File: lodepng.cpp

package info (click to toggle)
doxygen 1.8.16-2
  • links: PTS, VCS
  • area: main
  • in suites: bullseye, sid
  • size: 22,176 kB
  • sloc: cpp: 245,005; lex: 37,843; ansic: 14,229; xml: 12,168; python: 3,038; tcl: 594; yacc: 576; php: 446; perl: 370; makefile: 213; objc: 14; sh: 11; cs: 5; f90: 4; java: 1
file content (2443 lines) | stat: -rw-r--r-- 94,053 bytes parent folder | download
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054
2055
2056
2057
2058
2059
2060
2061
2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095
2096
2097
2098
2099
2100
2101
2102
2103
2104
2105
2106
2107
2108
2109
2110
2111
2112
2113
2114
2115
2116
2117
2118
2119
2120
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
2133
2134
2135
2136
2137
2138
2139
2140
2141
2142
2143
2144
2145
2146
2147
2148
2149
2150
2151
2152
2153
2154
2155
2156
2157
2158
2159
2160
2161
2162
2163
2164
2165
2166
2167
2168
2169
2170
2171
2172
2173
2174
2175
2176
2177
2178
2179
2180
2181
2182
2183
2184
2185
2186
2187
2188
2189
2190
2191
2192
2193
2194
2195
2196
2197
2198
2199
2200
2201
2202
2203
2204
2205
2206
2207
2208
2209
2210
2211
2212
2213
2214
2215
2216
2217
2218
2219
2220
2221
2222
2223
2224
2225
2226
2227
2228
2229
2230
2231
2232
2233
2234
2235
2236
2237
2238
2239
2240
2241
2242
2243
2244
2245
2246
2247
2248
2249
2250
2251
2252
2253
2254
2255
2256
2257
2258
2259
2260
2261
2262
2263
2264
2265
2266
2267
2268
2269
2270
2271
2272
2273
2274
2275
2276
2277
2278
2279
2280
2281
2282
2283
2284
2285
2286
2287
2288
2289
2290
2291
2292
2293
2294
2295
2296
2297
2298
2299
2300
2301
2302
2303
2304
2305
2306
2307
2308
2309
2310
2311
2312
2313
2314
2315
2316
2317
2318
2319
2320
2321
2322
2323
2324
2325
2326
2327
2328
2329
2330
2331
2332
2333
2334
2335
2336
2337
2338
2339
2340
2341
2342
2343
2344
2345
2346
2347
2348
2349
2350
2351
2352
2353
2354
2355
2356
2357
2358
2359
2360
2361
2362
2363
2364
2365
2366
2367
2368
2369
2370
2371
2372
2373
2374
2375
2376
2377
2378
2379
2380
2381
2382
2383
2384
2385
2386
2387
2388
2389
2390
2391
2392
2393
2394
2395
2396
2397
2398
2399
2400
2401
2402
2403
2404
2405
2406
2407
2408
2409
2410
2411
2412
2413
2414
2415
2416
2417
2418
2419
2420
2421
2422
2423
2424
2425
2426
2427
2428
2429
2430
2431
2432
2433
2434
2435
2436
2437
2438
2439
2440
2441
2442
2443
/*
LodePNG version 20080927

Copyright (c) 2005-2008 Lode Vandevenne

This software is provided 'as-is', without any express or implied
warranty. In no event will the authors be held liable for any damages
arising from the use of this software.

Permission is granted to anyone to use this software for any purpose,
including commercial applications, and to alter it and redistribute it
freely, subject to the following restrictions:

    1. The origin of this software must not be misrepresented; you must not
    claim that you wrote the original software. If you use this software
    in a product, an acknowledgment in the product documentation would be
    appreciated but is not required.

    2. Altered source versions must be plainly marked as such, and must not be
    misrepresented as being the original software.

    3. This notice may not be removed or altered from any source
    distribution.
*/

/*
The manual and changelog can be found in the header file "lodepng.h"
You are free to name this file lodepng.cpp or lodepng.c depending on your usage.
*/

#include "lodepng.h"

#define USE_BRUTE_FORCE_ENCODING 1

#define VERSION_STRING "20080927"

/* ////////////////////////////////////////////////////////////////////////// */
/* / Tools For C                                                            / */
/* ////////////////////////////////////////////////////////////////////////// */

/*
About these tools (vector, uivector, ucvector and string):
-LodePNG was originally written in C++. The vectors replace the std::vectors that were used in the C++ version.
-The string tools are made to avoid problems with compilers that declare things like strncat as deprecated.
-They're not used in the interface, only internally in this file, so all their functions are made static.
*/

//--------------------------------------------------------------------------------------------


/*LodePNG_chunk functions: These functions need as input a large enough amount of allocated memory.*/

static unsigned LodePNG_chunk_length(const unsigned char* chunk); /*get the length of the data of the chunk. Total chunk length has 12 bytes more.*/

static void LodePNG_chunk_generate_crc(unsigned char* chunk); /*generates the correct CRC from the data and puts it in the last 4 bytes of the chunk*/

/*add chunks to out buffer. It reallocs the buffer to append the data. returns error code*/
static unsigned LodePNG_create_chunk(unsigned char** out, size_t* outlength, unsigned length, const char* type, const unsigned char* data); /*appends new chunk to out. Returns pointer to start of appended chunk, or NULL if error happened; may change memory address of out buffer*/

static void LodePNG_InfoColor_init(LodePNG_InfoColor* info);
static void LodePNG_InfoColor_cleanup(LodePNG_InfoColor* info);
static unsigned LodePNG_InfoColor_copy(LodePNG_InfoColor* dest, const LodePNG_InfoColor* source);

/*Use these functions instead of allocating palette manually*/
static void LodePNG_InfoColor_clearPalette(LodePNG_InfoColor* info);

/*additional color info*/
static unsigned LodePNG_InfoColor_getBpp(const LodePNG_InfoColor* info);      /*bits per pixel*/
static unsigned LodePNG_InfoColor_isGreyscaleType(const LodePNG_InfoColor* info); /*is it a greyscale type? (colorType 0 or 4)*/
static unsigned LodePNG_InfoColor_isAlphaType(const LodePNG_InfoColor* info);     /*has it an alpha channel? (colorType 2 or 6)*/

static void LodePNG_InfoPng_init(LodePNG_InfoPng* info);
static void LodePNG_InfoPng_cleanup(LodePNG_InfoPng* info);
static unsigned LodePNG_InfoPng_copy(LodePNG_InfoPng* dest, const LodePNG_InfoPng* source);

static void LodePNG_InfoRaw_init(LodePNG_InfoRaw* info);
static void LodePNG_InfoRaw_cleanup(LodePNG_InfoRaw* info);
static unsigned LodePNG_InfoRaw_copy(LodePNG_InfoRaw* dest, const LodePNG_InfoRaw* source);

/*
LodePNG_convert: Converts from any color type to 24-bit or 32-bit (later maybe more supported). return value = LodePNG error code
The out buffer must have (w * h * bpp + 7) / 8, where bpp is the bits per pixel of the output color type (LodePNG_InfoColor_getBpp)
*/
static unsigned LodePNG_convert(unsigned char* out, const unsigned char* in, LodePNG_InfoColor* infoOut, LodePNG_InfoColor* infoIn, unsigned w, unsigned h);

static void LodeZlib_DeflateSettings_init(LodeZlib_DeflateSettings* settings);

/* ////////////////////////////////////////////////////////////////////////// */
/* LodeFlate & LodeZlib                                                       */
/* ////////////////////////////////////////////////////////////////////////// */

/*This function reallocates the out buffer and appends the data.
Either, *out must be NULL and *outsize must be 0, or, *out must be a valid buffer and *outsize its size in bytes.*/
//unsigned LodeZlib_compress(unsigned char** out, size_t* outsize, const unsigned char* in, size_t insize, const LodeZlib_DeflateSettings* settings);

//--------------------------------------------------------------------------------------------

typedef struct vector /*this one is used only by the deflate compressor*/
{
  void* data;
  size_t size; /*in groups of bytes depending on type*/
  size_t allocsize; /*in bytes*/
  unsigned typesize; /*sizeof the type you store in data*/
} vector;

static unsigned vector_resize(vector* p, size_t size) /*returns 1 if success, 0 if failure ==> nothing done*/
{
  if(size * p->typesize > p->allocsize)
  {
    size_t newsize = size * p->typesize * 2;
    void* data = realloc(p->data, newsize);
    if(data)
    {
      p->allocsize = newsize;
      p->data = data;
      p->size = size;
    }
    else return 0;
  }
  else p->size = size;
  return 1;
}

static unsigned vector_resized(vector* p, size_t size, void dtor(void*)) /*resize and use destructor on elements if it gets smaller*/
{
  size_t i;
  if(size < p->size) for(i = size; i < p->size; i++) dtor(&((char*)(p->data))[i * p->typesize]);
  return vector_resize(p, size);
}

static void vector_cleanup(void* p)
{
  ((vector*)p)->size = ((vector*)p)->allocsize = 0;
  free(((vector*)p)->data);
  ((vector*)p)->data = NULL;
}

static void vector_cleanupd(vector* p, void dtor(void*)) /*clear and use destructor on elements*/
{
  vector_resized(p, 0, dtor);
  vector_cleanup(p);
}

static void vector_init(vector* p, unsigned typesize)
{
  p->data = NULL;
  p->size = p->allocsize = 0;
  p->typesize = typesize;
}

static void vector_swap(vector* p, vector* q) /*they're supposed to have the same typesize*/
{
  size_t tmp;
  void* tmpp;
  tmp = p->size; p->size = q->size; q->size = tmp;
  tmp = p->allocsize; p->allocsize = q->allocsize; q->allocsize = tmp;
  tmpp = p->data; p->data = q->data; q->data = tmpp;
}

static void* vector_get(vector* p, size_t index)
{
  return &((char*)p->data)[index * p->typesize];
}

/* /////////////////////////////////////////////////////////////////////////// */

typedef struct uivector
{
  unsigned* data;
  size_t size; /*size in number of unsigned longs*/
  size_t allocsize; /*allocated size in bytes*/
} uivector;

static void uivector_cleanup(void* p)
{
  ((uivector*)p)->size = ((uivector*)p)->allocsize = 0;
  free(((uivector*)p)->data);
  ((uivector*)p)->data = NULL;
}

static unsigned uivector_resize(uivector* p, size_t size) /*returns 1 if success, 0 if failure ==> nothing done*/
{
  if(size * sizeof(unsigned) > p->allocsize)
  {
    size_t newsize = size * sizeof(unsigned) * 2;
    void* data = realloc(p->data, newsize);
    if(data)
    {
      p->allocsize = newsize;
      p->data = (unsigned*)data;
      p->size = size;
    }
    else return 0;
  }
  else p->size = size;
  return 1;
}

static unsigned uivector_resizev(uivector* p, size_t size, unsigned value) /*resize and give all new elements the value*/
{
  size_t oldsize = p->size, i;
  if(!uivector_resize(p, size)) return 0;
  for(i = oldsize; i < size; i++) p->data[i] = value;
  return 1;
}

static void uivector_init(uivector* p)
{
  p->data = NULL;
  p->size = p->allocsize = 0;
}

static unsigned uivector_push_back(uivector* p, unsigned c) /*returns 1 if success, 0 if failure ==> nothing done*/
{
  if(!uivector_resize(p, p->size + 1)) return 0;
  p->data[p->size - 1] = c;
  return 1;
}

static unsigned uivector_copy(uivector* p, const uivector* q) /*copy q to p, returns 1 if success, 0 if failure ==> nothing done*/
{
  size_t i;
  if(!uivector_resize(p, q->size)) return 0;
  for(i = 0; i < q->size; i++) p->data[i] = q->data[i];
  return 1;
}

static void uivector_swap(uivector* p, uivector* q)
{
  size_t tmp;
  unsigned* tmpp;
  tmp = p->size; p->size = q->size; q->size = tmp;
  tmp = p->allocsize; p->allocsize = q->allocsize; q->allocsize = tmp;
  tmpp = p->data; p->data = q->data; q->data = tmpp;
}

/* /////////////////////////////////////////////////////////////////////////// */

typedef struct ucvector
{
  unsigned char* data;
  size_t size; /*used size*/
  size_t allocsize; /*allocated size*/
} ucvector;

static void ucvector_cleanup(void* p)
{
  ((ucvector*)p)->size = ((ucvector*)p)->allocsize = 0;
  free(((ucvector*)p)->data);
  ((ucvector*)p)->data = NULL;
}

static unsigned ucvector_resize(ucvector* p, size_t size) /*returns 1 if success, 0 if failure ==> nothing done*/
{
  if(size * sizeof(unsigned) > p->allocsize)
  {
    size_t newsize = size * sizeof(unsigned) * 2;
    void* data = realloc(p->data, newsize);
    if(data)
    {
      p->allocsize = newsize;
      p->data = (unsigned char*)data;
      p->size = size;
    }
    else return 0; /*error: not enough memory*/
  }
  else p->size = size;
  return 1;
}


static void ucvector_init(ucvector* p)
{
  p->data = NULL;
  p->size = p->allocsize = 0;
}

/*you can both convert from vector to buffer&size and vica versa*/
static void ucvector_init_buffer(ucvector* p, unsigned char* buffer, size_t size)
{
  p->data = buffer;
  p->allocsize = p->size = size;
}

static unsigned ucvector_push_back(ucvector* p, unsigned char c) /*returns 1 if success, 0 if failure ==> nothing done*/
{
  if(!ucvector_resize(p, p->size + 1)) return 0;
  p->data[p->size - 1] = c;
  return 1;
}

