aboutsummaryrefslogtreecommitdiff
path: root/gas/expr.c
blob: 47e69332f9abd0897c02b444034a69bfcc33eb9a (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
/* expr.c -operands, expressions-
   Copyright (C) 1987, 90, 91, 92, 93, 94, 95, 96, 97, 1998
   Free Software Foundation, Inc.

   This file is part of GAS, the GNU Assembler.

   GAS is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2, or (at your option)
   any later version.

   GAS is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with GAS; see the file COPYING.  If not, write to the Free
   Software Foundation, 59 Temple Place - Suite 330, Boston, MA
   02111-1307, USA. */

/*
 * This is really a branch office of as-read.c. I split it out to clearly
 * distinguish the world of expressions from the world of statements.
 * (It also gives smaller files to re-compile.)
 * Here, "operand"s are of expressions, not instructions.
 */

#include <ctype.h>
#include <string.h>
#define min(a, b)       ((a) < (b) ? (a) : (b))

#include "as.h"
#include "obstack.h"

static void floating_constant PARAMS ((expressionS * expressionP));
static void integer_constant PARAMS ((int radix, expressionS * expressionP));
static void mri_char_constant PARAMS ((expressionS *));
static void current_location PARAMS ((expressionS *));
static void clean_up_expression PARAMS ((expressionS * expressionP));
static segT operand PARAMS ((expressionS *));
static operatorT operator PARAMS ((void));

extern const char EXP_CHARS[], FLT_CHARS[];

/* We keep a mapping of expression symbols to file positions, so that
   we can provide better error messages.  */

struct expr_symbol_line
{
  struct expr_symbol_line *next;
  symbolS *sym;
  char *file;
  unsigned int line;
};

static struct expr_symbol_line *expr_symbol_lines;

/* Build a dummy symbol to hold a complex expression.  This is how we
   build expressions up out of other expressions.  The symbol is put
   into the fake section expr_section.  */

symbolS *
make_expr_symbol (expressionP)
     expressionS *expressionP;
{
  const char *fake;
  symbolS *symbolP;
  struct expr_symbol_line *n;

  if (expressionP->X_op == O_symbol
      && expressionP->X_add_number == 0)
    return expressionP->X_add_symbol;

  fake = FAKE_LABEL_NAME;

  /* Putting constant symbols in absolute_section rather than
     expr_section is convenient for the old a.out code, for which
     S_GET_SEGMENT does not always retrieve the value put in by
     S_SET_SEGMENT.  */
  symbolP = symbol_create (fake,
			   (expressionP->X_op == O_constant
			    ? absolute_section
			    : expr_section),
			   0, &zero_address_frag);
  symbolP->sy_value = *expressionP;

  if (expressionP->X_op == O_constant)
    resolve_symbol_value (symbolP, 1);

  n = (struct expr_symbol_line *) xmalloc (sizeof *n);
  n->sym = symbolP;
  as_where (&n->file, &n->line);
  n->next = expr_symbol_lines;
  expr_symbol_lines = n;

  return symbolP;
}

/* Return the file and line number for an expr symbol.  Return
   non-zero if something was found, 0 if no information is known for
   the symbol.  */

int
expr_symbol_where (sym, pfile, pline)
     symbolS *sym;
     char **pfile;
     unsigned int *pline;
{
  register struct expr_symbol_line *l;

  for (l = expr_symbol_lines; l != NULL; l = l->next)
    {
      if (l->sym == sym)
	{
	  *pfile = l->file;
	  *pline = l->line;
	  return 1;
	}
    }

  return 0;
}

/* Utilities for building expressions.
   Since complex expressions are recorded as symbols for use in other
   expressions these return a symbolS * and not an expressionS *.
   These explicitly do not take an "add_number" argument.  */
/* ??? For completeness' sake one might want expr_build_symbol.
   It would just return its argument.  */

/* Build an expression for an unsigned constant.
   The corresponding one for signed constants is missing because
   there's currently no need for it.  One could add an unsigned_p flag
   but that seems more clumsy.  */

symbolS *
expr_build_uconstant (value)
     offsetT value;
{
  expressionS e;

  e.X_op = O_constant;
  e.X_add_number = value;
  e.X_unsigned = 1;
  return make_expr_symbol (&e);
}

