summaryrefslogtreecommitdiff
path: root/archival/gzip.c
blob: bc1f9c60b5f160f311f6f969c5efbdc26d0e085a (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
/* vi: set sw=4 ts=4: */
/*
 * Gzip implementation for busybox
 *
 * Based on GNU gzip Copyright (C) 1992-1993 Jean-loup Gailly.
 *
 * Originally adjusted for busybox by Charles P. Wright <cpw@unix.asb.com>
 * "this is a stripped down version of gzip I put into busybox, it does
 * only standard in to standard out with -9 compression.  It also requires
 * the zcat module for some important functions."
 *
 * Adjusted further by Erik Andersen <andersen@codepoet.org> to support
 * files as well as stdin/stdout, and to generally behave itself wrt
 * command line handling.
 *
 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
 */
/* big objects in bss:
 * 00000020 b bl_count
 * 00000074 b base_length
 * 00000078 b base_dist
 * 00000078 b static_dtree
 * 0000009c b bl_tree
 * 000000f4 b dyn_dtree
 * 00000100 b length_code
 * 00000200 b dist_code
 * 0000023d b depth
 * 00000400 b flag_buf
 * 0000047a b heap
 * 00000480 b static_ltree
 * 000008f4 b dyn_ltree
 */
/* TODO: full support for -v for DESKTOP
 * "/usr/bin/gzip -v a bogus aa" should say:
a:       85.1% -- replaced with a.gz
gzip: bogus: No such file or directory
aa:      85.1% -- replaced with aa.gz
*/

//config:config GZIP
//config:	bool "gzip"
//config:	default y
//config:	help
//config:	  gzip is used to compress files.
//config:	  It's probably the most widely used UNIX compression program.
//config:
//config:config FEATURE_GZIP_LONG_OPTIONS
//config:	bool "Enable long options"
//config:	default y
//config:	depends on GZIP && LONG_OPTS
//config:	help
//config:	  Enable use of long options, increases size by about 106 Bytes
//config:
//config:config GZIP_FAST
//config:	int "Trade memory for gzip speed (0:small,slow - 2:fast,big)"
//config:	default 0
//config:	range 0 2
//config:	depends on GZIP
//config:	help
//config:	  Enable big memory options for gzip.
//config:	  0: small buffers, small hash-tables
//config:	  1: larger buffers, larger hash-tables
//config:	  2: larger buffers, largest hash-tables
//config:	  Larger models may give slightly better compression

//applet:IF_GZIP(APPLET(gzip, BB_DIR_BIN, BB_SUID_DROP))
//kbuild:lib-$(CONFIG_GZIP) += gzip.o

//usage:#define gzip_trivial_usage
//usage:       "[-cfd] [FILE]..."
//usage:#define gzip_full_usage "\n\n"
//usage:       "Compress FILEs (or stdin)\n"
//usage:     "\n	-d	Decompress"
//usage:     "\n	-c	Write to stdout"
//usage:     "\n	-f	Force"
//usage:
//usage:#define gzip_example_usage
//usage:       "$ ls -la /tmp/busybox*\n"
//usage:       "-rw-rw-r--    1 andersen andersen  1761280 Apr 14 17:47 /tmp/busybox.tar\n"
//usage:       "$ gzip /tmp/busybox.tar\n"
//usage:       "$ ls -la /tmp/busybox*\n"
//usage:       "-rw-rw-r--    1 andersen andersen   554058 Apr 14 17:49 /tmp/busybox.tar.gz\n"

#include "libbb.h"
#include "bb_archive.h"


/* ===========================================================================
 */
//#define DEBUG 1
/* Diagnostic functions */
#ifdef DEBUG
#  define Assert(cond,msg) { if (!(cond)) bb_error_msg(msg); }
#  define Trace(x) fprintf x
#  define Tracev(x) {if (verbose) fprintf x; }
#  define Tracevv(x) {if (verbose > 1) fprintf x; }
#  define Tracec(c,x) {if (verbose && (c)) fprintf x; }
#  define Tracecv(c,x) {if (verbose > 1 && (c)) fprintf x; }
#else
#  define Assert(cond,msg)
#  define Trace(x)
#  define Tracev(x)
#  define Tracevv(x)
#  define Tracec(c,x)
#  define Tracecv(c,x)
#endif


/* ===========================================================================
 */
#if   CONFIG_GZIP_FAST == 0
# define SMALL_MEM
#elif CONFIG_GZIP_FAST == 1
# define MEDIUM_MEM
#elif CONFIG_GZIP_FAST == 2
# define BIG_MEM
#else
# error "Invalid CONFIG_GZIP_FAST value"
#endif

#ifndef INBUFSIZ
#  ifdef SMALL_MEM
#    define INBUFSIZ  0x2000	/* input buffer size */
#  else
#    define INBUFSIZ  0x8000	/* input buffer size */
#  endif
#endif

#ifndef OUTBUFSIZ
#  ifdef SMALL_MEM
#    define OUTBUFSIZ   8192	/* output buffer size */
#  else
#    define OUTBUFSIZ  16384	/* output buffer size */
#  endif
#endif

#ifndef DIST_BUFSIZE
#  ifdef SMALL_MEM
#    define DIST_BUFSIZE 0x2000	/* buffer for distances, see trees.c */
#  else
#    define DIST_BUFSIZE 0x8000	/* buffer for distances, see trees.c */
#  endif
#endif

/* gzip flag byte */
#define ASCII_FLAG   0x01	/* bit 0 set: file probably ascii text */
#define CONTINUATION 0x02	/* bit 1 set: continuation of multi-part gzip file */
#define EXTRA_FIELD  0x04	/* bit 2 set: extra field present */
#define ORIG_NAME    0x08	/* bit 3 set: original file name present */
#define COMMENT      0x10	/* bit 4 set: file comment present */
#define RESERVED     0xC0	/* bit 6,7:   reserved */

/* internal file attribute */
#define UNKNOWN 0xffff
#define BINARY  0
#define ASCII   1

#ifndef WSIZE
#  define WSIZE 0x8000  /* window size--must be a power of two, and */
#endif                  /*  at least 32K for zip's deflate method */

#define MIN_MATCH  3
#define MAX_MATCH  258
/* The minimum and maximum match lengths */

#define MIN_LOOKAHEAD (MAX_MATCH+MIN_MATCH+1)
/* Minimum amount of lookahead, except at the end of the input file.
 * See deflate.c for comments about the MIN_MATCH+1.
 */

#define MAX_DIST  (WSIZE-MIN_LOOKAHEAD)
/* In order to simplify the code, particularly on 16 bit machines, match
 * distances are limited to MAX_DIST instead of WSIZE.
 */

#ifndef MAX_PATH_LEN
#  define MAX_PATH_LEN   1024	/* max pathname length */
#endif

#define seekable()    0	/* force sequential output */
#define translate_eol 0	/* no option -a yet */

#ifndef BITS
#  define BITS 16
#endif
#define INIT_BITS 9		/* Initial number of bits per code */

#define BIT_MASK    0x1f	/* Mask for 'number of compression bits' */
/* Mask 0x20 is reserved to mean a fourth header byte, and 0x40 is free.
 * It's a pity that old uncompress does not check bit 0x20. That makes
 * extension of the format actually undesirable because old compress
 * would just crash on the new format instead of giving a meaningful
 * error message. It does check the number of bits, but it's more
 * helpful to say "unsupported format, get a new version" than
 * "can only handle 16 bits".
 */

#ifdef MAX_EXT_CHARS
#  define MAX_SUFFIX  MAX_EXT_CHARS
#else
#  define MAX_SUFFIX  30
#endif


/* ===========================================================================
 * Compile with MEDIUM_MEM to reduce the memory requirements or
 * with SMALL_MEM to use as little memory as possible. Use BIG_MEM if the
 * entire input file can be held in memory (not possible on 16 bit systems).
 * Warning: defining these symbols affects HASH_BITS (see below) and thus
 * affects the compression ratio. The compressed output
 * is still correct, and might even be smaller in some cases.
 */

#ifdef SMALL_MEM
#   define HASH_BITS  13	/* Number of bits used to hash strings */
#endif
#ifdef MEDIUM_MEM
#   define HASH_BITS  14
#endif
#ifndef HASH_BITS
#   define HASH_BITS  15
   /* For portability to 16 bit machines, do not use values above 15. */
#endif

#define HASH_SIZE (unsigned)(1<<HASH_BITS)
#define HASH_MASK (HASH_SIZE-1)
#define WMASK     (WSIZE-1)
/* HASH_SIZE and WSIZE must be powers of two */
#ifndef TOO_FAR
#  define TOO_FAR 4096
#endif
/* Matches of length 3 are discarded if their distance exceeds TOO_FAR */


/* ===========================================================================
 * These types are not really 'char', 'short' and 'long'
 */
typedef uint8_t uch;
typedef uint16_t ush;
typedef uint32_t ulg;
typedef int32_t lng;

typedef ush Pos;
typedef unsigned IPos;
/* A Pos is an index in the character window. We use short instead of int to
 * save space in the various tables. IPos is used only for parameter passing.
 */

enum {
	WINDOW_SIZE = 2 * WSIZE,
/* window size, 2*WSIZE except for MMAP or BIG_MEM, where it is the
 * input file length plus MIN_LOOKAHEAD.
 */

	max_chain_length = 4096,
/* To speed up deflation, hash chains are never searched beyond this length.
 * A higher limit improves compression ratio but degrades the speed.
 */

	max_lazy_match = 258,
/* Attempt to find a better match only when the current match is strictly
 * smaller than this value. This mechanism is used only for compression
 * levels >= 4.
 */

	max_insert_length = max_lazy_match,
/* Insert new strings in the hash table only if the match length
 * is not greater than this length. This saves time but degrades compression.
 * max_insert_length is used only for compression levels <= 3.
 */

	good_match = 32,
/* Use a faster search when the previous match is longer than this */

