summaryrefslogtreecommitdiff
path: root/src/fontloader/misc/fontloader-font-otr.lua
blob: 2b18c1e0e8731ad3fb0ead8568cc02bc9d079a47 (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
if not modules then modules = { } end modules ['font-otr'] = {
    version   = 1.001,
    comment   = "companion to font-ini.mkiv",
    author    = "Hans Hagen, PRAGMA-ADE, Hasselt NL",
    copyright = "PRAGMA ADE / ConTeXt Development Team",
    license   = "see context related readme files"
}

-- When looking into a cid font relates issue in the ff library I wondered if
-- it made sense to use Lua to filter the information from the otf and ttf
-- files. Quite some ff code relates to special fonts and in practice we only
-- use rather normal opentype fonts.
--
-- The code here is based on the documentation (and examples) at the microsoft
-- website. The code will be extended and improved stepwise. After some experiments
-- I decided to convert to a format more suitable for the context font handler
-- because it makes no sense to rehash all those lookups again.
--
-- Currently we can use this code for getting basic info about the font, loading
-- shapes and loading the extensive table. I'm not sure if I will provide a ff
-- compatible output as well (We're not that far from it as currently I can load
-- all data reasonable fast.)

-- We can omit redundant glyphs names i.e. ones that match the agl or
-- are just a unicode string but it doesn't save that much. It will be an option
-- some day.

-- Optimizing the widths wil be done anyway as it save quite some on a cjk font
-- and the existing (old) code if okay.

-- todo: more messages (only if really needed)
--
-- considered, in math:
--
-- start -> first (so we can skip the first same-size one)
-- end   -> last
--
-- Widths and weights are kind of messy: for instance lmmonolt has a pfmweight of
-- 400 while it should be 300. So, for now we mostly stick to the old compromis.

-- We don't really need all those language tables so they might be dropped some
-- day.

-- The new reader is faster on some aspects and slower on other. The memory footprint
-- is lower. The string reader is a  bit faster than the file reader. The new reader
-- gives more efficient tables and has bit more analysis. In practice these times are
-- not that relevant because we cache. The otf files take a it more time because we
-- need to calculate the boundingboxes. In theory the processing of text should be
-- somewhat faster especially for complex fonts with many lookups.
--
--                        old    new    str reader
-- lmroman12-regular.otf  0.103  0.203  0.195
-- latinmodern-math.otf   0.454  0.768  0.712
-- husayni.ttf            1.142  1.526  1.259
--
-- If there is demand I will consider making a ff compatible table dumper but it's
-- probably more fun to provide a way to show features applied.

-- I experimented a bit with f:readbyte(n) and f:readshort() and so and it is indeed
-- faster but it might not be the real bottleneck as we still need to juggle data. It
-- is probably more memory efficient as no intermediate strings are involved.

-- if not characters then
--     require("char-def")
--     require("char-ini")
-- end

local next, type, unpack = next, type, unpack
local byte, lower, char, strip, gsub = string.byte, string.lower, string.char, string.strip, string.gsub
local bittest = bit32.btest
local concat, remove, unpack, fastcopy = table.concat, table.remov, table.unpack, table.fastcopy
local floor, abs, sqrt, round = math.floor, math.abs, math.sqrt, math.round
local P, R, S, C, Cs, Cc, Ct, Carg, Cmt = lpeg.P, lpeg.R, lpeg.S, lpeg.C, lpeg.Cs, lpeg.Cc, lpeg.Ct, lpeg.Carg, lpeg.Cmt
local lpegmatch = lpeg.match

local setmetatableindex = table.setmetatableindex
local formatters        = string.formatters
local sortedkeys        = table.sortedkeys
local sortedhash        = table.sortedhash
local stripstring       = string.strip
local utf16_to_utf8_be  = utf.utf16_to_utf8_be

local report            = logs.reporter("otf reader")

local trace_cmap        = false -- only for checking issues

fonts                   = fonts or { }
local handlers          = fonts.handlers or { }
fonts.handlers          = handlers
local otf               = handlers.otf or { }
handlers.otf            = otf
local readers           = otf.readers or { }
otf.readers             = readers

----- streamreader      = utilities.streams -- faster on big files
local streamreader      = utilities.files   -- faster on identify
local streamwriter      = utilities.files

readers.streamreader    = streamreader
readers.streamwriter    = streamwriter

local openfile          = streamreader.open
local closefile         = streamreader.close
----- skipbytes         = streamreader.skip
local setposition       = streamreader.setposition
local skipshort         = streamreader.skipshort
local readbytes         = streamreader.readbytes
local readstring        = streamreader.readstring
local readbyte          = streamreader.readcardinal1  --  8-bit unsigned integer
local readushort        = streamreader.readcardinal2  -- 16-bit unsigned integer
local readuint          = streamreader.readcardinal3  -- 24-bit unsigned integer
local readulong         = streamreader.readcardinal4  -- 24-bit unsigned integer
----- readchar          = streamreader.readinteger1   --  8-bit   signed integer
local readshort         = streamreader.readinteger2   -- 16-bit   signed integer
local readlong          = streamreader.readinteger4   -- 24-bit unsigned integer
local readfixed         = streamreader.readfixed4
local readfword         = readshort                   -- 16-bit   signed integer that describes a quantity in FUnits
local readufword        = readushort                  -- 16-bit unsigned integer that describes a quantity in FUnits
local readoffset        = readushort
local read2dot14        = streamreader.read2dot14     -- 16-bit signed fixed number with the low 14 bits of fraction (2.14) (F2DOT14)

function streamreader.readtag(f)
    return lower(strip(readstring(f,4)))
end

-- date represented in number of seconds since 12:00 midnight, January 1, 1904. The value is represented as a
-- signed 64-bit integer

local function readlongdatetime(f)
    local a, b, c, d, e, f, g, h = readbytes(f,8)
    return 0x100000000 * d + 0x1000000 * e + 0x10000 * f + 0x100 * g + h
end

local tableversion    = 0.004
readers.tableversion  = tableversion
local privateoffset   = fonts.constructors and fonts.constructors.privateoffset or 0xF0000 -- 0x10FFFF
local reportedskipped = { }


local function reportskippedtable(tag)
    if not reportedskipped[tag] then
        report("loading of table %a skipped (reported once only)",tag)
        reportedskipped[tag] = true
    end
end

-- We have quite some data tables. We are somewhat ff compatible with names but as I used
-- the information from the microsoft site there can be differences. Eventually I might end
-- up with a different ordering and naming.

local reservednames = { [0] =
    "copyright",
    "family",
    "subfamily",
    "uniqueid",
    "fullname",
    "version",
    "postscriptname",
    "trademark",
    "manufacturer",
    "designer",
    "description", -- descriptor in ff
    "vendorurl",
    "designerurl",
    "license",
    "licenseurl",
    "reserved",
    "typographicfamily",    -- preffamilyname
    "typographicsubfamily", -- prefmodifiers
    "compatiblefullname",   -- for mac
    "sampletext",
    "cidfindfontname",
    "wwsfamily",
    "wwssubfamily",
    "lightbackgroundpalette",
    "darkbackgroundpalette",
}

-- more at: https://www.microsoft.com/typography/otspec/name.htm

-- setmetatableindex(reservednames,function(t,k)
--     local v = "name_" .. k
--     t[k] =  v
--     return v
-- end)

local platforms = { [0] =
    "unicode",
    "macintosh",
    "iso",
    "windows",
    "custom",
}

local encodings = {
    -- these stay:
    unicode = { [0] =
        "unicode 1.0 semantics",
        "unicode 1.1 semantics",
        "iso/iec 10646",
        "unicode 2.0 bmp",             -- cmap subtable formats 0, 4, 6
        "unicode 2.0 full",            -- cmap subtable formats 0, 4, 6, 10, 12
        "unicode variation sequences", -- cmap subtable format 14).
        "unicode full repertoire",     -- cmap subtable formats 0, 4, 6, 10, 12, 13
    },
    -- these can go:
    macintosh = { [0] =
        "roman", "japanese", "chinese (traditional)", "korean", "arabic", "hebrew", "greek", "russian",
        "rsymbol", "devanagari", "gurmukhi", "gujarati", "oriya", "bengali", "tamil", "telugu", "kannada",
        "malayalam", "sinhalese", "burmese", "khmer", "thai", "laotian", "georgian", "armenian",
        "chinese (simplified)", "tibetan", "mongolian", "geez", "slavic", "vietnamese", "sindhi",
        "uninterpreted",
    },
    -- these stay:
    iso = { [0] =
        "7-bit ascii",
        "iso 10646",
        "iso 8859-1",
    },
    -- these stay:
    windows = { [0] =
        "symbol",
        "unicode bmp", -- this is utf16
        "shiftjis",
        "prc",
        "big5",
        "wansung",
        "johab",
        "reserved 7",
        "reserved 8",
        "reserved 9",
        "unicode ucs-4",
    },
    custom = {
        --custom: 0-255 : otf windows nt compatibility mapping
    }
}

local decoders = {
    unicode   = { },
    macintosh = { },
    iso       = { },
    windows   = {
        -- maybe always utf16
        ["unicode semantics"]           = utf16_to_utf8_be,
        ["unicode bmp"]                 = utf16_to_utf8_be,
        ["unicode full"]                = utf16_to_utf8_be,
        ["unicode 1.0 semantics"]       = utf16_to_utf8_be,
        ["unicode 1.1 semantics"]       = utf16_to_utf8_be,
        ["unicode 2.0 bmp"]             = utf16_to_utf8_be,
        ["unicode 2.0 full"]            = utf16_to_utf8_be,
        ["unicode variation sequences"] = utf16_to_utf8_be,
        ["unicode full repertoire"]     = utf16_to_utf8_be,
    },
    custom    = { },
}