/* Build an expression for OP s1.  */

symbolS *
expr_build_unary (op, s1)
     operatorT op;
     symbolS *s1;
{
  expressionS e;

  e.X_op = op;
  e.X_add_symbol = s1;
  e.X_add_number = 0;
  return make_expr_symbol (&e);
}

/* Build an expression for s1 OP s2.  */

symbolS *
expr_build_binary (op, s1, s2)
     operatorT op;
     symbolS *s1;
     symbolS *s2;
{
  expressionS e;

  e.X_op = op;
  e.X_add_symbol = s1;
  e.X_op_symbol = s2;
  e.X_add_number = 0;
  return make_expr_symbol (&e);
}

/*
 * Build any floating-point literal here.
 * Also build any bignum literal here.
 */

/* Seems atof_machine can backscan through generic_bignum and hit whatever
   happens to be loaded before it in memory.  And its way too complicated
   for me to fix right.  Thus a hack.  JF:  Just make generic_bignum bigger,
   and never write into the early words, thus they'll always be zero.
   I hate Dean's floating-point code.  Bleh.  */
LITTLENUM_TYPE generic_bignum[SIZE_OF_LARGE_NUMBER + 6];
FLONUM_TYPE generic_floating_point_number =
{
  &generic_bignum[6],		/* low (JF: Was 0) */
  &generic_bignum[SIZE_OF_LARGE_NUMBER + 6 - 1], /* high JF: (added +6) */
  0,				/* leader */
  0,				/* exponent */
  0				/* sign */
};
/* If nonzero, we've been asked to assemble nan, +inf or -inf */
int generic_floating_point_magic;

static void
floating_constant (expressionP)
     expressionS *expressionP;
{
  /* input_line_pointer->*/
  /* floating-point constant. */
  int error_code;

  error_code = atof_generic (&input_line_pointer, ".", EXP_CHARS,
			     &generic_floating_point_number);

  if (error_code)
    {
      if (error_code == ERROR_EXPONENT_OVERFLOW)
	{
	  as_bad ("bad floating-point constant: exponent overflow, probably assembling junk");
	}
      else
	{
	  as_bad ("bad floating-point constant: unknown error code=%d.", error_code);
	}
    }
  expressionP->X_op = O_big;
  /* input_line_pointer->just after constant, */
  /* which may point to whitespace. */
  expressionP->X_add_number = -1;
}

static valueT 
generic_bignum_to_int32 () 
{
  valueT number =
	   ((generic_bignum[1] & LITTLENUM_MASK) << LITTLENUM_NUMBER_OF_BITS)
	   | (generic_bignum[0] & LITTLENUM_MASK);
  number &= 0xffffffff;
  return number;
}

#ifdef BFD64
static valueT 
generic_bignum_to_int64 () 
{
  valueT number = 
	   ((((((((valueT) generic_bignum[3] & LITTLENUM_MASK)
		 << LITTLENUM_NUMBER_OF_BITS)
	        | ((valueT) generic_bignum[2] & LITTLENUM_MASK))
	       << LITTLENUM_NUMBER_OF_BITS)
	      | ((valueT) generic_bignum[1] & LITTLENUM_MASK))
	     << LITTLENUM_NUMBER_OF_BITS)
	    | ((valueT) generic_bignum[0] & LITTLENUM_MASK));
  return number;
}
#endif

static void
integer_constant (radix, expressionP)
     int radix;
     expressionS *expressionP;
{
  char *start;		/* start of number. */
  char *suffix = NULL;
  char c;
  valueT number;	/* offset or (absolute) value */
  short int digit;	/* value of next digit in current radix */
  short int maxdig = 0;/* highest permitted digit value. */
  int too_many_digits = 0;	/* if we see >= this number of */
  char *name;		/* points to name of symbol */
  symbolS *symbolP;	/* points to symbol */

  int small;			/* true if fits in 32 bits. */

  /* May be bignum, or may fit in 32 bits. */
  /* Most numbers fit into 32 bits, and we want this case to be fast.
     so we pretend it will fit into 32 bits.  If, after making up a 32
     bit number, we realise that we have scanned more digits than
     comfortably fit into 32 bits, we re-scan the digits coding them
     into a bignum.  For decimal and octal numbers we are
     conservative: Some numbers may be assumed bignums when in fact
     they do fit into 32 bits.  Numbers of any radix can have excess
     leading zeros: We strive to recognise this and cast them back
     into 32 bits.  We must check that the bignum really is more than
     32 bits, and change it back to a 32-bit number if it fits.  The
     number we are looking for is expected to be positive, but if it
     fits into 32 bits as an unsigned number, we let it be a 32-bit
     number.  The cavalier approach is for speed in ordinary cases. */
  /* This has been extended for 64 bits.  We blindly assume that if
     you're compiling in 64-bit mode, the target is a 64-bit machine.
     This should be cleaned up.  */

