summaryrefslogtreecommitdiff
path: root/lodepng.c
blob: 6568bba8cb9739b597e3b4b93b7ed3940e36d26e (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054
2055
2056
2057
2058
2059
2060
2061
2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095
2096
2097
2098
2099
2100
2101
2102
2103
2104
2105
2106
2107
2108
2109
2110
2111
2112
2113
2114
2115
2116
2117
2118
2119
2120
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
2133
2134
2135
2136
2137
2138
2139
2140
2141
2142
2143
2144
2145
2146
2147
2148
2149
2150
2151
2152
2153
2154
2155
2156
2157
2158
2159
2160
2161
2162
2163
2164
2165
2166
2167
2168
2169
2170
2171
2172
2173
2174
2175
2176
2177
2178
2179
2180
2181
2182
2183
2184
2185
2186
2187
2188
2189
2190
2191
2192
2193
2194
2195
2196
2197
2198
2199
2200
2201
2202
2203
2204
2205
2206
2207
2208
2209
2210
2211
2212
2213
2214
2215
2216
2217
2218
2219
2220
2221
2222
2223
2224
2225
2226
2227
2228
2229
2230
2231
2232
2233
2234
2235
2236
2237
2238
2239
2240
2241
2242
2243
2244
2245
2246
2247
2248
2249
2250
2251
2252
2253
2254
2255
2256
2257
2258
2259
2260
2261
2262
2263
2264
2265
2266
2267
2268
2269
2270
2271
2272
2273
2274
2275
2276
2277
2278
2279
2280
2281
2282
2283
2284
2285
2286
2287
2288
2289
2290
2291
2292
2293
2294
2295
2296
2297
2298
2299
2300
2301
2302
2303
2304
2305
2306
2307
2308
2309
2310
2311
2312
2313
2314
2315
2316
2317
2318
2319
2320
2321
2322
2323
2324
2325
2326
2327
2328
2329
2330
2331
2332
2333
2334
2335
2336
2337
2338
2339
2340
2341
2342
2343
2344
2345
2346
2347
2348
2349
2350
2351
2352
2353
2354
2355
2356
2357
2358
2359
2360
2361
2362
2363
2364
2365
2366
2367
2368
2369
2370
2371
2372
2373
2374
2375
2376
2377
2378
2379
2380
2381
2382
2383
2384
2385
2386
2387
2388
2389
2390
2391
2392
2393
2394
2395
2396
2397
2398
2399
2400
2401
2402
2403
2404
2405
2406
2407
2408
2409
2410
2411
2412
2413
2414
2415
2416
2417
2418
2419
2420
2421
2422
2423
2424
2425
2426
2427
2428
2429
2430
2431
2432
2433
2434
2435
2436
2437
2438
2439
2440
2441
2442
2443
2444
2445
2446
2447
2448
2449
2450
2451
2452
2453
2454
2455
2456
2457
2458
2459
2460
2461
2462
2463
2464
2465
2466
2467
2468
2469
2470
2471
2472
2473
2474
2475
2476
2477
2478
2479
2480
2481
2482
2483
2484
2485
2486
2487
2488
2489
2490
2491
2492
2493
2494
2495
2496
2497
2498
2499
2500
2501
2502
2503
2504
2505
2506
2507
2508
2509
2510
2511
2512
2513
2514
2515
2516
2517
2518
2519
2520
2521
2522
2523
2524
2525
2526
2527
2528
2529
2530
2531
2532
2533
2534
2535
2536
2537
2538
2539
2540
2541
2542
2543
2544
2545
2546
2547
2548
2549
2550
2551
2552
2553
2554
2555
2556
2557
2558
2559
2560
2561
2562
2563
2564
2565
2566
2567
2568
2569
2570
2571
2572
2573
2574
2575
2576
2577
2578
2579
2580
2581
2582
2583
2584
2585
2586
2587
2588
2589
2590
2591
2592
2593
2594
2595
2596
2597
2598
2599
2600
2601
2602
2603
2604
2605
2606
2607
2608
2609
2610
2611
2612
2613
2614
2615
2616
2617
2618
2619
2620
2621
2622
2623
2624
2625
2626
2627
2628
2629
2630
2631
2632
2633
2634
2635
2636
2637
2638
2639
2640
2641
2642
2643
2644
2645
2646
2647
2648
2649
2650
2651
2652
2653
2654
2655
2656
2657
2658
2659
2660
2661
2662
2663
2664
2665
2666
2667
2668
2669
2670
2671
2672
2673
2674
2675
2676
2677
2678
2679
2680
2681
2682
2683
2684
2685
2686
2687
2688
2689
2690
2691
2692
2693
2694
2695
2696
2697
2698
2699
2700
2701
2702
2703
2704
2705
2706
2707
2708
2709
2710
2711
2712
2713
2714
2715
2716
2717
2718
2719
2720
2721
2722
2723
2724
2725
2726
2727
2728
2729
2730
2731
2732
2733
2734
2735
2736
2737
2738
2739
2740
2741
2742
2743
2744
2745
2746
2747
2748
2749
2750
2751
2752
2753
2754
2755
2756
2757
2758
2759
2760
2761
2762
2763
2764
2765
2766
2767
2768
2769
2770
2771
2772
2773
2774
2775
2776
2777
2778
2779
2780
2781
2782
2783
2784
2785
2786
2787
2788
2789
2790
2791
2792
2793
2794
2795
2796
2797
2798
2799
2800
2801
2802
2803
2804
2805
2806
2807
2808
2809
2810
2811
2812
2813
2814
2815
2816
2817
2818
2819
2820
2821
2822
2823
2824
2825
2826
2827
2828
2829
2830
2831
2832
2833
2834
2835
2836
2837
2838
2839
2840
2841
2842
2843
2844
2845
2846
2847
2848
2849
2850
2851
2852
2853
2854
2855
2856
2857
2858
2859
2860
2861
2862
2863
2864
2865
2866
2867
2868
2869
2870
2871
2872
2873
2874
2875
2876
2877
2878
2879
2880
2881
2882
2883
2884
2885
2886
2887
2888
2889
2890
2891
2892
2893
2894
2895
2896
2897
2898
2899
2900
2901
2902
2903
2904
2905
2906
2907
2908
2909
2910
2911
2912
2913
2914
2915
2916
2917
2918
2919
2920
2921
2922
2923
2924
2925
2926
2927
2928
2929
2930
2931
2932
2933
2934
2935
2936
2937
2938
2939
2940
2941
2942
2943
2944
2945
2946
2947
2948
2949
2950
2951
2952
2953
2954
2955
2956
2957
2958
2959
2960
2961
2962
2963
2964
2965
2966
2967
2968
2969
2970
2971
2972
2973
2974
2975
2976
2977
2978
2979
2980
2981
2982
2983
2984
2985
2986
2987
2988
2989
2990
2991
2992
2993
2994
2995
2996
2997
2998
2999
3000
3001
3002
3003
3004
3005
3006
3007
3008
3009
3010
3011
3012
3013
3014
3015
3016
3017
3018
3019
3020
3021
3022
3023
3024
3025
3026
3027
3028
3029
3030
3031
3032
3033
3034
3035
3036
3037
3038
3039
3040
3041
3042
3043
3044
3045
3046
3047
3048
3049
3050
3051
3052
3053
3054
3055
3056
3057
3058
3059
3060
3061
3062
3063
3064
3065
3066
3067
3068
3069
3070
3071
3072
3073
3074
3075
3076
3077
3078
3079
3080
3081
3082
3083
3084
3085
3086
3087
3088
3089
3090
3091
3092
3093
3094
3095
3096
3097
3098
3099
3100
3101
3102
3103
3104
3105
3106
3107
3108
3109
3110
3111
3112
3113
3114
3115
3116
3117
3118
3119
3120
3121
3122
3123
3124
3125
3126
3127
3128
3129
3130
3131
3132
3133
3134
3135
3136
3137
3138
3139
3140
3141
3142
3143
3144
3145
3146
3147
3148
3149
3150
3151
3152
3153
3154
3155
3156
3157
3158
3159
3160
3161
3162
3163
3164
3165
3166
3167
3168
3169
3170
3171
3172
3173
3174
3175
3176
3177
3178
3179
3180
3181
3182
3183
3184
3185
3186
3187
3188
3189
3190
3191
3192
3193
3194
3195
3196
3197
3198
3199
3200
3201
3202
3203
3204
3205
3206
3207
3208
3209
3210
3211
3212
3213
3214
3215
3216
3217
3218
3219
3220
3221
3222
3223
3224
3225
3226
3227
3228
3229
3230
3231
3232
3233
3234
3235
3236
3237
3238
3239
3240
3241
3242
3243
3244
3245
3246
3247
3248
3249
3250
3251
3252
3253
3254
3255
3256
3257
3258
3259
3260
3261
3262
3263
3264
3265
3266
3267
3268
3269
3270
3271
3272
3273
3274
3275
3276
3277
3278
3279
3280
3281
3282
3283
3284
3285
3286
3287
3288
3289
3290
3291
3292
3293
3294
3295
3296
3297
3298
3299
3300
3301
3302
3303
3304
3305
3306
3307
3308
3309
3310
3311
3312
3313
3314
3315
3316
3317
3318
3319
3320
3321
3322
3323
3324
3325
3326
3327
3328
3329
3330
3331
3332
3333
3334
3335
3336
3337
3338
3339
3340
3341
3342
3343
3344
3345
3346
3347
3348
3349
3350
3351
3352
3353
3354
3355
3356
3357
3358
3359
3360
3361
3362
3363
3364
3365
3366
3367
3368
3369
3370
3371
3372
3373
3374
3375
3376
3377
3378
3379
3380
3381
3382
3383
3384
3385
3386
3387
3388
3389
3390
3391
3392
3393
3394
3395
3396
3397
3398
3399
3400
3401
3402
3403
3404
3405
3406
3407
3408
3409
3410
3411
3412
3413
3414
3415
3416
3417
3418
3419
3420
3421
3422
3423
3424
3425
3426
3427
3428
3429
3430
3431
3432
3433
3434
3435
3436
3437
3438
3439
3440
3441
3442
3443
3444
3445
3446
3447
3448
3449
3450
3451
3452
3453
3454
3455
3456
3457
3458
3459
3460
3461
3462
3463
3464
3465
3466
3467
3468
3469
3470
3471
3472
3473
3474
3475
3476
3477
3478
3479
3480
3481
3482
3483
3484
3485
3486
3487
3488
3489
3490
3491
3492
3493
3494
3495
3496
3497
3498
3499
3500
3501
3502
3503
3504
3505
3506
3507
3508
3509
3510
3511
3512
3513
3514
3515
3516
3517
3518
3519
3520
3521
3522
3523
3524
3525
3526
3527
3528
3529
3530
3531
3532
3533
3534
3535
3536
3537
3538
3539
3540
3541
3542
3543
3544
3545
3546
3547
3548
3549
3550
3551
3552
3553
3554
3555
3556
3557
3558
3559
3560
3561
3562
3563
3564
3565
3566
3567
3568
3569
3570
3571
3572
3573
3574
3575
3576
3577
3578
3579
3580
3581
3582
3583
3584
3585
3586
3587
3588
3589
3590
3591
3592
3593
3594
3595
3596
3597
3598
3599
3600
3601
3602
3603
3604
3605
3606
3607
3608
3609
3610
3611
3612
3613
3614
3615
3616
3617
3618
3619
3620
3621
3622
3623
3624
3625
3626
3627
3628
3629
3630
3631
3632
3633
3634
3635
3636
3637
3638
3639
3640
3641
3642
3643
3644
3645
3646
3647
3648
3649
3650
3651
3652
3653
3654
3655
3656
3657
3658
3659
3660
3661
3662
3663
3664
3665
3666
3667
3668
3669
3670
3671
3672
3673
3674
3675
3676
3677
3678
3679
3680
3681
3682
3683
3684
3685
3686
3687
3688
3689
3690
3691
3692
3693
3694
3695
3696
3697
3698
3699
3700
3701
3702
3703
3704
3705
3706
3707
3708
3709
3710
3711
3712
3713
3714
3715
3716
3717
3718
3719
3720
3721
3722
3723
3724
3725
3726
3727
3728
3729
3730
3731
3732
3733
3734
3735
3736
3737
3738
3739
3740
3741
3742
3743
3744
3745
3746
3747
3748
3749
3750
3751
3752
3753
3754
3755
3756
3757
3758
3759
3760
3761
3762
3763
3764
3765
3766
3767
3768
3769
3770
3771
3772
3773
3774
3775
3776
3777
3778
3779
3780
3781
3782
3783
3784
3785
3786
3787
3788
3789
3790
3791
3792
3793
3794
3795
3796
3797
3798
3799
3800
3801
3802
3803
3804
3805
3806
3807
3808
3809
3810
3811
3812
3813
3814
3815
3816
3817
3818
3819
3820
3821
3822
3823
3824
3825
3826
3827
3828
3829
3830
3831
3832
3833
3834
3835
3836
3837
3838
3839
3840
3841
3842
3843
3844
3845
3846
3847
3848
3849
3850
3851
3852
3853
3854
3855
3856
3857
3858
3859
3860
3861
3862
3863
3864
3865
3866
3867
3868
3869
3870
3871
3872
3873
3874
3875
3876
3877
3878
3879
3880
3881
3882
3883
3884
3885
3886
3887
3888
3889
3890
3891
3892
3893
3894
3895
3896
3897
3898
3899
3900
3901
3902
3903
3904
3905
3906
3907
3908
3909
3910
3911
3912
3913
3914
3915
3916
3917
3918
3919
3920
3921
3922
3923
3924
3925
3926
3927
3928
3929
3930
3931
3932
3933
3934
3935
3936
3937
3938
3939
3940
3941
3942
3943
3944
3945
3946
3947
3948
3949
3950
3951
3952
3953
3954
3955
3956
3957
3958
3959
3960
3961
3962
3963
3964
3965
3966
3967
3968
3969
3970
3971
3972
3973
3974
3975
3976
3977
3978
3979
3980
3981
3982
3983
3984
3985
3986
3987
3988
3989
3990
3991
3992
3993
3994
3995
3996
3997
3998
3999
4000
4001
4002
4003
4004
4005
4006
4007
4008
4009
4010
4011
4012
4013
4014
4015
4016
4017
4018
4019
4020
4021
4022
4023
4024
4025
4026
4027
4028
4029
4030
4031
4032
4033
4034
4035
4036
4037
4038
4039
4040
4041
4042
4043
4044
4045
4046
4047
4048
4049
4050
4051
4052
4053
4054
4055
4056
4057
4058
4059
4060
4061
4062
4063
4064
4065
4066
4067
4068
4069
4070
4071
4072
4073
4074
4075
4076
4077
4078
4079
4080
4081
4082
4083
4084
4085
4086
4087
4088
4089
4090
4091
4092
4093
4094
4095
4096
4097
4098
4099
4100
4101
4102
4103
4104
4105
4106
4107
4108
4109
4110
4111
4112
4113
4114
4115
4116
4117
4118
4119
4120
4121
4122
4123
4124
4125
4126
4127
4128
4129
4130
4131
4132
4133
4134
4135
4136
4137
4138
4139
4140
4141
4142
4143
4144
4145
4146
4147
4148
4149
4150
4151
4152
4153
4154
4155
4156
4157
4158
4159
4160
4161
4162
4163
4164
4165
4166
4167
4168
4169
4170
4171
4172
4173
4174
4175
4176
4177
4178
4179
4180
4181
4182
4183
4184
4185
4186
4187
4188
4189
4190
4191
4192
4193
4194
4195
4196
4197
4198
4199
4200
4201
4202
4203
4204
4205
4206
4207
4208
4209
4210
4211
4212
4213
4214
4215
4216
4217
4218
4219
4220
4221
4222
4223
4224
4225
4226
4227
4228
4229
4230
4231
4232
4233
4234
4235
4236
4237
4238
4239
4240
4241
4242
4243
4244
4245
4246
4247
4248
4249
4250
4251
4252
4253
4254
4255
4256
4257
4258
4259
4260
4261
4262
4263
4264
4265
4266
4267
4268
4269
4270
4271
4272
4273
4274
4275
4276
4277
4278
4279
4280
4281
4282
4283
4284
4285
4286
4287
4288
4289
4290
4291
4292
4293
4294
4295
4296
4297
4298
4299
4300
4301
4302
4303
4304
4305
4306
4307
4308
4309
4310
4311
4312
4313
4314
4315
4316
4317
4318
4319
4320
4321
4322
4323
4324
4325
4326
4327
4328
4329
4330
4331
4332
4333
4334
4335
4336
4337
4338
4339
4340
4341
4342
4343
4344
4345
4346
4347
4348
4349
4350
4351
4352
4353
4354
4355
4356
4357
4358
4359
4360
4361
4362
4363
4364
4365
4366
4367
4368
4369
4370
4371
4372
4373
4374
4375
4376
4377
4378
4379
4380
4381
4382
4383
4384
4385
4386
4387
4388
4389
4390
4391
4392
4393
4394
4395
4396
4397
4398
4399
4400
4401
4402
4403
4404
4405
4406
4407
4408
4409
4410
4411
4412
4413
4414
4415
4416
4417
4418
4419
4420
4421
4422
4423
4424
4425
4426
4427
4428
4429
4430
4431
4432
4433
4434
4435
4436
4437
4438
4439
4440
4441
4442
4443
4444
4445
4446
4447
4448
4449
4450
4451
4452
4453
4454
4455
4456
4457
4458
4459
4460
4461
4462
4463
4464
4465
4466
4467
4468
4469
4470
4471
4472
4473
4474
4475
4476
4477
4478
4479
4480
4481
4482
4483
4484
4485
4486
4487
4488
4489
4490
4491
4492
4493
4494
4495
4496
4497
4498
4499
4500
4501
4502
4503
4504
4505
4506
4507
4508
4509
4510
4511
4512
4513
4514
4515
4516
4517
4518
4519
4520
4521
4522
4523
4524
4525
4526
4527
4528
4529
4530
4531
4532
4533
4534
4535
4536
4537
4538
4539
4540
4541
4542
4543
4544
4545
4546
4547
4548
4549
4550
4551
4552
4553
4554
4555
4556
4557
4558
4559
4560
4561
4562
4563
4564
4565
4566
4567
4568
4569
4570
4571
4572
4573
4574
4575
4576
4577
4578
4579
4580
4581
4582
4583
4584
4585
4586
4587
4588
4589
4590
4591
4592
4593
4594
4595
4596
4597
4598
4599
4600
4601
4602
4603
4604
4605
4606
4607
4608
4609
4610
4611
4612
4613
4614
4615
4616
4617
4618
4619
4620
4621
4622
4623
4624
4625
4626
4627
4628
4629
4630
4631
4632
4633
4634
4635
4636
4637
4638
4639
4640
4641
4642
4643
4644
4645
4646
4647
4648
4649
4650
4651
4652
4653
4654
4655
4656
4657
4658
4659
4660
4661
4662
4663
4664
4665
4666
4667
4668
4669
4670
4671
4672
4673
4674
4675
4676
4677
4678
4679
4680
4681
4682
4683
4684
4685
4686
4687
4688
4689
4690
4691
4692
4693
4694
4695
4696
4697
4698
4699
4700
4701
4702
4703
4704
4705
4706
4707
4708
4709
4710
4711
4712
4713
4714
4715
4716
4717
4718
4719
4720
4721
4722
4723
4724
4725
4726
4727
4728
4729
4730
4731
4732
4733
4734
4735
4736
4737
4738
4739
4740
4741
4742
4743
4744
4745
4746
4747
4748
4749
4750
4751
4752
4753
4754
4755
4756
4757
4758
4759
4760
4761
4762
4763
4764
4765
4766
4767
4768
4769
4770
4771
4772
4773
4774
4775
4776
4777
4778
4779
4780
4781
4782
4783
4784
4785
4786
4787
4788
4789
4790
4791
4792
4793
4794
4795
4796
4797
4798
4799
4800
4801
4802
4803
4804
4805
4806
4807
4808
4809
4810
4811
4812
4813
4814
4815
4816
4817
4818
4819
4820
4821
4822
4823
4824
4825
4826
4827
4828
4829
4830
4831
4832
4833
4834
4835
4836
4837
4838
4839
4840
4841
4842
4843
4844
4845
4846
4847
4848
4849
4850
4851
4852
4853
4854
4855
4856
4857
4858
4859
4860
4861
4862
4863
4864
4865
4866
4867
4868
4869
4870
4871
4872
4873
4874
4875
4876
4877
4878
4879
4880
4881
4882
4883
4884
4885
4886
4887
4888
4889
4890
4891
4892
4893
4894
4895
4896
4897
4898
4899
4900
4901
4902
4903
4904
4905
4906
4907
4908
4909
4910
4911
4912
4913
4914
4915
4916
4917
4918
4919
4920
4921
4922
4923
4924
4925
4926
4927
4928
4929
4930
4931
4932
4933
4934
4935
4936
4937
4938
4939
4940
4941
4942
4943
4944
4945
4946
4947
4948
4949
4950
4951
4952
4953
4954
4955
4956
4957
4958
4959
4960
4961
4962
4963
4964
4965
4966
4967
4968
4969
4970
4971
4972
4973
4974
4975
4976
4977
4978
4979
4980
4981
4982
4983
4984
4985
4986
4987
4988
4989
4990
4991
4992
4993
4994
4995
4996
4997
4998
4999
5000
5001
5002
5003
5004
5005
5006
5007
5008
5009
5010
5011
5012
5013
5014
5015
5016
5017
5018
5019
5020
5021
5022
5023
5024
5025
5026
5027
5028
5029
5030
5031
5032
5033
5034
5035
5036
5037
5038
5039
5040
5041
5042
5043
5044
5045
5046
5047
5048
5049
5050
5051
5052
5053
5054
5055
5056
5057
5058
5059
5060
5061
5062
5063
5064
5065
5066
5067
5068
5069
5070
5071
5072
5073
5074
5075
5076
5077
5078
5079
5080
5081
5082
5083
5084
5085
5086
5087
5088
5089
5090
5091
5092
5093
5094
5095
5096
5097
5098
5099
5100
5101
5102
5103
5104
5105
5106
5107
5108
5109
5110
5111
5112
5113
5114
5115
5116
5117
5118
5119
5120
5121
5122
5123
5124
5125
5126
5127
5128
5129
5130
5131
5132
5133
5134
5135
5136
5137
5138
5139
5140
5141
5142
5143
5144
5145
5146
5147
5148
5149
5150
5151
5152
5153
5154
5155
5156
5157
5158
5159
5160
5161
5162
5163
5164
5165
5166
5167
5168
5169
5170
5171
5172
5173
5174
5175
5176
5177
5178
5179
5180
5181
5182
5183
5184
5185
5186
5187
5188
5189
5190
5191
5192
5193
5194
5195
5196
5197
5198
5199
5200
5201
5202
5203
5204
5205
5206
5207
5208
5209
5210
5211
5212
5213
5214
5215
5216
5217
5218
5219
5220
5221
5222
5223
5224
5225
5226
5227
5228
5229
5230
5231
5232
5233
5234
5235
5236
5237
5238
5239
5240
5241
5242
5243
5244
5245
5246
5247
5248
5249
5250
5251
5252
5253
5254
5255
5256
5257
5258
5259
5260
5261
5262
5263
5264
5265
5266
5267
5268
5269
5270
5271
5272
5273
5274
5275
5276
5277
5278
5279
5280
5281
5282
5283
5284
5285
5286
5287
5288
5289
5290
5291
5292
5293
5294
5295
5296
5297
5298
5299
5300
5301
5302
5303
5304
5305
5306
5307
5308
5309
5310
5311
5312
5313
5314
5315
5316
5317
5318
5319
5320
5321
5322
5323
5324
5325
5326
5327
5328
5329
5330
5331
5332
5333
5334
5335
5336
5337
5338
5339
5340
5341
5342
5343
5344
5345
5346
5347
5348
5349
5350
5351
5352
5353
5354
5355
5356
5357
5358
5359
5360
5361
5362
5363
5364
5365
5366
5367
5368
5369
5370
5371
5372
5373
5374
5375
5376
5377
5378
5379
5380
5381
5382
5383
5384
5385
5386
5387
5388
5389
5390
5391
5392
5393
5394
5395
5396
5397
5398
5399
5400
5401
5402
5403
5404
5405
5406
5407
5408
5409
5410
5411
5412
5413
5414
5415
5416
5417
5418
5419
5420
5421
5422
5423
5424
5425
5426
5427
5428
5429
5430
5431
5432
5433
5434
5435
5436
5437
5438
5439
5440
5441
5442
5443
5444
5445
5446
5447
5448
5449
5450
5451
5452
5453
5454
5455
5456
5457
5458
5459
5460
5461
5462
5463
5464
5465
5466
5467
5468
5469
5470
5471
5472
5473
5474
5475
5476
5477
5478
5479
5480
5481
5482
5483
5484
5485
5486
5487
5488
5489
5490
5491
5492
5493
5494
5495
5496
5497
5498
5499
5500
5501
5502
5503
5504
5505
5506
5507
5508
5509
5510
5511
5512
5513
5514
5515
5516
5517
5518
5519
5520
5521
5522
5523
5524
5525
5526
5527
5528
5529
5530
5531
5532
5533
5534
5535
5536
5537
5538
5539
5540
5541
5542
5543
5544
5545
5546
5547
5548
5549
5550
5551
5552
5553
5554
5555
5556
5557
5558
5559
5560
5561
5562
5563
5564
5565
5566
5567
5568
5569
5570
5571
5572
5573
5574
5575
5576
5577
5578
5579
5580
5581
5582
5583
5584
5585
5586
5587
5588
5589
5590
5591
5592
5593
5594
5595
5596
5597
5598
5599
5600
5601
5602
5603
5604
5605
5606
5607
5608
5609
5610
5611
5612
5613
5614
5615
5616
5617
5618
5619
5620
5621
5622
5623
5624
5625
5626
5627
5628
5629
5630
5631
5632
5633
5634
5635
5636
5637
5638
5639
5640
5641
5642
5643
5644
5645
5646
5647
5648
5649
5650
5651
5652
5653
5654
5655
5656
5657
5658
5659
5660
5661
5662
5663
5664
5665
5666
5667
5668
5669
5670
5671
5672
5673
5674
5675
5676
5677
5678
5679
5680
5681
5682
5683
5684
5685
5686
5687
5688
5689
5690
5691
5692
5693
5694
5695
5696
5697
5698
5699
5700
5701
5702
5703
5704
5705
5706
5707
5708
5709
5710
5711
5712
5713
5714
5715
5716
5717
5718
5719
5720
5721
5722
5723
5724
5725
5726
5727
5728
5729
5730
5731
5732
5733
5734
5735
5736
5737
5738
5739
5740
5741
5742
5743
5744
5745
5746
5747
5748
5749
5750
5751
5752
5753
5754
5755
5756
5757
5758
5759
5760
5761
5762
5763
5764
5765
5766
5767
5768
5769
5770
5771
5772
5773
5774
5775
5776
5777
5778
5779
5780
5781
5782
5783
5784
5785
5786
5787
5788
5789
5790
5791
5792
5793
5794
5795
5796
5797
5798
5799
5800
5801
5802
5803
5804
5805
5806
5807
5808
5809
5810
5811
5812
5813
5814
5815
5816
5817
5818
5819
5820
5821
5822
5823
5824
5825
5826
5827
5828
5829
5830
5831
5832
5833
5834
5835
5836
5837
5838
5839
5840
5841
5842
5843
5844
5845
5846
5847
5848
5849
5850
5851
5852
5853
5854
5855
5856
5857
5858
5859
5860
5861
5862
5863
5864
5865
5866
5867
5868
5869
5870
5871
5872
5873
5874
5875
5876
5877
5878
5879
5880
5881
5882
5883
5884
5885
5886
5887
5888
5889
5890
5891
5892
5893
5894
5895
5896
5897
5898
5899
5900
5901
5902
5903
5904
5905
5906
5907
5908
5909
5910
5911
5912
5913
5914
5915
5916
5917
5918
5919
5920
5921
5922
5923
5924
5925
5926
5927
5928
5929
5930
5931
5932
5933
5934
5935
5936
5937
5938
5939
5940
5941
5942
5943
5944
5945
5946
5947
5948
5949
5950
5951
5952
5953
5954
5955
5956
5957
5958
5959
5960
5961
5962
5963
5964
5965
5966
5967
5968
5969
5970
5971
5972
5973
5974
5975
5976
5977
5978
5979
5980
5981
5982
5983
5984
5985
5986
5987
5988
5989
5990
5991
5992
5993
5994
5995
5996
5997
5998
5999
6000
6001
6002
6003
6004
6005
6006
6007
6008
6009
6010
6011
6012
6013
6014
6015
6016
6017
6018
6019
6020
6021
6022
6023
6024
6025
6026
6027
6028
6029
6030
6031
6032
6033
6034
6035
6036
6037
6038
6039
6040
6041
6042
6043
6044
6045
6046
6047
6048
6049
6050
6051
6052
6053
6054
6055
6056
6057
6058
6059
6060
6061
6062
6063
6064
6065
6066
6067
6068
6069
6070
6071
6072
6073
6074
6075
6076
6077
6078
6079
6080
6081
6082
6083
6084
6085
6086
6087
6088
6089
6090
6091
6092
6093
6094
6095
6096
6097
6098
6099
6100
6101
6102
6103
6104
6105
6106
6107
6108
6109
6110
6111
6112
6113
6114
6115
6116
6117
6118
6119
6120
6121
6122
6123
6124
6125
6126
6127
6128
6129
6130
6131
6132
6133
6134
6135
6136
6137
6138
6139
6140
6141
6142
6143
6144
6145
6146
6147
6148
6149
6150
6151
6152
6153
6154
6155
6156
6157
6158
6159
6160
6161
6162
6163
6164
6165
6166
6167
6168
6169
6170
6171
6172
6173
6174
6175
6176
6177
6178
6179
6180
6181
6182
6183
6184
6185
6186
6187
6188
6189
6190
6191
6192
6193
6194
6195
6196
6197
6198
6199
6200
6201
6202
6203
6204
6205
6206
6207
6208
6209
6210
6211
6212
6213
6214
6215
6216
6217
6218
6219
6220
6221
6222
6223
6224
6225
6226
6227
6228
6229
6230
6231
6232
6233
6234
6235
6236
6237
6238
6239
6240
6241
6242
6243
6244
6245
6246
6247
6248
6249
6250
6251
6252
6253
6254
6255
6256
6257
6258
6259
6260
6261
6262
6263
6264
6265
6266
6267
6268
6269
6270
6271
6272
6273
6274
6275
6276
6277
6278
6279
6280
6281
6282
6283
6284
6285
6286
6287
6288
6289
6290
6291
6292
6293
6294
6295
6296
6297
6298
6299
6300
/*
LodePNG version 20180611

Copyright (c) 2005-2018 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 are in the header file "lodepng.h"
Rename this file to lodepng.cpp to use it for C++, or to lodepng.c to use it for C.
*/

#include "lodepng.h"

#include <limits.h>
#include <stdio.h>
#include <stdlib.h>

#if defined(_MSC_VER) && (_MSC_VER >= 1310) /*Visual Studio: A few warning types are not desired here.*/
#pragma warning( disable : 4244 ) /*implicit conversions: not warned by gcc -Wall -Wextra and requires too much casts*/
#pragma warning( disable : 4996 ) /*VS does not like fopen, but fopen_s is not standard C so unusable here*/
#endif /*_MSC_VER */

const char* LODEPNG_VERSION_STRING = "20180611";

/*
This source file is built up in the following large parts. The code sections
with the "LODEPNG_COMPILE_" #defines divide this up further in an intermixed way.
-Tools for C and common code for PNG and Zlib
-C Code for Zlib (huffman, deflate, ...)
-C Code for PNG (file format chunks, adam7, PNG filters, color conversions, ...)
-The C++ wrapper around all of the above
*/

/*The malloc, realloc and free functions defined here with "lodepng_" in front
of the name, so that you can easily change them to others related to your
platform if needed. Everything else in the code calls these. Pass
-DLODEPNG_NO_COMPILE_ALLOCATORS to the compiler, or comment out
#define LODEPNG_COMPILE_ALLOCATORS in the header, to disable the ones here and
define them in your own project's source files without needing to change
lodepng source code. Don't forget to remove "static" if you copypaste them
from here.*/

#ifdef LODEPNG_COMPILE_ALLOCATORS
static void* lodepng_malloc(size_t size)
{
#ifdef LODEPNG_MAX_ALLOC
  if(size > LODEPNG_MAX_ALLOC) return 0;
#endif
  return malloc(size);
}

static void* lodepng_realloc(void* ptr, size_t new_size)
{
#ifdef LODEPNG_MAX_ALLOC
  if(new_size > LODEPNG_MAX_ALLOC) return 0;
#endif
  return realloc(ptr, new_size);
}

static void lodepng_free(void* ptr)
{
  free(ptr);
}
#else /*LODEPNG_COMPILE_ALLOCATORS*/
void* lodepng_malloc(size_t size);
void* lodepng_realloc(void* ptr, size_t new_size);
void lodepng_free(void* ptr);
#endif /*LODEPNG_COMPILE_ALLOCATORS*/

/* ////////////////////////////////////////////////////////////////////////// */
/* ////////////////////////////////////////////////////////////////////////// */
/* // Tools for C, and common code for PNG and Zlib.                       // */
/* ////////////////////////////////////////////////////////////////////////// */
/* ////////////////////////////////////////////////////////////////////////// */

#define LODEPNG_MAX(a, b) (((a) > (b)) ? (a) : (b))

/*
Often in case of an error a value is assigned to a variable and then it breaks
out of a loop (to go to the cleanup phase of a function). This macro does that.
It makes the error handling code shorter and more readable.