/* ////////////////////////////////////////////////////////////////////////// */
/* / Reading and writing single bits and bytes from/to stream for Deflate   / */
/* ////////////////////////////////////////////////////////////////////////// */

static void addBitToStream(size_t* bitpointer, ucvector* bitstream, unsigned char bit)
{
  if((*bitpointer) % 8 == 0) ucvector_push_back(bitstream, 0); /*add a new byte at the end*/
  (bitstream->data[bitstream->size - 1]) |= (bit << ((*bitpointer) & 0x7)); /*earlier bit of huffman code is in a lesser significant bit of an earlier byte*/
  (*bitpointer)++;
}

static void addBitsToStream(size_t* bitpointer, ucvector* bitstream, unsigned value, size_t nbits)
{
  size_t i;
  for(i = 0; i < nbits; i++) addBitToStream(bitpointer, bitstream, (unsigned char)((value >> i) & 1));
}

static void addBitsToStreamReversed(size_t* bitpointer, ucvector* bitstream, unsigned value, size_t nbits)
{
  size_t i;
  for(i = 0; i < nbits; i++) addBitToStream(bitpointer, bitstream, (unsigned char)((value >> (nbits - 1 - i)) & 1));
}


/* ////////////////////////////////////////////////////////////////////////// */
/* / Deflate - Huffman                                                      / */
/* ////////////////////////////////////////////////////////////////////////// */

#define FIRST_LENGTH_CODE_INDEX 257
#define LAST_LENGTH_CODE_INDEX 285
#define NUM_DEFLATE_CODE_SYMBOLS 288 /*256 literals, the end code, some length codes, and 2 unused codes*/
#define NUM_DISTANCE_SYMBOLS 32 /*the distance codes have their own symbols, 30 used, 2 unused*/
#define NUM_CODE_LENGTH_CODES 19 /*the code length codes. 0-15: code lengths, 16: copy previous 3-6 times, 17: 3-10 zeros, 18: 11-138 zeros*/

static const unsigned LENGTHBASE[29] /*the base lengths represented by codes 257-285*/
  = {3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 15, 17, 19, 23, 27, 31, 35, 43, 51, 59, 67, 83, 99, 115, 131, 163, 195, 227, 258};
static const unsigned LENGTHEXTRA[29] /*the extra bits used by codes 257-285 (added to base length)*/
  = {0, 0, 0, 0, 0, 0, 0,  0,  1,  1,  1,  1,  2,  2,  2,  2,  3,  3,  3,  3,  4,  4,  4,   4,   5,   5,   5,   5,   0};
static const unsigned DISTANCEBASE[30] /*the base backwards distances (the bits of distance codes appear after length codes and use their own huffman tree)*/
  = {1, 2, 3, 4, 5, 7, 9, 13, 17, 25, 33, 49, 65, 97, 129, 193, 257, 385, 513, 769, 1025, 1537, 2049, 3073, 4097, 6145, 8193, 12289, 16385, 24577};
static const unsigned DISTANCEEXTRA[30] /*the extra bits of backwards distances (added to base)*/
  = {0, 0, 0, 0, 1, 1, 2,  2,  3,  3,  4,  4,  5,  5,   6,   6,   7,   7,   8,   8,    9,    9,   10,   10,   11,   11,   12,    12,    13,    13};
static const unsigned CLCL[NUM_CODE_LENGTH_CODES] /*the order in which "code length alphabet code lengths" are stored, out of this the huffman tree of the dynamic huffman tree lengths is generated*/
  = {16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15};

/* /////////////////////////////////////////////////////////////////////////// */

/*terminology used for the package-merge algorithm and the coin collector's problem*/
typedef struct Coin /*a coin can be multiple coins (when they're merged)*/
{
  uivector symbols;
  float weight; /*the sum of all weights in this coin*/
} Coin;

static void Coin_init(Coin* c)
{
  uivector_init(&c->symbols);
}

static void Coin_cleanup(void* c) /*void* so that this dtor can be given as function pointer to the vector resize function*/
{
  uivector_cleanup(&((Coin*)c)->symbols);
}

static void Coin_copy(Coin* c1, const Coin* c2)
{
  c1->weight = c2->weight;
  uivector_copy(&c1->symbols, &c2->symbols);
}

static void addCoins(Coin* c1, const Coin* c2)
{
  unsigned i;
  for(i = 0; i < c2->symbols.size; i++) uivector_push_back(&c1->symbols, c2->symbols.data[i]);
  c1->weight += c2->weight;
}

static void Coin_sort(Coin* data, size_t amount) /*combsort*/
{
  size_t gap = amount;
  unsigned char swapped = 0;
  while(gap > 1 || swapped)
  {
    size_t i;
    gap = (gap * 10) / 13; /*shrink factor 1.3*/
    if(gap == 9 || gap == 10) gap = 11; /*combsort11*/
    if(gap < 1) gap = 1;
    swapped = 0;
    for(i = 0; i < amount - gap; i++)
    {
      size_t j = i + gap;
      if(data[j].weight < data[i].weight)
      {
        float temp = data[j].weight; data[j].weight = data[i].weight; data[i].weight = temp;
        uivector_swap(&data[i].symbols, &data[j].symbols);
        swapped = 1;
      }
    }
  }
}

typedef struct HuffmanTree
{
  uivector tree2d;
  uivector tree1d;
  uivector lengths; /*the lengths of the codes of the 1d-tree*/
  unsigned maxbitlen; /*maximum number of bits a single code can get*/
  unsigned numcodes; /*number of symbols in the alphabet = number of codes*/
} HuffmanTree;

/*function used for debug purposes*/
/*#include <iostream>
static void HuffmanTree_draw(HuffmanTree* tree)
{
  std::cout << "tree. length: " << tree->numcodes << " maxbitlen: " << tree->maxbitlen << std::endl;
  for(size_t i = 0; i < tree->tree1d.size; i++)
  {
    if(tree->lengths.data[i])
      std::cout << i << " " << tree->tree1d.data[i] << " " << tree->lengths.data[i] << std::endl;
  }
  std::cout << std::endl;
}*/

static void HuffmanTree_init(HuffmanTree* tree)
{
  uivector_init(&tree->tree2d);
  uivector_init(&tree->tree1d);
  uivector_init(&tree->lengths);
}

static void HuffmanTree_cleanup(HuffmanTree* tree)
{
  uivector_cleanup(&tree->tree2d);
  uivector_cleanup(&tree->tree1d);
  uivector_cleanup(&tree->lengths);
}

/*the tree representation used by the decoder. return value is error*/
static unsigned HuffmanTree_make2DTree(HuffmanTree* tree)
{
  unsigned nodefilled = 0; /*up to which node it is filled*/
  unsigned treepos = 0; /*position in the tree (1 of the numcodes columns)*/
  unsigned n, i;

  if(!uivector_resize(&tree->tree2d, tree->numcodes * 2)) return 9901; /*if failed return not enough memory error*/
  /*convert tree1d[] to tree2d[][]. In the 2D array, a value of 32767 means uninited, a value >= numcodes is an address to another bit, a value < numcodes is a code. The 2 rows are the 2 possible bit values (0 or 1), there are as many columns as codes - 1
  a good huffmann tree has N * 2 - 1 nodes, of which N - 1 are internal nodes. Here, the internal nodes are stored (what their 0 and 1 option point to). There is only memory for such good tree currently, if there are more nodes (due to too long length codes), error 55 will happen*/
  for(n = 0;  n < tree->numcodes * 2; n++) tree->tree2d.data[n] = 32767; /*32767 here means the tree2d isn't filled there yet*/

  for(n = 0; n < tree->numcodes; n++) /*the codes*/
  for(i = 0; i < tree->lengths.data[n]; i++) /*the bits for this code*/
  {
    unsigned char bit = (unsigned char)((tree->tree1d.data[n] >> (tree->lengths.data[n] - i - 1)) & 1);
    if(treepos > tree->numcodes - 2) return 55; /*error 55: oversubscribed; see description in header*/
    if(tree->tree2d.data[2 * treepos + bit] == 32767) /*not yet filled in*/
    {
      if(i + 1 == tree->lengths.data[n]) /*last bit*/
      {
        tree->tree2d.data[2 * treepos + bit] = n; /*put the current code in it*/
        treepos = 0;
      }
      else /*put address of the next step in here, first that address has to be found of course (it's just nodefilled + 1)...*/
      {
        nodefilled++;
        tree->tree2d.data[2 * treepos + bit] = nodefilled + tree->numcodes; /*addresses encoded with numcodes added to it*/
        treepos = nodefilled;
      }
    }
    else treepos = tree->tree2d.data[2 * treepos + bit] - tree->numcodes;
  }
  for(n = 0;  n < tree->numcodes * 2; n++) if(tree->tree2d.data[n] == 32767) tree->tree2d.data[n] = 0; /*remove possible remaining 32767's*/

  return 0;
}

static unsigned HuffmanTree_makeFromLengths2(HuffmanTree* tree) /*given that numcodes, lengths and maxbitlen are already filled in correctly. return value is error.*/
{
  uivector blcount;
  uivector nextcode;
  unsigned bits, n, error = 0;

  uivector_init(&blcount);
  uivector_init(&nextcode);
  if(!uivector_resize(&tree->tree1d, tree->numcodes)
  || !uivector_resizev(&blcount, tree->maxbitlen + 1, 0)
  || !uivector_resizev(&nextcode, tree->maxbitlen + 1, 0))
    error = 9902;

  if(!error)
  {
    /*step 1: count number of instances of each code length*/
    for(bits = 0; bits < tree->numcodes; bits++) blcount.data[tree->lengths.data[bits]]++;
    /*step 2: generate the nextcode values*/
    for(bits = 1; bits <= tree->maxbitlen; bits++) nextcode.data[bits] = (nextcode.data[bits - 1] + blcount.data[bits - 1]) << 1;
    /*step 3: generate all the codes*/
    for(n = 0; n < tree->numcodes; n++) if(tree->lengths.data[n] != 0) tree->tree1d.data[n] = nextcode.data[tree->lengths.data[n]]++;
  }

  uivector_cleanup(&blcount);
  uivector_cleanup(&nextcode);

  if(!error) return HuffmanTree_make2DTree(tree);
  else return error;
}

/*given the code lengths (as stored in the PNG file), generate the tree as defined by Deflate. maxbitlen is the maximum bits that a code in the tree can have. return value is error.*/
static unsigned HuffmanTree_makeFromLengths(HuffmanTree* tree, const unsigned* bitlen, size_t numcodes, unsigned maxbitlen)
{
  unsigned i;
  if(!uivector_resize(&tree->lengths, numcodes)) return 9903;
  for(i = 0; i < numcodes; i++) tree->lengths.data[i] = bitlen[i];
  tree->numcodes = (unsigned)numcodes; /*number of symbols*/
  tree->maxbitlen = maxbitlen;
  return HuffmanTree_makeFromLengths2(tree);
}

static unsigned HuffmanTree_fillInCoins(vector* coins, const unsigned* frequencies, unsigned numcodes, size_t sum)
{
  unsigned i;
  for(i = 0; i < numcodes; i++)
  {
    Coin* coin;
    if(frequencies[i] == 0) continue; /*it's important to exclude symbols that aren't present*/
    if(!vector_resize(coins, coins->size + 1)) { vector_cleanup(coins); return 9904; }
    coin = (Coin*)(vector_get(coins, coins->size - 1));
    Coin_init(coin);
    coin->weight = frequencies[i] / (float)sum;
    uivector_push_back(&coin->symbols, i);
  }
  if(coins->size) Coin_sort((Coin*)coins->data, coins->size);
  return 0;
}

static unsigned HuffmanTree_makeFromFrequencies(HuffmanTree* tree, const unsigned* frequencies, size_t numcodes, unsigned maxbitlen)
{
  unsigned i, j;
  size_t sum = 0, numpresent = 0;
  unsigned error = 0;

  vector prev_row; /*type Coin, the previous row of coins*/
  vector coins; /*type Coin, the coins of the currently calculated row*/

  tree->maxbitlen = maxbitlen;

  for(i = 0; i < numcodes; i++)
  {
    if(frequencies[i] > 0)
    {
      numpresent++;
      sum += frequencies[i];
    }
  }

  if(numcodes == 0) return 80; /*error: a tree of 0 symbols is not supposed to be made*/
  tree->numcodes = (unsigned)numcodes; /*number of symbols*/
  uivector_resize(&tree->lengths, 0);
  if(!uivector_resizev(&tree->lengths, tree->numcodes, 0)) return 9905;

  if(numpresent == 0) /*there are no symbols at all, in that case add one symbol of value 0 to the tree (see RFC 1951 section 3.2.7) */
  {
    tree->lengths.data[0] = 1;
    return HuffmanTree_makeFromLengths2(tree);
  }
  else if(numpresent == 1) /*the package merge algorithm gives wrong results if there's only one symbol (theoretically 0 bits would then suffice, but we need a proper symbol for zlib)*/
  {
    for(i = 0; i < numcodes; i++) if(frequencies[i]) tree->lengths.data[i] = 1;
    return HuffmanTree_makeFromLengths2(tree);
  }

  vector_init(&coins, sizeof(Coin));
  vector_init(&prev_row, sizeof(Coin));

  /*Package-Merge algorithm represented by coin collector's problem
  For every symbol, maxbitlen coins will be created*/

