summaryrefslogtreecommitdiff
path: root/Build/source/texk/web2c/omegaware/ovf2ovp.web
blob: 2e2e374dca5bbe8fa29a7d97407933aa291c5a22 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054
2055
2056
2057
2058
2059
2060
2061
2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095
2096
2097
2098
2099
2100
2101
2102
2103
2104
2105
2106
2107
2108
2109
2110
2111
2112
2113
2114
2115
2116
2117
2118
2119
2120
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
2133
2134
2135
2136
2137
2138
2139
2140
2141
2142
2143
2144
2145
2146
2147
2148
2149
2150
2151
2152
2153
2154
2155
2156
2157
2158
2159
2160
2161
2162
2163
2164
2165
2166
2167
2168
2169
2170
2171
2172
2173
2174
2175
2176
2177
2178
2179
2180
2181
2182
2183
2184
2185
2186
2187
2188
2189
2190
2191
2192
2193
2194
2195
2196
2197
2198
2199
2200
2201
2202
2203
2204
2205
2206
2207
2208
2209
2210
2211
2212
2213
2214
2215
2216
2217
2218
2219
2220
2221
2222
2223
2224
2225
2226
2227
2228
2229
2230
2231
2232
2233
2234
2235
2236
2237
2238
2239
2240
2241
2242
2243
2244
2245
2246
2247
2248
2249
2250
2251
2252
2253
2254
2255
2256
2257
2258
2259
2260
2261
2262
2263
2264
2265
2266
2267
2268
2269
2270
2271
2272
2273
2274
2275
2276
2277
2278
2279
2280
2281
2282
2283
2284
2285
2286
2287
2288
2289
2290
2291
2292
2293
2294
2295
2296
2297
2298
2299
2300
2301
2302
2303
2304
2305
2306
2307
2308
2309
2310
2311
2312
2313
2314
2315
2316
2317
2318
2319
2320
2321
2322
2323
2324
2325
2326
2327
2328
2329
2330
2331
2332
2333
2334
2335
2336
2337
2338
2339
2340
2341
2342
2343
2344
2345
2346
2347
2348
2349
2350
2351
2352
2353
2354
2355
2356
2357
2358
2359
2360
2361
2362
2363
2364
2365
2366
2367
2368
2369
2370
2371
2372
2373
2374
2375
2376
2377
2378
2379
2380
2381
2382
2383
2384
2385
2386
2387
2388
2389
2390
2391
2392
2393
2394
2395
2396
2397
2398
2399
2400
2401
2402
2403
2404
2405
2406
2407
2408
2409
2410
2411
2412
2413
2414
2415
2416
2417
2418
2419
2420
2421
2422
2423
2424
2425
2426
2427
2428
2429
2430
2431
2432
2433
2434
2435
2436
2437
2438
2439
2440
2441
2442
2443
2444
2445
2446
2447
2448
2449
2450
2451
2452
2453
2454
2455
2456
2457
2458
2459
2460
2461
2462
2463
2464
2465
2466
2467
2468
2469
2470
2471
2472
2473
2474
2475
2476
2477
2478
2479
2480
2481
2482
2483
2484
2485
2486
2487
2488
2489
2490
2491
2492
2493
2494
2495
2496
2497
2498
2499
2500
2501
2502
2503
2504
2505
2506
2507
2508
2509
2510
2511
2512
2513
2514
2515
2516
2517
2518
2519
2520
2521
2522
2523
2524
2525
2526
2527
2528
2529
2530
2531
2532
2533
2534
2535
2536
2537
2538
2539
2540
2541
2542
2543
2544
2545
2546
2547
2548
2549
2550
2551
2552
2553
2554
2555
2556
2557
2558
2559
2560
2561
2562
2563
2564
2565
2566
2567
2568
2569
2570
2571
2572
2573
2574
2575
2576
2577
2578
2579
2580
2581
2582
2583
2584
2585
2586
2587
2588
2589
2590
2591
2592
2593
2594
2595
2596
2597
2598
2599
2600
2601
2602
2603
2604
2605
2606
2607
2608
2609
2610
2611
2612
2613
2614
2615
2616
2617
2618
2619
2620
2621
2622
2623
2624
2625
2626
2627
2628
2629
2630
2631
2632
2633
2634
2635
2636
2637
2638
2639
2640
2641
2642
2643
2644
2645
2646
2647
2648
2649
2650
2651
2652
2653
2654
2655
2656
2657
2658
2659
2660
2661
2662
2663
2664
2665
2666
2667
2668
2669
2670
2671
2672
2673
2674
2675
2676
2677
2678
2679
2680
2681
2682
2683
2684
2685
2686
2687
2688
2689
2690
2691
2692
2693
2694
2695
2696
2697
2698
2699
2700
2701
2702
2703
2704
2705
2706
2707
2708
2709
2710
2711
2712
2713
2714
2715
2716
2717
2718
2719
2720
2721
2722
2723
2724
2725
2726
2727
2728
2729
2730
2731
2732
2733
2734
2735
2736
2737
2738
2739
2740
2741
2742
2743
2744
2745
2746
2747
2748
2749
2750
2751
2752
2753
2754
2755
2756
2757
2758
2759
2760
2761
2762
2763
2764
2765
2766
2767
2768
2769
2770
2771
2772
2773
2774
2775
2776
2777
2778
2779
2780
2781
2782
2783
2784
2785
2786
2787
2788
2789
2790
2791
2792
2793
2794
2795
2796
2797
2798
2799
2800
2801
2802
2803
2804
2805
2806
2807
2808
2809
2810
2811
2812
2813
2814
2815
2816
2817
2818
2819
2820
2821
2822
2823
2824
2825
2826
2827
2828
2829
2830
2831
2832
2833
2834
2835
2836
2837
2838
2839
2840
2841
2842
2843
2844
2845
2846
2847
2848
2849
2850
2851
2852
2853
2854
2855
2856
2857
2858
2859
2860
2861
2862
2863
2864
2865
2866
2867
2868
2869
2870
2871
2872
2873
2874
2875
2876
2877
2878
2879
2880
2881
2882
2883
2884
2885
2886
2887
2888
2889
2890
2891
2892
2893
2894
2895
2896
2897
2898
2899
2900
2901
2902
2903
2904
2905
2906
2907
2908
2909
2910
2911
2912
2913
2914
2915
2916
2917
2918
2919
2920
2921
2922
2923
2924
2925
2926
2927
2928
2929
2930
2931
2932
2933
2934
2935
2936
2937
2938
2939
2940
2941
2942
2943
2944
2945
2946
2947
2948
2949
2950
2951
2952
2953
2954
2955
2956
2957
2958
2959
2960
2961
2962
2963
2964
2965
2966
2967
2968
2969
2970
2971
2972
2973
2974
2975
2976
2977
2978
2979
2980
2981
2982
2983
2984
2985
2986
2987
2988
2989
2990
2991
2992
2993
2994
2995
2996
2997
2998
2999
3000
3001
3002
3003
3004
3005
3006
3007
3008
3009
3010
3011
3012
3013
3014
3015
3016
3017
3018
3019
3020
3021
3022
3023
3024
3025
3026
3027
3028
3029
3030
3031
3032
3033
3034
3035
3036
3037
3038
3039
3040
3041
3042
3043
3044
3045
3046
3047
3048
3049
3050
3051
3052
3053
3054
3055
3056
3057
3058
3059
3060
3061
3062
3063
3064
3065
3066
3067
3068
3069
3070
3071
3072
3073
3074
3075
3076
3077
3078
3079
3080
3081
3082
3083
3084
3085
3086
3087
3088
3089
3090
3091
3092
3093
3094
3095
3096
3097
3098
3099
3100
3101
3102
3103
3104
3105
3106
3107
3108
3109
3110
3111
3112
3113
3114
3115
3116
3117
3118
3119
3120
3121
3122
3123
3124
3125
3126
3127
3128
3129
3130
3131
3132
3133
3134
3135
3136
3137
3138
% 
% This file is part of the Omega project, which
% is based in the web2c distribution of TeX.
%
% Copyright (c) 1994--2000 John Plaice and Yannis Haralambous
% applies only to the changes to the original vftovp.web.
%
% This program by D. E. Knuth is not copyrighted and can be used freely.
% Version 1 was implemented in December 1989.
% Version 1.1 fixed problems of strict Pascal (April 1990).
% Version 1.2 fixed various bugs found by Peter Breitenlohner (September 1990).

% Here is TeX material that gets inserted after \input webmac
\def\hang{\hangindent 3em\indent\ignorespaces}
\font\ninerm=cmr9
\let\mc=\ninerm % medium caps for names like SAIL
\def\PASCAL{Pascal}

\def\(#1){} % this is used to make section names sort themselves better
\def\9#1{} % this is used for sort keys in the index

\def\title{OVF2OVP}
\def\contentspagenumber{101}
\def\topofcontents{\null
  \def\titlepage{F} % include headline on the contents page
  \def\rheader{\mainfont\hfil \contentspagenumber}
  \vfill
  \centerline{\titlefont The {\ttitlefont OVF2OVP} processor}
  \vskip 15pt
  \centerline{(Version 1.11, February 2000)}
  \vfill}
\def\botofcontents{\vfill
  \centerline{\hsize 5in\baselineskip9pt
    \vbox{\ninerm\noindent
    The preparation of this program
    was supported in part by the National Science
    Foundation and by the System Development Foundation. `\TeX' is a
    trademark of the American Mathematical Society.}}}
\pageno=\contentspagenumber \advance\pageno by 1

@* Introduction.
The \.{VFtoVP} utility program converts a virtual font (``\.{VF}'') file
and its associated \TeX\ font metric (``\.{TFM}'')
file into an equivalent virtual-property-list (``\.{VPL}'') file. It also
makes a thorough check of the given files, using algorithms that are
essentially the same as those used by
\.{DVI} device drivers and by \TeX. Thus if \TeX\ or a \.{DVI} driver
complains that a \.{TFM} or \.{VF}
file is ``bad,'' this program will pinpoint the source or sources of
badness. A \.{VPL} file output by this program can be edited with
a normal text editor, and the result can be converted back to \.{VF} and \.{TFM}
format using the companion program \.{VPtoVF}.

\indent\.{VFtoVP} is an extended version of the program \.{TFtoPL}, which
is part of the standard \TeX ware library.
The idea of a virtual font was inspired by the work of David R. Fuchs
@^Fuchs, David Raymond@>
who designed a similar set of conventions in 1984 while developing a
device driver for ArborText, Inc. He wrote a somewhat similar program
called \.{AMFtoXPL}.

The |banner| string defined here should be changed whenever \.{VFtoVP}
gets modified.

@d banner=='This is OVF2OVP, Version 1.11' {printed when the program starts}

@ This program is written entirely in standard \PASCAL, except that
it occasionally has lower case letters in strings that are output.
Such letters can be converted to upper case if necessary. The input is read
from |vf_file| and |tfm_file|; the output is written on |vpl_file|.
Error messages and
other remarks are written on the |output| file, which the user may
choose to assign to the terminal if the system permits it.
@^system dependencies@>

The term |print| is used instead of |write| when this program writes on
the |output| file, so that all such output can be easily deflected.

@d print(#)==write(#)
@d print_ln(#)==write_ln(#)

@p program OVF2OVP(@!vf_file,@!tfm_file,@!vpl_file,@!output);
label @<Labels in the outer block@>@/
const @<Constants in the outer block@>@/
type @<Types in the outer block@>@/
var @<Globals in the outer block@>@/
procedure initialize; {this procedure gets things started properly}
  var @!k:integer; {all-purpose index for initialization}
  begin print_ln(banner);@/
  @<Set initial values@>@/
  end;

@ If the program has to stop prematurely, it goes to the
`|final_end|'.

@d final_end=9999 {label for the end of it all}

@<Labels...@>=final_end;

@ The following parameters can be changed at compile time to extend or
reduce \.{VFtoVP}'s capacity.

@<Constants...@>=
@!tfm_size=2000000; {maximum length of |tfm| data, in bytes}
@!vf_size=600000; {maximum length of |vf| data, in bytes}
@!max_fonts=300; {maximum number of local fonts in the |vf| file}
@!lig_size=800000; {maximum length of |lig_kern| program, in words}
@!hash_size=130003; {preferably a prime number, a bit larger than the number
  of character pairs in lig/kern steps}
@!hash_mult=16007; {another prime}
@!max_char=65535; {the largest character number in a font}
@!xmax_char=65536; {|max_char|+1}
@!xxmax_char=65537;{|max_char|+2}
@!xmax_label=80001;{must be greater than |max_lig_steps|}
@!mem_size=40008; {|max_char|*4+8}
@!name_length=50; {a file name shouldn't be longer than this}
@!max_stack=50; {maximum depth of \.{DVI} stack in character packets}

@ Here are some macros for common programming idioms.

@d incr(#) == #:=#+1 {increase a variable by unity}
@d decr(#) == #:=#-1 {decrease a variable by unity}
@d do_nothing == {empty statement}
@d exit=10 {go here to leave a procedure}
@d not_found=45 {go here when you've found nothing}
@d return==goto exit {terminate a procedure call}
@f return==nil

@<Types...@>=
@!byte=0..255; {unsigned eight-bit quantity}

@* Virtual fonts.  The idea behind \.{VF} files is that a general
interface mechanism is needed to switch between the myriad font
layouts provided by different suppliers of typesetting equipment.
Without such a mechanism, people must go to great lengths writing
inscrutable macros whenever they want to use typesetting conventions
based on one font layout in connection with actual fonts that have
another layout. This puts an extra burden on the typesetting system,
interfering with the other things it needs to do (like kerning,
hyphenation, and ligature formation).

These difficulties go away when we have a ``virtual font,''
i.e., a font that exists in a logical sense but not a physical sense.
A typesetting system like \TeX\ can do its job without knowing where the
actual characters come from; a device driver can then do its job by
letting a \.{VF} file tell what actual characters correspond to the
characters \TeX\ imagined were present. The actual characters
can be shifted and/or magnified and/or combined with other characters
from many different fonts. A virtual font can even make use of characters
from virtual fonts, including itself.

Virtual fonts also allow convenient character substitutions for proofreading
purposes, when fonts designed for one output device are unavailable on another.

@ A \.{VF} file is organized as a stream of 8-bit bytes, using conventions
borrowed from \.{DVI} and \.{PK} files. Thus, a device driver that knows
about \.{DVI} and \.{PK} format will already
contain most of the mechanisms necessary to process \.{VF} files. 
We shall assume that \.{DVI} format is understood; the conventions in the
\.{DVI} documentation (see, for example, {\sl \TeX: The Program}, part 31)
are adopted here to define \.{VF} format.

A preamble
appears at the beginning, followed by a sequence of character definitions,
followed by a postamble. More precisely, the first byte of every \.{VF} file
must be the first byte of the following ``preamble command'':

\yskip\hang|pre| 247 |i[1]| |k[1]| |x[k]| |cs[4]| |ds[4]|.
Here |i| is the identification byte of \.{VF}, currently 202. The string
|x| is merely a comment, usually indicating the source of the \.{VF} file.
Parameters |cs| and |ds| are respectively the check sum and the design size
of the virtual font; they should match the first two words in the header of
the \.{TFM} file, as described below.

\yskip
After the |pre| command, the preamble continues with font definitions;
every font needed to specify ``actual'' characters in later
\\{set\_char} commands is defined here. The font definitions are
exactly the same in \.{VF} files as they are in \.{DVI} files, except
that the scaled size |s| is relative and the design size |d| is absolute:

\yskip\hang|fnt_def1| 243 |k[1]| |c[4]| |s[4]| |d[4]| |a[1]| |l[1]| |n[a+l]|.
Define font |k|, where |0<=k<256|.

\yskip\hang|@!fnt_def2| 244 |k[2]| |c[4]| |s[4]| |d[4]| |a[1]| |l[1]| |n[a+l]|.
Define font |k|, where |0<=k<65536|.

\yskip\hang|@!fnt_def3| 245 |k[3]| |c[4]| |s[4]| |d[4]| |a[1]| |l[1]| |n[a+l]|.
Define font |k|, where |0<=k<@t$2^{24}$@>|.

\yskip\hang|@!fnt_def4| 246 |k[4]| |c[4]| |s[4]| |d[4]| |a[1]| |l[1]| |n[a+l]|.
Define font |k|, where |@t$-2^{31}$@><=k<@t$2^{31}$@>|.