/* Values for max_lazy_match, good_match and max_chain_length, depending on
 * the desired pack level (0..9). The values given below have been tuned to
 * exclude worst case performance for pathological files. Better values may be
 * found for specific files.
 */

	nice_match = 258,	/* Stop searching when current match exceeds this */
/* Note: the deflate() code requires max_lazy >= MIN_MATCH and max_chain >= 4
 * For deflate_fast() (levels <= 3) good is ignored and lazy has a different
 * meaning.
 */
};


struct globals {

	lng block_start;

/* window position at the beginning of the current output block. Gets
 * negative when the window is moved backwards.
 */
	unsigned ins_h;	/* hash index of string to be inserted */

#define H_SHIFT  ((HASH_BITS+MIN_MATCH-1) / MIN_MATCH)
/* Number of bits by which ins_h and del_h must be shifted at each
 * input step. It must be such that after MIN_MATCH steps, the oldest
 * byte no longer takes part in the hash key, that is:
 * H_SHIFT * MIN_MATCH >= HASH_BITS
 */

	unsigned prev_length;

/* Length of the best match at previous step. Matches not greater than this
 * are discarded. This is used in the lazy match evaluation.
 */

	unsigned strstart;	/* start of string to insert */
	unsigned match_start;	/* start of matching string */
	unsigned lookahead;	/* number of valid bytes ahead in window */

/* ===========================================================================
 */
#define DECLARE(type, array, size) \
	type * array
#define ALLOC(type, array, size) \
	array = xzalloc((size_t)(((size)+1L)/2) * 2*sizeof(type))
#define FREE(array) \
	do { free(array); array = NULL; } while (0)

	/* global buffers */

	/* buffer for literals or lengths */
	/* DECLARE(uch, l_buf, LIT_BUFSIZE); */
	DECLARE(uch, l_buf, INBUFSIZ);

	DECLARE(ush, d_buf, DIST_BUFSIZE);
	DECLARE(uch, outbuf, OUTBUFSIZ);

/* Sliding window. Input bytes are read into the second half of the window,
 * and move to the first half later to keep a dictionary of at least WSIZE
 * bytes. With this organization, matches are limited to a distance of
 * WSIZE-MAX_MATCH bytes, but this ensures that IO is always
 * performed with a length multiple of the block size. Also, it limits
 * the window size to 64K, which is quite useful on MSDOS.
 * To do: limit the window size to WSIZE+BSZ if SMALL_MEM (the code would
 * be less efficient).
 */
	DECLARE(uch, window, 2L * WSIZE);

/* Link to older string with same hash index. To limit the size of this
 * array to 64K, this link is maintained only for the last 32K strings.
 * An index in this array is thus a window index modulo 32K.
 */
	/* DECLARE(Pos, prev, WSIZE); */
	DECLARE(ush, prev, 1L << BITS);

/* Heads of the hash chains or 0. */
	/* DECLARE(Pos, head, 1<<HASH_BITS); */
#define head (G1.prev + WSIZE) /* hash head (see deflate.c) */

/* number of input bytes */
	ulg isize;		/* only 32 bits stored in .gz file */

/* bbox always use stdin/stdout */
#define ifd STDIN_FILENO	/* input file descriptor */
#define ofd STDOUT_FILENO	/* output file descriptor */

#ifdef DEBUG
	unsigned insize;	/* valid bytes in l_buf */
#endif
	unsigned outcnt;	/* bytes in output buffer */

	smallint eofile;	/* flag set at end of input file */

/* ===========================================================================
 * Local data used by the "bit string" routines.
 */

	unsigned short bi_buf;

/* Output buffer. bits are inserted starting at the bottom (least significant
 * bits).
 */

#undef BUF_SIZE
#define BUF_SIZE (8 * sizeof(G1.bi_buf))
/* Number of bits used within bi_buf. (bi_buf might be implemented on
 * more than 16 bits on some systems.)
 */

	int bi_valid;

/* Current input function. Set to mem_read for in-memory compression */

#ifdef DEBUG
	ulg bits_sent;			/* bit length of the compressed data */
#endif

	/*uint32_t *crc_32_tab;*/
	uint32_t crc;	/* shift register contents */
};

#define G1 (*(ptr_to_globals - 1))


/* ===========================================================================
 * Write the output buffer outbuf[0..outcnt-1] and update bytes_out.
 * (used for the compressed data only)
 */
static void flush_outbuf(void)
{
	if (G1.outcnt == 0)
		return;

	xwrite(ofd, (char *) G1.outbuf, G1.outcnt);
	G1.outcnt = 0;
}


/* ===========================================================================
 */
/* put_8bit is used for the compressed output */
#define put_8bit(c) \
do { \
	G1.outbuf[G1.outcnt++] = (c); \
	if (G1.outcnt == OUTBUFSIZ) \
		flush_outbuf(); \
} while (0)

/* Output a 16 bit value, lsb first */
static void put_16bit(ush w)
{
	/* GCC 4.2.1 won't optimize out redundant loads of G1.outcnt
	 * (probably because of fear of aliasing with G1.outbuf[]
	 * stores), do it explicitly:
	 */
	unsigned outcnt = G1.outcnt;
	uch *dst = &G1.outbuf[outcnt];

#if BB_UNALIGNED_MEMACCESS_OK && BB_LITTLE_ENDIAN
	if (outcnt < OUTBUFSIZ-2) {
		/* Common case */
		ush *dst16 = (void*) dst;
		*dst16 = w; /* unalinged LSB 16-bit store */
		G1.outcnt = outcnt + 2;
		return;
	}
	*dst = (uch)w;
	w >>= 8;
#else
	*dst = (uch)w;
	w >>= 8;
	if (outcnt < OUTBUFSIZ-2) {
		/* Common case */
		dst[1] = w;
		G1.outcnt = outcnt + 2;
		return;
	}
#endif

	/* Slowpath: we will need to do flush_outbuf() */
	G1.outcnt = ++outcnt;
	if (outcnt == OUTBUFSIZ)
		flush_outbuf();
	put_8bit(w);
}

static void put_32bit(ulg n)
{
	put_16bit(n);
	put_16bit(n >> 16);
}

/* ===========================================================================
 * Run a set of bytes through the crc shift register.  If s is a NULL
 * pointer, then initialize the crc shift register contents instead.
 * Return the current crc in either case.
 */
static void updcrc(uch * s, unsigned n)
{
	G1.crc = crc32_block_endian0(G1.crc, s, n, global_crc32_table /*G1.crc_32_tab*/);
}


/* ===========================================================================
 * Read a new buffer from the current input file, perform end-of-line
 * translation, and update the crc and input file size.
 * IN assertion: size >= 2 (for end-of-line translation)
 */
static unsigned file_read(void *buf, unsigned size)
{
	unsigned len;

	Assert(G1.insize == 0, "l_buf not empty");

	len = safe_read(ifd, buf, size);
	if (len == (unsigned)(-1) || len == 0)
		return len;

	updcrc(buf, len);
	G1.isize += len;
	return len;
}


/* ===========================================================================
 * Send a value on a given number of bits.
 * IN assertion: length <= 16 and value fits in length bits.
 */
static void send_bits(int value, int length)
{
#ifdef DEBUG
	Tracev((stderr, " l %2d v %4x ", length, value));
	Assert(length > 0 && length <= 15, "invalid length");
	G1.bits_sent += length;
#endif
	/* If not enough room in bi_buf, use (valid) bits from bi_buf and
	 * (16 - bi_valid) bits from value, leaving (width - (16-bi_valid))
	 * unused bits in value.
	 */
	if (G1.bi_valid > (int) BUF_SIZE - length) {
		G1.bi_buf |= (value << G1.bi_valid);
		put_16bit(G1.bi_buf);
		G1.bi_buf = (ush) value >> (BUF_SIZE - G1.bi_valid);
		G1.bi_valid += length - BUF_SIZE;
	} else {
		G1.bi_buf |= value << G1.bi_valid;
		G1.bi_valid += length;
	}
}


/* ===========================================================================
 * Reverse the first len bits of a code, using straightforward code (a faster
 * method would use a table)
 * IN assertion: 1 <= len <= 15
 */
static unsigned bi_reverse(unsigned code, int len)
{
	unsigned res = 0;

	while (1) {
		res |= code & 1;
		if (--len <= 0) return res;
		code >>= 1;
		res <<= 1;
	}
}


/* ===========================================================================
 * Write out any remaining bits in an incomplete byte.
 */
static void bi_windup(void)
{
	if (G1.bi_valid > 8) {
		put_16bit(G1.bi_buf);
	} else if (G1.bi_valid > 0) {
		put_8bit(G1.bi_buf);
	}
	G1.bi_buf = 0;
	G1.bi_valid = 0;
#ifdef DEBUG
	G1.bits_sent = (G1.bits_sent + 7) & ~7;
#endif
}


/* ===========================================================================
 * Copy a stored block to the zip file, storing first the length and its
 * one's complement if requested.
 */
static void copy_block(char *buf, unsigned len, int header)
{
	bi_windup();		/* align on byte boundary */

	if (header) {
		put_16bit(len);
		put_16bit(~len);
#ifdef DEBUG
		G1.bits_sent += 2 * 16;
#endif
	}
#ifdef DEBUG
	G1.bits_sent += (ulg) len << 3;
#endif
	while (len--) {
		put_8bit(*buf++);
	}
}


