }

    int GetBitsRead() const {
        return m_BitsRead;
    }

    int ReadBit() {

        int bit = *m_CurByte >> m_NextBit++;
        while (m_NextBit >= 8) {
            m_NextBit -= 8;
            m_CurByte++;
        }

        m_BitsRead++;
        return bit & 1;
    }

    unsigned int ReadBits(unsigned int nBits) {
        unsigned int ret = 0;
        for (unsigned int i = 0; i < nBits; i++) {
            ret |= (ReadBit() & 1) << i;
        }
        return ret;
    }

private:
    void WriteBit(int b) {

        if (done)
            return;

        const unsigned int mask = 1 << m_NextBit++;

        // clear the bit
        *m_CurByte &= ~mask;

        // Write the bit, if necessary
        if (b)
            *m_CurByte |= mask;

        // Next byte?
        if (m_NextBit >= 8) {
            m_CurByte += 1;
            m_NextBit = 0;
        }

        done = done || ++m_BitsWritten >= m_NumBits;
    }

    int m_BitsWritten = 0;
    const int m_NumBits;
    unsigned char* m_CurByte;
    int m_NextBit = 0;
    int m_BitsRead = 0;

    bool done = false;
};

template <typename IntType>
class Bits {
private:
    const IntType& m_Bits;

    // Don't copy
    Bits() {}
    Bits(const Bits&) {}
    Bits& operator=(const Bits&) {}

public:
    explicit Bits(IntType& v) : m_Bits(v) {}

    uint8_t operator[](uint32_t bitPos) {
        return static_cast<uint8_t>((m_Bits >> bitPos) & 1);
    }

    IntType operator()(uint32_t start, uint32_t end) {
        if (start == end) {
            return (*this)[start];
        } else if (start > end) {
            uint32_t t = start;
            start = end;
            end = t;
        }

        uint64_t mask = (1 << (end - start + 1)) - 1;
        return (m_Bits >> start) & mask;
    }
};

enum EIntegerEncoding { eIntegerEncoding_JustBits, eIntegerEncoding_Quint, eIntegerEncoding_Trit };

class IntegerEncodedValue {
private:
    const EIntegerEncoding m_Encoding;
    const uint32_t m_NumBits;
    uint32_t m_BitValue;
    union {
        uint32_t m_QuintValue;
        uint32_t m_TritValue;
    };

public:
    // Jank, but we're not doing any heavy lifting in this class, so it's
    // probably OK. It allows us to use these in std::vectors...
    IntegerEncodedValue& operator=(const IntegerEncodedValue& other) {
        new (this) IntegerEncodedValue(other);
        return *this;
    }

    IntegerEncodedValue(EIntegerEncoding encoding, uint32_t numBits)
        : m_Encoding(encoding), m_NumBits(numBits) {}

    EIntegerEncoding GetEncoding() const {
        return m_Encoding;
    }
    uint32_t BaseBitLength() const {
        return m_NumBits;
    }

    uint32_t GetBitValue() const {
        return m_BitValue;
    }
    void SetBitValue(uint32_t val) {
        m_BitValue = val;
    }

    uint32_t GetTritValue() const {
        return m_TritValue;
    }
    void SetTritValue(uint32_t val) {
        m_TritValue = val;
    }

    uint32_t GetQuintValue() const {
        return m_QuintValue;
    }
    void SetQuintValue(uint32_t val) {
        m_QuintValue = val;
    }

    bool MatchesEncoding(const IntegerEncodedValue& other) {
        return m_Encoding == other.m_Encoding && m_NumBits == other.m_NumBits;
    }

    // Returns the number of bits required to encode nVals values.
    uint32_t GetBitLength(uint32_t nVals) {
        uint32_t totalBits = m_NumBits * nVals;
        if (m_Encoding == eIntegerEncoding_Trit) {
            totalBits += (nVals * 8 + 4) / 5;
        } else if (m_Encoding == eIntegerEncoding_Quint) {
            totalBits += (nVals * 7 + 2) / 3;
        }
        return totalBits;
    }

    // Count the number of bits set in a number.
    static inline uint32_t Popcnt(uint32_t n) {
        uint32_t c;
        for (c = 0; n; c++) {
            n &= n - 1;
        }
        return c;
    }

    // Returns a new instance of this struct that corresponds to the
    // can take no more than maxval values
    static IntegerEncodedValue CreateEncoding(uint32_t maxVal) {
        while (maxVal > 0) {
            uint32_t check = maxVal + 1;

            // Is maxVal a power of two?
            if (!(check & (check - 1))) {
                return IntegerEncodedValue(eIntegerEncoding_JustBits, Popcnt(maxVal));
            }

            // Is maxVal of the type 3*2^n - 1?
            if ((check % 3 == 0) && !((check / 3) & ((check / 3) - 1))) {
                return IntegerEncodedValue(eIntegerEncoding_Trit, Popcnt(check / 3 - 1));
            }

            // Is maxVal of the type 5*2^n - 1?
            if ((check % 5 == 0) && !((check / 5) & ((check / 5) - 1))) {
                return IntegerEncodedValue(eIntegerEncoding_Quint, Popcnt(check / 5 - 1));
            }

            // Apparently it can't be represented with a bounded integer sequence...
            // just iterate.
            maxVal--;
        }
        return IntegerEncodedValue(eIntegerEncoding_JustBits, 0);
    }

    // Fills result with the values that are encoded in the given
    // bitstream. We must know beforehand what the maximum possible
    // value is, and how many values we're decoding.
    static void DecodeIntegerSequence(std::vector<IntegerEncodedValue>& result, BitStream& bits,
                                      uint32_t maxRange, uint32_t nValues) {
        // Determine encoding parameters
        IntegerEncodedValue val = IntegerEncodedValue::CreateEncoding(maxRange);

        // Start decoding
        uint32_t nValsDecoded = 0;
        while (nValsDecoded < nValues) {
            switch (val.GetEncoding()) {
            case eIntegerEncoding_Quint:
                DecodeQuintBlock(bits, result, val.BaseBitLength());
                nValsDecoded += 3;
                break;

            case eIntegerEncoding_Trit:
                DecodeTritBlock(bits, result, val.BaseBitLength());
                nValsDecoded += 5;
                break;

            case eIntegerEncoding_JustBits:
                val.SetBitValue(bits.ReadBits(val.BaseBitLength()));
                result.push_back(val);
                nValsDecoded++;
                break;
            }
        }
    }

private:
    static void DecodeTritBlock(BitStream& bits, std::vector<IntegerEncodedValue>& result,
                                uint32_t nBitsPerValue) {
        // Implement the algorithm in section C.2.12
        uint32_t m[5];
        uint32_t t[5];
        uint32_t T;