\yskip\noindent
These font numbers |k| are ``local''; they have no relation to font numbers
defined in the \.{DVI} file that uses this virtual font. The dimension~|s|,
which represents the scaled size of the local font being defined,
is a |fix_word| relative to the design size of the virtual font.
Thus if the local font is to be used at the same size
as the design size of the virtual font itself, |s| will be the
integer value $2^{20}$. The value of |s| must be positive and less than
$2^{24}$ (thus less than 16 when considered as a |fix_word|). 
The dimension~|d| is a |fix_word| in units of printer's points; hence it
is identical to the design size found in the corresponding \.{TFM} file.

@d id_byte=202

@<Glob...@>=
@!vf_file:packed file of byte;

@ The preamble is followed by zero or more character packets, where each
character packet begins with a byte that is $<243$. Character packets have
two formats, one long and one short:

\yskip\hang|long_char| 242 |pl[4]| |cc[4]| |tfm[4]| |dvi[pl]|. This long form
specifies a virtual character in the general case.

\yskip\hang|short_char0..short_char241|
|pl[1]| |cc[1]| |tfm[3]| |dvi[pl]|. This short form specifies a
virtual character in the common case
when |0<=pl<242| and |0<=cc<256| and $0\le|tfm|<2^{24}$.

\yskip\noindent
Here |pl| denotes the packet length following the |tfm| value; |cc| is
the character code; and |tfm| is the character width copied from the
\.{TFM} file for this virtual font. There should be at most one character
packet having any given |cc| code.

The |dvi| bytes are a sequence of complete \.{DVI} commands, properly
nested with respect to |push| and |pop|. All \.{DVI} operations are
permitted except |bop|, |eop|, and commands with opcodes |>=243|.
Font selection commands (|fnt_num0| through |fnt4|) must refer to fonts
defined in the preamble.

Dimensions that appear in the \.{DVI} instructions are analogous to
|fix_word| quantities; i.e., they are integer multiples of $2^{-20}$ times
the design size of the virtual font. For example, if the virtual font
has design size $10\,$pt, the \.{DVI} command to move down $5\,$pt
would be a \\{down} instruction with parameter $2^{19}$. The virtual font
itself might be used at a different size, say $12\,$pt; then that
\\{down} instruction would move down $6\,$pt instead. Each dimension
must be less than $2^{24}$ in absolute value.

Device drivers processing \.{VF} files treat the sequences of |dvi| bytes
as subroutines or macros, implicitly enclosing them with |push| and |pop|.
Each subroutine begins with |w=x=y=z=0|, and with current font~|f| the
number of the first-defined in the preamble (undefined if there's no
such font). After the |dvi| commands have been
performed, the |h| and~|v| position registers of \.{DVI} format and the
current font~|f| are restored to their former values;
then, if the subroutine has been invoked by a \\{set\_char} or \\{set}
command, |h|~is increased by the \.{TFM} width
(properly scaled)---just as if a simple character had been typeset.

@d long_char=242 {\.{VF} command for general character packet}
@d set_char_0=0 {\.{DVI} command to typeset character 0 and move right}
@d set1=128 {typeset a character and move right}
@d set_rule=132 {typeset a rule and move right}
@d put1=133 {typeset a character}
@d put_rule=137 {typeset a rule}
@d nop=138 {no operation}
@d push=141 {save the current positions}
@d pop=142 {restore previous positions}
@d right1=143 {move right}
@d w0=147 {move right by |w|}
@d w1=148 {move right and set |w|}
@d x0=152 {move right by |x|}
@d x1=153 {move right and set |x|}
@d down1=157 {move down}
@d y0=161 {move down by |y|}
@d y1=162 {move down and set |y|}
@d z0=166 {move down by |z|}
@d z1=167 {move down and set |z|}
@d fnt_num_0=171 {set current font to 0}
@d fnt1=235 {set current font}
@d xxx1=239 {extension to \.{DVI} primitives}
@d xxx4=242 {potentially long extension to \.{DVI} primitives}
@d fnt_def1=243 {define the meaning of a font number}
@d pre=247 {preamble}
@d post=248 {postamble beginning}
@d improper_DVI_for_VF==139,140,243,244,245,246,247,248,249,250,251,252,
    253,254,255

@ The character packets are followed by a trivial postamble, consisting of
one or more bytes all equal to |post| (248). The total number of bytes
in the file should be a multiple of~4.

@* Font metric data.
The idea behind \.{TFM} files is that typesetting routines like \TeX\
need a compact way to store the relevant information about several
dozen fonts, and computer centers need a compact way to store the
relevant information about several hundred fonts. \.{TFM} files are
compact, and most of the information they contain is highly relevant,
so they provide a solution to the problem.

The information in a \.{TFM} file appears in a sequence of 8-bit bytes.
Since the number of bytes is always a multiple of 4, we could
also regard the file as a sequence of 32-bit words; but \TeX\ uses the
byte interpretation, and so does \.{VFtoVP}. Note that the bytes
are considered to be unsigned numbers.

@<Glob...@>=
@!tfm_file:packed file of byte;

@ On some systems you may have to do something special to read a
packed file of bytes. For example, the following code didn't work
when it was first tried at Stanford, because packed files have to be
opened with a special switch setting on the \PASCAL\ that was used.
@^system dependencies@>

@<Set init...@>=
reset(tfm_file); reset(vf_file);

@ The first 24 bytes (6 words) of a \.{TFM} file contain twelve 16-bit
integers that give the lengths of the various subsequent portions
of the file. These twelve integers are, in order:
$$\vbox{\halign{\hfil#&$\null=\null$#\hfil\cr
|@!lf|&length of the entire file, in words;\cr
|@!lh|&length of the header data, in words;\cr
|@!bc|&smallest character code in the font;\cr
|@!ec|&largest character code in the font;\cr
|@!nw|&number of words in the width table;\cr
|@!nh|&number of words in the height table;\cr
|@!nd|&number of words in the depth table;\cr
|@!ni|&number of words in the italic correction table;\cr
|@!nl|&number of words in the lig/kern table;\cr
|@!nk|&number of words in the kern table;\cr
|@!ne|&number of words in the extensible character table;\cr
|@!np|&number of font parameter words.\cr}}$$
They are all nonnegative and less than $2^{15}$. We must have |bc-1<=ec<=255|,
|ne<=256|, and
$$\hbox{|lf=6+lh+(ec-bc+1)+nw+nh+nd+ni+nl+nk+ne+np|.}$$
Note that a font may contain as many as 256 characters (if |bc=0| and |ec=255|),
and as few as 0 characters (if |bc=ec+1|).

Incidentally, when two or more 8-bit bytes are combined to form an integer of
16 or more bits, the most significant bytes appear first in the file.
This is called BigEndian order.

@<Glob...@>=
@!ofm_level,
@!nco,@!ncw,@!npc,@!nki,@!nwi,@!nkf,@!nwf,@!nkr,@!nwr,@!nkg,@!nwg,@!nkp,@!nwp,
@!nkm,@!nwm,@!real_lf,
@!lf,@!lh,@!bc,@!ec,@!nw,@!nh,@!nd,@!ni,@!nl,@!nk,@!ne,@!np,@!font_dir:integer;
  {subfile sizes}
@!ofm_on:boolean;

@ @<Set init...@>=
ofm_on:=false; ofm_level:=-1; lf:=0; lh:=0;
nco:=0; ncw:=0; npc:=0; bc:=0; ec:=0; nw:=0; nh:=0; nd:=0; ni:=0;
nl:=0; nk:=0; ne:=0; np:=0;
nki:=0; nwi:=0; nkf:=0; nwf:=0;
nkm:=0; nwm:=0; real_lf:=0;
nkr:=0; nwr:=0; nkg:=0; nwg:=0;
nkp:=0; nwp:=0; font_dir:=0;

@ The rest of the \.{TFM} file may be regarded as a sequence of ten data
arrays having the informal specification
$$\def\arr$[#1]#2${\&{array} $[#1]$ \&{of} #2}
\vbox{\halign{\hfil\\{#}&$\,:\,$\arr#\hfil\cr
header&|[0..lh-1]stuff|\cr
char\_info&|[bc..ec]char_info_word|\cr
width&|[0..nw-1]fix_word|\cr
height&|[0..nh-1]fix_word|\cr
depth&|[0..nd-1]fix_word|\cr
italic&|[0..ni-1]fix_word|\cr
lig\_kern&|[0..nl-1]lig_kern_command|\cr
kern&|[0..nk-1]fix_word|\cr
exten&|[0..ne-1]extensible_recipe|\cr
param&|[1..np]fix_word|\cr}}$$
The most important data type used here is a |@!fix_word|, which is
a 32-bit representation of a binary fraction. A |fix_word| is a signed
quantity, with the two's complement of the entire word used to represent
negation. Of the 32 bits in a |fix_word|, exactly 12 are to the left of the
binary point; thus, the largest |fix_word| value is $2048-2^{-20}$, and
the smallest is $-2048$. We will see below, however, that all but one of
the |fix_word| values will lie between $-16$ and $+16$.

@ The first data array is a block of header information, which contains
general facts about the font. The header must contain at least two words,
and for \.{TFM} files to be used with Xerox printing software it must
contain at least 18 words, allocated as described below. When different
kinds of devices need to be interfaced, it may be necessary to add further
words to the header block.

\yskip\hang|header[0]| is a 32-bit check sum that \TeX\ will copy into the
\.{DVI} output file whenever it uses the font.  Later on when the \.{DVI}
file is printed, possibly on another computer, the actual font that gets
used is supposed to have a check sum that agrees with the one in the
\.{TFM} file used by \TeX. In this way, users will be warned about
potential incompatibilities. (However, if the check sum is zero in either
the font file or the \.{TFM} file, no check is made.)  The actual relation
between this check sum and the rest of the \.{TFM} file is not important;
the check sum is simply an identification number with the property that
incompatible fonts almost always have distinct check sums.
@^check sum@>

\yskip\hang|header[1]| is a |fix_word| containing the design size of the
font, in units of \TeX\ points (7227 \TeX\ points = 254 cm).  This number
must be at least 1.0; it is fairly arbitrary, but usually the design size
is 10.0 for a ``10 point'' font, i.e., a font that was designed to look
best at a 10-point size, whatever that really means. When a \TeX\ user
asks for a font `\.{at} $\delta$ \.{pt}', the effect is to override the
design size and replace it by $\delta$, and to multiply the $x$ and~$y$
coordinates of the points in the font image by a factor of $\delta$
divided by the design size.  {\sl All other dimensions in the\/\ \.{TFM}
file are |fix_word|\kern-1pt\ numbers in design-size units.} Thus, for example,
the value of |param[6]|, one \.{em} or \.{\\quad}, is often the |fix_word|
value $2^{20}=1.0$, since many fonts have a design size equal to one em.
The other dimensions must be less than 16 design-size units in absolute
value; thus, |header[1]| and |param[1]| are the only |fix_word| entries in
the whole \.{TFM} file whose first byte might be something besides 0 or
255.  @^design size@>

\yskip\hang|header[2..11]|, if present, contains 40 bytes that identify
the character coding scheme. The first byte, which must be between 0 and
39, is the number of subsequent ASCII bytes actually relevant in this
string, which is intended to specify what character-code-to-symbol
convention is present in the font.  Examples are \.{ASCII} for standard
ASCII, \.{TeX text} for fonts like \.{cmr10} and \.{cmti9}, \.{TeX math
extension} for \.{cmex10}, \.{XEROX text} for Xerox fonts, \.{GRAPHIC} for
special-purpose non-alphabetic fonts, \.{UNSPECIFIED} for the default case
when there is no information.  Parentheses should not appear in this name.
(Such a string is said to be in {\mc BCPL} format.)
@^coding scheme@>

\yskip\hang|header[12..16]|, if present, contains 20 bytes that name the
font family (e.g., \.{CMR} or \.{HELVETICA}), in {\mc BCPL} format.
This field is also known as the ``font identifier.''
@^family name@>
@^font identifier@>

\yskip\hang|header[17]|, if present, contains a first byte called the
|seven_bit_safe_flag|, then two bytes that are ignored, and a fourth byte
called the |face|. If the value of the fourth byte is less than 18, it has
the following interpretation as a ``weight, slope, and expansion'':  Add 0
or 2 or 4 (for medium or bold or light) to 0 or 1 (for roman or italic) to
0 or 6 or 12 (for regular or condensed or extended).  For example, 13 is
0+1+12, so it represents medium italic extended.  A three-letter code
(e.g., \.{MIE}) can be used for such |face| data.

\yskip\hang|header[18..@twhatever@>]| might also be present; the individual
words are simply called |header[18]|, |header[19]|, etc., at the moment.

@ Next comes the |char_info| array, which contains one |char_info_word|
per character. Each |char_info_word| contains six fields packed into
four bytes as follows.

\yskip\hang first byte: |width_index| (8 bits)\par
\hang second byte: |height_index| (4 bits) times 16, plus |depth_index|
  (4~bits)\par
\hang third byte: |italic_index| (6 bits) times 4, plus |tag|
  (2~bits)\par
\hang fourth byte: |remainder| (8 bits)\par
\yskip\noindent
The actual width of a character is |width[width_index]|, in design-size
units; this is a device for compressing information, since many characters
have the same width. Since it is quite common for many characters
to have the same height, depth, or italic correction, the \.{TFM} format
imposes a limit of 16 different heights, 16 different depths, and
64 different italic corrections.

Incidentally, the relation |width[0]=height[0]=depth[0]=italic[0]=0|
should always hold, so that an index of zero implies a value of zero.
The |width_index| should never be zero unless the character does
not exist in the font, since a character is valid if and only if it lies
between |bc| and |ec| and has a nonzero |width_index|.

@ The |tag| field in a |char_info_word| has four values that explain how to
interpret the |remainder| field.

\yskip\hang|tag=0| (|no_tag|) means that |remainder| is unused.\par
\hang|tag=1| (|lig_tag|) means that this character has a ligature/kerning
program starting at |lig_kern[remainder]|.\par
\hang|tag=2| (|list_tag|) means that this character is part of a chain of
characters of ascending sizes, and not the largest in the chain.  The
|remainder| field gives the character code of the next larger character.\par
\hang|tag=3| (|ext_tag|) means that this character code represents an
extensible character, i.e., a character that is built up of smaller pieces
so that it can be made arbitrarily large. The pieces are specified in
|exten[remainder]|.\par

@d no_tag=0 {vanilla character}
@d lig_tag=1 {character has a ligature/kerning program}
@d list_tag=2 {character has a successor in a charlist}
@d ext_tag=3 {character is extensible}

@ The |lig_kern| array contains instructions in a simple programming language
that explains what to do for special letter pairs. Each word is a
|lig_kern_command| of four bytes.

\yskip\hang first byte: |skip_byte|, indicates that this is the final program
  step if the byte is 128 or more, otherwise the next step is obtained by
  skipping this number of intervening steps.\par
\hang second byte: |next_char|, ``if |next_char| follows the current character,
  then perform the operation and stop, otherwise continue.''\par
\hang third byte: |op_byte|, indicates a ligature step if less than~128,
  a kern step otherwise.\par
\hang fourth byte: |remainder|.\par
\yskip\noindent
In a kern step, an
additional space equal to |kern[256*(op_byte-128)+remainder]| is inserted
between the current character and |next_char|. This amount is
often negative, so that the characters are brought closer together
by kerning; but it might be positive.

There are eight kinds of ligature steps, having |op_byte| codes $4a+2b+c$ where
$0\le a\le b+c$ and $0\le b,c\le1$. The character whose code is
|remainder| is inserted between the current character and |next_char|;
then the current character is deleted if $b=0$, and |next_char| is
deleted if $c=0$; then we pass over $a$~characters to reach the next
current character (which may have a ligature/kerning program of its own).

Notice that if $a=0$ and $b=1$, the current character is unchanged; if
$a=b$ and $c=1$, the current character is changed but the next character is
unchanged. \.{VFtoVP} will check to see that infinite loops are avoided.

If the very first instruction of the |lig_kern| array has |skip_byte=255|,
the |next_char| byte is the so-called right boundary character of this font;
the value of |next_char| need not lie between |bc| and~|ec|.
If the very last instruction of the |lig_kern| array has |skip_byte=255|,
there is a special ligature/kerning program for a left boundary character,
beginning at location |256*op_byte+remainder|.
The interpretation is that \TeX\ puts implicit boundary characters
before and after each consecutive string of characters from the same font.
These implicit characters do not appear in the output, but they can affect
ligatures and kerning.

If the very first instruction of a character's |lig_kern| program has
|skip_byte>128|, the program actually begins in location
|256*op_byte+remainder|. This feature allows access to large |lig_kern|
arrays, because the first instruction must otherwise
appear in a location |<=255|.