  /*first row, lowest denominator*/
  error = HuffmanTree_fillInCoins(&coins, frequencies, tree->numcodes, sum);
  if(!error)
  {
    for(j = 1; j <= maxbitlen && !error; j++) /*each of the remaining rows*/
    {
      vector_swap(&coins, &prev_row); /*swap instead of copying*/
      if(!vector_resized(&coins, 0, Coin_cleanup)) { error = 9906; break; }

      for(i = 0; i + 1 < prev_row.size; i += 2)
      {
        if(!vector_resize(&coins, coins.size + 1)) { error = 9907; break; }
        Coin_init((Coin*)vector_get(&coins, coins.size - 1));
        Coin_copy((Coin*)vector_get(&coins, coins.size - 1), (Coin*)vector_get(&prev_row, i));
        addCoins((Coin*)vector_get(&coins, coins.size - 1), (Coin*)vector_get(&prev_row, i + 1)); /*merge the coins into packages*/
      }
      if(j < maxbitlen)
      {
        error = HuffmanTree_fillInCoins(&coins, frequencies, tree->numcodes, sum);
      }
    }
  }

  if(!error)
  {
    /*keep the coins with lowest weight, so that they add up to the amount of symbols - 1*/
    vector_resized(&coins, numpresent - 1, Coin_cleanup);

    /*calculate the lengths of each symbol, as the amount of times a coin of each symbol is used*/
    for(i = 0; i < coins.size; i++)
    {
      Coin* coin = (Coin*)vector_get(&coins, i);
      for(j = 0; j < coin->symbols.size; j++) tree->lengths.data[coin->symbols.data[j]]++;
    }

    error = HuffmanTree_makeFromLengths2(tree);
  }

  vector_cleanupd(&coins, Coin_cleanup);
  vector_cleanupd(&prev_row, Coin_cleanup);

  return error;
}

static unsigned HuffmanTree_getCode(const HuffmanTree* tree, unsigned index) { return tree->tree1d.data[index]; }
static unsigned HuffmanTree_getLength(const HuffmanTree* tree, unsigned index) { return tree->lengths.data[index]; }

/*get the tree of a deflated block with fixed tree, as specified in the deflate specification*/
static unsigned generateFixedTree(HuffmanTree* tree)
{
  unsigned i, error = 0;
  uivector bitlen;
  uivector_init(&bitlen);
  if(!uivector_resize(&bitlen, NUM_DEFLATE_CODE_SYMBOLS)) error = 9909;

  if(!error)
  {
    /*288 possible codes: 0-255=literals, 256=endcode, 257-285=lengthcodes, 286-287=unused*/
    for(i =   0; i <= 143; i++) bitlen.data[i] = 8;
    for(i = 144; i <= 255; i++) bitlen.data[i] = 9;
    for(i = 256; i <= 279; i++) bitlen.data[i] = 7;
    for(i = 280; i <= 287; i++) bitlen.data[i] = 8;

    error = HuffmanTree_makeFromLengths(tree, bitlen.data, NUM_DEFLATE_CODE_SYMBOLS, 15);
  }

  uivector_cleanup(&bitlen);
  return error;
}

static unsigned generateDistanceTree(HuffmanTree* tree)
{
  unsigned i, error = 0;
  uivector bitlen;
  uivector_init(&bitlen);
  if(!uivector_resize(&bitlen, NUM_DISTANCE_SYMBOLS)) error = 9910;

  /*there are 32 distance codes, but 30-31 are unused*/
  if(!error)
  {
    for(i = 0; i < NUM_DISTANCE_SYMBOLS; i++) bitlen.data[i] = 5;
    error = HuffmanTree_makeFromLengths(tree, bitlen.data, NUM_DISTANCE_SYMBOLS, 15);
  }
  uivector_cleanup(&bitlen);
  return error;
}

/* ////////////////////////////////////////////////////////////////////////// */
/* / Deflator                                                               / */
/* ////////////////////////////////////////////////////////////////////////// */

static const size_t MAX_SUPPORTED_DEFLATE_LENGTH = 258;

/*bitlen is the size in bits of the code*/
static void addHuffmanSymbol(size_t* bp, ucvector* compressed, unsigned code, unsigned bitlen)
{
  addBitsToStreamReversed(bp, compressed, code, bitlen);
}

/*search the index in the array, that has the largest value smaller than or equal to the given value, given array must be sorted (if no value is smaller, it returns the size of the given array)*/
static size_t searchCodeIndex(const unsigned* array, size_t array_size, size_t value)
{
  /*linear search implementation*/
  /*for(size_t i = 1; i < array_size; i++) if(array[i] > value) return i - 1;
  return array_size - 1;*/

  /*binary search implementation (not that much faster) (precondition: array_size > 0)*/
  size_t left  = 1;
  size_t right = array_size - 1;
  while(left <= right)
  {
    size_t mid = (left + right) / 2;
    if(array[mid] <= value) left = mid + 1; /*the value to find is more to the right*/
    else if(array[mid - 1] > value) right = mid - 1; /*the value to find is more to the left*/
    else return mid - 1;
  }
  return array_size - 1;
}

static void addLengthDistance(uivector* values, size_t length, size_t distance)
{
  /*values in encoded vector are those used by deflate:
  0-255: literal bytes
  256: end
  257-285: length/distance pair (length code, followed by extra length bits, distance code, extra distance bits)
  286-287: invalid*/

  unsigned length_code = (unsigned)searchCodeIndex(LENGTHBASE, 29, length);
  unsigned extra_length = (unsigned)(length - LENGTHBASE[length_code]);
  unsigned dist_code = (unsigned)searchCodeIndex(DISTANCEBASE, 30, distance);
  unsigned extra_distance = (unsigned)(distance - DISTANCEBASE[dist_code]);

  uivector_push_back(values, length_code + FIRST_LENGTH_CODE_INDEX);
  uivector_push_back(values, extra_length);
  uivector_push_back(values, dist_code);
  uivector_push_back(values, extra_distance);
}

#if USE_BRUTE_FORCE_ENCODING
#define encodeLZ77 encodeLZ77_brute
/*the "brute force" version of the encodeLZ7 algorithm, not used anymore, kept here for reference*/
static unsigned encodeLZ77_brute(uivector* out, const unsigned char* in, size_t size, unsigned windowSize)
{
  size_t pos;
  /*using pointer instead of vector for input makes it faster when NOT using optimization when compiling; no influence if optimization is used*/
  for(pos = 0; pos < size; pos++)
  {
    /*Phase 1: doxygen images often have long runs of the same color, try to find them*/
    const int minLength = 4; // Minimum length for a run to make sense

    if(pos < size - minLength * 4)
    {
      size_t p, fp;
      size_t current_length;

      /*RGBA pixel run?*/
      p  = pos;
      fp = pos + 4;
      current_length = 0;

      while(fp < size && in[p] == in[fp] && current_length < MAX_SUPPORTED_DEFLATE_LENGTH)
      {
        ++p;
        ++fp;
        ++current_length;
      }

      if (current_length > (minLength - 1 ) * 4) /*worth using?*/
      {
        uivector_push_back(out, in[pos    ]);
        uivector_push_back(out, in[pos + 1]);
        uivector_push_back(out, in[pos + 2]);
        uivector_push_back(out, in[pos + 3]);
        addLengthDistance(out, current_length, 4);

        pos += current_length + 4 - 1; /*-1 for loop's pos++*/
        continue;
      }

      /*RGB pixel run?*/
      p  = pos;
      fp = pos + 3;
      current_length = 0;

      while(fp < size && in[p] == in[fp] && current_length < MAX_SUPPORTED_DEFLATE_LENGTH)
      {
        ++p;
        ++fp;
        ++current_length;
      }

      if (current_length > (minLength - 1 ) * 3) /*worth using?*/
      {
        uivector_push_back(out, in[pos    ]);
        uivector_push_back(out, in[pos + 1]);
        uivector_push_back(out, in[pos + 2]);
        addLengthDistance(out, current_length, 3);

        pos += current_length + 3 - 1; /*-1 for loop's pos++*/
        continue;
      }
    }

    size_t length = 0, offset = 0; /*the length and offset found for the current position*/
    size_t max_offset = pos < windowSize ? pos : windowSize; /*how far back to test*/
    size_t current_offset;

    /**search for the longest string**/
    for(current_offset = 1; current_offset < max_offset; current_offset++) /*search backwards through all possible distances (=offsets)*/
    {
      size_t backpos = pos - current_offset;
      if(in[backpos] == in[pos])
      {
        /*test the next characters*/
        size_t current_length = 1;
        size_t backtest = backpos + 1;
        size_t foretest = pos + 1;
        while(foretest < size && in[backtest] == in[foretest] && current_length < MAX_SUPPORTED_DEFLATE_LENGTH) /*maximum support length by deflate is max length*/
        {
          if(backpos >= pos) backpos -= current_offset; /*continue as if we work on the decoded bytes after pos by jumping back before pos*/
          current_length++;
          backtest++;
          foretest++;
        }
        if(current_length > length)
        {
          length = current_length; /*the longest length*/
          offset = current_offset; /*the offset that is related to this longest length*/
          if(current_length == MAX_SUPPORTED_DEFLATE_LENGTH) break; /*you can jump out of this for loop once a length of max length is found (gives significant speed gain)*/
        }
      }
    }

    /**encode it as length/distance pair or literal value**/
    if(length < 3) /*only lengths of 3 or higher are supported as length/distance pair*/
    {
      uivector_push_back(out, in[pos]);
    }
    else
    {
      addLengthDistance(out, length, offset);
      pos += (length - 1);
    }
  } /*end of the loop through each character of input*/

  return 0;
}
#endif

/*
static const unsigned HASH_NUM_VALUES = 65536;
static const unsigned HASH_NUM_CHARACTERS = 6;
static const unsigned HASH_SHIFT = 2;
Good and fast values: HASH_NUM_VALUES=65536, HASH_NUM_CHARACTERS=6, HASH_SHIFT=2
making HASH_NUM_CHARACTERS larger (like 8), makes the file size larger but is a bit faster
making HASH_NUM_CHARACTERS smaller (like 3), makes the file size smaller but is slower
*/

#if !defined(USE_BRUTE_FORCE_ENCODING)
static unsigned getHash(const unsigned char* data, size_t size, size_t pos)
{
  unsigned result = 0;
  size_t amount, i;
  if(pos >= size) return 0;
  amount = HASH_NUM_CHARACTERS; if(pos + amount >= size) amount = size - pos;
  for(i = 0; i < amount; i++) result ^= (data[pos + i] << (i * HASH_SHIFT));
  return result % HASH_NUM_VALUES;
}

/*LZ77-encode the data using a hash table technique to let it encode faster. Return value is error code*/
static unsigned encodeLZ77(uivector* out, const unsigned char* in, size_t size, unsigned windowSize)
{
  /**generate hash table**/
  vector table; /*HASH_NUM_VALUES uivectors; this represents what would be an std::vector<std::vector<unsigned> > in C++*/
  uivector tablepos1, tablepos2;
  unsigned pos, i, error = 0;

  vector_init(&table, sizeof(uivector));
  if(!vector_resize(&table, HASH_NUM_VALUES)) return 9917;
  for(i = 0; i < HASH_NUM_VALUES; i++)
  {
    uivector* v = (uivector*)vector_get(&table, i);
    uivector_init(v);
  }

  /*remember start and end positions in the tables to searching in*/
  uivector_init(&tablepos1);
  uivector_init(&tablepos2);
  if(!uivector_resizev(&tablepos1, HASH_NUM_VALUES, 0)) error = 9918;
  if(!uivector_resizev(&tablepos2, HASH_NUM_VALUES, 0)) error = 9919;

  if(!error)
  {
    for(pos = 0; pos < size; pos++)
    {
      unsigned length = 0, offset = 0; /*the length and offset found for the current position*/
      unsigned max_offset = pos < windowSize ? pos : windowSize; /*how far back to test*/
      unsigned tablepos;

      /*/search for the longest string*/
      /*first find out where in the table to start (the first value that is in the range from "pos - max_offset" to "pos")*/
      unsigned hash = getHash(in, size, pos);
      if(!uivector_push_back((uivector*)vector_get(&table, hash), pos))  { error = 9920; break; }

      while(((uivector*)vector_get(&table, hash))->data[tablepos1.data[hash]] < pos - max_offset) tablepos1.data[hash]++; /*it now points to the first value in the table for which the index is larger than or equal to pos - max_offset*/
      while(((uivector*)vector_get(&table, hash))->data[tablepos2.data[hash]] < pos) tablepos2.data[hash]++; /*it now points to the first value in the table for which the index is larger than or equal to pos*/

      for(tablepos = tablepos2.data[hash] - 1; tablepos >= tablepos1.data[hash] && tablepos < tablepos2.data[hash]; tablepos--)
      {
        unsigned backpos = ((uivector*)vector_get(&table, hash))->data[tablepos];
        unsigned current_offset = pos - backpos;

        /*test the next characters*/
        unsigned current_length = 0;
        unsigned backtest = backpos;
        unsigned foretest = pos;
        while(foretest < size && in[backtest] == in[foretest] && current_length < MAX_SUPPORTED_DEFLATE_LENGTH) /*maximum support length by deflate is max length*/
        {
          if(backpos >= pos) backpos -= current_offset; /*continue as if we work on the decoded bytes after pos by jumping back before pos*/
          current_length++;
          backtest++;
          foretest++;
        }
        if(current_length > length)
        {
          length = current_length; /*the longest length*/
          offset = current_offset; /*the offset that is related to this longest length*/
          if(current_length == MAX_SUPPORTED_DEFLATE_LENGTH) break; /*you can jump out of this for loop once a length of max length is found (gives significant speed gain)*/
        }
      }