-- This is bit over the top as we can just look for either windows, unicode or macintosh
-- names (in that order). A font with no english name is probably a weird one anyway.

local languages = {
    -- these stay:
    unicode = {
        [  0] = "english",
    },
    -- english can stay:
    macintosh = {
        [  0] = "english",
     -- [  1] = "french",
     -- [  2] = "german",
     -- [  3] = "italian",
     -- [  4] = "dutch",
     -- [  5] = "swedish",
     -- [  6] = "spanish",
     -- [  7] = "danish",
     -- [  8] = "portuguese",
     -- [  9] = "norwegian",
     -- [ 10] = "hebrew",
     -- [ 11] = "japanese",
     -- [ 12] = "arabic",
     -- [ 13] = "finnish",
     -- [ 14] = "greek",
     -- [ 15] = "icelandic",
     -- [ 16] = "maltese",
     -- [ 17] = "turkish",
     -- [ 18] = "croatian",
     -- [ 19] = "chinese (traditional)",
     -- [ 20] = "urdu",
     -- [ 21] = "hindi",
     -- [ 22] = "thai",
     -- [ 23] = "korean",
     -- [ 24] = "lithuanian",
     -- [ 25] = "polish",
     -- [ 26] = "hungarian",
     -- [ 27] = "estonian",
     -- [ 28] = "latvian",
     -- [ 29] = "sami",
     -- [ 30] = "faroese",
     -- [ 31] = "farsi/persian",
     -- [ 32] = "russian",
     -- [ 33] = "chinese (simplified)",
     -- [ 34] = "flemish",
     -- [ 35] = "irish gaelic",
     -- [ 36] = "albanian",
     -- [ 37] = "romanian",
     -- [ 38] = "czech",
     -- [ 39] = "slovak",
     -- [ 40] = "slovenian",
     -- [ 41] = "yiddish",
     -- [ 42] = "serbian",
     -- [ 43] = "macedonian",
     -- [ 44] = "bulgarian",
     -- [ 45] = "ukrainian",
     -- [ 46] = "byelorussian",
     -- [ 47] = "uzbek",
     -- [ 48] = "kazakh",
     -- [ 49] = "azerbaijani (cyrillic script)",
     -- [ 50] = "azerbaijani (arabic script)",
     -- [ 51] = "armenian",
     -- [ 52] = "georgian",
     -- [ 53] = "moldavian",
     -- [ 54] = "kirghiz",
     -- [ 55] = "tajiki",
     -- [ 56] = "turkmen",
     -- [ 57] = "mongolian (mongolian script)",
     -- [ 58] = "mongolian (cyrillic script)",
     -- [ 59] = "pashto",
     -- [ 60] = "kurdish",
     -- [ 61] = "kashmiri",
     -- [ 62] = "sindhi",
     -- [ 63] = "tibetan",
     -- [ 64] = "nepali",
     -- [ 65] = "sanskrit",
     -- [ 66] = "marathi",
     -- [ 67] = "bengali",
     -- [ 68] = "assamese",
     -- [ 69] = "gujarati",
     -- [ 70] = "punjabi",
     -- [ 71] = "oriya",
     -- [ 72] = "malayalam",
     -- [ 73] = "kannada",
     -- [ 74] = "tamil",
     -- [ 75] = "telugu",
     -- [ 76] = "sinhalese",
     -- [ 77] = "burmese",
     -- [ 78] = "khmer",
     -- [ 79] = "lao",
     -- [ 80] = "vietnamese",
     -- [ 81] = "indonesian",
     -- [ 82] = "tagalong",
     -- [ 83] = "malay (roman script)",
     -- [ 84] = "malay (arabic script)",
     -- [ 85] = "amharic",
     -- [ 86] = "tigrinya",
     -- [ 87] = "galla",
     -- [ 88] = "somali",
     -- [ 89] = "swahili",
     -- [ 90] = "kinyarwanda/ruanda",
     -- [ 91] = "rundi",
     -- [ 92] = "nyanja/chewa",
     -- [ 93] = "malagasy",
     -- [ 94] = "esperanto",
     -- [128] = "welsh",
     -- [129] = "basque",
     -- [130] = "catalan",
     -- [131] = "latin",
     -- [132] = "quenchua",
     -- [133] = "guarani",
     -- [134] = "aymara",
     -- [135] = "tatar",
     -- [136] = "uighur",
     -- [137] = "dzongkha",
     -- [138] = "javanese (roman script)",
     -- [139] = "sundanese (roman script)",
     -- [140] = "galician",
     -- [141] = "afrikaans",
     -- [142] = "breton",
     -- [143] = "inuktitut",
     -- [144] = "scottish gaelic",
     -- [145] = "manx gaelic",
     -- [146] = "irish gaelic (with dot above)",
     -- [147] = "tongan",
     -- [148] = "greek (polytonic)",
     -- [149] = "greenlandic",
     -- [150] = "azerbaijani (roman script)",
    },
    -- these can stay:
    iso = {
    },
    -- english can stay:
    windows = {
     -- [0x0436] = "afrikaans - south africa",
     -- [0x041c] = "albanian - albania",
     -- [0x0484] = "alsatian - france",
     -- [0x045e] = "amharic - ethiopia",
     -- [0x1401] = "arabic - algeria",
     -- [0x3c01] = "arabic - bahrain",
     -- [0x0c01] = "arabic - egypt",
     -- [0x0801] = "arabic - iraq",
     -- [0x2c01] = "arabic - jordan",
     -- [0x3401] = "arabic - kuwait",
     -- [0x3001] = "arabic - lebanon",
     -- [0x1001] = "arabic - libya",
     -- [0x1801] = "arabic - morocco",
     -- [0x2001] = "arabic - oman",
     -- [0x4001] = "arabic - qatar",
     -- [0x0401] = "arabic - saudi arabia",
     -- [0x2801] = "arabic - syria",
     -- [0x1c01] = "arabic - tunisia",
     -- [0x3801] = "arabic - u.a.e.",
     -- [0x2401] = "arabic - yemen",
     -- [0x042b] = "armenian - armenia",
     -- [0x044d] = "assamese - india",
     -- [0x082c] = "azeri (cyrillic) - azerbaijan",
     -- [0x042c] = "azeri (latin) - azerbaijan",
     -- [0x046d] = "bashkir - russia",
     -- [0x042d] = "basque - basque",
     -- [0x0423] = "belarusian - belarus",
     -- [0x0845] = "bengali - bangladesh",
     -- [0x0445] = "bengali - india",
     -- [0x201a] = "bosnian (cyrillic) - bosnia and herzegovina",
     -- [0x141a] = "bosnian (latin) - bosnia and herzegovina",
     -- [0x047e] = "breton - france",
     -- [0x0402] = "bulgarian - bulgaria",
     -- [0x0403] = "catalan - catalan",
     -- [0x0c04] = "chinese - hong kong s.a.r.",
     -- [0x1404] = "chinese - macao s.a.r.",
     -- [0x0804] = "chinese - people's republic of china",
     -- [0x1004] = "chinese - singapore",
     -- [0x0404] = "chinese - taiwan",
     -- [0x0483] = "corsican - france",
     -- [0x041a] = "croatian - croatia",
     -- [0x101a] = "croatian (latin) - bosnia and herzegovina",
     -- [0x0405] = "czech - czech republic",
     -- [0x0406] = "danish - denmark",
     -- [0x048c] = "dari - afghanistan",
     -- [0x0465] = "divehi - maldives",
     -- [0x0813] = "dutch - belgium",
     -- [0x0413] = "dutch - netherlands",
     -- [0x0c09] = "english - australia",
     -- [0x2809] = "english - belize",
     -- [0x1009] = "english - canada",
     -- [0x2409] = "english - caribbean",
     -- [0x4009] = "english - india",
     -- [0x1809] = "english - ireland",
     -- [0x2009] = "english - jamaica",
     -- [0x4409] = "english - malaysia",
     -- [0x1409] = "english - new zealand",
     -- [0x3409] = "english - republic of the philippines",
     -- [0x4809] = "english - singapore",
     -- [0x1c09] = "english - south africa",
     -- [0x2c09] = "english - trinidad and tobago",
     -- [0x0809] = "english - united kingdom",
        [0x0409] = "english - united states",
     -- [0x3009] = "english - zimbabwe",
     -- [0x0425] = "estonian - estonia",
     -- [0x0438] = "faroese - faroe islands",
     -- [0x0464] = "filipino - philippines",
     -- [0x040b] = "finnish - finland",
     -- [0x080c] = "french - belgium",
     -- [0x0c0c] = "french - canada",
     -- [0x040c] = "french - france",
     -- [0x140c] = "french - luxembourg",
     -- [0x180c] = "french - principality of monoco",
     -- [0x100c] = "french - switzerland",
     -- [0x0462] = "frisian - netherlands",
     -- [0x0456] = "galician - galician",
     -- [0x0437] = "georgian -georgia",
     -- [0x0c07] = "german - austria",
     -- [0x0407] = "german - germany",
     -- [0x1407] = "german - liechtenstein",
     -- [0x1007] = "german - luxembourg",
     -- [0x0807] = "german - switzerland",
     -- [0x0408] = "greek - greece",
     -- [0x046f] = "greenlandic - greenland",
     -- [0x0447] = "gujarati - india",
     -- [0x0468] = "hausa (latin) - nigeria",
     -- [0x040d] = "hebrew - israel",
     -- [0x0439] = "hindi - india",
     -- [0x040e] = "hungarian - hungary",
     -- [0x040f] = "icelandic - iceland",
     -- [0x0470] = "igbo - nigeria",
     -- [0x0421] = "indonesian - indonesia",
     -- [0x045d] = "inuktitut - canada",
     -- [0x085d] = "inuktitut (latin) - canada",
     -- [0x083c] = "irish - ireland",
     -- [0x0434] = "isixhosa - south africa",
     -- [0x0435] = "isizulu - south africa",
     -- [0x0410] = "italian - italy",
     -- [0x0810] = "italian - switzerland",
     -- [0x0411] = "japanese - japan",
     -- [0x044b] = "kannada - india",
     -- [0x043f] = "kazakh - kazakhstan",
     -- [0x0453] = "khmer - cambodia",
     -- [0x0486] = "k'iche - guatemala",
     -- [0x0487] = "kinyarwanda - rwanda",
     -- [0x0441] = "kiswahili - kenya",
     -- [0x0457] = "konkani - india",
     -- [0x0412] = "korean - korea",
     -- [0x0440] = "kyrgyz - kyrgyzstan",
     -- [0x0454] = "lao - lao p.d.r.",
     -- [0x0426] = "latvian - latvia",
     -- [0x0427] = "lithuanian - lithuania",
     -- [0x082e] = "lower sorbian - germany",
     -- [0x046e] = "luxembourgish - luxembourg",
     -- [0x042f] = "macedonian (fyrom) - former yugoslav republic of macedonia",
     -- [0x083e] = "malay - brunei darussalam",
     -- [0x043e] = "malay - malaysia",
     -- [0x044c] = "malayalam - india",
     -- [0x043a] = "maltese - malta",
     -- [0x0481] = "maori - new zealand",
     -- [0x047a] = "mapudungun - chile",
     -- [0x044e] = "marathi - india",
     -- [0x047c] = "mohawk - mohawk",
     -- [0x0450] = "mongolian (cyrillic) - mongolia",
     -- [0x0850] = "mongolian (traditional) - people's republic of china",
     -- [0x0461] = "nepali - nepal",
     -- [0x0414] = "norwegian (bokmal) - norway",
     -- [0x0814] = "norwegian (nynorsk) - norway",
     -- [0x0482] = "occitan - france",
     -- [0x0448] = "odia (formerly oriya) - india",
     -- [0x0463] = "pashto - afghanistan",
     -- [0x0415] = "polish - poland",
     -- [0x0416] = "portuguese - brazil",
     -- [0x0816] = "portuguese - portugal",
     -- [0x0446] = "punjabi - india",
     -- [0x046b] = "quechua - bolivia",
     -- [0x086b] = "quechua - ecuador",
     -- [0x0c6b] = "quechua - peru",
     -- [0x0418] = "romanian - romania",
     -- [0x0417] = "romansh - switzerland",
     -- [0x0419] = "russian - russia",
     -- [0x243b] = "sami (inari) - finland",
     -- [0x103b] = "sami (lule) - norway",
     -- [0x143b] = "sami (lule) - sweden",
     -- [0x0c3b] = "sami (northern) - finland",
     -- [0x043b] = "sami (northern) - norway",
     -- [0x083b] = "sami (northern) - sweden",
     -- [0x203b] = "sami (skolt) - finland",
     -- [0x183b] = "sami (southern) - norway",
     -- [0x1c3b] = "sami (southern) - sweden",
     -- [0x044f] = "sanskrit - india",
     -- [0x1c1a] = "serbian (cyrillic) - bosnia and herzegovina",
     -- [0x0c1a] = "serbian (cyrillic) - serbia",
     -- [0x181a] = "serbian (latin) - bosnia and herzegovina",
     -- [0x081a] = "serbian (latin) - serbia",
     -- [0x046c] = "sesotho sa leboa - south africa",
     -- [0x0432] = "setswana - south africa",
     -- [0x045b] = "sinhala - sri lanka",
     -- [0x041b] = "slovak - slovakia",
     -- [0x0424] = "slovenian - slovenia",
     -- [0x2c0a] = "spanish - argentina",
     -- [0x400a] = "spanish - bolivia",
     -- [0x340a] = "spanish - chile",
     -- [0x240a] = "spanish - colombia",
     -- [0x140a] = "spanish - costa rica",
     -- [0x1c0a] = "spanish - dominican republic",
     -- [0x300a] = "spanish - ecuador",
     -- [0x440a] = "spanish - el salvador",
     -- [0x100a] = "spanish - guatemala",
     -- [0x480a] = "spanish - honduras",
     -- [0x080a] = "spanish - mexico",
     -- [0x4c0a] = "spanish - nicaragua",
     -- [0x180a] = "spanish - panama",
     -- [0x3c0a] = "spanish - paraguay",
     -- [0x280a] = "spanish - peru",
     -- [0x500a] = "spanish - puerto rico",
     -- [0x0c0a] = "spanish (modern sort) - spain",
     -- [0x040a] = "spanish (traditional sort) - spain",
     -- [0x540a] = "spanish - united states",
     -- [0x380a] = "spanish - uruguay",
     -- [0x200a] = "spanish - venezuela",
     -- [0x081d] = "sweden - finland",
     -- [0x041d] = "swedish - sweden",
     -- [0x045a] = "syriac - syria",
     -- [0x0428] = "tajik (cyrillic) - tajikistan",
     -- [0x085f] = "tamazight (latin) - algeria",
     -- [0x0449] = "tamil - india",
     -- [0x0444] = "tatar - russia",
     -- [0x044a] = "telugu - india",
     -- [0x041e] = "thai - thailand",
     -- [0x0451] = "tibetan - prc",
     -- [0x041f] = "turkish - turkey",
     -- [0x0442] = "turkmen - turkmenistan",
     -- [0x0480] = "uighur - prc",
     -- [0x0422] = "ukrainian - ukraine",
     -- [0x042e] = "upper sorbian - germany",
     -- [0x0420] = "urdu - islamic republic of pakistan",
     -- [0x0843] = "uzbek (cyrillic) - uzbekistan",
     -- [0x0443] = "uzbek (latin) - uzbekistan",
     -- [0x042a] = "vietnamese - vietnam",
     -- [0x0452] = "welsh - united kingdom",
     -- [0x0488] = "wolof - senegal",
     -- [0x0485] = "yakut - russia",
     -- [0x0478] = "yi - prc",
     -- [0x046a] = "yoruba - nigeria",
    },
    custom = {
    },
}