Any instruction with |skip_byte>128| in the |lig_kern| array must have
|256*op_byte+remainder<nl|. If such an instruction is encountered during
normal program execution, it denotes an unconditional halt; no ligature
command is performed.

@d stop_flag=128 {value indicating `\.{STOP}' in a lig/kern program}
@d kern_flag=128 {op code for a kern step}

@ Extensible characters are specified by an |extensible_recipe|,
which consists of four bytes called |top|, |mid|,
|bot|, and |rep| (in this order). These bytes are the character codes
of individual pieces used to build up a large symbol.
If |top|, |mid|, or |bot| are zero,
they are not present in the built-up result. For example, an extensible
vertical line is like an extensible bracket, except that the top and
bottom pieces are missing.


@ The final portion of a \.{TFM} file is the |param| array, which is another
sequence of |fix_word| values.

\yskip\hang|param[1]=@!slant| is the amount of italic slant, which is used
to help position accents. For example, |slant=.25| means that when you go
up one unit, you also go .25 units to the right. The |slant| is a pure
number; it's the only |fix_word| other than the design size itself that is
not scaled by the design size.

\hang|param[2]=space| is the normal spacing between words in text.
Note that character |" "| in the font need not have anything to do with
blank spaces.

\hang|param[3]=space_stretch| is the amount of glue stretching between words.

\hang|param[4]=space_shrink| is the amount of glue shrinking between words.

\hang|param[5]=x_height| is the height of letters for which accents don't
have to be raised or lowered.

\hang|param[6]=quad| is the size of one em in the font.

\hang|param[7]=extra_space| is the amount added to |param[2]| at the
ends of sentences.

When the character coding scheme is \.{TeX math symbols}, the font is
supposed to have 15 additional parameters called |num1|, |num2|, |num3|,
|denom1|, |denom2|, |sup1|, |sup2|, |sup3|, |sub1|, |sub2|, |supdrop|,
|subdrop|, |delim1|, |delim2|, and |axis_height|, respectively. When the
character coding scheme is \.{TeX math extension}, the font is supposed to
have six additional parameters called |default_rule_thickness| and
|big_op_spacing1| through |big_op_spacing5|.

@ So that is what \.{TFM} files hold. The next question is, ``What about
\.{VPL} files?'' A complete answer to that question appears in the
documentation of the companion program, \.{VPtoVF}, so it will not
be repeated here. Suffice it to say that a \.{VPL} file is an ordinary
\PASCAL\ text file, and that the output of \.{VFtoVP} uses only a
subset of the possible constructions that might appear in a \.{VPL} file.
Furthermore, hardly anybody really wants to look at the formal
definition of \.{VPL} format, because it is almost self-explanatory when
you see an example or two.

@<Glob...@>=
@!vpl_file:text;

@ @<Set init...@>=
rewrite(vpl_file);

@* Unpacking the TFM file.
The first thing \.{VFtoVP} does is read the entire |tfm_file| into an array of
bytes, |tfm[0..(4*lf-1)]|.

@<Types...@>=
@!index=0..tfm_size; {address of a byte in |tfm|}
@!char_type=0..65535;
@!xchar_type=0..65536;
@!xxchar_type=0..65537;
@!xxxchar_type=0..65538;

@ 
@<Glob...@>=
@!tfm:array [-1000..tfm_size] of byte; {the input data all goes here}
 {the negative addresses avoid range checks for invalid characters}
@!top_char,@!top_width,@!top_height,@!top_depth,@!top_italic:integer;
@!start_ptr,@!check_sum,@!design_size,@!scheme,@!family,@!random_word:integer;
@!header_length,@!char_ptr,@!copies,@!j:integer;

@ The input may, of course, be all screwed up and not a \.{TFM} file
at all. So we begin cautiously.

@d abort(#)==begin print_ln(#);
  print_ln('Sorry, but I can''t go on; are you sure this is a OFM?');
  goto final_end;
  end

@<Read the whole font metric file@>=
read(tfm_file,tfm[0]);
if tfm[0]>127 then abort('The first byte of the input file exceeds 127!');
@.The first byte...@>
if eof(tfm_file) then abort('The input file is only one byte long!');
@.The input...one byte long@>
read(tfm_file,tfm[1]); lf:=tfm[0]*@'400+tfm[1];
if lf=0 then begin
  for i:=2 to 7 do begin
    if eof(tfm_file)
    then abort('The input file is too short to designate its length!');
    read(tfm_file, tfm[i]);
    end;
  ofm_on := true; ofm_level := tfm[2]*@"100+tfm[3];
  if tfm[4]>127 then abort('The fifth byte of the input file exceeds 127!');
  lf := tfm[4]*@"1000000 + tfm[5]*@"10000 + tfm[6]*@"100 + tfm[7];
  end
else begin
  ofm_on := false;
  end;
case ofm_level of
  -1: begin start_ptr:=2; check_sum:=24; end;
  0: begin start_ptr:=8; check_sum:=56; end;
  1: begin start_ptr:=8; check_sum:=116; end;
  end;
design_size:=check_sum+4;
scheme:=design_size+4;
family:=scheme+40;
random_word:=family+20;
if lf=0 then
  abort('The file claims to have length zero, but that''s impossible!');
@.The file claims...@>
if 4*lf-1>tfm_size then abort('The file is bigger than I can handle!');
@.The file is bigger...@>
for tfm_ptr:=start_ptr to 4*lf-1 do begin
  if eof(tfm_file) then
    abort('The file has fewer bytes than it claims!');
@.The file has fewer bytes...@>
  read(tfm_file,tfm[tfm_ptr]);
  end;
if not eof(tfm_file) then begin
  print_ln('There''s some extra junk at the end of the OFM file,');
@.There's some extra junk...@>
  print_ln('but I''ll proceed as if it weren''t there.');
  end

@ After the file has been read successfully, we look at the subfile sizes
to see if they check out.

@d eval_two_bytes(#)==begin if tfm[tfm_ptr]>127 then
    abort('One of the subfile sizes is negative!');
@.One of the subfile sizes...@>
  #:=tfm[tfm_ptr]*@'400+tfm[tfm_ptr+1];
  tfm_ptr:=tfm_ptr+2;
  end
@d eval_four_bytes(#)==begin if tfm[tfm_ptr]>127 then
    abort('One of the subfile sizes is negative!');
@.One of the subfile sizes...@>
  #:=tfm[tfm_ptr]*@"1000000+tfm[tfm_ptr+1]*@"10000+
  tfm[tfm_ptr+2]*@"100+tfm[tfm_ptr+3];
  tfm_ptr:=tfm_ptr+4;
  end

@<Set subfile sizes |lh|, |bc|, \dots, |np|@>=
begin
if not ofm_on then begin
  tfm_ptr:=2;
  eval_two_bytes(lh);
  eval_two_bytes(bc);
  eval_two_bytes(ec);
  eval_two_bytes(nw);
  eval_two_bytes(nh);
  eval_two_bytes(nd);
  eval_two_bytes(ni);
  eval_two_bytes(nl);
  eval_two_bytes(nk);
  eval_two_bytes(ne);
  eval_two_bytes(np);
  ncw:=(ec-bc+1);
  header_length:=6;
  top_char:=255;
  top_width:=255;
  top_height:=15;
  top_depth:=15;
  top_italic:=63;
  end
else begin
  tfm_ptr:=8;
  eval_four_bytes(lh);
  eval_four_bytes(bc);
  eval_four_bytes(ec);
  eval_four_bytes(nw);
  eval_four_bytes(nh);
  eval_four_bytes(nd);     
  eval_four_bytes(ni);
  eval_four_bytes(nl);
  eval_four_bytes(nk);
  eval_four_bytes(ne);
  eval_four_bytes(np);
  eval_four_bytes(font_dir);
  top_char:=65535;
  top_width:=65535;
  top_height:=255;
  top_depth:=255;
  top_italic:=255;
  if ofm_level=0 then begin
    header_length:=14;
    ncw:=2*(ec-bc+1);
    end
  else begin
    header_length:=29;
    eval_four_bytes(nco);
    eval_four_bytes(ncw);
    eval_four_bytes(npc);
    eval_four_bytes(nki); {Kinds of font ivalues}
    eval_four_bytes(nwi); {Words of font ivalues}
    eval_four_bytes(nkf); {Kinds of font fvalues}
    eval_four_bytes(nwf); {Words of font fvalues}
    eval_four_bytes(nkm); {Kinds of font mvalues}
    eval_four_bytes(nwm); {Words of font mvalues}
    eval_four_bytes(nkr); {Kinds of font rules}
    eval_four_bytes(nwr); {Words of font rules}
    eval_four_bytes(nkg); {Kinds of font glues}
    eval_four_bytes(nwg); {Words of font glues}
    eval_four_bytes(nkp); {Kinds of font penalties}
    eval_four_bytes(nwp); {Words of font penalties}
    end;
  end;
if lf<>(header_length+lh+ncw+nw+nh+nd+ni+2*nl+nk+2*ne+np+
        nki+nwi+nkf+nwf+nkr+nwr+nkg+nwg+nkp+nwp) then
  abort('Subfile sizes don''t add up to the stated total!');
@.Subfile sizes don't add up...@>
if lh<2 then abort('The header length is only ',lh:1,'!');
@.The header length...@>
if (2*nl)>(4*lig_size) then
  abort('The lig/kern program is longer than I can handle!');
@.The lig/kern program...@>
if (bc>ec+1)or(ec>top_char) then abort('The character code range ',
@.The character code range...@>
  bc:1,'..',ec:1,'is illegal!');
if ec>max_char then
  abort('Character ',ec:1,'is too large.  Ask a wizard to enlarge me.');
if (nw=0)or(nh=0)or(nd=0)or(ni=0) then
  abort('Incomplete subfiles for character dimensions!');
@.Incomplete subfiles...@>
if ne>(top_char+1) then abort('There are ',ne:1,' extensible recipes!');
@.There are ... recipes@>
end

@ Once the input data successfully passes these basic checks,
\.{TFtoPL} believes that it is a \.{TFM} file, and the conversion
to \.{PL} format will take place. Access to the various subfiles
is facilitated by computing the following base addresses. For example,
the |char_info| for character |c| in a \.{TFM} file will start in location
|4*(char_base+c)| of the |tfm| array.

@<Globals...@>=
@!ivalues_start,@!fvalues_start,@!mvalues_start,
@!rules_start,@!glues_start,@!penalties_start:
integer;
@!ivalues_base,@!fvalues_base,@!mvalues_base,
@!rules_base,@!glues_base,@!penalties_base:
integer;
@!char_base,@!width_base,@!height_base,@!depth_base,@!italic_base: integer;
@!lig_kern_base,@!kern_base,@!exten_base,@!param_base:integer;
  {base addresses for the subfiles}
@!char_start:array [0..max_char] of integer;
@!bytes_per_entry:integer;

@ @<Compute the base addresses@>=
begin 
ivalues_start:=header_length+lh;
fvalues_start:=ivalues_start+nki;
mvalues_start:=fvalues_start+nkf;
rules_start:=mvalues_start+nkm;
glues_start:=rules_start+nkr;
penalties_start:=glues_start+nkg;
ivalues_base:=penalties_start+nkp;
fvalues_base:=ivalues_base+nwi;
mvalues_base:=fvalues_base+nwi;
rules_base:=mvalues_base+nwm;
glues_base:=rules_base+nwr;
penalties_base:=glues_base+nwg;
char_base:=penalties_base+nwp;
bytes_per_entry:=(12 + 2*npc) div 4 * 4;
if not ofm_on then begin
  for i:=bc to ec do begin
    char_start[i]:=4*char_base+4*(i-bc);
    end;
  end
else if ofm_level=0 then begin
  for i:=bc to ec do begin
    char_start[i]:=4*char_base+8*(i-bc);
    end;
  end   
else begin
  char_ptr:=4*char_base;
  i:=bc;
  while i<=ec do begin
    copies:=1+256*tfm[char_ptr+8]+tfm[char_ptr+9];
    for j:=1 to copies do begin
      char_start[i]:=char_ptr;
      i:=i+1;
      end;
    char_ptr:=char_ptr + bytes_per_entry;
    end;
  if char_ptr<>(4*(char_base+ncw)) then
    abort('Length of char info table does not correspond to specification');
  end;
width_base:=char_base+ncw;
height_base:=width_base+nw;
depth_base:=height_base+nh;
italic_base:=depth_base+nd;
lig_kern_base:=italic_base+ni;
kern_base:=lig_kern_base+2*nl;
exten_base:=kern_base+nk;
param_base:=exten_base+2*ne-1;
end

@ Of course we want to define macros that suppress the detail of how the
font information is actually encoded. Each word will be referred to by
the |tfm| index of its first byte. For example, if |c| is a character
code between |bc| and |ec|, then |tfm[char_info(c)]| will be the
first byte of its |char_info|, i.e., the |width_index|; furthermore
|width(c)| will point to the |fix_word| for |c|'s width.

@d char_info(#)==char_start[#]
@d nonexistent(#)==((#<bc)or(#>ec)or(width_index(#)=0))
@d width(#)==4*(width_base+width_index(#))
@d height(#)==4*(height_base+height_index(#))
@d depth(#)==4*(depth_base+depth_index(#))
@d italic(#)==4*(italic_base+italic_index(#))
@d kern(#)==4*(kern_base+#) {here \#\ is an index, not a character}
@d param(#)==4*(param_base+#) {likewise}

@p function width_index(c:char_type):integer;
begin if not ofm_on then
  width_index:=tfm[char_info(c)]
else
  width_index:=256*tfm[char_info(c)]+tfm[char_info(c)+1];
end;

function height_index(c:char_type):integer;
begin if not ofm_on then
  height_index:=tfm[char_info(c)+1] div 16
else
  height_index:=tfm[char_info(c)+2];
end;

function depth_index(c:char_type):integer;
begin if not ofm_on then
  depth_index:=tfm[char_info(c)+1] mod 16
else
  depth_index:=tfm[char_info(c)+3];
end;

function italic_index(c:char_type):integer;
begin if not ofm_on then
  italic_index:=tfm[char_info(c)+2] div 4
else if ofm_level=0 then
  italic_index:=tfm[char_info(c)+4]*64 + tfm[char_info(c)+5] div 4
else
  italic_index:=tfm[char_info(c)+4];
end;

function tag(c:char_type):integer;
begin if not ofm_on then
  tag:=tfm[char_info(c)+2] mod 4
else
  tag:=tfm[char_info(c)+5] mod 4;
end;

procedure set_no_tag(c:char_type);
begin if not ofm_on then
  tfm[char_info(c)+2] := (tfm[char_info(c)+2] div 64)*64 + no_tag
else
  tfm[char_info(c)+5] := (tfm[char_info(c)+5] div 64)*64 + no_tag;
end;

function ctag(c:char_type):boolean;
begin if not (ofm_level=1) then
  ctag:=false
else
  ctag:=tfm[char_info(c)+5] div 4 mod 2;
end;

procedure set_no_ctag(c:char_type);
begin if not (ofm_level=1) then
  tfm[char_info(c)+5] := 
    tfm[char_info(c)+5] div 8 * 8 + tfm[char_info(c)+5] mod 4;
end;

function no_repeats(c:char_type):integer;
begin if ofm_level<=0 then
  no_repeats:=0
else
  no_repeats:=256*tfm[char_info(c)+8]+tfm[char_info(c)+9];
end;

function char_param(c:char_type; i:integer):integer;
begin
  char_param:=256*tfm[char_info(c)+2*i+10]+tfm[char_info(c)+2*i+11];
end;

function rremainder(c:char_type):integer;
begin if not ofm_on then
  rremainder:=tfm[char_info(c)+3]
else
  rremainder:=256*tfm[char_info(c)+6]+tfm[char_info(c)+7];
end;

function lig_step(c:char_type):integer;
begin if not ofm_on then
  lig_step:=4*(lig_kern_base+c)
else
  lig_step:=4*(lig_kern_base+2*c);
end;

function exten(c:char_type):integer;
begin if not ofm_on then
  exten:=4*(exten_base+rremainder(c))
else
  exten:=4*(exten_base+2*rremainder(c));
end;

function l_skip_byte(c:integer):integer;
begin if not ofm_on then
  l_skip_byte:=tfm[c]
else
  l_skip_byte:=256*tfm[c]+tfm[c+1];
end;

procedure set_l_skip_byte(c:integer; newc:integer);
begin if not ofm_on then
  tfm[c]:=newc
else begin
  tfm[c]:=newc div 256;
  tfm[c+1]:=newc mod 256
  end
end;

function l_next_char(c:integer):integer;
begin if not ofm_on then
  l_next_char:=tfm[c+1]
else
  l_next_char:=256*tfm[c+2]+tfm[c+3];
end;

procedure set_l_next_char(c:integer; newc:char_type);
begin if not ofm_on then
  tfm[c+1]:=newc
else begin
  tfm[c+2]:=newc div 256;
  tfm[c+3]:=newc mod 256
  end
end;

function l_op_byte(c:integer):integer;
begin if not ofm_on then
  l_op_byte:=tfm[c+2]
else
  l_op_byte:=256*tfm[c+4]+tfm[c+5];
end;

procedure set_l_op_byte(c:integer; newc:integer);
begin if not ofm_on then
  tfm[c+2]:=newc
else begin
  tfm[c+2]:=newc div 256;
  tfm[c+3]:=newc mod 256
  end
end;

function l_remainder(c:integer):integer;
begin if not ofm_on then
  l_remainder:=tfm[c+3]
else
  l_remainder:=256*tfm[c+6]+tfm[c+7];
end;

procedure set_l_remainder(c:integer; newc:char_type);
begin if not ofm_on then
  tfm[c+3]:=newc
else begin
  tfm[c+6]:=newc div 256;
  tfm[c+7]:=newc mod 256
  end
end;

@ One of the things we would like to do is take cognizance of fonts whose
character coding scheme is \.{TeX math symbols} or \.{TeX math extension};
we will set the |font_type| variable to one of the three choices
|vanilla|, |mathsy|, or |mathex|.