#ifdef BFD64
#define valuesize 64
#else /* includes non-bfd case, mostly */
#define valuesize 32
#endif

  if (flag_m68k_mri && radix == 0)
    {
      int flt = 0;

      /* In MRI mode, the number may have a suffix indicating the
         radix.  For that matter, it might actually be a floating
         point constant.  */
      for (suffix = input_line_pointer;
	   isalnum ((unsigned char) *suffix);
	   suffix++)
	{
	  if (*suffix == 'e' || *suffix == 'E')
	    flt = 1;
	}

      if (suffix == input_line_pointer)
	{
	  radix = 10;
	  suffix = NULL;
	}
      else
	{
	  c = *--suffix;
	  if (islower ((unsigned char) c))
	    c = toupper (c);
	  if (c == 'B')
	    radix = 2;
	  else if (c == 'D')
	    radix = 10;
	  else if (c == 'O' || c == 'Q')
	    radix = 8;
	  else if (c == 'H')
	    radix = 16;
	  else if (suffix[1] == '.' || c == 'E' || flt)
	    {
	      floating_constant (expressionP);
	      return;
	    }
	  else
	    {
	      radix = 10;
	      suffix = NULL;
	    }
	}
    }

  switch (radix)
    {
    case 2:
      maxdig = 2;
      too_many_digits = valuesize + 1;
      break;
    case 8:
      maxdig = radix = 8;
      too_many_digits = (valuesize + 2) / 3 + 1;
      break;
    case 16:
      maxdig = radix = 16;
      too_many_digits = (valuesize + 3) / 4 + 1;
      break;
    case 10:
      maxdig = radix = 10;
      too_many_digits = (valuesize + 12) / 4; /* very rough */
    }
#undef valuesize
  start = input_line_pointer;
  c = *input_line_pointer++;
  for (number = 0;
       (digit = hex_value (c)) < maxdig;
       c = *input_line_pointer++)
    {
      number = number * radix + digit;
    }
  /* c contains character after number. */
  /* input_line_pointer->char after c. */
  small = (input_line_pointer - start - 1) < too_many_digits;

  if (radix == 16 && c == '_') 
    {
      /* This is literal of the form 0x333_0_12345678_1.
         This example is equivalent to 0x00000333000000001234567800000001.  */

      int num_little_digits = 0;
      int i;
      input_line_pointer = start;	/*->1st digit. */

      know (LITTLENUM_NUMBER_OF_BITS == 16);

      for (c = '_'; c == '_'; num_little_digits+=2)
	{

	  /* Convert one 64-bit word. */
	  int ndigit = 0; 
	  number = 0;
	  for (c = *input_line_pointer++;
	       (digit = hex_value (c)) < maxdig;
	       c = *(input_line_pointer++))
	    {
	      number = number * radix + digit;
	      ndigit++;
	    }

	  /* Check for 8 digit per word max.  */
	  if (ndigit > 8) 
	    as_bad ("An bignum with underscores may not have more than 8 hex digits in any word.");

	  /* Add this chunk to the bignum.  Shift things down 2 little digits.*/
	  know (LITTLENUM_NUMBER_OF_BITS == 16);
	  for (i = min (num_little_digits + 1, SIZE_OF_LARGE_NUMBER - 1); i >= 2; i--)
	    generic_bignum[i] = generic_bignum[i-2];

	  /* Add the new digits as the least significant new ones. */
	  generic_bignum[0] = number & 0xffffffff;
	  generic_bignum[1] = number >> 16;
	}

      /* Again, c is char after number, input_line_pointer->after c. */

      if (num_little_digits > SIZE_OF_LARGE_NUMBER - 1)
	num_little_digits = SIZE_OF_LARGE_NUMBER - 1;

      assert (num_little_digits >= 4);

      if (num_little_digits != 8)
	as_bad ("A bignum with underscores must have exactly 4 words.");