local standardromanencoding = { [0] = -- taken from wikipedia
    "notdef", ".null", "nonmarkingreturn", "space", "exclam", "quotedbl",
    "numbersign", "dollar", "percent", "ampersand", "quotesingle", "parenleft",
    "parenright", "asterisk", "plus", "comma", "hyphen", "period", "slash",
    "zero", "one", "two", "three", "four", "five", "six", "seven", "eight",
    "nine", "colon", "semicolon", "less", "equal", "greater", "question", "at",
    "A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O",
    "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z", "bracketleft",
    "backslash", "bracketright", "asciicircum", "underscore", "grave", "a", "b",
    "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", "n", "o", "p", "q",
    "r", "s", "t", "u", "v", "w", "x", "y", "z", "braceleft", "bar",
    "braceright", "asciitilde", "Adieresis", "Aring", "Ccedilla", "Eacute",
    "Ntilde", "Odieresis", "Udieresis", "aacute", "agrave", "acircumflex",
    "adieresis", "atilde", "aring", "ccedilla", "eacute", "egrave",
    "ecircumflex", "edieresis", "iacute", "igrave", "icircumflex", "idieresis",
    "ntilde", "oacute", "ograve", "ocircumflex", "odieresis", "otilde", "uacute",
    "ugrave", "ucircumflex", "udieresis", "dagger", "degree", "cent", "sterling",
    "section", "bullet", "paragraph", "germandbls", "registered", "copyright",
    "trademark", "acute", "dieresis", "notequal", "AE", "Oslash", "infinity",
    "plusminus", "lessequal", "greaterequal", "yen", "mu", "partialdiff",
    "summation", "product", "pi", "integral", "ordfeminine", "ordmasculine",
    "Omega", "ae", "oslash", "questiondown", "exclamdown", "logicalnot",
    "radical", "florin", "approxequal", "Delta", "guillemotleft",
    "guillemotright", "ellipsis", "nonbreakingspace", "Agrave", "Atilde",
    "Otilde", "OE", "oe", "endash", "emdash", "quotedblleft", "quotedblright",
    "quoteleft", "quoteright", "divide", "lozenge", "ydieresis", "Ydieresis",
    "fraction", "currency", "guilsinglleft", "guilsinglright", "fi", "fl",
    "daggerdbl", "periodcentered", "quotesinglbase", "quotedblbase",
    "perthousand", "Acircumflex", "Ecircumflex", "Aacute", "Edieresis", "Egrave",
    "Iacute", "Icircumflex", "Idieresis", "Igrave", "Oacute", "Ocircumflex",
    "apple", "Ograve", "Uacute", "Ucircumflex", "Ugrave", "dotlessi",
    "circumflex", "tilde", "macron", "breve", "dotaccent", "ring", "cedilla",
    "hungarumlaut", "ogonek", "caron", "Lslash", "lslash", "Scaron", "scaron",
    "Zcaron", "zcaron", "brokenbar", "Eth", "eth", "Yacute", "yacute", "Thorn",
    "thorn", "minus", "multiply", "onesuperior", "twosuperior", "threesuperior",
    "onehalf", "onequarter", "threequarters", "franc", "Gbreve", "gbreve",
    "Idotaccent", "Scedilla", "scedilla", "Cacute", "cacute", "Ccaron", "ccaron",
    "dcroat",
}