      /**encode it as length/distance pair or literal value**/
      if(length < 3) /*only lengths of 3 or higher are supported as length/distance pair*/
      {
        if(!uivector_push_back(out, in[pos])) { error = 9921; break; }
      }
      else
      {
        unsigned j;
        addLengthDistance(out, length, offset);
        for(j = 0; j < length - 1; j++)
        {
          pos++;
          if(!uivector_push_back((uivector*)vector_get(&table, getHash(in, size, pos)), pos)) { error = 9922; break; }
        }
      }
    } /*end of the loop through each character of input*/
  } /*end of "if(!error)"*/

  /*cleanup*/
  for(i = 0; i < table.size; i++)
  {
    uivector* v = (uivector*)vector_get(&table, i);
    uivector_cleanup(v);
  }
  vector_cleanup(&table);
  uivector_cleanup(&tablepos1);
  uivector_cleanup(&tablepos2);
  return error;
}
#endif

/* /////////////////////////////////////////////////////////////////////////// */

static unsigned deflateNoCompression(ucvector* out, const unsigned char* data, size_t datasize)
{
  /*non compressed deflate block data: 1 bit BFINAL,2 bits BTYPE,(5 bits): it jumps to start of next byte, 2 bytes LEN, 2 bytes NLEN, LEN bytes literal DATA*/

  size_t i, j, numdeflateblocks = datasize / 65536 + 1;
  unsigned datapos = 0;
  for(i = 0; i < numdeflateblocks; i++)
  {
    unsigned BFINAL, BTYPE, LEN, NLEN;
    unsigned char firstbyte;

    BFINAL = (i == numdeflateblocks - 1);
    BTYPE = 0;

    firstbyte = (unsigned char)(BFINAL + ((BTYPE & 1) << 1) + ((BTYPE & 2) << 1));
    ucvector_push_back(out, firstbyte);

    LEN = 65535;
    if(datasize - datapos < 65535) LEN = (unsigned)datasize - datapos;
    NLEN = 65535 - LEN;

    ucvector_push_back(out, (unsigned char)(LEN % 256));
    ucvector_push_back(out, (unsigned char)(LEN / 256));
    ucvector_push_back(out, (unsigned char)(NLEN % 256));
    ucvector_push_back(out, (unsigned char)(NLEN / 256));

    /*Decompressed data*/
    for(j = 0; j < 65535 && datapos < datasize; j++)
    {
      ucvector_push_back(out, data[datapos++]);
    }
  }

  return 0;
}

/*write the encoded data, using lit/len as well as distance codes*/
static void writeLZ77data(size_t* bp, ucvector* out, const uivector* lz77_encoded, const HuffmanTree* codes, const HuffmanTree* codesD)
{
  size_t i = 0;
  for(i = 0; i < lz77_encoded->size; i++)
  {
    unsigned val = lz77_encoded->data[i];
    addHuffmanSymbol(bp, out, HuffmanTree_getCode(codes, val), HuffmanTree_getLength(codes, val));
    if(val > 256) /*for a length code, 3 more things have to be added*/
    {
      unsigned length_index = val - FIRST_LENGTH_CODE_INDEX;
      unsigned n_length_extra_bits = LENGTHEXTRA[length_index];
      unsigned length_extra_bits = lz77_encoded->data[++i];

      unsigned distance_code = lz77_encoded->data[++i];

      unsigned distance_index = distance_code;
      unsigned n_distance_extra_bits = DISTANCEEXTRA[distance_index];
      unsigned distance_extra_bits = lz77_encoded->data[++i];

      addBitsToStream(bp, out, length_extra_bits, n_length_extra_bits);
      addHuffmanSymbol(bp, out, HuffmanTree_getCode(codesD, distance_code), HuffmanTree_getLength(codesD, distance_code));
      addBitsToStream(bp, out, distance_extra_bits, n_distance_extra_bits);
    }
  }
}

static unsigned deflateDynamic(ucvector* out, const unsigned char* data, size_t datasize, const LodeZlib_DeflateSettings* settings)
{
  /*
  after the BFINAL and BTYPE, the dynamic block consists out of the following:
  - 5 bits HLIT, 5 bits HDIST, 4 bits HCLEN
  - (HCLEN+4)*3 bits code lengths of code length alphabet
  - HLIT + 257 code lengths of lit/length alphabet (encoded using the code length alphabet, + possible repetition codes 16, 17, 18)
  - HDIST + 1 code lengths of distance alphabet (encoded using the code length alphabet, + possible repetition codes 16, 17, 18)
  - compressed data
  - 256 (end code)
  */

  unsigned error = 0;

  uivector lz77_encoded;
  HuffmanTree codes; /*tree for literal values and length codes*/
  HuffmanTree codesD; /*tree for distance codes*/
  HuffmanTree codelengthcodes;
  uivector frequencies;
  uivector frequenciesD;
  uivector amounts; /*the amounts in the "normal" order*/
  uivector lldl;
  uivector lldll; /*lit/len & dist code lengths*/
  uivector clcls;

  unsigned BFINAL = 1; /*make only one block... the first and final one*/
  size_t numcodes, numcodesD, i, bp = 0; /*the bit pointer*/
  unsigned HLIT, HDIST, HCLEN;

  uivector_init(&lz77_encoded);
  HuffmanTree_init(&codes);
  HuffmanTree_init(&codesD);
  HuffmanTree_init(&codelengthcodes);
  uivector_init(&frequencies);
  uivector_init(&frequenciesD);
  uivector_init(&amounts);
  uivector_init(&lldl);
  uivector_init(&lldll);
  uivector_init(&clcls);

  while(!error) /*the goto-avoiding while construct: break out to go to the cleanup phase, a break at the end makes sure the while is never repeated*/
  {
    if(settings->useLZ77)
    {
      error = encodeLZ77(&lz77_encoded, data, datasize, settings->windowSize); /*LZ77 encoded*/
      if(error) break;
    }
    else
    {
      if(!uivector_resize(&lz77_encoded, datasize)) { error = 9923; break; }
      for(i = 0; i < datasize; i++) lz77_encoded.data[i] = data[i]; /*no LZ77, but still will be Huffman compressed*/
    }

    if(!uivector_resizev(&frequencies, 286, 0)) { error = 9924; break; }
    if(!uivector_resizev(&frequenciesD, 30, 0)) { error = 9925; break; }
    for(i = 0; i < lz77_encoded.size; i++)
    {
      unsigned symbol = lz77_encoded.data[i];
      frequencies.data[symbol]++;
      if(symbol > 256)
      {
        unsigned dist = lz77_encoded.data[i + 2];
        frequenciesD.data[dist]++;
        i += 3;
      }
    }
    frequencies.data[256] = 1; /*there will be exactly 1 end code, at the end of the block*/

    error = HuffmanTree_makeFromFrequencies(&codes, frequencies.data, frequencies.size, 15);
    if(error) break;
    error = HuffmanTree_makeFromFrequencies(&codesD, frequenciesD.data, frequenciesD.size, 15);
    if(error) break;

    addBitToStream(&bp, out, BFINAL);
    addBitToStream(&bp, out, 0); /*first bit of BTYPE "dynamic"*/
    addBitToStream(&bp, out, 1); /*second bit of BTYPE "dynamic"*/

    numcodes = codes.numcodes; if(numcodes > 286) numcodes = 286;
    numcodesD = codesD.numcodes; if(numcodesD > 30) numcodesD = 30;
    for(i = 0; i < numcodes; i++) uivector_push_back(&lldll, HuffmanTree_getLength(&codes, (unsigned)i));
    for(i = 0; i < numcodesD; i++) uivector_push_back(&lldll, HuffmanTree_getLength(&codesD, (unsigned)i));

    /*make lldl smaller by using repeat codes 16 (copy length 3-6 times), 17 (3-10 zeros), 18 (11-138 zeros)*/
    for(i = 0; i < (unsigned)lldll.size; i++)
    {
      unsigned j = 0;
      while(i + j + 1 < (unsigned)lldll.size && lldll.data[i + j + 1] == lldll.data[i]) j++;

      if(lldll.data[i] == 0 && j >= 2)
      {
        j++; /*include the first zero*/
        if(j <= 10) { uivector_push_back(&lldl, 17); uivector_push_back(&lldl, j - 3); }
        else
        {
          if(j > 138) j = 138;
          uivector_push_back(&lldl, 18); uivector_push_back(&lldl, j - 11);
        }
        i += (j - 1);
      }
      else if(j >= 3)
      {
        size_t k;
        unsigned num = j / 6, rest = j % 6;
        uivector_push_back(&lldl, lldll.data[i]);
        for(k = 0; k < num; k++) { uivector_push_back(&lldl, 16); uivector_push_back(&lldl,    6 - 3); }
        if(rest >= 3)            { uivector_push_back(&lldl, 16); uivector_push_back(&lldl, rest - 3); }
        else j -= rest;
        i += j;
      }
      else uivector_push_back(&lldl, lldll.data[i]);
    }

    /*generate huffmantree for the length codes of lit/len and dist codes*/
    if(!uivector_resizev(&amounts, 19, 0)) { error = 9926; break; } /*16 possible lengths (0-15) and 3 repeat codes (16, 17 and 18)*/
    for(i = 0; i < lldl.size; i++)
    {
      amounts.data[lldl.data[i]]++;
      if(lldl.data[i] >= 16) i++; /*after a repeat code come the bits that specify the amount, those don't need to be in the amounts calculation*/
    }

    error = HuffmanTree_makeFromFrequencies(&codelengthcodes, amounts.data, amounts.size, 7);
    if(error) break;

    if(!uivector_resize(&clcls, 19)) { error = 9927; break; }
    for(i = 0; i < 19; i++) clcls.data[i] = HuffmanTree_getLength(&codelengthcodes, CLCL[i]); /*lengths of code length tree is in the order as specified by deflate*/
    while(clcls.data[clcls.size - 1] == 0 && clcls.size > 4)
    {
      if(!uivector_resize(&clcls, clcls.size - 1)) { error = 9928; break; } /*remove zeros at the end, but minimum size must be 4*/
    }
    if(error) break;

    /*write the HLIT, HDIST and HCLEN values*/
    HLIT = (unsigned)(numcodes - 257);
    HDIST = (unsigned)(numcodesD - 1);
    HCLEN = (unsigned)clcls.size - 4;
    addBitsToStream(&bp, out, HLIT, 5);
    addBitsToStream(&bp, out, HDIST, 5);
    addBitsToStream(&bp, out, HCLEN, 4);

    /*write the code lengths of the code length alphabet*/
    for(i = 0; i < HCLEN + 4; i++) addBitsToStream(&bp, out, clcls.data[i], 3);

    /*write the lengths of the lit/len AND the dist alphabet*/
    for(i = 0; i < lldl.size; i++)
    {
      addHuffmanSymbol(&bp, out, HuffmanTree_getCode(&codelengthcodes, lldl.data[i]), HuffmanTree_getLength(&codelengthcodes, lldl.data[i]));
      /*extra bits of repeat codes*/
      if(lldl.data[i] == 16) addBitsToStream(&bp, out, lldl.data[++i], 2);
      else if(lldl.data[i] == 17) addBitsToStream(&bp, out, lldl.data[++i], 3);
      else if(lldl.data[i] == 18) addBitsToStream(&bp, out, lldl.data[++i], 7);
    }

    /*write the compressed data symbols*/
    writeLZ77data(&bp, out, &lz77_encoded, &codes, &codesD);
    if(HuffmanTree_getLength(&codes, 256) == 0) { error = 64; break; } /*the length of the end code 256 must be larger than 0*/
    addHuffmanSymbol(&bp, out, HuffmanTree_getCode(&codes, 256), HuffmanTree_getLength(&codes, 256)); /*end code*/

    break; /*end of error-while*/
  }

  /*cleanup*/
  uivector_cleanup(&lz77_encoded);
  HuffmanTree_cleanup(&codes);
  HuffmanTree_cleanup(&codesD);
  HuffmanTree_cleanup(&codelengthcodes);
  uivector_cleanup(&frequencies);
  uivector_cleanup(&frequenciesD);
  uivector_cleanup(&amounts);
  uivector_cleanup(&lldl);
  uivector_cleanup(&lldll);
  uivector_cleanup(&clcls);

  return error;
}

static unsigned deflateFixed(ucvector* out, const unsigned char* data, size_t datasize, const LodeZlib_DeflateSettings* settings)
{
  HuffmanTree codes; /*tree for literal values and length codes*/
  HuffmanTree codesD; /*tree for distance codes*/

  unsigned BFINAL = 1; /*make only one block... the first and final one*/
  unsigned error = 0;
  size_t i, bp = 0; /*the bit pointer*/

  HuffmanTree_init(&codes);
  HuffmanTree_init(&codesD);

  generateFixedTree(&codes);
  generateDistanceTree(&codesD);

  addBitToStream(&bp, out, BFINAL);
  addBitToStream(&bp, out, 1); /*first bit of BTYPE*/
  addBitToStream(&bp, out, 0); /*second bit of BTYPE*/

  if(settings->useLZ77) /*LZ77 encoded*/
  {
    uivector lz77_encoded;
    uivector_init(&lz77_encoded);
    error = encodeLZ77(&lz77_encoded, data, datasize, settings->windowSize);
    if(!error) writeLZ77data(&bp, out, &lz77_encoded, &codes, &codesD);
    uivector_cleanup(&lz77_encoded);
  }
  else /*no LZ77, but still will be Huffman compressed*/
  {
    for(i = 0; i < datasize; i++) addHuffmanSymbol(&bp, out, HuffmanTree_getCode(&codes, data[i]), HuffmanTree_getLength(&codes, data[i]));
  }
  if(!error) addHuffmanSymbol(&bp, out, HuffmanTree_getCode(&codes, 256), HuffmanTree_getLength(&codes, 256)); /*"end" code*/