      /* We might have some leading zeros.  These can be trimmed to give
       * us a change to fit this constant into a small number.
       */
      while (generic_bignum[num_little_digits-1] == 0 && num_little_digits > 1)
	num_little_digits--;
	
      if (num_little_digits <= 2)
	{
	  /* will fit into 32 bits. */
	  number = generic_bignum_to_int32 ();
	  small = 1;
	}
#ifdef BFD64
      else if (num_little_digits <= 4)
	{
	  /* Will fit into 64 bits.  */
	  number = generic_bignum_to_int64 ();
	  small = 1;
	}
#endif
      else
	{
	  small = 0;
	  number = num_little_digits; /* number of littlenums in the bignum. */
	}
    }
  else if (!small)
    {
      /*
       * we saw a lot of digits. manufacture a bignum the hard way.
       */
      LITTLENUM_TYPE *leader;	/*->high order littlenum of the bignum. */
      LITTLENUM_TYPE *pointer;	/*->littlenum we are frobbing now. */
      long carry;

      leader = generic_bignum;
      generic_bignum[0] = 0;
      generic_bignum[1] = 0;
      generic_bignum[2] = 0;
      generic_bignum[3] = 0;
      input_line_pointer = start;	/*->1st digit. */
      c = *input_line_pointer++;
      for (;
	   (carry = hex_value (c)) < maxdig;
	   c = *input_line_pointer++)
	{
	  for (pointer = generic_bignum;
	       pointer <= leader;
	       pointer++)
	    {
	      long work;

	      work = carry + radix * *pointer;
	      *pointer = work & LITTLENUM_MASK;
	      carry = work >> LITTLENUM_NUMBER_OF_BITS;
	    }
	  if (carry)
	    {
	      if (leader < generic_bignum + SIZE_OF_LARGE_NUMBER - 1)
		{
		  /* room to grow a longer bignum. */
		  *++leader = carry;
		}
	    }
	}
      /* again, c is char after number, */
      /* input_line_pointer->after c. */
      know (LITTLENUM_NUMBER_OF_BITS == 16);
      if (leader < generic_bignum + 2)
	{
	  /* will fit into 32 bits. */
	  number = generic_bignum_to_int32 ();
	  small = 1;
	}
#ifdef BFD64
      else if (leader < generic_bignum + 4)
	{
	  /* Will fit into 64 bits.  */
	  number = generic_bignum_to_int64 ();
	  small = 1;
	}
#endif
      else
	{
	  number = leader - generic_bignum + 1;	/* number of littlenums in the bignum. */
	}
    }

  if (flag_m68k_mri && suffix != NULL && input_line_pointer - 1 == suffix)
    c = *input_line_pointer++;

  if (small)
    {
      /*
       * here with number, in correct radix. c is the next char.
       * note that unlike un*x, we allow "011f" "0x9f" to
       * both mean the same as the (conventional) "9f". this is simply easier
       * than checking for strict canonical form. syntax sux!
       */

      if (LOCAL_LABELS_FB && c == 'b')
	{
	  /*
	   * backward ref to local label.
	   * because it is backward, expect it to be defined.
	   */
	  /* Construct a local label.  */
	  name = fb_label_name ((int) number, 0);

	  /* seen before, or symbol is defined: ok */
	  symbolP = symbol_find (name);
	  if ((symbolP != NULL) && (S_IS_DEFINED (symbolP)))
	    {
	      /* local labels are never absolute. don't waste time
		 checking absoluteness. */
	      know (SEG_NORMAL (S_GET_SEGMENT (symbolP)));

	      expressionP->X_op = O_symbol;
	      expressionP->X_add_symbol = symbolP;
	    }
	  else
	    {
	      /* either not seen or not defined. */
	      /* @@ Should print out the original string instead of
		 the parsed number.  */
	      as_bad ("backw. ref to unknown label \"%d:\", 0 assumed.",
		      (int) number);
	      expressionP->X_op = O_constant;
	    }