Example: if(!uivector_resizev(&frequencies_ll, 286, 0)) ERROR_BREAK(83);
*/
#define CERROR_BREAK(errorvar, code)\
{\
  errorvar = code;\
  break;\
}

/*version of CERROR_BREAK that assumes the common case where the error variable is named "error"*/
#define ERROR_BREAK(code) CERROR_BREAK(error, code)

/*Set error var to the error code, and return it.*/
#define CERROR_RETURN_ERROR(errorvar, code)\
{\
  errorvar = code;\
  return code;\
}

/*Try the code, if it returns error, also return the error.*/
#define CERROR_TRY_RETURN(call)\
{\
  unsigned error = call;\
  if(error) return error;\
}

/*Set error var to the error code, and return from the void function.*/
#define CERROR_RETURN(errorvar, code)\
{\
  errorvar = code;\
  return;\
}

/*
About uivector, ucvector and string:
-All of them wrap dynamic arrays or text strings in a similar way.
-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 as static functions.
-As with many other structs in this file, the init and cleanup functions serve as ctor and dtor.
*/

#ifdef LODEPNG_COMPILE_ZLIB
/*dynamic vector of unsigned ints*/
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;
  lodepng_free(((uivector*)p)->data);
  ((uivector*)p)->data = NULL;
}

/*returns 1 if success, 0 if failure ==> nothing done*/
static unsigned uivector_reserve(uivector* p, size_t allocsize)
{
  if(allocsize > p->allocsize)
  {
    size_t newsize = (allocsize > p->allocsize * 2) ? allocsize : (allocsize * 3 / 2);
    void* data = lodepng_realloc(p->data, newsize);
    if(data)
    {
      p->allocsize = newsize;
      p->data = (unsigned*)data;
    }
    else return 0; /*error: not enough memory*/
  }
  return 1;
}

/*returns 1 if success, 0 if failure ==> nothing done*/
static unsigned uivector_resize(uivector* p, size_t size)
{
  if(!uivector_reserve(p, size * sizeof(unsigned))) return 0;
  p->size = size;
  return 1; /*success*/
}

/*resize and give all new elements the value*/
static unsigned uivector_resizev(uivector* p, size_t size, unsigned 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;
}

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

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

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

/*returns 1 if success, 0 if failure ==> nothing done*/
static unsigned ucvector_reserve(ucvector* p, size_t allocsize)
{
  if(allocsize > p->allocsize)
  {
    size_t newsize = (allocsize > p->allocsize * 2) ? allocsize : (allocsize * 3 / 2);
    void* data = lodepng_realloc(p->data, newsize);
    if(data)
    {
      p->allocsize = newsize;
      p->data = (unsigned char*)data;
    }
    else return 0; /*error: not enough memory*/
  }
  return 1;
}

/*returns 1 if success, 0 if failure ==> nothing done*/
static unsigned ucvector_resize(ucvector* p, size_t size)
{
  if(!ucvector_reserve(p, size * sizeof(unsigned char))) return 0;
  p->size = size;
  return 1; /*success*/
}

#ifdef LODEPNG_COMPILE_PNG

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

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

#ifdef LODEPNG_COMPILE_ZLIB
/*you can both convert from vector to buffer&size and vica versa. If you use
init_buffer to take over a buffer and size, it is not needed to use cleanup*/
static void ucvector_init_buffer(ucvector* p, unsigned char* buffer, size_t size)
{
  p->data = buffer;
  p->allocsize = p->size = size;
}
#endif /*LODEPNG_COMPILE_ZLIB*/

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


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

#ifdef LODEPNG_COMPILE_PNG
#ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
/*returns 1 if success, 0 if failure ==> nothing done*/
static unsigned string_resize(char** out, size_t size)
{
  char* data = (char*)lodepng_realloc(*out, size + 1);
  if(data)
  {
    data[size] = 0; /*null termination char*/
    *out = data;
  }
  return data != 0;
}

/*init a {char*, size_t} pair for use as string*/
static void string_init(char** out)
{
  *out = NULL;
  string_resize(out, 0);
}

/*free the above pair again*/
static void string_cleanup(char** out)
{
  lodepng_free(*out);
  *out = NULL;
}

static void string_set(char** out, const char* in)
{
  size_t insize = strlen(in), i;
  if(string_resize(out, insize))
  {
    for(i = 0; i != insize; ++i)
    {
      (*out)[i] = in[i];
    }
  }
}
#endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/
#endif /*LODEPNG_COMPILE_PNG*/

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

unsigned lodepng_read32bitInt(const unsigned char* buffer)
{
  return (unsigned)((buffer[0] << 24) | (buffer[1] << 16) | (buffer[2] << 8) | buffer[3]);
}

#if defined(LODEPNG_COMPILE_PNG) || defined(LODEPNG_COMPILE_ENCODER)
/*buffer must have at least 4 allocated bytes available*/
static void lodepng_set32bitInt(unsigned char* buffer, unsigned value)
{
  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);
}
#endif /*defined(LODEPNG_COMPILE_PNG) || defined(LODEPNG_COMPILE_ENCODER)*/

#ifdef LODEPNG_COMPILE_ENCODER
static void lodepng_add32bitInt(ucvector* buffer, unsigned value)
{
  ucvector_resize(buffer, buffer->size + 4); /*todo: give error if resize failed*/
  lodepng_set32bitInt(&buffer->data[buffer->size - 4], value);
}
#endif /*LODEPNG_COMPILE_ENCODER*/

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

#ifdef LODEPNG_COMPILE_DISK

/* returns negative value on error. This should be pure C compatible, so no fstat. */
static long lodepng_filesize(const char* filename)
{
  FILE* file;
  long size;
  file = fopen(filename, "rb");
  if(!file) return -1;

  if(fseek(file, 0, SEEK_END) != 0)
  {
    fclose(file);
    return -1;
  }

  size = ftell(file);
  /* It may give LONG_MAX as directory size, this is invalid for us. */
  if(size == LONG_MAX) size = -1;

  fclose(file);
  return size;
}

/* load file into buffer that already has the correct allocated size. Returns error code.*/
static unsigned lodepng_buffer_file(unsigned char* out, size_t size, const char* filename)
{
  FILE* file;
  size_t readsize;
  file = fopen(filename, "rb");
  if(!file) return 78;

  readsize = fread(out, 1, size, file);
  fclose(file);

  if (readsize != size) return 78;
  return 0;
}

unsigned lodepng_load_file(unsigned char** out, size_t* outsize, const char* filename)
{
  long size = lodepng_filesize(filename);
  if (size < 0) return 78;
  *outsize = (size_t)size;

  *out = (unsigned char*)lodepng_malloc((size_t)size);
  if(!(*out) && size > 0) return 83; /*the above malloc failed*/

  return lodepng_buffer_file(*out, (size_t)size, filename);
}

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

#endif /*LODEPNG_COMPILE_DISK*/

/* ////////////////////////////////////////////////////////////////////////// */
/* ////////////////////////////////////////////////////////////////////////// */
/* // End of common code and tools. Begin of Zlib related code.            // */
/* ////////////////////////////////////////////////////////////////////////// */
/* ////////////////////////////////////////////////////////////////////////// */

#ifdef LODEPNG_COMPILE_ZLIB
#ifdef LODEPNG_COMPILE_ENCODER
/*TODO: this ignores potential out of memory errors*/
#define addBitToStream(/*size_t**/ bitpointer, /*ucvector**/ bitstream, /*unsigned char*/ bit)\
{\
  /*add a new byte at the end*/\
  if(((*bitpointer) & 7) == 0) ucvector_push_back(bitstream, (unsigned char)0);\
  /*earlier bit of huffman code is in a lesser significant bit of an earlier byte*/\
  (bitstream->data[bitstream->size - 1]) |= (bit << ((*bitpointer) & 0x7));\
  ++(*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));
}
#endif /*LODEPNG_COMPILE_ENCODER*/

#ifdef LODEPNG_COMPILE_DECODER

#define READBIT(bitpointer, bitstream) ((bitstream[bitpointer >> 3] >> (bitpointer & 0x7)) & (unsigned char)1)

static unsigned char readBitFromStream(size_t* bitpointer, const unsigned char* bitstream)
{
  unsigned char result = (unsigned char)(READBIT(*bitpointer, bitstream));
  ++(*bitpointer);
  return result;
}

static unsigned readBitsFromStream(size_t* bitpointer, const unsigned char* bitstream, size_t nbits)
{
  unsigned result = 0, i;
  for(i = 0; i != nbits; ++i)
  {
    result += ((unsigned)READBIT(*bitpointer, bitstream)) << i;
    ++(*bitpointer);
  }
  return result;
}
#endif /*LODEPNG_COMPILE_DECODER*/

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

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

/*the base lengths represented by codes 257-285*/
static const unsigned LENGTHBASE[29]
  = {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};

/*the extra bits used by codes 257-285 (added to base length)*/
static const unsigned LENGTHEXTRA[29]
  = {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};

/*the base backwards distances (the bits of distance codes appear after length codes and use their own huffman tree)*/
static const unsigned DISTANCEBASE[30]
  = {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};

/*the extra bits of backwards distances (added to base)*/
static const unsigned DISTANCEEXTRA[30]
  = {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};

/*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*/
static const unsigned CLCL_ORDER[NUM_CODE_LENGTH_CODES]
  = {16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15};

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

/*
Huffman tree struct, containing multiple representations of the tree
*/
typedef struct HuffmanTree
{
  unsigned* tree2d;
  unsigned* tree1d;
  unsigned* 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 to draw the tree in ascii art with C++*/
/*
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)
{
  tree->tree2d = 0;
  tree->tree1d = 0;
  tree->lengths = 0;
}

static void HuffmanTree_cleanup(HuffmanTree* tree)
{
  lodepng_free(tree->tree2d);
  lodepng_free(tree->tree1d);
  lodepng_free(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;

  tree->tree2d = (unsigned*)lodepng_malloc(tree->numcodes * 2 * sizeof(unsigned));
  if(!tree->tree2d) return 83; /*alloc fail*/

  /*
  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 huffman 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[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[n]; ++i) /*the bits for this code*/
    {
      unsigned char bit = (unsigned char)((tree->tree1d[n] >> (tree->lengths[n] - i - 1)) & 1);
      /*oversubscribed, see comment in lodepng_error_text*/
      if(treepos > 2147483647 || treepos + 2 > tree->numcodes) return 55;
      if(tree->tree2d[2 * treepos + bit] == 32767) /*not yet filled in*/
      {
        if(i + 1 == tree->lengths[n]) /*last bit*/
        {
          tree->tree2d[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;
          /*addresses encoded with numcodes added to it*/
          tree->tree2d[2 * treepos + bit] = nodefilled + tree->numcodes;
          treepos = nodefilled;
        }
      }
      else treepos = tree->tree2d[2 * treepos + bit] - tree->numcodes;
    }
  }

  for(n = 0; n < tree->numcodes * 2; ++n)
  {
    if(tree->tree2d[n] == 32767) tree->tree2d[n] = 0; /*remove possible remaining 32767's*/
  }

  return 0;
}

/*
Second step for the ...makeFromLengths and ...makeFromFrequencies functions.
numcodes, lengths and maxbitlen must already be filled in correctly. return
value is error.
*/
static unsigned HuffmanTree_makeFromLengths2(HuffmanTree* tree)
{
  uivector blcount;
  uivector nextcode;
  unsigned error = 0;
  unsigned bits, n;

  uivector_init(&blcount);
  uivector_init(&nextcode);

  tree->tree1d = (unsigned*)lodepng_malloc(tree->numcodes * sizeof(unsigned));
  if(!tree->tree1d) error = 83; /*alloc fail*/

  if(!uivector_resizev(&blcount, tree->maxbitlen + 1, 0)
  || !uivector_resizev(&nextcode, tree->maxbitlen + 1, 0))
    error = 83; /*alloc fail*/

  if(!error)
  {
    /*step 1: count number of instances of each code length*/
    for(bits = 0; bits != tree->numcodes; ++bits) ++blcount.data[tree->lengths[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[n] != 0) tree->tree1d[n] = nextcode.data[tree->lengths[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;
  tree->lengths = (unsigned*)lodepng_malloc(numcodes * sizeof(unsigned));
  if(!tree->lengths) return 83; /*alloc fail*/
  for(i = 0; i != numcodes; ++i) tree->lengths[i] = bitlen[i];
  tree->numcodes = (unsigned)numcodes; /*number of symbols*/
  tree->maxbitlen = maxbitlen;
  return HuffmanTree_makeFromLengths2(tree);
}

#ifdef LODEPNG_COMPILE_ENCODER

/*BPM: Boundary Package Merge, see "A Fast and Space-Economical Algorithm for Length-Limited Coding",
Jyrki Katajainen, Alistair Moffat, Andrew Turpin, 1995.*/

/*chain node for boundary package merge*/
typedef struct BPMNode
{
  int weight; /*the sum of all weights in this chain*/
  unsigned index; /*index of this leaf node (called "count" in the paper)*/
  struct BPMNode* tail; /*the next nodes in this chain (null if last)*/
  int in_use;
} BPMNode;

/*lists of chains*/
typedef struct BPMLists
{
  /*memory pool*/
  unsigned memsize;
  BPMNode* memory;
  unsigned numfree;
  unsigned nextfree;
  BPMNode** freelist;
  /*two heads of lookahead chains per list*/
  unsigned listsize;
  BPMNode** chains0;
  BPMNode** chains1;
} BPMLists;

/*creates a new chain node with the given parameters, from the memory in the lists */
static BPMNode* bpmnode_create(BPMLists* lists, int weight, unsigned index, BPMNode* tail)
{
  unsigned i;
  BPMNode* result;

  /*memory full, so garbage collect*/
  if(lists->nextfree >= lists->numfree)
  {
    /*mark only those that are in use*/
    for(i = 0; i != lists->memsize; ++i) lists->memory[i].in_use = 0;
    for(i = 0; i != lists->listsize; ++i)
    {
      BPMNode* node;
      for(node = lists->chains0[i]; node != 0; node = node->tail) node->in_use = 1;
      for(node = lists->chains1[i]; node != 0; node = node->tail) node->in_use = 1;
    }
    /*collect those that are free*/
    lists->numfree = 0;
    for(i = 0; i != lists->memsize; ++i)
    {
      if(!lists->memory[i].in_use) lists->freelist[lists->numfree++] = &lists->memory[i];
    }
    lists->nextfree = 0;
  }

  result = lists->freelist[lists->nextfree++];
  result->weight = weight;
  result->index = index;
  result->tail = tail;
  return result;
}

/*sort the leaves with stable mergesort*/
static void bpmnode_sort(BPMNode* leaves, size_t num)
{
  BPMNode* mem = (BPMNode*)lodepng_malloc(sizeof(*leaves) * num);
  size_t width, counter = 0;
  for(width = 1; width < num; width *= 2)
  {
    BPMNode* a = (counter & 1) ? mem : leaves;
    BPMNode* b = (counter & 1) ? leaves : mem;
    size_t p;
    for(p = 0; p < num; p += 2 * width)
    {
      size_t q = (p + width > num) ? num : (p + width);
      size_t r = (p + 2 * width > num) ? num : (p + 2 * width);
      size_t i = p, j = q, k;
      for(k = p; k < r; k++)
      {
        if(i < q && (j >= r || a[i].weight <= a[j].weight)) b[k] = a[i++];
        else b[k] = a[j++];
      }
    }
    counter++;
  }
  if(counter & 1) memcpy(leaves, mem, sizeof(*leaves) * num);
  lodepng_free(mem);
}

/*Boundary Package Merge step, numpresent is the amount of leaves, and c is the current chain.*/
static void boundaryPM(BPMLists* lists, BPMNode* leaves, size_t numpresent, int c, int num)
{
  unsigned lastindex = lists->chains1[c]->index;

  if(c == 0)
  {
    if(lastindex >= numpresent) return;
    lists->chains0[c] = lists->chains1[c];
    lists->chains1[c] = bpmnode_create(lists, leaves[lastindex].weight, lastindex + 1, 0);
  }
  else
  {
    /*sum of the weights of the head nodes of the previous lookahead chains.*/
    int sum = lists->chains0[c - 1]->weight + lists->chains1[c - 1]->weight;
    lists->chains0[c] = lists->chains1[c];
    if(lastindex < numpresent && sum > leaves[lastindex].weight)
    {
      lists->chains1[c] = bpmnode_create(lists, leaves[lastindex].weight, lastindex + 1, lists->chains1[c]->tail);
      return;
    }
    lists->chains1[c] = bpmnode_create(lists, sum, lastindex, lists->chains1[c - 1]);
    /*in the end we are only interested in the chain of the last list, so no
    need to recurse if we're at the last one (this gives measurable speedup)*/
    if(num + 1 < (int)(2 * numpresent - 2))
    {
      boundaryPM(lists, leaves, numpresent, c - 1, num);
      boundaryPM(lists, leaves, numpresent, c - 1, num);
    }
  }
}

unsigned lodepng_huffman_code_lengths(unsigned* lengths, const unsigned* frequencies,
                                      size_t numcodes, unsigned maxbitlen)
{
  unsigned error = 0;
  unsigned i;
  size_t numpresent = 0; /*number of symbols with non-zero frequency*/
  BPMNode* leaves; /*the symbols, only those with > 0 frequency*/

  if(numcodes == 0) return 80; /*error: a tree of 0 symbols is not supposed to be made*/
  if((1u << maxbitlen) < (unsigned)numcodes) return 80; /*error: represent all symbols*/

  leaves = (BPMNode*)lodepng_malloc(numcodes * sizeof(*leaves));
  if(!leaves) return 83; /*alloc fail*/

  for(i = 0; i != numcodes; ++i)
  {
    if(frequencies[i] > 0)
    {
      leaves[numpresent].weight = (int)frequencies[i];
      leaves[numpresent].index = i;
      ++numpresent;
    }
  }

  for(i = 0; i != numcodes; ++i) lengths[i] = 0;

  /*ensure at least two present symbols. There should be at least one symbol
  according to RFC 1951 section 3.2.7. Some decoders incorrectly require two. To
  make these work as well ensure there are at least two symbols. The
  Package-Merge code below also doesn't work correctly if there's only one
  symbol, it'd give it the theoritical 0 bits but in practice zlib wants 1 bit*/
  if(numpresent == 0)
  {
    lengths[0] = lengths[1] = 1; /*note that for RFC 1951 section 3.2.7, only lengths[0] = 1 is needed*/
  }
  else if(numpresent == 1)
  {
    lengths[leaves[0].index] = 1;
    lengths[leaves[0].index == 0 ? 1 : 0] = 1;
  }
  else
  {
    BPMLists lists;
    BPMNode* node;

    bpmnode_sort(leaves, numpresent);

    lists.listsize = maxbitlen;
    lists.memsize = 2 * maxbitlen * (maxbitlen + 1);
    lists.nextfree = 0;
    lists.numfree = lists.memsize;
    lists.memory = (BPMNode*)lodepng_malloc(lists.memsize * sizeof(*lists.memory));
    lists.freelist = (BPMNode**)lodepng_malloc(lists.memsize * sizeof(BPMNode*));
    lists.chains0 = (BPMNode**)lodepng_malloc(lists.listsize * sizeof(BPMNode*));
    lists.chains1 = (BPMNode**)lodepng_malloc(lists.listsize * sizeof(BPMNode*));
    if(!lists.memory || !lists.freelist || !lists.chains0 || !lists.chains1) error = 83; /*alloc fail*/

    if(!error)
    {
      for(i = 0; i != lists.memsize; ++i) lists.freelist[i] = &lists.memory[i];

      bpmnode_create(&lists, leaves[0].weight, 1, 0);
      bpmnode_create(&lists, leaves[1].weight, 2, 0);

      for(i = 0; i != lists.listsize; ++i)
      {
        lists.chains0[i] = &lists.memory[0];
        lists.chains1[i] = &lists.memory[1];
      }

      /*each boundaryPM call adds one chain to the last list, and we need 2 * numpresent - 2 chains.*/
      for(i = 2; i != 2 * numpresent - 2; ++i) boundaryPM(&lists, leaves, numpresent, (int)maxbitlen - 1, (int)i);

      for(node = lists.chains1[maxbitlen - 1]; node; node = node->tail)
      {
        for(i = 0; i != node->index; ++i) ++lengths[leaves[i].index];
      }
    }

    lodepng_free(lists.memory);
    lodepng_free(lists.freelist);
    lodepng_free(lists.chains0);
    lodepng_free(lists.chains1);
  }

  lodepng_free(leaves);
  return error;
}

/*Create the Huffman tree given the symbol frequencies*/
static unsigned HuffmanTree_makeFromFrequencies(HuffmanTree* tree, const unsigned* frequencies,
                                                size_t mincodes, size_t numcodes, unsigned maxbitlen)
{
  unsigned error = 0;
  while(!frequencies[numcodes - 1] && numcodes > mincodes) --numcodes; /*trim zeroes*/
  tree->maxbitlen = maxbitlen;
  tree->numcodes = (unsigned)numcodes; /*number of symbols*/
  tree->lengths = (unsigned*)lodepng_realloc(tree->lengths, numcodes * sizeof(unsigned));
  if(!tree->lengths) return 83; /*alloc fail*/
  /*initialize all lengths to 0*/
  memset(tree->lengths, 0, numcodes * sizeof(unsigned));

  error = lodepng_huffman_code_lengths(tree->lengths, frequencies, numcodes, maxbitlen);
  if(!error) error = HuffmanTree_makeFromLengths2(tree);
  return error;
}

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

static unsigned HuffmanTree_getLength(const HuffmanTree* tree, unsigned index)
{
  return tree->lengths[index];
}
#endif /*LODEPNG_COMPILE_ENCODER*/

/*get the literal and length code tree of a deflated block with fixed tree, as per the deflate specification*/
static unsigned generateFixedLitLenTree(HuffmanTree* tree)
{
  unsigned i, error = 0;
  unsigned* bitlen = (unsigned*)lodepng_malloc(NUM_DEFLATE_CODE_SYMBOLS * sizeof(unsigned));
  if(!bitlen) return 83; /*alloc fail*/

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

  error = HuffmanTree_makeFromLengths(tree, bitlen, NUM_DEFLATE_CODE_SYMBOLS, 15);

  lodepng_free(bitlen);
  return error;
}

/*get the distance code tree of a deflated block with fixed tree, as specified in the deflate specification*/
static unsigned generateFixedDistanceTree(HuffmanTree* tree)
{
  unsigned i, error = 0;
  unsigned* bitlen = (unsigned*)lodepng_malloc(NUM_DISTANCE_SYMBOLS * sizeof(unsigned));
  if(!bitlen) return 83; /*alloc fail*/

  /*there are 32 distance codes, but 30-31 are unused*/
  for(i = 0; i != NUM_DISTANCE_SYMBOLS; ++i) bitlen[i] = 5;
  error = HuffmanTree_makeFromLengths(tree, bitlen, NUM_DISTANCE_SYMBOLS, 15);

  lodepng_free(bitlen);
  return error;
}

#ifdef LODEPNG_COMPILE_DECODER

/*
returns the code, or (unsigned)(-1) if error happened
inbitlength is the length of the complete buffer, in bits (so its byte length times 8)
*/
static unsigned huffmanDecodeSymbol(const unsigned char* in, size_t* bp,
                                    const HuffmanTree* codetree, size_t inbitlength)
{
  unsigned treepos = 0, ct;
  for(;;)
  {
    if(*bp >= inbitlength) return (unsigned)(-1); /*error: end of input memory reached without endcode*/
    /*
    decode the symbol from the tree. The "readBitFromStream" code is inlined in
    the expression below because this is the biggest bottleneck while decoding
    */
    ct = codetree->tree2d[(treepos << 1) + READBIT(*bp, in)];
    ++(*bp);
    if(ct < codetree->numcodes) return ct; /*the symbol is decoded, return it*/
    else treepos = ct - codetree->numcodes; /*symbol not yet decoded, instead move tree position*/

    if(treepos >= codetree->numcodes) return (unsigned)(-1); /*error: it appeared outside the codetree*/
  }
}
#endif /*LODEPNG_COMPILE_DECODER*/

#ifdef LODEPNG_COMPILE_DECODER

/* ////////////////////////////////////////////////////////////////////////// */
/* / Inflator (Decompressor)                                                / */
/* ////////////////////////////////////////////////////////////////////////// */

/*get the tree of a deflated block with fixed tree, as specified in the deflate specification*/
static void getTreeInflateFixed(HuffmanTree* tree_ll, HuffmanTree* tree_d)
{
  /*TODO: check for out of memory errors*/
  generateFixedLitLenTree(tree_ll);
  generateFixedDistanceTree(tree_d);
}

/*get the tree of a deflated block with dynamic tree, the tree itself is also Huffman compressed with a known tree*/
static unsigned getTreeInflateDynamic(HuffmanTree* tree_ll, HuffmanTree* tree_d,
                                      const unsigned char* in, size_t* bp, size_t inlength)
{
  /*make sure that length values that aren't filled in will be 0, or a wrong tree will be generated*/
  unsigned error = 0;
  unsigned n, HLIT, HDIST, HCLEN, i;
  size_t inbitlength = inlength * 8;

  /*see comments in deflateDynamic for explanation of the context and these variables, it is analogous*/
  unsigned* bitlen_ll = 0; /*lit,len code lengths*/
  unsigned* bitlen_d = 0; /*dist code lengths*/
  /*code length code lengths ("clcl"), the bit lengths of the huffman tree used to compress bitlen_ll and bitlen_d*/
  unsigned* bitlen_cl = 0;
  HuffmanTree tree_cl; /*the code tree for code length codes (the huffman tree for compressed huffman trees)*/

  if((*bp) + 14 > (inlength << 3)) return 49; /*error: the bit pointer is or will go past the memory*/

  /*number of literal/length codes + 257. Unlike the spec, the value 257 is added to it here already*/
  HLIT =  readBitsFromStream(bp, in, 5) + 257;
  /*number of distance codes. Unlike the spec, the value 1 is added to it here already*/
  HDIST = readBitsFromStream(bp, in, 5) + 1;
  /*number of code length codes. Unlike the spec, the value 4 is added to it here already*/
  HCLEN = readBitsFromStream(bp, in, 4) + 4;

  if((*bp) + HCLEN * 3 > (inlength << 3)) return 50; /*error: the bit pointer is or will go past the memory*/

  HuffmanTree_init(&tree_cl);

  while(!error)
  {
    /*read the code length codes out of 3 * (amount of code length codes) bits*/

    bitlen_cl = (unsigned*)lodepng_malloc(NUM_CODE_LENGTH_CODES * sizeof(unsigned));
    if(!bitlen_cl) ERROR_BREAK(83 /*alloc fail*/);

    for(i = 0; i != NUM_CODE_LENGTH_CODES; ++i)
    {
      if(i < HCLEN) bitlen_cl[CLCL_ORDER[i]] = readBitsFromStream(bp, in, 3);
      else bitlen_cl[CLCL_ORDER[i]] = 0; /*if not, it must stay 0*/
    }

    error = HuffmanTree_makeFromLengths(&tree_cl, bitlen_cl, NUM_CODE_LENGTH_CODES, 7);
    if(error) break;

    /*now we can use this tree to read the lengths for the tree that this function will return*/
    bitlen_ll = (unsigned*)lodepng_malloc(NUM_DEFLATE_CODE_SYMBOLS * sizeof(unsigned));
    bitlen_d = (unsigned*)lodepng_malloc(NUM_DISTANCE_SYMBOLS * sizeof(unsigned));
    if(!bitlen_ll || !bitlen_d) ERROR_BREAK(83 /*alloc fail*/);
    for(i = 0; i != NUM_DEFLATE_CODE_SYMBOLS; ++i) bitlen_ll[i] = 0;
    for(i = 0; i != NUM_DISTANCE_SYMBOLS; ++i) bitlen_d[i] = 0;