local weights = {
    [100] = "thin",
    [200] = "extralight",
    [300] = "light",
    [400] = "normal",
    [500] = "medium",
    [600] = "semibold",
    [700] = "bold",
    [800] = "extrabold",
    [900] = "black",
}

local widths = {
    [1] = "ultracondensed",
    [2] = "extracondensed",
    [3] = "condensed",
    [4] = "semicondensed",
    [5] = "normal",
    [6] = "semiexpanded",
    [7] = "expanded",
    [8] = "extraexpanded",
    [9] = "ultraexpanded",
}

setmetatableindex(weights, function(t,k)
    local r = floor((k + 50) / 100) * 100
    local v = (r > 900 and "black") or rawget(t,r) or "normal"
-- print("weight:",k,r,v)
    return v
end)

setmetatableindex(widths,function(t,k)
-- print("width:",k)
    return "normal"
end)

local panoseweights = {
    [ 0] = "normal",
    [ 1] = "normal",
    [ 2] = "verylight",
    [ 3] = "light",
    [ 4] = "thin",
    [ 5] = "book",
    [ 6] = "medium",
    [ 7] = "demi",
    [ 8] = "bold",
    [ 9] = "heavy",
    [10] = "black",
}

local panosewidths = {
    [ 0] = "normal",
    [ 1] = "normal",
    [ 2] = "normal",
    [ 3] = "normal",
    [ 4] = "normal",
    [ 5] = "expanded",
    [ 6] = "condensed",
    [ 7] = "veryexpanded",
    [ 8] = "verycondensed",
    [ 9] = "monospaced",
}

-- We implement a reader per table.

-- The name table is probably the first one to load. After all this one provides
-- useful information about what we deal with. The complication is that we need
-- to filter the best one available.

local platformnames = {
    postscriptname       = true,
    fullname             = true,
    family               = true,
    subfamily            = true,
    typographicfamily    = true,
    typographicsubfamily = true,
    compatiblefullname   = true,
}

function readers.name(f,fontdata,specification)
    local datatable = fontdata.tables.name
    if datatable then
        setposition(f,datatable.offset)
        local format   = readushort(f)
        local nofnames = readushort(f)
        local offset   = readushort(f)
        -- we can also provide a raw list as extra, todo as option
        local start    = datatable.offset + offset
        local namelists = {
            unicode   = { },
            windows   = { },
            macintosh = { },
         -- iso       = { },
         -- windows   = { },
        }
        for i=1,nofnames do
            local platform = platforms[readushort(f)]
            if platform then
                local namelist = namelists[platform]
                if namelist then
                    local encoding  = readushort(f)
                    local language  = readushort(f)
                    local encodings = encodings[platform]
                    local languages = languages[platform]
                    if encodings and languages then
                        local encoding = encodings[encoding]
                        local language = languages[language]
                        if encoding and language then
                            local name = reservednames[readushort(f)]
                            if name then
                                namelist[#namelist+1] = {
                                    platform = platform,
                                    encoding = encoding,
                                    language = language,
                                    name     = name,
                                    length   = readushort(f),
                                    offset   = start + readushort(f),
                                }
                            else
                                skipshort(f,2)
                            end
                        else
                            skipshort(f,3)
                        end
                    else
                        skipshort(f,3)
                    end
                else
                    skipshort(f,5)
                end
            else
                skipshort(f,5)
            end
        end
     -- if format == 1 then
     --     local noftags = readushort(f)
     --     for i=1,noftags do
     --        local length = readushort(f)
     --        local offset = readushort(f)
     --     end
     -- end
        --
        -- we need to choose one we like, for instance an unicode one
        --
        local names = { }
        local done  = { }
        --
        -- there is quite some logic in ff ... hard to follow so we start simple
        -- and extend when we run into it (todo: proper reverse hash) .. we're only
        -- interested in english anyway
        --
        local function filter(platform,e,l)
            local namelist = namelists[platform]
            for i=1,#namelist do
                local name    = namelist[i]
                local nametag = name.name
                if not done[nametag] then
                    local encoding = name.encoding
                    local language = name.language
                    if (not e or encoding == e) and (not l or language == l) then
                        setposition(f,name.offset)
                        local content = readstring(f,name.length)
                        local decoder = decoders[platform]
                        if decoder then
                            decoder = decoder[encoding]
                        end
                        if decoder then
                            content = decoder(content)
                        end
                        names[nametag] = {
                            content  = content,
                            platform = platform,
                            encoding = encoding,
                            language = language,
                        }
                        done[nametag] = true
                    end
                end
            end
        end
        --
        filter("windows","unicode bmp","english - united states")
     -- filter("unicode") -- which one ?
        filter("macintosh","roman","english")
        filter("windows")
        filter("macintosh")
        filter("unicode")
        --
        fontdata.names = names
        --
        if specification.platformnames then
            local collected = { }
            for platform, namelist in next, namelists do
                local filtered = false
                for i=1,#namelist do
                    local entry = namelist[i]
                    local name  = entry.name
                    if platformnames[name] then
                        setposition(f,entry.offset)
                        local content  = readstring(f,entry.length)
                        local encoding = entry.encoding
                        local decoder  = decoders[platform]
                        if decoder then
                            decoder = decoder[encoding]
                        end
                        if decoder then
                            content = decoder(content)
                        end
                        if filtered then
                            filtered[name] = content
                        else
                            filtered = { [name] = content }
                        end
                    end
                end
                if filtered then
                    collected[platform] = filtered
                end
            end
            fontdata.platformnames = collected
        end
    else
        fontdata.names = { }
    end
end

----- validutf = lpeg.patterns.utf8character^0 * P(-1)
local validutf = lpeg.patterns.validutf8

local function getname(fontdata,key)
    local names = fontdata.names
    if names then
        local value = names[key]
        if value then
            local content = value.content
            return lpegmatch(validutf,content) and content or nil
        end
    end
end

-- This table is an original windows (with its precursor os/2) table. In ff this one is
-- part of the pfminfo table but here we keep it separate (for now). We will create a
-- properties table afterwards.

readers["os/2"] = function(f,fontdata)
    local datatable = fontdata.tables["os/2"]
    if datatable then
        setposition(f,datatable.offset)
        local version = readushort(f)
        local windowsmetrics = {
            version            = version,
            averagewidth       = readshort(f),
            weightclass        = readushort(f),
            widthclass         = readushort(f),
            fstype             = readushort(f),
            subscriptxsize     = readshort(f),
            subscriptysize     = readshort(f),
            subscriptxoffset   = readshort(f),
            subscriptyoffset   = readshort(f),
            superscriptxsize   = readshort(f),
            superscriptysize   = readshort(f),
            superscriptxoffset = readshort(f),
            superscriptyoffset = readshort(f),
            strikeoutsize      = readshort(f),
            strikeoutpos       = readshort(f),
            familyclass        = readshort(f),
            panose             = { readbytes(f,10) },
            unicoderanges      = { readulong(f), readulong(f), readulong(f), readulong(f) },
            vendor             = readstring(f,4),
            fsselection        = readushort(f),
            firstcharindex     = readushort(f),
            lastcharindex      = readushort(f),
            typoascender       = readshort(f),
            typodescender      = readshort(f),
            typolinegap        = readshort(f),
            winascent          = readushort(f),
            windescent         = readushort(f),
        }
        if version >= 1 then
            windowsmetrics.codepageranges = { readulong(f), readulong(f) }
        end
        if version >= 3 then
            windowsmetrics.xheight               = readshort(f)
            windowsmetrics.capheight             = readshort(f)
            windowsmetrics.defaultchar           = readushort(f)
            windowsmetrics.breakchar             = readushort(f)
         -- windowsmetrics.maxcontexts           = readushort(f)
         -- windowsmetrics.loweropticalpointsize = readushort(f)
         -- windowsmetrics.upperopticalpointsize = readushort(f)
        end
        --
        -- todo: unicoderanges
        --
        windowsmetrics.weight = windowsmetrics.weightclass and weights[windowsmetrics.weightclass]
        windowsmetrics.width  = windowsmetrics.widthclass and  widths [windowsmetrics.widthclass]
        --
        windowsmetrics.panoseweight = panoseweights[windowsmetrics.panose[3]]
        windowsmetrics.panosewidth  = panosewidths [windowsmetrics.panose[4]]
        --
        fontdata.windowsmetrics = windowsmetrics
    else
        fontdata.windowsmetrics = { }
    end
end

readers.head = function(f,fontdata)
    local datatable = fontdata.tables.head
    if datatable then
        setposition(f,datatable.offset)
        local fontheader = {
            version          = readfixed(f),
            revision         = readfixed(f),
            checksum         = readulong(f),
            magic            = readulong(f),
            flags            = readushort(f),
            units            = readushort(f),
            created          = readlongdatetime(f),
            modified         = readlongdatetime(f),
            xmin             = readshort(f),
            ymin             = readshort(f),
            xmax             = readshort(f),
            ymax             = readshort(f),
            macstyle         = readushort(f),
            smallpixels      = readushort(f),
            directionhint    = readshort(f),
            indextolocformat = readshort(f),
            glyphformat      = readshort(f),
        }
        fontdata.fontheader = fontheader
    else
        fontdata.fontheader = { }
    end
    fontdata.nofglyphs = 0
end

-- This table is a rather simple one. No treatment of values is needed here. Most
-- variables are not used but nofmetrics is quite important.