	  expressionP->X_add_number = 0;
	}			/* case 'b' */
      else if (LOCAL_LABELS_FB && c == 'f')
	{
	  /*
	   * forward reference. expect symbol to be undefined or
	   * unknown. undefined: seen it before. unknown: never seen
	   * it before.
	   * construct a local label name, then an undefined symbol.
	   * don't create a xseg frag for it: caller may do that.
	   * just return it as never seen before.
	   */
	  name = fb_label_name ((int) number, 1);
	  symbolP = symbol_find_or_make (name);
	  /* we have no need to check symbol properties. */
#ifndef many_segments
	  /* since "know" puts its arg into a "string", we
	     can't have newlines in the argument.  */
	  know (S_GET_SEGMENT (symbolP) == undefined_section || S_GET_SEGMENT (symbolP) == text_section || S_GET_SEGMENT (symbolP) == data_section);
#endif
	  expressionP->X_op = O_symbol;
	  expressionP->X_add_symbol = symbolP;
	  expressionP->X_add_number = 0;
	}			/* case 'f' */
      else if (LOCAL_LABELS_DOLLAR && c == '$')
	{
	  /* If the dollar label is *currently* defined, then this is just
	     another reference to it.  If it is not *currently* defined,
	     then this is a fresh instantiation of that number, so create
	     it.  */

	  if (dollar_label_defined ((long) number))
	    {
	      name = dollar_label_name ((long) number, 0);
	      symbolP = symbol_find (name);
	      know (symbolP != NULL);
	    }
	  else
	    {
	      name = dollar_label_name ((long) number, 1);
	      symbolP = symbol_find_or_make (name);
	    }

	  expressionP->X_op = O_symbol;
	  expressionP->X_add_symbol = symbolP;
	  expressionP->X_add_number = 0;
	}			/* case '$' */
      else
	{
	  expressionP->X_op = O_constant;
#ifdef TARGET_WORD_SIZE
	  /* Sign extend NUMBER.  */
	  number |= (-(number >> (TARGET_WORD_SIZE - 1))) << (TARGET_WORD_SIZE - 1);
#endif
	  expressionP->X_add_number = number;
	  input_line_pointer--;	/* restore following character. */
	}			/* really just a number */
    }
  else
    {
      /* not a small number */
      expressionP->X_op = O_big;
      expressionP->X_add_number = number;	/* number of littlenums */
      input_line_pointer--;	/*->char following number. */
    }
}

/* Parse an MRI multi character constant.  */

static void
mri_char_constant (expressionP)
     expressionS *expressionP;
{
  int i;

  if (*input_line_pointer == '\''
      && input_line_pointer[1] != '\'')
    {
      expressionP->X_op = O_constant;
      expressionP->X_add_number = 0;
      return;
    }

  /* In order to get the correct byte ordering, we must build the
     number in reverse.  */
  for (i = SIZE_OF_LARGE_NUMBER - 1; i >= 0; i--)
    {
      int j;

      generic_bignum[i] = 0;
      for (j = 0; j < CHARS_PER_LITTLENUM; j++)
	{
	  if (*input_line_pointer == '\'')
	    {
	      if (input_line_pointer[1] != '\'')
		break;
	      ++input_line_pointer;
	    }
	  generic_bignum[i] <<= 8;
	  generic_bignum[i] += *input_line_pointer;
	  ++input_line_pointer;
	}

      if (i < SIZE_OF_LARGE_NUMBER - 1)
	{
	  /* If there is more than one littlenum, left justify the
             last one to make it match the earlier ones.  If there is
             only one, we can just use the value directly.  */
	  for (; j < CHARS_PER_LITTLENUM; j++)
	    generic_bignum[i] <<= 8;
	}

      if (*input_line_pointer == '\''
	  && input_line_pointer[1] != '\'')
	break;
    }

  if (i < 0)
    {
      as_bad ("Character constant too large");
      i = 0;
    }

  if (i > 0)
    {
      int c;
      int j;

      c = SIZE_OF_LARGE_NUMBER - i;
      for (j = 0; j < c; j++)
	generic_bignum[j] = generic_bignum[i + j];
      i = c;
    }

  know (LITTLENUM_NUMBER_OF_BITS == 16);
  if (i > 2)
    {
      expressionP->X_op = O_big;
      expressionP->X_add_number = i;
    }
  else
    {
      expressionP->X_op = O_constant;
      if (i < 2)
	expressionP->X_add_number = generic_bignum[0] & LITTLENUM_MASK;
      else
	expressionP->X_add_number =
	  (((generic_bignum[1] & LITTLENUM_MASK)
	    << LITTLENUM_NUMBER_OF_BITS)
	   | (generic_bignum[0] & LITTLENUM_MASK));
    }