    /*i is the current symbol we're reading in the part that contains the code lengths of lit/len and dist codes*/
    i = 0;
    while(i < HLIT + HDIST)
    {
      unsigned code = huffmanDecodeSymbol(in, bp, &tree_cl, inbitlength);
      if(code <= 15) /*a length code*/
      {
        if(i < HLIT) bitlen_ll[i] = code;
        else bitlen_d[i - HLIT] = code;
        ++i;
      }
      else if(code == 16) /*repeat previous*/
      {
        unsigned replength = 3; /*read in the 2 bits that indicate repeat length (3-6)*/
        unsigned value; /*set value to the previous code*/

        if(i == 0) ERROR_BREAK(54); /*can't repeat previous if i is 0*/

        if((*bp + 2) > inbitlength) ERROR_BREAK(50); /*error, bit pointer jumps past memory*/
        replength += readBitsFromStream(bp, in, 2);

        if(i < HLIT + 1) value = bitlen_ll[i - 1];
        else value = bitlen_d[i - HLIT - 1];
        /*repeat this value in the next lengths*/
        for(n = 0; n < replength; ++n)
        {
          if(i >= HLIT + HDIST) ERROR_BREAK(13); /*error: i is larger than the amount of codes*/
          if(i < HLIT) bitlen_ll[i] = value;
          else bitlen_d[i - HLIT] = value;
          ++i;
        }
      }
      else if(code == 17) /*repeat "0" 3-10 times*/
      {
        unsigned replength = 3; /*read in the bits that indicate repeat length*/
        if((*bp + 3) > inbitlength) ERROR_BREAK(50); /*error, bit pointer jumps past memory*/
        replength += readBitsFromStream(bp, in, 3);

        /*repeat this value in the next lengths*/
        for(n = 0; n < replength; ++n)
        {
          if(i >= HLIT + HDIST) ERROR_BREAK(14); /*error: i is larger than the amount of codes*/

          if(i < HLIT) bitlen_ll[i] = 0;
          else bitlen_d[i - HLIT] = 0;
          ++i;
        }
      }
      else if(code == 18) /*repeat "0" 11-138 times*/
      {
        unsigned replength = 11; /*read in the bits that indicate repeat length*/
        if((*bp + 7) > inbitlength) ERROR_BREAK(50); /*error, bit pointer jumps past memory*/
        replength += readBitsFromStream(bp, in, 7);

        /*repeat this value in the next lengths*/
        for(n = 0; n < replength; ++n)
        {
          if(i >= HLIT + HDIST) ERROR_BREAK(15); /*error: i is larger than the amount of codes*/

          if(i < HLIT) bitlen_ll[i] = 0;
          else bitlen_d[i - HLIT] = 0;
          ++i;
        }
      }
      else /*if(code == (unsigned)(-1))*/ /*huffmanDecodeSymbol returns (unsigned)(-1) in case of error*/
      {
        if(code == (unsigned)(-1))
        {
          /*return error code 10 or 11 depending on the situation that happened in huffmanDecodeSymbol
          (10=no endcode, 11=wrong jump outside of tree)*/
          error = (*bp) > inbitlength ? 10 : 11;
        }
        else error = 16; /*unexisting code, this can never happen*/
        break;
      }
    }
    if(error) break;

    if(bitlen_ll[256] == 0) ERROR_BREAK(64); /*the length of the end code 256 must be larger than 0*/

    /*now we've finally got HLIT and HDIST, so generate the code trees, and the function is done*/
    error = HuffmanTree_makeFromLengths(tree_ll, bitlen_ll, NUM_DEFLATE_CODE_SYMBOLS, 15);
    if(error) break;
    error = HuffmanTree_makeFromLengths(tree_d, bitlen_d, NUM_DISTANCE_SYMBOLS, 15);

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

  lodepng_free(bitlen_cl);
  lodepng_free(bitlen_ll);
  lodepng_free(bitlen_d);
  HuffmanTree_cleanup(&tree_cl);

  return error;
}

/*inflate a block with dynamic of fixed Huffman tree*/
static unsigned inflateHuffmanBlock(ucvector* out, const unsigned char* in, size_t* bp,
                                    size_t* pos, size_t inlength, unsigned btype)
{
  unsigned error = 0;
  HuffmanTree tree_ll; /*the huffman tree for literal and length codes*/
  HuffmanTree tree_d; /*the huffman tree for distance codes*/
  size_t inbitlength = inlength * 8;

  HuffmanTree_init(&tree_ll);
  HuffmanTree_init(&tree_d);

  if(btype == 1) getTreeInflateFixed(&tree_ll, &tree_d);
  else if(btype == 2) error = getTreeInflateDynamic(&tree_ll, &tree_d, in, bp, inlength);

  while(!error) /*decode all symbols until end reached, breaks at end code*/
  {
    /*code_ll is literal, length or end code*/
    unsigned code_ll = huffmanDecodeSymbol(in, bp, &tree_ll, inbitlength);
    if(code_ll <= 255) /*literal symbol*/
    {
      /*ucvector_push_back would do the same, but for some reason the two lines below run 10% faster*/
      if(!ucvector_resize(out, (*pos) + 1)) ERROR_BREAK(83 /*alloc fail*/);
      out->data[*pos] = (unsigned char)code_ll;
      ++(*pos);
    }
    else if(code_ll >= FIRST_LENGTH_CODE_INDEX && code_ll <= LAST_LENGTH_CODE_INDEX) /*length code*/
    {
      unsigned code_d, distance;
      unsigned numextrabits_l, numextrabits_d; /*extra bits for length and distance*/
      size_t start, forward, backward, length;

      /*part 1: get length base*/
      length = LENGTHBASE[code_ll - FIRST_LENGTH_CODE_INDEX];

      /*part 2: get extra bits and add the value of that to length*/
      numextrabits_l = LENGTHEXTRA[code_ll - FIRST_LENGTH_CODE_INDEX];
      if((*bp + numextrabits_l) > inbitlength) ERROR_BREAK(51); /*error, bit pointer will jump past memory*/
      length += readBitsFromStream(bp, in, numextrabits_l);

      /*part 3: get distance code*/
      code_d = huffmanDecodeSymbol(in, bp, &tree_d, inbitlength);
      if(code_d > 29)
      {
        if(code_d == (unsigned)(-1)) /*huffmanDecodeSymbol returns (unsigned)(-1) in case of error*/
        {
          /*return error code 10 or 11 depending on the situation that happened in huffmanDecodeSymbol
          (10=no endcode, 11=wrong jump outside of tree)*/
          error = (*bp) > inlength * 8 ? 10 : 11;
        }
        else error = 18; /*error: invalid distance code (30-31 are never used)*/
        break;
      }
      distance = DISTANCEBASE[code_d];

      /*part 4: get extra bits from distance*/
      numextrabits_d = DISTANCEEXTRA[code_d];
      if((*bp + numextrabits_d) > inbitlength) ERROR_BREAK(51); /*error, bit pointer will jump past memory*/
      distance += readBitsFromStream(bp, in, numextrabits_d);

      /*part 5: fill in all the out[n] values based on the length and dist*/
      start = (*pos);
      if(distance > start) ERROR_BREAK(52); /*too long backward distance*/
      backward = start - distance;

      if(!ucvector_resize(out, (*pos) + length)) ERROR_BREAK(83 /*alloc fail*/);
      if (distance < length) {
        for(forward = 0; forward < length; ++forward)
        {
          out->data[(*pos)++] = out->data[backward++];
        }
      } else {
        memcpy(out->data + *pos, out->data + backward, length);
        *pos += length;
      }
    }
    else if(code_ll == 256)
    {
      break; /*end code, break the loop*/
    }
    else /*if(code == (unsigned)(-1))*/ /*huffmanDecodeSymbol returns (unsigned)(-1) in case of error*/
    {
      /*return error code 10 or 11 depending on the situation that happened in huffmanDecodeSymbol
      (10=no endcode, 11=wrong jump outside of tree)*/
      error = ((*bp) > inlength * 8) ? 10 : 11;
      break;
    }
  }

  HuffmanTree_cleanup(&tree_ll);
  HuffmanTree_cleanup(&tree_d);

  return error;
}

static unsigned inflateNoCompression(ucvector* out, const unsigned char* in, size_t* bp, size_t* pos, size_t inlength)
{
  size_t p;
  unsigned LEN, NLEN, n, error = 0;

  /*go to first boundary of byte*/
  while(((*bp) & 0x7) != 0) ++(*bp);
  p = (*bp) / 8; /*byte position*/

  /*read LEN (2 bytes) and NLEN (2 bytes)*/
  if(p + 4 >= inlength) return 52; /*error, bit pointer will jump past memory*/
  LEN = in[p] + 256u * in[p + 1]; p += 2;
  NLEN = in[p] + 256u * in[p + 1]; p += 2;

  /*check if 16-bit NLEN is really the one's complement of LEN*/
  if(LEN + NLEN != 65535) return 21; /*error: NLEN is not one's complement of LEN*/

  if(!ucvector_resize(out, (*pos) + LEN)) return 83; /*alloc fail*/

  /*read the literal data: LEN bytes are now stored in the out buffer*/
  if(p + LEN > inlength) return 23; /*error: reading outside of in buffer*/
  for(n = 0; n < LEN; ++n) out->data[(*pos)++] = in[p++];

  (*bp) = p * 8;

  return error;
}

static unsigned lodepng_inflatev(ucvector* out,
                                 const unsigned char* in, size_t insize,
                                 const LodePNGDecompressSettings* settings)
{
  /*bit pointer in the "in" data, current byte is bp >> 3, current bit is bp & 0x7 (from lsb to msb of the byte)*/
  size_t bp = 0;
  unsigned BFINAL = 0;
  size_t pos = 0; /*byte position in the out buffer*/
  unsigned error = 0;

  (void)settings;

  while(!BFINAL)
  {
    unsigned BTYPE;
    if(bp + 2 >= insize * 8) return 52; /*error, bit pointer will jump past memory*/
    BFINAL = readBitFromStream(&bp, in);
    BTYPE = 1u * readBitFromStream(&bp, in);
    BTYPE += 2u * readBitFromStream(&bp, in);

    if(BTYPE == 3) return 20; /*error: invalid BTYPE*/
    else if(BTYPE == 0) error = inflateNoCompression(out, in, &bp, &pos, insize); /*no compression*/
    else error = inflateHuffmanBlock(out, in, &bp, &pos, insize, BTYPE); /*compression, BTYPE 01 or 10*/

    if(error) return error;
  }

  return error;
}

unsigned lodepng_inflate(unsigned char** out, size_t* outsize,
                         const unsigned char* in, size_t insize,
                         const LodePNGDecompressSettings* settings)
{
  unsigned error;
  ucvector v;
  ucvector_init_buffer(&v, *out, *outsize);
  error = lodepng_inflatev(&v, in, insize, settings);
  *out = v.data;
  *outsize = v.size;
  return error;
}

static unsigned inflate(unsigned char** out, size_t* outsize,
                        const unsigned char* in, size_t insize,
                        const LodePNGDecompressSettings* settings)
{
  if(settings->custom_inflate)
  {
    return settings->custom_inflate(out, outsize, in, insize, settings);
  }
  else
  {
    return lodepng_inflate(out, outsize, in, insize, settings);
  }
}

#endif /*LODEPNG_COMPILE_DECODER*/

#ifdef LODEPNG_COMPILE_ENCODER

/* ////////////////////////////////////////////////////////////////////////// */
/* / Deflator (Compressor)                                                  / */
/* ////////////////////////////////////////////////////////////////////////// */

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)
{
  /*binary search (only small gain over linear). TODO: use CPU log2 instruction for getting symbols instead*/
  size_t left = 1;
  size_t right = array_size - 1;

  while(left <= right) {
    size_t mid = (left + right) >> 1;
    if (array[mid] >= value) right = mid - 1;
    else left = mid + 1;
  }
  if(left >= array_size || array[left] > value) left--;
  return left;
}

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);
}

/*3 bytes of data get encoded into two bytes. The hash cannot use more than 3
bytes as input because 3 is the minimum match length for deflate*/
static const unsigned HASH_NUM_VALUES = 65536;
static const unsigned HASH_BIT_MASK = 65535; /*HASH_NUM_VALUES - 1, but C90 does not like that as initializer*/

typedef struct Hash
{
  int* head; /*hash value to head circular pos - can be outdated if went around window*/
  /*circular pos to prev circular pos*/
  unsigned short* chain;
  int* val; /*circular pos to hash value*/

  /*TODO: do this not only for zeros but for any repeated byte. However for PNG
  it's always going to be the zeros that dominate, so not important for PNG*/
  int* headz; /*similar to head, but for chainz*/
  unsigned short* chainz; /*those with same amount of zeros*/
  unsigned short* zeros; /*length of zeros streak, used as a second hash chain*/
} Hash;

static unsigned hash_init(Hash* hash, unsigned windowsize)
{
  unsigned i;
  hash->head = (int*)lodepng_malloc(sizeof(int) * HASH_NUM_VALUES);
  hash->val = (int*)lodepng_malloc(sizeof(int) * windowsize);
  hash->chain = (unsigned short*)lodepng_malloc(sizeof(unsigned short) * windowsize);

  hash->zeros = (unsigned short*)lodepng_malloc(sizeof(unsigned short) * windowsize);
  hash->headz = (int*)lodepng_malloc(sizeof(int) * (MAX_SUPPORTED_DEFLATE_LENGTH + 1));
  hash->chainz = (unsigned short*)lodepng_malloc(sizeof(unsigned short) * windowsize);

  if(!hash->head || !hash->chain || !hash->val  || !hash->headz|| !hash->chainz || !hash->zeros)
  {
    return 83; /*alloc fail*/
  }

  /*initialize hash table*/
  for(i = 0; i != HASH_NUM_VALUES; ++i) hash->head[i] = -1;
  for(i = 0; i != windowsize; ++i) hash->val[i] = -1;
  for(i = 0; i != windowsize; ++i) hash->chain[i] = i; /*same value as index indicates uninitialized*/

  for(i = 0; i <= MAX_SUPPORTED_DEFLATE_LENGTH; ++i) hash->headz[i] = -1;
  for(i = 0; i != windowsize; ++i) hash->chainz[i] = i; /*same value as index indicates uninitialized*/

  return 0;
}

static void hash_cleanup(Hash* hash)
{
  lodepng_free(hash->head);
  lodepng_free(hash->val);
  lodepng_free(hash->chain);

  lodepng_free(hash->zeros);
  lodepng_free(hash->headz);
  lodepng_free(hash->chainz);
}



static unsigned getHash(const unsigned char* data, size_t size, size_t pos)
{
  unsigned result = 0;
  if(pos + 2 < size)
  {
    /*A simple shift and xor hash is used. Since the data of PNGs is dominated
    by zeroes due to the filters, a better hash does not have a significant
    effect on speed in traversing the chain, and causes more time spend on
    calculating the hash.*/
    result ^= (unsigned)(data[pos + 0] << 0u);
    result ^= (unsigned)(data[pos + 1] << 4u);
    result ^= (unsigned)(data[pos + 2] << 8u);
  } else {
    size_t amount, i;
    if(pos >= size) return 0;
    amount = size - pos;
    for(i = 0; i != amount; ++i) result ^= (unsigned)(data[pos + i] << (i * 8u));
  }
  return result & HASH_BIT_MASK;
}

static unsigned countZeros(const unsigned char* data, size_t size, size_t pos)
{
  const unsigned char* start = data + pos;
  const unsigned char* end = start + MAX_SUPPORTED_DEFLATE_LENGTH;
  if(end > data + size) end = data + size;
  data = start;
  while(data != end && *data == 0) ++data;
  /*subtracting two addresses returned as 32-bit number (max value is MAX_SUPPORTED_DEFLATE_LENGTH)*/
  return (unsigned)(data - start);
}

/*wpos = pos & (windowsize - 1)*/
static void updateHashChain(Hash* hash, size_t wpos, unsigned hashval, unsigned short numzeros)
{
  hash->val[wpos] = (int)hashval;
  if(hash->head[hashval] != -1) hash->chain[wpos] = hash->head[hashval];
  hash->head[hashval] = (int)wpos;

  hash->zeros[wpos] = numzeros;
  if(hash->headz[numzeros] != -1) hash->chainz[wpos] = hash->headz[numzeros];
  hash->headz[numzeros] = (int)wpos;
}

/*
LZ77-encode the data. Return value is error code. The input are raw bytes, the output
is in the form of unsigned integers with codes representing for example literal bytes, or
length/distance pairs.
It uses a hash table technique to let it encode faster. When doing LZ77 encoding, a
sliding window (of windowsize) is used, and all past bytes in that window can be used as
the "dictionary". A brute force search through all possible distances would be slow, and
this hash technique is one out of several ways to speed this up.
*/
static unsigned encodeLZ77(uivector* out, Hash* hash,
                           const unsigned char* in, size_t inpos, size_t insize, unsigned windowsize,
                           unsigned minmatch, unsigned nicematch, unsigned lazymatching)
{
  size_t pos;
  unsigned i, error = 0;
  /*for large window lengths, assume the user wants no compression loss. Otherwise, max hash chain length speedup.*/
  unsigned maxchainlength = windowsize >= 8192 ? windowsize : windowsize / 8;
  unsigned maxlazymatch = windowsize >= 8192 ? MAX_SUPPORTED_DEFLATE_LENGTH : 64;

  unsigned usezeros = 1; /*not sure if setting it to false for windowsize < 8192 is better or worse*/
  unsigned numzeros = 0;

  unsigned offset; /*the offset represents the distance in LZ77 terminology*/
  unsigned length;
  unsigned lazy = 0;
  unsigned lazylength = 0, lazyoffset = 0;
  unsigned hashval;
  unsigned current_offset, current_length;
  unsigned prev_offset;
  const unsigned char *lastptr, *foreptr, *backptr;
  unsigned hashpos;

  if(windowsize == 0 || windowsize > 32768) return 60; /*error: windowsize smaller/larger than allowed*/
  if((windowsize & (windowsize - 1)) != 0) return 90; /*error: must be power of two*/

  if(nicematch > MAX_SUPPORTED_DEFLATE_LENGTH) nicematch = MAX_SUPPORTED_DEFLATE_LENGTH;

  for(pos = inpos; pos < insize; ++pos)
  {
    size_t wpos = pos & (windowsize - 1); /*position for in 'circular' hash buffers*/
    unsigned chainlength = 0;

    hashval = getHash(in, insize, pos);

    if(usezeros && hashval == 0)
    {
      if(numzeros == 0) numzeros = countZeros(in, insize, pos);
      else if(pos + numzeros > insize || in[pos + numzeros - 1] != 0) --numzeros;
    }
    else
    {
      numzeros = 0;
    }

    updateHashChain(hash, wpos, hashval, numzeros);

    /*the length and offset found for the current position*/
    length = 0;
    offset = 0;

    hashpos = hash->chain[wpos];

    lastptr = &in[insize < pos + MAX_SUPPORTED_DEFLATE_LENGTH ? insize : pos + MAX_SUPPORTED_DEFLATE_LENGTH];

    /*search for the longest string*/
    prev_offset = 0;
    for(;;)
    {
      if(chainlength++ >= maxchainlength) break;
      current_offset = (unsigned)(hashpos <= wpos ? wpos - hashpos : wpos - hashpos + windowsize);

      if(current_offset < prev_offset) break; /*stop when went completely around the circular buffer*/
      prev_offset = current_offset;
      if(current_offset > 0)
      {
        /*test the next characters*/
        foreptr = &in[pos];
        backptr = &in[pos - current_offset];

        /*common case in PNGs is lots of zeros. Quickly skip over them as a speedup*/
        if(numzeros >= 3)
        {
          unsigned skip = hash->zeros[hashpos];
          if(skip > numzeros) skip = numzeros;
          backptr += skip;
          foreptr += skip;
        }

        while(foreptr != lastptr && *backptr == *foreptr) /*maximum supported length by deflate is max length*/
        {
          ++backptr;
          ++foreptr;
        }
        current_length = (unsigned)(foreptr - &in[pos]);

        if(current_length > length)
        {
          length = current_length; /*the longest length*/
          offset = current_offset; /*the offset that is related to this longest length*/
          /*jump out once a length of max length is found (speed gain). This also jumps
          out if length is MAX_SUPPORTED_DEFLATE_LENGTH*/
          if(current_length >= nicematch) break;
        }
      }

      if(hashpos == hash->chain[hashpos]) break;

      if(numzeros >= 3 && length > numzeros)
      {
        hashpos = hash->chainz[hashpos];
        if(hash->zeros[hashpos] != numzeros) break;
      }
      else
      {
        hashpos = hash->chain[hashpos];
        /*outdated hash value, happens if particular value was not encountered in whole last window*/
        if(hash->val[hashpos] != (int)hashval) break;
      }
    }

    if(lazymatching)
    {
      if(!lazy && length >= 3 && length <= maxlazymatch && length < MAX_SUPPORTED_DEFLATE_LENGTH)
      {
        lazy = 1;
        lazylength = length;
        lazyoffset = offset;
        continue; /*try the next byte*/
      }
      if(lazy)
      {
        lazy = 0;
        if(pos == 0) ERROR_BREAK(81);
        if(length > lazylength + 1)
        {
          /*push the previous character as literal*/
          if(!uivector_push_back(out, in[pos - 1])) ERROR_BREAK(83 /*alloc fail*/);
        }
        else
        {
          length = lazylength;
          offset = lazyoffset;
          hash->head[hashval] = -1; /*the same hashchain update will be done, this ensures no wrong alteration*/
          hash->headz[numzeros] = -1; /*idem*/
          --pos;
        }
      }
    }
    if(length >= 3 && offset > windowsize) ERROR_BREAK(86 /*too big (or overflown negative) offset*/);

    /*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_BREAK(83 /*alloc fail*/);
    }
    else if(length < minmatch || (length == 3 && offset > 4096))
    {
      /*compensate for the fact that longer offsets have more extra bits, a
      length of only 3 may be not worth it then*/
      if(!uivector_push_back(out, in[pos])) ERROR_BREAK(83 /*alloc fail*/);
    }
    else
    {
      addLengthDistance(out, length, offset);
      for(i = 1; i < length; ++i)
      {
        ++pos;
        wpos = pos & (windowsize - 1);
        hashval = getHash(in, insize, pos);
        if(usezeros && hashval == 0)
        {
          if(numzeros == 0) numzeros = countZeros(in, insize, pos);
          else if(pos + numzeros > insize || in[pos + numzeros - 1] != 0) --numzeros;
        }
        else
        {
          numzeros = 0;
        }
        updateHashChain(hash, wpos, hashval, numzeros);
      }
    }
  } /*end of the loop through each character of input*/

  return error;
}

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

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 + 65534) / 65535;
  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 & 255));
    ucvector_push_back(out, (unsigned char)(LEN >> 8));
    ucvector_push_back(out, (unsigned char)(NLEN & 255));
    ucvector_push_back(out, (unsigned char)(NLEN >> 8));

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

  return 0;
}

/*
write the lz77-encoded data, which has lit, len and dist codes, to compressed stream using huffman trees.
tree_ll: the tree for lit and len codes.
tree_d: the tree for distance codes.
*/
static void writeLZ77data(size_t* bp, ucvector* out, const uivector* lz77_encoded,
                          const HuffmanTree* tree_ll, const HuffmanTree* tree_d)
{
  size_t i = 0;
  for(i = 0; i != lz77_encoded->size; ++i)
  {
    unsigned val = lz77_encoded->data[i];
    addHuffmanSymbol(bp, out, HuffmanTree_getCode(tree_ll, val), HuffmanTree_getLength(tree_ll, 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(tree_d, distance_code),
                       HuffmanTree_getLength(tree_d, distance_code));
      addBitsToStream(bp, out, distance_extra_bits, n_distance_extra_bits);
    }
  }
}

/*Deflate for a block of type "dynamic", that is, with freely, optimally, created huffman trees*/
static unsigned deflateDynamic(ucvector* out, size_t* bp, Hash* hash,
                               const unsigned char* data, size_t datapos, size_t dataend,
                               const LodePNGCompressSettings* settings, unsigned final)
{
  unsigned error = 0;

  /*
  A block is compressed as follows: The PNG data is lz77 encoded, resulting in
  literal bytes and length/distance pairs. This is then huffman compressed with
  two huffman trees. One huffman tree is used for the lit and len values ("ll"),
  another huffman tree is used for the dist values ("d"). These two trees are
  stored using their code lengths, and to compress even more these code lengths
  are also run-length encoded and huffman compressed. This gives a huffman tree
  of code lengths "cl". The code lenghts used to describe this third tree are
  the code length code lengths ("clcl").
  */

  /*The lz77 encoded data, represented with integers since there will also be length and distance codes in it*/
  uivector lz77_encoded;
  HuffmanTree tree_ll; /*tree for lit,len values*/
  HuffmanTree tree_d; /*tree for distance codes*/
  HuffmanTree tree_cl; /*tree for encoding the code lengths representing tree_ll and tree_d*/
  uivector frequencies_ll; /*frequency of lit,len codes*/
  uivector frequencies_d; /*frequency of dist codes*/
  uivector frequencies_cl; /*frequency of code length codes*/
  uivector bitlen_lld; /*lit,len,dist code lenghts (int bits), literally (without repeat codes).*/
  uivector bitlen_lld_e; /*bitlen_lld encoded with repeat codes (this is a rudemtary run length compression)*/
  /*bitlen_cl is the code length code lengths ("clcl"). The bit lengths of codes to represent tree_cl
  (these are written as is in the file, it would be crazy to compress these using yet another huffman
  tree that needs to be represented by yet another set of code lengths)*/
  uivector bitlen_cl;
  size_t datasize = dataend - datapos;

  /*
  Due to the huffman compression of huffman tree representations ("two levels"), there are some anologies:
  bitlen_lld is to tree_cl what data is to tree_ll and tree_d.
  bitlen_lld_e is to bitlen_lld what lz77_encoded is to data.
  bitlen_cl is to bitlen_lld_e what bitlen_lld is to lz77_encoded.
  */

  unsigned BFINAL = final;
  size_t numcodes_ll, numcodes_d, i;
  unsigned HLIT, HDIST, HCLEN;

  uivector_init(&lz77_encoded);
  HuffmanTree_init(&tree_ll);
  HuffmanTree_init(&tree_d);
  HuffmanTree_init(&tree_cl);
  uivector_init(&frequencies_ll);
  uivector_init(&frequencies_d);
  uivector_init(&frequencies_cl);
  uivector_init(&bitlen_lld);
  uivector_init(&bitlen_lld_e);
  uivector_init(&bitlen_cl);

  /*This while loop never loops due to a break at the end, it is here to
  allow breaking out of it to the cleanup phase on error conditions.*/
  while(!error)
  {
    if(settings->use_lz77)
    {
      error = encodeLZ77(&lz77_encoded, hash, data, datapos, dataend, settings->windowsize,
                         settings->minmatch, settings->nicematch, settings->lazymatching);
      if(error) break;
    }
    else
    {
      if(!uivector_resize(&lz77_encoded, datasize)) ERROR_BREAK(83 /*alloc fail*/);
      for(i = datapos; i < dataend; ++i) lz77_encoded.data[i - datapos] = data[i]; /*no LZ77, but still will be Huffman compressed*/
    }

    if(!uivector_resizev(&frequencies_ll, 286, 0)) ERROR_BREAK(83 /*alloc fail*/);
    if(!uivector_resizev(&frequencies_d, 30, 0)) ERROR_BREAK(83 /*alloc fail*/);

    /*Count the frequencies of lit, len and dist codes*/
    for(i = 0; i != lz77_encoded.size; ++i)
    {
      unsigned symbol = lz77_encoded.data[i];
      ++frequencies_ll.data[symbol];
      if(symbol > 256)
      {
        unsigned dist = lz77_encoded.data[i + 2];
        ++frequencies_d.data[dist];
        i += 3;
      }
    }
    frequencies_ll.data[256] = 1; /*there will be exactly 1 end code, at the end of the block*/

    /*Make both huffman trees, one for the lit and len codes, one for the dist codes*/
    error = HuffmanTree_makeFromFrequencies(&tree_ll, frequencies_ll.data, 257, frequencies_ll.size, 15);
    if(error) break;
    /*2, not 1, is chosen for mincodes: some buggy PNG decoders require at least 2 symbols in the dist tree*/
    error = HuffmanTree_makeFromFrequencies(&tree_d, frequencies_d.data, 2, frequencies_d.size, 15);
    if(error) break;

    numcodes_ll = tree_ll.numcodes; if(numcodes_ll > 286) numcodes_ll = 286;
    numcodes_d = tree_d.numcodes; if(numcodes_d > 30) numcodes_d = 30;
    /*store the code lengths of both generated trees in bitlen_lld*/
    for(i = 0; i != numcodes_ll; ++i) uivector_push_back(&bitlen_lld, HuffmanTree_getLength(&tree_ll, (unsigned)i));
    for(i = 0; i != numcodes_d; ++i) uivector_push_back(&bitlen_lld, HuffmanTree_getLength(&tree_d, (unsigned)i));

    /*run-length compress bitlen_ldd into bitlen_lld_e by using repeat codes 16 (copy length 3-6 times),
    17 (3-10 zeroes), 18 (11-138 zeroes)*/
    for(i = 0; i != (unsigned)bitlen_lld.size; ++i)
    {
      unsigned j = 0; /*amount of repititions*/
      while(i + j + 1 < (unsigned)bitlen_lld.size && bitlen_lld.data[i + j + 1] == bitlen_lld.data[i]) ++j;

      if(bitlen_lld.data[i] == 0 && j >= 2) /*repeat code for zeroes*/
      {
        ++j; /*include the first zero*/
        if(j <= 10) /*repeat code 17 supports max 10 zeroes*/
        {
          uivector_push_back(&bitlen_lld_e, 17);
          uivector_push_back(&bitlen_lld_e, j - 3);
        }
        else /*repeat code 18 supports max 138 zeroes*/
        {
          if(j > 138) j = 138;
          uivector_push_back(&bitlen_lld_e, 18);
          uivector_push_back(&bitlen_lld_e, j - 11);
        }
        i += (j - 1);
      }
      else if(j >= 3) /*repeat code for value other than zero*/
      {
        size_t k;
        unsigned num = j / 6, rest = j % 6;
        uivector_push_back(&bitlen_lld_e, bitlen_lld.data[i]);
        for(k = 0; k < num; ++k)
        {
          uivector_push_back(&bitlen_lld_e, 16);
          uivector_push_back(&bitlen_lld_e, 6 - 3);
        }
        if(rest >= 3)
        {
          uivector_push_back(&bitlen_lld_e, 16);
          uivector_push_back(&bitlen_lld_e, rest - 3);
        }
        else j -= rest;
        i += j;
      }
      else /*too short to benefit from repeat code*/
      {
        uivector_push_back(&bitlen_lld_e, bitlen_lld.data[i]);
      }
    }