readers.hhea = function(f,fontdata,specification)
    if specification.details then
        local datatable = fontdata.tables.hhea
        if datatable then
            setposition(f,datatable.offset)
            fontdata.horizontalheader = {
                version             = readfixed(f), -- two ushorts: major minor
                ascender            = readfword(f),
                descender           = readfword(f),
                linegap             = readfword(f),
                maxadvancewidth     = readufword(f),
                minleftsidebearing  = readfword(f),
                minrightsidebearing = readfword(f),
                maxextent           = readfword(f),
                caretsloperise      = readshort(f),
                caretsloperun       = readshort(f),
                caretoffset         = readshort(f),
                reserved_1          = readshort(f),
                reserved_2          = readshort(f),
                reserved_3          = readshort(f),
                reserved_4          = readshort(f),
                metricdataformat    = readshort(f),
                nofmetrics          = readushort(f),
            }
        else
            fontdata.horizontalheader = {
                nofmetrics = 0,
            }
        end
    end
end

readers.vhea = function(f,fontdata,specification)
    if specification.details then
        local datatable = fontdata.tables.vhea
        if datatable then
            setposition(f,datatable.offset)
            local version = readfixed(f)
            fontdata.verticalheader = {
                version              = version,
                ascender             = readfword(f),
                descender            = readfword(f),
                linegap              = readfword(f),
                maxadvanceheight     = readufword(f),
                mintopsidebearing    = readfword(f),
                minbottomsidebearing = readfword(f),
                maxextent            = readfword(f),
                caretsloperise       = readshort(f),
                caretsloperun        = readshort(f),
                caretoffset          = readshort(f),
                reserved_1           = readshort(f),
                reserved_2           = readshort(f),
                reserved_3           = readshort(f),
                reserved_4           = readshort(f),
                metricdataformat     = readshort(f),
                nofmetrics           = readushort(f),
            }
--             inspect(fontdata.verticalheader)
        else
            fontdata.verticalheader = {
                nofmetrics = 0,
            }
        end
    end
end

-- We probably never need all these variables, but we do need the nofglyphs when loading other
-- tables. Again we use the microsoft names but see no reason to have "max" in each name.

-- fontdata.maximumprofile can be bad

readers.maxp = function(f,fontdata,specification)
    if specification.details then
        local datatable = fontdata.tables.maxp
        if datatable then
            setposition(f,datatable.offset)
            local version      = readfixed(f)
            local nofglyphs    = readushort(f)
            fontdata.nofglyphs = nofglyphs
            if version == 0.5 then
                fontdata.maximumprofile = {
                    version   = version,
                    nofglyphs = nofglyphs,
                }
                return
            elseif version == 1.0 then
                fontdata.maximumprofile = {
                    version            = version,
                    nofglyphs          = nofglyphs,
                    points             = readushort(f),
                    contours           = readushort(f),
                    compositepoints    = readushort(f),
                    compositecontours  = readushort(f),
                    zones              = readushort(f),
                    twilightpoints     = readushort(f),
                    storage            = readushort(f),
                    functiondefs       = readushort(f),
                    instructiondefs    = readushort(f),
                    stackelements      = readushort(f),
                    sizeofinstructions = readushort(f),
                    componentelements  = readushort(f),
                    componentdepth     = readushort(f),
                }
                return
            end
        end
        fontdata.maximumprofile = {
            version   = version,
            nofglyphs = 0,
        }
    end
end

-- Here we filter the (advance) widths (that can be different from the boundingbox width of
-- course).

readers.hmtx = function(f,fontdata,specification)
    if specification.glyphs then
        local datatable = fontdata.tables.hmtx
        if datatable then
            setposition(f,datatable.offset)
            local horizontalheader = fontdata.horizontalheader
            local nofmetrics       = horizontalheader.nofmetrics
            local glyphs           = fontdata.glyphs
            local nofglyphs        = fontdata.nofglyphs
            local width            = 0 -- advance
            local leftsidebearing  = 0
            for i=0,nofmetrics-1 do
                local glyph     = glyphs[i]
                width           = readshort(f)
                leftsidebearing = readshort(f)
                if width ~= 0 then
                    glyph.width = width
                end
             -- if leftsidebearing ~= 0 then
             --     glyph.lsb = leftsidebearing
             -- end
            end
            -- The next can happen in for instance a monospace font or in a cjk font
            -- with fixed widths.
            for i=nofmetrics,nofglyphs-1 do
                local glyph = glyphs[i]
                if width ~= 0 then
                    glyph.width = width
                end
             -- if leftsidebearing ~= 0 then
             --     glyph.lsb = leftsidebearing
             -- end
            end
        end
    end
end

readers.vmtx = function(f,fontdata,specification)
    if specification.glyphs then
        local datatable = fontdata.tables.vmtx
        if datatable then
            setposition(f,datatable.offset)
            local verticalheader = fontdata.verticalheader
            local nofmetrics     = verticalheader.nofmetrics
            local glyphs         = fontdata.glyphs
            local nofglyphs      = fontdata.nofglyphs
            local vheight        = 0
            local vdefault       = verticalheader.ascender + verticalheader.descender
            local topsidebearing = 0
            for i=0,nofmetrics-1 do
                local glyph     = glyphs[i]
                vheight         = readshort(f)
                topsidebearing  = readshort(f)
                if vheight ~= 0 and vheight ~= vdefault then
                    glyph.vheight = vheight
                end
             -- if topsidebearing ~= 0 then
             --     glyph.tsb = topsidebearing
             -- end
            end
            -- The next can happen in for instance a monospace font or in a cjk font
            -- with fixed heights.
            for i=nofmetrics,nofglyphs-1 do
                local glyph = glyphs[i]
                if vheight ~= 0 and vheight ~= vdefault then
                    glyph.vheight = vheight
                end
             -- if topsidebearing ~= 0 then
             --     glyph.tsb = topsidebearing
             -- end
            end
        end
    end
end

readers.vorg = function(f,fontdata,specification)
    if specification.glyphs then
        local datatable = fontdata.tables.vorg
        if datatable then
            report("todo: %s","vorg")
        end
    end
end

-- The post table relates to postscript (printing) but has some relevant properties for other
-- usage as well. We just use the names from the microsoft specification. The version 2.0
-- description is somewhat fuzzy but it is a hybrid with overloads.

readers.post = function(f,fontdata,specification)
    local datatable = fontdata.tables.post
    if datatable then
        setposition(f,datatable.offset)
        local version = readfixed(f)
        fontdata.postscript = {
            version            = version,
            italicangle        = round(1000*readfixed(f))/1000,
            underlineposition  = readfword(f),
            underlinethickness = readfword(f),
            monospaced         = readulong(f),
            minmemtype42       = readulong(f),
            maxmemtype42       = readulong(f),
            minmemtype1        = readulong(f),
            maxmemtype1        = readulong(f),
        }
        if not specification.glyphs then
            -- enough done
        elseif version == 1.0 then
            -- mac encoding (258 glyphs)
            for index=0,#standardromanencoding do
                glyphs[index].name = standardromanencoding[index]
            end
        elseif version == 2.0 then
            local glyphs    = fontdata.glyphs
            local nofglyphs = readushort(f)
            local indices   = { }
            local names     = { }
            local maxnames  = 0
            for i=0,nofglyphs-1 do
                local nameindex = readushort(f)
                if nameindex >= 258 then
                    maxnames = maxnames + 1
                    nameindex = nameindex - 257
                    indices[nameindex] = i
                else
                    glyphs[i].name = standardromanencoding[nameindex]
                end
            end
            for i=1,maxnames do
                local mapping = indices[i]
                if not mapping then
                    report("quit post name fetching at %a of %a: %s",i,maxnames,"no index")
                    break
                else
                    local length  = readbyte(f)
                    if length > 0 then
                        glyphs[mapping].name = readstring(f,length)
                    else
                        report("quit post name fetching at %a of %a: %s",i,maxnames,"overflow")
                        break
                    end
                end
            end
        elseif version == 2.5 then
            -- depricated, will be done when needed
        elseif version == 3.0 then
            -- no ps name information
        end
    else
        fontdata.postscript = { }
    end
end

readers.cff = function(f,fontdata,specification)
    if specification.glyphs then
        reportskippedtable("cff")
    end
end

-- Not all cmaps make sense .. e.g. dfont is obsolete and probably more are not relevant. Let's see
-- what we run into. There is some weird calculation going on here because we offset in a table
-- being a blob of memory or file. Anyway, I can't stand lunatic formats like this esp when there
-- is no real gain.

local formatreaders = { }
local duplicatestoo = true

local sequence = {
    { 3,  1,  4 },
    { 3, 10, 12 },
    { 0,  3,  4 },
    { 0,  1,  4 },
 -- { 0,  4, 12 },
    { 0,  0,  6 },
    { 3,  0,  6 },
    -- variants
    { 0,  5, 14 },
    -- last resort ranges
    { 3, 10, 13 },
}