/* ===========================================================================
 * Fill the window when the lookahead becomes insufficient.
 * Updates strstart and lookahead, and sets eofile if end of input file.
 * IN assertion: lookahead < MIN_LOOKAHEAD && strstart + lookahead > 0
 * OUT assertions: at least one byte has been read, or eofile is set;
 *    file reads are performed for at least two bytes (required for the
 *    translate_eol option).
 */
static void fill_window(void)
{
	unsigned n, m;
	unsigned more =	WINDOW_SIZE - G1.lookahead - G1.strstart;
	/* Amount of free space at the end of the window. */

	/* If the window is almost full and there is insufficient lookahead,
	 * move the upper half to the lower one to make room in the upper half.
	 */
	if (more == (unsigned) -1) {
		/* Very unlikely, but possible on 16 bit machine if strstart == 0
		 * and lookahead == 1 (input done one byte at time)
		 */
		more--;
	} else if (G1.strstart >= WSIZE + MAX_DIST) {
		/* By the IN assertion, the window is not empty so we can't confuse
		 * more == 0 with more == 64K on a 16 bit machine.
		 */
		Assert(WINDOW_SIZE == 2 * WSIZE, "no sliding with BIG_MEM");

		memcpy(G1.window, G1.window + WSIZE, WSIZE);
		G1.match_start -= WSIZE;
		G1.strstart -= WSIZE;	/* we now have strstart >= MAX_DIST: */

		G1.block_start -= WSIZE;

		for (n = 0; n < HASH_SIZE; n++) {
			m = head[n];
			head[n] = (Pos) (m >= WSIZE ? m - WSIZE : 0);
		}
		for (n = 0; n < WSIZE; n++) {
			m = G1.prev[n];
			G1.prev[n] = (Pos) (m >= WSIZE ? m - WSIZE : 0);
			/* If n is not on any hash chain, prev[n] is garbage but
			 * its value will never be used.
			 */
		}
		more += WSIZE;
	}
	/* At this point, more >= 2 */
	if (!G1.eofile) {
		n = file_read(G1.window + G1.strstart + G1.lookahead, more);
		if (n == 0 || n == (unsigned) -1) {
			G1.eofile = 1;
		} else {
			G1.lookahead += n;
		}
	}
}


/* ===========================================================================
 * Set match_start to the longest match starting at the given string and
 * return its length. Matches shorter or equal to prev_length are discarded,
 * in which case the result is equal to prev_length and match_start is
 * garbage.
 * IN assertions: cur_match is the head of the hash chain for the current
 *   string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1
 */

/* For MSDOS, OS/2 and 386 Unix, an optimized version is in match.asm or
 * match.s. The code is functionally equivalent, so you can use the C version
 * if desired.
 */
static int longest_match(IPos cur_match)
{
	unsigned chain_length = max_chain_length;	/* max hash chain length */
	uch *scan = G1.window + G1.strstart;	/* current string */
	uch *match;	/* matched string */
	int len;	/* length of current match */
	int best_len = G1.prev_length;	/* best match length so far */
	IPos limit = G1.strstart > (IPos) MAX_DIST ? G1.strstart - (IPos) MAX_DIST : 0;
	/* Stop when cur_match becomes <= limit. To simplify the code,
	 * we prevent matches with the string of window index 0.
	 */

/* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
 * It is easy to get rid of this optimization if necessary.
 */
#if HASH_BITS < 8 || MAX_MATCH != 258
#  error Code too clever
#endif
	uch *strend = G1.window + G1.strstart + MAX_MATCH;
	uch scan_end1 = scan[best_len - 1];
	uch scan_end = scan[best_len];

	/* Do not waste too much time if we already have a good match: */
	if (G1.prev_length >= good_match) {
		chain_length >>= 2;
	}
	Assert(G1.strstart <= WINDOW_SIZE - MIN_LOOKAHEAD, "insufficient lookahead");

	do {
		Assert(cur_match < G1.strstart, "no future");
		match = G1.window + cur_match;

		/* Skip to next match if the match length cannot increase
		 * or if the match length is less than 2:
		 */
		if (match[best_len] != scan_end
		 || match[best_len - 1] != scan_end1
		 || *match != *scan || *++match != scan[1]
		) {
			continue;
		}

		/* The check at best_len-1 can be removed because it will be made
		 * again later. (This heuristic is not always a win.)
		 * It is not necessary to compare scan[2] and match[2] since they
		 * are always equal when the other bytes match, given that
		 * the hash keys are equal and that HASH_BITS >= 8.
		 */
		scan += 2, match++;

		/* We check for insufficient lookahead only every 8th comparison;
		 * the 256th check will be made at strstart+258.
		 */
		do {
		} while (*++scan == *++match && *++scan == *++match &&
				 *++scan == *++match && *++scan == *++match &&
				 *++scan == *++match && *++scan == *++match &&
				 *++scan == *++match && *++scan == *++match && scan < strend);

		len = MAX_MATCH - (int) (strend - scan);
		scan = strend - MAX_MATCH;

		if (len > best_len) {
			G1.match_start = cur_match;
			best_len = len;
			if (len >= nice_match)
				break;
			scan_end1 = scan[best_len - 1];
			scan_end = scan[best_len];
		}
	} while ((cur_match = G1.prev[cur_match & WMASK]) > limit
			 && --chain_length != 0);

	return best_len;
}


#ifdef DEBUG
/* ===========================================================================
 * Check that the match at match_start is indeed a match.
 */
static void check_match(IPos start, IPos match, int length)
{
	/* check that the match is indeed a match */
	if (memcmp(G1.window + match, G1.window + start, length) != 0) {
		bb_error_msg(" start %d, match %d, length %d", start, match, length);
		bb_error_msg("invalid match");
	}
	if (verbose > 1) {
		bb_error_msg("\\[%d,%d]", start - match, length);
		do {
			bb_putchar_stderr(G1.window[start++]);
		} while (--length != 0);
	}
}
#else
#  define check_match(start, match, length) ((void)0)
#endif


/* trees.c -- output deflated data using Huffman coding
 * Copyright (C) 1992-1993 Jean-loup Gailly
 * This is free software; you can redistribute it and/or modify it under the
 * terms of the GNU General Public License, see the file COPYING.
 */

/*  PURPOSE
 *      Encode various sets of source values using variable-length
 *      binary code trees.
 *
 *  DISCUSSION
 *      The PKZIP "deflation" process uses several Huffman trees. The more
 *      common source values are represented by shorter bit sequences.
 *
 *      Each code tree is stored in the ZIP file in a compressed form
 *      which is itself a Huffman encoding of the lengths of
 *      all the code strings (in ascending order by source values).
 *      The actual code strings are reconstructed from the lengths in
 *      the UNZIP process, as described in the "application note"
 *      (APPNOTE.TXT) distributed as part of PKWARE's PKZIP program.
 *
 *  REFERENCES
 *      Lynch, Thomas J.
 *          Data Compression:  Techniques and Applications, pp. 53-55.
 *          Lifetime Learning Publications, 1985.  ISBN 0-534-03418-7.
 *
 *      Storer, James A.
 *          Data Compression:  Methods and Theory, pp. 49-50.
 *          Computer Science Press, 1988.  ISBN 0-7167-8156-5.
 *
 *      Sedgewick, R.
 *          Algorithms, p290.
 *          Addison-Wesley, 1983. ISBN 0-201-06672-6.
 *
 *  INTERFACE
 *      void ct_init()
 *          Allocate the match buffer, initialize the various tables [and save
 *          the location of the internal file attribute (ascii/binary) and
 *          method (DEFLATE/STORE) -- deleted in bbox]
 *
 *      void ct_tally(int dist, int lc);
 *          Save the match info and tally the frequency counts.
 *
 *      ulg flush_block(char *buf, ulg stored_len, int eof)
 *          Determine the best encoding for the current block: dynamic trees,
 *          static trees or store, and output the encoded block to the zip
 *          file. Returns the total compressed length for the file so far.
 */

#define MAX_BITS 15
/* All codes must not exceed MAX_BITS bits */

#define MAX_BL_BITS 7
/* Bit length codes must not exceed MAX_BL_BITS bits */

#define LENGTH_CODES 29
/* number of length codes, not counting the special END_BLOCK code */

#define LITERALS  256
/* number of literal bytes 0..255 */

#define END_BLOCK 256
/* end of block literal code */

#define L_CODES (LITERALS+1+LENGTH_CODES)
/* number of Literal or Length codes, including the END_BLOCK code */

#define D_CODES   30
/* number of distance codes */

#define BL_CODES  19
/* number of codes used to transfer the bit lengths */

/* extra bits for each length code */
static const uint8_t extra_lbits[LENGTH_CODES] ALIGN1 = {
	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
};

/* extra bits for each distance code */
static const uint8_t extra_dbits[D_CODES] ALIGN1 = {
	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
};

/* extra bits for each bit length code */
static const uint8_t extra_blbits[BL_CODES] ALIGN1 = {
	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 3, 7 };

/* number of codes at each bit length for an optimal tree */
static const uint8_t bl_order[BL_CODES] ALIGN1 = {
	16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15 };

#define STORED_BLOCK 0
#define STATIC_TREES 1
#define DYN_TREES    2
/* The three kinds of block type */