        // Read the trit encoded block according to
        // table C.2.14
        m[0] = bits.ReadBits(nBitsPerValue);
        T = bits.ReadBits(2);
        m[1] = bits.ReadBits(nBitsPerValue);
        T |= bits.ReadBits(2) << 2;
        m[2] = bits.ReadBits(nBitsPerValue);
        T |= bits.ReadBit() << 4;
        m[3] = bits.ReadBits(nBitsPerValue);
        T |= bits.ReadBits(2) << 5;
        m[4] = bits.ReadBits(nBitsPerValue);
        T |= bits.ReadBit() << 7;

        uint32_t C = 0;

        Bits<uint32_t> Tb(T);
        if (Tb(2, 4) == 7) {
            C = (Tb(5, 7) << 2) | Tb(0, 1);
            t[4] = t[3] = 2;
        } else {
            C = Tb(0, 4);
            if (Tb(5, 6) == 3) {
                t[4] = 2;
                t[3] = Tb[7];
            } else {
                t[4] = Tb[7];
                t[3] = Tb(5, 6);
            }
        }

        Bits<uint32_t> Cb(C);
        if (Cb(0, 1) == 3) {
            t[2] = 2;
            t[1] = Cb[4];
            t[0] = (Cb[3] << 1) | (Cb[2] & ~Cb[3]);
        } else if (Cb(2, 3) == 3) {
            t[2] = 2;
            t[1] = 2;
            t[0] = Cb(0, 1);
        } else {
            t[2] = Cb[4];
            t[1] = Cb(2, 3);
            t[0] = (Cb[1] << 1) | (Cb[0] & ~Cb[1]);
        }

        for (uint32_t i = 0; i < 5; i++) {
            IntegerEncodedValue val(eIntegerEncoding_Trit, nBitsPerValue);
            val.SetBitValue(m[i]);
            val.SetTritValue(t[i]);
            result.push_back(val);
        }
    }

    static void DecodeQuintBlock(BitStream& bits, std::vector<IntegerEncodedValue>& result,
                                 uint32_t nBitsPerValue) {
        // Implement the algorithm in section C.2.12
        uint32_t m[3];
        uint32_t q[3];
        uint32_t Q;

        // Read the trit encoded block according to
        // table C.2.15
        m[0] = bits.ReadBits(nBitsPerValue);
        Q = bits.ReadBits(3);
        m[1] = bits.ReadBits(nBitsPerValue);
        Q |= bits.ReadBits(2) << 3;
        m[2] = bits.ReadBits(nBitsPerValue);
        Q |= bits.ReadBits(2) << 5;

        Bits<uint32_t> Qb(Q);
        if (Qb(1, 2) == 3 && Qb(5, 6) == 0) {
            q[0] = q[1] = 4;
            q[2] = (Qb[0] << 2) | ((Qb[4] & ~Qb[0]) << 1) | (Qb[3] & ~Qb[0]);
        } else {
            uint32_t C = 0;
            if (Qb(1, 2) == 3) {
                q[2] = 4;
                C = (Qb(3, 4) << 3) | ((~Qb(5, 6) & 3) << 1) | Qb[0];
            } else {
                q[2] = Qb(5, 6);
                C = Qb(0, 4);
            }

            Bits<uint32_t> Cb(C);
            if (Cb(0, 2) == 5) {
                q[1] = 4;
                q[0] = Cb(3, 4);
            } else {
                q[1] = Cb(3, 4);
                q[0] = Cb(0, 2);
            }
        }

        for (uint32_t i = 0; i < 3; i++) {
            IntegerEncodedValue val(eIntegerEncoding_Quint, nBitsPerValue);
            val.m_BitValue = m[i];
            val.m_QuintValue = q[i];
            result.push_back(val);
        }
    }
};

namespace ASTCC {

struct TexelWeightParams {
    uint32_t m_Width = 0;
    uint32_t m_Height = 0;
    bool m_bDualPlane = false;
    uint32_t m_MaxWeight = 0;
    bool m_bError = false;
    bool m_bVoidExtentLDR = false;
    bool m_bVoidExtentHDR = false;

    uint32_t GetPackedBitSize() {
        // How many indices do we have?
        uint32_t nIdxs = m_Height * m_Width;
        if (m_bDualPlane) {
            nIdxs *= 2;
        }

        return IntegerEncodedValue::CreateEncoding(m_MaxWeight).GetBitLength(nIdxs);
    }

    uint32_t GetNumWeightValues() const {
        uint32_t ret = m_Width * m_Height;
        if (m_bDualPlane) {
            ret *= 2;
        }
        return ret;
    }
};

TexelWeightParams DecodeBlockInfo(BitStream& strm) {
    TexelWeightParams params;

    // Read the entire block mode all at once
    uint16_t modeBits = strm.ReadBits(11);

    // Does this match the void extent block mode?
    if ((modeBits & 0x01FF) == 0x1FC) {
        if (modeBits & 0x200) {
            params.m_bVoidExtentHDR = true;
        } else {
            params.m_bVoidExtentLDR = true;
        }

        // Next two bits must be one.
        if (!(modeBits & 0x400) || !strm.ReadBit()) {
            params.m_bError = true;
        }

        return params;
    }

    // First check if the last four bits are zero
    if ((modeBits & 0xF) == 0) {
        params.m_bError = true;
        return params;
    }

    // If the last two bits are zero, then if bits
    // [6-8] are all ones, this is also reserved.
    if ((modeBits & 0x3) == 0 && (modeBits & 0x1C0) == 0x1C0) {
        params.m_bError = true;
        return params;
    }

    // Otherwise, there is no error... Figure out the layout
    // of the block mode. Layout is determined by a number
    // between 0 and 9 corresponding to table C.2.8 of the
    // ASTC spec.
    uint32_t layout = 0;

    if ((modeBits & 0x1) || (modeBits & 0x2)) {
        // layout is in [0-4]
        if (modeBits & 0x8) {
            // layout is in [2-4]
            if (modeBits & 0x4) {
                // layout is in [3-4]
                if (modeBits & 0x100) {
                    layout = 4;
                } else {
                    layout = 3;
                }
            } else {
                layout = 2;
            }
        } else {
            // layout is in [0-1]
            if (modeBits & 0x4) {
                layout = 1;
            } else {
                layout = 0;
            }
        }
    } else {
        // layout is in [5-9]
        if (modeBits & 0x100) {
            // layout is in [7-9]
            if (modeBits & 0x80) {
                // layout is in [7-8]
                assert((modeBits & 0x40) == 0U);
                if (modeBits & 0x20) {
                    layout = 8;
                } else {
                    layout = 7;
                }
            } else {
                layout = 9;
            }
        } else {
            // layout is in [5-6]
            if (modeBits & 0x80) {
                layout = 6;
            } else {
                layout = 5;
            }
        }
    }

    assert(layout < 10);