-- local sequence = {
--     { 0,  1,  4 },
--     { 0,  4, 12 },
--     { 0,  3,  4 },
--     { 3,  1,  4 },
--     { 3, 10, 12 },
--     { 0,  0,  6 },
--     { 3,  0,  6 },
--     -- variants
--     { 0,  5, 14 },
-- }

local supported = {  }

for i=1,#sequence do
    local sp, se, sf = unpack(sequence[i])
    local p = supported[sp]
    if not p then
        p = { }
        supported[sp] = p
    end
    local e = p[se]
    if not e then
        e = { }
        p[se] = e
    end
    e[sf] = true
end

formatreaders[4] = function(f,fontdata,offset)
    setposition(f,offset+2) -- skip format
    --
    local length      = readushort(f) -- in bytes of subtable
    local language    = readushort(f)
    local nofsegments = readushort(f) / 2
    --
    skipshort(f,3) -- searchrange entryselector rangeshift
    --
    local endchars   = { }
    local startchars = { }
    local deltas     = { }
    local offsets    = { }
    local indices    = { }
    local mapping    = fontdata.mapping
    local glyphs     = fontdata.glyphs
    local duplicates = fontdata.duplicates
    local nofdone    = 0
    --
    for i=1,nofsegments do
        endchars[i] = readushort(f)
    end
    local reserved = readushort(f) -- 0
    for i=1,nofsegments do
        startchars[i] = readushort(f)
    end
    for i=1,nofsegments do
        deltas[i] = readshort(f)
    end
    for i=1,nofsegments do
        offsets[i] = readushort(f)
    end
    -- format length language nofsegments searchrange entryselector rangeshift 4-tables
    local size = (length - 2 * 2 - 5 * 2 - 4 * nofsegments * 2) / 2
    for i=1,size-1 do
        indices[i] = readushort(f)
    end
    --
    for segment=1,nofsegments do
        local startchar = startchars[segment]
        local endchar   = endchars[segment]
        local offset    = offsets[segment]
        local delta     = deltas[segment]
        if startchar == 0xFFFF and endchar == 0xFFFF then
            -- break
        elseif startchar == 0xFFFF and offset == 0 then
            -- break
        elseif offset == 0xFFFF then
            -- bad encoding
        elseif offset == 0 then
            if trace_cmap then
                report("format 4.%i segment %2i from %C upto %C at index %H",1,segment,startchar,endchar,(startchar + delta) % 65536)
            end
            for unicode=startchar,endchar do
                local index = (unicode + delta) % 65536
                if index and index > 0 then
                    local glyph = glyphs[index]
                    if glyph then
                        local gu = glyph.unicode
                        if not gu then
                            glyph.unicode = unicode
                            nofdone = nofdone + 1
                        elseif gu ~= unicode then
                            if duplicatestoo then
                                local d = duplicates[gu]
                                if d then
                                    d[unicode] = true
                                else
                                    duplicates[gu] = { [unicode] = true }
                                end
                            else
                                -- no duplicates ... weird side effects in lm
                                report("duplicate case 1: %C %04i %s",unicode,index,glyphs[index].name)
                            end
                        end
                        if not mapping[index] then
                            mapping[index] = unicode
                        end
                    end
                end
            end
        else
            local shift = (segment-nofsegments+offset/2) - startchar
            if trace_cmap then
                report("format 4.%i segment %2i from %C upto %C at index %H",0,segment,startchar,endchar,(startchar + delta) % 65536)
            end
            for unicode=startchar,endchar do
                local slot  = shift + unicode
                local index = indices[slot]
                if index and index > 0 then
                    index = (index + delta) % 65536
                    local glyph = glyphs[index]
                    if glyph then
                        local gu = glyph.unicode
                        if not gu then
                            glyph.unicode = unicode
                            nofdone = nofdone + 1
                        elseif gu ~= unicode then
                            if duplicatestoo then
                                local d = duplicates[gu]
                                if d then
                                    d[unicode] = true
                                else
                                    duplicates[gu] = { [unicode] = true }
                                end
                            else
                                -- no duplicates ... weird side effects in lm
                                report("duplicate case 2: %C %04i %s",unicode,index,glyphs[index].name)
                            end
                        end
                        if not mapping[index] then
                            mapping[index] = unicode
                        end
                    end
                end
            end
        end
    end
    return nofdone
end

formatreaders[6] = function(f,fontdata,offset)
    setposition(f,offset) -- + 2 + 2 + 2 -- skip format length language
    local format     = readushort(f)
    local length     = readushort(f)
    local language   = readushort(f)
    local mapping    = fontdata.mapping
    local glyphs     = fontdata.glyphs
    local duplicates = fontdata.duplicates
    local start      = readushort(f)
    local count      = readushort(f)
    local stop       = start+count-1
    local nofdone    = 0
    if trace_cmap then
        report("format 6 from %C to %C",2,start,stop)
    end
    for unicode=start,stop do
        local index = readushort(f)
        if index > 0 then
            local glyph = glyphs[index]
            if glyph then
                local gu = glyph.unicode
                if not gu then
                    glyph.unicode = unicode
                    nofdone = nofdone + 1
                elseif gu ~= unicode then
                    -- report("format 6 overloading %C to %C",gu,unicode)
                    -- glyph.unicode = unicode
                    -- no duplicates ... weird side effects in lm
                end
                if not mapping[index] then
                    mapping[index] = unicode
                end
            end
        end
    end
    return nofdone
end

formatreaders[12] = function(f,fontdata,offset)
    setposition(f,offset+2+2+4+4) -- skip format reserved length language
    local mapping    = fontdata.mapping
    local glyphs     = fontdata.glyphs
    local duplicates = fontdata.duplicates
    local nofgroups  = readulong(f)
    local nofdone    = 0
    for i=1,nofgroups do
        local first = readulong(f)
        local last  = readulong(f)
        local index = readulong(f)
        if trace_cmap then
            report("format 12 from %C to %C starts at index %i",first,last,index)
        end
        for unicode=first,last do
            local glyph = glyphs[index]
            if glyph then
                local gu = glyph.unicode
                if not gu then
                    glyph.unicode = unicode
                    nofdone = nofdone + 1
                elseif gu ~= unicode then
                    -- e.g. sourcehan fonts need this
                    local d = duplicates[gu]
                    if d then
                        d[unicode] = true
                    else
                        duplicates[gu] = { [unicode] = true }
                    end
                end
                if not mapping[index] then
                    mapping[index] = unicode
                end
            end
            index = index + 1
        end
    end
    return nofdone
end

formatreaders[13] = function(f,fontdata,offset)
    --
    -- this fector is only used for simple fallback fonts
    --
    setposition(f,offset+2+2+4+4) -- skip format reserved length language
    local mapping    = fontdata.mapping
    local glyphs     = fontdata.glyphs
    local duplicates = fontdata.duplicates
    local nofgroups  = readulong(f)
    local nofdone    = 0
    for i=1,nofgroups do
        local first = readulong(f)
        local last  = readulong(f)
        local index = readulong(f)
        if first < privateoffset then
            if trace_cmap then
                report("format 13 from %C to %C get index %i",first,last,index)
            end
            local glyph   = glyphs[index]
            local unicode = glyph.unicode
            if not unicode then
                unicode = first
                glyph.unicode = unicode
                first = first + 1
            end
            local list     = duplicates[unicode]
            mapping[index] = unicode
            if not list then
                list = { }
                duplicates[unicode] = list
            end
            if last >= privateoffset then
                local limit = privateoffset - 1
                report("format 13 from %C to %C pruned to %C",first,last,limit)
                last = limit
            end
            for unicode=first,last do
                list[unicode] = true
            end
            nofdone = nofdone + last - first + 1
        else
            report("format 13 from %C to %C ignored",first,last)
        end
    end
    return nofdone
end

formatreaders[14] = function(f,fontdata,offset)
    if offset and offset ~= 0 then
        setposition(f,offset)
        local format      = readushort(f)
        local length      = readulong(f)
        local nofrecords  = readulong(f)
        local records     = { }
        local variants    = { }
        local nofdone     = 0
        fontdata.variants = variants
        for i=1,nofrecords do
            records[i] = {
                selector = readuint(f),
                default  = readulong(f), -- default offset
                other    = readulong(f), -- non-default offset
            }
        end
        for i=1,nofrecords do
            local record   = records[i]
            local selector = record.selector
            local default  = record.default
            local other    = record.other
            --
            -- there is no need to map the defaults to themselves
            --
         -- if default ~= 0 then
         --     setposition(f,offset+default)
         --     local nofranges = readulong(f)
         --     for i=1,nofranges do
         --         local start = readuint(f)
         --         local extra = readbyte(f)
         --         for i=start,start+extra do
         --             mapping[i] = i
         --         end
         --     end
         -- end
            local other = record.other
            if other ~= 0 then
                setposition(f,offset+other)
                local mapping = { }
                local count   = readulong(f)
                for i=1,count do
                    mapping[readuint(f)] = readushort(f)
                end
                nofdone = nofdone + count
                variants[selector] = mapping
            end
        end
        return nofdone
    else
        return 0
    end
end

local function checkcmap(f,fontdata,records,platform,encoding,format)
    local data = records[platform]
    if not data then
        return 0
    end
    data = data[encoding]
    if not data then
        return 0
    end
    data = data[format]
    if not data then
        return 0
    end
    local reader = formatreaders[format]
    if not reader then
        return 0
    end
    local p = platforms[platform]
    local e = encodings[p]
    local n = reader(f,fontdata,data) or 0
    report("cmap checked: platform %i (%s), encoding %i (%s), format %i, new unicodes %i",platform,p,encoding,e and e[encoding] or "?",format,n)
    return n
end