#ifndef LIT_BUFSIZE
#  ifdef SMALL_MEM
#    define LIT_BUFSIZE  0x2000
#  else
#  ifdef MEDIUM_MEM
#    define LIT_BUFSIZE  0x4000
#  else
#    define LIT_BUFSIZE  0x8000
#  endif
#  endif
#endif
#ifndef DIST_BUFSIZE
#  define DIST_BUFSIZE  LIT_BUFSIZE
#endif
/* Sizes of match buffers for literals/lengths and distances.  There are
 * 4 reasons for limiting LIT_BUFSIZE to 64K:
 *   - frequencies can be kept in 16 bit counters
 *   - if compression is not successful for the first block, all input data is
 *     still in the window so we can still emit a stored block even when input
 *     comes from standard input.  (This can also be done for all blocks if
 *     LIT_BUFSIZE is not greater than 32K.)
 *   - if compression is not successful for a file smaller than 64K, we can
 *     even emit a stored file instead of a stored block (saving 5 bytes).
 *   - creating new Huffman trees less frequently may not provide fast
 *     adaptation to changes in the input data statistics. (Take for
 *     example a binary file with poorly compressible code followed by
 *     a highly compressible string table.) Smaller buffer sizes give
 *     fast adaptation but have of course the overhead of transmitting trees
 *     more frequently.
 *   - I can't count above 4
 * The current code is general and allows DIST_BUFSIZE < LIT_BUFSIZE (to save
 * memory at the expense of compression). Some optimizations would be possible
 * if we rely on DIST_BUFSIZE == LIT_BUFSIZE.
 */
#define REP_3_6      16
/* repeat previous bit length 3-6 times (2 bits of repeat count) */
#define REPZ_3_10    17
/* repeat a zero length 3-10 times  (3 bits of repeat count) */
#define REPZ_11_138  18
/* repeat a zero length 11-138 times  (7 bits of repeat count) */

/* ===========================================================================
*/
/* Data structure describing a single value and its code string. */
typedef struct ct_data {
	union {
		ush freq;		/* frequency count */
		ush code;		/* bit string */
	} fc;
	union {
		ush dad;		/* father node in Huffman tree */
		ush len;		/* length of bit string */
	} dl;
} ct_data;

#define Freq fc.freq
#define Code fc.code
#define Dad  dl.dad
#define Len  dl.len

#define HEAP_SIZE (2*L_CODES + 1)
/* maximum heap size */

typedef struct tree_desc {
	ct_data *dyn_tree;	/* the dynamic tree */
	ct_data *static_tree;	/* corresponding static tree or NULL */
	const uint8_t *extra_bits;	/* extra bits for each code or NULL */
	int extra_base;		/* base index for extra_bits */
	int elems;			/* max number of elements in the tree */
	int max_length;		/* max bit length for the codes */
	int max_code;		/* largest code with non zero frequency */
} tree_desc;

struct globals2 {

	ush heap[HEAP_SIZE];     /* heap used to build the Huffman trees */
	int heap_len;            /* number of elements in the heap */
	int heap_max;            /* element of largest frequency */

/* The sons of heap[n] are heap[2*n] and heap[2*n+1]. heap[0] is not used.
 * The same heap array is used to build all trees.
 */

	ct_data dyn_ltree[HEAP_SIZE];	/* literal and length tree */
	ct_data dyn_dtree[2 * D_CODES + 1];	/* distance tree */

	ct_data static_ltree[L_CODES + 2];

/* The static literal tree. Since the bit lengths are imposed, there is no
 * need for the L_CODES extra codes used during heap construction. However
 * The codes 286 and 287 are needed to build a canonical tree (see ct_init
 * below).
 */

	ct_data static_dtree[D_CODES];

/* The static distance tree. (Actually a trivial tree since all codes use
 * 5 bits.)
 */

	ct_data bl_tree[2 * BL_CODES + 1];

/* Huffman tree for the bit lengths */

	tree_desc l_desc;
	tree_desc d_desc;
	tree_desc bl_desc;

	ush bl_count[MAX_BITS + 1];

/* The lengths of the bit length codes are sent in order of decreasing
 * probability, to avoid transmitting the lengths for unused bit length codes.
 */

	uch depth[2 * L_CODES + 1];

/* Depth of each subtree used as tie breaker for trees of equal frequency */

	uch length_code[MAX_MATCH - MIN_MATCH + 1];

/* length code for each normalized match length (0 == MIN_MATCH) */

	uch dist_code[512];

/* distance codes. The first 256 values correspond to the distances
 * 3 .. 258, the last 256 values correspond to the top 8 bits of
 * the 15 bit distances.
 */

	int base_length[LENGTH_CODES];

/* First normalized length for each code (0 = MIN_MATCH) */

	int base_dist[D_CODES];

/* First normalized distance for each code (0 = distance of 1) */

	uch flag_buf[LIT_BUFSIZE / 8];

/* flag_buf is a bit array distinguishing literals from lengths in
 * l_buf, thus indicating the presence or absence of a distance.
 */

	unsigned last_lit;       /* running index in l_buf */
	unsigned last_dist;      /* running index in d_buf */
	unsigned last_flags;     /* running index in flag_buf */
	uch flags;               /* current flags not yet saved in flag_buf */
	uch flag_bit;            /* current bit used in flags */

/* bits are filled in flags starting at bit 0 (least significant).
 * Note: these flags are overkill in the current code since we don't
 * take advantage of DIST_BUFSIZE == LIT_BUFSIZE.
 */

	ulg opt_len;             /* bit length of current block with optimal trees */
	ulg static_len;          /* bit length of current block with static trees */

	ulg compressed_len;      /* total bit length of compressed file */
};

#define G2ptr ((struct globals2*)(ptr_to_globals))
#define G2 (*G2ptr)


/* ===========================================================================
 */
static void gen_codes(ct_data * tree, int max_code);
static void build_tree(tree_desc * desc);
static void scan_tree(ct_data * tree, int max_code);
static void send_tree(ct_data * tree, int max_code);
static int build_bl_tree(void);
static void send_all_trees(int lcodes, int dcodes, int blcodes);
static void compress_block(ct_data * ltree, ct_data * dtree);


#ifndef DEBUG
/* Send a code of the given tree. c and tree must not have side effects */
#  define SEND_CODE(c, tree) send_bits(tree[c].Code, tree[c].Len)
#else
#  define SEND_CODE(c, tree) \
{ \
	if (verbose > 1) bb_error_msg("\ncd %3d ", (c)); \
	send_bits(tree[c].Code, tree[c].Len); \
}
#endif

#define D_CODE(dist) \
	((dist) < 256 ? G2.dist_code[dist] : G2.dist_code[256 + ((dist)>>7)])
/* Mapping from a distance to a distance code. dist is the distance - 1 and
 * must not have side effects. dist_code[256] and dist_code[257] are never
 * used.
 * The arguments must not have side effects.
 */


/* ===========================================================================
 * Initialize a new block.
 */
static void init_block(void)
{
	int n; /* iterates over tree elements */

	/* Initialize the trees. */
	for (n = 0; n < L_CODES; n++)
		G2.dyn_ltree[n].Freq = 0;
	for (n = 0; n < D_CODES; n++)
		G2.dyn_dtree[n].Freq = 0;
	for (n = 0; n < BL_CODES; n++)
		G2.bl_tree[n].Freq = 0;

	G2.dyn_ltree[END_BLOCK].Freq = 1;
	G2.opt_len = G2.static_len = 0;
	G2.last_lit = G2.last_dist = G2.last_flags = 0;
	G2.flags = 0;
	G2.flag_bit = 1;
}


/* ===========================================================================
 * Restore the heap property by moving down the tree starting at node k,
 * exchanging a node with the smallest of its two sons if necessary, stopping
 * when the heap property is re-established (each father smaller than its
 * two sons).
 */

/* Compares to subtrees, using the tree depth as tie breaker when
 * the subtrees have equal frequency. This minimizes the worst case length. */
#define SMALLER(tree, n, m) \
	(tree[n].Freq < tree[m].Freq \
	|| (tree[n].Freq == tree[m].Freq && G2.depth[n] <= G2.depth[m]))

static void pqdownheap(ct_data * tree, int k)
{
	int v = G2.heap[k];
	int j = k << 1;		/* left son of k */

	while (j <= G2.heap_len) {
		/* Set j to the smallest of the two sons: */
		if (j < G2.heap_len && SMALLER(tree, G2.heap[j + 1], G2.heap[j]))
			j++;

		/* Exit if v is smaller than both sons */
		if (SMALLER(tree, v, G2.heap[j]))
			break;

		/* Exchange v with the smallest son */
		G2.heap[k] = G2.heap[j];
		k = j;

		/* And continue down the tree, setting j to the left son of k */
		j <<= 1;
	}
	G2.heap[k] = v;
}


/* ===========================================================================
 * Compute the optimal bit lengths for a tree and update the total bit length
 * for the current block.
 * IN assertion: the fields freq and dad are set, heap[heap_max] and
 *    above are the tree nodes sorted by increasing frequency.
 * OUT assertions: the field len is set to the optimal bit length, the
 *     array bl_count contains the frequencies for each bit length.
 *     The length opt_len is updated; static_len is also updated if stree is
 *     not null.
 */
static void gen_bitlen(tree_desc * desc)
{
	ct_data *tree = desc->dyn_tree;
	const uint8_t *extra = desc->extra_bits;
	int base = desc->extra_base;
	int max_code = desc->max_code;
	int max_length = desc->max_length;
	ct_data *stree = desc->static_tree;
	int h;				/* heap index */
	int n, m;			/* iterate over the tree elements */
	int bits;			/* bit length */
	int xbits;			/* extra bits */
	ush f;				/* frequency */
	int overflow = 0;	/* number of elements with bit length too large */

	for (bits = 0; bits <= MAX_BITS; bits++)
		G2.bl_count[bits] = 0;