  /*cleanup*/
  HuffmanTree_cleanup(&codes);
  HuffmanTree_cleanup(&codesD);

  return error;
}

unsigned LodeFlate_deflate(ucvector* out, const unsigned char* data, size_t datasize, const LodeZlib_DeflateSettings* settings)
{
  unsigned error = 0;
  if(settings->btype == 0) error = deflateNoCompression(out, data, datasize);
  else if(settings->btype == 1) error = deflateFixed(out, data, datasize, settings);
  else if(settings->btype == 2) error = deflateDynamic(out, data, datasize, settings);
  else error = 61;
  return error;
}


/* ////////////////////////////////////////////////////////////////////////// */
/* / Adler32                                                                  */
/* ////////////////////////////////////////////////////////////////////////// */

static unsigned update_adler32(unsigned adler, const unsigned char* data, unsigned len)
{
   unsigned s1 = adler & 0xffff;
   unsigned s2 = (adler >> 16) & 0xffff;

  while(len > 0)
  {
    /*at least 5550 sums can be done before the sums overflow, saving us from a lot of module divisions*/
    unsigned amount = len > 5550 ? 5550 : len;
    len -= amount;
    while(amount > 0)
    {
      s1 = (s1 + *data++);
      s2 = (s2 + s1);
      amount--;
    }
    s1 %= 65521;
    s2 %= 65521;
  }

  return (s2 << 16) | s1;
}

/*Return the adler32 of the bytes data[0..len-1]*/
static unsigned adler32(const unsigned char* data, unsigned len)
{
  return update_adler32(1L, data, len);
}

/* ////////////////////////////////////////////////////////////////////////// */
/* / Reading and writing single bits and bytes from/to stream for Zlib      / */
/* ////////////////////////////////////////////////////////////////////////// */

static void LodeZlib_add32bitInt(ucvector* buffer, unsigned value)
{
  ucvector_push_back(buffer, (unsigned char)((value >> 24) & 0xff));
  ucvector_push_back(buffer, (unsigned char)((value >> 16) & 0xff));
  ucvector_push_back(buffer, (unsigned char)((value >>  8) & 0xff));
  ucvector_push_back(buffer, (unsigned char)((value      ) & 0xff));
}

/* ////////////////////////////////////////////////////////////////////////// */
/* / Zlib                                                                   / */
/* ////////////////////////////////////////////////////////////////////////// */

static unsigned LodeZlib_compress(unsigned char** out, size_t* outsize, const unsigned char* in, size_t insize, const LodeZlib_DeflateSettings* settings)
{
  /*initially, *out must be NULL and outsize 0, if you just give some random *out that's pointing to a non allocated buffer, this'll crash*/
  ucvector deflatedata, outv;
  size_t i;
  unsigned error;

  unsigned ADLER32;
  /*zlib data: 1 byte CMF (CM+CINFO), 1 byte FLG, deflate data, 4 byte ADLER32 checksum of the Decompressed data*/
  unsigned CMF = 120; /*0b01111000: CM 8, CINFO 7. With CINFO 7, any window size up to 32768 can be used.*/
  unsigned FLEVEL = 0;
  unsigned FDICT = 0;
  unsigned CMFFLG = 256 * CMF + FDICT * 32 + FLEVEL * 64;
  unsigned FCHECK = 31 - CMFFLG % 31;
  CMFFLG += FCHECK;

  ucvector_init_buffer(&outv, *out, *outsize); /*ucvector-controlled version of the output buffer, for dynamic array*/

  ucvector_push_back(&outv, (unsigned char)(CMFFLG / 256));
  ucvector_push_back(&outv, (unsigned char)(CMFFLG % 256));

  ucvector_init(&deflatedata);
  error = LodeFlate_deflate(&deflatedata, in, insize, settings);

  if(!error)
  {
    ADLER32 = adler32(in, (unsigned)insize);
    for(i = 0; i < deflatedata.size; i++) ucvector_push_back(&outv, deflatedata.data[i]);
    ucvector_cleanup(&deflatedata);
    LodeZlib_add32bitInt(&outv, ADLER32);
  }

  *out = outv.data;
  *outsize = outv.size;

  return error;
}

/* ////////////////////////////////////////////////////////////////////////// */

void LodeZlib_DeflateSettings_init(LodeZlib_DeflateSettings* settings)
{
  settings->btype = 2; /*compress with dynamic huffman tree (not in the mathematical sense, just not the predefined one)*/
  settings->useLZ77 = 1;
  settings->windowSize = 2048; /*this is a good tradeoff between speed and compression ratio*/
}

/* ////////////////////////////////////////////////////////////////////////// */
/* ////////////////////////////////////////////////////////////////////////// */
/* ////////////////////////////////////////////////////////////////////////// */
/* ////////////////////////////////////////////////////////////////////////// */
/* ////////////////////////////////////////////////////////////////////////// */
/* // End of Zlib related code, now comes the PNG related code that uses it// */
/* ////////////////////////////////////////////////////////////////////////// */
/* ////////////////////////////////////////////////////////////////////////// */
/* ////////////////////////////////////////////////////////////////////////// */
/* ////////////////////////////////////////////////////////////////////////// */
/* ////////////////////////////////////////////////////////////////////////// */

/*
The two functions below (LodePNG_decompress and LodePNG_compress) directly call the
LodeZlib_decompress and LodeZlib_compress functions. The only purpose of the functions
below, is to provide the ability to let LodePNG use a different Zlib encoder by only
changing the two functions below, instead of changing it inside the various places
in the other LodePNG functions.

*out must be NULL and *outsize must be 0 initially, and after the function is done,
*out must point to the decompressed data, *outsize must be the size of it, and must
be the size of the useful data in bytes, not the alloc size.
*/

static unsigned LodePNG_compress(unsigned char** out, size_t* outsize, const unsigned char* in, size_t insize, const LodeZlib_DeflateSettings* settings)
{
  return LodeZlib_compress(out, outsize, in, insize, settings);
}

/* ////////////////////////////////////////////////////////////////////////// */
/* / CRC32                                                                  / */
/* ////////////////////////////////////////////////////////////////////////// */

static unsigned Crc32_crc_table_computed = 0;
static unsigned Crc32_crc_table[256];

/*Make the table for a fast CRC.*/
static void Crc32_make_crc_table(void)
{
  unsigned int c, k, n;
  for(n = 0; n < 256; n++)
  {
    c = n;
    for(k = 0; k < 8; k++)
    {
      if(c & 1) c = (unsigned int)(0xedb88320L ^ (c >> 1));
      else c = c >> 1;
    }
    Crc32_crc_table[n] = c;
  }
  Crc32_crc_table_computed = 1;
}

/*Update a running CRC with the bytes buf[0..len-1]--the CRC should be
initialized to all 1's, and the transmitted value is the 1's complement of the
final running CRC (see the crc() routine below).*/
static unsigned Crc32_update_crc(const unsigned char* buf, unsigned int crc, size_t len)
{
  unsigned int c = crc;
  size_t n;

  if(!Crc32_crc_table_computed) Crc32_make_crc_table();
  for(n = 0; n < len; n++)
  {
    c = Crc32_crc_table[(c ^ buf[n]) & 0xff] ^ (c >> 8);
  }
  return c;
}

/*Return the CRC of the bytes buf[0..len-1].*/
static unsigned Crc32_crc(const unsigned char* buf, size_t len)
{
  return Crc32_update_crc(buf, 0xffffffffu, len) ^ 0xffffffffu;
}

/* ////////////////////////////////////////////////////////////////////////// */
/* / Reading and writing single bits and bytes from/to stream for LodePNG   / */
/* ////////////////////////////////////////////////////////////////////////// */

static unsigned char readBitFromReversedStream(size_t* bitpointer, const unsigned char* bitstream)
{
  unsigned char result = (unsigned char)((bitstream[(*bitpointer) >> 3] >> (7 - ((*bitpointer) & 0x7))) & 1);
  (*bitpointer)++;
  return result;
}

static unsigned readBitsFromReversedStream(size_t* bitpointer, const unsigned char* bitstream, size_t nbits)
{
  unsigned result = 0;
  size_t i;
  for(i = nbits - 1; i < nbits; i--) result += (unsigned)readBitFromReversedStream(bitpointer, bitstream) << i;
  return result;
}

static void setBitOfReversedStream(size_t* bitpointer, unsigned char* bitstream, unsigned char bit)
{
  /*the current bit in bitstream may be 0 or 1 for this to work*/
  if(bit == 0) bitstream[(*bitpointer) >> 3] &=  (unsigned char)(~(1 << (7 - ((*bitpointer) & 0x7))));
  else bitstream[(*bitpointer) >> 3] |=  (1 << (7 - ((*bitpointer) & 0x7)));
  (*bitpointer)++;
}

static unsigned LodePNG_read32bitInt(const unsigned char* buffer)
{
  return (buffer[0] << 24) | (buffer[1] << 16) | (buffer[2] << 8) | buffer[3];
}

static void LodePNG_set32bitInt(unsigned char* buffer, unsigned value) /*buffer must have at least 4 allocated bytes available*/
{
  buffer[0] = (unsigned char)((value >> 24) & 0xff);
  buffer[1] = (unsigned char)((value >> 16) & 0xff);
  buffer[2] = (unsigned char)((value >>  8) & 0xff);
  buffer[3] = (unsigned char)((value      ) & 0xff);
}

static void LodePNG_add32bitInt(ucvector* buffer, unsigned value)
{
  ucvector_resize(buffer, buffer->size + 4);
  LodePNG_set32bitInt(&buffer->data[buffer->size - 4], value);
}

/* ////////////////////////////////////////////////////////////////////////// */
/* / PNG chunks                                                             / */
/* ////////////////////////////////////////////////////////////////////////// */

static unsigned LodePNG_chunk_length(const unsigned char* chunk) /*get the length of the data of the chunk. Total chunk length has 12 bytes more.*/
{
  return LodePNG_read32bitInt(&chunk[0]);
}

static void LodePNG_chunk_generate_crc(unsigned char* chunk) /*generates the correct CRC from the data and puts it in the last 4 bytes of the chunk*/
{
  unsigned length = LodePNG_chunk_length(chunk);
  unsigned CRC = Crc32_crc(&chunk[4], length + 4);
  LodePNG_set32bitInt(chunk + 8 + length, CRC);
}

static unsigned LodePNG_create_chunk(unsigned char** out, size_t* outlength, unsigned length, const char* type, const unsigned char* data) /*appends new chunk to out. Returns error code; may change memory address of out buffer*/
{
  unsigned i;
  unsigned char *chunk, *new_buffer;
  size_t new_length = (*outlength) + length + 12;
  if(new_length < length + 12 || new_length < (*outlength)) return 77; /*integer overflow happened*/
  new_buffer = (unsigned char*)realloc(*out, new_length);
  if(!new_buffer) return 9930;
  (*out) = new_buffer;
  (*outlength) = new_length;
  chunk = &(*out)[(*outlength) - length - 12];

  /*1: length*/
  LodePNG_set32bitInt(chunk, (unsigned)length);

  /*2: chunk name (4 letters)*/
  chunk[4] = type[0];
  chunk[5] = type[1];
  chunk[6] = type[2];
  chunk[7] = type[3];

  /*3: the data*/
  for(i = 0; i < length; i++) chunk[8 + i] = data[i];

  /*4: CRC (of the chunkname characters and the data)*/
  LodePNG_chunk_generate_crc(chunk);

  return 0;
}

/* ////////////////////////////////////////////////////////////////////////// */
/* / Color types and such                                                   / */
/* ////////////////////////////////////////////////////////////////////////// */

/*return type is a LodePNG error code*/
static unsigned checkColorValidity(unsigned colorType, unsigned bd) /*bd = bitDepth*/
{
  switch(colorType)
  {
    case 0: if(!(bd == 1 || bd == 2 || bd == 4 || bd == 8 || bd == 16)) return 37; break; /*grey*/
    case 2: if(!(                                 bd == 8 || bd == 16)) return 37; break; /*RGB*/
    case 3: if(!(bd == 1 || bd == 2 || bd == 4 || bd == 8            )) return 37; break; /*palette*/
    case 4: if(!(                                 bd == 8 || bd == 16)) return 37; break; /*grey + alpha*/
    case 6: if(!(                                 bd == 8 || bd == 16)) return 37; break; /*RGBA*/
    default: return 31;
  }
  return 0; /*allowed color type / bits combination*/
}

static unsigned getNumColorChannels(unsigned colorType)
{
  switch(colorType)
  {
    case 0: return 1; /*grey*/
    case 2: return 3; /*RGB*/
    case 3: return 1; /*palette*/
    case 4: return 2; /*grey + alpha*/
    case 6: return 4; /*RGBA*/
  }
  return 0; /*unexisting color type*/
}

static unsigned getBpp(unsigned colorType, unsigned bitDepth)
{
  return getNumColorChannels(colorType) * bitDepth; /*bits per pixel is amount of channels * bits per channel*/
}