  /* Skip the final closing quote.  */
  ++input_line_pointer;
}

/* Return an expression representing the current location.  This
   handles the magic symbol `.'.  */

static void
current_location (expressionp)
     expressionS *expressionp;
{
  if (now_seg == absolute_section)
    {
      expressionp->X_op = O_constant;
      expressionp->X_add_number = abs_section_offset;
    }
  else
    {
      symbolS *symbolp;

      symbolp = symbol_new (FAKE_LABEL_NAME, now_seg,
			    (valueT) frag_now_fix (),
			    frag_now);
      expressionp->X_op = O_symbol;
      expressionp->X_add_symbol = symbolp;
      expressionp->X_add_number = 0;
    }
}

/*
 * Summary of operand().
 *
 * in:	Input_line_pointer points to 1st char of operand, which may
 *	be a space.
 *
 * out:	A expressionS.
 *	The operand may have been empty: in this case X_op == O_absent.
 *	Input_line_pointer->(next non-blank) char after operand.
 */

static segT
operand (expressionP)
     expressionS *expressionP;
{
  char c;
  symbolS *symbolP;	/* points to symbol */
  char *name;		/* points to name of symbol */
  segT segment;

  /* All integers are regarded as unsigned unless they are negated.
     This is because the only thing which cares whether a number is
     unsigned is the code in emit_expr which extends constants into
     bignums.  It should only sign extend negative numbers, so that
     something like ``.quad 0x80000000'' is not sign extended even
     though it appears negative if valueT is 32 bits.  */
  expressionP->X_unsigned = 1;

  /* digits, assume it is a bignum. */

  SKIP_WHITESPACE ();		/* leading whitespace is part of operand. */
  c = *input_line_pointer++;	/* input_line_pointer->past char in c. */

  switch (c)
    {
    case '1':
    case '2':
    case '3':
    case '4':
    case '5':
    case '6':
    case '7':
    case '8':
    case '9':
      input_line_pointer--;

      integer_constant (flag_m68k_mri ? 0 : 10, expressionP);
      break;

    case '0':
      /* non-decimal radix */

      if (flag_m68k_mri)
	{
	  char *s;

	  /* Check for a hex constant.  */
	  for (s = input_line_pointer; hex_p (*s); s++)
	    ;
	  if (*s == 'h' || *s == 'H')
	    {
	      --input_line_pointer;
	      integer_constant (0, expressionP);
	      break;
	    }
	}

      c = *input_line_pointer;
      switch (c)
	{
	case 'o':
	case 'O':
	case 'q':
	case 'Q':
	case '8':
	case '9':
	  if (flag_m68k_mri)
	    {
	      integer_constant (0, expressionP);
	      break;
	    }
	  /* Fall through.  */
	default:
	default_case:
	  if (c && strchr (FLT_CHARS, c))
	    {
	      input_line_pointer++;
	      floating_constant (expressionP);
	      expressionP->X_add_number =
		- (isupper ((unsigned char) c) ? tolower (c) : c);
	    }
	  else
	    {
	      /* The string was only zero */
	      expressionP->X_op = O_constant;
	      expressionP->X_add_number = 0;
	    }

	  break;

	case 'x':
	case 'X':
	  if (flag_m68k_mri)
	    goto default_case;
	  input_line_pointer++;
	  integer_constant (16, expressionP);
	  break;

	case 'b':
	  if (LOCAL_LABELS_FB && ! flag_m68k_mri)
	    {
	      /* This code used to check for '+' and '-' here, and, in
		 some conditions, fall through to call
		 integer_constant.  However, that didn't make sense,
		 as integer_constant only accepts digits.  */
	      /* Some of our code elsewhere does permit digits greater
		 than the expected base; for consistency, do the same
		 here.  */
	      if (input_line_pointer[1] < '0'
		  || input_line_pointer[1] > '9')
		{
		  /* Parse this as a back reference to label 0.  */
		  input_line_pointer--;
		  integer_constant (10, expressionP);
		  break;
		}
	      /* Otherwise, parse this as a binary number.  */
	    }
	  /* Fall through.  */
	case 'B':
	  input_line_pointer++;
	  if (flag_m68k_mri)
	    goto default_case;
	  integer_constant (2, expressionP);
	  break;