    // Determine R
    uint32_t R = !!(modeBits & 0x10);
    if (layout < 5) {
        R |= (modeBits & 0x3) << 1;
    } else {
        R |= (modeBits & 0xC) >> 1;
    }
    assert(2 <= R && R <= 7);

    // Determine width & height
    switch (layout) {
    case 0: {
        uint32_t A = (modeBits >> 5) & 0x3;
        uint32_t B = (modeBits >> 7) & 0x3;
        params.m_Width = B + 4;
        params.m_Height = A + 2;
        break;
    }

    case 1: {
        uint32_t A = (modeBits >> 5) & 0x3;
        uint32_t B = (modeBits >> 7) & 0x3;
        params.m_Width = B + 8;
        params.m_Height = A + 2;
        break;
    }

    case 2: {
        uint32_t A = (modeBits >> 5) & 0x3;
        uint32_t B = (modeBits >> 7) & 0x3;
        params.m_Width = A + 2;
        params.m_Height = B + 8;
        break;
    }

    case 3: {
        uint32_t A = (modeBits >> 5) & 0x3;
        uint32_t B = (modeBits >> 7) & 0x1;
        params.m_Width = A + 2;
        params.m_Height = B + 6;
        break;
    }

    case 4: {
        uint32_t A = (modeBits >> 5) & 0x3;
        uint32_t B = (modeBits >> 7) & 0x1;
        params.m_Width = B + 2;
        params.m_Height = A + 2;
        break;
    }

    case 5: {
        uint32_t A = (modeBits >> 5) & 0x3;
        params.m_Width = 12;
        params.m_Height = A + 2;
        break;
    }

    case 6: {
        uint32_t A = (modeBits >> 5) & 0x3;
        params.m_Width = A + 2;
        params.m_Height = 12;
        break;
    }

    case 7: {
        params.m_Width = 6;
        params.m_Height = 10;
        break;
    }

    case 8: {
        params.m_Width = 10;
        params.m_Height = 6;
        break;
    }

    case 9: {
        uint32_t A = (modeBits >> 5) & 0x3;
        uint32_t B = (modeBits >> 9) & 0x3;
        params.m_Width = A + 6;
        params.m_Height = B + 6;
        break;
    }

    default:
        assert(!"Don't know this layout...");
        params.m_bError = true;
        break;
    }

    // Determine whether or not we're using dual planes
    // and/or high precision layouts.
    bool D = (layout != 9) && (modeBits & 0x400);
    bool H = (layout != 9) && (modeBits & 0x200);

    if (H) {
        const uint32_t maxWeights[6] = {9, 11, 15, 19, 23, 31};
        params.m_MaxWeight = maxWeights[R - 2];
    } else {
        const uint32_t maxWeights[6] = {1, 2, 3, 4, 5, 7};
        params.m_MaxWeight = maxWeights[R - 2];
    }

    params.m_bDualPlane = D;

    return params;
}

void FillVoidExtentLDR(BitStream& strm, uint32_t* const outBuf, uint32_t blockWidth,
                       uint32_t blockHeight) {
    // Don't actually care about the void extent, just read the bits...
    for (int i = 0; i < 4; ++i) {
        strm.ReadBits(13);
    }

    // Decode the RGBA components and renormalize them to the range [0, 255]
    uint16_t r = strm.ReadBits(16);
    uint16_t g = strm.ReadBits(16);
    uint16_t b = strm.ReadBits(16);
    uint16_t a = strm.ReadBits(16);

    uint32_t rgba = (r >> 8) | (g & 0xFF00) | (static_cast<uint32_t>(b) & 0xFF00) << 8 |
                    (static_cast<uint32_t>(a) & 0xFF00) << 16;

    for (uint32_t j = 0; j < blockHeight; j++)
        for (uint32_t i = 0; i < blockWidth; i++) {
            outBuf[j * blockWidth + i] = rgba;
        }
}

void FillError(uint32_t* outBuf, uint32_t blockWidth, uint32_t blockHeight) {
    for (uint32_t j = 0; j < blockHeight; j++)
        for (uint32_t i = 0; i < blockWidth; i++) {
            outBuf[j * blockWidth + i] = 0xFFFF00FF;
        }
}

// Replicates low numBits such that [(toBit - 1):(toBit - 1 - fromBit)]
// is the same as [(numBits - 1):0] and repeats all the way down.
template <typename IntType>
IntType Replicate(const IntType& val, uint32_t numBits, uint32_t toBit) {
    if (numBits == 0)
        return 0;
    if (toBit == 0)
        return 0;
    IntType v = val & ((1 << numBits) - 1);
    IntType res = v;
    uint32_t reslen = numBits;
    while (reslen < toBit) {
        uint32_t comp = 0;
        if (numBits > toBit - reslen) {
            uint32_t newshift = toBit - reslen;
            comp = numBits - newshift;
            numBits = newshift;
        }
        res <<= numBits;
        res |= v >> comp;
        reslen += numBits;
    }
    return res;
}

class Pixel {
protected:
    using ChannelType = int16_t;
    uint8_t m_BitDepth[4] = {8, 8, 8, 8};
    int16_t color[4] = {};

public:
    Pixel() = default;
    Pixel(ChannelType a, ChannelType r, ChannelType g, ChannelType b, unsigned bitDepth = 8)
        : m_BitDepth{uint8_t(bitDepth), uint8_t(bitDepth), uint8_t(bitDepth), uint8_t(bitDepth)},
          color{a, r, g, b} {}

    // Changes the depth of each pixel. This scales the values to
    // the appropriate bit depth by either truncating the least
    // significant bits when going from larger to smaller bit depth
    // or by repeating the most significant bits when going from
    // smaller to larger bit depths.
    void ChangeBitDepth(const uint8_t (&depth)[4]) {
        for (uint32_t i = 0; i < 4; i++) {
            Component(i) = ChangeBitDepth(Component(i), m_BitDepth[i], depth[i]);
            m_BitDepth[i] = depth[i];
        }
    }

    template <typename IntType>
    static float ConvertChannelToFloat(IntType channel, uint8_t bitDepth) {
        float denominator = static_cast<float>((1 << bitDepth) - 1);
        return static_cast<float>(channel) / denominator;
    }