	/* In a first pass, compute the optimal bit lengths (which may
	 * overflow in the case of the bit length tree).
	 */
	tree[G2.heap[G2.heap_max]].Len = 0;	/* root of the heap */

	for (h = G2.heap_max + 1; h < HEAP_SIZE; h++) {
		n = G2.heap[h];
		bits = tree[tree[n].Dad].Len + 1;
		if (bits > max_length) {
			bits = max_length;
			overflow++;
		}
		tree[n].Len = (ush) bits;
		/* We overwrite tree[n].Dad which is no longer needed */

		if (n > max_code)
			continue;	/* not a leaf node */

		G2.bl_count[bits]++;
		xbits = 0;
		if (n >= base)
			xbits = extra[n - base];
		f = tree[n].Freq;
		G2.opt_len += (ulg) f *(bits + xbits);

		if (stree)
			G2.static_len += (ulg) f * (stree[n].Len + xbits);
	}
	if (overflow == 0)
		return;

	Trace((stderr, "\nbit length overflow\n"));
	/* This happens for example on obj2 and pic of the Calgary corpus */

	/* Find the first bit length which could increase: */
	do {
		bits = max_length - 1;
		while (G2.bl_count[bits] == 0)
			bits--;
		G2.bl_count[bits]--;	/* move one leaf down the tree */
		G2.bl_count[bits + 1] += 2;	/* move one overflow item as its brother */
		G2.bl_count[max_length]--;
		/* The brother of the overflow item also moves one step up,
		 * but this does not affect bl_count[max_length]
		 */
		overflow -= 2;
	} while (overflow > 0);

	/* Now recompute all bit lengths, scanning in increasing frequency.
	 * h is still equal to HEAP_SIZE. (It is simpler to reconstruct all
	 * lengths instead of fixing only the wrong ones. This idea is taken
	 * from 'ar' written by Haruhiko Okumura.)
	 */
	for (bits = max_length; bits != 0; bits--) {
		n = G2.bl_count[bits];
		while (n != 0) {
			m = G2.heap[--h];
			if (m > max_code)
				continue;
			if (tree[m].Len != (unsigned) bits) {
				Trace((stderr, "code %d bits %d->%d\n", m, tree[m].Len, bits));
				G2.opt_len += ((int32_t) bits - tree[m].Len) * tree[m].Freq;
				tree[m].Len = bits;
			}
			n--;
		}
	}
}


/* ===========================================================================
 * Generate the codes for a given tree and bit counts (which need not be
 * optimal).
 * IN assertion: the array bl_count contains the bit length statistics for
 * the given tree and the field len is set for all tree elements.
 * OUT assertion: the field code is set for all tree elements of non
 *     zero code length.
 */
static void gen_codes(ct_data * tree, int max_code)
{
	ush next_code[MAX_BITS + 1];	/* next code value for each bit length */
	ush code = 0;		/* running code value */
	int bits;			/* bit index */
	int n;				/* code index */

	/* The distribution counts are first used to generate the code values
	 * without bit reversal.
	 */
	for (bits = 1; bits <= MAX_BITS; bits++) {
		next_code[bits] = code = (code + G2.bl_count[bits - 1]) << 1;
	}
	/* Check that the bit counts in bl_count are consistent. The last code
	 * must be all ones.
	 */
	Assert(code + G2.bl_count[MAX_BITS] - 1 == (1 << MAX_BITS) - 1,
			"inconsistent bit counts");
	Tracev((stderr, "\ngen_codes: max_code %d ", max_code));

	for (n = 0; n <= max_code; n++) {
		int len = tree[n].Len;

		if (len == 0)
			continue;
		/* Now reverse the bits */
		tree[n].Code = bi_reverse(next_code[len]++, len);

		Tracec(tree != G2.static_ltree,
			   (stderr, "\nn %3d %c l %2d c %4x (%x) ", n,
				(n > ' ' ? n : ' '), len, tree[n].Code,
				next_code[len] - 1));
	}
}


/* ===========================================================================
 * Construct one Huffman tree and assigns the code bit strings and lengths.
 * Update the total bit length for the current block.
 * IN assertion: the field freq is set for all tree elements.
 * OUT assertions: the fields len and code are set to the optimal bit length
 *     and corresponding code. The length opt_len is updated; static_len is
 *     also updated if stree is not null. The field max_code is set.
 */

/* Remove the smallest element from the heap and recreate the heap with
 * one less element. Updates heap and heap_len. */

#define SMALLEST 1
/* Index within the heap array of least frequent node in the Huffman tree */

#define PQREMOVE(tree, top) \
do { \
	top = G2.heap[SMALLEST]; \
	G2.heap[SMALLEST] = G2.heap[G2.heap_len--]; \
	pqdownheap(tree, SMALLEST); \
} while (0)

static void build_tree(tree_desc * desc)
{
	ct_data *tree = desc->dyn_tree;
	ct_data *stree = desc->static_tree;
	int elems = desc->elems;
	int n, m;			/* iterate over heap elements */
	int max_code = -1;	/* largest code with non zero frequency */
	int node = elems;	/* next internal node of the tree */

	/* Construct the initial heap, with least frequent element in
	 * heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1].
	 * heap[0] is not used.
	 */
	G2.heap_len = 0;
	G2.heap_max = HEAP_SIZE;

	for (n = 0; n < elems; n++) {
		if (tree[n].Freq != 0) {
			G2.heap[++G2.heap_len] = max_code = n;
			G2.depth[n] = 0;
		} else {
			tree[n].Len = 0;
		}
	}

	/* The pkzip format requires that at least one distance code exists,
	 * and that at least one bit should be sent even if there is only one
	 * possible code. So to avoid special checks later on we force at least
	 * two codes of non zero frequency.
	 */
	while (G2.heap_len < 2) {
		int new = G2.heap[++G2.heap_len] = (max_code < 2 ? ++max_code : 0);

		tree[new].Freq = 1;
		G2.depth[new] = 0;
		G2.opt_len--;
		if (stree)
			G2.static_len -= stree[new].Len;
		/* new is 0 or 1 so it does not have extra bits */
	}
	desc->max_code = max_code;

	/* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree,
	 * establish sub-heaps of increasing lengths:
	 */
	for (n = G2.heap_len / 2; n >= 1; n--)
		pqdownheap(tree, n);

	/* Construct the Huffman tree by repeatedly combining the least two
	 * frequent nodes.
	 */
	do {
		PQREMOVE(tree, n);	/* n = node of least frequency */
		m = G2.heap[SMALLEST];	/* m = node of next least frequency */

		G2.heap[--G2.heap_max] = n;	/* keep the nodes sorted by frequency */
		G2.heap[--G2.heap_max] = m;

		/* Create a new node father of n and m */
		tree[node].Freq = tree[n].Freq + tree[m].Freq;
		G2.depth[node] = MAX(G2.depth[n], G2.depth[m]) + 1;
		tree[n].Dad = tree[m].Dad = (ush) node;
#ifdef DUMP_BL_TREE
		if (tree == G2.bl_tree) {
			bb_error_msg("\nnode %d(%d), sons %d(%d) %d(%d)",
					node, tree[node].Freq, n, tree[n].Freq, m, tree[m].Freq);
		}
#endif
		/* and insert the new node in the heap */
		G2.heap[SMALLEST] = node++;
		pqdownheap(tree, SMALLEST);

	} while (G2.heap_len >= 2);

	G2.heap[--G2.heap_max] = G2.heap[SMALLEST];

	/* At this point, the fields freq and dad are set. We can now
	 * generate the bit lengths.
	 */
	gen_bitlen((tree_desc *) desc);

	/* The field len is now set, we can generate the bit codes */
	gen_codes((ct_data *) tree, max_code);
}


/* ===========================================================================
 * Scan a literal or distance tree to determine the frequencies of the codes
 * in the bit length tree. Updates opt_len to take into account the repeat
 * counts. (The contribution of the bit length codes will be added later
 * during the construction of bl_tree.)
 */
static void scan_tree(ct_data * tree, int max_code)
{
	int n;				/* iterates over all tree elements */
	int prevlen = -1;	/* last emitted length */
	int curlen;			/* length of current code */
	int nextlen = tree[0].Len;	/* length of next code */
	int count = 0;		/* repeat count of the current code */
	int max_count = 7;	/* max repeat count */
	int min_count = 4;	/* min repeat count */

	if (nextlen == 0) {
		max_count = 138;
		min_count = 3;
	}
	tree[max_code + 1].Len = 0xffff; /* guard */

	for (n = 0; n <= max_code; n++) {
		curlen = nextlen;
		nextlen = tree[n + 1].Len;
		if (++count < max_count && curlen == nextlen)
			continue;

		if (count < min_count) {
			G2.bl_tree[curlen].Freq += count;
		} else if (curlen != 0) {
			if (curlen != prevlen)
				G2.bl_tree[curlen].Freq++;
			G2.bl_tree[REP_3_6].Freq++;
		} else if (count <= 10) {
			G2.bl_tree[REPZ_3_10].Freq++;
		} else {
			G2.bl_tree[REPZ_11_138].Freq++;
		}
		count = 0;
		prevlen = curlen;

		max_count = 7;
		min_count = 4;
		if (nextlen == 0) {
			max_count = 138;
			min_count = 3;
		} else if (curlen == nextlen) {
			max_count = 6;
			min_count = 3;
		}
	}
}