@d vanilla=0 {not a special scheme}
@d mathsy=1 {\.{TeX math symbols} scheme}
@d mathex=2 {\.{TeX math extension} scheme}

@<Glob...@>=
@!font_type:vanilla..mathex; {is this font special?}

@* Unpacking the VF file.
Once the \.{TFM} file has been brought into memory, \.{VFtoVP} completes
the input phase by reading the \.{VF} information into another array of bytes.
In this case we don't store all the data; we check the redundant bytes
for consistency with their \.{TFM} counterparts, and we partially decode
the packets.

@<Glob...@>=
@!vf:array[0..vf_size] of byte; {the \.{VF} input data goes here}
@!font_number:array[0..max_fonts] of integer; {local font numbers}
@!font_start,@!font_chars:array[0..max_fonts] of 0..vf_size; {font info}
@!font_ptr:0..max_fonts; {number of local fonts}
@!packet_start,@!packet_end:array[char_type] of 0..vf_size;
  {character packet boundaries}
@!packet_found:boolean; {at least one packet has appeared}
@!temp_byte:byte;@+@!reg_count:integer; {registers for simple calculations}
@!real_dsize:real; {the design size, converted to floating point}
@!pl:integer; {packet length}
@!vf_ptr:0..vf_size; {first unused location in |vf|}
@!vf_count:integer; {number of bytes read from |vf_file|}

@ Again we cautiously verify that we've been given decent data.

@d read_vf(#)==read(vf_file,#)
@d vf_abort(#)==begin
  print_ln(#);
  print_ln('Sorry, but I can''t go on; are you sure this is a OVF?');
  goto final_end;
  end

@<Read the whole \.{VF} file@>=
read_vf(temp_byte);
if temp_byte<>pre then vf_abort('The first byte isn''t `pre''!');
@.The first byte...@>
@<Read the preamble command@>;
@<Read and store the font definitions and character packets@>;
@<Read and verify the postamble@>

@ @d vf_store(#)==@t@>@;@/
  if vf_ptr+#>=vf_size then vf_abort('The file is bigger than I can handle!');
@.The file is bigger...@>
  for k:=vf_ptr to vf_ptr+#-1 do
    begin if eof(vf_file) then vf_abort('The file ended prematurely!');
@.The file ended prematurely@>
    read_vf(vf[k]);
    end;
  vf_count:=vf_count+#; vf_ptr:=vf_ptr+#

@<Read the preamble command@>=
if eof(vf_file) then vf_abort('The input file is only one byte long!');
@.The input...one byte long@>
read_vf(temp_byte);
if temp_byte<>id_byte then vf_abort('Wrong OVF version number in second byte!');
@.Wrong OVF version...@>
if eof(vf_file) then vf_abort('The input file is only two bytes long!');
read_vf(temp_byte); {read the length of introductory comment}
vf_count:=11; vf_ptr:=0; vf_store(temp_byte);
for k:=0 to vf_ptr-1 do print(xchr[vf[k]]);
print_ln(' '); reg_count:=0;
for k:=0 to 7 do
  begin if eof(vf_file) then vf_abort('The file ended prematurely!');
@.The file ended prematurely@>
  read_vf(temp_byte);
  if temp_byte=tfm[check_sum+k] then incr(reg_count);
  end;
real_dsize:=(((tfm[design_size]*256+tfm[design_size+1])*256+tfm[design_size+2])
 *256+tfm[design_size+3])/@'4000000;
if reg_count<>8 then
  begin print_ln('Check sum and/or design size mismatch.');
@.Check sum...mismatch@>
  print_ln('Data from OFM file will be assumed correct.');
  end

@ @<Read and store the font definitions and character packets@>=
for k:=0 to 65535 do packet_start[k]:=vf_size;
font_ptr:=0; packet_found:=false; font_start[0]:=vf_ptr;
repeat if eof(vf_file) then
  begin print_ln('File ended without a postamble!'); temp_byte:=post;
@.File ended without a postamble@>
  end
else begin read_vf(temp_byte); incr(vf_count);
  if temp_byte<>post then
    if temp_byte>long_char then @<Read and store a font definition@>
    else @<Read and store a character packet@>;
  end;
until temp_byte=post

@ @<Read and verify the postamble@>=
while (temp_byte=post)and not eof(vf_file) do
  begin read_vf(temp_byte); incr(vf_count);
  end;
if not eof(vf_file) then
  begin print_ln('There''s some extra junk at the end of the OVF file.');
@.There's some extra junk...@>
  print_ln('I''ll proceed as if it weren''t there.');
  end;
if vf_count mod 4 <> 0 then
  print_ln('VF data not a multiple of 4 bytes')
@.VF data not a multiple of 4 bytes@>

@ @<Read and store a font definition@>=
begin if packet_found or(temp_byte>=pre) then
  vf_abort('Illegal byte ',temp_byte:1,' at beginning of character packet!');
@.Illegal byte...@>
font_number[font_ptr]:=vf_read(temp_byte-fnt_def1+1);
if font_ptr=max_fonts then vf_abort('I can''t handle that many fonts!');
@.I can't handle that many fonts@>
vf_store(14); {|c[4]| |s[4]| |d[4]| |a[1]| |l[1]|}
if vf[vf_ptr-10]>0 then {|s| is negative or exceeds $2^{24}-1$}
  vf_abort('Mapped font size is too big!');
@.Mapped font size...big@>
a:=vf[vf_ptr-2]; l:=vf[vf_ptr-1]; vf_store(a+l); {|n[a+l]|}
@<Print the name of the local font@>;
@<Read the local font's \.{TFM} file and record the characters it contains@>;
incr(font_ptr); font_start[font_ptr]:=vf_ptr; 
end

@ The font area may need to be separated from the font name on some systems.
Here we simply reproduce the font area and font name (with no space
or punctuation between them).
@^system dependencies@>

@<Print the name...@>=
print('MAPFONT ',font_ptr:1,': ');
for k:=font_start[font_ptr]+14 to vf_ptr-1 do print(xchr[vf[k]]);
k:=font_start[font_ptr]+5;
print_ln(' at ',(((vf[k]*256+vf[k+1])*256+vf[k+2])/@'4000000)*real_dsize:2:2,
  'pt')

@ Now we must read in another \.{TFM} file. But this time we needn't be so
careful, because we merely want to discover which characters are present.
The next few sections of the program are copied pretty much verbatim from
\.{DVItype}, so that system-dependent modifications can be copied from existing
software.

It turns out to be convenient to read four bytes at a time, when we are
inputting from the local \.{TFM} files. The input goes into global variables
|b0|, |b1|, |b2|, and |b3|, with |b0| getting the first byte and |b3|
the fourth.

@<Glob...@>=
@!a:integer; {length of the area/directory spec}
@!l:integer; {length of the font name proper}
@!cur_name:packed array[1..name_length] of char; {external name,
  with no lower case letters}
@!b0,@!b1,@!b2,@!b3: byte; {four bytes input at once}
@!font_lh:integer; {header length of current local font}
@!font_bc,@!font_ec:integer; {character range of current local font}
@!font_ofm_level,@!font_extra_words:integer;
@!font_kprime,@!font_j:integer;

@ The |read_tfm_word| procedure sets |b0| through |b3| to the next
four bytes in the current \.{TFM} file.
@^system dependencies@>

@d read_tfm(#)==if eof(tfm_file) then #:=0@+else read(tfm_file,#)

@p procedure read_tfm_word;
begin read_tfm(b0); read_tfm(b1);
read_tfm(b2); read_tfm(b3);
end;

@ We use the |vf| array to store a list of all valid characters in the
local font, beginning at location |font_chars[f]|.

@<Read the local font's \.{TFM} file...@>=
font_chars[font_ptr]:=vf_ptr;
@<Move font name into the |cur_name| string@>;
reset(tfm_file,cur_name);
@^system dependencies@>
if eof(tfm_file) then
  print_ln('---not loaded, font metric file can''t be opened!')
@.font metric file can\'t be opened@>
else  begin font_bc:=0; font_ec:=65536; {will cause error if not modified soon}
  @<Read past the header@>;
  if font_bc<=font_ec then
    if font_ec>65535 then print_ln('---not loaded, bad font metric file!')
@.bad font metric file@>
    else @<Read |char_info| entries@>;
  if eof(tfm_file) then
    print_ln('---trouble is brewing, font metric file ended too soon!');
@.trouble is brewing...@>
  end;
incr(vf_ptr) {leave space for character search later}

@ @<Read past the header@>=
read_tfm_word;
if (b0*256+b1)<>0 then begin {TFM file}
  font_ofm_level:=-1;
  font_lh:=b2*256+b3;
  read_tfm_word; font_bc:=b0*256+b1; font_ec:=b2*256+b3;
  if font_ec<font_bc then font_bc:=font_ec+1;
  read_tfm_word;
  for k:=1 to 3+font_lh do begin
    read_tfm_word;
    if k=4 then @<Check the check sum@>;
    if k=5 then @<Check the design size@>;
    end;
  end
else begin
  font_ofm_level:=b2*256+b3;
  read_tfm_word; font_lh:=((b0*256+b1)*256+b2)*256+b3;
  read_tfm_word; font_bc:=((b0*256+b1)*256+b2)*256+b3;
  read_tfm_word; font_ec:=((b0*256+b1)*256+b2)*256+b3;
  if font_ec<font_bc then font_bc:=font_ec+1;
  read_tfm_word; 
  for k:=1 to 8 do begin
    read_tfm_word;
    end;
  if font_ofm_level=1 then begin
    read_tfm_word; read_tfm_word; read_tfm_word;
    font_extra_words:=(((b0*256+b1)*256+b2)*256+b3) div 2;
    for k:=1 to 5 do begin
      read_tfm_word;
      end;
    end;
  for k:=1 to lh do begin
    read_tfm_word;
    if k=1 then @<Check the check sum@>;
    if k=2 then @<Check the design size@>;
    end;
  end

@ @<Read |char_info| entries@>=
case font_ofm_level of
 -1: begin
    for k:=font_bc to font_ec do begin
      read_tfm_word;
      if b0>0 then begin {character |k| exists in the font}
        vf[vf_ptr]:=k; incr(vf_ptr);
        if vf_ptr=vf_size then vf_abort('I''m out of OVF memory!');
        end;
      end;
    end;
  0: begin
    for k:=font_bc to font_ec do
      begin read_tfm_word;
      if (b0*256+b1)>0 then {character |k| exists in the font}
        begin vf[vf_ptr]:=k; incr(vf_ptr);
        if vf_ptr=vf_size then vf_abort('I''m out of OVF memory!');
        end;
      read_tfm_word;
      end;
    end;
  1: begin
    k:=font_bc;
    while k<font_ec do begin
      read_tfm_word;
      if (b0*256+b1)>0 then begin {character |k| exists in the font}
        vf[vf_ptr]:=k; incr(vf_ptr);
        if vf_ptr=vf_size then vf_abort('I''m out of OVF memory!');
        end;
      read_tfm_word; read_tfm_word;
      font_kprime:=k+(b0*256+b1);
      for font_j:=k+1 to font_kprime do begin
        vf[vf_ptr]:=font_j; incr(vf_ptr);
        if vf_ptr=vf_size then vf_abort('I''m out of OVF memory!');
        end;
      k:=font_kprime;
      for font_j:=1 to font_extra_words do
        read_tfm_word;
      end
    end;
end;

@ @<Check the check sum@>=
if b0+b1+b2+b3>0 then
  if(b0<>vf[font_start[font_ptr]])or@|
   (b1<>vf[font_start[font_ptr]+1])or@|
   (b2<>vf[font_start[font_ptr]+2])or@|
   (b3<>vf[font_start[font_ptr]+3]) then begin
    print_ln('Check sum in OVF file being replaced by font metric check sum');
@.Check sum...replaced...@>
    vf[font_start[font_ptr]]:=b0;
    vf[font_start[font_ptr]+1]:=b1;
    vf[font_start[font_ptr]+2]:=b2;
    vf[font_start[font_ptr]+3]:=b3;
    end

@ @<Check the design size@>=
if(b0<>vf[font_start[font_ptr]+8])or@|
 (b1<>vf[font_start[font_ptr]+9])or@|
 (b2<>vf[font_start[font_ptr]+10])or@|
 (b3<>vf[font_start[font_ptr]+11]) then
  begin print_ln('Design size in OVF file being replaced by font metric design size');
@.Design size...replaced...@>
  vf[font_start[font_ptr]+8]:=b0;
  vf[font_start[font_ptr]+9]:=b1;
  vf[font_start[font_ptr]+10]:=b2;
  vf[font_start[font_ptr]+11]:=b3;
  end

@ If no font directory has been specified, \.{DVI}-reading software
is supposed to use the default font directory, which is a
system-dependent place where the standard fonts are kept.
The string variable |default_directory| contains the name of this area.
@^system dependencies@>

@d default_directory_name=='TeXfonts:' {change this to the correct name}
@d default_directory_name_length=9 {change this to the correct length}

@<Glob...@>=
@!default_directory:packed array[1..default_directory_name_length] of char;

@ @<Set init...@>=
default_directory:=default_directory_name;

@ The string |cur_name| is supposed to be set to the external name of the
\.{TFM} file for the current font. This usually means that we need to
prepend the name of the default directory, and
to append the suffix `\.{.TFM}'. Furthermore, we change lower case letters
to upper case, since |cur_name| is a \PASCAL\ string.
@^system dependencies@>

@<Move font name into the |cur_name| string@>=
for k:=1 to name_length do cur_name[k]:=' ';
if a=0 then begin
  for k:=1 to default_directory_name_length do
    cur_name[k]:=default_directory[k];
  r:=default_directory_name_length;
  end
else r:=0;
for k:=font_start[font_ptr]+14 to vf_ptr-1 do begin
  incr(r);
  if r+4>name_length then vf_abort('Font name too long for me!');
@.Font name too long for me@>
  if (vf[k]>="a")and(vf[k]<="z") then
      cur_name[r]:=xchr[vf[k]-@'40]
  else cur_name[r]:=xchr[vf[k]];
  end;
cur_name[r+1]:='.'; cur_name[r+2]:='T'; cur_name[r+3]:='F'; cur_name[r+4]:='M'


@ It's convenient to have a subroutine
that reads a |k|-byte number from |vf_file|.

@d get_vf(#)==if eof(vf_file) then #:=0 @+else read_vf(#)

@p function vf_read(@!k:integer):integer; {actually |1<=k<=4|}
var @!b:byte; {input byte}
@!a:integer; {accumulator}
begin vf_count:=vf_count+k; get_vf(b); a:=b;
if k=4 then if b>=128 then a:=a-256; {4-byte numbers are signed}
while k>1 do begin
  get_vf(b);
  a:=256*a+b; decr(k);
  end;
vf_read:=a;
end;

@ The \.{VF} format supports arbitrary 4-byte character codes,
but \.{VPL} format presently does not.  But \.{OVP} does.