    /*generate tree_cl, the huffmantree of huffmantrees*/

    if(!uivector_resizev(&frequencies_cl, NUM_CODE_LENGTH_CODES, 0)) ERROR_BREAK(83 /*alloc fail*/);
    for(i = 0; i != bitlen_lld_e.size; ++i)
    {
      ++frequencies_cl.data[bitlen_lld_e.data[i]];
      /*after a repeat code come the bits that specify the number of repetitions,
      those don't need to be in the frequencies_cl calculation*/
      if(bitlen_lld_e.data[i] >= 16) ++i;
    }

    error = HuffmanTree_makeFromFrequencies(&tree_cl, frequencies_cl.data,
                                            frequencies_cl.size, frequencies_cl.size, 7);
    if(error) break;

    if(!uivector_resize(&bitlen_cl, tree_cl.numcodes)) ERROR_BREAK(83 /*alloc fail*/);
    for(i = 0; i != tree_cl.numcodes; ++i)
    {
      /*lenghts of code length tree is in the order as specified by deflate*/
      bitlen_cl.data[i] = HuffmanTree_getLength(&tree_cl, CLCL_ORDER[i]);
    }
    while(bitlen_cl.data[bitlen_cl.size - 1] == 0 && bitlen_cl.size > 4)
    {
      /*remove zeros at the end, but minimum size must be 4*/
      if(!uivector_resize(&bitlen_cl, bitlen_cl.size - 1)) ERROR_BREAK(83 /*alloc fail*/);
    }
    if(error) break;

    /*
    Write everything into the output

    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 lenghts 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)
    */

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

    /*write the HLIT, HDIST and HCLEN values*/
    HLIT = (unsigned)(numcodes_ll - 257);
    HDIST = (unsigned)(numcodes_d - 1);
    HCLEN = (unsigned)bitlen_cl.size - 4;
    /*trim zeroes for HCLEN. HLIT and HDIST were already trimmed at tree creation*/
    while(!bitlen_cl.data[HCLEN + 4 - 1] && HCLEN > 0) --HCLEN;
    addBitsToStream(bp, out, HLIT, 5);
    addBitsToStream(bp, out, HDIST, 5);
    addBitsToStream(bp, out, HCLEN, 4);

    /*write the code lenghts of the code length alphabet*/
    for(i = 0; i != HCLEN + 4; ++i) addBitsToStream(bp, out, bitlen_cl.data[i], 3);

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

    /*write the compressed data symbols*/
    writeLZ77data(bp, out, &lz77_encoded, &tree_ll, &tree_d);
    /*error: the length of the end code 256 must be larger than 0*/
    if(HuffmanTree_getLength(&tree_ll, 256) == 0) ERROR_BREAK(64);

    /*write the end code*/
    addHuffmanSymbol(bp, out, HuffmanTree_getCode(&tree_ll, 256), HuffmanTree_getLength(&tree_ll, 256));

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

  /*cleanup*/
  uivector_cleanup(&lz77_encoded);
  HuffmanTree_cleanup(&tree_ll);
  HuffmanTree_cleanup(&tree_d);
  HuffmanTree_cleanup(&tree_cl);
  uivector_cleanup(&frequencies_ll);
  uivector_cleanup(&frequencies_d);
  uivector_cleanup(&frequencies_cl);
  uivector_cleanup(&bitlen_lld_e);
  uivector_cleanup(&bitlen_lld);
  uivector_cleanup(&bitlen_cl);

  return error;
}

static unsigned deflateFixed(ucvector* out, size_t* bp, Hash* hash,
                             const unsigned char* data,
                             size_t datapos, size_t dataend,
                             const LodePNGCompressSettings* settings, unsigned final)
{
  HuffmanTree tree_ll; /*tree for literal values and length codes*/
  HuffmanTree tree_d; /*tree for distance codes*/

  unsigned BFINAL = final;
  unsigned error = 0;
  size_t i;

  HuffmanTree_init(&tree_ll);
  HuffmanTree_init(&tree_d);

  generateFixedLitLenTree(&tree_ll);
  generateFixedDistanceTree(&tree_d);

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

  if(settings->use_lz77) /*LZ77 encoded*/
  {
    uivector lz77_encoded;
    uivector_init(&lz77_encoded);
    error = encodeLZ77(&lz77_encoded, hash, data, datapos, dataend, settings->windowsize,
                       settings->minmatch, settings->nicematch, settings->lazymatching);
    if(!error) writeLZ77data(bp, out, &lz77_encoded, &tree_ll, &tree_d);
    uivector_cleanup(&lz77_encoded);
  }
  else /*no LZ77, but still will be Huffman compressed*/
  {
    for(i = datapos; i < dataend; ++i)
    {
      addHuffmanSymbol(bp, out, HuffmanTree_getCode(&tree_ll, data[i]), HuffmanTree_getLength(&tree_ll, data[i]));
    }
  }
  /*add END code*/
  if(!error) addHuffmanSymbol(bp, out, HuffmanTree_getCode(&tree_ll, 256), HuffmanTree_getLength(&tree_ll, 256));

  /*cleanup*/
  HuffmanTree_cleanup(&tree_ll);
  HuffmanTree_cleanup(&tree_d);

  return error;
}

static unsigned lodepng_deflatev(ucvector* out, const unsigned char* in, size_t insize,
                                 const LodePNGCompressSettings* settings)
{
  unsigned error = 0;
  size_t i, blocksize, numdeflateblocks;
  size_t bp = 0; /*the bit pointer*/
  Hash hash;

  if(settings->btype > 2) return 61;
  else if(settings->btype == 0) return deflateNoCompression(out, in, insize);
  else if(settings->btype == 1) blocksize = insize;
  else /*if(settings->btype == 2)*/
  {
    /*on PNGs, deflate blocks of 65-262k seem to give most dense encoding*/
    blocksize = insize / 8 + 8;
    if(blocksize < 65536) blocksize = 65536;
    if(blocksize > 262144) blocksize = 262144;
  }

  numdeflateblocks = (insize + blocksize - 1) / blocksize;
  if(numdeflateblocks == 0) numdeflateblocks = 1;

  error = hash_init(&hash, settings->windowsize);
  if(error) return error;

  for(i = 0; i != numdeflateblocks && !error; ++i)
  {
    unsigned final = (i == numdeflateblocks - 1);
    size_t start = i * blocksize;
    size_t end = start + blocksize;
    if(end > insize) end = insize;

    if(settings->btype == 1) error = deflateFixed(out, &bp, &hash, in, start, end, settings, final);
    else if(settings->btype == 2) error = deflateDynamic(out, &bp, &hash, in, start, end, settings, final);
  }

  hash_cleanup(&hash);

  return error;
}

unsigned lodepng_deflate(unsigned char** out, size_t* outsize,
                         const unsigned char* in, size_t insize,
                         const LodePNGCompressSettings* settings)
{
  unsigned error;
  ucvector v;
  ucvector_init_buffer(&v, *out, *outsize);
  error = lodepng_deflatev(&v, in, insize, settings);
  *out = v.data;
  *outsize = v.size;
  return error;
}

static unsigned deflate(unsigned char** out, size_t* outsize,
                        const unsigned char* in, size_t insize,
                        const LodePNGCompressSettings* settings)
{
  if(settings->custom_deflate)
  {
    return settings->custom_deflate(out, outsize, in, insize, settings);
  }
  else
  {
    return lodepng_deflate(out, outsize, in, insize, settings);
  }
}

#endif /*LODEPNG_COMPILE_DECODER*/

/* ////////////////////////////////////////////////////////////////////////// */
/* / 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 5552 sums can be done before the sums overflow, saving a lot of module divisions*/
    unsigned amount = len > 5552 ? 5552 : len;
    len -= amount;
    while(amount > 0)
    {
      s1 += (*data++);
      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);
}

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

#ifdef LODEPNG_COMPILE_DECODER

unsigned lodepng_zlib_decompress(unsigned char** out, size_t* outsize, const unsigned char* in,
                                 size_t insize, const LodePNGDecompressSettings* settings)
{
  unsigned error = 0;
  unsigned CM, CINFO, FDICT;

  if(insize < 2) return 53; /*error, size of zlib data too small*/
  /*read information from zlib header*/
  if((in[0] * 256 + in[1]) % 31 != 0)
  {
    /*error: 256 * in[0] + in[1] must be a multiple of 31, the FCHECK value is supposed to be made that way*/
    return 24;
  }

  CM = in[0] & 15;
  CINFO = (in[0] >> 4) & 15;
  /*FCHECK = in[1] & 31;*/ /*FCHECK is already tested above*/
  FDICT = (in[1] >> 5) & 1;
  /*FLEVEL = (in[1] >> 6) & 3;*/ /*FLEVEL is not used here*/

  if(CM != 8 || CINFO > 7)
  {
    /*error: only compression method 8: inflate with sliding window of 32k is supported by the PNG spec*/
    return 25;
  }
  if(FDICT != 0)
  {
    /*error: the specification of PNG says about the zlib stream:
      "The additional flags shall not specify a preset dictionary."*/
    return 26;
  }

  error = inflate(out, outsize, in + 2, insize - 2, settings);
  if(error) return error;

  if(!settings->ignore_adler32)
  {
    unsigned ADLER32 = lodepng_read32bitInt(&in[insize - 4]);
    unsigned checksum = adler32(*out, (unsigned)(*outsize));
    if(checksum != ADLER32) return 58; /*error, adler checksum not correct, data must be corrupted*/
  }

  return 0; /*no error*/
}

static unsigned zlib_decompress(unsigned char** out, size_t* outsize, const unsigned char* in,
                                size_t insize, const LodePNGDecompressSettings* settings)
{
  if(settings->custom_zlib)
  {
    return settings->custom_zlib(out, outsize, in, insize, settings);
  }
  else
  {
    return lodepng_zlib_decompress(out, outsize, in, insize, settings);
  }
}

#endif /*LODEPNG_COMPILE_DECODER*/

#ifdef LODEPNG_COMPILE_ENCODER

unsigned lodepng_zlib_compress(unsigned char** out, size_t* outsize, const unsigned char* in,
                               size_t insize, const LodePNGCompressSettings* 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 outv;
  size_t i;
  unsigned error;
  unsigned char* deflatedata = 0;
  size_t deflatesize = 0;

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

  ucvector_push_back(&outv, (unsigned char)(CMFFLG >> 8));
  ucvector_push_back(&outv, (unsigned char)(CMFFLG & 255));

  error = deflate(&deflatedata, &deflatesize, in, insize, settings);

  if(!error)
  {
    unsigned ADLER32 = adler32(in, (unsigned)insize);
    for(i = 0; i != deflatesize; ++i) ucvector_push_back(&outv, deflatedata[i]);
    lodepng_free(deflatedata);
    lodepng_add32bitInt(&outv, ADLER32);
  }

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

  return error;
}

/* compress using the default or custom zlib function */
static unsigned zlib_compress(unsigned char** out, size_t* outsize, const unsigned char* in,
                              size_t insize, const LodePNGCompressSettings* settings)
{
  if(settings->custom_zlib)
  {
    return settings->custom_zlib(out, outsize, in, insize, settings);
  }
  else
  {
    return lodepng_zlib_compress(out, outsize, in, insize, settings);
  }
}

#endif /*LODEPNG_COMPILE_ENCODER*/

#else /*no LODEPNG_COMPILE_ZLIB*/

#ifdef LODEPNG_COMPILE_DECODER
static unsigned zlib_decompress(unsigned char** out, size_t* outsize, const unsigned char* in,
                                size_t insize, const LodePNGDecompressSettings* settings)
{
  if(!settings->custom_zlib) return 87; /*no custom zlib function provided */
  return settings->custom_zlib(out, outsize, in, insize, settings);
}
#endif /*LODEPNG_COMPILE_DECODER*/
#ifdef LODEPNG_COMPILE_ENCODER
static unsigned zlib_compress(unsigned char** out, size_t* outsize, const unsigned char* in,
                              size_t insize, const LodePNGCompressSettings* settings)
{
  if(!settings->custom_zlib) return 87; /*no custom zlib function provided */
  return settings->custom_zlib(out, outsize, in, insize, settings);
}
#endif /*LODEPNG_COMPILE_ENCODER*/

#endif /*LODEPNG_COMPILE_ZLIB*/

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

#ifdef LODEPNG_COMPILE_ENCODER

/*this is a good tradeoff between speed and compression ratio*/
#define DEFAULT_WINDOWSIZE 2048

void lodepng_compress_settings_init(LodePNGCompressSettings* settings)
{
  /*compress with dynamic huffman tree (not in the mathematical sense, just not the predefined one)*/
  settings->btype = 2;
  settings->use_lz77 = 1;
  settings->windowsize = DEFAULT_WINDOWSIZE;
  settings->minmatch = 3;
  settings->nicematch = 128;
  settings->lazymatching = 1;

  settings->custom_zlib = 0;
  settings->custom_deflate = 0;
  settings->custom_context = 0;
}

const LodePNGCompressSettings lodepng_default_compress_settings = {2, 1, DEFAULT_WINDOWSIZE, 3, 128, 1, 0, 0, 0};


#endif /*LODEPNG_COMPILE_ENCODER*/

#ifdef LODEPNG_COMPILE_DECODER

void lodepng_decompress_settings_init(LodePNGDecompressSettings* settings)
{
  settings->ignore_adler32 = 0;

  settings->custom_zlib = 0;
  settings->custom_inflate = 0;
  settings->custom_context = 0;
}

const LodePNGDecompressSettings lodepng_default_decompress_settings = {0, 0, 0, 0};

#endif /*LODEPNG_COMPILE_DECODER*/

/* ////////////////////////////////////////////////////////////////////////// */
/* ////////////////////////////////////////////////////////////////////////// */
/* // End of Zlib related code. Begin of PNG related code.                 // */
/* ////////////////////////////////////////////////////////////////////////// */
/* ////////////////////////////////////////////////////////////////////////// */

#ifdef LODEPNG_COMPILE_PNG

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


#ifndef LODEPNG_NO_COMPILE_CRC
/* CRC polynomial: 0xedb88320 */
static unsigned lodepng_crc32_table[256] = {
           0u, 1996959894u, 3993919788u, 2567524794u,  124634137u, 1886057615u, 3915621685u, 2657392035u,
   249268274u, 2044508324u, 3772115230u, 2547177864u,  162941995u, 2125561021u, 3887607047u, 2428444049u,
   498536548u, 1789927666u, 4089016648u, 2227061214u,  450548861u, 1843258603u, 4107580753u, 2211677639u,
   325883990u, 1684777152u, 4251122042u, 2321926636u,  335633487u, 1661365465u, 4195302755u, 2366115317u,
   997073096u, 1281953886u, 3579855332u, 2724688242u, 1006888145u, 1258607687u, 3524101629u, 2768942443u,
   901097722u, 1119000684u, 3686517206u, 2898065728u,  853044451u, 1172266101u, 3705015759u, 2882616665u,
   651767980u, 1373503546u, 3369554304u, 3218104598u,  565507253u, 1454621731u, 3485111705u, 3099436303u,
   671266974u, 1594198024u, 3322730930u, 2970347812u,  795835527u, 1483230225u, 3244367275u, 3060149565u,
  1994146192u,   31158534u, 2563907772u, 4023717930u, 1907459465u,  112637215u, 2680153253u, 3904427059u,
  2013776290u,  251722036u, 2517215374u, 3775830040u, 2137656763u,  141376813u, 2439277719u, 3865271297u,
  1802195444u,  476864866u, 2238001368u, 4066508878u, 1812370925u,  453092731u, 2181625025u, 4111451223u,
  1706088902u,  314042704u, 2344532202u, 4240017532u, 1658658271u,  366619977u, 2362670323u, 4224994405u,
  1303535960u,  984961486u, 2747007092u, 3569037538u, 1256170817u, 1037604311u, 2765210733u, 3554079995u,
  1131014506u,  879679996u, 2909243462u, 3663771856u, 1141124467u,  855842277u, 2852801631u, 3708648649u,
  1342533948u,  654459306u, 3188396048u, 3373015174u, 1466479909u,  544179635u, 3110523913u, 3462522015u,
  1591671054u,  702138776u, 2966460450u, 3352799412u, 1504918807u,  783551873u, 3082640443u, 3233442989u,
  3988292384u, 2596254646u,   62317068u, 1957810842u, 3939845945u, 2647816111u,   81470997u, 1943803523u,
  3814918930u, 2489596804u,  225274430u, 2053790376u, 3826175755u, 2466906013u,  167816743u, 2097651377u,
  4027552580u, 2265490386u,  503444072u, 1762050814u, 4150417245u, 2154129355u,  426522225u, 1852507879u,
  4275313526u, 2312317920u,  282753626u, 1742555852u, 4189708143u, 2394877945u,  397917763u, 1622183637u,
  3604390888u, 2714866558u,  953729732u, 1340076626u, 3518719985u, 2797360999u, 1068828381u, 1219638859u,
  3624741850u, 2936675148u,  906185462u, 1090812512u, 3747672003u, 2825379669u,  829329135u, 1181335161u,
  3412177804u, 3160834842u,  628085408u, 1382605366u, 3423369109u, 3138078467u,  570562233u, 1426400815u,
  3317316542u, 2998733608u,  733239954u, 1555261956u, 3268935591u, 3050360625u,  752459403u, 1541320221u,
  2607071920u, 3965973030u, 1969922972u,   40735498u, 2617837225u, 3943577151u, 1913087877u,   83908371u,
  2512341634u, 3803740692u, 2075208622u,  213261112u, 2463272603u, 3855990285u, 2094854071u,  198958881u,
  2262029012u, 4057260610u, 1759359992u,  534414190u, 2176718541u, 4139329115u, 1873836001u,  414664567u,
  2282248934u, 4279200368u, 1711684554u,  285281116u, 2405801727u, 4167216745u, 1634467795u,  376229701u,
  2685067896u, 3608007406u, 1308918612u,  956543938u, 2808555105u, 3495958263u, 1231636301u, 1047427035u,
  2932959818u, 3654703836u, 1088359270u,  936918000u, 2847714899u, 3736837829u, 1202900863u,  817233897u,
  3183342108u, 3401237130u, 1404277552u,  615818150u, 3134207493u, 3453421203u, 1423857449u,  601450431u,
  3009837614u, 3294710456u, 1567103746u,  711928724u, 3020668471u, 3272380065u, 1510334235u,  755167117u
};

/*Return the CRC of the bytes buf[0..len-1].*/
unsigned lodepng_crc32(const unsigned char* data, size_t length)
{
  unsigned r = 0xffffffffu;
  size_t i;
  for(i = 0; i < length; ++i)
  {
    r = lodepng_crc32_table[(r ^ data[i]) & 0xff] ^ (r >> 8);
  }
  return r ^ 0xffffffffu;
}
#else /* !LODEPNG_NO_COMPILE_CRC */
unsigned lodepng_crc32(const unsigned char* data, size_t length);
#endif /* !LODEPNG_NO_COMPILE_CRC */

/* ////////////////////////////////////////////////////////////////////////// */
/* / 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 = 0 ; i < nbits; ++i)
  {
    result <<= 1;
    result |= (unsigned)readBitFromReversedStream(bitpointer, bitstream);
  }
  return result;
}

#ifdef LODEPNG_COMPILE_DECODER
static void setBitOfReversedStream0(size_t* bitpointer, unsigned char* bitstream, unsigned char bit)
{
  /*the current bit in bitstream must be 0 for this to work*/
  if(bit)
  {
    /*earlier bit of huffman code is in a lesser significant bit of an earlier byte*/
    bitstream[(*bitpointer) >> 3] |= (bit << (7 - ((*bitpointer) & 0x7)));
  }
  ++(*bitpointer);
}
#endif /*LODEPNG_COMPILE_DECODER*/

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);
}

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

unsigned lodepng_chunk_length(const unsigned char* chunk)
{
  return lodepng_read32bitInt(&chunk[0]);
}

void lodepng_chunk_type(char type[5], const unsigned char* chunk)
{
  unsigned i;
  for(i = 0; i != 4; ++i) type[i] = (char)chunk[4 + i];
  type[4] = 0; /*null termination char*/
}

unsigned char lodepng_chunk_type_equals(const unsigned char* chunk, const char* type)
{
  if(strlen(type) != 4) return 0;
  return (chunk[4] == type[0] && chunk[5] == type[1] && chunk[6] == type[2] && chunk[7] == type[3]);
}

unsigned char lodepng_chunk_ancillary(const unsigned char* chunk)
{
  return((chunk[4] & 32) != 0);
}

unsigned char lodepng_chunk_private(const unsigned char* chunk)
{
  return((chunk[6] & 32) != 0);
}

unsigned char lodepng_chunk_safetocopy(const unsigned char* chunk)
{
  return((chunk[7] & 32) != 0);
}

unsigned char* lodepng_chunk_data(unsigned char* chunk)
{
  return &chunk[8];
}

const unsigned char* lodepng_chunk_data_const(const unsigned char* chunk)
{
  return &chunk[8];
}

unsigned lodepng_chunk_check_crc(const unsigned char* chunk)
{
  unsigned length = lodepng_chunk_length(chunk);
  unsigned CRC = lodepng_read32bitInt(&chunk[length + 8]);
  /*the CRC is taken of the data and the 4 chunk type letters, not the length*/
  unsigned checksum = lodepng_crc32(&chunk[4], length + 4);
  if(CRC != checksum) return 1;
  else return 0;
}

void lodepng_chunk_generate_crc(unsigned char* chunk)
{
  unsigned length = lodepng_chunk_length(chunk);
  unsigned CRC = lodepng_crc32(&chunk[4], length + 4);
  lodepng_set32bitInt(chunk + 8 + length, CRC);
}

unsigned char* lodepng_chunk_next(unsigned char* chunk)
{
  unsigned total_chunk_length = lodepng_chunk_length(chunk) + 12;
  return &chunk[total_chunk_length];
}

const unsigned char* lodepng_chunk_next_const(const unsigned char* chunk)
{
  unsigned total_chunk_length = lodepng_chunk_length(chunk) + 12;
  return &chunk[total_chunk_length];
}

unsigned lodepng_chunk_append(unsigned char** out, size_t* outlength, const unsigned char* chunk)
{
  unsigned i;
  unsigned total_chunk_length = lodepng_chunk_length(chunk) + 12;
  unsigned char *chunk_start, *new_buffer;
  size_t new_length = (*outlength) + total_chunk_length;
  if(new_length < total_chunk_length || new_length < (*outlength)) return 77; /*integer overflow happened*/

  new_buffer = (unsigned char*)lodepng_realloc(*out, new_length);
  if(!new_buffer) return 83; /*alloc fail*/
  (*out) = new_buffer;
  (*outlength) = new_length;
  chunk_start = &(*out)[new_length - total_chunk_length];

  for(i = 0; i != total_chunk_length; ++i) chunk_start[i] = chunk[i];

  return 0;
}

unsigned lodepng_chunk_create(unsigned char** out, size_t* outlength, unsigned length,
                              const char* type, const unsigned char* data)
{
  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*)lodepng_realloc(*out, new_length);
  if(!new_buffer) return 83; /*alloc fail*/
  (*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] = (unsigned char)type[0];
  chunk[5] = (unsigned char)type[1];
  chunk[6] = (unsigned char)type[2];
  chunk[7] = (unsigned char)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(LodePNGColorType 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(LodePNGColorType 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 lodepng_get_bpp_lct(LodePNGColorType colortype, unsigned bitdepth)
{
  /*bits per pixel is amount of channels * bits per channel*/
  return getNumColorChannels(colortype) * bitdepth;
}

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

void lodepng_color_mode_init(LodePNGColorMode* info)
{
  info->key_defined = 0;
  info->key_r = info->key_g = info->key_b = 0;
  info->colortype = LCT_RGBA;
  info->bitdepth = 8;
  info->palette = 0;
  info->palettesize = 0;
}

void lodepng_color_mode_cleanup(LodePNGColorMode* info)
{
  lodepng_palette_clear(info);
}

unsigned lodepng_color_mode_copy(LodePNGColorMode* dest, const LodePNGColorMode* source)
{
  size_t i;
  lodepng_color_mode_cleanup(dest);
  *dest = *source;
  if(source->palette)
  {
    dest->palette = (unsigned char*)lodepng_malloc(1024);
    if(!dest->palette && source->palettesize) return 83; /*alloc fail*/
    for(i = 0; i != source->palettesize * 4; ++i) dest->palette[i] = source->palette[i];
  }
  return 0;
}

static int lodepng_color_mode_equal(const LodePNGColorMode* a, const LodePNGColorMode* b)
{
  size_t i;
  if(a->colortype != b->colortype) return 0;
  if(a->bitdepth != b->bitdepth) return 0;
  if(a->key_defined != b->key_defined) return 0;
  if(a->key_defined)
  {
    if(a->key_r != b->key_r) return 0;
    if(a->key_g != b->key_g) return 0;
    if(a->key_b != b->key_b) return 0;
  }
  if(a->palettesize != b->palettesize) return 0;
  for(i = 0; i != a->palettesize * 4; ++i)
  {
    if(a->palette[i] != b->palette[i]) return 0;
  }
  return 1;
}

void lodepng_palette_clear(LodePNGColorMode* info)
{
  if(info->palette) lodepng_free(info->palette);
  info->palette = 0;
  info->palettesize = 0;
}

unsigned lodepng_palette_add(LodePNGColorMode* 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->palette) /*allocate palette if empty*/
  {
    /*room for 256 colors with 4 bytes each*/
    data = (unsigned char*)lodepng_realloc(info->palette, 1024);
    if(!data) return 83; /*alloc fail*/
    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;
}

unsigned lodepng_get_bpp(const LodePNGColorMode* info)
{
  /*calculate bits per pixel out of colortype and bitdepth*/
  return lodepng_get_bpp_lct(info->colortype, info->bitdepth);
}

unsigned lodepng_get_channels(const LodePNGColorMode* info)
{
  return getNumColorChannels(info->colortype);
}

unsigned lodepng_is_greyscale_type(const LodePNGColorMode* info)
{
  return info->colortype == LCT_GREY || info->colortype == LCT_GREY_ALPHA;
}

unsigned lodepng_is_alpha_type(const LodePNGColorMode* info)
{
  return (info->colortype & 4) != 0; /*4 or 6*/
}

unsigned lodepng_is_palette_type(const LodePNGColorMode* info)
{
  return info->colortype == LCT_PALETTE;
}

unsigned lodepng_has_palette_alpha(const LodePNGColorMode* info)
{
  size_t i;
  for(i = 0; i != info->palettesize; ++i)
  {
    if(info->palette[i * 4 + 3] < 255) return 1;
  }
  return 0;
}

unsigned lodepng_can_have_alpha(const LodePNGColorMode* info)
{
  return info->key_defined
      || lodepng_is_alpha_type(info)
      || lodepng_has_palette_alpha(info);
}

size_t lodepng_get_raw_size_lct(unsigned w, unsigned h, LodePNGColorType colortype, unsigned bitdepth)
{
  size_t bpp = lodepng_get_bpp_lct(colortype, bitdepth);
  size_t n = (size_t)w * (size_t)h;
  return ((n / 8) * bpp) + ((n & 7) * bpp + 7) / 8;
}

size_t lodepng_get_raw_size(unsigned w, unsigned h, const LodePNGColorMode* color)
{
  return lodepng_get_raw_size_lct(w, h, color->colortype, color->bitdepth);
}


#ifdef LODEPNG_COMPILE_PNG
#ifdef LODEPNG_COMPILE_DECODER

/*in an idat chunk, each scanline is a multiple of 8 bits, unlike the lodepng output buffer,
and in addition has one extra byte per line: the filter byte. So this gives a larger
result than lodepng_get_raw_size. */
static size_t lodepng_get_raw_size_idat(unsigned w, unsigned h, const LodePNGColorMode* color)
{
  size_t bpp = lodepng_get_bpp(color);
  /* + 1 for the filter byte, and possibly plus padding bits per line */
  size_t line = ((size_t)(w / 8) * bpp) + 1 + ((w & 7) * bpp + 7) / 8;
  return (size_t)h * line;
}

/* Safely check if multiplying two integers will overflow (no undefined
behavior, compiler removing the code, etc...) and output result. */
static int lodepng_mulofl(size_t a, size_t b, size_t* result)
{
  *result = a * b; /* Unsigned multiplication is well defined and safe in C90 */
  return (a != 0 && *result / a != b);
}

/* Safely check if adding two integers will overflow (no undefined
behavior, compiler removing the code, etc...) and output result. */
static int lodepng_addofl(size_t a, size_t b, size_t* result)
{
  *result = a + b; /* Unsigned addition is well defined and safe in C90 */
  return *result < a;
}

/*Safely checks whether size_t overflow can be caused due to amount of pixels.
This check is overcautious rather than precise. If this check indicates no overflow,
you can safely compute in a size_t (but not an unsigned):
-(size_t)w * (size_t)h * 8
-amount of bytes in IDAT (including filter, padding and Adam7 bytes)
-amount of bytes in raw color model
Returns 1 if overflow possible, 0 if not.
*/
static int lodepng_pixel_overflow(unsigned w, unsigned h,
                                  const LodePNGColorMode* pngcolor, const LodePNGColorMode* rawcolor)
{
  size_t bpp = LODEPNG_MAX(lodepng_get_bpp(pngcolor), lodepng_get_bpp(rawcolor));
  size_t numpixels, total;
  size_t line; /* bytes per line in worst case */

  if(lodepng_mulofl((size_t)w, (size_t)h, &numpixels)) return 1;
  if(lodepng_mulofl(numpixels, 8, &total)) return 1; /* bit pointer with 8-bit color, or 8 bytes per channel color */

  /* Bytes per scanline with the expression "(w / 8) * bpp) + ((w & 7) * bpp + 7) / 8" */
  if(lodepng_mulofl((size_t)(w / 8), bpp, &line)) return 1;
  if(lodepng_addofl(line, ((w & 7) * bpp + 7) / 8, &line)) return 1;

  if(lodepng_addofl(line, 5, &line)) return 1; /* 5 bytes overhead per line: 1 filterbyte, 4 for Adam7 worst case */
  if(lodepng_mulofl(line, h, &total)) return 1; /* Total bytes in worst case */

  return 0; /* no overflow */
}
#endif /*LODEPNG_COMPILE_DECODER*/
#endif /*LODEPNG_COMPILE_PNG*/

#ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS

static void LodePNGUnknownChunks_init(LodePNGInfo* info)
{
  unsigned i;
  for(i = 0; i != 3; ++i) info->unknown_chunks_data[i] = 0;
  for(i = 0; i != 3; ++i) info->unknown_chunks_size[i] = 0;
}

static void LodePNGUnknownChunks_cleanup(LodePNGInfo* info)
{
  unsigned i;
  for(i = 0; i != 3; ++i) lodepng_free(info->unknown_chunks_data[i]);
}

static unsigned LodePNGUnknownChunks_copy(LodePNGInfo* dest, const LodePNGInfo* src)
{
  unsigned i;

  LodePNGUnknownChunks_cleanup(dest);

  for(i = 0; i != 3; ++i)
  {
    size_t j;
    dest->unknown_chunks_size[i] = src->unknown_chunks_size[i];
    dest->unknown_chunks_data[i] = (unsigned char*)lodepng_malloc(src->unknown_chunks_size[i]);
    if(!dest->unknown_chunks_data[i] && dest->unknown_chunks_size[i]) return 83; /*alloc fail*/
    for(j = 0; j < src->unknown_chunks_size[i]; ++j)
    {
      dest->unknown_chunks_data[i][j] = src->unknown_chunks_data[i][j];
    }
  }

  return 0;
}

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

static void LodePNGText_init(LodePNGInfo* info)
{
  info->text_num = 0;
  info->text_keys = NULL;
  info->text_strings = NULL;
}

static void LodePNGText_cleanup(LodePNGInfo* info)
{
  size_t i;
  for(i = 0; i != info->text_num; ++i)
  {
    string_cleanup(&info->text_keys[i]);
    string_cleanup(&info->text_strings[i]);
  }
  lodepng_free(info->text_keys);
  lodepng_free(info->text_strings);
}

static unsigned LodePNGText_copy(LodePNGInfo* dest, const LodePNGInfo* source)
{
  size_t i = 0;
  dest->text_keys = 0;
  dest->text_strings = 0;
  dest->text_num = 0;
  for(i = 0; i != source->text_num; ++i)
  {
    CERROR_TRY_RETURN(lodepng_add_text(dest, source->text_keys[i], source->text_strings[i]));
  }
  return 0;
}

void lodepng_clear_text(LodePNGInfo* info)
{
  LodePNGText_cleanup(info);
}

unsigned lodepng_add_text(LodePNGInfo* info, const char* key, const char* str)
{
  char** new_keys = (char**)(lodepng_realloc(info->text_keys, sizeof(char*) * (info->text_num + 1)));
  char** new_strings = (char**)(lodepng_realloc(info->text_strings, sizeof(char*) * (info->text_num + 1)));
  if(!new_keys || !new_strings)
  {
    lodepng_free(new_keys);
    lodepng_free(new_strings);
    return 83; /*alloc fail*/
  }

  ++info->text_num;
  info->text_keys = new_keys;
  info->text_strings = new_strings;

  string_init(&info->text_keys[info->text_num - 1]);
  string_set(&info->text_keys[info->text_num - 1], key);

  string_init(&info->text_strings[info->text_num - 1]);
  string_set(&info->text_strings[info->text_num - 1], str);

  return 0;
}

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

static void LodePNGIText_init(LodePNGInfo* info)
{
  info->itext_num = 0;
  info->itext_keys = NULL;
  info->itext_langtags = NULL;
  info->itext_transkeys = NULL;
  info->itext_strings = NULL;
}

static void LodePNGIText_cleanup(LodePNGInfo* info)
{
  size_t i;
  for(i = 0; i != info->itext_num; ++i)
  {
    string_cleanup(&info->itext_keys[i]);
    string_cleanup(&info->itext_langtags[i]);
    string_cleanup(&info->itext_transkeys[i]);
    string_cleanup(&info->itext_strings[i]);
  }
  lodepng_free(info->itext_keys);
  lodepng_free(info->itext_langtags);
  lodepng_free(info->itext_transkeys);
  lodepng_free(info->itext_strings);
}

static unsigned LodePNGIText_copy(LodePNGInfo* dest, const LodePNGInfo* source)
{
  size_t i = 0;
  dest->itext_keys = 0;
  dest->itext_langtags = 0;
  dest->itext_transkeys = 0;
  dest->itext_strings = 0;
  dest->itext_num = 0;
  for(i = 0; i != source->itext_num; ++i)
  {
    CERROR_TRY_RETURN(lodepng_add_itext(dest, source->itext_keys[i], source->itext_langtags[i],
                                        source->itext_transkeys[i], source->itext_strings[i]));
  }
  return 0;
}

void lodepng_clear_itext(LodePNGInfo* info)
{
  LodePNGIText_cleanup(info);
}

unsigned lodepng_add_itext(LodePNGInfo* info, const char* key, const char* langtag,
                           const char* transkey, const char* str)
{
  char** new_keys = (char**)(lodepng_realloc(info->itext_keys, sizeof(char*) * (info->itext_num + 1)));
  char** new_langtags = (char**)(lodepng_realloc(info->itext_langtags, sizeof(char*) * (info->itext_num + 1)));
  char** new_transkeys = (char**)(lodepng_realloc(info->itext_transkeys, sizeof(char*) * (info->itext_num + 1)));
  char** new_strings = (char**)(lodepng_realloc(info->itext_strings, sizeof(char*) * (info->itext_num + 1)));
  if(!new_keys || !new_langtags || !new_transkeys || !new_strings)
  {
    lodepng_free(new_keys);
    lodepng_free(new_langtags);
    lodepng_free(new_transkeys);
    lodepng_free(new_strings);
    return 83; /*alloc fail*/
  }

  ++info->itext_num;
  info->itext_keys = new_keys;
  info->itext_langtags = new_langtags;
  info->itext_transkeys = new_transkeys;
  info->itext_strings = new_strings;

  string_init(&info->itext_keys[info->itext_num - 1]);
  string_set(&info->itext_keys[info->itext_num - 1], key);

  string_init(&info->itext_langtags[info->itext_num - 1]);
  string_set(&info->itext_langtags[info->itext_num - 1], langtag);

  string_init(&info->itext_transkeys[info->itext_num - 1]);
  string_set(&info->itext_transkeys[info->itext_num - 1], transkey);

  string_init(&info->itext_strings[info->itext_num - 1]);
  string_set(&info->itext_strings[info->itext_num - 1], str);

  return 0;
}
#endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/

void lodepng_info_init(LodePNGInfo* info)
{
  lodepng_color_mode_init(&info->color);
  info->interlace_method = 0;
  info->compression_method = 0;
  info->filter_method = 0;
#ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
  info->background_defined = 0;
  info->background_r = info->background_g = info->background_b = 0;

  LodePNGText_init(info);
  LodePNGIText_init(info);

  info->time_defined = 0;
  info->phys_defined = 0;

  LodePNGUnknownChunks_init(info);
#endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/
}

void lodepng_info_cleanup(LodePNGInfo* info)
{
  lodepng_color_mode_cleanup(&info->color);
#ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
  LodePNGText_cleanup(info);
  LodePNGIText_cleanup(info);

  LodePNGUnknownChunks_cleanup(info);
#endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/
}

unsigned lodepng_info_copy(LodePNGInfo* dest, const LodePNGInfo* source)
{
  lodepng_info_cleanup(dest);
  *dest = *source;
  lodepng_color_mode_init(&dest->color);
  CERROR_TRY_RETURN(lodepng_color_mode_copy(&dest->color, &source->color));

#ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
  CERROR_TRY_RETURN(LodePNGText_copy(dest, source));
  CERROR_TRY_RETURN(LodePNGIText_copy(dest, source));

  LodePNGUnknownChunks_init(dest);
  CERROR_TRY_RETURN(LodePNGUnknownChunks_copy(dest, source));
#endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/
  return 0;
}

void lodepng_info_swap(LodePNGInfo* a, LodePNGInfo* b)
{
  LodePNGInfo temp = *a;
  *a = *b;
  *b = temp;
}

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

/*index: bitgroup index, bits: bitgroup size(1, 2 or 4), in: bitgroup value, out: octet array to add bits to*/
static void addColorBits(unsigned char* out, size_t index, unsigned bits, unsigned in)
{
  unsigned m = bits == 1 ? 7 : bits == 2 ? 3 : 1; /*8 / bits - 1*/
  /*p = the partial index in the byte, e.g. with 4 palettebits it is 0 for first half or 1 for second half*/
  unsigned p = index & m;
  in &= (1u << bits) - 1u; /*filter out any other bits of the input value*/
  in = in << (bits * (m - p));
  if(p == 0) out[index * bits / 8] = in;
  else out[index * bits / 8] |= in;
}

typedef struct ColorTree ColorTree;

/*
One node of a color tree
This is the data structure used to count the number of unique colors and to get a palette
index for a color. It's like an octree, but because the alpha channel is used too, each
node has 16 instead of 8 children.
*/
struct ColorTree
{
  ColorTree* children[16]; /*up to 16 pointers to ColorTree of next level*/
  int index; /*the payload. Only has a meaningful value if this is in the last level*/
};

static void color_tree_init(ColorTree* tree)
{
  int i;
  for(i = 0; i != 16; ++i) tree->children[i] = 0;
  tree->index = -1;
}

static void color_tree_cleanup(ColorTree* tree)
{
  int i;
  for(i = 0; i != 16; ++i)
  {
    if(tree->children[i])
    {
      color_tree_cleanup(tree->children[i]);
      lodepng_free(tree->children[i]);
    }
  }
}

/*returns -1 if color not present, its index otherwise*/
static int color_tree_get(ColorTree* tree, unsigned char r, unsigned char g, unsigned char b, unsigned char a)
{
  int bit = 0;
  for(bit = 0; bit < 8; ++bit)
  {
    int i = 8 * ((r >> bit) & 1) + 4 * ((g >> bit) & 1) + 2 * ((b >> bit) & 1) + 1 * ((a >> bit) & 1);
    if(!tree->children[i]) return -1;
    else tree = tree->children[i];
  }
  return tree ? tree->index : -1;
}

#ifdef LODEPNG_COMPILE_ENCODER
static int color_tree_has(ColorTree* tree, unsigned char r, unsigned char g, unsigned char b, unsigned char a)
{
  return color_tree_get(tree, r, g, b, a) >= 0;
}
#endif /*LODEPNG_COMPILE_ENCODER*/

/*color is not allowed to already exist.
Index should be >= 0 (it's signed to be compatible with using -1 for "doesn't exist")*/
static void color_tree_add(ColorTree* tree,
                           unsigned char r, unsigned char g, unsigned char b, unsigned char a, unsigned index)
{
  int bit;
  for(bit = 0; bit < 8; ++bit)
  {
    int i = 8 * ((r >> bit) & 1) + 4 * ((g >> bit) & 1) + 2 * ((b >> bit) & 1) + 1 * ((a >> bit) & 1);
    if(!tree->children[i])
    {
      tree->children[i] = (ColorTree*)lodepng_malloc(sizeof(ColorTree));
      color_tree_init(tree->children[i]);
    }
    tree = tree->children[i];
  }
  tree->index = (int)index;
}

/*put a pixel, given its RGBA color, into image of any color type*/
static unsigned rgba8ToPixel(unsigned char* out, size_t i,
                             const LodePNGColorMode* mode, ColorTree* tree /*for palette*/,
                             unsigned char r, unsigned char g, unsigned char b, unsigned char a)
{
  if(mode->colortype == LCT_GREY)
  {
    unsigned char grey = r; /*((unsigned short)r + g + b) / 3*/;
    if(mode->bitdepth == 8) out[i] = grey;
    else if(mode->bitdepth == 16) out[i * 2 + 0] = out[i * 2 + 1] = grey;
    else
    {
      /*take the most significant bits of grey*/
      grey = (grey >> (8 - mode->bitdepth)) & ((1 << mode->bitdepth) - 1);
      addColorBits(out, i, mode->bitdepth, grey);
    }
  }
  else if(mode->colortype == LCT_RGB)
  {
    if(mode->bitdepth == 8)
    {
      out[i * 3 + 0] = r;
      out[i * 3 + 1] = g;
      out[i * 3 + 2] = b;
    }
    else
    {
      out[i * 6 + 0] = out[i * 6 + 1] = r;
      out[i * 6 + 2] = out[i * 6 + 3] = g;
      out[i * 6 + 4] = out[i * 6 + 5] = b;
    }
  }
  else if(mode->colortype == LCT_PALETTE)
  {
    int index = color_tree_get(tree, r, g, b, a);
    if(index < 0) return 82; /*color not in palette*/
    if(mode->bitdepth == 8) out[i] = index;
    else addColorBits(out, i, mode->bitdepth, (unsigned)index);
  }
  else if(mode->colortype == LCT_GREY_ALPHA)
  {
    unsigned char grey = r; /*((unsigned short)r + g + b) / 3*/;
    if(mode->bitdepth == 8)
    {
      out[i * 2 + 0] = grey;
      out[i * 2 + 1] = a;
    }
    else if(mode->bitdepth == 16)
    {
      out[i * 4 + 0] = out[i * 4 + 1] = grey;
      out[i * 4 + 2] = out[i * 4 + 3] = a;
    }
  }
  else if(mode->colortype == LCT_RGBA)
  {
    if(mode->bitdepth == 8)
    {
      out[i * 4 + 0] = r;
      out[i * 4 + 1] = g;
      out[i * 4 + 2] = b;
      out[i * 4 + 3] = a;
    }
    else
    {
      out[i * 8 + 0] = out[i * 8 + 1] = r;
      out[i * 8 + 2] = out[i * 8 + 3] = g;
      out[i * 8 + 4] = out[i * 8 + 5] = b;
      out[i * 8 + 6] = out[i * 8 + 7] = a;
    }
  }

  return 0; /*no error*/
}

/*put a pixel, given its RGBA16 color, into image of any color 16-bitdepth type*/
static void rgba16ToPixel(unsigned char* out, size_t i,
                         const LodePNGColorMode* mode,
                         unsigned short r, unsigned short g, unsigned short b, unsigned short a)
{
  if(mode->colortype == LCT_GREY)
  {
    unsigned short grey = r; /*((unsigned)r + g + b) / 3*/;
    out[i * 2 + 0] = (grey >> 8) & 255;
    out[i * 2 + 1] = grey & 255;
  }
  else if(mode->colortype == LCT_RGB)
  {
    out[i * 6 + 0] = (r >> 8) & 255;
    out[i * 6 + 1] = r & 255;
    out[i * 6 + 2] = (g >> 8) & 255;
    out[i * 6 + 3] = g & 255;
    out[i * 6 + 4] = (b >> 8) & 255;
    out[i * 6 + 5] = b & 255;
  }
  else if(mode->colortype == LCT_GREY_ALPHA)
  {
    unsigned short grey = r; /*((unsigned)r + g + b) / 3*/;
    out[i * 4 + 0] = (grey >> 8) & 255;
    out[i * 4 + 1] = grey & 255;
    out[i * 4 + 2] = (a >> 8) & 255;
    out[i * 4 + 3] = a & 255;
  }
  else if(mode->colortype == LCT_RGBA)
  {
    out[i * 8 + 0] = (r >> 8) & 255;
    out[i * 8 + 1] = r & 255;
    out[i * 8 + 2] = (g >> 8) & 255;
    out[i * 8 + 3] = g & 255;
    out[i * 8 + 4] = (b >> 8) & 255;
    out[i * 8 + 5] = b & 255;
    out[i * 8 + 6] = (a >> 8) & 255;
    out[i * 8 + 7] = a & 255;
  }
}

/*Get RGBA8 color of pixel with index i (y * width + x) from the raw image with given color type.*/
static void getPixelColorRGBA8(unsigned char* r, unsigned char* g,
                               unsigned char* b, unsigned char* a,
                               const unsigned char* in, size_t i,
                               const LodePNGColorMode* mode)
{
  if(mode->colortype == LCT_GREY)
  {
    if(mode->bitdepth == 8)
    {
      *r = *g = *b = in[i];
      if(mode->key_defined && *r == mode->key_r) *a = 0;
      else *a = 255;
    }
    else if(mode->bitdepth == 16)
    {
      *r = *g = *b = in[i * 2 + 0];
      if(mode->key_defined && 256U * in[i * 2 + 0] + in[i * 2 + 1] == mode->key_r) *a = 0;
      else *a = 255;
    }
    else
    {
      unsigned highest = ((1U << mode->bitdepth) - 1U); /*highest possible value for this bit depth*/
      size_t j = i * mode->bitdepth;
      unsigned value = readBitsFromReversedStream(&j, in, mode->bitdepth);
      *r = *g = *b = (value * 255) / highest;
      if(mode->key_defined && value == mode->key_r) *a = 0;
      else *a = 255;
    }
  }
  else if(mode->colortype == LCT_RGB)
  {
    if(mode->bitdepth == 8)
    {
      *r = in[i * 3 + 0]; *g = in[i * 3 + 1]; *b = in[i * 3 + 2];
      if(mode->key_defined && *r == mode->key_r && *g == mode->key_g && *b == mode->key_b) *a = 0;
      else *a = 255;
    }
    else
    {
      *r = in[i * 6 + 0];
      *g = in[i * 6 + 2];
      *b = in[i * 6 + 4];
      if(mode->key_defined && 256U * in[i * 6 + 0] + in[i * 6 + 1] == mode->key_r
         && 256U * in[i * 6 + 2] + in[i * 6 + 3] == mode->key_g
         && 256U * in[i * 6 + 4] + in[i * 6 + 5] == mode->key_b) *a = 0;
      else *a = 255;
    }
  }
  else if(mode->colortype == LCT_PALETTE)
  {
    unsigned index;
    if(mode->bitdepth == 8) index = in[i];
    else
    {
      size_t j = i * mode->bitdepth;
      index = readBitsFromReversedStream(&j, in, mode->bitdepth);
    }

    if(index >= mode->palettesize)
    {
      /*This is an error according to the PNG spec, but common PNG decoders make it black instead.
      Done here too, slightly faster due to no error handling needed.*/
      *r = *g = *b = 0;
      *a = 255;
    }
    else
    {
      *r = mode->palette[index * 4 + 0];
      *g = mode->palette[index * 4 + 1];
      *b = mode->palette[index * 4 + 2];
      *a = mode->palette[index * 4 + 3];
    }
  }
  else if(mode->colortype == LCT_GREY_ALPHA)
  {
    if(mode->bitdepth == 8)
    {
      *r = *g = *b = in[i * 2 + 0];
      *a = in[i * 2 + 1];
    }
    else
    {
      *r = *g = *b = in[i * 4 + 0];
      *a = in[i * 4 + 2];
    }
  }
  else if(mode->colortype == LCT_RGBA)
  {
    if(mode->bitdepth == 8)
    {
      *r = in[i * 4 + 0];
      *g = in[i * 4 + 1];
      *b = in[i * 4 + 2];
      *a = in[i * 4 + 3];
    }
    else
    {
      *r = in[i * 8 + 0];
      *g = in[i * 8 + 2];
      *b = in[i * 8 + 4];
      *a = in[i * 8 + 6];
    }
  }
}

/*Similar to getPixelColorRGBA8, but with all the for loops inside of the color
mode test cases, optimized to convert the colors much faster, when converting
to RGBA or RGB with 8 bit per cannel. buffer must be RGBA or RGB output with
enough memory, if has_alpha is true the output is RGBA. mode has the color mode
of the input buffer.*/
static void getPixelColorsRGBA8(unsigned char* buffer, size_t numpixels,
                                unsigned has_alpha, const unsigned char* in,
                                const LodePNGColorMode* mode)
{
  unsigned num_channels = has_alpha ? 4 : 3;
  size_t i;
  if(mode->colortype == LCT_GREY)
  {
    if(mode->bitdepth == 8)
    {
      for(i = 0; i != numpixels; ++i, buffer += num_channels)
      {
        buffer[0] = buffer[1] = buffer[2] = in[i];
        if(has_alpha) buffer[3] = mode->key_defined && in[i] == mode->key_r ? 0 : 255;
      }
    }
    else if(mode->bitdepth == 16)
    {
      for(i = 0; i != numpixels; ++i, buffer += num_channels)
      {
        buffer[0] = buffer[1] = buffer[2] = in[i * 2];
        if(has_alpha) buffer[3] = mode->key_defined && 256U * in[i * 2 + 0] + in[i * 2 + 1] == mode->key_r ? 0 : 255;
      }
    }
    else
    {
      unsigned highest = ((1U << mode->bitdepth) - 1U); /*highest possible value for this bit depth*/
      size_t j = 0;
      for(i = 0; i != numpixels; ++i, buffer += num_channels)
      {
        unsigned value = readBitsFromReversedStream(&j, in, mode->bitdepth);
        buffer[0] = buffer[1] = buffer[2] = (value * 255) / highest;
        if(has_alpha) buffer[3] = mode->key_defined && value == mode->key_r ? 0 : 255;
      }
    }
  }
  else if(mode->colortype == LCT_RGB)
  {
    if(mode->bitdepth == 8)
    {
      for(i = 0; i != numpixels; ++i, buffer += num_channels)
      {
        buffer[0] = in[i * 3 + 0];
        buffer[1] = in[i * 3 + 1];
        buffer[2] = in[i * 3 + 2];
        if(has_alpha) buffer[3] = mode->key_defined && buffer[0] == mode->key_r
           && buffer[1]== mode->key_g && buffer[2] == mode->key_b ? 0 : 255;
      }
    }
    else
    {
      for(i = 0; i != numpixels; ++i, buffer += num_channels)
      {
        buffer[0] = in[i * 6 + 0];
        buffer[1] = in[i * 6 + 2];
        buffer[2] = in[i * 6 + 4];
        if(has_alpha) buffer[3] = mode->key_defined
           && 256U * in[i * 6 + 0] + in[i * 6 + 1] == mode->key_r
           && 256U * in[i * 6 + 2] + in[i * 6 + 3] == mode->key_g
           && 256U * in[i * 6 + 4] + in[i * 6 + 5] == mode->key_b ? 0 : 255;
      }
    }
  }
  else if(mode->colortype == LCT_PALETTE)
  {
    unsigned index;
    size_t j = 0;
    for(i = 0; i != numpixels; ++i, buffer += num_channels)
    {
      if(mode->bitdepth == 8) index = in[i];
      else index = readBitsFromReversedStream(&j, in, mode->bitdepth);

      if(index >= mode->palettesize)
      {
        /*This is an error according to the PNG spec, but most PNG decoders make it black instead.
        Done here too, slightly faster due to no error handling needed.*/
        buffer[0] = buffer[1] = buffer[2] = 0;
        if(has_alpha) buffer[3] = 255;
      }
      else
      {
        buffer[0] = mode->palette[index * 4 + 0];
        buffer[1] = mode->palette[index * 4 + 1];
        buffer[2] = mode->palette[index * 4 + 2];
        if(has_alpha) buffer[3] = mode->palette[index * 4 + 3];
      }
    }
  }
  else if(mode->colortype == LCT_GREY_ALPHA)
  {
    if(mode->bitdepth == 8)
    {
      for(i = 0; i != numpixels; ++i, buffer += num_channels)
      {
        buffer[0] = buffer[1] = buffer[2] = in[i * 2 + 0];
        if(has_alpha) buffer[3] = in[i * 2 + 1];
      }
    }
    else
    {
      for(i = 0; i != numpixels; ++i, buffer += num_channels)
      {
        buffer[0] = buffer[1] = buffer[2] = in[i * 4 + 0];
        if(has_alpha) buffer[3] = in[i * 4 + 2];
      }
    }
  }
  else if(mode->colortype == LCT_RGBA)
  {
    if(mode->bitdepth == 8)
    {
      for(i = 0; i != numpixels; ++i, buffer += num_channels)
      {
        buffer[0] = in[i * 4 + 0];
        buffer[1] = in[i * 4 + 1];
        buffer[2] = in[i * 4 + 2];
        if(has_alpha) buffer[3] = in[i * 4 + 3];
      }
    }
    else
    {
      for(i = 0; i != numpixels; ++i, buffer += num_channels)
      {
        buffer[0] = in[i * 8 + 0];
        buffer[1] = in[i * 8 + 2];
        buffer[2] = in[i * 8 + 4];
        if(has_alpha) buffer[3] = in[i * 8 + 6];
      }
    }
  }
}

/*Get RGBA16 color of pixel with index i (y * width + x) from the raw image with
given color type, but the given color type must be 16-bit itself.*/
static void getPixelColorRGBA16(unsigned short* r, unsigned short* g, unsigned short* b, unsigned short* a,
                                const unsigned char* in, size_t i, const LodePNGColorMode* mode)
{
  if(mode->colortype == LCT_GREY)
  {
    *r = *g = *b = 256 * in[i * 2 + 0] + in[i * 2 + 1];
    if(mode->key_defined && 256U * in[i * 2 + 0] + in[i * 2 + 1] == mode->key_r) *a = 0;
    else *a = 65535;
  }
  else if(mode->colortype == LCT_RGB)
  {
    *r = 256u * in[i * 6 + 0] + in[i * 6 + 1];
    *g = 256u * in[i * 6 + 2] + in[i * 6 + 3];
    *b = 256u * in[i * 6 + 4] + in[i * 6 + 5];
    if(mode->key_defined
       && 256u * in[i * 6 + 0] + in[i * 6 + 1] == mode->key_r
       && 256u * in[i * 6 + 2] + in[i * 6 + 3] == mode->key_g
       && 256u * in[i * 6 + 4] + in[i * 6 + 5] == mode->key_b) *a = 0;
    else *a = 65535;
  }
  else if(mode->colortype == LCT_GREY_ALPHA)
  {
    *r = *g = *b = 256u * in[i * 4 + 0] + in[i * 4 + 1];
    *a = 256u * in[i * 4 + 2] + in[i * 4 + 3];
  }
  else if(mode->colortype == LCT_RGBA)
  {
    *r = 256u * in[i * 8 + 0] + in[i * 8 + 1];
    *g = 256u * in[i * 8 + 2] + in[i * 8 + 3];
    *b = 256u * in[i * 8 + 4] + in[i * 8 + 5];
    *a = 256u * in[i * 8 + 6] + in[i * 8 + 7];
  }
}

unsigned lodepng_convert(unsigned char* out, const unsigned char* in,
                         const LodePNGColorMode* mode_out, const LodePNGColorMode* mode_in,
                         unsigned w, unsigned h)
{
  size_t i;
  ColorTree tree;
  size_t numpixels = (size_t)w * (size_t)h;
  unsigned error = 0;

  if(lodepng_color_mode_equal(mode_out, mode_in))
  {
    size_t numbytes = lodepng_get_raw_size(w, h, mode_in);
    for(i = 0; i != numbytes; ++i) out[i] = in[i];
    return 0;
  }

  if(mode_out->colortype == LCT_PALETTE)
  {
    size_t palettesize = mode_out->palettesize;
    const unsigned char* palette = mode_out->palette;
    size_t palsize = (size_t)1u << mode_out->bitdepth;
    /*if the user specified output palette but did not give the values, assume
    they want the values of the input color type (assuming that one is palette).
    Note that we never create a new palette ourselves.*/
    if(palettesize == 0)
    {
      palettesize = mode_in->palettesize;
      palette = mode_in->palette;
      /*if the input was also palette with same bitdepth, then the color types are also
      equal, so copy literally. This to preserve the exact indices that were in the PNG
      even in case there are duplicate colors in the palette.*/
      if (mode_in->colortype == LCT_PALETTE && mode_in->bitdepth == mode_out->bitdepth)
      {
        size_t numbytes = lodepng_get_raw_size(w, h, mode_in);
        for(i = 0; i != numbytes; ++i) out[i] = in[i];
        return 0;
      }
    }
    if(palettesize < palsize) palsize = palettesize;
    color_tree_init(&tree);
    for(i = 0; i != palsize; ++i)
    {
      const unsigned char* p = &palette[i * 4];
      color_tree_add(&tree, p[0], p[1], p[2], p[3], (unsigned)i);
    }
  }

  if(mode_in->bitdepth == 16 && mode_out->bitdepth == 16)
  {
    for(i = 0; i != numpixels; ++i)
    {
      unsigned short r = 0, g = 0, b = 0, a = 0;
      getPixelColorRGBA16(&r, &g, &b, &a, in, i, mode_in);
      rgba16ToPixel(out, i, mode_out, r, g, b, a);
    }
  }
  else if(mode_out->bitdepth == 8 && mode_out->colortype == LCT_RGBA)
  {
    getPixelColorsRGBA8(out, numpixels, 1, in, mode_in);
  }
  else if(mode_out->bitdepth == 8 && mode_out->colortype == LCT_RGB)
  {
    getPixelColorsRGBA8(out, numpixels, 0, in, mode_in);
  }
  else
  {
    unsigned char r = 0, g = 0, b = 0, a = 0;
    for(i = 0; i != numpixels; ++i)
    {
      getPixelColorRGBA8(&r, &g, &b, &a, in, i, mode_in);
      error = rgba8ToPixel(out, i, mode_out, &tree, r, g, b, a);
      if (error) break;
    }
  }

  if(mode_out->colortype == LCT_PALETTE)
  {
    color_tree_cleanup(&tree);
  }

  return error;
}

#ifdef LODEPNG_COMPILE_ENCODER

void lodepng_color_profile_init(LodePNGColorProfile* profile)
{
  profile->colored = 0;
  profile->key = 0;
  profile->key_r = profile->key_g = profile->key_b = 0;
  profile->alpha = 0;
  profile->numcolors = 0;
  profile->bits = 1;
}

/*function used for debug purposes with C++*/
/*void printColorProfile(LodePNGColorProfile* p)
{
  std::cout << "colored: " << (int)p->colored << ", ";
  std::cout << "key: " << (int)p->key << ", ";
  std::cout << "key_r: " << (int)p->key_r << ", ";
  std::cout << "key_g: " << (int)p->key_g << ", ";
  std::cout << "key_b: " << (int)p->key_b << ", ";
  std::cout << "alpha: " << (int)p->alpha << ", ";
  std::cout << "numcolors: " << (int)p->numcolors << ", ";
  std::cout << "bits: " << (int)p->bits << std::endl;
}*/

/*Returns how many bits needed to represent given value (max 8 bit)*/
static unsigned getValueRequiredBits(unsigned char value)
{
  if(value == 0 || value == 255) return 1;
  /*The scaling of 2-bit and 4-bit values uses multiples of 85 and 17*/
  if(value % 17 == 0) return value % 85 == 0 ? 2 : 4;
  return 8;
}