    // Changes the bit depth of a single component. See the comment
    // above for how we do this.
    static ChannelType ChangeBitDepth(Pixel::ChannelType val, uint8_t oldDepth, uint8_t newDepth) {
        assert(newDepth <= 8);
        assert(oldDepth <= 8);

        if (oldDepth == newDepth) {
            // Do nothing
            return val;
        } else if (oldDepth == 0 && newDepth != 0) {
            return (1 << newDepth) - 1;
        } else if (newDepth > oldDepth) {
            return Replicate(val, oldDepth, newDepth);
        } else {
            // oldDepth > newDepth
            if (newDepth == 0) {
                return 0xFF;
            } else {
                uint8_t bitsWasted = oldDepth - newDepth;
                uint16_t v = static_cast<uint16_t>(val);
                v = (v + (1 << (bitsWasted - 1))) >> bitsWasted;
                v = ::std::min<uint16_t>(::std::max<uint16_t>(0, v), (1 << newDepth) - 1);
                return static_cast<uint8_t>(v);
            }
        }

        assert(!"We shouldn't get here.");
        return 0;
    }

    const ChannelType& A() const {
        return color[0];
    }
    ChannelType& A() {
        return color[0];
    }
    const ChannelType& R() const {
        return color[1];
    }
    ChannelType& R() {
        return color[1];
    }
    const ChannelType& G() const {
        return color[2];
    }
    ChannelType& G() {
        return color[2];
    }
    const ChannelType& B() const {
        return color[3];
    }
    ChannelType& B() {
        return color[3];
    }
    const ChannelType& Component(uint32_t idx) const {
        return color[idx];
    }
    ChannelType& Component(uint32_t idx) {
        return color[idx];
    }

    void GetBitDepth(uint8_t (&outDepth)[4]) const {
        for (int i = 0; i < 4; i++) {
            outDepth[i] = m_BitDepth[i];
        }
    }

    // Take all of the components, transform them to their 8-bit variants,
    // and then pack each channel into an R8G8B8A8 32-bit integer. We assume
    // that the architecture is little-endian, so the alpha channel will end
    // up in the most-significant byte.
    uint32_t Pack() const {
        Pixel eightBit(*this);
        const uint8_t eightBitDepth[4] = {8, 8, 8, 8};
        eightBit.ChangeBitDepth(eightBitDepth);

        uint32_t r = 0;
        r |= eightBit.A();
        r <<= 8;
        r |= eightBit.B();
        r <<= 8;
        r |= eightBit.G();
        r <<= 8;
        r |= eightBit.R();
        return r;
    }

    // Clamps the pixel to the range [0,255]
    void ClampByte() {
        for (uint32_t i = 0; i < 4; i++) {
            color[i] = (color[i] < 0) ? 0 : ((color[i] > 255) ? 255 : color[i]);
        }
    }

    void MakeOpaque() {
        A() = 255;
    }
};

void DecodeColorValues(uint32_t* out, uint8_t* data, uint32_t* modes, const uint32_t nPartitions,
                       const uint32_t nBitsForColorData) {
    // First figure out how many color values we have
    uint32_t nValues = 0;
    for (uint32_t i = 0; i < nPartitions; i++) {
        nValues += ((modes[i] >> 2) + 1) << 1;
    }

    // Then based on the number of values and the remaining number of bits,
    // figure out the max value for each of them...
    uint32_t range = 256;
    while (--range > 0) {
        IntegerEncodedValue val = IntegerEncodedValue::CreateEncoding(range);
        uint32_t bitLength = val.GetBitLength(nValues);
        if (bitLength <= nBitsForColorData) {
            // Find the smallest possible range that matches the given encoding
            while (--range > 0) {
                IntegerEncodedValue newval = IntegerEncodedValue::CreateEncoding(range);
                if (!newval.MatchesEncoding(val)) {
                    break;
                }
            }

            // Return to last matching range.
            range++;
            break;
        }
    }

    // We now have enough to decode our integer sequence.
    std::vector<IntegerEncodedValue> decodedColorValues;
    BitStream colorStream(data);
    IntegerEncodedValue::DecodeIntegerSequence(decodedColorValues, colorStream, range, nValues);

    // Once we have the decoded values, we need to dequantize them to the 0-255 range
    // This procedure is outlined in ASTC spec C.2.13
    uint32_t outIdx = 0;
    std::vector<IntegerEncodedValue>::const_iterator itr;
    for (itr = decodedColorValues.begin(); itr != decodedColorValues.end(); itr++) {
        // Have we already decoded all that we need?
        if (outIdx >= nValues) {
            break;
        }

        const IntegerEncodedValue& val = *itr;
        uint32_t bitlen = val.BaseBitLength();
        uint32_t bitval = val.GetBitValue();

        assert(bitlen >= 1);

        uint32_t A = 0, B = 0, C = 0, D = 0;
        // A is just the lsb replicated 9 times.
        A = Replicate(bitval & 1, 1, 9);

        switch (val.GetEncoding()) {
        // Replicate bits
        case eIntegerEncoding_JustBits:
            out[outIdx++] = Replicate(bitval, bitlen, 8);
            break;

        // Use algorithm in C.2.13
        case eIntegerEncoding_Trit: {

            D = val.GetTritValue();

            switch (bitlen) {
            case 1: {
                C = 204;
            } break;

            case 2: {
                C = 93;
                // B = b000b0bb0
                uint32_t b = (bitval >> 1) & 1;
                B = (b << 8) | (b << 4) | (b << 2) | (b << 1);
            } break;

            case 3: {
                C = 44;
                // B = cb000cbcb
                uint32_t cb = (bitval >> 1) & 3;
                B = (cb << 7) | (cb << 2) | cb;
            } break;

            case 4: {
                C = 22;
                // B = dcb000dcb
                uint32_t dcb = (bitval >> 1) & 7;
                B = (dcb << 6) | dcb;
            } break;

            case 5: {
                C = 11;
                // B = edcb000ed
                uint32_t edcb = (bitval >> 1) & 0xF;
                B = (edcb << 5) | (edcb >> 2);
            } break;

            case 6: {
                C = 5;
                // B = fedcb000f
                uint32_t fedcb = (bitval >> 1) & 0x1F;
                B = (fedcb << 4) | (fedcb >> 4);
            } break;