@<Read and store a character packet@>=
begin if temp_byte=long_char then
  begin pl:=vf_read(4); c:=vf_read(4); reg_count:=vf_read(4);
    {|pl[4]| |cc[4]| |tfm[4]|}
  end
else begin pl:=temp_byte; c:=vf_read(1); reg_count:=vf_read(3);
    {|pl[1]| |cc[1]| |tfm[3]|}
  end;
if nonexistent(c) then vf_abort('Character ',c:1,' does not exist!');
@.Character c does not exist@>
if packet_start[c]<vf_size then
  print_ln('Discarding earlier packet for character ',c:1);
@.Discarding earlier packet...@>
if reg_count<>tfm_width(c) then
  print_ln('Incorrect OFM width for character ',c:1,' in OVF file');
@.Incorrect OFM width...@>
if pl<0 then vf_abort('Negative packet length!');
@.Negative packet length@>
packet_start[c]:=vf_ptr; vf_store(pl); packet_end[c]:=vf_ptr-1;
packet_found:=true;
end

@ The preceding code requires a simple subroutine that evaluates \.{TFM} data.

@p function tfm_width(@!c:integer):integer;
var @!a:integer; {accumulator}
@!k:index; {index into |tfm|}
begin k:=width(c); {we assume that character |c| exists}
a:=tfm[k];
if a>=128 then a:=a-256;
tfm_width:=((256*a+tfm[k+1])*256+tfm[k+2])*256+tfm[k+3];
end;

@* Basic output subroutines.
Let us now define some procedures that will reduce the rest of \.{VFtoVP}'s
work to a triviality.

First of all, it is convenient to have an abbreviation for output to the
\.{VPL} file:

@d out(#)==write(vpl_file,#)

@ In order to stick to standard \PASCAL, we use an |xchr| array to do
appropriate conversion of ASCII codes. Three other little strings are
used to produce |face| codes like \.{MIE}.

@<Glob...@>=
@!ASCII_04,@!ASCII_10,@!ASCII_14,HEX: packed array [1..32] of char;
  {strings for output in the user's external character set}
@!xchr:packed array [0..255] of char;
@!MBL_string,@!RI_string,@!RCE_string:packed array [1..3] of char;
  {handy string constants for |face| codes}

@ @<Set init...@>=
ASCII_04:=' !"#$%&''()*+,-./0123456789:;<=>?';@/
ASCII_10:='@@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_';@/
ASCII_14:='`abcdefghijklmnopqrstuvwxyz{|}~?';@/
HEX:='0123456789ABCDEF';@/
for k:=0 to 255 do xchr[k]:='?';
for k:=0 to @'37 do begin
  xchr[k+@'40]:=ASCII_04[k+1];
  xchr[k+@'100]:=ASCII_10[k+1];
  xchr[k+@'140]:=ASCII_14[k+1];
  end;
MBL_string:='MBL'; RI_string:='RI '; RCE_string:='RCE';

@ The array |dig| will hold a sequence of digits to be output.

@<Glob...@>=
@!dig:array[0..11] of integer;

@ Here, in fact, are two procedures that output
|dig[j-1]|$\,\ldots\,$|dig[0]|, given $j>0$.

@p procedure out_digs(j:integer); {outputs |j| digits}
begin repeat decr(j); out(HEX[1+dig[j]]);
  until j=0;
end;
@#
procedure print_digs(j:integer); {prints |j| digits}
begin repeat decr(j); print(HEX[1+dig[j]]);
  until j=0;
end;

@ The |print_number| procedure indicates how |print_digs| can be used.
This procedure can print in octal, decimal or hex notation.

@d print_hex(#)==print_number(#,16)
@d print_octal(#)==print_number(#,8)
@d print_decimal(#)==print_number(#,10)

@p procedure print_number(c:integer; form:integer); {prints value of |c|}
var j:0..32; {index into |dig|}
begin
j:=0;
if (c<0) then begin
  print_ln('Internal error: print_number (negative value)');
  c:=0;
  end;
if form=8 then
  print('''') {an apostrophe indicates the octal notation}
else if form=16 then
  print('"')  { a double apostrophe indicates the hexadecimal notation}
else if form<>10 then begin
  print_ln('Internal error: print_number (form)');
  form:=16;
  end;
while (c>0) or (j=0) do begin
  dig[j]:=c mod form; c:=c div form;
  j:=j+1;
  end;
print_digs(j);
end;

@ A \.{VPL} file has nested parentheses, and we want to format the output
so that its structure is clear. The |level| variable keeps track of the
depth of nesting.

@<Glob...@>=
@!level:0..5;

@ @<Set init...@>=
level:=0;

@ Three simple procedures suffice to produce the desired structure in the
output.

@p procedure out_ln; {finishes one line, indents the next}
var l:0..5;
begin write_ln(vpl_file);
for l:=1 to level do out('   ');
end;
@#
procedure left; {outputs a left parenthesis}
begin incr(level); out('(');
end;
@#
procedure right; {outputs a right parenthesis and finishes a line}
begin decr(level); out(')'); out_ln;
end;

@ The value associated with a property can be output in a variety of
ways. For example, we might want to output a {\mc BCPL} string that
begins in |tfm[k]|:

@p procedure out_BCPL(@!k:index); {outputs a string, preceded by a blank space}
var l:0..39; {the number of bytes remaining}
begin out(' '); l:=tfm[k];
while l>0 do begin
  incr(k); decr(l); out(xchr[tfm[k]]);
  end;
end;

@ The property value might also be a sequence of |l| bytes, beginning
in |tfm[k]|, that we would like to output in hex notation.
The following procedure assumes that |l<=4|, but larger values of |l|
could be handled easily by enlarging the |dig| array and increasing
the upper bounds on |b| and |j|.

@d out_octal_number(#)==out_number(#,8)
@d out_decimal_number(#)==out_number(#,10)
@d out_hex_number(#)==out_number(#,16)
@d out_dec(#)==out_decimal_number(#)
@d out_hex_char(#)==out_hex_number(#)

@p procedure out_number(c:integer; form:integer); {outputs value of |c|}
var j:0..32; {index into |dig|}
begin
j:=0;
if (c<0) then begin
  print_ln('Internal error: print_number (negative value)');
  c:=0;
  end;
if form=8 then
  out(' O ')
else if form=10 then
  out(' D ')
else if form=16 then
  out(' H ')
else begin
  print_ln('Internal error: print_number (form)');
  form:=16;
  out(' H ')
  end;
while (c>0) or (j=0) do begin
  dig[j]:=c mod form; c:=c div form;
  j:=j+1;
  end;
out_digs(j);
end;
@#
procedure out_hex(@!k,@!l:index);
   {outputs |l| bytes in hex}
var a:0..@"7FFFFFFF; {accumulator for bits not yet output}
@!b:0..32; {the number of significant bits in |a|}
@!j:0..11; {the number of digits of output}
begin
out(' H ');
a:=0; b:=0; j:=0;
while l>0 do @<Reduce \(1)|l| by one, preserving the invariants@>;
while (a>0)or(j=0) do begin
  dig[j]:=a mod 16; a:=a div 16; incr(j);
  end;
out_digs(j);
end;

@ @<Reduce \(1)|l|...@>=
begin decr(l);
if tfm[k+l]<>0 then begin
  while b>2 do begin
    dig[j]:=a mod 16; a:=a div 16; b:=b-4; incr(j);
    end;
  case b of
    0: a:=tfm[k+l];
    1:a:=a+2*tfm[k+l];
    2:a:=a+4*tfm[k+l];
    3:a:=a+8*tfm[k+l];
    end;
  end;
b:=b+8;
end

@ The property value may be a character, which is output in hex
unless it is a letter or a digit. This procedure is the only place
where a lowercase letter will be output to the \.{PL} file.
@^system dependencies@>

@p procedure out_char(@!c:integer); {outputs a character}
begin if font_type>vanilla then
  out_hex_char(c)
else if (c>="0")and(c<="9") then
  out(' C ',c-"0":1)
else if (c>="A")and(c<="Z") then
  out(' C ',ASCII_10[c-"A"+2])
else if (c>="a")and(c<="z") then
  out(' C ',ASCII_14[c-"a"+2])
else out_hex_char(c);
end;

@ The property value might be a ``face'' byte, which is output in the
curious code mentioned earlier, provided that it is less than 18.

@p procedure out_face(@!k:index); {outputs a |face|}
var s:0..1; {the slope}
@!b:0..8; {the weight and expansion}
begin if tfm[k]>=18 then out_hex(k,1)
else begin
  out(' F ');  {specify face-code format}
  s:=tfm[k] mod 2; b:=tfm[k] div 2;
  out(MBL_string[1+(b mod 3)]);
  out(RI_string[1+s]);
  out(RCE_string[1+(b div 3)]);
  end;
end;

@ And finally, the value might be a |fix_word|, which is output in
decimal notation with just enough decimal places for \.{VPtoVF}
to recover every bit of the given |fix_word|.

All of the numbers involved in the intermediate calculations of
this procedure will be nonnegative and less than $10\cdot2^{24}$.

@p procedure out_fix(@!k:index); {outputs a |fix_word|}
var a:0..@'7777; {accumulator for the integer part}
@!f:integer; {accumulator for the fraction part}
@!j:0..12; {index into |dig|}
@!delta:integer; {amount if allowable inaccuracy}
begin out(' R '); {specify real format}
a:=(tfm[k]*16)+(tfm[k+1] div 16);
f:=((tfm[k+1] mod 16)*@'400+tfm[k+2])*@'400+tfm[k+3];
if a>@'3777 then @<Reduce \(2)negative to positive@>;
@<Output the integer part, |a|, in decimal notation@>;
@<Output the fraction part, $|f|/2^{20}$, in decimal notation@>;
end;

@ The following code outputs at least one digit even if |a=0|.

@<Output the integer...@>=
begin j:=0;
repeat dig[j]:=a mod 10; a:=a div 10; incr(j);
until a=0;
out_digs(j);
end

@ And the following code outputs at least one digit to the right
of the decimal point.

@<Output the fraction...@>=
begin out('.'); f:=10*f+5; delta:=10;
repeat if delta>@'4000000 then f:=f+@'2000000-(delta div 2);
out(f div @'4000000:1); f:=10*(f mod @'4000000); delta:=delta*10;
until f<=delta;
end;

@ @<Reduce \(2)negative to positive@>=
begin out('-'); a:=@'10000-a;
if f>0 then begin
  f:=@'4000000-f; decr(a);
  end;
end

@* Outputting the TFM info.
\TeX\ checks the information of a \.{TFM} file for validity as the
file is being read in, so that no further checks will be needed when
typesetting is going on. And when it finds something wrong, it justs
calls the file ``bad,'' without identifying the nature of the problem,
since \.{TFM} files are supposed to be good almost all of the time.

Of course, a bad file shows up every now and again, and that's where
\.{VFtoVP} comes in. This program wants to catch at least as many errors as
\TeX\ does, and to give informative error messages besides.
All of the errors are corrected, so that the \.{VPL} output will
be correct (unless, of course, the \.{TFM} file was so loused up
that no attempt is being made to fathom it).

@ Just before each character is processed, its code is printed in hex
notation. Up to eight such codes appear on a line; so we have a variable
to keep track of how many are currently there. We also keep track of
whether or not any errors have had to be corrected.

@<Glob...@>=
@!chars_on_line:0..8; {the number of characters printed on the current line}
@!perfect:boolean; {was the file free of errors?}

@ @<Set init...@>=
chars_on_line:=0;@/
perfect:=true; {innocent until proved guilty}

@ Error messages are given with the help of the |bad| and |range_error|
and |bad_char| macros:

@d bad(#)==begin perfect:=false; if chars_on_line>0 then print_ln(' ');
  chars_on_line:=0; print_ln('Bad OFM file: ',#);
  end
@.Bad OFM file@>
@d range_error(#)==begin perfect:=false; print_ln(' ');
  print(#,' index for character ');
  print_hex(c); print_ln(' is too large;');
  print_ln('so I reset it to zero.');
  end
@d bad_char_tail(#)==print_hex(#); print_ln('.');
  end
@d bad_char(#)==begin perfect:=false; if chars_on_line>0 then print_ln(' ');
  chars_on_line:=0; print('Bad OFM file: ',#,' nonexistent character ');
  bad_char_tail
@d correct_bad_char_tail(#)==#(k,0)
  end
@d correct_bad_char_middle(#)==print_hex(#(k)); print_ln('.');
  correct_bad_char_tail
@d correct_bad_char(#)== begin perfect:=false;
  if chars_on_line>0 then print_ln(' ');
  chars_on_line:=0; print('Bad OFM file: ',#,' nonexistent character ');
  correct_bad_char_middle

@<Glob...@>=
@!i:integer; {an index to words of a subfile}
@!c:xchar_type; {a random character}
@!d:0..3; {byte number in a word}
@!k:index; {a random index}
@!r:0..65535; {a random two-byte value}
@!count:0..127; {for when we need to enumerate a small set}

@ There are a lot of simple things to do, and they have to be done one
at a time, so we might as well get down to business.  The first things
that \.{VFtoVP} will put into the \.{VPL} file appear in the header part.

@<Do the header@>=
begin
case ofm_level of
  0: begin out('(OFMLEVEL H 0)'); out_ln; end;
  1: begin out('(OFMLEVEL H 1)'); out_ln; end;
  end;
if ofm_on then begin
  left;
  if font_dir<=7 then out('FONTDIR')
  else out('NFONTDIR');
  case font_dir mod 8 of
    0: out(' TL');
    1: out(' LT');
    2: out(' TR');
    3: out(' LB');
    4: out(' BL');
    5: out(' RT');
    6: out(' BR');
    7: out(' RB');
    end;
  right
  end;
font_type:=vanilla;
if lh>=12 then begin
  @<Set the true |font_type|@>;
  if lh>=17 then begin
    @<Output the family name@>;
    if lh>=18 then @<Output the rest of the header@>;
    end;
  @<Output the character coding scheme@>;
  end;
@<Output the design size@>;
@<Output the check sum@>;
@<Output the |seven_bit_safe_flag|@>;
end

@ @<Output the check sum@>=
left; out('CHECKSUM'); out_hex(check_sum,4);
right

@ Incorrect design sizes are changed to 10 points.

@d bad_design(#)==begin bad('Design size ',#,'!');
@.Design size wrong@>
  print_ln('I''ve set it to 10 points.');
  out(' D 10');
  end

@ @<Output the design size@>=
left; out('DESIGNSIZE');
if tfm[design_size]>127 then bad_design('negative')
else if (tfm[design_size]=0)and(tfm[design_size+1]<16) then
  bad_design('too small')
else out_fix(design_size);
right;
out('(COMMENT DESIGNSIZE IS IN POINTS)'); out_ln;
out('(COMMENT OTHER SIZES ARE MULTIPLES OF DESIGNSIZE)'); out_ln
@.DESIGNSIZE IS IN POINTS@>

@ Since we have to check two different {\mc BCPL} strings for validity,
we might as well write a subroutine to make the check.

@p procedure check_BCPL(@!k,@!l:index); {checks a string of length |<l|}
var j:index; {runs through the string}
@!c:integer; {character being checked}
begin if tfm[k]>=l then begin
  bad('String is too long; I''ve shortened it drastically.');
@.String is too long...@>
  tfm[k]:=1;
  end;
for j:=k+1 to k+tfm[k] do begin
  c:=tfm[j];
  if (c="(")or(c=")") then
    begin bad('Parenthesis in string has been changed to slash.');
@.Parenthesis...changed to slash@>
    tfm[j]:="/";
    end
  else if (c<" ")or(c>"~") then begin
    bad('Nonstandard ASCII code has been blotted out.');
@.Nonstandard ASCII code...@>
    tfm[j]:="?";
    end
  else if (c>="a")and(c<="z") then tfm[j]:=c+"A"-"a"; {upper-casify letters}
  end;
end;

@ The |font_type| starts out |vanilla|; possibly we need to reset it.