function readers.cmap(f,fontdata,specification)
    if specification.glyphs then
        local datatable = fontdata.tables.cmap
        if datatable then
            local tableoffset = datatable.offset
            setposition(f,tableoffset)
            local version      = readushort(f)
            local noftables    = readushort(f)
            local records      = { }
            local unicodecid   = false
            local variantcid   = false
            local variants     = { }
            local duplicates   = fontdata.duplicates or { }
            fontdata.duplicates = duplicates
            for i=1,noftables do
                local platform = readushort(f)
                local encoding = readushort(f)
                local offset   = readulong(f)
                local record   = records[platform]
                if not record then
                    records[platform] = {
                        [encoding] = {
                            offsets = { offset },
                            formats = { },
                        }
                    }
                else
                    local subtables = record[encoding]
                    if not subtables then
                        record[encoding] = {
                            offsets = { offset },
                            formats = { },
                        }
                    else
                        local offsets = subtables.offsets
                        offsets[#offsets+1] = offset
                    end
                end
            end
            report("found cmaps:")
            for platform, record in sortedhash(records) do
                local p  = platforms[platform]
                local e  = encodings[p]
                local sp = supported[platform]
                local ps = p or "?"
                if sp then
                    report("  platform %i: %s",platform,ps)
                else
                    report("  platform %i: %s (unsupported)",platform,ps)
                end
                for encoding, subtables in sortedhash(record) do
                    local se = sp and sp[encoding]
                    local es = e and e[encoding] or "?"
                    if se then
                        report("    encoding %i: %s",encoding,es)
                    else
                        report("    encoding %i: %s (unsupported)",encoding,es)
                    end
                    local offsets = subtables.offsets
                    local formats = subtables.formats
                    for i=1,#offsets do
                        local offset = tableoffset + offsets[i]
                        setposition(f,offset)
                        formats[readushort(f)] = offset
                    end
                    record[encoding] = formats
                    local list = sortedkeys(formats)
                    for i=1,#list do
                        if not (se and se[list[i]]) then
                            list[i] = list[i] .. " (unsupported)"
                        end
                    end
                    report("      formats: % t",list)
                end
            end
            --
            local ok = false
            for i=1,#sequence do
                local sp, se, sf = unpack(sequence[i])
                if checkcmap(f,fontdata,records,sp,se,sf) > 0 then
                    ok = true
                end
            end
            if not ok then
                report("no useable unicode cmap found")
            end
            --
            fontdata.cidmaps = {
                version   = version,
                noftables = noftables,
                records   = records,
            }
        else
            fontdata.cidmaps = { }
        end
    end
end

-- The glyf table depends on the loca table. We have one entry to much in the locations table (the
-- last one is a dummy) because we need to calculate the size of a glyph blob from the delta,
-- although we not need it in our usage (yet). We can remove the locations table when we're done.

function readers.loca(f,fontdata,specification)
    if specification.glyphs then
        reportskippedtable("loca")
    end
end

function readers.glyf(f,fontdata,specification) -- part goes to cff module
    if specification.glyphs then
        reportskippedtable("glyf")
    end
end

-- Experimental (we need fonts).

function readers.colr(f,fontdata,specification)
    if specification.glyphs then
        reportskippedtable("colr")
    end
end

function readers.cpal(f,fontdata,specification)
    if specification.glyphs then
        reportskippedtable("cpal")
    end
end

function readers.svg(f,fontdata,specification)
    if specification.glyphs then
        reportskippedtable("svg")
    end
end

-- Here we have a table that we really need for later processing although a more advanced gpos table
-- can also be available. Todo: we need a 'fake' lookup for this (analogue to ff).

function readers.kern(f,fontdata,specification)
    if specification.kerns then
        local datatable = fontdata.tables.kern
        if datatable then
            setposition(f,datatable.offset)
            local version   = readushort(f)
            local noftables = readushort(f)
            for i=1,noftables do
                local version  = readushort(f)
                local length   = readushort(f)
                local coverage = readushort(f)
                -- bit 8-15 of coverage: format 0 or 2
                local format   = bit32.rshift(coverage,8) -- is this ok?
                if format == 0 then
                    local nofpairs      = readushort(f)
                    local searchrange   = readushort(f)
                    local entryselector = readushort(f)
                    local rangeshift    = readushort(f)
                    local kerns  = { }
                    local glyphs = fontdata.glyphs
                    for i=1,nofpairs do
                        local left  = readushort(f)
                        local right = readushort(f)
                        local kern  = readfword(f)
                        local glyph = glyphs[left]
                        local kerns = glyph.kerns
                        if kerns then
                            kerns[right] = kern
                        else
                            glyph.kerns = { [right] = kern }
                        end
                    end
                elseif format == 2 then
                    report("todo: kern classes")
                else
                    report("todo: kerns")
                end
            end
        end
    end
end

function readers.gdef(f,fontdata,specification)
    if specification.details then
        reportskippedtable("gdef")
    end
end

function readers.gsub(f,fontdata,specification)
    if specification.details then
        reportskippedtable("gsub")
    end
end

function readers.gpos(f,fontdata,specification)
    if specification.details then
        reportskippedtable("gpos")
    end
end

function readers.math(f,fontdata,specification)
    if specification.glyphs then
        reportskippedtable("math")
    end
end

-- Now comes the loader. The order of reading these matters as we need to know
-- some properties in order to read following tables. When details is true we also
-- initialize the glyphs data.

local function getinfo(maindata,sub,platformnames,rawfamilynames,metricstoo)
    local fontdata = sub and maindata.subfonts and maindata.subfonts[sub] or maindata
    local names    = fontdata.names
    local info     = nil
    if names then
        local metrics        = fontdata.windowsmetrics or { }
        local postscript     = fontdata.postscript     or { }
        local fontheader     = fontdata.fontheader     or { }
        local cffinfo        = fontdata.cffinfo        or { }
        local filename       = fontdata.filename
        local weight         = getname(fontdata,"weight") or cffinfo.weight or metrics.weight
        local width          = getname(fontdata,"width")  or cffinfo.width  or metrics.width
        local fontname       = getname(fontdata,"postscriptname")
        local fullname       = getname(fontdata,"fullname")
        local family         = getname(fontdata,"family")
        local subfamily      = getname(fontdata,"subfamily")
        local familyname     = getname(fontdata,"typographicfamily")
        local subfamilyname  = getname(fontdata,"typographicsubfamily")
        local compatiblename = getname(fontdata,"compatiblefullname") -- kind of useless
        if rawfamilynames then
            -- for PG (for now, as i need to check / adapt context to catch a no-fallback case)
        else
            if not    familyname then    familyname =    family end
            if not subfamilyname then subfamilyname = subfamily end
        end
        info = { -- we inherit some inconsistencies/choices from ff
            subfontindex   = fontdata.subfontindex or sub or 0,
         -- filename       = filename,
            version        = getname(fontdata,"version"),
         -- format         = fontdata.format,
            fontname       = fontname,
            fullname       = fullname,
         -- cfffullname    = cff.fullname,
            family         = family,
            subfamily      = subfamily,
            familyname     = familyname,
            subfamilyname  = subfamilyname,
            compatiblename = compatiblename,
            weight         = weight and lower(weight),
            width          = width and lower(width),
            pfmweight      = metrics.weightclass or 400, -- will become weightclass
            pfmwidth       = metrics.widthclass or 5,    -- will become widthclass
            panosewidth    = metrics.panosewidth,
            panoseweight   = metrics.panoseweight,
            italicangle    = postscript.italicangle or 0,
            units          = fontheader.units or 0,
            designsize     = fontdata.designsize,
            minsize        = fontdata.minsize,
            maxsize        = fontdata.maxsize,
            monospaced     = (tonumber(postscript.monospaced or 0) > 0) or metrics.panosewidth == "monospaced",
            averagewidth   = metrics.averagewidth,
            xheight        = metrics.xheight,
            capheight      = metrics.capheight, -- not always present and probably crap
            ascender       = metrics.typoascender,
            descender      = metrics.typodescender,
            platformnames  = platformnames and fontdata.platformnames or nil,
        }
        if metricstoo then
            local keys = {
                "version",
                "ascender", "descender", "linegap",
             -- "caretoffset", "caretsloperise", "caretsloperun",
                "maxadvancewidth", "maxadvanceheight", "maxextent",
             -- "metricdataformat",
                "minbottomsidebearing", "mintopsidebearing",
            }
            local h = fontdata.horizontalheader or { }
            local v = fontdata.verticalheader   or { }
            if h then
                local th = { }
                local tv = { }
                for i=1,#keys do
                    local key = keys[i]
                    th[key] = h[key] or 0
                    tv[key] = v[key] or 0
                end
                info.horizontalmetrics = th
                info.verticalmetrics   = tv
            end
        end
    elseif n then
        info = {
            filename = fontdata.filename,
            comment  = "there is no info for subfont " .. n,
        }
    else
        info = {
            filename = fontdata.filename,
            comment  = "there is no info",
        }
    end
 -- inspect(info)
    return info
end

local function loadtables(f,specification,offset)
    if offset then
        setposition(f,offset)
    end
    local tables   = { }
    local basename = file.basename(specification.filename)
    local filesize = specification.filesize
    local filetime = specification.filetime
    local fontdata = { -- some can/will go
        filename      = basename,
        filesize      = filesize,
        filetime      = filetime,
        version       = readstring(f,4),
        noftables     = readushort(f),
        searchrange   = readushort(f), -- not needed
        entryselector = readushort(f), -- not needed
        rangeshift    = readushort(f), -- not needed
        tables        = tables,
    }
    for i=1,fontdata.noftables do
        local tag      = lower(stripstring(readstring(f,4)))
        local checksum = readulong(f) -- not used
        local offset   = readulong(f)
        local length   = readulong(f)
        if offset + length > filesize then
            report("bad %a table in file %a",tag,basename)
        end
        tables[tag] = {
            checksum = checksum,
            offset   = offset,
            length   = length,
        }
    end
    if tables.cff then
        fontdata.format = "opentype"
    else
        fontdata.format = "truetype"
    end
    return fontdata
end

local function prepareglyps(fontdata)
    local glyphs = setmetatableindex(function(t,k)
        local v = {
            -- maybe more defaults
            index = k,
        }
        t[k] = v
        return v
    end)
    fontdata.glyphs  = glyphs
    fontdata.mapping = { }
end