            default:
                assert(!"Unsupported trit encoding for color values!");
                break;
            } // switch(bitlen)
        }     // case eIntegerEncoding_Trit
        break;

        case eIntegerEncoding_Quint: {

            D = val.GetQuintValue();

            switch (bitlen) {
            case 1: {
                C = 113;
            } break;

            case 2: {
                C = 54;
                // B = b0000bb00
                uint32_t b = (bitval >> 1) & 1;
                B = (b << 8) | (b << 3) | (b << 2);
            } break;

            case 3: {
                C = 26;
                // B = cb0000cbc
                uint32_t cb = (bitval >> 1) & 3;
                B = (cb << 7) | (cb << 1) | (cb >> 1);
            } break;

            case 4: {
                C = 13;
                // B = dcb0000dc
                uint32_t dcb = (bitval >> 1) & 7;
                B = (dcb << 6) | (dcb >> 1);
            } break;

            case 5: {
                C = 6;
                // B = edcb0000e
                uint32_t edcb = (bitval >> 1) & 0xF;
                B = (edcb << 5) | (edcb >> 3);
            } break;

            default:
                assert(!"Unsupported quint encoding for color values!");
                break;
            } // switch(bitlen)
        }     // case eIntegerEncoding_Quint
        break;
        } // switch(val.GetEncoding())

        if (val.GetEncoding() != eIntegerEncoding_JustBits) {
            uint32_t T = D * C + B;
            T ^= A;
            T = (A & 0x80) | (T >> 2);
            out[outIdx++] = T;
        }
    }

    // Make sure that each of our values is in the proper range...
    for (uint32_t i = 0; i < nValues; i++) {
        assert(out[i] <= 255);
    }
}

uint32_t UnquantizeTexelWeight(const IntegerEncodedValue& val) {
    uint32_t bitval = val.GetBitValue();
    uint32_t bitlen = val.BaseBitLength();

    uint32_t A = Replicate(bitval & 1, 1, 7);
    uint32_t B = 0, C = 0, D = 0;

    uint32_t result = 0;
    switch (val.GetEncoding()) {
    case eIntegerEncoding_JustBits:
        result = Replicate(bitval, bitlen, 6);
        break;

    case eIntegerEncoding_Trit: {
        D = val.GetTritValue();
        assert(D < 3);

        switch (bitlen) {
        case 0: {
            uint32_t results[3] = {0, 32, 63};
            result = results[D];
        } break;

        case 1: {
            C = 50;
        } break;

        case 2: {
            C = 23;
            uint32_t b = (bitval >> 1) & 1;
            B = (b << 6) | (b << 2) | b;
        } break;

        case 3: {
            C = 11;
            uint32_t cb = (bitval >> 1) & 3;
            B = (cb << 5) | cb;
        } break;

        default:
            assert(!"Invalid trit encoding for texel weight");
            break;
        }
    } break;

    case eIntegerEncoding_Quint: {
        D = val.GetQuintValue();
        assert(D < 5);

        switch (bitlen) {
        case 0: {
            uint32_t results[5] = {0, 16, 32, 47, 63};
            result = results[D];
        } break;

        case 1: {
            C = 28;
        } break;

        case 2: {
            C = 13;
            uint32_t b = (bitval >> 1) & 1;
            B = (b << 6) | (b << 1);
        } break;

        default:
            assert(!"Invalid quint encoding for texel weight");
            break;
        }
    } break;
    }

    if (val.GetEncoding() != eIntegerEncoding_JustBits && bitlen > 0) {
        // Decode the value...
        result = D * C + B;
        result ^= A;
        result = (A & 0x20) | (result >> 2);
    }

    assert(result < 64);

    // Change from [0,63] to [0,64]
    if (result > 32) {
        result += 1;
    }

    return result;
}

void UnquantizeTexelWeights(uint32_t out[2][144], std::vector<IntegerEncodedValue>& weights,
                            const TexelWeightParams& params, const uint32_t blockWidth,
                            const uint32_t blockHeight) {
    uint32_t weightIdx = 0;
    uint32_t unquantized[2][144];
    std::vector<IntegerEncodedValue>::const_iterator itr;
    for (itr = weights.begin(); itr != weights.end(); itr++) {
        unquantized[0][weightIdx] = UnquantizeTexelWeight(*itr);

        if (params.m_bDualPlane) {
            itr++;
            unquantized[1][weightIdx] = UnquantizeTexelWeight(*itr);
            if (itr == weights.end()) {
                break;
            }
        }

        if (++weightIdx >= (params.m_Width * params.m_Height))
            break;
    }

    // Do infill if necessary (Section C.2.18) ...
    uint32_t Ds = (1024 + (blockWidth / 2)) / (blockWidth - 1);
    uint32_t Dt = (1024 + (blockHeight / 2)) / (blockHeight - 1);

    const uint32_t kPlaneScale = params.m_bDualPlane ? 2U : 1U;
    for (uint32_t plane = 0; plane < kPlaneScale; plane++)
        for (uint32_t t = 0; t < blockHeight; t++)
            for (uint32_t s = 0; s < blockWidth; s++) {
                uint32_t cs = Ds * s;
                uint32_t ct = Dt * t;

                uint32_t gs = (cs * (params.m_Width - 1) + 32) >> 6;
                uint32_t gt = (ct * (params.m_Height - 1) + 32) >> 6;

                uint32_t js = gs >> 4;
                uint32_t fs = gs & 0xF;

                uint32_t jt = gt >> 4;
                uint32_t ft = gt & 0x0F;

                uint32_t w11 = (fs * ft + 8) >> 4;
                uint32_t w10 = ft - w11;
                uint32_t w01 = fs - w11;
                uint32_t w00 = 16 - fs - ft + w11;

                uint32_t v0 = js + jt * params.m_Width;

#define FIND_TEXEL(tidx, bidx)                                                                     \
    uint32_t p##bidx = 0;                                                                          \
    do {                                                                                           \
        if ((tidx) < (params.m_Width * params.m_Height)) {                                         \
            p##bidx = unquantized[plane][(tidx)];                                                  \
        }                                                                                          \
    } while (0)

                FIND_TEXEL(v0, 00);
                FIND_TEXEL(v0 + 1, 01);
                FIND_TEXEL(v0 + params.m_Width, 10);
                FIND_TEXEL(v0 + params.m_Width + 1, 11);

#undef FIND_TEXEL

                out[plane][t * blockWidth + s] =
                    (p00 * w00 + p01 * w01 + p10 * w10 + p11 * w11 + 8) >> 4;
            }
}