@<Set the true |font_type|@>=
begin check_BCPL(scheme,40);
if (tfm[scheme]>=11)and@|(tfm[scheme+1]="T")and@|
  (tfm[scheme+2]="E")and@|(tfm[scheme+3]="X")and@|
  (tfm[scheme+4]=" ")and@|(tfm[scheme+5]="M")and@|
  (tfm[scheme+6]="A")and@|(tfm[scheme+7]="T")and@|
  (tfm[scheme+8]="H")and@|(tfm[scheme+9]=" ") then begin
  if (tfm[scheme+10]="S")and(tfm[scheme+11]="Y") then font_type:=mathsy
  else if (tfm[scheme+10]="E")and(tfm[scheme+11]="X") then font_type:=mathex;
  end;
end

@ @<Output the character coding scheme@>=
left; out('CODINGSCHEME');
out_BCPL(scheme);
right

@ @<Output the family name@>=
left; out('FAMILY');
check_BCPL(family,20);
out_BCPL(family);
right

@ @<Output the rest of the header@>=
begin left; out('FACE'); out_face(random_word+3); right;
for i:=18 to lh-1 do begin
  left; out('HEADER D ',i:1);
  out_hex(check_sum+4*i,@,4); right;
  end;
end

@ This program does not check to see if the |seven_bit_safe_flag| has the
correct setting, i.e., if it really reflects the seven-bit-safety of
the \.{TFM} file; the stated value is merely put into the \.{VPL} file.
The \.{VPtoVF} program will store a correct value and give a warning
message if a file falsely claims to be safe.

@<Output the |seven_bit_safe_flag|@>=
if (lh>17) and (tfm[random_word]>127) then begin
  left; out('SEVENBITSAFEFLAG FALSE'); right;
  end

@ The next thing to take care of is the list of parameters.

@<Do the parameters@>=
if np>0 then begin
  left; out('FONTDIMEN'); out_ln;
  for i:=1 to np do @<Check and output the $i$th parameter@>;
  right;
  end;
@<Check to see if |np| is complete for this font type@>;

@ @<Check to see if |np|...@>=
if (font_type=mathsy)and(np<>22) then
  print_ln('Unusual number of fontdimen parameters for a math symbols font (',
@.Unusual number of fontdimen...@>
    np:1,' not 22).')
else if (font_type=mathex)and(np<>13) then
  print_ln('Unusual number of fontdimen parameters for an extension font (',
    np:1,' not 13).')

@ All |fix_word| values except the design size and the first parameter
will be checked to make sure that they are less than 16.0 in magnitude,
using the |check_fix| macro:

@d check_fix_tail(#)==bad(#,' ',i:1,' is too big;');
  print_ln('I have set it to zero.');
  end
@d check_fix(#)==if (tfm[#]>0)and(tfm[#]<255) then
  begin tfm[#]:=0; tfm[(#)+1]:=0; tfm[(#)+2]:=0; tfm[(#)+3]:=0;
  check_fix_tail

@<Check and output the $i$th parameter@>=
begin left;
if i=1 then out('SLANT') {this parameter is not checked}
else  begin check_fix(param(i))('Parameter');@/
@.Parameter n is too big@>
  @<Output the name of parameter $i$@>;
  end;
out_fix(param(i)); right;
end

@ @<Output the name...@>=
if i<=7 then case i of
  2:out('SPACE');@+3:out('STRETCH');@+4:out('SHRINK');
  5:out('XHEIGHT');@+6:out('QUAD');@+7:out('EXTRASPACE')@+end
else if (i<=22)and(font_type=mathsy) then case i of
  8:out('NUM1');@+9:out('NUM2');@+10:out('NUM3');
  11:out('DENOM1');@+12:out('DENOM2');
  13:out('SUP1');@+14:out('SUP2');@+15:out('SUP3');
  16:out('SUB1');@+17:out('SUB2');
  18:out('SUPDROP');@+19:out('SUBDROP');
  20:out('DELIM1');@+21:out('DELIM2');
  22:out('AXISHEIGHT')@+end
else if (i<=13)and(font_type=mathex) then
  if i=8 then out('DEFAULTRULETHICKNESS')
  else out('BIGOPSPACING',i-8:1)
else out('PARAMETER D ',i:1)

@ @<Glob...@>=
@!start_counter,@!base_counter,@!number_entries:integer;
@!value:integer;

@ @<Do the ivalue parameters@>=
if nki>0 then begin
  start_counter:=ivalues_start*4;
  base_counter:=ivalues_base*4;
  for i:=0 to nki-1 do @<Check and output the $i$th ivalue table@>;
  end;

@ @<Check and output the $i$th ivalue table@>=
begin
left; out('FONTIVALUE'); out_hex_number(i); out_ln; 
number_entries:=256*tfm[start_counter+2]+tfm[start_counter+3];
for j:=0 to number_entries-1 do begin
  left; out('IVALUE'); out_hex_number(j); out_ln; 
  value:=256*tfm[base_counter+2]+tfm[base_counter+3];
  left; out('IVALUEVAL'); out_hex_number(value); right;
  right;
  base_counter:=base_counter+4;
  end;
right;
start_counter:=start_counter+4;;
end;

@ @<Do the fvalue parameters@>=
if nkf>0 then begin
  start_counter:=fvalues_start*4;
  base_counter:=fvalues_base*4;
  for i:=0 to nkf-1 do @<Check and output the $i$th fvalue table@>;
  end;

@ @<Check and output the $i$th fvalue table@>=
begin
left; out('FONTFVALUE'); out_hex_number(i); out_ln; 
number_entries:=256*tfm[start_counter+2]+tfm[start_counter+3];
for j:=0 to number_entries-1 do begin
  left; out('FVALUE'); out_hex_number(j); out_ln; 
  left; out('FVALUEVAL'); out_fix(base_counter); right;
  right;
  base_counter:=base_counter+4;
  end;
right;
start_counter:=start_counter+4;
end;

@ @<Do the mvalue parameters@>=
if nkm>0 then begin
  start_counter:=mvalues_start*4;
  base_counter:=mvalues_base*4;
  for i:=0 to nkm-1 do @<Check and output the $i$th mvalue table@>;
  end;

@ @<Check and output the $i$th mvalue table@>=
begin
left; out('FONTMVALUE'); out_hex_number(i); out_ln; 
number_entries:=256*tfm[start_counter+2]+tfm[start_counter+3];
for j:=0 to number_entries-1 do begin
  left; out('MVALUE'); out_hex_number(j); out_ln; 
  left; out('MVALUEVAL'); out_fix(base_counter); right;
  right;
  base_counter:=base_counter+4;
  end;
right;
start_counter:=start_counter+4;
end;

@ @<Do the rule parameters@>=
if nkr>0 then begin
  start_counter:=rules_start*4;
  base_counter:=rules_base*4;
  for i:=0 to nkr-1 do @<Check and output the $i$th rule table@>;
  end;

@ @<Check and output the $i$th rule table@>=
begin
left; out('FONTRULE'); out_hex_number(i); out_ln; 
number_entries:=256*tfm[start_counter+2]+tfm[start_counter+3];
for j:=0 to number_entries-1 do begin
  left; out('RULE'); out_hex_number(j); out_ln; 
  left; out('RULEWD'); out_fix(base_counter); right;
  left; out('RULEHT'); out_fix(base_counter+4); right;
  left; out('RULEDP'); out_fix(base_counter+8); right;
  right;
  base_counter:=base_counter+12;
  end;
right;
start_counter:=start_counter+4;
end;

@ @<Do the glue parameters@>=
if nkg>0 then begin
  start_counter:=glues_start*4;
  base_counter:=glues_base*4;
  for i:=0 to nkg-1 do @<Check and output the $i$th glue table@>;
  end;

@ @<Glob...@>=
@!glue_subtype,@!glue_argument_kind,@!glue_stretch_order,
@!glue_shrink_order,@!glue_argument:integer;

@ @<Check and output the $i$th glue table@>=
begin
left; out('FONTGLUE'); out_hex_number(i); out_ln; 
number_entries:=256*tfm[start_counter+2]+tfm[start_counter+3];
for j:=0 to number_entries-1 do begin
  left; out('GLUE'); out_hex_number(j); out_ln; 
  glue_subtype:=tfm[base_counter] div 16;
  glue_argument_kind:=tfm[base_counter] mod 16;
  glue_stretch_order:=tfm[base_counter+1] div 16;
  glue_shrink_order:=tfm[base_counter+1] mod 16;
  glue_argument:=tfm[base_counter+2]*256+tfm[base_counter+3];
  left;
  out('GLUETYPE'); 
  case glue_subtype of
    0: out(' H 0');
    1: out(' H 1');
    2: out(' H 2');
    3: out(' H 3');
    end;
  right;
  case glue_argument_kind of
    1: begin
      left; out('GLUERULE'); out_hex_number(glue_argument); right;
      end; 
    2: begin
      left; out('GLUECHAR'); out_hex_number(glue_argument); right;
      end; 
    end;
  left;
  out('GLUESTRETCHORDER'); 
  case glue_stretch_order of
    0: out(' H 0');
    1: out(' H 1');
    2: out(' H 2');
    3: out(' H 3');
    4: out(' H 4');
    end;
  right;
  left;
  out('GLUESHRINKORDER'); 
  case glue_shrink_order of
    0: out(' H 0');
    1: out(' H 1');
    2: out(' H 2');
    3: out(' H 3');
    4: out(' H 4');
    end;
  right;
  left; out('GLUEWD'); out_fix(base_counter+4); right;
  left; out('GLUESTRETCH'); out_fix(base_counter+8); right;
  left; out('GLUESHRINK'); out_fix(base_counter+12); right;
  right;
  base_counter:=base_counter+16;
  end;
right;
start_counter:=start_counter+4;
end;

@ @<Do the penalty parameters@>=
if nkp>0 then begin
  start_counter:=penalties_start*4;
  base_counter:=penalties_base*4;
  for i:=0 to nkp-1 do @<Check and output the $i$th penalty table@>;
  end;
 
@ @<Check and output the $i$th penalty table@>=
begin 
left; out('FONTPENALTY'); out_hex_number(i); out_ln; 
number_entries:=256*tfm[start_counter+2]+tfm[start_counter+3]; 
for j:=0 to number_entries-1 do begin 
  left; out('PENALTY'); out_hex_number(j); out_ln;
  value:=256*tfm[base_counter+2]+tfm[base_counter+3]; 
  left; out('PENALTYVAL'); out_hex_number(value); right; 
  right; 
  base_counter:=base_counter+4; 
  end; 
right;
start_counter:=start_counter+4; 
end;

@ We need to check the range of all the remaining |fix_word| values,
and to make sure that |width[0]=0|, etc.

@d nonzero_fix(#)==(tfm[#]>0)or(tfm[#+1]>0)or(tfm[#+2]>0)or(tfm[#+3]>0)

@<Check the |fix_word| entries@>=
if nonzero_fix(4*width_base) then bad('width[0] should be zero.');
@.should be zero@>
if nonzero_fix(4*height_base) then bad('height[0] should be zero.');
if nonzero_fix(4*depth_base) then bad('depth[0] should be zero.');
if nonzero_fix(4*italic_base) then bad('italic[0] should be zero.');
for i:=0 to nw-1 do check_fix(4*(width_base+i))('Width');
@.Width n is too big@>
for i:=0 to nh-1 do check_fix(4*(height_base+i))('Height');
@.Height n is too big@>
for i:=0 to nd-1 do check_fix(4*(depth_base+i))('Depth');
@.Depth n is too big@>
for i:=0 to ni-1 do check_fix(4*(italic_base+i))('Italic correction');
@.Italic correction n is too big@>
if nk>0 then for i:=0 to nk-1 do check_fix(kern(i))('Kern');
@.Kern n is too big@>

@ The ligature/kerning program comes next. Before we can put it out in
\.{PL} format, we need to make a table of ``labels'' that will be inserted
into the program. For each character |c| whose |tag| is |lig_tag| and
whose starting address is |r|, we will store the pair |(c,r)| in the
|label_table| array. If there's a boundary-char program starting at~|r|,
we also store the pair |(256,r)|.
This array is sorted by its second components, using the
simple method of straight insertion.

@<Glob...@>=
@!label_table:array[xxxchar_type] of record
@!cc:xchar_type;@!rr:0..lig_size;ischar:boolean;end;
@!label_ptr:xxchar_type; {the largest entry in |label_table|}
@!sort_ptr:xxchar_type; {index into |label_table|}
@!boundary_char:xchar_type; {boundary character, or |xmax_char| if none}
@!bchar_label:0..xmax_label; {beginning of boundary character program}

@ @<Set init...@>=
boundary_char:=xmax_char; bchar_label:=xmax_label;@/
label_ptr:=0; label_table[0].rr:=0; {a sentinel appears at the bottom}

@ We'll also identify and remove inaccessible program steps, using the
|activity| array.

@d unreachable=0 {a program step not known to be reachable}
@d pass_through=1 {a program step passed through on initialization}
@d accessible=2 {a program step that can be relevant}

@<Glob...@>=
@!activity:array[0..lig_size] of unreachable..accessible;
@!ai,@!acti:0..lig_size; {indices into |activity|}

@ @<Do the ligatures and kerns@>=
if nl>0 then begin
  for ai:=0 to (nl-1) do activity[ai]:=unreachable;
  @<Check for a boundary char@>;
  end;
@<Build the label table@>;
if nl>0 then begin
  left; out('LIGTABLE'); out_ln;@/
  @<Compute the |activity| array@>;
  @<Output and correct the ligature/kern program@>;
  right;
  @<Check for ligature cycles@>;
  end

@ We build the label table even when |nl=0|, because this catches errors
that would not otherwise be detected.

@<Build...@>=
for c:=bc to ec do
if (tag(c)=lig_tag) or (ctag(c)) then begin
  r:=rremainder(c);
  if (l_skip_byte(lig_step(r)) div 256)=0 then begin
    if r<nl then begin
      if l_skip_byte(lig_step(r))>stop_flag then begin
        r:=256*l_op_byte(lig_step(r))+l_remainder(lig_step(r));
        if r<nl then if activity[rremainder(c)]=unreachable then
          activity[rremainder(c)]:=pass_through;
        end;
      end;
    end;
  if r>=nl then begin
    perfect:=false; print_ln(' ');
    print('Ligature/kern starting index for character '); print_hex(c);
    print_ln(' is too large;'); print_ln('so I removed it.'); set_no_tag(c);
    set_no_ctag(c);
@.Ligature/kern starting index...@>
    end
  else @<Insert |(c,r)| into |label_table|@>;
  end;
label_table[label_ptr+1].rr:=lig_size; {put ``infinite'' sentinel at the end}

@ @<Insert |(c,r)|...@>=
begin sort_ptr:=label_ptr; {there's a hole at position |sort_ptr+1|}
while label_table[sort_ptr].rr>r do begin
  label_table[sort_ptr+1]:=label_table[sort_ptr];
  decr(sort_ptr); {move the hole}
  end;
label_table[sort_ptr+1].ischar:=not ctag(c);
if ctag(c) then
  label_table[sort_ptr+1].cc:=char_param(c,0)
else
  label_table[sort_ptr+1].cc:=c;
label_table[sort_ptr+1].rr:=r; {fill the hole}
incr(label_ptr); activity[r]:=accessible;
end

@ @<Check for a bound...@>=
if l_skip_byte(lig_step(0))=255 then begin
  left; out('BOUNDARYCHAR');
  boundary_char:=l_next_char(lig_step(0)); out_char(boundary_char); right;
  activity[0]:=pass_through;
  end;
if l_skip_byte(lig_step(nl-1))=255 then begin
  r:=256*l_op_byte(lig_step(nl-1))+l_remainder(lig_step(nl-1));
  if r>=nl then begin
    perfect:=false; print_ln(' ');
    print('Ligature/kern starting index for boundarychar is too large;');
    print_ln('so I removed it.');
@.Ligature/kern starting index...@>
    end
  else begin
    label_ptr:=1; label_table[1].cc:=xmax_char;
    label_table[1].rr:=r;
    bchar_label:=r; activity[r]:=accessible;
    end;
  activity[nl-1]:=pass_through;
  end

@ @<Compute the |activity| array@>=
for ai:=0 to (nl-1) do
if (l_skip_byte(lig_step(ai)) div 256)=1 then
  activity[ai]:=accessible
else if activity[ai]=accessible then begin
  r:=l_skip_byte(lig_step(ai));
  if r<stop_flag then begin
    r:=r+ai+1;
    if r>=nl then begin
      bad('Ligature/kern step ',ai:1,' skips too far;');
@.Lig...skips too far@>
      print_ln('I made it stop.'); set_l_skip_byte(lig_step(ai),stop_flag);
      end
    else activity[r]:=accessible;
    end;
  end

@ We ignore |pass_through| items, which don't need to be mentioned in
the \.{PL} file.