/* ===========================================================================
 * Send a literal or distance tree in compressed form, using the codes in
 * bl_tree.
 */
static void send_tree(ct_data * tree, int max_code)
{
	int n;				/* iterates over all tree elements */
	int prevlen = -1;	/* last emitted length */
	int curlen;			/* length of current code */
	int nextlen = tree[0].Len;	/* length of next code */
	int count = 0;		/* repeat count of the current code */
	int max_count = 7;	/* max repeat count */
	int min_count = 4;	/* min repeat count */

/* tree[max_code+1].Len = -1; *//* guard already set */
	if (nextlen == 0)
		max_count = 138, min_count = 3;

	for (n = 0; n <= max_code; n++) {
		curlen = nextlen;
		nextlen = tree[n + 1].Len;
		if (++count < max_count && curlen == nextlen) {
			continue;
		} else if (count < min_count) {
			do {
				SEND_CODE(curlen, G2.bl_tree);
			} while (--count);
		} else if (curlen != 0) {
			if (curlen != prevlen) {
				SEND_CODE(curlen, G2.bl_tree);
				count--;
			}
			Assert(count >= 3 && count <= 6, " 3_6?");
			SEND_CODE(REP_3_6, G2.bl_tree);
			send_bits(count - 3, 2);
		} else if (count <= 10) {
			SEND_CODE(REPZ_3_10, G2.bl_tree);
			send_bits(count - 3, 3);
		} else {
			SEND_CODE(REPZ_11_138, G2.bl_tree);
			send_bits(count - 11, 7);
		}
		count = 0;
		prevlen = curlen;
		if (nextlen == 0) {
			max_count = 138;
			min_count = 3;
		} else if (curlen == nextlen) {
			max_count = 6;
			min_count = 3;
		} else {
			max_count = 7;
			min_count = 4;
		}
	}
}


/* ===========================================================================
 * Construct the Huffman tree for the bit lengths and return the index in
 * bl_order of the last bit length code to send.
 */
static int build_bl_tree(void)
{
	int max_blindex;	/* index of last bit length code of non zero freq */

	/* Determine the bit length frequencies for literal and distance trees */
	scan_tree(G2.dyn_ltree, G2.l_desc.max_code);
	scan_tree(G2.dyn_dtree, G2.d_desc.max_code);

	/* Build the bit length tree: */
	build_tree(&G2.bl_desc);
	/* opt_len now includes the length of the tree representations, except
	 * the lengths of the bit lengths codes and the 5+5+4 bits for the counts.
	 */

	/* Determine the number of bit length codes to send. The pkzip format
	 * requires that at least 4 bit length codes be sent. (appnote.txt says
	 * 3 but the actual value used is 4.)
	 */
	for (max_blindex = BL_CODES - 1; max_blindex >= 3; max_blindex--) {
		if (G2.bl_tree[bl_order[max_blindex]].Len != 0)
			break;
	}
	/* Update opt_len to include the bit length tree and counts */
	G2.opt_len += 3 * (max_blindex + 1) + 5 + 5 + 4;
	Tracev((stderr, "\ndyn trees: dyn %ld, stat %ld", G2.opt_len, G2.static_len));

	return max_blindex;
}


/* ===========================================================================
 * Send the header for a block using dynamic Huffman trees: the counts, the
 * lengths of the bit length codes, the literal tree and the distance tree.
 * IN assertion: lcodes >= 257, dcodes >= 1, blcodes >= 4.
 */
static void send_all_trees(int lcodes, int dcodes, int blcodes)
{
	int rank;			/* index in bl_order */

	Assert(lcodes >= 257 && dcodes >= 1 && blcodes >= 4, "not enough codes");
	Assert(lcodes <= L_CODES && dcodes <= D_CODES
		   && blcodes <= BL_CODES, "too many codes");
	Tracev((stderr, "\nbl counts: "));
	send_bits(lcodes - 257, 5);	/* not +255 as stated in appnote.txt */
	send_bits(dcodes - 1, 5);
	send_bits(blcodes - 4, 4);	/* not -3 as stated in appnote.txt */
	for (rank = 0; rank < blcodes; rank++) {
		Tracev((stderr, "\nbl code %2d ", bl_order[rank]));
		send_bits(G2.bl_tree[bl_order[rank]].Len, 3);
	}
	Tracev((stderr, "\nbl tree: sent %ld", G1.bits_sent));

	send_tree((ct_data *) G2.dyn_ltree, lcodes - 1);	/* send the literal tree */
	Tracev((stderr, "\nlit tree: sent %ld", G1.bits_sent));

	send_tree((ct_data *) G2.dyn_dtree, dcodes - 1);	/* send the distance tree */
	Tracev((stderr, "\ndist tree: sent %ld", G1.bits_sent));
}


/* ===========================================================================
 * Save the match info and tally the frequency counts. Return true if
 * the current block must be flushed.
 */
static int ct_tally(int dist, int lc)
{
	G1.l_buf[G2.last_lit++] = lc;
	if (dist == 0) {
		/* lc is the unmatched char */
		G2.dyn_ltree[lc].Freq++;
	} else {
		/* Here, lc is the match length - MIN_MATCH */
		dist--;			/* dist = match distance - 1 */
		Assert((ush) dist < (ush) MAX_DIST
		 && (ush) lc <= (ush) (MAX_MATCH - MIN_MATCH)
		 && (ush) D_CODE(dist) < (ush) D_CODES, "ct_tally: bad match"
		);

		G2.dyn_ltree[G2.length_code[lc] + LITERALS + 1].Freq++;
		G2.dyn_dtree[D_CODE(dist)].Freq++;

		G1.d_buf[G2.last_dist++] = dist;
		G2.flags |= G2.flag_bit;
	}
	G2.flag_bit <<= 1;

	/* Output the flags if they fill a byte: */
	if ((G2.last_lit & 7) == 0) {
		G2.flag_buf[G2.last_flags++] = G2.flags;
		G2.flags = 0;
		G2.flag_bit = 1;
	}
	/* Try to guess if it is profitable to stop the current block here */
	if ((G2.last_lit & 0xfff) == 0) {
		/* Compute an upper bound for the compressed length */
		ulg out_length = G2.last_lit * 8L;
		ulg in_length = (ulg) G1.strstart - G1.block_start;
		int dcode;

		for (dcode = 0; dcode < D_CODES; dcode++) {
			out_length += G2.dyn_dtree[dcode].Freq * (5L + extra_dbits[dcode]);
		}
		out_length >>= 3;
		Trace((stderr,
				"\nlast_lit %u, last_dist %u, in %ld, out ~%ld(%ld%%) ",
				G2.last_lit, G2.last_dist, in_length, out_length,
				100L - out_length * 100L / in_length));
		if (G2.last_dist < G2.last_lit / 2 && out_length < in_length / 2)
			return 1;
	}
	return (G2.last_lit == LIT_BUFSIZE - 1 || G2.last_dist == DIST_BUFSIZE);
	/* We avoid equality with LIT_BUFSIZE because of wraparound at 64K
	 * on 16 bit machines and because stored blocks are restricted to
	 * 64K-1 bytes.
	 */
}

/* ===========================================================================
 * Send the block data compressed using the given Huffman trees
 */
static void compress_block(ct_data * ltree, ct_data * dtree)
{
	unsigned dist;          /* distance of matched string */
	int lc;                 /* match length or unmatched char (if dist == 0) */
	unsigned lx = 0;        /* running index in l_buf */
	unsigned dx = 0;        /* running index in d_buf */
	unsigned fx = 0;        /* running index in flag_buf */
	uch flag = 0;           /* current flags */
	unsigned code;          /* the code to send */
	int extra;              /* number of extra bits to send */

	if (G2.last_lit != 0) do {
		if ((lx & 7) == 0)
			flag = G2.flag_buf[fx++];
		lc = G1.l_buf[lx++];
		if ((flag & 1) == 0) {
			SEND_CODE(lc, ltree);	/* send a literal byte */
			Tracecv(lc > ' ', (stderr, " '%c' ", lc));
		} else {
			/* Here, lc is the match length - MIN_MATCH */
			code = G2.length_code[lc];
			SEND_CODE(code + LITERALS + 1, ltree);	/* send the length code */
			extra = extra_lbits[code];
			if (extra != 0) {
				lc -= G2.base_length[code];
				send_bits(lc, extra);	/* send the extra length bits */
			}
			dist = G1.d_buf[dx++];
			/* Here, dist is the match distance - 1 */
			code = D_CODE(dist);
			Assert(code < D_CODES, "bad d_code");

			SEND_CODE(code, dtree);	/* send the distance code */
			extra = extra_dbits[code];
			if (extra != 0) {
				dist -= G2.base_dist[code];
				send_bits(dist, extra);	/* send the extra distance bits */
			}
		}			/* literal or match pair ? */
		flag >>= 1;
	} while (lx < G2.last_lit);

	SEND_CODE(END_BLOCK, ltree);
}


/* ===========================================================================
 * Determine the best encoding for the current block: dynamic trees, static
 * trees or store, and output the encoded block to the zip file. This function
 * returns the total compressed length for the file so far.
 */
static ulg flush_block(char *buf, ulg stored_len, int eof)
{
	ulg opt_lenb, static_lenb;      /* opt_len and static_len in bytes */
	int max_blindex;                /* index of last bit length code of non zero freq */

	G2.flag_buf[G2.last_flags] = G2.flags;   /* Save the flags for the last 8 items */

	/* Construct the literal and distance trees */
	build_tree(&G2.l_desc);
	Tracev((stderr, "\nlit data: dyn %ld, stat %ld", G2.opt_len, G2.static_len));

	build_tree(&G2.d_desc);
	Tracev((stderr, "\ndist data: dyn %ld, stat %ld", G2.opt_len, G2.static_len));
	/* At this point, opt_len and static_len are the total bit lengths of
	 * the compressed block data, excluding the tree representations.
	 */