// Transfers a bit as described in C.2.14
static inline void BitTransferSigned(int32_t& a, int32_t& b) {
    b >>= 1;
    b |= a & 0x80;
    a >>= 1;
    a &= 0x3F;
    if (a & 0x20)
        a -= 0x40;
}

// Adds more precision to the blue channel as described
// in C.2.14
static inline Pixel BlueContract(int32_t a, int32_t r, int32_t g, int32_t b) {
    return Pixel(static_cast<int16_t>(a), static_cast<int16_t>((r + b) >> 1),
                 static_cast<int16_t>((g + b) >> 1), static_cast<int16_t>(b));
}

// Partition selection functions as specified in
// C.2.21
static inline uint32_t hash52(uint32_t p) {
    p ^= p >> 15;
    p -= p << 17;
    p += p << 7;
    p += p << 4;
    p ^= p >> 5;
    p += p << 16;
    p ^= p >> 7;
    p ^= p >> 3;
    p ^= p << 6;
    p ^= p >> 17;
    return p;
}

static uint32_t SelectPartition(int32_t seed, int32_t x, int32_t y, int32_t z,
                                int32_t partitionCount, int32_t smallBlock) {
    if (1 == partitionCount)
        return 0;

    if (smallBlock) {
        x <<= 1;
        y <<= 1;
        z <<= 1;
    }

    seed += (partitionCount - 1) * 1024;

    uint32_t rnum = hash52(static_cast<uint32_t>(seed));
    uint8_t seed1 = static_cast<uint8_t>(rnum & 0xF);
    uint8_t seed2 = static_cast<uint8_t>((rnum >> 4) & 0xF);
    uint8_t seed3 = static_cast<uint8_t>((rnum >> 8) & 0xF);
    uint8_t seed4 = static_cast<uint8_t>((rnum >> 12) & 0xF);
    uint8_t seed5 = static_cast<uint8_t>((rnum >> 16) & 0xF);
    uint8_t seed6 = static_cast<uint8_t>((rnum >> 20) & 0xF);
    uint8_t seed7 = static_cast<uint8_t>((rnum >> 24) & 0xF);
    uint8_t seed8 = static_cast<uint8_t>((rnum >> 28) & 0xF);
    uint8_t seed9 = static_cast<uint8_t>((rnum >> 18) & 0xF);
    uint8_t seed10 = static_cast<uint8_t>((rnum >> 22) & 0xF);
    uint8_t seed11 = static_cast<uint8_t>((rnum >> 26) & 0xF);
    uint8_t seed12 = static_cast<uint8_t>(((rnum >> 30) | (rnum << 2)) & 0xF);

    seed1 *= seed1;
    seed2 *= seed2;
    seed3 *= seed3;
    seed4 *= seed4;
    seed5 *= seed5;
    seed6 *= seed6;
    seed7 *= seed7;
    seed8 *= seed8;
    seed9 *= seed9;
    seed10 *= seed10;
    seed11 *= seed11;
    seed12 *= seed12;

    int32_t sh1, sh2, sh3;
    if (seed & 1) {
        sh1 = (seed & 2) ? 4 : 5;
        sh2 = (partitionCount == 3) ? 6 : 5;
    } else {
        sh1 = (partitionCount == 3) ? 6 : 5;
        sh2 = (seed & 2) ? 4 : 5;
    }
    sh3 = (seed & 0x10) ? sh1 : sh2;

    seed1 >>= sh1;
    seed2 >>= sh2;
    seed3 >>= sh1;
    seed4 >>= sh2;
    seed5 >>= sh1;
    seed6 >>= sh2;
    seed7 >>= sh1;
    seed8 >>= sh2;
    seed9 >>= sh3;
    seed10 >>= sh3;
    seed11 >>= sh3;
    seed12 >>= sh3;

    int32_t a = seed1 * x + seed2 * y + seed11 * z + (rnum >> 14);
    int32_t b = seed3 * x + seed4 * y + seed12 * z + (rnum >> 10);
    int32_t c = seed5 * x + seed6 * y + seed9 * z + (rnum >> 6);
    int32_t d = seed7 * x + seed8 * y + seed10 * z + (rnum >> 2);

    a &= 0x3F;
    b &= 0x3F;
    c &= 0x3F;
    d &= 0x3F;

    if (partitionCount < 4)
        d = 0;
    if (partitionCount < 3)
        c = 0;

    if (a >= b && a >= c && a >= d)
        return 0;
    else if (b >= c && b >= d)
        return 1;
    else if (c >= d)
        return 2;
    return 3;
}

static inline uint32_t Select2DPartition(int32_t seed, int32_t x, int32_t y, int32_t partitionCount,
                                         int32_t smallBlock) {
    return SelectPartition(seed, x, y, 0, partitionCount, smallBlock);
}

// Section C.2.14
void ComputeEndpoints(Pixel& ep1, Pixel& ep2, const uint32_t*& colorValues,
                      uint32_t colorEndpointMode) {
#define READ_UINT_VALUES(N)                                                                        \
    uint32_t v[N];                                                                                 \
    for (uint32_t i = 0; i < N; i++) {                                                             \
        v[i] = *(colorValues++);                                                                   \
    }

#define READ_INT_VALUES(N)                                                                         \
    int32_t v[N];                                                                                  \
    for (uint32_t i = 0; i < N; i++) {                                                             \
        v[i] = static_cast<int32_t>(*(colorValues++));                                             \
    }

    switch (colorEndpointMode) {
    case 0: {
        READ_UINT_VALUES(2)
        ep1 = Pixel(0xFF, v[0], v[0], v[0]);
        ep2 = Pixel(0xFF, v[1], v[1], v[1]);
    } break;

    case 1: {
        READ_UINT_VALUES(2)
        uint32_t L0 = (v[0] >> 2) | (v[1] & 0xC0);
        uint32_t L1 = std::max(L0 + (v[1] & 0x3F), 0xFFU);
        ep1 = Pixel(0xFF, L0, L0, L0);
        ep2 = Pixel(0xFF, L1, L1, L1);
    } break;

    case 4: {
        READ_UINT_VALUES(4)
        ep1 = Pixel(v[2], v[0], v[0], v[0]);
        ep2 = Pixel(v[3], v[1], v[1], v[1]);
    } break;

    case 5: {
        READ_INT_VALUES(4)
        BitTransferSigned(v[1], v[0]);
        BitTransferSigned(v[3], v[2]);
        ep1 = Pixel(v[2], v[0], v[0], v[0]);
        ep2 = Pixel(v[2] + v[3], v[0] + v[1], v[0] + v[1], v[0] + v[1]);
        ep1.ClampByte();
        ep2.ClampByte();
    } break;