/* ////////////////////////////////////////////////////////////////////////// */

static void LodePNG_InfoColor_init(LodePNG_InfoColor* info)
{
  info->key_defined = 0;
  info->key_r = info->key_g = info->key_b = 0;
  info->colorType = 6;
  info->bitDepth = 8;
  info->palette = 0;
  info->palettesize = 0;
}

static void LodePNG_InfoColor_cleanup(LodePNG_InfoColor* info)
{
  LodePNG_InfoColor_clearPalette(info);
}

static void LodePNG_InfoColor_clearPalette(LodePNG_InfoColor* info)
{
  if(info->palette) free(info->palette);
  info->palettesize = 0;
}

unsigned LodePNG_InfoColor_addPalette(LodePNG_InfoColor* info, unsigned char r, unsigned char g, unsigned char b, unsigned char a)
{
  unsigned char* data;
  /*the same resize technique as C++ std::vectors is used, and here it's made so that for a palette with the max of 256 colors, it'll have the exact alloc size*/
  if(!(info->palettesize & (info->palettesize - 1))) /*if palettesize is 0 or a power of two*/
  {
    /*allocated data must be at least 4* palettesize (for 4 color bytes)*/
    size_t alloc_size = info->palettesize == 0 ? 4 : info->palettesize * 4 * 2;
    data = (unsigned char*)realloc(info->palette, alloc_size);
    if(!data) return 9931;
    else info->palette = data;
  }
  info->palette[4 * info->palettesize + 0] = r;
  info->palette[4 * info->palettesize + 1] = g;
  info->palette[4 * info->palettesize + 2] = b;
  info->palette[4 * info->palettesize + 3] = a;
  info->palettesize++;
  return 0;
}

static unsigned LodePNG_InfoColor_getBpp(const LodePNG_InfoColor* info) { return getBpp(info->colorType, info->bitDepth); } /*calculate bits per pixel out of colorType and bitDepth*/
static unsigned LodePNG_InfoColor_isGreyscaleType(const LodePNG_InfoColor* info) { return info->colorType == 0 || info->colorType == 4; }
static unsigned LodePNG_InfoColor_isAlphaType(const LodePNG_InfoColor* info) { return (info->colorType & 4) != 0; }

static unsigned LodePNG_InfoColor_equal(const LodePNG_InfoColor* info1, const LodePNG_InfoColor* info2)
{
  return info1->colorType == info2->colorType
      && info1->bitDepth  == info2->bitDepth; /*palette and color key not compared*/
}


static void LodePNG_InfoPng_init(LodePNG_InfoPng* info)
{
  info->width = info->height = 0;
  LodePNG_InfoColor_init(&info->color);
  info->interlaceMethod = 0;
  info->compressionMethod = 0;
  info->filterMethod = 0;
}

static void LodePNG_InfoPng_cleanup(LodePNG_InfoPng* info)
{
  LodePNG_InfoColor_cleanup(&info->color);
}

static unsigned LodePNG_InfoPng_copy(LodePNG_InfoPng* dest, const LodePNG_InfoPng* source)
{
  unsigned error = 0;
  LodePNG_InfoPng_cleanup(dest);
  *dest = *source;
  LodePNG_InfoColor_init(&dest->color);
  error = LodePNG_InfoColor_copy(&dest->color, &source->color); if(error) return error;
  return error;
}

static unsigned LodePNG_InfoColor_copy(LodePNG_InfoColor* dest, const LodePNG_InfoColor* source)
{
  size_t i;
  LodePNG_InfoColor_cleanup(dest);
  *dest = *source;
  dest->palette = (unsigned char*)malloc(source->palettesize * 4);
  if(!dest->palette && source->palettesize) return 9935;
  for(i = 0; i < source->palettesize * 4; i++) dest->palette[i] = source->palette[i];
  return 0;
}

static void LodePNG_InfoRaw_init(LodePNG_InfoRaw* info)
{
  LodePNG_InfoColor_init(&info->color);
}

static void LodePNG_InfoRaw_cleanup(LodePNG_InfoRaw* info)
{
  LodePNG_InfoColor_cleanup(&info->color);
}

static unsigned LodePNG_InfoRaw_copy(LodePNG_InfoRaw* dest, const LodePNG_InfoRaw* source)
{
  unsigned error = 0;
  LodePNG_InfoRaw_cleanup(dest);
  *dest = *source;
  LodePNG_InfoColor_init(&dest->color);
  error = LodePNG_InfoColor_copy(&dest->color, &source->color);
  return error;
}

/* ////////////////////////////////////////////////////////////////////////// */

/*
converts from any color type to 24-bit or 32-bit (later maybe more supported). return value = LodePNG error code
the out buffer must have (w * h * bpp + 7) / 8 bytes, where bpp is the bits per pixel of the output color type (LodePNG_InfoColor_getBpp)
for < 8 bpp images, there may _not_ be padding bits at the end of scanlines.
*/
static unsigned LodePNG_convert(unsigned char* out, const unsigned char* in, LodePNG_InfoColor* infoOut, LodePNG_InfoColor* infoIn, unsigned w, unsigned h)
{
  const size_t numpixels = w * h; /*amount of pixels*/
  const unsigned OUT_BYTES = LodePNG_InfoColor_getBpp(infoOut) / 8; /*bytes per pixel in the output image*/
  const unsigned OUT_ALPHA = LodePNG_InfoColor_isAlphaType(infoOut); /*use 8-bit alpha channel*/
  size_t i, c, bp = 0; /*bitpointer, used by less-than-8-bit color types*/

  /*cases where in and out already have the same format*/
  if(LodePNG_InfoColor_equal(infoIn, infoOut))
  {
    size_t i, size = (w * h * LodePNG_InfoColor_getBpp(infoIn) + 7) / 8;
    for(i = 0; i < size; i++) out[i] = in[i];
    return 0;
  }

  if((infoOut->colorType == 2 || infoOut->colorType == 6) && infoOut->bitDepth == 8)
  {
    if(infoIn->bitDepth == 8)
    {
      switch(infoIn->colorType)
      {
        case 0: /*greyscale color*/
          for(i = 0; i < numpixels; i++)
          {
            if(OUT_ALPHA) out[OUT_BYTES * i + 3] = 255;
            out[OUT_BYTES * i + 0] = out[OUT_BYTES * i + 1] = out[OUT_BYTES * i + 2] = in[i];
            if(OUT_ALPHA && infoIn->key_defined && in[i] == infoIn->key_r) out[OUT_BYTES * i + 3] = 0;
          }
        break;
        case 2: /*RGB color*/
          for(i = 0; i < numpixels; i++)
          {
            if(OUT_ALPHA) out[OUT_BYTES * i + 3] = 255;
            for(c = 0; c < 3; c++) out[OUT_BYTES * i + c] = in[3 * i + c];
            if(OUT_ALPHA && infoIn->key_defined == 1 && in[3 * i + 0] == infoIn->key_r && in[3 * i + 1] == infoIn->key_g && in[3 * i + 2] == infoIn->key_b) out[OUT_BYTES * i + 3] = 0;
          }
        break;
        case 3: /*indexed color (palette)*/
          for(i = 0; i < numpixels; i++)
          {
            if(OUT_ALPHA) out[OUT_BYTES * i + 3] = 255;
            if(in[i] >= infoIn->palettesize) return 46;
            for(c = 0; c < OUT_BYTES; c++) out[OUT_BYTES * i + c] = infoIn->palette[4 * in[i] + c]; /*get rgb colors from the palette*/
          }
        break;
        case 4: /*greyscale with alpha*/
          for(i = 0; i < numpixels; i++)
          {
            out[OUT_BYTES * i + 0] = out[OUT_BYTES * i + 1] = out[OUT_BYTES * i + 2] = in[2 * i + 0];
            if(OUT_ALPHA) out[OUT_BYTES * i + 3] = in[2 * i + 1];
          }
        break;
        case 6: /*RGB with alpha*/
          for(i = 0; i < numpixels; i++)
          {
            for(c = 0; c < OUT_BYTES; c++) out[OUT_BYTES * i + c] = in[4 * i + c];
          }
        break;
        default: break;
      }
    }
    else if(infoIn->bitDepth == 16)
    {
      switch(infoIn->colorType)
      {
        case 0: /*greyscale color*/
          for(i = 0; i < numpixels; i++)
          {
            if(OUT_ALPHA) out[OUT_BYTES * i + 3] = 255;
            out[OUT_BYTES * i + 0] = out[OUT_BYTES * i + 1] = out[OUT_BYTES * i + 2] = in[2 * i];
            if(OUT_ALPHA && infoIn->key_defined && 256U * in[i] + in[i + 1] == infoIn->key_r) out[OUT_BYTES * i + 3] = 0;
          }
        break;
        case 2: /*RGB color*/
          for(i = 0; i < numpixels; i++)
          {
            if(OUT_ALPHA) out[OUT_BYTES * i + 3] = 255;
            for(c = 0; c < 3; c++) out[OUT_BYTES * i + c] = in[6 * i + 2 * c];
            if(OUT_ALPHA && infoIn->key_defined && 256U * in[6 * i + 0] + in[6 * i + 1] == infoIn->key_r && 256U * in[6 * i + 2] + in[6 * i + 3] == infoIn->key_g && 256U * in[6 * i + 4] + in[6 * i + 5] == infoIn->key_b) out[OUT_BYTES * i + 3] = 0;
          }
        break;
        case 4: /*greyscale with alpha*/
          for(i = 0; i < numpixels; i++)
          {
            out[OUT_BYTES * i + 0] = out[OUT_BYTES * i + 1] = out[OUT_BYTES * i + 2] = in[4 * i]; /*most significant byte*/
            if(OUT_ALPHA) out[OUT_BYTES * i + 3] = in[4 * i + 2];
          }
        break;
        case 6: /*RGB with alpha*/
          for(i = 0; i < numpixels; i++)
          {
            for(c = 0; c < OUT_BYTES; c++) out[OUT_BYTES * i + c] = in[8 * i + 2 * c];
          }
          break;
        default: break;
      }
    }
    else /*infoIn->bitDepth is less than 8 bit per channel*/
    {
      switch(infoIn->colorType)
      {
        case 0: /*greyscale color*/
          for(i = 0; i < numpixels; i++)
          {
            unsigned value = readBitsFromReversedStream(&bp, in, infoIn->bitDepth);
            if(OUT_ALPHA) out[OUT_BYTES * i + 3] = 255;
            if(OUT_ALPHA && infoIn->key_defined && value && ((1U << infoIn->bitDepth) - 1U) == infoIn->key_r && ((1U << infoIn->bitDepth) - 1U)) out[OUT_BYTES * i + 3] = 0;
            value = (value * 255) / ((1 << infoIn->bitDepth) - 1); /*scale value from 0 to 255*/
            out[OUT_BYTES * i + 0] = out[OUT_BYTES * i + 1] = out[OUT_BYTES * i + 2] = (unsigned char)(value);
          }
        break;
        case 3: /*indexed color (palette)*/
          for(i = 0; i < numpixels; i++)
          {
            unsigned value = readBitsFromReversedStream(&bp, in, infoIn->bitDepth);
            if(OUT_ALPHA) out[OUT_BYTES * i + 3] = 255;
            if(value >= infoIn->palettesize) return 47;
            for(c = 0; c < OUT_BYTES; c++) out[OUT_BYTES * i + c] = infoIn->palette[4 * value + c]; /*get rgb colors from the palette*/
          }
        break;
        default: break;
      }
    }
  }
  else if(LodePNG_InfoColor_isGreyscaleType(infoOut) && infoOut->bitDepth == 8) /*conversion from greyscale to greyscale*/
  {
    if(!LodePNG_InfoColor_isGreyscaleType(infoIn)) return 62;
    if(infoIn->bitDepth == 8)
    {
      switch(infoIn->colorType)
      {
        case 0: /*greyscale color*/
          for(i = 0; i < numpixels; i++)
          {
            if(OUT_ALPHA) out[OUT_BYTES * i + 1] = 255;
            out[OUT_BYTES * i] = in[i];
            if(OUT_ALPHA && infoIn->key_defined && in[i] == infoIn->key_r) out[OUT_BYTES * i + 1] = 0;
          }
        break;
        case 4: /*greyscale with alpha*/
          for(i = 0; i < numpixels; i++)
          {
            out[OUT_BYTES * i + 0] = in[2 * i + 0];
            if(OUT_ALPHA) out[OUT_BYTES * i + 1] = in[2 * i + 1];
          }
        break;
        default: return 31;
      }
    }
    else if(infoIn->bitDepth == 16)
    {
      switch(infoIn->colorType)
      {
        case 0: /*greyscale color*/
          for(i = 0; i < numpixels; i++)
          {
            if(OUT_ALPHA) out[OUT_BYTES * i + 1] = 255;
            out[OUT_BYTES * i] = in[2 * i];
            if(OUT_ALPHA && infoIn->key_defined && 256U * in[i] + in[i + 1] == infoIn->key_r) out[OUT_BYTES * i + 1] = 0;
          }
        break;
        case 4: /*greyscale with alpha*/
          for(i = 0; i < numpixels; i++)
          {
            out[OUT_BYTES * i] = in[4 * i]; /*most significant byte*/
            if(OUT_ALPHA) out[OUT_BYTES * i + 1] = in[4 * i + 2]; /*most significant byte*/
          }
        break;
        default: return 31;
      }
    }
    else /*infoIn->bitDepth is less than 8 bit per channel*/
    {
      if(infoIn->colorType != 0) return 31; /*colorType 0 is the only greyscale type with < 8 bits per channel*/
      for(i = 0; i < numpixels; i++)
      {
        unsigned value = readBitsFromReversedStream(&bp, in, infoIn->bitDepth);
        if(OUT_ALPHA) out[OUT_BYTES * i + 1] = 255;
        if(OUT_ALPHA && infoIn->key_defined && value && ((1U << infoIn->bitDepth) - 1U) == infoIn->key_r && ((1U << infoIn->bitDepth) - 1U)) out[OUT_BYTES * i + 1] = 0;
        value = (value * 255) / ((1 << infoIn->bitDepth) - 1); /*scale value from 0 to 255*/
        out[OUT_BYTES * i] = (unsigned char)(value);
      }
    }
  }
  else return 59;

  return 0;
}

/*Path predictor, used by PNG filter type 4*/
static int paethPredictor(int a, int b, int c)
{
  int p = a + b - c;
  int pa = p > a ? p - a : a - p;
  int pb = p > b ? p - b : b - p;
  int pc = p > c ? p - c : c - p;

  if(pa <= pb && pa <= pc) return a;
  else if(pb <= pc) return b;
  else return c;
}