	/* Build the bit length tree for the above two trees, and get the index
	 * in bl_order of the last bit length code to send.
	 */
	max_blindex = build_bl_tree();

	/* Determine the best encoding. Compute first the block length in bytes */
	opt_lenb = (G2.opt_len + 3 + 7) >> 3;
	static_lenb = (G2.static_len + 3 + 7) >> 3;

	Trace((stderr,
			"\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u dist %u ",
			opt_lenb, G2.opt_len, static_lenb, G2.static_len, stored_len,
			G2.last_lit, G2.last_dist));

	if (static_lenb <= opt_lenb)
		opt_lenb = static_lenb;

	/* If compression failed and this is the first and last block,
	 * and if the zip file can be seeked (to rewrite the local header),
	 * the whole file is transformed into a stored file:
	 */
	if (stored_len <= opt_lenb && eof && G2.compressed_len == 0L && seekable()) {
		/* Since LIT_BUFSIZE <= 2*WSIZE, the input data must be there: */
		if (buf == NULL)
			bb_error_msg("block vanished");

		copy_block(buf, (unsigned) stored_len, 0);	/* without header */
		G2.compressed_len = stored_len << 3;

	} else if (stored_len + 4 <= opt_lenb && buf != NULL) {
		/* 4: two words for the lengths */
		/* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE.
		 * Otherwise we can't have processed more than WSIZE input bytes since
		 * the last block flush, because compression would have been
		 * successful. If LIT_BUFSIZE <= WSIZE, it is never too late to
		 * transform a block into a stored block.
		 */
		send_bits((STORED_BLOCK << 1) + eof, 3);	/* send block type */
		G2.compressed_len = (G2.compressed_len + 3 + 7) & ~7L;
		G2.compressed_len += (stored_len + 4) << 3;

		copy_block(buf, (unsigned) stored_len, 1);	/* with header */

	} else if (static_lenb == opt_lenb) {
		send_bits((STATIC_TREES << 1) + eof, 3);
		compress_block((ct_data *) G2.static_ltree, (ct_data *) G2.static_dtree);
		G2.compressed_len += 3 + G2.static_len;
	} else {
		send_bits((DYN_TREES << 1) + eof, 3);
		send_all_trees(G2.l_desc.max_code + 1, G2.d_desc.max_code + 1,
					max_blindex + 1);
		compress_block((ct_data *) G2.dyn_ltree, (ct_data *) G2.dyn_dtree);
		G2.compressed_len += 3 + G2.opt_len;
	}
	Assert(G2.compressed_len == G1.bits_sent, "bad compressed size");
	init_block();

	if (eof) {
		bi_windup();
		G2.compressed_len += 7;	/* align on byte boundary */
	}
	Tracev((stderr, "\ncomprlen %lu(%lu) ", G2.compressed_len >> 3,
			G2.compressed_len - 7 * eof));

	return G2.compressed_len >> 3;
}


/* ===========================================================================
 * Update a hash value with the given input byte
 * IN  assertion: all calls to UPDATE_HASH are made with consecutive
 *    input characters, so that a running hash key can be computed from the
 *    previous key instead of complete recalculation each time.
 */
#define UPDATE_HASH(h, c) (h = (((h)<<H_SHIFT) ^ (c)) & HASH_MASK)


/* ===========================================================================
 * Same as above, but achieves better compression. We use a lazy
 * evaluation for matches: a match is finally adopted only if there is
 * no better match at the next window position.
 *
 * Processes a new input file and return its compressed length. Sets
 * the compressed length, crc, deflate flags and internal file
 * attributes.
 */

/* Flush the current block, with given end-of-file flag.
 * IN assertion: strstart is set to the end of the current match. */
#define FLUSH_BLOCK(eof) \
	flush_block( \
		G1.block_start >= 0L \
			? (char*)&G1.window[(unsigned)G1.block_start] \
			: (char*)NULL, \
		(ulg)G1.strstart - G1.block_start, \
		(eof) \
	)

/* Insert string s in the dictionary and set match_head to the previous head
 * of the hash chain (the most recent string with same hash key). Return
 * the previous length of the hash chain.
 * IN  assertion: all calls to INSERT_STRING are made with consecutive
 *    input characters and the first MIN_MATCH bytes of s are valid
 *    (except for the last MIN_MATCH-1 bytes of the input file). */
#define INSERT_STRING(s, match_head) \
do { \
	UPDATE_HASH(G1.ins_h, G1.window[(s) + MIN_MATCH-1]); \
	G1.prev[(s) & WMASK] = match_head = head[G1.ins_h]; \
	head[G1.ins_h] = (s); \
} while (0)

static ulg deflate(void)
{
	IPos hash_head;		/* head of hash chain */
	IPos prev_match;	/* previous match */
	int flush;			/* set if current block must be flushed */
	int match_available = 0;	/* set if previous match exists */
	unsigned match_length = MIN_MATCH - 1;	/* length of best match */

	/* Process the input block. */
	while (G1.lookahead != 0) {
		/* Insert the string window[strstart .. strstart+2] in the
		 * dictionary, and set hash_head to the head of the hash chain:
		 */
		INSERT_STRING(G1.strstart, hash_head);

		/* Find the longest match, discarding those <= prev_length.
		 */
		G1.prev_length = match_length;
		prev_match = G1.match_start;
		match_length = MIN_MATCH - 1;

		if (hash_head != 0 && G1.prev_length < max_lazy_match
		 && G1.strstart - hash_head <= MAX_DIST
		) {
			/* To simplify the code, we prevent matches with the string
			 * of window index 0 (in particular we have to avoid a match
			 * of the string with itself at the start of the input file).
			 */
			match_length = longest_match(hash_head);
			/* longest_match() sets match_start */
			if (match_length > G1.lookahead)
				match_length = G1.lookahead;

			/* Ignore a length 3 match if it is too distant: */
			if (match_length == MIN_MATCH && G1.strstart - G1.match_start > TOO_FAR) {
				/* If prev_match is also MIN_MATCH, G1.match_start is garbage
				 * but we will ignore the current match anyway.
				 */
				match_length--;
			}
		}
		/* If there was a match at the previous step and the current
		 * match is not better, output the previous match:
		 */
		if (G1.prev_length >= MIN_MATCH && match_length <= G1.prev_length) {
			check_match(G1.strstart - 1, prev_match, G1.prev_length);
			flush = ct_tally(G1.strstart - 1 - prev_match, G1.prev_length - MIN_MATCH);

			/* Insert in hash table all strings up to the end of the match.
			 * strstart-1 and strstart are already inserted.
			 */
			G1.lookahead -= G1.prev_length - 1;
			G1.prev_length -= 2;
			do {
				G1.strstart++;
				INSERT_STRING(G1.strstart, hash_head);
				/* strstart never exceeds WSIZE-MAX_MATCH, so there are
				 * always MIN_MATCH bytes ahead. If lookahead < MIN_MATCH
				 * these bytes are garbage, but it does not matter since the
				 * next lookahead bytes will always be emitted as literals.
				 */
			} while (--G1.prev_length != 0);
			match_available = 0;
			match_length = MIN_MATCH - 1;
			G1.strstart++;
			if (flush) {
				FLUSH_BLOCK(0);
				G1.block_start = G1.strstart;
			}
		} else if (match_available) {
			/* If there was no match at the previous position, output a
			 * single literal. If there was a match but the current match
			 * is longer, truncate the previous match to a single literal.
			 */
			Tracevv((stderr, "%c", G1.window[G1.strstart - 1]));
			if (ct_tally(0, G1.window[G1.strstart - 1])) {
				FLUSH_BLOCK(0);
				G1.block_start = G1.strstart;
			}
			G1.strstart++;
			G1.lookahead--;
		} else {
			/* There is no previous match to compare with, wait for
			 * the next step to decide.
			 */
			match_available = 1;
			G1.strstart++;
			G1.lookahead--;
		}
		Assert(G1.strstart <= G1.isize && lookahead <= G1.isize, "a bit too far");

		/* Make sure that we always have enough lookahead, except
		 * at the end of the input file. We need MAX_MATCH bytes
		 * for the next match, plus MIN_MATCH bytes to insert the
		 * string following the next match.
		 */
		while (G1.lookahead < MIN_LOOKAHEAD && !G1.eofile)
			fill_window();
	}
	if (match_available)
		ct_tally(0, G1.window[G1.strstart - 1]);

	return FLUSH_BLOCK(1);	/* eof */
}


/* ===========================================================================
 * Initialize the bit string routines.
 */
static void bi_init(void)
{
	G1.bi_buf = 0;
	G1.bi_valid = 0;
#ifdef DEBUG
	G1.bits_sent = 0L;
#endif
}


/* ===========================================================================
 * Initialize the "longest match" routines for a new file
 */
static void lm_init(ush * flagsp)
{
	unsigned j;

	/* Initialize the hash table. */
	memset(head, 0, HASH_SIZE * sizeof(*head));
	/* prev will be initialized on the fly */

	/* speed options for the general purpose bit flag */
	*flagsp |= 2;	/* FAST 4, SLOW 2 */
	/* ??? reduce max_chain_length for binary files */

	G1.strstart = 0;
	G1.block_start = 0L;