@<Output and correct the ligature...@>=
sort_ptr:=1; {point to the next label that will be needed}
for acti:=0 to nl-1 do if activity[acti]<>pass_through then begin
  i:=acti; @<Take care of commenting out unreachable steps@>;
  @<Output any labels for step $i$@>;
  @<Output step $i$ of the ligature/kern program@>;
  end;
if level=2 then right {the final step was unreachable}

@ @<Globals...@>=
@!output_clabels:array[0..256] of boolean;
@!clabel_runner:integer;
@!cprime:integer;

@ @<Set init...@>=
for clabel_runner:=0 to 256 do
  output_clabels[clabel_runner]:=false;

@ @<Output any labels...@>=
while i=label_table[sort_ptr].rr do begin
  if not label_table[sort_ptr].ischar then begin
    if not output_clabels[label_table[sort_ptr].cc] then begin
      output_clabels[label_table[sort_ptr].cc]:=true;
      left;
      out('CLABEL');
      out_char(label_table[sort_ptr].cc);
      right;
      end
    end
  else begin
    left;
    out('LABEL');
    if label_table[sort_ptr].cc=xmax_char then out(' BOUNDARYCHAR')
    else out_char(label_table[sort_ptr].cc);
    right;
    end;
  incr(sort_ptr);
  end

@ @<Take care of commenting out...@>=
if activity[i]=unreachable then begin
  if level=1 then begin
    left; out('COMMENT THIS PART OF THE PROGRAM IS NEVER USED!'); out_ln;
    end
  end
else if level=2 then right

@ @<Output step $i$...@>=
begin k:=lig_step(i);
if (l_skip_byte(k) div 256)=1 then begin
  case l_op_byte(k) of
    17: begin
      left; out('CPEN');
      out_hex_number(l_next_char(k));
      out_hex_number(l_remainder(k));
      right;
      end;
    18: begin
      left; out('CGLUE');
      out_hex_number(l_next_char(k));
      out_hex_number(l_remainder(k));
      right;
      end;
    19: begin
      left; out('CPENGLUE');
      out_hex_number(l_next_char(k));
      out_hex_number(l_remainder(k) div 256);
      out_hex_number(l_remainder(k) mod 256);
      right;
      end;
    20: begin
      left; out('CKRN');
      out_hex_number(l_next_char(k));
      r:=l_remainder(k);
      if r>=nk then begin
        bad('Kern index too large.');
@.Kern index too large@>
        out(' R 0.0');
        end
      else out_fix(kern(r));
      right;
      end;
    end;
  end
else if l_skip_byte(k)>stop_flag then begin
  if (256*l_op_byte(k)+l_remainder(k))>=nl then
    bad('Ligature unconditional stop command address is too big.');
@.Ligature unconditional stop...@>
  end
else if l_op_byte(k)>=kern_flag then @<Output a kern step@>
else @<Output a ligature step@>;
if (l_skip_byte(k) mod 256)>0 then
  if level=1 then @<Output either \.{SKIP} or \.{STOP}@>;
end

@ The \.{SKIP} command is a bit tricky, because we will be omitting all
inaccessible commands.

@<Output either...@>=
begin if (l_skip_byte(k) mod 256)>=stop_flag then out('(STOP)')
else begin
  count:=0;
  for ai:=(i+1) to (i+(l_skip_byte(k) mod 256)) do
    if activity[ai]=accessible then incr(count);
  out('(SKIP D ',count:1,')'); {possibly $count=0$, so who cares}
  end;
out_ln;
end

@ @<Output a kern step@>=
begin if nonexistent(l_next_char(k)) then
         if l_next_char(k)<>boundary_char then
  correct_bad_char('Kern step for')(l_next_char)(set_l_next_char);
@.Kern step for nonexistent...@>
left; out('KRN'); out_char(l_next_char(k));
r:=256*(l_op_byte(k)-kern_flag)+l_remainder(k);
if r>=nk then begin
  bad('Kern index too large.');
@.Kern index too large@>
  out(' R 0.0');
  end
else out_fix(kern(r));
right;
end

@ @<Output a ligature step@>=
begin if nonexistent(l_next_char(k)) then
         if l_next_char(k)<>boundary_char then
  correct_bad_char('Ligature step for')(l_next_char)(set_l_next_char);
@.Ligature step for nonexistent...@>
if nonexistent(l_remainder(k)) then
correct_bad_char('Ligature step produces the')(l_remainder)(set_l_remainder);
@.Ligature step produces...@>
left; r:=l_op_byte(k);
if (r=4)or((r>7)and(r<>11)) then begin
  print_ln('Ligature step with nonstandard code changed to LIG');
  r:=0; set_l_op_byte(k,0);
  end;
if r mod 4>1 then out('/');
out('LIG');
if odd(r) then out('/');
while r>3 do begin
  out('>'); r:=r-4;
  end;
out_char(l_next_char(k)); out_char(l_remainder(k)); right;
end

@ The last thing on \.{VFtoVP}'s agenda is to go through the
list of |char_info| and spew out the information about each individual
character.

@<Do the characters@>=
sort_ptr:=0; {this will suppress `\.{STOP}' lines in ligature comments}
c:=bc;
while (c<=ec) do begin
  if width_index(c)>0 then begin
    if chars_on_line=8 then begin
      print_ln(' '); chars_on_line:=1;
      end
    else begin
      if chars_on_line>0 then print(' ');
      incr(chars_on_line);
      end;
    for cprime:=c to (c+no_repeats(c)) do begin
      print_hex(cprime); {progress report}
      left; out('CHARACTER'); out_char(cprime); out_ln;
      @<Output the character's width@>;
      if height_index(c)>0 then @<Output the character's height@>;
      if depth_index(c)>0 then @<Output the character's depth@>;
      if italic_index(c)>0 then @<Output the italic correction@>;
      case tag(c) of
        no_tag: do_nothing;
        lig_tag: @<Output the applicable part of the ligature/kern
                   program as a comment@>;
        list_tag: @<Output the character link unless there is a problem@>;
        ext_tag: @<Output an extensible character recipe@>;
        end; {there are no other cases}
      for i:=0 to npc-1 do begin
        if char_param(c,i)<>0 then begin
          left;
          if i<nki then begin
            out('CHARIVALUE'); out_hex_number(i);
            end
          else if i<(nki+nkf) then begin
            out('CHARFVALUE'); out_hex_number(i-nki);
            end
          else if i<(nki+nkf+nkr) then begin
            out('CHARRULE'); out_hex_number(i-nki-nkf);
            end
          else if i<(nki+nkf+nkr+nkg) then begin
            out('CHARGLUE'); out_hex_number(i-nki-nkf-nkr);
            end
          else if i<(nki+nkf+nkr+nkg+nkp) then begin
            out('CHARPENALTY'); out_hex_number(i-nki-nkf-nkr-nkg);
            end;
          out_hex_number(char_param(c,i));
          right;
          end;
        end;
      if not do_map(cprime) then goto final_end;
      right;
      end;
    end;
  c:=c+1+no_repeats(c);
  end

@ @<Output the character's width@>=
if width_index(c)>=nw then range_error('Width')
@.Width index for char...@>
else begin left; out('CHARWD'); out_fix(width(c)); right;
  end

@ @<Output the character's height@>=
if height_index(c)>=nh then range_error('Height')
@.Height index for char...@>
else  begin left; out('CHARHT'); out_fix(height(c)); right;
  end

@ @<Output the character's depth@>=
if depth_index(c)>=nd then range_error('Depth')
@.Depth index for char@>
else  begin left; out('CHARDP'); out_fix(depth(c)); right;
  end

@ @<Output the italic correction@>=
if italic_index(c)>=ni then range_error('Italic correction')
@.Italic correction index for char...@>
else  begin left; out('CHARIC'); out_fix(italic(c)); right;
  end

@ @<Output the applicable part of the ligature...@>=
begin left; out('COMMENT'); out_ln;@/
i:=rremainder(c); r:=lig_step(i);
if (l_skip_byte(r) mod 256)>stop_flag
then i:=256*l_op_byte(r)+l_remainder(r);
repeat @<Output step...@>;
if (l_skip_byte(k) mod 256)>=stop_flag then i:=nl
else i:=i+1+(l_skip_byte(k) mod 256);
until i>=nl;
right;
end

@ We want to make sure that there is no cycle of characters linked together
by |list_tag| entries, since such a cycle would get \TeX\ into an endless
loop. If such a cycle exists, the routine here detects it when processing
the largest character code in the cycle.

@<Output the character link unless there is a problem@>=
begin r:=rremainder(c);
if nonexistent(r) then begin
  bad_char('Character list link to')(r); set_no_tag(c);
@.Character list link...@>
  end
else begin
  while (r<c)and(tag(r)=list_tag) do r:=rremainder(r);
  if r=c then begin
    bad('Cycle in a character list!');
@.Cycle in a character list@>
    print('Character '); print_hex(c);
    print_ln(' now ends the list.');
    set_no_tag(c);
    end
  else begin
    left; out('NEXTLARGER'); out_char(rremainder(c));
    right;
    end;
  end;
end

@ @<Output an extensible character recipe@>=
if rremainder(c)>=ne then begin
  range_error('Extensible'); set_no_tag(c);
@.Extensible index for char@>
  end
else begin
  left; out('VARCHAR'); out_ln;
  @<Output the extensible pieces that exist@>;
  right;
  end

@ @<Glob...@>=
@!exten_char:integer;

@ @<Output the extensible pieces that...@>=
for d:=0 to 3 do begin
  if not ofm_on then begin
    k:=exten(c)+d;
    exten_char:=tfm[k];
    end
  else begin
    k:=exten(c)+2*d;
    exten_char:=256*tfm[k]+tfm[k+1];
    end;
  if (d=3)or(exten_char>0) then begin
    left;
    case d of
      0:out('TOP');@+1:out('MID');@+2:out('BOT');@+3:out('REP')@+end;
      if nonexistent(exten_char) then out_char(c)
      else out_char(exten_char);
      right;
    end
  end

@ Some of the extensible recipes may not actually be used, but \TeX\ will
complain about them anyway if they refer to nonexistent characters.
Therefore \.{VFtoVP} must check them too.

@<Check the extensible recipes@>=
if ne>0 then
  for c:=0 to ne-1 do
    for d:=0 to 3 do begin
      if not ofm_on then begin
        k:=4*(exten_base+c)+d;
        exten_char:=tfm[k];
        end
      else begin
        k:=4*(exten_base+c)+2*d;
        exten_char:=256*tfm[k]+tfm[k+1];
        end;
      if (exten_char>0)or(d=3) then begin
        if nonexistent(exten_char) then begin
          bad_char('Extensible recipe involves the')(exten_char);
@.Extensible recipe involves...@>
          if d<3 then begin
            if not ofm_on then begin
              tfm[k]:=0;
              end
            else begin
              tfm[k]:=0;
              tfm[k+1]:=0;
              end;
            end;
          end;
        end;
      end

@* Checking for ligature loops.
We have programmed almost everything but the most interesting calculation of
all, which has been saved for last as a special treat. \TeX's extended
ligature mechanism allows unwary users to specify sequences of ligature
replacements that never terminate. For example, the pair of commands
$$\.{(/LIG $x$ $y$) (/LIG $y$ $x$)}$$
alternately replaces character $x$ by character $y$ and vice versa. A similar
loop occurs if \.{(LIG/ $z$ $y$)} occurs in the program for $x$ and
 \.{(LIG/ $z$ $x$)} occurs in the program for $y$.

More complicated loops are also possible. For example, suppose the ligature
programs for $x$ and $y$ are
$$\vcenter{\halign{#\hfil\cr
\.{(LABEL $x$)(/LIG/ $z$ $w$)(/LIG/> $w$ $y$)} \dots,\cr
\.{(LABEL $y$)(LIG $w$ $x$)} \dots;\cr}}$$
then the adjacent characters $xz$ change to $xwz$, $xywz$, $xxz$, $xxwz$,
\dots, ad infinitum.

@ To detect such loops, \.{TFtoPL} attempts to evaluate the function
$f(x,y)$ for all character pairs $x$ and~$y$, where $f$ is defined as
follows: If the current character is $x$ and the next character is
$y$, we say the ``cursor'' is between $x$ and $y$; when the cursor
first moves past $y$, the character immediately to its left is
$f(x,y)$. This function is defined if and only if no infinite loop is
generated when the cursor is between $x$ and~$y$.

The function $f(x,y)$ can be defined recursively. It turns out that all pairs
$(x,y)$ belong to one of five classes. The simplest class has $f(x,y)=y$;
this happens if there's no ligature between $x$ and $y$, or in the cases
\.{LIG/>} and \.{/LIG/>>}. Another simple class arises when there's a
\.{LIG} or \.{/LIG>} between $x$ and~$y$, generating the character~$z$;
then $f(x,y)=z$. Otherwise we always have $f(x,y)$ equal to
either $f(x,z)$ or $f(z,y)$ or $f(f(x,z),y)$, where $z$ is the inserted
ligature character.

The first two of these classes can be merged; we can also consider
$(x,y)$ to belong to the simple class when $f(x,y)$ has been evaluated.
For technical reasons we allow $x$ to be 256 (for the boundary character
at the left) or 257 (in cases when an error has been detected).

For each pair $(x,y)$ having a ligature program step, we store
$(x,y)$ in a hash table from which the values $z$ and $class$ can be read.

@d simple=0 {$f(x,y)=z$}
@d left_z=1 {$f(x,y)=f(z,y)$}
@d right_z=2 {$f(x,y)=f(x,z)$}
@d both_z=3 {$f(x,y)=f(f(x,z),y)$}
@d pending=4 {$f(x,y)$ is being evaluated}

@<Glob...@>=
@!hash:array[0..hash_size] of integer;
@!class:array[0..hash_size] of simple..pending;
@!lig_z:array[0..hash_size] of xxchar_type;
@!hash_ptr:0..hash_size; {the number of nonzero entries in |hash|}
@!hash_list:array[0..hash_size] of 0..hash_size;
  {list of those nonzero entries}
@!h,@!hh:0..hash_size; {indices into the hash table}
@!x_lig_cycle,@!y_lig_cycle:xchar_type; {problematic ligature pair}

@ @<Check for ligature cycles@>=
hash_ptr:=0; y_lig_cycle:=xmax_char;
for hh:=0 to hash_size do hash[hh]:=0; {clear the hash table}
for c:=bc to ec do if tag(c)=lig_tag then begin
  i:=rremainder(c);
  if (l_skip_byte(lig_step(i)) mod 256)>stop_flag then
    i:=256*l_op_byte(lig_step(i))+l_remainder(lig_step(i));
  @<Enter data for character $c$ starting at location |i| in the hash table@>;
  end;
if bchar_label<nl then begin
  c:=xmax_char; i:=bchar_label;
  @<Enter data for character $c$ starting at location |i| in the hash table@>;
  end;
if hash_ptr=hash_size then begin
  print_ln('Sorry, I haven''t room for so many ligature/kern pairs!');
@.Sorry, I haven't room...@>
  goto final_end;
  end;
for hh:=1 to hash_ptr do begin
  r:=hash_list[hh];
  if class[r]>simple then {make sure $f$ is defined}
     r:=f(r,(hash[r]-1)div xmax_char,(hash[r]-1)mod xmax_char);
  end;
if y_lig_cycle<xmax_char then begin
  print('Infinite ligature loop starting with ');
@.Infinite ligature loop...@>
  if x_lig_cycle=xmax_char
  then print('boundary')@+else print_hex(x_lig_cycle);
  print(' and '); print_hex(y_lig_cycle); print_ln('!');
  out('(INFINITE LIGATURE LOOP MUST BE BROKEN!)'); goto final_end;
  end

@ @<Enter data for character $c$...@>=
repeat hash_input; k:=l_skip_byte(lig_step(i));
if k>=stop_flag then i:=nl
else i:=i+1+k;
until i>=nl

@ We use an ``ordered hash table'' with linear probing, because such a table
is efficient when the lookup of a random key tends to be unsuccessful.

@p procedure hash_input; {enter data for character |c| and command |i|}
label 30; {go here for a quick exit}
var @!cc:simple..both_z; {class of data being entered}
@!zz:char_type; {function value or ligature character being entered}
@!y:char_type; {the character after the cursor}
@!key:integer; {value to be stored in |hash|}
@!t:integer; {temporary register for swapping}
begin if hash_ptr=hash_size then goto 30;
@<Compute the command parameters |y|, |cc|, and |zz|@>;
key:=xmax_char*c+y+1; h:=(hash_mult*(key mod hash_size)) mod hash_size;
while hash[h]>0 do begin
  if hash[h]<=key then begin
    if hash[h]=key then goto 30; {unused ligature command}
    t:=hash[h]; hash[h]:=key; key:=t; {do ordered-hash-table insertion}
    t:=class[h]; class[h]:=cc; cc:=t; {namely, do a swap}
    t:=lig_z[h]; lig_z[h]:=zz; zz:=t;
    end;
  if h>0 then decr(h)@+else h:=hash_size;
  end;
hash[h]:=key; class[h]:=cc; lig_z[h]:=zz;
incr(hash_ptr); hash_list[hash_ptr]:=h;
30:end;

@ We must store kern commands as well as ligature commands, because
the former might make the latter inapplicable.