/*shared values used by multiple Adam7 related functions*/

static const unsigned ADAM7_IX[7] = { 0, 4, 0, 2, 0, 1, 0 }; /*x start values*/
static const unsigned ADAM7_IY[7] = { 0, 0, 4, 0, 2, 0, 1 }; /*y start values*/
static const unsigned ADAM7_DX[7] = { 8, 8, 4, 4, 2, 2, 1 }; /*x delta values*/
static const unsigned ADAM7_DY[7] = { 8, 8, 8, 4, 4, 2, 2 }; /*y delta values*/

static void Adam7_getpassvalues(unsigned passw[7], unsigned passh[7], size_t filter_passstart[8], size_t padded_passstart[8], size_t passstart[8], unsigned w, unsigned h, unsigned bpp)
{
  /*the passstart values have 8 values: the 8th one actually indicates the byte after the end of the 7th (= last) pass*/
  unsigned i;

  /*calculate width and height in pixels of each pass*/
  for(i = 0; i < 7; i++)
  {
    passw[i] = (w + ADAM7_DX[i] - ADAM7_IX[i] - 1) / ADAM7_DX[i];
    passh[i] = (h + ADAM7_DY[i] - ADAM7_IY[i] - 1) / ADAM7_DY[i];
    if(passw[i] == 0) passh[i] = 0;
    if(passh[i] == 0) passw[i] = 0;
  }

  filter_passstart[0] = padded_passstart[0] = passstart[0] = 0;
  for(i = 0; i < 7; i++)
  {
    filter_passstart[i + 1] = filter_passstart[i] + ((passw[i] && passh[i]) ? passh[i] * (1 + (passw[i] * bpp + 7) / 8) : 0); /*if passw[i] is 0, it's 0 bytes, not 1 (no filtertype-byte)*/
    padded_passstart[i + 1] = padded_passstart[i] + passh[i] * ((passw[i] * bpp + 7) / 8); /*bits padded if needed to fill full byte at end of each scanline*/
    passstart[i + 1] = passstart[i] + (passh[i] * passw[i] * bpp + 7) / 8; /*only padded at end of reduced image*/
  }
}


/* ////////////////////////////////////////////////////////////////////////// */
/* / PNG Encoder                                                            / */
/* ////////////////////////////////////////////////////////////////////////// */

/*chunkName must be string of 4 characters*/
static unsigned addChunk(ucvector* out, const char* chunkName, const unsigned char* data, size_t length)
{
  unsigned error = LodePNG_create_chunk(&out->data, &out->size, (unsigned)length, chunkName, data);
  if(error) return error;
  out->allocsize = out->size; /*fix the allocsize again*/
  return 0;
}

static void writeSignature(ucvector* out)
{
  /*8 bytes PNG signature*/
  ucvector_push_back(out, 137);
  ucvector_push_back(out, 80);
  ucvector_push_back(out, 78);
  ucvector_push_back(out, 71);
  ucvector_push_back(out, 13);
  ucvector_push_back(out, 10);
  ucvector_push_back(out, 26);
  ucvector_push_back(out, 10);
}

static unsigned addChunk_IHDR(ucvector* out, unsigned w, unsigned h, unsigned bitDepth, unsigned colorType, unsigned interlaceMethod)
{
  unsigned error = 0;
  ucvector header;
  ucvector_init(&header);

  LodePNG_add32bitInt(&header, w); /*width*/
  LodePNG_add32bitInt(&header, h); /*height*/
  ucvector_push_back(&header, (unsigned char)bitDepth); /*bit depth*/
  ucvector_push_back(&header, (unsigned char)colorType); /*color type*/
  ucvector_push_back(&header, 0); /*compression method*/
  ucvector_push_back(&header, 0); /*filter method*/
  ucvector_push_back(&header, interlaceMethod); /*interlace method*/

  error = addChunk(out, "IHDR", header.data, header.size);
  ucvector_cleanup(&header);

  return error;
}

static unsigned addChunk_PLTE(ucvector* out, const LodePNG_InfoColor* info)
{
  unsigned error = 0;
  size_t i;
  ucvector PLTE;
  ucvector_init(&PLTE);
  for(i = 0; i < info->palettesize * 4; i++) if(i % 4 != 3) ucvector_push_back(&PLTE, info->palette[i]); /*add all channels except alpha channel*/
  error = addChunk(out, "PLTE", PLTE.data, PLTE.size);
  ucvector_cleanup(&PLTE);

  return error;
}

static unsigned addChunk_tRNS(ucvector* out, const LodePNG_InfoColor* info)
{
  unsigned error = 0;
  size_t i;
  ucvector tRNS;
  ucvector_init(&tRNS);
  if(info->colorType == 3)
  {
    for(i = 0; i < info->palettesize; i++) ucvector_push_back(&tRNS, info->palette[4 * i + 3]); /*add only alpha channel*/
  }
  else if(info->colorType == 0)
  {
    if(info->key_defined)
    {
      ucvector_push_back(&tRNS, (unsigned char)(info->key_r / 256));
      ucvector_push_back(&tRNS, (unsigned char)(info->key_r % 256));
    }
  }
  else if(info->colorType == 2)
  {
    if(info->key_defined)
    {
      ucvector_push_back(&tRNS, (unsigned char)(info->key_r / 256));
      ucvector_push_back(&tRNS, (unsigned char)(info->key_r % 256));
      ucvector_push_back(&tRNS, (unsigned char)(info->key_g / 256));
      ucvector_push_back(&tRNS, (unsigned char)(info->key_g % 256));
      ucvector_push_back(&tRNS, (unsigned char)(info->key_b / 256));
      ucvector_push_back(&tRNS, (unsigned char)(info->key_b % 256));
    }
  }

  error = addChunk(out, "tRNS", tRNS.data, tRNS.size);
  ucvector_cleanup(&tRNS);

  return error;
}

static unsigned addChunk_IDAT(ucvector* out, const unsigned char* data, size_t datasize, LodeZlib_DeflateSettings* zlibsettings)
{
  ucvector zlibdata;
  unsigned error = 0;

  /*compress with the Zlib compressor*/
  ucvector_init(&zlibdata);
  error = LodePNG_compress(&zlibdata.data, &zlibdata.size, data, datasize, zlibsettings);
  if(!error) error = addChunk(out, "IDAT", zlibdata.data, zlibdata.size);
  ucvector_cleanup(&zlibdata);

  return error;
}

static unsigned addChunk_IEND(ucvector* out)
{
  unsigned error = 0;
  error = addChunk(out, "IEND", 0, 0);
  return error;
}

static void filterScanline(unsigned char* out, const unsigned char* scanline, const unsigned char* prevline, size_t length, size_t bytewidth, unsigned char filterType)
{
  size_t i;
  switch(filterType)
  {
    case 0:
      for(i = 0; i < length; i++) out[i] = scanline[i];
      break;
    case 1:
      for(i =         0; i < bytewidth; i++) out[i] = scanline[i];
      for(i = bytewidth; i <    length; i++) out[i] = scanline[i] - scanline[i - bytewidth];
      break;
    case 2:
      if(prevline) for(i = 0; i < length; i++) out[i] = scanline[i] - prevline[i];
      else         for(i = 0; i < length; i++) out[i] = scanline[i];
      break;
    case 3:
      if(prevline)
      {
        for(i =         0; i < bytewidth; i++) out[i] = scanline[i] - prevline[i] / 2;
        for(i = bytewidth; i <    length; i++) out[i] = scanline[i] - ((scanline[i - bytewidth] + prevline[i]) / 2);
      }
      else
      {
        for(i =         0; i < length; i++) out[i] = scanline[i];
        for(i = bytewidth; i < length; i++) out[i] = scanline[i] - scanline[i - bytewidth] / 2;
      }
      break;
    case 4:
      if(prevline)
      {
        for(i =         0; i < bytewidth; i++) out[i] = (unsigned char)(scanline[i] - paethPredictor(0, prevline[i], 0));
        for(i = bytewidth; i <    length; i++) out[i] = (unsigned char)(scanline[i] - paethPredictor(scanline[i - bytewidth], prevline[i], prevline[i - bytewidth]));
      }
      else
      {
        for(i =         0; i < bytewidth; i++) out[i] = scanline[i];
        for(i = bytewidth; i <    length; i++) out[i] = (unsigned char)(scanline[i] - paethPredictor(scanline[i - bytewidth], 0, 0));
      }
      break;
  default: return; /*unexisting filter type given*/
  }
}

static unsigned filter(unsigned char* out, const unsigned char* in, unsigned w, unsigned h, const LodePNG_InfoColor* info)
{
  /*
  For PNG filter method 0
  out must be a buffer with as size: h + (w * h * bpp + 7) / 8, because there are the scanlines with 1 extra byte per scanline

  There is a nice heuristic described here: http://www.cs.toronto.edu/~cosmin/pngtech/optipng.html. It says:
   *  If the image type is Palette, or the bit depth is smaller than 8, then do not filter the image (i.e. use fixed filtering, with the filter None).
   * (The other case) If the image type is Grayscale or RGB (with or without Alpha), and the bit depth is not smaller than 8, then use adaptive filtering heuristic as follows: independently for each row, apply all five filters and select the filter that produces the smallest sum of absolute values per row.

  Here the above method is used mostly. Note though that it appears to be better to use the adaptive filtering on the plasma 8-bit palette example, but that image isn't the best reference for palette images in general.
  */

  unsigned bpp = LodePNG_InfoColor_getBpp(info);
  size_t linebytes = (w * bpp + 7) / 8; /*the width of a scanline in bytes, not including the filter type*/
  size_t bytewidth = (bpp + 7) / 8; /*bytewidth is used for filtering, is 1 when bpp < 8, number of bytes per pixel otherwise*/
  const unsigned char* prevline = 0;
  unsigned x, y;
  unsigned heuristic;
  unsigned error = 0;

  if(bpp == 0) return 31; /*invalid color type*/

  /*choose heuristic as described above*/
  if(info->colorType == 3 || info->bitDepth < 8) heuristic = 0;
  else heuristic = 1;

  if(heuristic == 0) /*None filtertype for everything*/
  {
    for(y = 0; y < h; y++)
    {
      size_t outindex = (1 + linebytes) * y; /*the extra filterbyte added to each row*/
      size_t inindex = linebytes * y;
      const unsigned TYPE = 0;
      out[outindex] = TYPE; /*filter type byte*/
      filterScanline(&out[outindex + 1], &in[inindex], prevline, linebytes, bytewidth, TYPE);
      prevline = &in[inindex];
    }
  }
  else if(heuristic == 1) /*adaptive filtering*/
  {
    size_t sum[5];
    ucvector attempt[5]; /*five filtering attempts, one for each filter type*/
    size_t smallest = 0;
    unsigned type, bestType = 0;

    for(type = 0; type < 5; type++) ucvector_init(&attempt[type]);
    for(type = 0; type < 5; type++)
    {
      if(!ucvector_resize(&attempt[type], linebytes)) { error = 9949; break; }
    }

    if(!error)
    {
      for(y = 0; y < h; y++)
      {
        /*try the 5 filter types*/
        for(type = 0; type < 5; type++)
        {
          filterScanline(attempt[type].data, &in[y * linebytes], prevline, linebytes, bytewidth, type);

          /*calculate the sum of the result*/
          sum[type] = 0;
          for(x = 0; x < attempt[type].size; x+=3) sum[type] += attempt[type].data[x]; /*note that not all pixels are checked to speed this up while still having probably the best choice*/

          /*check if this is smallest sum (or if type == 0 it's the first case so always store the values)*/
          if(type == 0 || sum[type] < smallest)
          {
            bestType = type;
            smallest = sum[type];
          }
        }

        prevline = &in[y * linebytes];

        /*now fill the out values*/
        out[y * (linebytes + 1)] = bestType; /*the first byte of a scanline will be the filter type*/
        for(x = 0; x < linebytes; x++) out[y * (linebytes + 1) + 1 + x] = attempt[bestType].data[x];
      }
    }

    for(type = 0; type < 5; type++) ucvector_cleanup(&attempt[type]);
  }

  return error;
}

static void addPaddingBits(unsigned char* out, const unsigned char* in, size_t olinebits, size_t ilinebits, unsigned h)
{
  /*The opposite of the removePaddingBits function
  olinebits must be >= ilinebits*/
  unsigned y;
  size_t diff = olinebits - ilinebits;
  size_t obp = 0, ibp = 0; /*bit pointers*/
  for(y = 0; y < h; y++)
  {
    size_t x;
    for(x = 0; x < ilinebits; x++)
    {
      unsigned char bit = readBitFromReversedStream(&ibp, in);
      setBitOfReversedStream(&obp, out, bit);
    }
    /*obp += diff; --> no, fill in some value in the padding bits too, to avoid "Use of uninitialised value of size ###" warning from valgrind*/
    for(x = 0; x < diff; x++) setBitOfReversedStream(&obp, out, 0);
  }
}

static void Adam7_interlace(unsigned char* out, const unsigned char* in, unsigned w, unsigned h, unsigned bpp)
{
  /*Note: this function works on image buffers WITHOUT padding bits at end of scanlines with non-multiple-of-8 bit amounts, only between reduced images is padding*/
  unsigned passw[7], passh[7]; size_t filter_passstart[8], padded_passstart[8], passstart[8];
  unsigned i;