	G1.lookahead = file_read(G1.window,
			sizeof(int) <= 2 ? (unsigned) WSIZE : 2 * WSIZE);

	if (G1.lookahead == 0 || G1.lookahead == (unsigned) -1) {
		G1.eofile = 1;
		G1.lookahead = 0;
		return;
	}
	G1.eofile = 0;
	/* Make sure that we always have enough lookahead. This is important
	 * if input comes from a device such as a tty.
	 */
	while (G1.lookahead < MIN_LOOKAHEAD && !G1.eofile)
		fill_window();

	G1.ins_h = 0;
	for (j = 0; j < MIN_MATCH - 1; j++)
		UPDATE_HASH(G1.ins_h, G1.window[j]);
	/* If lookahead < MIN_MATCH, ins_h is garbage, but this is
	 * not important since only literal bytes will be emitted.
	 */
}


/* ===========================================================================
 * Allocate the match buffer, initialize the various tables and save the
 * location of the internal file attribute (ascii/binary) and method
 * (DEFLATE/STORE).
 * One callsite in zip()
 */
static void ct_init(void)
{
	int n;				/* iterates over tree elements */
	int length;			/* length value */
	int code;			/* code value */
	int dist;			/* distance index */

	G2.compressed_len = 0L;

#ifdef NOT_NEEDED
	if (G2.static_dtree[0].Len != 0)
		return;			/* ct_init already called */
#endif

	/* Initialize the mapping length (0..255) -> length code (0..28) */
	length = 0;
	for (code = 0; code < LENGTH_CODES - 1; code++) {
		G2.base_length[code] = length;
		for (n = 0; n < (1 << extra_lbits[code]); n++) {
			G2.length_code[length++] = code;
		}
	}
	Assert(length == 256, "ct_init: length != 256");
	/* Note that the length 255 (match length 258) can be represented
	 * in two different ways: code 284 + 5 bits or code 285, so we
	 * overwrite length_code[255] to use the best encoding:
	 */
	G2.length_code[length - 1] = code;

	/* Initialize the mapping dist (0..32K) -> dist code (0..29) */
	dist = 0;
	for (code = 0; code < 16; code++) {
		G2.base_dist[code] = dist;
		for (n = 0; n < (1 << extra_dbits[code]); n++) {
			G2.dist_code[dist++] = code;
		}
	}
	Assert(dist == 256, "ct_init: dist != 256");
	dist >>= 7;			/* from now on, all distances are divided by 128 */
	for (; code < D_CODES; code++) {
		G2.base_dist[code] = dist << 7;
		for (n = 0; n < (1 << (extra_dbits[code] - 7)); n++) {
			G2.dist_code[256 + dist++] = code;
		}
	}
	Assert(dist == 256, "ct_init: 256+dist != 512");

	/* Construct the codes of the static literal tree */
	/* already zeroed - it's in bss
	for (n = 0; n <= MAX_BITS; n++)
		G2.bl_count[n] = 0; */

	n = 0;
	while (n <= 143) {
		G2.static_ltree[n++].Len = 8;
		G2.bl_count[8]++;
	}
	while (n <= 255) {
		G2.static_ltree[n++].Len = 9;
		G2.bl_count[9]++;
	}
	while (n <= 279) {
		G2.static_ltree[n++].Len = 7;
		G2.bl_count[7]++;
	}
	while (n <= 287) {
		G2.static_ltree[n++].Len = 8;
		G2.bl_count[8]++;
	}
	/* Codes 286 and 287 do not exist, but we must include them in the
	 * tree construction to get a canonical Huffman tree (longest code
	 * all ones)
	 */
	gen_codes((ct_data *) G2.static_ltree, L_CODES + 1);

	/* The static distance tree is trivial: */
	for (n = 0; n < D_CODES; n++) {
		G2.static_dtree[n].Len = 5;
		G2.static_dtree[n].Code = bi_reverse(n, 5);
	}

	/* Initialize the first block of the first file: */
	init_block();
}


/* ===========================================================================
 * Deflate in to out.
 * IN assertions: the input and output buffers are cleared.
 */

static void zip(void)
{
	ush deflate_flags = 0;  /* pkzip -es, -en or -ex equivalent */

	G1.outcnt = 0;

	/* Write the header to the gzip file. See algorithm.doc for the format */
	/* magic header for gzip files: 1F 8B */
	/* compression method: 8 (DEFLATED) */
	/* general flags: 0 */
	put_32bit(0x00088b1f);
	put_32bit(0);		/* Unix timestamp */

	/* Write deflated file to zip file */
	G1.crc = ~0;

	bi_init();
	ct_init();
	lm_init(&deflate_flags);

	put_8bit(deflate_flags);	/* extra flags */
	put_8bit(3);	/* OS identifier = 3 (Unix) */

	deflate();

	/* Write the crc and uncompressed size */
	put_32bit(~G1.crc);
	put_32bit(G1.isize);

	flush_outbuf();
}


/* ======================================================================== */
static
IF_DESKTOP(long long) int FAST_FUNC pack_gzip(transformer_state_t *xstate UNUSED_PARAM)
{
	/* Clear input and output buffers */
	G1.outcnt = 0;
#ifdef DEBUG
	G1.insize = 0;
#endif
	G1.isize = 0;

	/* Reinit G2.xxx */
	memset(&G2, 0, sizeof(G2));
	G2.l_desc.dyn_tree     = G2.dyn_ltree;
	G2.l_desc.static_tree  = G2.static_ltree;
	G2.l_desc.extra_bits   = extra_lbits;
	G2.l_desc.extra_base   = LITERALS + 1;
	G2.l_desc.elems        = L_CODES;
	G2.l_desc.max_length   = MAX_BITS;
	//G2.l_desc.max_code     = 0;
	G2.d_desc.dyn_tree     = G2.dyn_dtree;
	G2.d_desc.static_tree  = G2.static_dtree;
	G2.d_desc.extra_bits   = extra_dbits;
	//G2.d_desc.extra_base   = 0;
	G2.d_desc.elems        = D_CODES;
	G2.d_desc.max_length   = MAX_BITS;
	//G2.d_desc.max_code     = 0;
	G2.bl_desc.dyn_tree    = G2.bl_tree;
	//G2.bl_desc.static_tree = NULL;
	G2.bl_desc.extra_bits  = extra_blbits,
	//G2.bl_desc.extra_base  = 0;
	G2.bl_desc.elems       = BL_CODES;
	G2.bl_desc.max_length  = MAX_BL_BITS;
	//G2.bl_desc.max_code    = 0;

#if 0
	/* Saving of timestamp is disabled. Why?
	 * - it is not Y2038-safe.
	 * - some people want deterministic results
	 *   (normally they'd use -n, but our -n is a nop).
	 * - it's bloat.
	 * Per RFC 1952, gzfile.time=0 is "no timestamp".
	 * If users will demand this to be reinstated,
	 * implement -n "don't save timestamp".
	 */
	struct stat s;
	s.st_ctime = 0;
	fstat(STDIN_FILENO, &s);
	zip(s.st_ctime);
#else
	zip();
#endif
	return 0;
}

#if ENABLE_FEATURE_GZIP_LONG_OPTIONS
static const char gzip_longopts[] ALIGN1 =
	"stdout\0"              No_argument       "c"
	"to-stdout\0"           No_argument       "c"
	"force\0"               No_argument       "f"
	"verbose\0"             No_argument       "v"
#if ENABLE_GUNZIP
	"decompress\0"          No_argument       "d"
	"uncompress\0"          No_argument       "d"
	"test\0"                No_argument       "t"
#endif
	"quiet\0"               No_argument       "q"
	"fast\0"                No_argument       "1"
	"best\0"                No_argument       "9"
	;
#endif

/*
 * Linux kernel build uses gzip -d -n. We accept and ignore -n.
 * Man page says:
 * -n --no-name
 * gzip: do not save the original file name and time stamp.
 * (The original name is always saved if the name had to be truncated.)
 * gunzip: do not restore the original file name/time even if present
 * (remove only the gzip suffix from the compressed file name).
 * This option is the default when decompressing.
 * -N --name
 * gzip: always save the original file name and time stamp (this is the default)
 * gunzip: restore the original file name and time stamp if present.
 */

int gzip_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
#if ENABLE_GUNZIP
int gzip_main(int argc, char **argv)
#else
int gzip_main(int argc UNUSED_PARAM, char **argv)
#endif
{
	unsigned opt;

#if ENABLE_FEATURE_GZIP_LONG_OPTIONS
	applet_long_options = gzip_longopts;
#endif
	/* Must match bbunzip's constants OPT_STDOUT, OPT_FORCE! */
	opt = getopt32(argv, "cfv" IF_GUNZIP("dt") "q123456789n");
#if ENABLE_GUNZIP /* gunzip_main may not be visible... */
	if (opt & 0x18) // -d and/or -t
		return gunzip_main(argc, argv);
#endif
	option_mask32 &= 0x7; /* ignore -q, -0..9 */
	//if (opt & 0x1) // -c
	//if (opt & 0x2) // -f
	//if (opt & 0x4) // -v
	argv += optind;

	SET_PTR_TO_GLOBALS((char *)xzalloc(sizeof(struct globals)+sizeof(struct globals2))
			+ sizeof(struct globals));

	/* Allocate all global buffers (for DYN_ALLOC option) */
	ALLOC(uch, G1.l_buf, INBUFSIZ);
	ALLOC(uch, G1.outbuf, OUTBUFSIZ);
	ALLOC(ush, G1.d_buf, DIST_BUFSIZE);
	ALLOC(uch, G1.window, 2L * WSIZE);
	ALLOC(ush, G1.prev, 1L << BITS);

	/* Initialize the CRC32 table */
	global_crc32_table = crc32_filltable(NULL, 0);

	return bbunpack(argv, pack_gzip, append_ext, "gz");
}