/*profile must already have been inited with mode.
It's ok to set some parameters of profile to done already.*/
unsigned lodepng_get_color_profile(LodePNGColorProfile* profile,
                                   const unsigned char* in, unsigned w, unsigned h,
                                   const LodePNGColorMode* mode)
{
  unsigned error = 0;
  size_t i;
  ColorTree tree;
  size_t numpixels = (size_t)w * (size_t)h;

  unsigned colored_done = lodepng_is_greyscale_type(mode) ? 1 : 0;
  unsigned alpha_done = lodepng_can_have_alpha(mode) ? 0 : 1;
  unsigned numcolors_done = 0;
  unsigned bpp = lodepng_get_bpp(mode);
  unsigned bits_done = bpp == 1 ? 1 : 0;
  unsigned maxnumcolors = 257;
  unsigned sixteen = 0;
  if(bpp <= 8) maxnumcolors = bpp == 1 ? 2 : (bpp == 2 ? 4 : (bpp == 4 ? 16 : 256));

  color_tree_init(&tree);

  /*Check if the 16-bit input is truly 16-bit*/
  if(mode->bitdepth == 16)
  {
    unsigned short r, g, b, a;
    for(i = 0; i != numpixels; ++i)
    {
      getPixelColorRGBA16(&r, &g, &b, &a, in, i, mode);
      if((r & 255) != ((r >> 8) & 255) || (g & 255) != ((g >> 8) & 255) ||
         (b & 255) != ((b >> 8) & 255) || (a & 255) != ((a >> 8) & 255)) /*first and second byte differ*/
      {
        sixteen = 1;
        break;
      }
    }
  }

  if(sixteen)
  {
    unsigned short r = 0, g = 0, b = 0, a = 0;
    profile->bits = 16;
    bits_done = numcolors_done = 1; /*counting colors no longer useful, palette doesn't support 16-bit*/

    for(i = 0; i != numpixels; ++i)
    {
      getPixelColorRGBA16(&r, &g, &b, &a, in, i, mode);

      if(!colored_done && (r != g || r != b))
      {
        profile->colored = 1;
        colored_done = 1;
      }

      if(!alpha_done)
      {
        unsigned matchkey = (r == profile->key_r && g == profile->key_g && b == profile->key_b);
        if(a != 65535 && (a != 0 || (profile->key && !matchkey)))
        {
          profile->alpha = 1;
          profile->key = 0;
          alpha_done = 1;
        }
        else if(a == 0 && !profile->alpha && !profile->key)
        {
          profile->key = 1;
          profile->key_r = r;
          profile->key_g = g;
          profile->key_b = b;
        }
        else if(a == 65535 && profile->key && matchkey)
        {
          /* Color key cannot be used if an opaque pixel also has that RGB color. */
          profile->alpha = 1;
          profile->key = 0;
          alpha_done = 1;
        }
      }
      if(alpha_done && numcolors_done && colored_done && bits_done) break;
    }

    if(profile->key && !profile->alpha)
    {
      for(i = 0; i != numpixels; ++i)
      {
        getPixelColorRGBA16(&r, &g, &b, &a, in, i, mode);
        if(a != 0 && r == profile->key_r && g == profile->key_g && b == profile->key_b)
        {
          /* Color key cannot be used if an opaque pixel also has that RGB color. */
          profile->alpha = 1;
          profile->key = 0;
          alpha_done = 1;
        }
      }
    }
  }
  else /* < 16-bit */
  {
    unsigned char r = 0, g = 0, b = 0, a = 0;
    for(i = 0; i != numpixels; ++i)
    {
      getPixelColorRGBA8(&r, &g, &b, &a, in, i, mode);

      if(!bits_done && profile->bits < 8)
      {
        /*only r is checked, < 8 bits is only relevant for greyscale*/
        unsigned bits = getValueRequiredBits(r);
        if(bits > profile->bits) profile->bits = bits;
      }
      bits_done = (profile->bits >= bpp);

      if(!colored_done && (r != g || r != b))
      {
        profile->colored = 1;
        colored_done = 1;
        if(profile->bits < 8) profile->bits = 8; /*PNG has no colored modes with less than 8-bit per channel*/
      }

      if(!alpha_done)
      {
        unsigned matchkey = (r == profile->key_r && g == profile->key_g && b == profile->key_b);
        if(a != 255 && (a != 0 || (profile->key && !matchkey)))
        {
          profile->alpha = 1;
          profile->key = 0;
          alpha_done = 1;
          if(profile->bits < 8) profile->bits = 8; /*PNG has no alphachannel modes with less than 8-bit per channel*/
        }
        else if(a == 0 && !profile->alpha && !profile->key)
        {
          profile->key = 1;
          profile->key_r = r;
          profile->key_g = g;
          profile->key_b = b;
        }
        else if(a == 255 && profile->key && matchkey)
        {
          /* Color key cannot be used if an opaque pixel also has that RGB color. */
          profile->alpha = 1;
          profile->key = 0;
          alpha_done = 1;
          if(profile->bits < 8) profile->bits = 8; /*PNG has no alphachannel modes with less than 8-bit per channel*/
        }
      }

      if(!numcolors_done)
      {
        if(!color_tree_has(&tree, r, g, b, a))
        {
          color_tree_add(&tree, r, g, b, a, profile->numcolors);
          if(profile->numcolors < 256)
          {
            unsigned char* p = profile->palette;
            unsigned n = profile->numcolors;
            p[n * 4 + 0] = r;
            p[n * 4 + 1] = g;
            p[n * 4 + 2] = b;
            p[n * 4 + 3] = a;
          }
          ++profile->numcolors;
          numcolors_done = profile->numcolors >= maxnumcolors;
        }
      }

      if(alpha_done && numcolors_done && colored_done && bits_done) break;
    }

    if(profile->key && !profile->alpha)
    {
      for(i = 0; i != numpixels; ++i)
      {
        getPixelColorRGBA8(&r, &g, &b, &a, in, i, mode);
        if(a != 0 && r == profile->key_r && g == profile->key_g && b == profile->key_b)
        {
          /* Color key cannot be used if an opaque pixel also has that RGB color. */
          profile->alpha = 1;
          profile->key = 0;
          alpha_done = 1;
          if(profile->bits < 8) profile->bits = 8; /*PNG has no alphachannel modes with less than 8-bit per channel*/
        }
      }
    }

    /*make the profile's key always 16-bit for consistency - repeat each byte twice*/
    profile->key_r += (profile->key_r << 8);
    profile->key_g += (profile->key_g << 8);
    profile->key_b += (profile->key_b << 8);
  }

  color_tree_cleanup(&tree);
  return error;
}

/*Automatically chooses color type that gives smallest amount of bits in the
output image, e.g. grey if there are only greyscale pixels, palette if there
are less than 256 colors, ...
Updates values of mode with a potentially smaller color model. mode_out should
contain the user chosen color model, but will be overwritten with the new chosen one.*/
unsigned lodepng_auto_choose_color(LodePNGColorMode* mode_out,
                                   const unsigned char* image, unsigned w, unsigned h,
                                   const LodePNGColorMode* mode_in)
{
  LodePNGColorProfile prof;
  unsigned error = 0;
  unsigned palettebits, palette_ok;
  size_t i, n;
  size_t numpixels = (size_t)w * (size_t)h;

  lodepng_color_profile_init(&prof);
  error = lodepng_get_color_profile(&prof, image, w, h, mode_in);
  if(error) return error;
  mode_out->key_defined = 0;

  if(prof.key && numpixels <= 16)
  {
    prof.alpha = 1; /*too few pixels to justify tRNS chunk overhead*/
    prof.key = 0;
    if(prof.bits < 8) prof.bits = 8; /*PNG has no alphachannel modes with less than 8-bit per channel*/
  }
  n = prof.numcolors;
  palettebits = n <= 2 ? 1 : (n <= 4 ? 2 : (n <= 16 ? 4 : 8));
  palette_ok = n <= 256 && prof.bits <= 8;
  if(numpixels < n * 2) palette_ok = 0; /*don't add palette overhead if image has only a few pixels*/
  if(!prof.colored && prof.bits <= palettebits) palette_ok = 0; /*grey is less overhead*/

  if(palette_ok)
  {
    unsigned char* p = prof.palette;
    lodepng_palette_clear(mode_out); /*remove potential earlier palette*/
    for(i = 0; i != prof.numcolors; ++i)
    {
      error = lodepng_palette_add(mode_out, p[i * 4 + 0], p[i * 4 + 1], p[i * 4 + 2], p[i * 4 + 3]);
      if(error) break;
    }

    mode_out->colortype = LCT_PALETTE;
    mode_out->bitdepth = palettebits;

    if(mode_in->colortype == LCT_PALETTE && mode_in->palettesize >= mode_out->palettesize
        && mode_in->bitdepth == mode_out->bitdepth)
    {
      /*If input should have same palette colors, keep original to preserve its order and prevent conversion*/
      lodepng_color_mode_cleanup(mode_out);
      lodepng_color_mode_copy(mode_out, mode_in);
    }
  }
  else /*8-bit or 16-bit per channel*/
  {
    mode_out->bitdepth = prof.bits;
    mode_out->colortype = prof.alpha ? (prof.colored ? LCT_RGBA : LCT_GREY_ALPHA)
                                     : (prof.colored ? LCT_RGB : LCT_GREY);

    if(prof.key)
    {
      unsigned mask = (1u << mode_out->bitdepth) - 1u; /*profile always uses 16-bit, mask converts it*/
      mode_out->key_r = prof.key_r & mask;
      mode_out->key_g = prof.key_g & mask;
      mode_out->key_b = prof.key_b & mask;
      mode_out->key_defined = 1;
    }
  }

  return error;
}

#endif /* #ifdef LODEPNG_COMPILE_ENCODER */

/*
Paeth predicter, used by PNG filter type 4
The parameters are of type short, but should come from unsigned chars, the shorts
are only needed to make the paeth calculation correct.
*/
static unsigned char paethPredictor(short a, short b, short c)
{
  short pa = abs(b - c);
  short pb = abs(a - c);
  short pc = abs(a + b - c - c);

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

/*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*/

/*
Outputs various dimensions and positions in the image related to the Adam7 reduced images.
passw: output containing the width of the 7 passes
passh: output containing the height of the 7 passes
filter_passstart: output containing the index of the start and end of each
 reduced image with filter bytes
padded_passstart output containing the index of the start and end of each
 reduced image when without filter bytes but with padded scanlines
passstart: output containing the index of the start and end of each reduced
 image without padding between scanlines, but still padding between the images
w, h: width and height of non-interlaced image
bpp: bits per pixel
"padded" is only relevant if bpp is less than 8 and a scanline or image does not
 end at a full byte
*/
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 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)
  {
    /*if passw[i] is 0, it's 0 bytes, not 1 (no filtertype-byte)*/
    filter_passstart[i + 1] = filter_passstart[i]
                            + ((passw[i] && passh[i]) ? passh[i] * (1 + (passw[i] * bpp + 7) / 8) : 0);
    /*bits padded if needed to fill full byte at end of each scanline*/
    padded_passstart[i + 1] = padded_passstart[i] + passh[i] * ((passw[i] * bpp + 7) / 8);
    /*only padded at end of reduced image*/
    passstart[i + 1] = passstart[i] + (passh[i] * passw[i] * bpp + 7) / 8;
  }
}

#ifdef LODEPNG_COMPILE_DECODER

/* ////////////////////////////////////////////////////////////////////////// */
/* / PNG Decoder                                                            / */
/* ////////////////////////////////////////////////////////////////////////// */

/*read the information from the header and store it in the LodePNGInfo. return value is error*/
unsigned lodepng_inspect(unsigned* w, unsigned* h, LodePNGState* state,
                         const unsigned char* in, size_t insize)
{
  LodePNGInfo* info = &state->info_png;
  if(insize == 0 || in == 0)
  {
    CERROR_RETURN_ERROR(state->error, 48); /*error: the given data is empty*/
  }
  if(insize < 33)
  {
    CERROR_RETURN_ERROR(state->error, 27); /*error: the data length is smaller than the length of a PNG header*/
  }

  /*when decoding a new PNG image, make sure all parameters created after previous decoding are reset*/
  lodepng_info_cleanup(info);
  lodepng_info_init(info);

  if(in[0] != 137 || in[1] != 80 || in[2] != 78 || in[3] != 71
     || in[4] != 13 || in[5] != 10 || in[6] != 26 || in[7] != 10)
  {
    CERROR_RETURN_ERROR(state->error, 28); /*error: the first 8 bytes are not the correct PNG signature*/
  }
  if(lodepng_chunk_length(in + 8) != 13)
  {
    CERROR_RETURN_ERROR(state->error, 94); /*error: header size must be 13 bytes*/
  }
  if(!lodepng_chunk_type_equals(in + 8, "IHDR"))
  {
    CERROR_RETURN_ERROR(state->error, 29); /*error: it doesn't start with a IHDR chunk!*/
  }

  /*read the values given in the header*/
  *w = lodepng_read32bitInt(&in[16]);
  *h = lodepng_read32bitInt(&in[20]);
  info->color.bitdepth = in[24];
  info->color.colortype = (LodePNGColorType)in[25];
  info->compression_method = in[26];
  info->filter_method = in[27];
  info->interlace_method = in[28];

  if(*w == 0 || *h == 0)
  {
    CERROR_RETURN_ERROR(state->error, 93);
  }

  if(!state->decoder.ignore_crc)
  {
    unsigned CRC = lodepng_read32bitInt(&in[29]);
    unsigned checksum = lodepng_crc32(&in[12], 17);
    if(CRC != checksum)
    {
      CERROR_RETURN_ERROR(state->error, 57); /*invalid CRC*/
    }
  }

  /*error: only compression method 0 is allowed in the specification*/
  if(info->compression_method != 0) CERROR_RETURN_ERROR(state->error, 32);
  /*error: only filter method 0 is allowed in the specification*/
  if(info->filter_method != 0) CERROR_RETURN_ERROR(state->error, 33);
  /*error: only interlace methods 0 and 1 exist in the specification*/
  if(info->interlace_method > 1) CERROR_RETURN_ERROR(state->error, 34);

  state->error = checkColorValidity(info->color.colortype, info->color.bitdepth);
  return state->error;
}

static unsigned unfilterScanline(unsigned char* recon, const unsigned char* scanline, const unsigned char* precon,
                                 size_t bytewidth, unsigned char filterType, size_t length)
{
  /*
  For PNG filter method 0
  unfilter a PNG image scanline by scanline. when the pixels are smaller than 1 byte,
  the filter works byte per byte (bytewidth = 1)
  precon is the previous unfiltered scanline, recon the result, scanline the current one
  the incoming scanlines do NOT include the filtertype byte, that one is given in the parameter filterType instead
  recon and scanline MAY be the same memory address! precon must be disjoint.
  */

  size_t i;
  switch(filterType)
  {
    case 0:
      for(i = 0; i != length; ++i) recon[i] = scanline[i];
      break;
    case 1:
      for(i = 0; i != bytewidth; ++i) recon[i] = scanline[i];
      for(i = bytewidth; i < length; ++i) recon[i] = scanline[i] + recon[i - bytewidth];
      break;
    case 2:
      if(precon)
      {
        for(i = 0; i != length; ++i) recon[i] = scanline[i] + precon[i];
      }
      else
      {
        for(i = 0; i != length; ++i) recon[i] = scanline[i];
      }
      break;
    case 3:
      if(precon)
      {
        for(i = 0; i != bytewidth; ++i) recon[i] = scanline[i] + (precon[i] >> 1);
        for(i = bytewidth; i < length; ++i) recon[i] = scanline[i] + ((recon[i - bytewidth] + precon[i]) >> 1);
      }
      else
      {
        for(i = 0; i != bytewidth; ++i) recon[i] = scanline[i];
        for(i = bytewidth; i < length; ++i) recon[i] = scanline[i] + (recon[i - bytewidth] >> 1);
      }
      break;
    case 4:
      if(precon)
      {
        for(i = 0; i != bytewidth; ++i)
        {
          recon[i] = (scanline[i] + precon[i]); /*paethPredictor(0, precon[i], 0) is always precon[i]*/
        }
        for(i = bytewidth; i < length; ++i)
        {
          recon[i] = (scanline[i] + paethPredictor(recon[i - bytewidth], precon[i], precon[i - bytewidth]));
        }
      }
      else
      {
        for(i = 0; i != bytewidth; ++i)
        {
          recon[i] = scanline[i];
        }
        for(i = bytewidth; i < length; ++i)
        {
          /*paethPredictor(recon[i - bytewidth], 0, 0) is always recon[i - bytewidth]*/
          recon[i] = (scanline[i] + recon[i - bytewidth]);
        }
      }
      break;
    default: return 36; /*error: unexisting filter type given*/
  }
  return 0;
}

static unsigned unfilter(unsigned char* out, const unsigned char* in, unsigned w, unsigned h, unsigned bpp)
{
  /*
  For PNG filter method 0
  this function unfilters a single image (e.g. without interlacing this is called once, with Adam7 seven times)
  out must have enough bytes allocated already, in must have the scanlines + 1 filtertype byte per scanline
  w and h are image dimensions or dimensions of reduced image, bpp is bits per pixel
  in and out are allowed to be the same memory address (but aren't the same size since in has the extra filter bytes)
  */

  unsigned y;
  unsigned char* prevline = 0;

  /*bytewidth is used for filtering, is 1 when bpp < 8, number of bytes per pixel otherwise*/
  size_t bytewidth = (bpp + 7) / 8;
  size_t linebytes = (w * bpp + 7) / 8;

  for(y = 0; y < h; ++y)
  {
    size_t outindex = linebytes * y;
    size_t inindex = (1 + linebytes) * y; /*the extra filterbyte added to each row*/
    unsigned char filterType = in[inindex];

    CERROR_TRY_RETURN(unfilterScanline(&out[outindex], &in[inindex + 1], prevline, bytewidth, filterType, linebytes));

    prevline = &out[outindex];
  }

  return 0;
}

/*
in: Adam7 interlaced image, with no padding bits between scanlines, but between
 reduced images so that each reduced image starts at a byte.
out: the same pixels, but re-ordered so that they're now a non-interlaced image with size w*h
bpp: bits per pixel
out has the following size in bits: w * h * bpp.
in is possibly bigger due to padding bits between reduced images.
out must be big enough AND must be 0 everywhere if bpp < 8 in the current implementation
(because that's likely a little bit faster)
NOTE: comments about padding bits are only relevant if bpp < 8
*/
static void Adam7_deinterlace(unsigned char* out, const unsigned char* in, unsigned w, unsigned h, unsigned bpp)
{
  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 = passstart[i] + (y * passw[i] + x) * bytewidth;
        size_t pixeloutstart = ((ADAM7_IY[i] + y * ADAM7_DY[i]) * w + ADAM7_IX[i] + x * ADAM7_DX[i]) * 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 = (8 * passstart[i]) + (y * ilinebits + x * bpp);
        obp = (ADAM7_IY[i] + y * ADAM7_DY[i]) * olinebits + (ADAM7_IX[i] + x * ADAM7_DX[i]) * bpp;
        for(b = 0; b < bpp; ++b)
        {
          unsigned char bit = readBitFromReversedStream(&ibp, in);
          /*note that this function assumes the out buffer is completely 0, use setBitOfReversedStream otherwise*/
          setBitOfReversedStream0(&obp, out, bit);
        }
      }
    }
  }
}

static void removePaddingBits(unsigned char* out, const unsigned char* in,
                              size_t olinebits, size_t ilinebits, unsigned h)
{
  /*
  After filtering there are still padding bits if scanlines have non multiple of 8 bit amounts. They need
  to be removed (except at last scanline of (Adam7-reduced) image) before working with pure image buffers
  for the Adam7 code, the color convert code and the output to the user.
  in and out are allowed to be the same buffer, in may also be higher but still overlapping; in must
  have >= ilinebits*h bits, out must have >= olinebits*h bits, olinebits must be <= ilinebits
  also used to move bits after earlier such operations happened, e.g. in a sequence of reduced images from Adam7
  only useful if (ilinebits - olinebits) is a value in the range 1..7
  */
  unsigned y;
  size_t diff = ilinebits - olinebits;
  size_t ibp = 0, obp = 0; /*input and output bit pointers*/
  for(y = 0; y < h; ++y)
  {
    size_t x;
    for(x = 0; x < olinebits; ++x)
    {
      unsigned char bit = readBitFromReversedStream(&ibp, in);
      setBitOfReversedStream(&obp, out, bit);
    }
    ibp += diff;
  }
}

/*out must be buffer big enough to contain full image, and in must contain the full decompressed data from
the IDAT chunks (with filter index bytes and possible padding bits)
return value is error*/
static unsigned postProcessScanlines(unsigned char* out, unsigned char* in,
                                     unsigned w, unsigned h, const LodePNGInfo* info_png)
{
  /*
  This function converts the filtered-padded-interlaced data into pure 2D image buffer with the PNG's colortype.
  Steps:
  *) if no Adam7: 1) unfilter 2) remove padding bits (= posible extra bits per scanline if bpp < 8)
  *) if adam7: 1) 7x unfilter 2) 7x remove padding bits 3) Adam7_deinterlace
  NOTE: the in buffer will be overwritten with intermediate data!
  */
  unsigned bpp = lodepng_get_bpp(&info_png->color);
  if(bpp == 0) return 31; /*error: invalid colortype*/

  if(info_png->interlace_method == 0)
  {
    if(bpp < 8 && w * bpp != ((w * bpp + 7) / 8) * 8)
    {
      CERROR_TRY_RETURN(unfilter(in, in, w, h, bpp));
      removePaddingBits(out, in, w * bpp, ((w * bpp + 7) / 8) * 8, h);
    }
    /*we can immediately filter into the out buffer, no other steps needed*/
    else CERROR_TRY_RETURN(unfilter(out, in, w, h, bpp));
  }
  else /*interlace_method is 1 (Adam7)*/
  {
    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);

    for(i = 0; i != 7; ++i)
    {
      CERROR_TRY_RETURN(unfilter(&in[padded_passstart[i]], &in[filter_passstart[i]], passw[i], passh[i], bpp));
      /*TODO: possible efficiency improvement: if in this reduced image the bits fit nicely in 1 scanline,
      move bytes instead of bits or move not at all*/
      if(bpp < 8)
      {
        /*remove padding bits in scanlines; after this there still may be padding
        bits between the different reduced images: each reduced image still starts nicely at a byte*/
        removePaddingBits(&in[passstart[i]], &in[padded_passstart[i]], passw[i] * bpp,
                          ((passw[i] * bpp + 7) / 8) * 8, passh[i]);
      }
    }

    Adam7_deinterlace(out, in, w, h, bpp);
  }

  return 0;
}

static unsigned readChunk_PLTE(LodePNGColorMode* color, const unsigned char* data, size_t chunkLength)
{
  unsigned pos = 0, i;
  if(color->palette) lodepng_free(color->palette);
  color->palettesize = chunkLength / 3;
  color->palette = (unsigned char*)lodepng_malloc(4 * color->palettesize);
  if(!color->palette && color->palettesize)
  {
    color->palettesize = 0;
    return 83; /*alloc fail*/
  }
  if(color->palettesize > 256) return 38; /*error: palette too big*/

  for(i = 0; i != color->palettesize; ++i)
  {
    color->palette[4 * i + 0] = data[pos++]; /*R*/
    color->palette[4 * i + 1] = data[pos++]; /*G*/
    color->palette[4 * i + 2] = data[pos++]; /*B*/
    color->palette[4 * i + 3] = 255; /*alpha*/
  }

  return 0; /* OK */
}

static unsigned readChunk_tRNS(LodePNGColorMode* color, const unsigned char* data, size_t chunkLength)
{
  unsigned i;
  if(color->colortype == LCT_PALETTE)
  {
    /*error: more alpha values given than there are palette entries*/
    if(chunkLength > color->palettesize) return 38;

    for(i = 0; i != chunkLength; ++i) color->palette[4 * i + 3] = data[i];
  }
  else if(color->colortype == LCT_GREY)
  {
    /*error: this chunk must be 2 bytes for greyscale image*/
    if(chunkLength != 2) return 30;

    color->key_defined = 1;
    color->key_r = color->key_g = color->key_b = 256u * data[0] + data[1];
  }
  else if(color->colortype == LCT_RGB)
  {
    /*error: this chunk must be 6 bytes for RGB image*/
    if(chunkLength != 6) return 41;

    color->key_defined = 1;
    color->key_r = 256u * data[0] + data[1];
    color->key_g = 256u * data[2] + data[3];
    color->key_b = 256u * data[4] + data[5];
  }
  else return 42; /*error: tRNS chunk not allowed for other color models*/

  return 0; /* OK */
}


#ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
/*background color chunk (bKGD)*/
static unsigned readChunk_bKGD(LodePNGInfo* info, const unsigned char* data, size_t chunkLength)
{
  if(info->color.colortype == LCT_PALETTE)
  {
    /*error: this chunk must be 1 byte for indexed color image*/
    if(chunkLength != 1) return 43;

    info->background_defined = 1;
    info->background_r = info->background_g = info->background_b = data[0];
  }
  else if(info->color.colortype == LCT_GREY || info->color.colortype == LCT_GREY_ALPHA)
  {
    /*error: this chunk must be 2 bytes for greyscale image*/
    if(chunkLength != 2) return 44;

    info->background_defined = 1;
    info->background_r = info->background_g = info->background_b = 256u * data[0] + data[1];
  }
  else if(info->color.colortype == LCT_RGB || info->color.colortype == LCT_RGBA)
  {
    /*error: this chunk must be 6 bytes for greyscale image*/
    if(chunkLength != 6) return 45;

    info->background_defined = 1;
    info->background_r = 256u * data[0] + data[1];
    info->background_g = 256u * data[2] + data[3];
    info->background_b = 256u * data[4] + data[5];
  }

  return 0; /* OK */
}

/*text chunk (tEXt)*/
static unsigned readChunk_tEXt(LodePNGInfo* info, const unsigned char* data, size_t chunkLength)
{
  unsigned error = 0;
  char *key = 0, *str = 0;
  unsigned i;

  while(!error) /*not really a while loop, only used to break on error*/
  {
    unsigned length, string2_begin;

    length = 0;
    while(length < chunkLength && data[length] != 0) ++length;
    /*even though it's not allowed by the standard, no error is thrown if
    there's no null termination char, if the text is empty*/
    if(length < 1 || length > 79) CERROR_BREAK(error, 89); /*keyword too short or long*/

    key = (char*)lodepng_malloc(length + 1);
    if(!key) CERROR_BREAK(error, 83); /*alloc fail*/

    key[length] = 0;
    for(i = 0; i != length; ++i) key[i] = (char)data[i];

    string2_begin = length + 1; /*skip keyword null terminator*/

    length = (unsigned)(chunkLength < string2_begin ? 0 : chunkLength - string2_begin);
    str = (char*)lodepng_malloc(length + 1);
    if(!str) CERROR_BREAK(error, 83); /*alloc fail*/

    str[length] = 0;
    for(i = 0; i != length; ++i) str[i] = (char)data[string2_begin + i];

    error = lodepng_add_text(info, key, str);

    break;
  }

  lodepng_free(key);
  lodepng_free(str);

  return error;
}

/*compressed text chunk (zTXt)*/
static unsigned readChunk_zTXt(LodePNGInfo* info, const LodePNGDecompressSettings* zlibsettings,
                               const unsigned char* data, size_t chunkLength)
{
  unsigned error = 0;
  unsigned i;

  unsigned length, string2_begin;
  char *key = 0;
  ucvector decoded;

  ucvector_init(&decoded);

  while(!error) /*not really a while loop, only used to break on error*/
  {
    for(length = 0; length < chunkLength && data[length] != 0; ++length) ;
    if(length + 2 >= chunkLength) CERROR_BREAK(error, 75); /*no null termination, corrupt?*/
    if(length < 1 || length > 79) CERROR_BREAK(error, 89); /*keyword too short or long*/

    key = (char*)lodepng_malloc(length + 1);
    if(!key) CERROR_BREAK(error, 83); /*alloc fail*/

    key[length] = 0;
    for(i = 0; i != length; ++i) key[i] = (char)data[i];

    if(data[length + 1] != 0) CERROR_BREAK(error, 72); /*the 0 byte indicating compression must be 0*/

    string2_begin = length + 2;
    if(string2_begin > chunkLength) CERROR_BREAK(error, 75); /*no null termination, corrupt?*/

    length = (unsigned)chunkLength - string2_begin;
    /*will fail if zlib error, e.g. if length is too small*/
    error = zlib_decompress(&decoded.data, &decoded.size,
                            (unsigned char*)(&data[string2_begin]),
                            length, zlibsettings);
    if(error) break;
    ucvector_push_back(&decoded, 0);

    error = lodepng_add_text(info, key, (char*)decoded.data);

    break;
  }

  lodepng_free(key);
  ucvector_cleanup(&decoded);

  return error;
}

/*international text chunk (iTXt)*/
static unsigned readChunk_iTXt(LodePNGInfo* info, const LodePNGDecompressSettings* zlibsettings,
                               const unsigned char* data, size_t chunkLength)
{
  unsigned error = 0;
  unsigned i;

  unsigned length, begin, compressed;
  char *key = 0, *langtag = 0, *transkey = 0;
  ucvector decoded;
  ucvector_init(&decoded);

  while(!error) /*not really a while loop, only used to break on error*/
  {
    /*Quick check if the chunk length isn't too small. Even without check
    it'd still fail with other error checks below if it's too short. This just gives a different error code.*/
    if(chunkLength < 5) CERROR_BREAK(error, 30); /*iTXt chunk too short*/

    /*read the key*/
    for(length = 0; length < chunkLength && data[length] != 0; ++length) ;
    if(length + 3 >= chunkLength) CERROR_BREAK(error, 75); /*no null termination char, corrupt?*/
    if(length < 1 || length > 79) CERROR_BREAK(error, 89); /*keyword too short or long*/

    key = (char*)lodepng_malloc(length + 1);
    if(!key) CERROR_BREAK(error, 83); /*alloc fail*/

    key[length] = 0;
    for(i = 0; i != length; ++i) key[i] = (char)data[i];

    /*read the compression method*/
    compressed = data[length + 1];
    if(data[length + 2] != 0) CERROR_BREAK(error, 72); /*the 0 byte indicating compression must be 0*/

    /*even though it's not allowed by the standard, no error is thrown if
    there's no null termination char, if the text is empty for the next 3 texts*/