  Adam7_getpassvalues(passw, passh, filter_passstart, padded_passstart, passstart, w, h, bpp);

  if(bpp >= 8)
  {
    for(i = 0; i < 7; i++)
    {
      unsigned x, y, b;
      size_t bytewidth = bpp / 8;
      for(y = 0; y < passh[i]; y++)
      for(x = 0; x < passw[i]; x++)
      {
        size_t pixelinstart = ((ADAM7_IY[i] + y * ADAM7_DY[i]) * w + ADAM7_IX[i] + x * ADAM7_DX[i]) * bytewidth;
        size_t pixeloutstart = passstart[i] + (y * passw[i] + x) * bytewidth;
        for(b = 0; b < bytewidth; b++)
        {
          out[pixeloutstart + b] = in[pixelinstart + b];
        }
      }
    }
  }
  else /*bpp < 8: Adam7 with pixels < 8 bit is a bit trickier: with bit pointers*/
  {
    for(i = 0; i < 7; i++)
    {
      unsigned x, y, b;
      unsigned ilinebits = bpp * passw[i];
      unsigned olinebits = bpp * w;
      size_t obp, ibp; /*bit pointers (for out and in buffer)*/
      for(y = 0; y < passh[i]; y++)
      for(x = 0; x < passw[i]; x++)
      {
        ibp = (ADAM7_IY[i] + y * ADAM7_DY[i]) * olinebits + (ADAM7_IX[i] + x * ADAM7_DX[i]) * bpp;
        obp = (8 * passstart[i]) + (y * ilinebits + x * bpp);
        for(b = 0; b < bpp; b++)
        {
          unsigned char bit = readBitFromReversedStream(&ibp, in);
          setBitOfReversedStream(&obp, out, bit);
        }
      }
    }
  }
}

/*out must be buffer big enough to contain uncompressed IDAT chunk data, and in must contain the full image*/
static unsigned preProcessScanlines(unsigned char** out, size_t* outsize, const unsigned char* in, const LodePNG_InfoPng* infoPng) /*return value is error*/
{
  /*
  This function converts the pure 2D image with the PNG's colortype, into filtered-padded-interlaced data. Steps:
  *) if no Adam7: 1) add padding bits (= possible extra bits per scanline if bpp < 8) 2) filter
  *) if adam7: 1) Adam7_interlace 2) 7x add padding bits 3) 7x filter
  */
  unsigned bpp = LodePNG_InfoColor_getBpp(&infoPng->color);
  unsigned w = infoPng->width;
  unsigned h = infoPng->height;
  unsigned error = 0;

  if(infoPng->interlaceMethod == 0)
  {
    *outsize = h + (h * ((w * bpp + 7) / 8)); /*image size plus an extra byte per scanline + possible padding bits*/
    *out = (unsigned char*)malloc(*outsize);
    if(!(*out) && (*outsize)) error = 9950;

    if(!error)
    {
      if(bpp < 8 && w * bpp != ((w * bpp + 7) / 8) * 8) /*non multiple of 8 bits per scanline, padding bits needed per scanline*/
      {
        ucvector padded;
        ucvector_init(&padded);
        if(!ucvector_resize(&padded, h * ((w * bpp + 7) / 8))) error = 9951;
        if(!error)
        {
          addPaddingBits(padded.data, in, ((w * bpp + 7) / 8) * 8, w * bpp, h);
          error = filter(*out, padded.data, w, h, &infoPng->color);
        }
        ucvector_cleanup(&padded);
      }
      else error = filter(*out, in, w, h, &infoPng->color); /*we can immediately filter into the out buffer, no other steps needed*/
    }
  }
  else /*interlaceMethod is 1 (Adam7)*/
  {
    unsigned char* adam7 = (unsigned char*)malloc((h * w * bpp + 7) / 8);
    if(!adam7 && ((h * w * bpp + 7) / 8)) error = 9952; /*malloc failed*/

    while(!error) /*not a real while loop, used to break out to cleanup to avoid a goto*/
    {
      unsigned passw[7], passh[7]; size_t filter_passstart[8], padded_passstart[8], passstart[8];
      unsigned i;

      Adam7_getpassvalues(passw, passh, filter_passstart, padded_passstart, passstart, w, h, bpp);

      *outsize = filter_passstart[7]; /*image size plus an extra byte per scanline + possible padding bits*/
      *out = (unsigned char*)malloc(*outsize);
      if(!(*out) && (*outsize)) { error = 9953; break; }

      Adam7_interlace(adam7, in, w, h, bpp);

      for(i = 0; i < 7; i++)
      {
        if(bpp < 8)
        {
          ucvector padded;
          ucvector_init(&padded);
          if(!ucvector_resize(&padded, h * ((w * bpp + 7) / 8))) error = 9954;
          if(!error)
          {
            addPaddingBits(&padded.data[padded_passstart[i]], &adam7[passstart[i]], ((passw[i] * bpp + 7) / 8) * 8, passw[i] * bpp, passh[i]);
            error = filter(&(*out)[filter_passstart[i]], &padded.data[padded_passstart[i]], passw[i], passh[i], &infoPng->color);
          }

          ucvector_cleanup(&padded);
        }
        else
        {
          error = filter(&(*out)[filter_passstart[i]], &adam7[padded_passstart[i]], passw[i], passh[i], &infoPng->color);
        }
      }

      break;
    }

    free(adam7);
  }

  return error;
}

/*palette must have 4 * palettesize bytes allocated*/
static unsigned isPaletteFullyOpaque(const unsigned char* palette, size_t palettesize) /*palette given in format RGBARGBARGBARGBA...*/
{
  size_t i;
  for(i = 0; i < palettesize; i++)
  {
    if(palette[4 * i + 3] != 255) return 0;
  }
  return 1;
}

/*this function checks if the input image given by the user has no transparent pixels*/
static unsigned isFullyOpaque(const unsigned char* image, unsigned w, unsigned h, const LodePNG_InfoColor* info)
{
  /*TODO: When the user specified a color key for the input image, then this function must also check for pixels that are the same as the color key and treat those as transparent.*/

  unsigned i, numpixels = w * h;
  if(info->colorType == 6)
  {
    if(info->bitDepth == 8)
    {
      for(i = 0; i < numpixels; i++) if(image[i * 4 + 3] != 255) return 0;
    }
    else
    {
      for(i = 0; i < numpixels; i++) if(image[i * 8 + 6] != 255 || image[i * 8 + 7] != 255) return 0;
    }
    return 1; /*no single pixel with alpha channel other than 255 found*/
  }
  else if(info->colorType == 4)
  {
    if(info->bitDepth == 8)
    {
      for(i = 0; i < numpixels; i++) if(image[i * 2 + 1] != 255) return 0;
    }
    else
    {
      for(i = 0; i < numpixels; i++) if(image[i * 4 + 2] != 255 || image[i * 4 + 3] != 255) return 0;
    }
    return 1; /*no single pixel with alpha channel other than 255 found*/
  }
  else if(info->colorType == 3)
  {
    /*when there's a palette, we could check every pixel for translucency, but much quicker is to just check the palette*/
    return(isPaletteFullyOpaque(info->palette, info->palettesize));
  }

  return 0; /*color type that isn't supported by this function yet, so assume there is transparency to be safe*/
}

void LodePNG_encode(LodePNG_Encoder* encoder, unsigned char** out, size_t* outsize, const unsigned char* image, unsigned w, unsigned h)
{
  LodePNG_InfoPng info;
  ucvector outv;
  unsigned char* data = 0; /*uncompressed version of the IDAT chunk data*/
  size_t datasize = 0;

  /*provide some proper output values if error will happen*/
  *out = 0;
  *outsize = 0;
  encoder->error = 0;

  info = encoder->infoPng; /*UNSAFE copy to avoid having to cleanup! but we will only change primitive parameters, and not invoke the cleanup function nor touch the palette's buffer so we use it safely*/
  info.width = w;
  info.height = h;

  if(encoder->settings.autoLeaveOutAlphaChannel && isFullyOpaque(image, w, h, &encoder->infoRaw.color))
  {
    /*go to a color type without alpha channel*/
    if(info.color.colorType == 6) info.color.colorType = 2;
    else if(info.color.colorType == 4) info.color.colorType = 0;
  }

  if(encoder->settings.zlibsettings.windowSize > 32768) { encoder->error = 60; return; } /*error: windowsize larger than allowed*/
  if(encoder->settings.zlibsettings.btype > 2) { encoder->error = 61; return; } /*error: unexisting btype*/
  if(encoder->infoPng.interlaceMethod > 1) { encoder->error = 71; return; } /*error: unexisting interlace mode*/
  if((encoder->error = checkColorValidity(info.color.colorType, info.color.bitDepth))) return; /*error: unexisting color type given*/
  if((encoder->error = checkColorValidity(encoder->infoRaw.color.colorType, encoder->infoRaw.color.bitDepth))) return; /*error: unexisting color type given*/

  if(!LodePNG_InfoColor_equal(&encoder->infoRaw.color, &info.color))
  {
    unsigned char* converted;
    size_t size = (w * h * LodePNG_InfoColor_getBpp(&info.color) + 7) / 8;

    if((info.color.colorType != 6 && info.color.colorType != 2) || (info.color.bitDepth != 8)) { encoder->error = 59; return; } /*for the output image, only these types are supported*/
    converted = (unsigned char*)malloc(size);
    if(!converted && size) encoder->error = 9955; /*error: malloc failed*/
    if(!encoder->error) encoder->error = LodePNG_convert(converted, image, &info.color, &encoder->infoRaw.color, w, h);
    if(!encoder->error) preProcessScanlines(&data, &datasize, converted, &info);/*filter(data.data, converted.data, w, h, LodePNG_InfoColor_getBpp(&info.color));*/
    free(converted);
  }
  else preProcessScanlines(&data, &datasize, image, &info);/*filter(data.data, image, w, h, LodePNG_InfoColor_getBpp(&info.color));*/

  ucvector_init(&outv);
  while(!encoder->error) /*not really a while loop, this is only used to break out if an error happens to avoid goto's to do the ucvector cleanup*/
  {
    /*write signature and chunks*/
    writeSignature(&outv);
    /*IHDR*/
    addChunk_IHDR(&outv, w, h, info.color.bitDepth, info.color.colorType, info.interlaceMethod);
    /*PLTE*/
    if(info.color.colorType == 3)
    {
      if(info.color.palettesize == 0 || info.color.palettesize > 256) { encoder->error = 68; break; }
      addChunk_PLTE(&outv, &info.color);
    }
    if(encoder->settings.force_palette && (info.color.colorType == 2 || info.color.colorType == 6))
    {
      if(info.color.palettesize == 0 || info.color.palettesize > 256) { encoder->error = 68; break; }
      addChunk_PLTE(&outv, &info.color);
    }
    /*tRNS*/
    if(info.color.colorType == 3 && !isPaletteFullyOpaque(info.color.palette, info.color.palettesize)) addChunk_tRNS(&outv, &info.color);
    if((info.color.colorType == 0 || info.color.colorType == 2) && info.color.key_defined) addChunk_tRNS(&outv, &info.color);
    /*IDAT (multiple IDAT chunks must be consecutive)*/
    encoder->error = addChunk_IDAT(&outv, data, datasize, &encoder->settings.zlibsettings);
    if(encoder->error) break;
    /*IEND*/
    addChunk_IEND(&outv);

    break; /*this isn't really a while loop; no error happened so break out now!*/
  }

  free(data);
  /*instead of cleaning the vector up, give it to the output*/
  *out = outv.data;
  *outsize = outv.size;
}

void LodePNG_EncodeSettings_init(LodePNG_EncodeSettings* settings)
{
  LodeZlib_DeflateSettings_init(&settings->zlibsettings);
  settings->autoLeaveOutAlphaChannel = 1;
  settings->force_palette = 0;
}

void LodePNG_Encoder_init(LodePNG_Encoder* encoder)
{
  LodePNG_EncodeSettings_init(&encoder->settings);
  LodePNG_InfoPng_init(&encoder->infoPng);
  LodePNG_InfoRaw_init(&encoder->infoRaw);
  encoder->error = 1;
}

void LodePNG_Encoder_cleanup(LodePNG_Encoder* encoder)
{
  LodePNG_InfoPng_cleanup(&encoder->infoPng);
  LodePNG_InfoRaw_cleanup(&encoder->infoRaw);
}

void LodePNG_Encoder_copy(LodePNG_Encoder* dest, const LodePNG_Encoder* source)
{
  LodePNG_Encoder_cleanup(dest);
  *dest = *source;
  LodePNG_InfoPng_init(&dest->infoPng);
  LodePNG_InfoRaw_init(&dest->infoRaw);
  dest->error = LodePNG_InfoPng_copy(&dest->infoPng, &source->infoPng); if(dest->error) return;
  dest->error = LodePNG_InfoRaw_copy(&dest->infoRaw, &source->infoRaw); if(dest->error) return;
}

/* ////////////////////////////////////////////////////////////////////////// */
/* / File IO                                                                / */
/* ////////////////////////////////////////////////////////////////////////// */

/*write given buffer to the file, overwriting the file, it doesn't append to it.*/
unsigned LodePNG_saveFile(const unsigned char* buffer, size_t buffersize, const char* filename)
{
  FILE* file = fopen(filename,"wb");
  if(!file) return 79;
  fwrite((char*)buffer , 1 , buffersize, file);
  fclose(file);
  return 0;
}