    case 6: {
        READ_UINT_VALUES(4)
        ep1 = Pixel(0xFF, v[0] * v[3] >> 8, v[1] * v[3] >> 8, v[2] * v[3] >> 8);
        ep2 = Pixel(0xFF, v[0], v[1], v[2]);
    } break;

    case 8: {
        READ_UINT_VALUES(6)
        if (v[1] + v[3] + v[5] >= v[0] + v[2] + v[4]) {
            ep1 = Pixel(0xFF, v[0], v[2], v[4]);
            ep2 = Pixel(0xFF, v[1], v[3], v[5]);
        } else {
            ep1 = BlueContract(0xFF, v[1], v[3], v[5]);
            ep2 = BlueContract(0xFF, v[0], v[2], v[4]);
        }
    } break;

    case 9: {
        READ_INT_VALUES(6)
        BitTransferSigned(v[1], v[0]);
        BitTransferSigned(v[3], v[2]);
        BitTransferSigned(v[5], v[4]);
        if (v[1] + v[3] + v[5] >= 0) {
            ep1 = Pixel(0xFF, v[0], v[2], v[4]);
            ep2 = Pixel(0xFF, v[0] + v[1], v[2] + v[3], v[4] + v[5]);
        } else {
            ep1 = BlueContract(0xFF, v[0] + v[1], v[2] + v[3], v[4] + v[5]);
            ep2 = BlueContract(0xFF, v[0], v[2], v[4]);
        }
        ep1.ClampByte();
        ep2.ClampByte();
    } break;

    case 10: {
        READ_UINT_VALUES(6)
        ep1 = Pixel(v[4], v[0] * v[3] >> 8, v[1] * v[3] >> 8, v[2] * v[3] >> 8);
        ep2 = Pixel(v[5], v[0], v[1], v[2]);
    } break;

    case 12: {
        READ_UINT_VALUES(8)
        if (v[1] + v[3] + v[5] >= v[0] + v[2] + v[4]) {
            ep1 = Pixel(v[6], v[0], v[2], v[4]);
            ep2 = Pixel(v[7], v[1], v[3], v[5]);
        } else {
            ep1 = BlueContract(v[7], v[1], v[3], v[5]);
            ep2 = BlueContract(v[6], v[0], v[2], v[4]);
        }
    } break;

    case 13: {
        READ_INT_VALUES(8)
        BitTransferSigned(v[1], v[0]);
        BitTransferSigned(v[3], v[2]);
        BitTransferSigned(v[5], v[4]);
        BitTransferSigned(v[7], v[6]);
        if (v[1] + v[3] + v[5] >= 0) {
            ep1 = Pixel(v[6], v[0], v[2], v[4]);
            ep2 = Pixel(v[7] + v[6], v[0] + v[1], v[2] + v[3], v[4] + v[5]);
        } else {
            ep1 = BlueContract(v[6] + v[7], v[0] + v[1], v[2] + v[3], v[4] + v[5]);
            ep2 = BlueContract(v[6], v[0], v[2], v[4]);
        }
        ep1.ClampByte();
        ep2.ClampByte();
    } break;

    default:
        assert(!"Unsupported color endpoint mode (is it HDR?)");
        break;
    }

#undef READ_UINT_VALUES
#undef READ_INT_VALUES
}

void DecompressBlock(uint8_t inBuf[16], const uint32_t blockWidth, const uint32_t blockHeight,
                     uint32_t* outBuf) {
    BitStream strm(inBuf);
    TexelWeightParams weightParams = DecodeBlockInfo(strm);

    // Was there an error?
    if (weightParams.m_bError) {
        assert(!"Invalid block mode");
        FillError(outBuf, blockWidth, blockHeight);
        return;
    }

    if (weightParams.m_bVoidExtentLDR) {
        FillVoidExtentLDR(strm, outBuf, blockWidth, blockHeight);
        return;
    }

    if (weightParams.m_bVoidExtentHDR) {
        assert(!"HDR void extent blocks are unsupported!");
        FillError(outBuf, blockWidth, blockHeight);
        return;
    }

    if (weightParams.m_Width > blockWidth) {
        assert(!"Texel weight grid width should be smaller than block width");
        FillError(outBuf, blockWidth, blockHeight);
        return;
    }

    if (weightParams.m_Height > blockHeight) {
        assert(!"Texel weight grid height should be smaller than block height");
        FillError(outBuf, blockWidth, blockHeight);
        return;
    }

    // Read num partitions
    uint32_t nPartitions = strm.ReadBits(2) + 1;
    assert(nPartitions <= 4);

    if (nPartitions == 4 && weightParams.m_bDualPlane) {
        assert(!"Dual plane mode is incompatible with four partition blocks");
        FillError(outBuf, blockWidth, blockHeight);
        return;
    }

    // Based on the number of partitions, read the color endpoint mode for
    // each partition.

    // Determine partitions, partition index, and color endpoint modes
    int32_t planeIdx = -1;
    uint32_t partitionIndex;
    uint32_t colorEndpointMode[4] = {0, 0, 0, 0};

    // Define color data.
    uint8_t colorEndpointData[16];
    memset(colorEndpointData, 0, sizeof(colorEndpointData));
    BitStream colorEndpointStream(colorEndpointData, 16 * 8, 0);

    // Read extra config data...
    uint32_t baseCEM = 0;
    if (nPartitions == 1) {
        colorEndpointMode[0] = strm.ReadBits(4);
        partitionIndex = 0;
    } else {
        partitionIndex = strm.ReadBits(10);
        baseCEM = strm.ReadBits(6);
    }
    uint32_t baseMode = (baseCEM & 3);

    // Remaining bits are color endpoint data...
    uint32_t nWeightBits = weightParams.GetPackedBitSize();
    int32_t remainingBits = 128 - nWeightBits - strm.GetBitsRead();

    // Consider extra bits prior to texel data...
    uint32_t extraCEMbits = 0;
    if (baseMode) {
        switch (nPartitions) {
        case 2:
            extraCEMbits += 2;
            break;
        case 3:
            extraCEMbits += 5;
            break;
        case 4:
            extraCEMbits += 8;
            break;
        default:
            assert(false);
            break;
        }
    }
    remainingBits -= extraCEMbits;

    // Do we have a dual plane situation?
    uint32_t planeSelectorBits = 0;
    if (weightParams.m_bDualPlane) {
        planeSelectorBits = 2;
    }
    remainingBits -= planeSelectorBits;