    /*read the langtag*/
    begin = length + 3;
    length = 0;
    for(i = begin; i < chunkLength && data[i] != 0; ++i) ++length;

    langtag = (char*)lodepng_malloc(length + 1);
    if(!langtag) CERROR_BREAK(error, 83); /*alloc fail*/

    langtag[length] = 0;
    for(i = 0; i != length; ++i) langtag[i] = (char)data[begin + i];

    /*read the transkey*/
    begin += length + 1;
    length = 0;
    for(i = begin; i < chunkLength && data[i] != 0; ++i) ++length;

    transkey = (char*)lodepng_malloc(length + 1);
    if(!transkey) CERROR_BREAK(error, 83); /*alloc fail*/

    transkey[length] = 0;
    for(i = 0; i != length; ++i) transkey[i] = (char)data[begin + i];

    /*read the actual text*/
    begin += length + 1;

    length = (unsigned)chunkLength < begin ? 0 : (unsigned)chunkLength - begin;

    if(compressed)
    {
      /*will fail if zlib error, e.g. if length is too small*/
      error = zlib_decompress(&decoded.data, &decoded.size,
                              (unsigned char*)(&data[begin]),
                              length, zlibsettings);
      if(error) break;
      if(decoded.allocsize < decoded.size) decoded.allocsize = decoded.size;
      ucvector_push_back(&decoded, 0);
    }
    else
    {
      if(!ucvector_resize(&decoded, length + 1)) CERROR_BREAK(error, 83 /*alloc fail*/);

      decoded.data[length] = 0;
      for(i = 0; i != length; ++i) decoded.data[i] = data[begin + i];
    }

    error = lodepng_add_itext(info, key, langtag, transkey, (char*)decoded.data);

    break;
  }

  lodepng_free(key);
  lodepng_free(langtag);
  lodepng_free(transkey);
  ucvector_cleanup(&decoded);

  return error;
}

static unsigned readChunk_tIME(LodePNGInfo* info, const unsigned char* data, size_t chunkLength)
{
  if(chunkLength != 7) return 73; /*invalid tIME chunk size*/

  info->time_defined = 1;
  info->time.year = 256u * data[0] + data[1];
  info->time.month = data[2];
  info->time.day = data[3];
  info->time.hour = data[4];
  info->time.minute = data[5];
  info->time.second = data[6];

  return 0; /* OK */
}

static unsigned readChunk_pHYs(LodePNGInfo* info, const unsigned char* data, size_t chunkLength)
{
  if(chunkLength != 9) return 74; /*invalid pHYs chunk size*/

  info->phys_defined = 1;
  info->phys_x = 16777216u * data[0] + 65536u * data[1] + 256u * data[2] + data[3];
  info->phys_y = 16777216u * data[4] + 65536u * data[5] + 256u * data[6] + data[7];
  info->phys_unit = data[8];

  return 0; /* OK */
}
#endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/

/*read a PNG, the result will be in the same color type as the PNG (hence "generic")*/
static void decodeGeneric(unsigned char** out, unsigned* w, unsigned* h,
                          LodePNGState* state,
                          const unsigned char* in, size_t insize)
{
  unsigned char IEND = 0;
  const unsigned char* chunk;
  size_t i;
  ucvector idat; /*the data from idat chunks*/
  ucvector scanlines;
  size_t predict;
  size_t outsize = 0;

  /*for unknown chunk order*/
  unsigned unknown = 0;
#ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
  unsigned critical_pos = 1; /*1 = after IHDR, 2 = after PLTE, 3 = after IDAT*/
#endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/

  /*provide some proper output values if error will happen*/
  *out = 0;

  state->error = lodepng_inspect(w, h, state, in, insize); /*reads header and resets other parameters in state->info_png*/
  if(state->error) return;

  if(lodepng_pixel_overflow(*w, *h, &state->info_png.color, &state->info_raw))
  {
    CERROR_RETURN(state->error, 92); /*overflow possible due to amount of pixels*/
  }

  ucvector_init(&idat);
  chunk = &in[33]; /*first byte of the first chunk after the header*/

  /*loop through the chunks, ignoring unknown chunks and stopping at IEND chunk.
  IDAT data is put at the start of the in buffer*/
  while(!IEND && !state->error)
  {
    unsigned chunkLength;
    const unsigned char* data; /*the data in the chunk*/

    /*error: size of the in buffer too small to contain next chunk*/
    if((size_t)((chunk - in) + 12) > insize || chunk < in)
    {
      if(state->decoder.ignore_end) break; /*other errors may still happen though*/
      CERROR_BREAK(state->error, 30);
    }

    /*length of the data of the chunk, excluding the length bytes, chunk type and CRC bytes*/
    chunkLength = lodepng_chunk_length(chunk);
    /*error: chunk length larger than the max PNG chunk size*/
    if(chunkLength > 2147483647)
    {
      if(state->decoder.ignore_end) break; /*other errors may still happen though*/
      CERROR_BREAK(state->error, 63);
    }

    if((size_t)((chunk - in) + chunkLength + 12) > insize || (chunk + chunkLength + 12) < in)
    {
      CERROR_BREAK(state->error, 64); /*error: size of the in buffer too small to contain next chunk*/
    }

    data = lodepng_chunk_data_const(chunk);

    /*IDAT chunk, containing compressed image data*/
    if(lodepng_chunk_type_equals(chunk, "IDAT"))
    {
      size_t oldsize = idat.size;
      size_t newsize;
      if(lodepng_addofl(oldsize, chunkLength, &newsize)) CERROR_BREAK(state->error, 95);
      if(!ucvector_resize(&idat, newsize)) CERROR_BREAK(state->error, 83 /*alloc fail*/);
      for(i = 0; i != chunkLength; ++i) idat.data[oldsize + i] = data[i];
#ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
      critical_pos = 3;
#endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/
    }
    /*IEND chunk*/
    else if(lodepng_chunk_type_equals(chunk, "IEND"))
    {
      IEND = 1;
    }
    /*palette chunk (PLTE)*/
    else if(lodepng_chunk_type_equals(chunk, "PLTE"))
    {
      state->error = readChunk_PLTE(&state->info_png.color, data, chunkLength);
      if(state->error) break;
#ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
      critical_pos = 2;
#endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/
    }
    /*palette transparency chunk (tRNS)*/
    else if(lodepng_chunk_type_equals(chunk, "tRNS"))
    {
      state->error = readChunk_tRNS(&state->info_png.color, data, chunkLength);
      if(state->error) break;
    }
#ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
    /*background color chunk (bKGD)*/
    else if(lodepng_chunk_type_equals(chunk, "bKGD"))
    {
      state->error = readChunk_bKGD(&state->info_png, data, chunkLength);
      if(state->error) break;
    }
    /*text chunk (tEXt)*/
    else if(lodepng_chunk_type_equals(chunk, "tEXt"))
    {
      if(state->decoder.read_text_chunks)
      {
        state->error = readChunk_tEXt(&state->info_png, data, chunkLength);
        if(state->error) break;
      }
    }
    /*compressed text chunk (zTXt)*/
    else if(lodepng_chunk_type_equals(chunk, "zTXt"))
    {
      if(state->decoder.read_text_chunks)
      {
        state->error = readChunk_zTXt(&state->info_png, &state->decoder.zlibsettings, data, chunkLength);
        if(state->error) break;
      }
    }
    /*international text chunk (iTXt)*/
    else if(lodepng_chunk_type_equals(chunk, "iTXt"))
    {
      if(state->decoder.read_text_chunks)
      {
        state->error = readChunk_iTXt(&state->info_png, &state->decoder.zlibsettings, data, chunkLength);
        if(state->error) break;
      }
    }
    else if(lodepng_chunk_type_equals(chunk, "tIME"))
    {
      state->error = readChunk_tIME(&state->info_png, data, chunkLength);
      if(state->error) break;
    }
    else if(lodepng_chunk_type_equals(chunk, "pHYs"))
    {
      state->error = readChunk_pHYs(&state->info_png, data, chunkLength);
      if(state->error) break;
    }
#endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/
    else /*it's not an implemented chunk type, so ignore it: skip over the data*/
    {
      /*error: unknown critical chunk (5th bit of first byte of chunk type is 0)*/
      if(!state->decoder.ignore_critical && !lodepng_chunk_ancillary(chunk))
      {
        CERROR_BREAK(state->error, 69);
      }

      unknown = 1;
#ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
      if(state->decoder.remember_unknown_chunks)
      {
        state->error = lodepng_chunk_append(&state->info_png.unknown_chunks_data[critical_pos - 1],
                                            &state->info_png.unknown_chunks_size[critical_pos - 1], chunk);
        if(state->error) break;
      }
#endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/
    }

    if(!state->decoder.ignore_crc && !unknown) /*check CRC if wanted, only on known chunk types*/
    {
      if(lodepng_chunk_check_crc(chunk)) CERROR_BREAK(state->error, 57); /*invalid CRC*/
    }

    if(!IEND) chunk = lodepng_chunk_next_const(chunk);
  }

  ucvector_init(&scanlines);
  /*predict output size, to allocate exact size for output buffer to avoid more dynamic allocation.
  If the decompressed size does not match the prediction, the image must be corrupt.*/
  if(state->info_png.interlace_method == 0)
  {
    predict = lodepng_get_raw_size_idat(*w, *h, &state->info_png.color);
  }
  else
  {
    /*Adam-7 interlaced: predicted size is the sum of the 7 sub-images sizes*/
    const LodePNGColorMode* color = &state->info_png.color;
    predict = 0;
    predict += lodepng_get_raw_size_idat((*w + 7) >> 3, (*h + 7) >> 3, color);
    if(*w > 4) predict += lodepng_get_raw_size_idat((*w + 3) >> 3, (*h + 7) >> 3, color);
    predict += lodepng_get_raw_size_idat((*w + 3) >> 2, (*h + 3) >> 3, color);
    if(*w > 2) predict += lodepng_get_raw_size_idat((*w + 1) >> 2, (*h + 3) >> 2, color);
    predict += lodepng_get_raw_size_idat((*w + 1) >> 1, (*h + 1) >> 2, color);
    if(*w > 1) predict += lodepng_get_raw_size_idat((*w + 0) >> 1, (*h + 1) >> 1, color);
    predict += lodepng_get_raw_size_idat((*w + 0), (*h + 0) >> 1, color);
  }
  if(!state->error && !ucvector_reserve(&scanlines, predict)) state->error = 83; /*alloc fail*/
  if(!state->error)
  {
    state->error = zlib_decompress(&scanlines.data, &scanlines.size, idat.data,
                                   idat.size, &state->decoder.zlibsettings);
    if(!state->error && scanlines.size != predict) state->error = 91; /*decompressed size doesn't match prediction*/
  }
  ucvector_cleanup(&idat);

  if(!state->error)
  {
    outsize = lodepng_get_raw_size(*w, *h, &state->info_png.color);
    *out = (unsigned char*)lodepng_malloc(outsize);
    if(!*out) state->error = 83; /*alloc fail*/
  }
  if(!state->error)
  {
    for(i = 0; i < outsize; i++) (*out)[i] = 0;
    state->error = postProcessScanlines(*out, scanlines.data, *w, *h, &state->info_png);
  }
  ucvector_cleanup(&scanlines);
}

unsigned lodepng_decode(unsigned char** out, unsigned* w, unsigned* h,
                        LodePNGState* state,
                        const unsigned char* in, size_t insize)
{
  *out = 0;
  decodeGeneric(out, w, h, state, in, insize);
  if(state->error) return state->error;
  if(!state->decoder.color_convert || lodepng_color_mode_equal(&state->info_raw, &state->info_png.color))
  {
    /*same color type, no copying or converting of data needed*/
    /*store the info_png color settings on the info_raw so that the info_raw still reflects what colortype
    the raw image has to the end user*/
    if(!state->decoder.color_convert)
    {
      state->error = lodepng_color_mode_copy(&state->info_raw, &state->info_png.color);
      if(state->error) return state->error;
    }
  }
  else
  {
    /*color conversion needed; sort of copy of the data*/
    unsigned char* data = *out;
    size_t outsize;

    /*TODO: check if this works according to the statement in the documentation: "The converter can convert
    from greyscale input color type, to 8-bit greyscale or greyscale with alpha"*/
    if(!(state->info_raw.colortype == LCT_RGB || state->info_raw.colortype == LCT_RGBA)
       && !(state->info_raw.bitdepth == 8))
    {
      return 56; /*unsupported color mode conversion*/
    }

    outsize = lodepng_get_raw_size(*w, *h, &state->info_raw);
    *out = (unsigned char*)lodepng_malloc(outsize);
    if(!(*out))
    {
      state->error = 83; /*alloc fail*/
    }
    else state->error = lodepng_convert(*out, data, &state->info_raw,
                                        &state->info_png.color, *w, *h);
    lodepng_free(data);
  }
  return state->error;
}

unsigned lodepng_decode_memory(unsigned char** out, unsigned* w, unsigned* h, const unsigned char* in,
                               size_t insize, LodePNGColorType colortype, unsigned bitdepth)
{
  unsigned error;
  LodePNGState state;
  lodepng_state_init(&state);
  state.info_raw.colortype = colortype;
  state.info_raw.bitdepth = bitdepth;
  error = lodepng_decode(out, w, h, &state, in, insize);
  lodepng_state_cleanup(&state);
  return error;
}

unsigned lodepng_decode32(unsigned char** out, unsigned* w, unsigned* h, const unsigned char* in, size_t insize)
{
  return lodepng_decode_memory(out, w, h, in, insize, LCT_RGBA, 8);
}

unsigned lodepng_decode24(unsigned char** out, unsigned* w, unsigned* h, const unsigned char* in, size_t insize)
{
  return lodepng_decode_memory(out, w, h, in, insize, LCT_RGB, 8);
}

#ifdef LODEPNG_COMPILE_DISK
unsigned lodepng_decode_file(unsigned char** out, unsigned* w, unsigned* h, const char* filename,
                             LodePNGColorType colortype, unsigned bitdepth)
{
  unsigned char* buffer = 0;
  size_t buffersize;
  unsigned error;
  error = lodepng_load_file(&buffer, &buffersize, filename);
  if(!error) error = lodepng_decode_memory(out, w, h, buffer, buffersize, colortype, bitdepth);
  lodepng_free(buffer);
  return error;
}

unsigned lodepng_decode32_file(unsigned char** out, unsigned* w, unsigned* h, const char* filename)
{
  return lodepng_decode_file(out, w, h, filename, LCT_RGBA, 8);
}

unsigned lodepng_decode24_file(unsigned char** out, unsigned* w, unsigned* h, const char* filename)
{
  return lodepng_decode_file(out, w, h, filename, LCT_RGB, 8);
}
#endif /*LODEPNG_COMPILE_DISK*/

void lodepng_decoder_settings_init(LodePNGDecoderSettings* settings)
{
  settings->color_convert = 1;
#ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
  settings->read_text_chunks = 1;
  settings->remember_unknown_chunks = 0;
#endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/
  settings->ignore_crc = 0;
  settings->ignore_critical = 0;
  settings->ignore_end = 0;
  lodepng_decompress_settings_init(&settings->zlibsettings);
}

#endif /*LODEPNG_COMPILE_DECODER*/

#if defined(LODEPNG_COMPILE_DECODER) || defined(LODEPNG_COMPILE_ENCODER)

void lodepng_state_init(LodePNGState* state)
{
#ifdef LODEPNG_COMPILE_DECODER
  lodepng_decoder_settings_init(&state->decoder);
#endif /*LODEPNG_COMPILE_DECODER*/
#ifdef LODEPNG_COMPILE_ENCODER
  lodepng_encoder_settings_init(&state->encoder);
#endif /*LODEPNG_COMPILE_ENCODER*/
  lodepng_color_mode_init(&state->info_raw);
  lodepng_info_init(&state->info_png);
  state->error = 1;
}

void lodepng_state_cleanup(LodePNGState* state)
{
  lodepng_color_mode_cleanup(&state->info_raw);
  lodepng_info_cleanup(&state->info_png);
}

void lodepng_state_copy(LodePNGState* dest, const LodePNGState* source)
{
  lodepng_state_cleanup(dest);
  *dest = *source;
  lodepng_color_mode_init(&dest->info_raw);
  lodepng_info_init(&dest->info_png);
  dest->error = lodepng_color_mode_copy(&dest->info_raw, &source->info_raw); if(dest->error) return;
  dest->error = lodepng_info_copy(&dest->info_png, &source->info_png); if(dest->error) return;
}

#endif /* defined(LODEPNG_COMPILE_DECODER) || defined(LODEPNG_COMPILE_ENCODER) */

#ifdef LODEPNG_COMPILE_ENCODER

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

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

static void writeSignature(ucvector* out)
{
  /*8 bytes PNG signature, aka the magic bytes*/
  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,
                              LodePNGColorType colortype, unsigned bitdepth, unsigned interlace_method)
{
  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, interlace_method); /*interlace method*/

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

  return error;
}

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

  return error;
}

static unsigned addChunk_tRNS(ucvector* out, const LodePNGColorMode* info)
{
  unsigned error = 0;
  size_t i;
  ucvector tRNS;
  ucvector_init(&tRNS);
  if(info->colortype == LCT_PALETTE)
  {
    size_t amount = info->palettesize;
    /*the tail of palette values that all have 255 as alpha, does not have to be encoded*/
    for(i = info->palettesize; i != 0; --i)
    {
      if(info->palette[4 * (i - 1) + 3] == 255) --amount;
      else break;
    }
    /*add only alpha channel*/
    for(i = 0; i != amount; ++i) ucvector_push_back(&tRNS, info->palette[4 * i + 3]);
  }
  else if(info->colortype == LCT_GREY)
  {
    if(info->key_defined)
    {
      ucvector_push_back(&tRNS, (unsigned char)(info->key_r >> 8));
      ucvector_push_back(&tRNS, (unsigned char)(info->key_r & 255));
    }
  }
  else if(info->colortype == LCT_RGB)
  {
    if(info->key_defined)
    {
      ucvector_push_back(&tRNS, (unsigned char)(info->key_r >> 8));
      ucvector_push_back(&tRNS, (unsigned char)(info->key_r & 255));
      ucvector_push_back(&tRNS, (unsigned char)(info->key_g >> 8));
      ucvector_push_back(&tRNS, (unsigned char)(info->key_g & 255));
      ucvector_push_back(&tRNS, (unsigned char)(info->key_b >> 8));
      ucvector_push_back(&tRNS, (unsigned char)(info->key_b & 255));
    }
  }

  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,
                              LodePNGCompressSettings* zlibsettings)
{
  ucvector zlibdata;
  unsigned error = 0;

  /*compress with the Zlib compressor*/
  ucvector_init(&zlibdata);
  error = zlib_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;
}

#ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS

static unsigned addChunk_tEXt(ucvector* out, const char* keyword, const char* textstring)
{
  unsigned error = 0;
  size_t i;
  ucvector text;
  ucvector_init(&text);
  for(i = 0; keyword[i] != 0; ++i) ucvector_push_back(&text, (unsigned char)keyword[i]);
  if(i < 1 || i > 79) return 89; /*error: invalid keyword size*/
  ucvector_push_back(&text, 0); /*0 termination char*/
  for(i = 0; textstring[i] != 0; ++i) ucvector_push_back(&text, (unsigned char)textstring[i]);
  error = addChunk(out, "tEXt", text.data, text.size);
  ucvector_cleanup(&text);

  return error;
}

static unsigned addChunk_zTXt(ucvector* out, const char* keyword, const char* textstring,
                              LodePNGCompressSettings* zlibsettings)
{
  unsigned error = 0;
  ucvector data, compressed;
  size_t i, textsize = strlen(textstring);

  ucvector_init(&data);
  ucvector_init(&compressed);
  for(i = 0; keyword[i] != 0; ++i) ucvector_push_back(&data, (unsigned char)keyword[i]);
  if(i < 1 || i > 79) return 89; /*error: invalid keyword size*/
  ucvector_push_back(&data, 0); /*0 termination char*/
  ucvector_push_back(&data, 0); /*compression method: 0*/

  error = zlib_compress(&compressed.data, &compressed.size,
                        (unsigned char*)textstring, textsize, zlibsettings);
  if(!error)
  {
    for(i = 0; i != compressed.size; ++i) ucvector_push_back(&data, compressed.data[i]);
    error = addChunk(out, "zTXt", data.data, data.size);
  }

  ucvector_cleanup(&compressed);
  ucvector_cleanup(&data);
  return error;
}

static unsigned addChunk_iTXt(ucvector* out, unsigned compressed, const char* keyword, const char* langtag,
                              const char* transkey, const char* textstring, LodePNGCompressSettings* zlibsettings)
{
  unsigned error = 0;
  ucvector data;
  size_t i, textsize = strlen(textstring);

  ucvector_init(&data);

  for(i = 0; keyword[i] != 0; ++i) ucvector_push_back(&data, (unsigned char)keyword[i]);
  if(i < 1 || i > 79) return 89; /*error: invalid keyword size*/
  ucvector_push_back(&data, 0); /*null termination char*/
  ucvector_push_back(&data, compressed ? 1 : 0); /*compression flag*/
  ucvector_push_back(&data, 0); /*compression method*/
  for(i = 0; langtag[i] != 0; ++i) ucvector_push_back(&data, (unsigned char)langtag[i]);
  ucvector_push_back(&data, 0); /*null termination char*/
  for(i = 0; transkey[i] != 0; ++i) ucvector_push_back(&data, (unsigned char)transkey[i]);
  ucvector_push_back(&data, 0); /*null termination char*/

  if(compressed)
  {
    ucvector compressed_data;
    ucvector_init(&compressed_data);
    error = zlib_compress(&compressed_data.data, &compressed_data.size,
                          (unsigned char*)textstring, textsize, zlibsettings);
    if(!error)
    {
      for(i = 0; i != compressed_data.size; ++i) ucvector_push_back(&data, compressed_data.data[i]);
    }
    ucvector_cleanup(&compressed_data);
  }
  else /*not compressed*/
  {
    for(i = 0; textstring[i] != 0; ++i) ucvector_push_back(&data, (unsigned char)textstring[i]);
  }

  if(!error) error = addChunk(out, "iTXt", data.data, data.size);
  ucvector_cleanup(&data);
  return error;
}

static unsigned addChunk_bKGD(ucvector* out, const LodePNGInfo* info)
{
  unsigned error = 0;
  ucvector bKGD;
  ucvector_init(&bKGD);
  if(info->color.colortype == LCT_GREY || info->color.colortype == LCT_GREY_ALPHA)
  {
    ucvector_push_back(&bKGD, (unsigned char)(info->background_r >> 8));
    ucvector_push_back(&bKGD, (unsigned char)(info->background_r & 255));
  }
  else if(info->color.colortype == LCT_RGB || info->color.colortype == LCT_RGBA)
  {
    ucvector_push_back(&bKGD, (unsigned char)(info->background_r >> 8));
    ucvector_push_back(&bKGD, (unsigned char)(info->background_r & 255));
    ucvector_push_back(&bKGD, (unsigned char)(info->background_g >> 8));
    ucvector_push_back(&bKGD, (unsigned char)(info->background_g & 255));
    ucvector_push_back(&bKGD, (unsigned char)(info->background_b >> 8));
    ucvector_push_back(&bKGD, (unsigned char)(info->background_b & 255));
  }
  else if(info->color.colortype == LCT_PALETTE)
  {
    ucvector_push_back(&bKGD, (unsigned char)(info->background_r & 255)); /*palette index*/
  }

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

  return error;
}

static unsigned addChunk_tIME(ucvector* out, const LodePNGTime* time)
{
  unsigned error = 0;
  unsigned char* data = (unsigned char*)lodepng_malloc(7);
  if(!data) return 83; /*alloc fail*/
  data[0] = (unsigned char)(time->year >> 8);
  data[1] = (unsigned char)(time->year & 255);
  data[2] = (unsigned char)time->month;
  data[3] = (unsigned char)time->day;
  data[4] = (unsigned char)time->hour;
  data[5] = (unsigned char)time->minute;
  data[6] = (unsigned char)time->second;
  error = addChunk(out, "tIME", data, 7);
  lodepng_free(data);
  return error;
}

static unsigned addChunk_pHYs(ucvector* out, const LodePNGInfo* info)
{
  unsigned error = 0;
  ucvector data;
  ucvector_init(&data);

  lodepng_add32bitInt(&data, info->phys_x);
  lodepng_add32bitInt(&data, info->phys_y);
  ucvector_push_back(&data, info->phys_unit);

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

  return error;
}

#endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/

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: /*None*/
      for(i = 0; i != length; ++i) out[i] = scanline[i];
      break;
    case 1: /*Sub*/
      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: /*Up*/
      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: /*Average*/
      if(prevline)
      {
        for(i = 0; i != bytewidth; ++i) out[i] = scanline[i] - (prevline[i] >> 1);
        for(i = bytewidth; i < length; ++i) out[i] = scanline[i] - ((scanline[i - bytewidth] + prevline[i]) >> 1);
      }
      else
      {
        for(i = 0; i != bytewidth; ++i) out[i] = scanline[i];
        for(i = bytewidth; i < length; ++i) out[i] = scanline[i] - (scanline[i - bytewidth] >> 1);
      }
      break;
    case 4: /*Paeth*/
      if(prevline)
      {
        /*paethPredictor(0, prevline[i], 0) is always prevline[i]*/
        for(i = 0; i != bytewidth; ++i) out[i] = (scanline[i] - prevline[i]);
        for(i = bytewidth; i < length; ++i)
        {
          out[i] = (scanline[i] - paethPredictor(scanline[i - bytewidth], prevline[i], prevline[i - bytewidth]));
        }
      }
      else
      {
        for(i = 0; i != bytewidth; ++i) out[i] = scanline[i];
        /*paethPredictor(scanline[i - bytewidth], 0, 0) is always scanline[i - bytewidth]*/
        for(i = bytewidth; i < length; ++i) out[i] = (scanline[i] - scanline[i - bytewidth]);
      }
      break;
    default: return; /*unexisting filter type given*/
  }
}

/* log2 approximation. A slight bit faster than std::log. */
static float flog2(float f)
{
  float result = 0;
  while(f > 32) { result += 4; f /= 16; }
  while(f > 2) { ++result; f /= 2; }
  return result + 1.442695f * (f * f * f / 3 - 3 * f * f / 2 + 3 * f - 1.83333f);
}

static unsigned filter(unsigned char* out, const unsigned char* in, unsigned w, unsigned h,
                       const LodePNGColorMode* info, const LodePNGEncoderSettings* settings)
{
  /*
  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
  */

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

  /*
  There is a heuristic called the minimum sum of absolute differences heuristic, suggested by the PNG standard:
   *  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.
  This heuristic is used if filter strategy is LFS_MINSUM and filter_palette_zero is true.