local function readdata(f,offset,specification)
    local fontdata = loadtables(f,specification,offset)
    if specification.glyphs then
        prepareglyps(fontdata)
    end
    --
    readers["name"](f,fontdata,specification)
    --
    local askedname = specification.askedname
    if askedname then
        local fullname  = getname(fontdata,"fullname") or ""
        local cleanname = gsub(askedname,"[^a-zA-Z0-9]","")
        local foundname = gsub(fullname,"[^a-zA-Z0-9]","")
        if lower(cleanname) ~= lower(foundname) then
            return -- keep searching
        end
    end
    --
    --
    readers["os/2"](f,fontdata,specification)
    readers["head"](f,fontdata,specification)
    readers["maxp"](f,fontdata,specification)
    readers["hhea"](f,fontdata,specification)
    readers["vhea"](f,fontdata,specification)
    readers["hmtx"](f,fontdata,specification)
    readers["vmtx"](f,fontdata,specification)
    readers["vorg"](f,fontdata,specification)
    readers["post"](f,fontdata,specification)
    readers["cff" ](f,fontdata,specification)
    readers["cmap"](f,fontdata,specification)
    readers["loca"](f,fontdata,specification)
    readers["glyf"](f,fontdata,specification)
    readers["colr"](f,fontdata,specification)
    readers["cpal"](f,fontdata,specification)
    readers["svg" ](f,fontdata,specification)
    readers["kern"](f,fontdata,specification)
    readers["gdef"](f,fontdata,specification)
    readers["gsub"](f,fontdata,specification)
    readers["gpos"](f,fontdata,specification)
    readers["math"](f,fontdata,specification)
    --
    fontdata.locations    = nil
    fontdata.tables       = nil
    fontdata.cidmaps      = nil
    fontdata.dictionaries = nil
    -- fontdata.cff = nil
    return fontdata
end

local function loadfontdata(specification)
    local filename = specification.filename
    local fileattr = lfs.attributes(filename)
    local filesize = fileattr and fileattr.size or 0
    local filetime = fileattr and fileattr.modification or 0
    local f = openfile(filename,true) -- zero based
    if not f then
        report("unable to open %a",filename)
    elseif filesize == 0 then
        report("empty file %a",filename)
        closefile(f)
    else
        specification.filesize = filesize
        specification.filetime = filetime
        local version  = readstring(f,4)
        local fontdata = nil
        if version == "OTTO" or version == "true" or version == "\0\1\0\0" then
            fontdata = readdata(f,0,specification)
        elseif version == "ttcf" then
            local subfont     = tonumber(specification.subfont)
            local offsets     = { }
            local ttcversion  = readulong(f)
            local nofsubfonts = readulong(f)
            for i=1,nofsubfonts do
                offsets[i] = readulong(f)
            end
            if subfont then -- a number of not
                if subfont >= 1 and subfont <= nofsubfonts then
                    fontdata = readdata(f,offsets[subfont],specification)
                else
                    report("no subfont %a in file %a",subfont,filename)
                end
            else
                subfont = specification.subfont
                if type(subfont) == "string" and subfont ~= "" then
                    specification.askedname = subfont
                    for i=1,nofsubfonts do
                        fontdata = readdata(f,offsets[i],specification)
                        if fontdata then
                            fontdata.subfontindex = i
                            report("subfont named %a has index %a",subfont,i)
                            break
                        end
                    end
                    if not fontdata then
                        report("no subfont named %a",subfont)
                    end
                else
                    local subfonts = { }
                    fontdata = {
                        filename    = filename,
                        filesize    = filesize,
                        filetime    = filetime,
                        version     = version,
                        subfonts    = subfonts,
                        ttcversion  = ttcversion,
                        nofsubfonts = nofsubfonts,
                    }
                    for i=1,nofsubfonts do
                        subfonts[i] = readdata(f,offsets[i],specification)
                    end
                end
            end
        else
            report("unknown version %a in file %a",version,filename)
        end
        closefile(f)
        return fontdata or { }
    end
end

local function loadfont(specification,n)
    if type(specification) == "string" then
        specification = {
            filename    = specification,
            info        = true, -- always true (for now)
            details     = true,
            glyphs      = true,
            shapes      = true,
            kerns       = true,
            globalkerns = true,
            lookups     = true,
            -- true or number:
            subfont     = n or true,
            tounicode   = false,
        }
    end
    -- if shapes only then
    if specification.shapes or specification.lookups or specification.kerns then
        specification.glyphs = true
    end
    if specification.glyphs then
        specification.details = true
    end
    if specification.details then
        specification.info = true -- not really used any more
    end
    if specification.platformnames then
        specification.platformnames = true -- not really used any more
    end
    local function message(str)
        report("fatal error in file %a: %s\n%s",specification.filename,str,debug.traceback())
    end
    local ok, result = xpcall(loadfontdata,message,specification)
    if ok then
        return result
    end
end

-- we need even less, but we can have a 'detail' variant

function readers.loadshapes(filename,n)
    local fontdata = loadfont {
        filename = filename,
        shapes   = true,
        subfont  = n,
    }
    if fontdata then
        -- easier on luajit but still we can hit the 64 K stack constants issue
        for k, v in next, fontdata.glyphs do
            v.class = nil
            v.index = nil
            v.math  = nil
         -- v.name  = nil
        end
    end
    return fontdata and {
     -- version  = 0.123 -- todo
        filename = filename,
        format   = fontdata.format,
        glyphs   = fontdata.glyphs,
        units    = fontdata.fontheader.units,
    } or {
        filename = filename,
        format   = "unknown",
        glyphs   = { },
        units    = 0,
    }
end

function readers.loadfont(filename,n)
    local fontdata = loadfont {
        filename    = filename,
        glyphs      = true,
        shapes      = false,
        lookups     = true,
     -- kerns       = true,
     -- globalkerns = true, -- only for testing, e.g. cambria has different gpos and kern
        subfont     = n,
    }
    if fontdata then
        --
        return {
            tableversion  = tableversion,
            creator       = "context mkiv",
            size          = fontdata.filesize,
            time          = fontdata.filetime,
            glyphs        = fontdata.glyphs,
            descriptions  = fontdata.descriptions,
            format        = fontdata.format,
            goodies       = { },
            metadata      = getinfo(fontdata,n,false,false,true), -- no platformnames here !
            properties    = {
                hasitalics    = fontdata.hasitalics or false,
                maxcolorclass = fontdata.maxcolorclass,
                hascolor      = fontdata.hascolor or false,
            },
            resources     = {
             -- filename      = fontdata.filename,
                filename      = filename,
                private       = privateoffset,
                duplicates    = fontdata.duplicates  or { },
                features      = fontdata.features    or { }, -- we need to add these in the loader
                sublookups    = fontdata.sublookups  or { }, -- we need to add these in the loader
                marks         = fontdata.marks       or { }, -- we need to add these in the loader
                markclasses   = fontdata.markclasses or { }, -- we need to add these in the loader
                marksets      = fontdata.marksets    or { }, -- we need to add these in the loader
                sequences     = fontdata.sequences   or { }, -- we need to add these in the loader
                variants      = fontdata.variants, -- variant -> unicode -> glyph
                version       = getname(fontdata,"version"),
                cidinfo       = fontdata.cidinfo,
                mathconstants = fontdata.mathconstants,
                colorpalettes = fontdata.colorpalettes,
                svgshapes     = fontdata.svgshapes,
            },
        }
    end
end

function readers.getinfo(filename,specification) -- string, nil|number|table
    -- platformnames is optional and not used by context (a too unpredictable mess
    -- that only add to the confusion) .. so it's only for checking things
    local subfont        = nil
    local platformnames  = false
    local rawfamilynames = false
    if type(specification) == "table" then
        subfont        = tonumber(specification.subfont)
        platformnames  = specification.platformnames
        rawfamilynames = specification.rawfamilynames
    else
        subfont       = tonumber(specification)
    end
    local fontdata = loadfont {
        filename       = filename,
        details        = true,
        platformnames  = platformnames,
     -- rawfamilynames = rawfamilynames,
    }
    if fontdata then
        local subfonts = fontdata.subfonts
        if not subfonts then
            return getinfo(fontdata,nil,platformnames,rawfamilynames)
        elseif not subfont then
            local info = { }
            for i=1,#subfonts do
                info[i] = getinfo(fontdata,i,platformnames,rawfamilynames)
            end
            return info
        elseif subfont >= 1 and subfont <= #subfonts then
            return getinfo(fontdata,subfont,platformnames,rawfamilynames)
        else
            return {
                filename = filename,
                comment  = "there is no subfont " .. subfont .. " in this file"
            }
        end
    else
        return {
            filename = filename,
            comment  = "the file cannot be opened for reading",
        }
    end
end

function readers.rehash(fontdata,hashmethod)
    report("the %a helper is not yet implemented","rehash")
end

function readers.checkhash(fontdata)
    report("the %a helper is not yet implemented","checkhash")
end

function readers.pack(fontdata,hashmethod)
    report("the %a helper is not yet implemented","pack")
end

function readers.unpack(fontdata)
    report("the %a helper is not yet implemented","unpack")
end

function readers.expand(fontdata)
    report("the %a helper is not yet implemented","unpack")
end

function readers.compact(fontdata)
    report("the %a helper is not yet implemented","compact")
end

-- plug in

local extenders = { }

function readers.registerextender(extender)
    extenders[#extenders+1] = extender
end

function readers.extend(fontdata)
    for i=1,#extenders do
        local extender = extenders[i]
        local name     = extender.name or "unknown"
        local action   = extender.action
        if action then
            action(fontdata)
        end
    end
end