    // Read color data...
    uint32_t colorDataBits = remainingBits;
    while (remainingBits > 0) {
        uint32_t nb = std::min(remainingBits, 8);
        uint32_t b = strm.ReadBits(nb);
        colorEndpointStream.WriteBits(b, nb);
        remainingBits -= 8;
    }

    // Read the plane selection bits
    planeIdx = strm.ReadBits(planeSelectorBits);

    // Read the rest of the CEM
    if (baseMode) {
        uint32_t extraCEM = strm.ReadBits(extraCEMbits);
        uint32_t CEM = (extraCEM << 6) | baseCEM;
        CEM >>= 2;

        bool C[4] = {0};
        for (uint32_t i = 0; i < nPartitions; i++) {
            C[i] = CEM & 1;
            CEM >>= 1;
        }

        uint8_t M[4] = {0};
        for (uint32_t i = 0; i < nPartitions; i++) {
            M[i] = CEM & 3;
            CEM >>= 2;
            assert(M[i] <= 3);
        }

        for (uint32_t i = 0; i < nPartitions; i++) {
            colorEndpointMode[i] = baseMode;
            if (!(C[i]))
                colorEndpointMode[i] -= 1;
            colorEndpointMode[i] <<= 2;
            colorEndpointMode[i] |= M[i];
        }
    } else if (nPartitions > 1) {
        uint32_t CEM = baseCEM >> 2;
        for (uint32_t i = 0; i < nPartitions; i++) {
            colorEndpointMode[i] = CEM;
        }
    }

    // Make sure everything up till here is sane.
    for (uint32_t i = 0; i < nPartitions; i++) {
        assert(colorEndpointMode[i] < 16);
    }
    assert(strm.GetBitsRead() + weightParams.GetPackedBitSize() == 128);

    // Decode both color data and texel weight data
    uint32_t colorValues[32]; // Four values, two endpoints, four maximum paritions
    DecodeColorValues(colorValues, colorEndpointData, colorEndpointMode, nPartitions,
                      colorDataBits);

    Pixel endpoints[4][2];
    const uint32_t* colorValuesPtr = colorValues;
    for (uint32_t i = 0; i < nPartitions; i++) {
        ComputeEndpoints(endpoints[i][0], endpoints[i][1], colorValuesPtr, colorEndpointMode[i]);
    }

    // Read the texel weight data..
    uint8_t texelWeightData[16];
    memcpy(texelWeightData, inBuf, sizeof(texelWeightData));

    // Reverse everything
    for (uint32_t i = 0; i < 8; i++) {
// Taken from http://graphics.stanford.edu/~seander/bithacks.html#ReverseByteWith64Bits
#define REVERSE_BYTE(b) (((b)*0x80200802ULL) & 0x0884422110ULL) * 0x0101010101ULL >> 32
        unsigned char a = static_cast<unsigned char>(REVERSE_BYTE(texelWeightData[i]));
        unsigned char b = static_cast<unsigned char>(REVERSE_BYTE(texelWeightData[15 - i]));
#undef REVERSE_BYTE

        texelWeightData[i] = b;
        texelWeightData[15 - i] = a;
    }

    // Make sure that higher non-texel bits are set to zero
    const uint32_t clearByteStart = (weightParams.GetPackedBitSize() >> 3) + 1;
    texelWeightData[clearByteStart - 1] &= (1 << (weightParams.GetPackedBitSize() % 8)) - 1;
    memset(texelWeightData + clearByteStart, 0, 16 - clearByteStart);

    std::vector<IntegerEncodedValue> texelWeightValues;
    BitStream weightStream(texelWeightData);

    IntegerEncodedValue::DecodeIntegerSequence(texelWeightValues, weightStream,
                                               weightParams.m_MaxWeight,
                                               weightParams.GetNumWeightValues());

    // Blocks can be at most 12x12, so we can have as many as 144 weights
    uint32_t weights[2][144];
    UnquantizeTexelWeights(weights, texelWeightValues, weightParams, blockWidth, blockHeight);

    // Now that we have endpoints and weights, we can interpolate and generate
    // the proper decoding...
    for (uint32_t j = 0; j < blockHeight; j++)
        for (uint32_t i = 0; i < blockWidth; i++) {
            uint32_t partition = Select2DPartition(partitionIndex, i, j, nPartitions,
                                                   (blockHeight * blockWidth) < 32);
            assert(partition < nPartitions);

            Pixel p;
            for (uint32_t c = 0; c < 4; c++) {
                uint32_t C0 = endpoints[partition][0].Component(c);
                C0 = Replicate(C0, 8, 16);
                uint32_t C1 = endpoints[partition][1].Component(c);
                C1 = Replicate(C1, 8, 16);

                uint32_t plane = 0;
                if (weightParams.m_bDualPlane && (((planeIdx + 1) & 3) == c)) {
                    plane = 1;
                }

                uint32_t weight = weights[plane][j * blockWidth + i];
                uint32_t C = (C0 * (64 - weight) + C1 * weight + 32) / 64;
                if (C == 65535) {
                    p.Component(c) = 255;
                } else {
                    double Cf = static_cast<double>(C);
                    p.Component(c) = static_cast<uint16_t>(255.0 * (Cf / 65536.0) + 0.5);
                }
            }

            outBuf[j * blockWidth + i] = p.Pack();
        }
}

} // namespace ASTCC

namespace Tegra::Texture::ASTC {

std::vector<uint8_t> Decompress(std::vector<uint8_t>& data, uint32_t width, uint32_t height,
                                uint32_t block_width, uint32_t block_height) {
    uint32_t blockIdx = 0;
    std::vector<uint8_t> outData;
    outData.resize(height * width * 4);
    for (uint32_t j = 0; j < height; j += block_height) {
        for (uint32_t i = 0; i < width; i += block_width) {

            uint8_t* blockPtr = data.data() + blockIdx * 16;

            // Blocks can be at most 12x12
            uint32_t uncompData[144];
            ASTCC::DecompressBlock(blockPtr, block_width, block_height, uncompData);

            uint32_t decompWidth = std::min(block_width, width - i);
            uint32_t decompHeight = std::min(block_height, height - j);

            uint8_t* outRow = outData.data() + (j * width + i) * 4;
            for (uint32_t jj = 0; jj < decompHeight; jj++) {
                memcpy(outRow + jj * width * 4, uncompData + jj * block_width, decompWidth * 4);
            }

            blockIdx++;
        }
    }

    return outData;
}

} // namespace Tegra::Texture::ASTC