@<Compute the command param...@>=
k:=lig_step(i); y:=l_next_char(k); t:=l_op_byte(k);
cc:=simple; zz:=l_remainder(k);
if t>=kern_flag then zz:=y
else begin case t of
  0,6:do_nothing; {\.{LIG},\.{/LIG>}}
  5,11:zz:=y; {\.{LIG/>}, \.{/LIG/>>}}
  1,7:cc:=left_z; {\.{LIG/}, \.{/LIG/>}}
  2:cc:=right_z; {\.{/LIG}}
  3:cc:=both_z; {\.{/LIG/}}
  end; {there are no other cases}
  end

@ Evaluation of $f(x,y)$ is handled by two mutually recursive procedures.
Kind of a neat algorithm, generalizing a depth-first search.

@p function f(@!h,@!x,@!y:index):index; forward;@t\2@>
  {compute $f$ for arguments known to be in |hash[h]|}
function eval(@!x,@!y:index):index; {compute $f(x,y)$ with hashtable lookup}
var @!key:integer; {value sought in hash table}
begin key:=xmax_char*x+y+1; h:=(hash_mult*key) mod hash_size;
while hash[h]>key do
  if h>0 then decr(h)@+else h:=hash_size;
if hash[h]<key then eval:=y {not in ordered hash table}
else eval:=f(h,x,y);
end;

@ Pascal's beastly convention for |forward| declarations prevents us from
saying |function f(h,x,y:index):index| here.

@p function f;
begin case class[h] of
simple: do_nothing;
left_z: begin class[h]:=pending; lig_z[h]:=eval(lig_z[h],y); class[h]:=simple;
  end;
right_z: begin class[h]:=pending; lig_z[h]:=eval(x,lig_z[h]); class[h]:=simple;
  end;
both_z: begin class[h]:=pending; lig_z[h]:=eval(eval(x,lig_z[h]),y);
  class[h]:=simple;
  end;
pending: begin x_lig_cycle:=x; y_lig_cycle:=y;
  lig_z[h]:=xxmax_char; class[h]:=simple;
  end; {the value |xxmax_char| will break all cycles, 
        since it's not in |hash|}
end; {there are no other cases}
f:=lig_z[h];
end;

@* Outputting the VF info.
The routines we've used for output from the |tfm| array have counterparts
for output from |vf|. One difference is that the string outputs from |vf|
need to be checked for balanced parentheses. The |string_balance| routine
tests the string of length~|l| that starts at location~|k|.

@p function string_balance(@!k,@!l:integer):boolean;
label not_found,exit;
var @!j,@!bal:integer;
begin if l>0 then if vf[k]=" " then goto not_found;
  {a leading blank is considered unbalanced}
bal:=0;
for j:=k to k+l-1 do begin
  if (vf[j]<" ")or(vf[j]>=127) then goto not_found;
  if vf[j]="(" then incr(bal)
  else if vf[j]=")" then
    if bal=0 then goto not_found else decr(bal);
  end;
if bal>0 then goto not_found;
string_balance:=true; return;
not_found:string_balance:=false;
exit:end;

@ @d bad_vf(#)==begin perfect:=false; if chars_on_line>0 then print_ln(' ');
  chars_on_line:=0; print_ln('Bad OVF file: ',#);
  end
@.Bad OVF file@>

@<Do the virtual font title@>=
if string_balance(0,font_start[0]) then begin
  left; out('VTITLE ');
  for k:=0 to font_start[0]-1 do out(xchr[vf[k]]);
  right;
  end
else bad_vf('Title is not a balanced ASCII string')
@.Title is not balanced@>

@ We can re-use some code by moving |fix_word| data to |tfm|, using the
fact that the design size has already been output.

@p procedure out_as_fix(@!x:integer);
var @!k:1..3;
begin if abs(x)>=@'100000000 then
  bad_vf('Oversize dimension has been reset to zero.');
@.Oversize dimension...@>
if x>=0 then tfm[design_size]:=0
else begin
  tfm[design_size]:=255; x:=x+@'100000000;
  end;
for k:=3 downto 1 do begin
  tfm[design_size+k]:=x mod 256; x:=x div 256;
  end;
out_fix(design_size);
end;

@ @<Do the local fonts@>=
for f:=0 to font_ptr-1 do begin
  left; out('MAPFONT D ',f:1); out_ln;
  @<Output the font area and name@>;
  for k:=0 to 11 do tfm[k]:=vf[font_start[f]+k];
  if tfm[0]+tfm[1]+tfm[2]+tfm[3]>0 then begin
    left; out('FONTCHECKSUM'); out_hex(0,4); right;
    end;
  left; out('FONTAT'); out_fix(4); right;
  left; out('FONTDSIZE'); out_fix(8); right; right;
  end

@ @<Output the font area and name@>=
a:=vf[font_start[f]+12]; l:=vf[font_start[f]+13];
if a>0 then
  if not string_balance(font_start[f]+14,a) then
    bad_vf('Improper font area will be ignored')
@.Improper font area@>
  else begin
    left; out('FONTAREA ');
    for k:=font_start[f]+14 to font_start[f]+a+13 do out(xchr[vf[k]]);
    right;
    end;
if (l=0)or not string_balance(font_start[f]+14+a,l) then
  bad_vf('Improper font name will be ignored')
@.Improper font name@>
else begin
  left; out('FONTNAME ');
  for k:=font_start[f]+14+a to font_start[f]+a+l+13 do out(xchr[vf[k]]);
  right;
  end

@ Now we get to the interesting part of \.{VF} output, where \.{DVI}
commands are translated into symbolic form. The \.{VPL} language is a subset
of \.{DVI}, so we sometimes need to output semantic equivalents of
the commands instead of producing a literal translation. This causes a
small but tolerable loss of efficiency. We need to simulate the stack
used by \.{DVI}-reading software.

@<Glob...@>=
@!top:0..max_stack; {\.{DVI} stack pointer}
@!wstack,@!xstack,@!ystack,@!zstack:array[0..max_stack] of integer;
 {stacked values of \.{DVI} registers |w|, |x|, |y|, |z|}
@!vf_limit:0..vf_size; {the current packet ends here}
@!o:byte; {the current opcode}

@ @<Do the packet for character |c|@>=
if packet_start[c]=vf_size then
  bad_vf('Missing packet for character ',c:1)
@.Missing packet@>
else begin
  left; out('MAP'); out_ln;
  top:=0; wstack[0]:=0; xstack[0]:=0; ystack[0]:=0; zstack[0]:=0;
  vf_ptr:=packet_start[c]; vf_limit:=packet_end[c]+1; f:=0;
  while vf_ptr<vf_limit do begin
    o:=vf[vf_ptr]; incr(vf_ptr);
    case o of
    @<Cases of \.{DVI} instructions that can appear in character packets@>@;
    improper_DVI_for_VF: bad_vf('Illegal DVI code ',o:1,' will be ignored');
    end; {there are no other cases}
    end;
  if top>0 then begin
    bad_vf('More pushes than pops!');
@.More pushes than pops@>
    repeat out('(POP)'); decr(top);@+until top=0;
    end;
  right;
  end

@ A procedure called |get_bytes| helps fetch the parameters of \.{DVI} commands.

@p function get_bytes(@!k:integer;@!signed:boolean):integer;
var @!a:integer; {accumulator}
begin if vf_ptr+k>vf_limit then begin
  bad_vf('Packet ended prematurely'); k:=vf_limit-vf_ptr;
  end;
a:=vf[vf_ptr];
if (k=4) or signed then
  if a>=128 then a:=a-256;
incr(vf_ptr);
while k>1 do begin
  a:=a*256+vf[vf_ptr]; incr(vf_ptr); decr(k);
  end;
get_bytes:=a;
end;

@ Let's look at the simplest cases first, in order to get some experience.

@d four_cases(#)==#,#+1,#+2,#+3
@d eight_cases(#)==four_cases(#),four_cases(#+4)
@d sixteen_cases(#)==eight_cases(#),eight_cases(#+8)
@d thirty_two_cases(#)==sixteen_cases(#),sixteen_cases(#+16)
@d sixty_four_cases(#)==thirty_two_cases(#),thirty_two_cases(#+32)

@<Cases...@>=
nop:do_nothing;
push:begin if top=max_stack then
    begin print_ln('Stack overflow!'); goto final_end;
@.Stack overflow@>
    end;
  incr(top); wstack[top]:=wstack[top-1]; xstack[top]:=xstack[top-1];
  ystack[top]:=ystack[top-1]; zstack[top]:=zstack[top-1]; out('(PUSH)');
  out_ln;
  end;                            
pop:if top=0 then bad_vf('More pops than pushes!')
@.More pops than pushes@>
  else begin decr(top); out('(POP)'); out_ln;
    end;
set_rule,put_rule:begin if o=put_rule then out('(PUSH)');
  left; out('SETRULE'); out_as_fix(get_bytes(4,true));
  out_as_fix(get_bytes(4,true));
  if o=put_rule then out(')(POP');
  right;
  end;

@ Horizontal and vertical motions become \.{RIGHT} and \.{DOWN} in \.{VPL}
lingo.

@<Cases...@>=
four_cases(right1):begin out('(MOVERIGHT');
  out_as_fix(get_bytes(o-right1+1,true));
  out(')'); out_ln;@+end;
w0,four_cases(w1):begin if o<>w0 then wstack[top]:=get_bytes(o-w1+1,true);
  out('(MOVERIGHT'); out_as_fix(wstack[top]); out(')'); out_ln;@+end;
x0,four_cases(x1):begin if o<>x0 then xstack[top]:=get_bytes(o-x1+1,true);
  out('(MOVERIGHT'); out_as_fix(xstack[top]); out(')'); out_ln;@+end;
four_cases(down1):begin out('(MOVEDOWN'); out_as_fix(get_bytes(o-down1+1,true));
  out(')'); out_ln;@+end;
y0,four_cases(y1):begin if o<>y0 then ystack[top]:=get_bytes(o-y1+1,true);
  out('(MOVEDOWN'); out_as_fix(ystack[top]); out(')'); out_ln;@+end;
z0,four_cases(z1):begin if o<>z0 then zstack[top]:=get_bytes(o-z1+1,true);
  out('(MOVEDOWN'); out_as_fix(zstack[top]); out(')'); out_ln;@+end;

@ Variable |f| always refers to the current font. If |f=font_ptr|, it's
a font that hasn't been defined (so its characters will be ignored).

@<Cases...@>=
sixty_four_cases(fnt_num_0),four_cases(fnt1):begin f:=0;
  if o>=fnt1 then font_number[font_ptr]:=get_bytes(o-fnt1+1,false)
  else font_number[font_ptr]:=o-fnt_num_0;
  while font_number[f]<>font_number[font_ptr] do incr(f);
  if f=font_ptr then bad_vf('Undeclared font selected')
@.Undeclared font selected@>
  else begin out('(SELECTFONT D ',f:1,')'); out_ln;
    end;
  end;

@ Before we typeset a character we make sure that it exists.

@<Cases...@>=
sixty_four_cases(set_char_0),sixty_four_cases(set_char_0+64),
 four_cases(set1),four_cases(put1):begin if o>=set1 then
    if o>=put1 then c:=get_bytes(o-put1+1,false)
    else c:=get_bytes(o-set1+1,false)
  else c:=o;
  if f=font_ptr then
    bad_vf('Character ',c:1,' in undeclared font will be ignored')
@.Character...will be ignored@>
  else begin vf[font_start[f+1]-1]:=c; {store |c| in the ``hole'' we left}
    k:=font_chars[f];@+while vf[k]<>c do incr(k);
    if k=font_start[f+1]-1 then
      bad_vf('Character ',c:1,' in font ',f:1,' will be ignored')
    else begin if o>=put1 then out('(PUSH)');
      left; out('SETCHAR'); out_char(c);
      if o>=put1 then out(')(POP');
      right;
      end;
    end;
  end;

@ The ``special'' commands are the only ones remaining to be dealt with.
We use a hexadecimal
output in the general case, if a simple string would be inadequate.

@d vf_out_hex(#)==begin a:=#;
    if a<10 then out(a:1)
    else out(xchr[a-10+"A"]);
    end

@<Cases...@>=
four_cases(xxx1):begin k:=get_bytes(o-xxx1+1,false);
  if k<0 then bad_vf('String of negative length!')
  else begin left;
    if k+vf_ptr>vf_limit then
      begin bad_vf('Special command truncated to packet length');
      k:=vf_limit-vf_ptr;
      end;
    if (k>64)or not string_balance(vf_ptr,k) then
      begin out('SPECIALHEX ');
      while k>0 do
        begin if k mod 32=0 then out_ln
        else if k mod 4=0 then out(' ');
        vf_out_hex(vf[vf_ptr] div 16); vf_out_hex(vf[vf_ptr] mod 16);
        incr(vf_ptr); decr(k);
        end;
      end
    else begin out('SPECIAL ');
      while k>0 do
        begin out(xchr[vf[vf_ptr]]); incr(vf_ptr); decr(k);
        end;
      end;
    right;
    end;
  end;

@* The main program.
The routines sketched out so far need to be packaged into separate procedures,
on some systems, since some \PASCAL\ compilers place a strict limit on the
size of a routine. The packaging is done here in an attempt to avoid some
system-dependent changes.

First come the |vf_input| and |organize| procedures, which read the input data
and get ready for subsequent events. If something goes wrong, the routines
return |false|.

@p function vf_input:boolean;
label final_end, exit;
var vf_ptr:0..vf_size; {an index into |vf|}
@!k:integer; {all-purpose index}
@!c:integer; {character code}
begin @<Read the whole \.{VF} file@>;
vf_input:=true; return;
final_end: vf_input:=false;
exit: end;
@#
function organize:boolean;
label final_end, exit;
var tfm_ptr:index; {an index into |tfm|}
begin @<Read the whole font metric file@>;
@<Set subfile sizes |lh|, |bc|, \dots, |np|@>;
@<Compute the base addresses@>;
organize:=vf_input; return;
final_end: organize:=false;
exit: end;

@ Next we do the simple things.

@p procedure do_simple_things;
var i:0..@'77777; {an index to words of a subfile}
@!f:0..vf_size; {local font number}
@!k:integer; {all-purpose index}
begin @<Do the virtual font title@>;
@<Do the header@>;
@<Do the parameters@>;
@<Do the ivalue parameters@>;@/
@<Do the fvalue parameters@>;@/
@<Do the rule parameters@>;@/
@<Do the glue parameters@>;@/
@<Do the penalty parameters@>;@/
@<Do the local fonts@>;
@<Check the |fix_word| entries@>;
end;

@ And then there's a routine for individual characters.

@p function do_map(@!c:integer):boolean;
label final_end,exit;
var @!k:integer;
@!f:0..vf_size; {current font number}
begin @<Do the packet for character |c|@>;
do_map:=true; return;
final_end: do_map:=false;
exit:end;
@#
function do_characters:boolean;
label final_end, exit;
var @!c:integer; {character being done}
@!k:index; {a random index}
@!ai:0..lig_size; {index into |activity|}
begin @<Do the characters@>;@/
do_characters:=true; return;
final_end: do_characters:=false;
exit:end;

@ Here is where \.{VFtoVP} begins and ends.
@p begin initialize;@/
if not organize then goto final_end;
do_simple_things;@/
@<Do the ligatures and kerns@>;
@<Check the extensible recipes@>;
if not do_characters then goto final_end;
print_ln('.');@/
if level<>0 then print_ln('This program isn''t working!');
@.This program isn't working@>
if not perfect then begin
  out('(COMMENT THE OFM AND/OR OVF FILE WAS BAD, ');
  out('SO THE DATA HAS BEEN CHANGED!)');
  end;
@.THE OFM AND/OR OVF FILE WAS BAD...@>
final_end:end.

@* System-dependent changes.
This section should be replaced, if necessary, by changes to the program
that are necessary to make \.{VFtoVP} work at a particular installation.
It is usually best to design your change file so that all changes to
previous sections preserve the section numbering; then everybody's version
will be consistent with the printed program. More extensive changes,
which introduce new sections, can be inserted here; then only the index
itself will get a new section number.
@^system dependencies@>

@* Index.
Pointers to error messages appear here together with the section numbers
where each ident\-i\-fier is used.