  If filter_palette_zero is true and filter_strategy is not LFS_MINSUM, the above heuristic is followed,
  but for "the other case", whatever strategy filter_strategy is set to instead of the minimum sum
  heuristic is used.
  */
  if(settings->filter_palette_zero &&
     (info->colortype == LCT_PALETTE || info->bitdepth < 8)) strategy = LFS_ZERO;

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

  if(strategy == LFS_ZERO)
  {
    for(y = 0; y != h; ++y)
    {
      size_t outindex = (1 + linebytes) * y; /*the extra filterbyte added to each row*/
      size_t inindex = linebytes * y;
      out[outindex] = 0; /*filter type byte*/
      filterScanline(&out[outindex + 1], &in[inindex], prevline, linebytes, bytewidth, 0);
      prevline = &in[inindex];
    }
  }
  else if(strategy == LFS_MINSUM)
  {
    /*adaptive filtering*/
    size_t sum[5];
    unsigned char* attempt[5]; /*five filtering attempts, one for each filter type*/
    size_t smallest = 0;
    unsigned char type, bestType = 0;

    for(type = 0; type != 5; ++type)
    {
      attempt[type] = (unsigned char*)lodepng_malloc(linebytes);
      if(!attempt[type]) return 83; /*alloc fail*/
    }

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

          /*calculate the sum of the result*/
          sum[type] = 0;
          if(type == 0)
          {
            for(x = 0; x != linebytes; ++x) sum[type] += (unsigned char)(attempt[type][x]);
          }
          else
          {
            for(x = 0; x != linebytes; ++x)
            {
              /*For differences, each byte should be treated as signed, values above 127 are negative
              (converted to signed char). Filtertype 0 isn't a difference though, so use unsigned there.
              This means filtertype 0 is almost never chosen, but that is justified.*/
              unsigned char s = attempt[type][x];
              sum[type] += s < 128 ? s : (255U - s);
            }
          }

          /*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][x];
      }
    }

    for(type = 0; type != 5; ++type) lodepng_free(attempt[type]);
  }
  else if(strategy == LFS_ENTROPY)
  {
    float sum[5];
    unsigned char* attempt[5]; /*five filtering attempts, one for each filter type*/
    float smallest = 0;
    unsigned type, bestType = 0;
    unsigned count[256];

    for(type = 0; type != 5; ++type)
    {
      attempt[type] = (unsigned char*)lodepng_malloc(linebytes);
      if(!attempt[type]) return 83; /*alloc fail*/
    }

    for(y = 0; y != h; ++y)
    {
      /*try the 5 filter types*/
      for(type = 0; type != 5; ++type)
      {
        filterScanline(attempt[type], &in[y * linebytes], prevline, linebytes, bytewidth, type);
        for(x = 0; x != 256; ++x) count[x] = 0;
        for(x = 0; x != linebytes; ++x) ++count[attempt[type][x]];
        ++count[type]; /*the filter type itself is part of the scanline*/
        sum[type] = 0;
        for(x = 0; x != 256; ++x)
        {
          float p = count[x] / (float)(linebytes + 1);
          sum[type] += count[x] == 0 ? 0 : flog2(1 / p) * p;
        }
        /*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][x];
    }

    for(type = 0; type != 5; ++type) lodepng_free(attempt[type]);
  }
  else if(strategy == LFS_PREDEFINED)
  {
    for(y = 0; y != h; ++y)
    {
      size_t outindex = (1 + linebytes) * y; /*the extra filterbyte added to each row*/
      size_t inindex = linebytes * y;
      unsigned char type = settings->predefined_filters[y];
      out[outindex] = type; /*filter type byte*/
      filterScanline(&out[outindex + 1], &in[inindex], prevline, linebytes, bytewidth, type);
      prevline = &in[inindex];
    }
  }
  else if(strategy == LFS_BRUTE_FORCE)
  {
    /*brute force filter chooser.
    deflate the scanline after every filter attempt to see which one deflates best.
    This is very slow and gives only slightly smaller, sometimes even larger, result*/
    size_t size[5];
    unsigned char* attempt[5]; /*five filtering attempts, one for each filter type*/
    size_t smallest = 0;
    unsigned type = 0, bestType = 0;
    unsigned char* dummy;
    LodePNGCompressSettings zlibsettings = settings->zlibsettings;
    /*use fixed tree on the attempts so that the tree is not adapted to the filtertype on purpose,
    to simulate the true case where the tree is the same for the whole image. Sometimes it gives
    better result with dynamic tree anyway. Using the fixed tree sometimes gives worse, but in rare
    cases better compression. It does make this a bit less slow, so it's worth doing this.*/
    zlibsettings.btype = 1;
    /*a custom encoder likely doesn't read the btype setting and is optimized for complete PNG
    images only, so disable it*/
    zlibsettings.custom_zlib = 0;
    zlibsettings.custom_deflate = 0;
    for(type = 0; type != 5; ++type)
    {
      attempt[type] = (unsigned char*)lodepng_malloc(linebytes);
      if(!attempt[type]) return 83; /*alloc fail*/
    }
    for(y = 0; y != h; ++y) /*try the 5 filter types*/
    {
      for(type = 0; type != 5; ++type)
      {
        unsigned testsize = (unsigned)linebytes;
        /*if(testsize > 8) testsize /= 8;*/ /*it already works good enough by testing a part of the row*/

        filterScanline(attempt[type], &in[y * linebytes], prevline, linebytes, bytewidth, type);
        size[type] = 0;
        dummy = 0;
        zlib_compress(&dummy, &size[type], attempt[type], testsize, &zlibsettings);
        lodepng_free(dummy);
        /*check if this is smallest size (or if type == 0 it's the first case so always store the values)*/
        if(type == 0 || size[type] < smallest)
        {
          bestType = type;
          smallest = size[type];
        }
      }
      prevline = &in[y * linebytes];
      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][x];
    }
    for(type = 0; type != 5; ++type) lodepng_free(attempt[type]);
  }
  else return 88; /* unknown filter strategy */

  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);
  }
}

/*
in: non-interlaced image with size w*h
out: the same pixels, but re-ordered according to PNG's Adam7 interlacing, with
 no padding bits between scanlines, but between reduced images so that each
 reduced image starts at a byte.
bpp: bits per pixel
there are no padding bits, not between scanlines, not between reduced images
in has the following size in bits: w * h * bpp.
out is possibly bigger due to padding bits between reduced images
NOTE: comments about padding bits are only relevant if bpp < 8
*/
static void Adam7_interlace(unsigned char* out, const unsigned char* in, unsigned w, unsigned h, unsigned bpp)
{
  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.
return value is error**/
static unsigned preProcessScanlines(unsigned char** out, size_t* outsize, const unsigned char* in,
                                    unsigned w, unsigned h,
                                    const LodePNGInfo* info_png, const LodePNGEncoderSettings* settings)
{
  /*
  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 (= posible 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_get_bpp(&info_png->color);
  unsigned error = 0;

  if(info_png->interlace_method == 0)
  {
    *outsize = h + (h * ((w * bpp + 7) / 8)); /*image size plus an extra byte per scanline + possible padding bits*/
    *out = (unsigned char*)lodepng_malloc(*outsize);
    if(!(*out) && (*outsize)) error = 83; /*alloc fail*/

    if(!error)
    {
      /*non multiple of 8 bits per scanline, padding bits needed per scanline*/
      if(bpp < 8 && w * bpp != ((w * bpp + 7) / 8) * 8)
      {
        unsigned char* padded = (unsigned char*)lodepng_malloc(h * ((w * bpp + 7) / 8));
        if(!padded) error = 83; /*alloc fail*/
        if(!error)
        {
          addPaddingBits(padded, in, ((w * bpp + 7) / 8) * 8, w * bpp, h);
          error = filter(*out, padded, w, h, &info_png->color, settings);
        }
        lodepng_free(padded);
      }
      else
      {
        /*we can immediately filter into the out buffer, no other steps needed*/
        error = filter(*out, in, w, h, &info_png->color, settings);
      }
    }
  }
  else /*interlace_method is 1 (Adam7)*/
  {
    unsigned passw[7], passh[7];
    size_t filter_passstart[8], padded_passstart[8], passstart[8];
    unsigned char* adam7;

    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*)lodepng_malloc(*outsize);
    if(!(*out)) error = 83; /*alloc fail*/

    adam7 = (unsigned char*)lodepng_malloc(passstart[7]);
    if(!adam7 && passstart[7]) error = 83; /*alloc fail*/

    if(!error)
    {
      unsigned i;

      Adam7_interlace(adam7, in, w, h, bpp);
      for(i = 0; i != 7; ++i)
      {
        if(bpp < 8)
        {
          unsigned char* padded = (unsigned char*)lodepng_malloc(padded_passstart[i + 1] - padded_passstart[i]);
          if(!padded) ERROR_BREAK(83); /*alloc fail*/
          addPaddingBits(padded, &adam7[passstart[i]],
                         ((passw[i] * bpp + 7) / 8) * 8, passw[i] * bpp, passh[i]);
          error = filter(&(*out)[filter_passstart[i]], padded,
                         passw[i], passh[i], &info_png->color, settings);
          lodepng_free(padded);
        }
        else
        {
          error = filter(&(*out)[filter_passstart[i]], &adam7[padded_passstart[i]],
                         passw[i], passh[i], &info_png->color, settings);
        }

        if(error) break;
      }
    }

    lodepng_free(adam7);
  }

  return error;
}

/*
palette must have 4 * palettesize bytes allocated, and given in format RGBARGBARGBARGBA...
returns 0 if the palette is opaque,
returns 1 if the palette has a single color with alpha 0 ==> color key
returns 2 if the palette is semi-translucent.
*/
static unsigned getPaletteTranslucency(const unsigned char* palette, size_t palettesize)
{
  size_t i;
  unsigned key = 0;
  unsigned r = 0, g = 0, b = 0; /*the value of the color with alpha 0, so long as color keying is possible*/
  for(i = 0; i != palettesize; ++i)
  {
    if(!key && palette[4 * i + 3] == 0)
    {
      r = palette[4 * i + 0]; g = palette[4 * i + 1]; b = palette[4 * i + 2];
      key = 1;
      i = (size_t)(-1); /*restart from beginning, to detect earlier opaque colors with key's value*/
    }
    else if(palette[4 * i + 3] != 255) return 2;
    /*when key, no opaque RGB may have key's RGB*/
    else if(key && r == palette[i * 4 + 0] && g == palette[i * 4 + 1] && b == palette[i * 4 + 2]) return 2;
  }
  return key;
}

#ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
static unsigned addUnknownChunks(ucvector* out, unsigned char* data, size_t datasize)
{
  unsigned char* inchunk = data;
  while((size_t)(inchunk - data) < datasize)
  {
    CERROR_TRY_RETURN(lodepng_chunk_append(&out->data, &out->size, inchunk));
    out->allocsize = out->size; /*fix the allocsize again*/
    inchunk = lodepng_chunk_next(inchunk);
  }
  return 0;
}
#endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/

unsigned lodepng_encode(unsigned char** out, size_t* outsize,
                        const unsigned char* image, unsigned w, unsigned h,
                        LodePNGState* state)
{
  LodePNGInfo 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;
  state->error = 0;

  /*check input values validity*/
  if((state->info_png.color.colortype == LCT_PALETTE || state->encoder.force_palette)
      && (state->info_png.color.palettesize == 0 || state->info_png.color.palettesize > 256))
  {
    CERROR_RETURN_ERROR(state->error, 68); /*invalid palette size, it is only allowed to be 1-256*/
  }
  if(state->encoder.zlibsettings.btype > 2)
  {
    CERROR_RETURN_ERROR(state->error, 61); /*error: unexisting btype*/
  }
  if(state->info_png.interlace_method > 1)
  {
    CERROR_RETURN_ERROR(state->error, 71); /*error: unexisting interlace mode*/
  }
  state->error = checkColorValidity(state->info_png.color.colortype, state->info_png.color.bitdepth);
  if(state->error) return state->error; /*error: unexisting color type given*/
  state->error = checkColorValidity(state->info_raw.colortype, state->info_raw.bitdepth);
  if(state->error) return state->error; /*error: unexisting color type given*/

  /* color convert and compute scanline filter types */
  lodepng_info_init(&info);
  lodepng_info_copy(&info, &state->info_png);
  if(state->encoder.auto_convert)
  {
    state->error = lodepng_auto_choose_color(&info.color, image, w, h, &state->info_raw);
  }
  if (!state->error)
  {
    if(!lodepng_color_mode_equal(&state->info_raw, &info.color))
    {
      unsigned char* converted;
      size_t size = ((size_t)w * (size_t)h * (size_t)lodepng_get_bpp(&info.color) + 7) / 8;

      converted = (unsigned char*)lodepng_malloc(size);
      if(!converted && size) state->error = 83; /*alloc fail*/
      if(!state->error)
      {
        state->error = lodepng_convert(converted, image, &info.color, &state->info_raw, w, h);
      }
      if(!state->error) preProcessScanlines(&data, &datasize, converted, w, h, &info, &state->encoder);
      lodepng_free(converted);
    }
    else preProcessScanlines(&data, &datasize, image, w, h, &info, &state->encoder);
  }

  /* output all PNG chunks */
  ucvector_init(&outv);
  while(!state->error) /*while only executed once, to break on error*/
  {
#ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
    size_t i;
#endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/
    /*write signature and chunks*/
    writeSignature(&outv);
    /*IHDR*/
    addChunk_IHDR(&outv, w, h, info.color.colortype, info.color.bitdepth, info.interlace_method);
#ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
    /*unknown chunks between IHDR and PLTE*/
    if(info.unknown_chunks_data[0])
    {
      state->error = addUnknownChunks(&outv, info.unknown_chunks_data[0], info.unknown_chunks_size[0]);
      if(state->error) break;
    }
#endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/
    /*PLTE*/
    if(info.color.colortype == LCT_PALETTE)
    {
      addChunk_PLTE(&outv, &info.color);
    }
    if(state->encoder.force_palette && (info.color.colortype == LCT_RGB || info.color.colortype == LCT_RGBA))
    {
      addChunk_PLTE(&outv, &info.color);
    }
    /*tRNS*/
    if(info.color.colortype == LCT_PALETTE && getPaletteTranslucency(info.color.palette, info.color.palettesize) != 0)
    {
      addChunk_tRNS(&outv, &info.color);
    }
    if((info.color.colortype == LCT_GREY || info.color.colortype == LCT_RGB) && info.color.key_defined)
    {
      addChunk_tRNS(&outv, &info.color);
    }
#ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
    /*bKGD (must come between PLTE and the IDAt chunks*/
    if(info.background_defined) addChunk_bKGD(&outv, &info);
    /*pHYs (must come before the IDAT chunks)*/
    if(info.phys_defined) addChunk_pHYs(&outv, &info);

    /*unknown chunks between PLTE and IDAT*/
    if(info.unknown_chunks_data[1])
    {
      state->error = addUnknownChunks(&outv, info.unknown_chunks_data[1], info.unknown_chunks_size[1]);
      if(state->error) break;
    }
#endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/
    /*IDAT (multiple IDAT chunks must be consecutive)*/
    state->error = addChunk_IDAT(&outv, data, datasize, &state->encoder.zlibsettings);
    if(state->error) break;
#ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
    /*tIME*/
    if(info.time_defined) addChunk_tIME(&outv, &info.time);
    /*tEXt and/or zTXt*/
    for(i = 0; i != info.text_num; ++i)
    {
      if(strlen(info.text_keys[i]) > 79)
      {
        state->error = 66; /*text chunk too large*/
        break;
      }
      if(strlen(info.text_keys[i]) < 1)
      {
        state->error = 67; /*text chunk too small*/
        break;
      }
      if(state->encoder.text_compression)
      {
        addChunk_zTXt(&outv, info.text_keys[i], info.text_strings[i], &state->encoder.zlibsettings);
      }
      else
      {
        addChunk_tEXt(&outv, info.text_keys[i], info.text_strings[i]);
      }
    }
    /*LodePNG version id in text chunk*/
    if(state->encoder.add_id)
    {
      unsigned alread_added_id_text = 0;
      for(i = 0; i != info.text_num; ++i)
      {
        if(!strcmp(info.text_keys[i], "LodePNG"))
        {
          alread_added_id_text = 1;
          break;
        }
      }
      if(alread_added_id_text == 0)
      {
        addChunk_tEXt(&outv, "LodePNG", LODEPNG_VERSION_STRING); /*it's shorter as tEXt than as zTXt chunk*/
      }
    }
    /*iTXt*/
    for(i = 0; i != info.itext_num; ++i)
    {
      if(strlen(info.itext_keys[i]) > 79)
      {
        state->error = 66; /*text chunk too large*/
        break;
      }
      if(strlen(info.itext_keys[i]) < 1)
      {
        state->error = 67; /*text chunk too small*/
        break;
      }
      addChunk_iTXt(&outv, state->encoder.text_compression,
                    info.itext_keys[i], info.itext_langtags[i], info.itext_transkeys[i], info.itext_strings[i],
                    &state->encoder.zlibsettings);
    }

    /*unknown chunks between IDAT and IEND*/
    if(info.unknown_chunks_data[2])
    {
      state->error = addUnknownChunks(&outv, info.unknown_chunks_data[2], info.unknown_chunks_size[2]);
      if(state->error) break;
    }
#endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/
    addChunk_IEND(&outv);

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

  lodepng_info_cleanup(&info);
  lodepng_free(data);
  /*instead of cleaning the vector up, give it to the output*/
  *out = outv.data;
  *outsize = outv.size;

  return state->error;
}

unsigned lodepng_encode_memory(unsigned char** out, size_t* outsize, const unsigned char* image,
                               unsigned w, unsigned h, LodePNGColorType colortype, unsigned bitdepth)
{
  unsigned error;
  LodePNGState state;
  lodepng_state_init(&state);
  state.info_raw.colortype = colortype;
  state.info_raw.bitdepth = bitdepth;
  state.info_png.color.colortype = colortype;
  state.info_png.color.bitdepth = bitdepth;
  lodepng_encode(out, outsize, image, w, h, &state);
  error = state.error;
  lodepng_state_cleanup(&state);
  return error;
}

unsigned lodepng_encode32(unsigned char** out, size_t* outsize, const unsigned char* image, unsigned w, unsigned h)
{
  return lodepng_encode_memory(out, outsize, image, w, h, LCT_RGBA, 8);
}

unsigned lodepng_encode24(unsigned char** out, size_t* outsize, const unsigned char* image, unsigned w, unsigned h)
{
  return lodepng_encode_memory(out, outsize, image, w, h, LCT_RGB, 8);
}

#ifdef LODEPNG_COMPILE_DISK
unsigned lodepng_encode_file(const char* filename, const unsigned char* image, unsigned w, unsigned h,
                             LodePNGColorType colortype, unsigned bitdepth)
{
  unsigned char* buffer;
  size_t buffersize;
  unsigned error = lodepng_encode_memory(&buffer, &buffersize, image, w, h, colortype, bitdepth);
  if(!error) error = lodepng_save_file(buffer, buffersize, filename);
  lodepng_free(buffer);
  return error;
}

unsigned lodepng_encode32_file(const char* filename, const unsigned char* image, unsigned w, unsigned h)
{
  return lodepng_encode_file(filename, image, w, h, LCT_RGBA, 8);
}

unsigned lodepng_encode24_file(const char* filename, const unsigned char* image, unsigned w, unsigned h)
{
  return lodepng_encode_file(filename, image, w, h, LCT_RGB, 8);
}
#endif /*LODEPNG_COMPILE_DISK*/

void lodepng_encoder_settings_init(LodePNGEncoderSettings* settings)
{
  lodepng_compress_settings_init(&settings->zlibsettings);
  settings->filter_palette_zero = 1;
  settings->filter_strategy = LFS_MINSUM;
  settings->auto_convert = 1;
  settings->force_palette = 0;
  settings->predefined_filters = 0;
#ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
  settings->add_id = 0;
  settings->text_compression = 1;
#endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/
}

#endif /*LODEPNG_COMPILE_ENCODER*/
#endif /*LODEPNG_COMPILE_PNG*/

#ifdef LODEPNG_COMPILE_ERROR_TEXT
/*
This returns the description of a numerical error code in English. This is also
the documentation of all the error codes.
*/
const char* lodepng_error_text(unsigned code)
{
  switch(code)
  {
    case 0: return "no error, everything went ok";
    case 1: return "nothing done yet"; /*the Encoder/Decoder has done nothing yet, error checking makes no sense yet*/
    case 10: return "end of input memory reached without huffman end code"; /*while huffman decoding*/
    case 11: return "error in code tree made it jump outside of huffman tree"; /*while huffman decoding*/
    case 13: return "problem while processing dynamic deflate block";
    case 14: return "problem while processing dynamic deflate block";
    case 15: return "problem while processing dynamic deflate block";
    case 16: return "unexisting code while processing dynamic deflate block";
    case 17: return "end of out buffer memory reached while inflating";
    case 18: return "invalid distance code while inflating";
    case 19: return "end of out buffer memory reached while inflating";
    case 20: return "invalid deflate block BTYPE encountered while decoding";
    case 21: return "NLEN is not ones complement of LEN in a deflate block";
     /*end of out buffer memory reached while inflating:
     This can happen if the inflated deflate data is longer than the amount of bytes required to fill up
     all the pixels of the image, given the color depth and image dimensions. Something that doesn't
     happen in a normal, well encoded, PNG image.*/
    case 22: return "end of out buffer memory reached while inflating";
    case 23: return "end of in buffer memory reached while inflating";
    case 24: return "invalid FCHECK in zlib header";
    case 25: return "invalid compression method in zlib header";
    case 26: return "FDICT encountered in zlib header while it's not used for PNG";
    case 27: return "PNG file is smaller than a PNG header";
    /*Checks the magic file header, the first 8 bytes of the PNG file*/
    case 28: return "incorrect PNG signature, it's no PNG or corrupted";
    case 29: return "first chunk is not the header chunk";
    case 30: return "chunk length too large, chunk broken off at end of file";
    case 31: return "illegal PNG color type or bpp";
    case 32: return "illegal PNG compression method";
    case 33: return "illegal PNG filter method";
    case 34: return "illegal PNG interlace method";
    case 35: return "chunk length of a chunk is too large or the chunk too small";
    case 36: return "illegal PNG filter type encountered";
    case 37: return "illegal bit depth for this color type given";
    case 38: return "the palette is too big"; /*more than 256 colors*/
    case 39: return "more palette alpha values given in tRNS chunk than there are colors in the palette";
    case 40: return "tRNS chunk has wrong size for greyscale image";
    case 41: return "tRNS chunk has wrong size for RGB image";
    case 42: return "tRNS chunk appeared while it was not allowed for this color type";
    case 43: return "bKGD chunk has wrong size for palette image";
    case 44: return "bKGD chunk has wrong size for greyscale image";
    case 45: return "bKGD chunk has wrong size for RGB image";
    case 48: return "empty input buffer given to decoder. Maybe caused by non-existing file?";
    case 49: return "jumped past memory while generating dynamic huffman tree";
    case 50: return "jumped past memory while generating dynamic huffman tree";
    case 51: return "jumped past memory while inflating huffman block";
    case 52: return "jumped past memory while inflating";
    case 53: return "size of zlib data too small";
    case 54: return "repeat symbol in tree while there was no value symbol yet";
    /*jumped past tree while generating huffman tree, this could be when the
    tree will have more leaves than symbols after generating it out of the
    given lenghts. They call this an oversubscribed dynamic bit lengths tree in zlib.*/
    case 55: return "jumped past tree while generating huffman tree";
    case 56: return "given output image colortype or bitdepth not supported for color conversion";
    case 57: return "invalid CRC encountered (checking CRC can be disabled)";
    case 58: return "invalid ADLER32 encountered (checking ADLER32 can be disabled)";
    case 59: return "requested color conversion not supported";
    case 60: return "invalid window size given in the settings of the encoder (must be 0-32768)";
    case 61: return "invalid BTYPE given in the settings of the encoder (only 0, 1 and 2 are allowed)";
    /*LodePNG leaves the choice of RGB to greyscale conversion formula to the user.*/
    case 62: return "conversion from color to greyscale not supported";
    case 63: return "length of a chunk too long, max allowed for PNG is 2147483647 bytes per chunk"; /*(2^31-1)*/
    /*this would result in the inability of a deflated block to ever contain an end code. It must be at least 1.*/
    case 64: return "the length of the END symbol 256 in the Huffman tree is 0";
    case 66: return "the length of a text chunk keyword given to the encoder is longer than the maximum of 79 bytes";
    case 67: return "the length of a text chunk keyword given to the encoder is smaller than the minimum of 1 byte";
    case 68: return "tried to encode a PLTE chunk with a palette that has less than 1 or more than 256 colors";
    case 69: return "unknown chunk type with 'critical' flag encountered by the decoder";
    case 71: return "unexisting interlace mode given to encoder (must be 0 or 1)";
    case 72: return "while decoding, unexisting compression method encountering in zTXt or iTXt chunk (it must be 0)";
    case 73: return "invalid tIME chunk size";
    case 74: return "invalid pHYs chunk size";
    /*length could be wrong, or data chopped off*/
    case 75: return "no null termination char found while decoding text chunk";
    case 76: return "iTXt chunk too short to contain required bytes";
    case 77: return "integer overflow in buffer size";
    case 78: return "failed to open file for reading"; /*file doesn't exist or couldn't be opened for reading*/
    case 79: return "failed to open file for writing";
    case 80: return "tried creating a tree of 0 symbols";
    case 81: return "lazy matching at pos 0 is impossible";
    case 82: return "color conversion to palette requested while a color isn't in palette";
    case 83: return "memory allocation failed";
    case 84: return "given image too small to contain all pixels to be encoded";
    case 86: return "impossible offset in lz77 encoding (internal bug)";
    case 87: return "must provide custom zlib function pointer if LODEPNG_COMPILE_ZLIB is not defined";
    case 88: return "invalid filter strategy given for LodePNGEncoderSettings.filter_strategy";
    case 89: return "text chunk keyword too short or long: must have size 1-79";
    /*the windowsize in the LodePNGCompressSettings. Requiring POT(==> & instead of %) makes encoding 12% faster.*/
    case 90: return "windowsize must be a power of two";
    case 91: return "invalid decompressed idat size";
    case 92: return "integer overflow due to too many pixels";
    case 93: return "zero width or height is invalid";
    case 94: return "header chunk must have a size of 13 bytes";
    case 95: return "integer overflow with combined idat chunk size";
  }
  return "unknown error code";
}
#endif /*LODEPNG_COMPILE_ERROR_TEXT*/

/* ////////////////////////////////////////////////////////////////////////// */
/* ////////////////////////////////////////////////////////////////////////// */
/* // C++ Wrapper                                                          // */
/* ////////////////////////////////////////////////////////////////////////// */
/* ////////////////////////////////////////////////////////////////////////// */

#ifdef LODEPNG_COMPILE_CPP
namespace lodepng
{

#ifdef LODEPNG_COMPILE_DISK
unsigned load_file(std::vector<unsigned char>& buffer, const std::string& filename)
{
  long size = lodepng_filesize(filename.c_str());
  if(size < 0) return 78;
  buffer.resize((size_t)size);
  return size == 0 ? 0 : lodepng_buffer_file(&buffer[0], (size_t)size, filename.c_str());
}

/*write given buffer to the file, overwriting the file, it doesn't append to it.*/
unsigned save_file(const std::vector<unsigned char>& buffer, const std::string& filename)
{
  return lodepng_save_file(buffer.empty() ? 0 : &buffer[0], buffer.size(), filename.c_str());
}
#endif /* LODEPNG_COMPILE_DISK */

#ifdef LODEPNG_COMPILE_ZLIB
#ifdef LODEPNG_COMPILE_DECODER
unsigned decompress(std::vector<unsigned char>& out, const unsigned char* in, size_t insize,
                    const LodePNGDecompressSettings& settings)
{
  unsigned char* buffer = 0;
  size_t buffersize = 0;
  unsigned error = zlib_decompress(&buffer, &buffersize, in, insize, &settings);
  if(buffer)
  {
    out.insert(out.end(), &buffer[0], &buffer[buffersize]);
    lodepng_free(buffer);
  }
  return error;
}

unsigned decompress(std::vector<unsigned char>& out, const std::vector<unsigned char>& in,
                    const LodePNGDecompressSettings& settings)
{
  return decompress(out, in.empty() ? 0 : &in[0], in.size(), settings);
}
#endif /* LODEPNG_COMPILE_DECODER */

#ifdef LODEPNG_COMPILE_ENCODER
unsigned compress(std::vector<unsigned char>& out, const unsigned char* in, size_t insize,
                  const LodePNGCompressSettings& settings)
{
  unsigned char* buffer = 0;
  size_t buffersize = 0;
  unsigned error = zlib_compress(&buffer, &buffersize, in, insize, &settings);
  if(buffer)
  {
    out.insert(out.end(), &buffer[0], &buffer[buffersize]);
    lodepng_free(buffer);
  }
  return error;
}

unsigned compress(std::vector<unsigned char>& out, const std::vector<unsigned char>& in,
                  const LodePNGCompressSettings& settings)
{
  return compress(out, in.empty() ? 0 : &in[0], in.size(), settings);
}
#endif /* LODEPNG_COMPILE_ENCODER */
#endif /* LODEPNG_COMPILE_ZLIB */


#ifdef LODEPNG_COMPILE_PNG

State::State()
{
  lodepng_state_init(this);
}

State::State(const State& other)
{
  lodepng_state_init(this);
  lodepng_state_copy(this, &other);
}

State::~State()
{
  lodepng_state_cleanup(this);
}

State& State::operator=(const State& other)
{
  lodepng_state_copy(this, &other);
  return *this;
}

#ifdef LODEPNG_COMPILE_DECODER

unsigned decode(std::vector<unsigned char>& out, unsigned& w, unsigned& h, const unsigned char* in,
                size_t insize, LodePNGColorType colortype, unsigned bitdepth)
{
  unsigned char* buffer;
  unsigned error = lodepng_decode_memory(&buffer, &w, &h, in, insize, colortype, bitdepth);
  if(buffer && !error)
  {
    State state;
    state.info_raw.colortype = colortype;
    state.info_raw.bitdepth = bitdepth;
    size_t buffersize = lodepng_get_raw_size(w, h, &state.info_raw);
    out.insert(out.end(), &buffer[0], &buffer[buffersize]);
    lodepng_free(buffer);
  }
  return error;
}

unsigned decode(std::vector<unsigned char>& out, unsigned& w, unsigned& h,
                const std::vector<unsigned char>& in, LodePNGColorType colortype, unsigned bitdepth)
{
  return decode(out, w, h, in.empty() ? 0 : &in[0], (unsigned)in.size(), colortype, bitdepth);
}

unsigned decode(std::vector<unsigned char>& out, unsigned& w, unsigned& h,
                State& state,
                const unsigned char* in, size_t insize)
{
  unsigned char* buffer = NULL;
  unsigned error = lodepng_decode(&buffer, &w, &h, &state, in, insize);
  if(buffer && !error)
  {
    size_t buffersize = lodepng_get_raw_size(w, h, &state.info_raw);
    out.insert(out.end(), &buffer[0], &buffer[buffersize]);
  }
  lodepng_free(buffer);
  return error;
}

unsigned decode(std::vector<unsigned char>& out, unsigned& w, unsigned& h,
                State& state,
                const std::vector<unsigned char>& in)
{
  return decode(out, w, h, state, in.empty() ? 0 : &in[0], in.size());
}

#ifdef LODEPNG_COMPILE_DISK
unsigned decode(std::vector<unsigned char>& out, unsigned& w, unsigned& h, const std::string& filename,
                LodePNGColorType colortype, unsigned bitdepth)
{
  std::vector<unsigned char> buffer;
  unsigned error = load_file(buffer, filename);
  if(error) return error;
  return decode(out, w, h, buffer, colortype, bitdepth);
}
#endif /* LODEPNG_COMPILE_DECODER */
#endif /* LODEPNG_COMPILE_DISK */

#ifdef LODEPNG_COMPILE_ENCODER
unsigned encode(std::vector<unsigned char>& out, const unsigned char* in, unsigned w, unsigned h,
                LodePNGColorType colortype, unsigned bitdepth)
{
  unsigned char* buffer;
  size_t buffersize;
  unsigned error = lodepng_encode_memory(&buffer, &buffersize, in, w, h, colortype, bitdepth);
  if(buffer)
  {
    out.insert(out.end(), &buffer[0], &buffer[buffersize]);
    lodepng_free(buffer);
  }
  return error;
}

unsigned encode(std::vector<unsigned char>& out,
                const std::vector<unsigned char>& in, unsigned w, unsigned h,
                LodePNGColorType colortype, unsigned bitdepth)
{
  if(lodepng_get_raw_size_lct(w, h, colortype, bitdepth) > in.size()) return 84;
  return encode(out, in.empty() ? 0 : &in[0], w, h, colortype, bitdepth);
}

unsigned encode(std::vector<unsigned char>& out,
                const unsigned char* in, unsigned w, unsigned h,
                State& state)
{
  unsigned char* buffer;
  size_t buffersize;
  unsigned error = lodepng_encode(&buffer, &buffersize, in, w, h, &state);
  if(buffer)
  {
    out.insert(out.end(), &buffer[0], &buffer[buffersize]);
    lodepng_free(buffer);
  }
  return error;
}

unsigned encode(std::vector<unsigned char>& out,
                const std::vector<unsigned char>& in, unsigned w, unsigned h,
                State& state)
{
  if(lodepng_get_raw_size(w, h, &state.info_raw) > in.size()) return 84;
  return encode(out, in.empty() ? 0 : &in[0], w, h, state);
}

#ifdef LODEPNG_COMPILE_DISK
unsigned encode(const std::string& filename,
                const unsigned char* in, unsigned w, unsigned h,
                LodePNGColorType colortype, unsigned bitdepth)
{
  std::vector<unsigned char> buffer;
  unsigned error = encode(buffer, in, w, h, colortype, bitdepth);
  if(!error) error = save_file(buffer, filename);
  return error;
}

unsigned encode(const std::string& filename,
                const std::vector<unsigned char>& in, unsigned w, unsigned h,
                LodePNGColorType colortype, unsigned bitdepth)
{
  if(lodepng_get_raw_size_lct(w, h, colortype, bitdepth) > in.size()) return 84;
  return encode(filename, in.empty() ? 0 : &in[0], w, h, colortype, bitdepth);
}
#endif /* LODEPNG_COMPILE_DISK */
#endif /* LODEPNG_COMPILE_ENCODER */
#endif /* LODEPNG_COMPILE_PNG */
} /* namespace lodepng */
#endif /*LODEPNG_COMPILE_CPP*/