	case '0':
	case '1':
	case '2':
	case '3':
	case '4':
	case '5':
	case '6':
	case '7':
	  integer_constant (flag_m68k_mri ? 0 : 8, expressionP);
	  break;

	case 'f':
	  if (LOCAL_LABELS_FB)
	    {
	      /* If it says "0f" and it could possibly be a floating point
		 number, make it one.  Otherwise, make it a local label,
		 and try to deal with parsing the rest later.  */
	      if (!input_line_pointer[1]
		  || (is_end_of_line[0xff & input_line_pointer[1]]))
		goto is_0f_label;
	      {
		char *cp = input_line_pointer + 1;
		int r = atof_generic (&cp, ".", EXP_CHARS,
				      &generic_floating_point_number);
		switch (r)
		  {
		  case 0:
		  case ERROR_EXPONENT_OVERFLOW:
		    if (*cp == 'f' || *cp == 'b')
		      /* looks like a difference expression */
		      goto is_0f_label;
		    else
		      goto is_0f_float;
		  default:
		    as_fatal ("expr.c(operand): bad atof_generic return val %d",
			      r);
		  }
	      }

	      /* Okay, now we've sorted it out.  We resume at one of these
		 two labels, depending on what we've decided we're probably
		 looking at.  */
	    is_0f_label:
	      input_line_pointer--;
	      integer_constant (10, expressionP);
	      break;

	    is_0f_float:
	      /* fall through */
	      ;
	    }

	case 'd':
	case 'D':
	  if (flag_m68k_mri)
	    {
	      integer_constant (0, expressionP);
	      break;
	    }
	  /* Fall through.  */
	case 'F':
	case 'r':
	case 'e':
	case 'E':
	case 'g':
	case 'G':
	  input_line_pointer++;
	  floating_constant (expressionP);
	  expressionP->X_add_number =
	    - (isupper ((unsigned char) c) ? tolower (c) : c);
	  break;

	case '$':
	  if (LOCAL_LABELS_DOLLAR)
	    {
	      integer_constant (10, expressionP);
	      break;
	    }
	  else
	    goto default_case;
	}

      break;

    case '(':
    case '[':
      /* didn't begin with digit & not a name */
      segment = expression (expressionP);
      /* Expression() will pass trailing whitespace */
      if ((c == '(' && *input_line_pointer++ != ')')
	  || (c == '[' && *input_line_pointer++ != ']'))
	{
	  as_bad ("Missing ')' assumed");
	  input_line_pointer--;
	}
      SKIP_WHITESPACE ();
      /* here with input_line_pointer->char after "(...)" */
      return segment;

    case 'E':
      if (! flag_m68k_mri || *input_line_pointer != '\'')
	goto de_fault;
      as_bad ("EBCDIC constants are not supported");
      /* Fall through.  */
    case 'A':
      if (! flag_m68k_mri || *input_line_pointer != '\'')
	goto de_fault;
      ++input_line_pointer;
      /* Fall through.  */
    case '\'':
      if (! flag_m68k_mri)
	{
	  /* Warning: to conform to other people's assemblers NO
	     ESCAPEMENT is permitted for a single quote. The next
	     character, parity errors and all, is taken as the value
	     of the operand. VERY KINKY.  */
	  expressionP->X_op = O_constant;
	  expressionP->X_add_number = *input_line_pointer++;
	  break;
	}

      mri_char_constant (expressionP);
      break;

    case '+':
      (void) operand (expressionP);
      break;

    case '"':
      /* Double quote is the bitwise not operator in MRI mode.  */
      if (! flag_m68k_mri)
	goto de_fault;
      /* Fall through.  */
    case '~':
      /* ~ is permitted to start a label on the Delta.  */
      if (is_name_beginner (c))
	goto isname;
    case '!':
    case '-':
      {
	operand (expressionP);
	if (expressionP->X_op == O_constant)
	  {
	    /* input_line_pointer -> char after operand */
	    if (c == '-')
	      {
		expressionP->X_add_number = - expressionP->X_add_number;
		/* Notice: '-' may overflow: no warning is given. This is
		   compatible with other people's assemblers. Sigh.  */
		expressionP->X_unsigned = 0;
	      }
	    else if (c == '~' || c == '"')
	      expressionP->X_add_number = ~ expressionP->X_add_number;
	    else
	      expressionP->X_add_number = ! expressionP->X_add_number;
	  }
	else if (expressionP->X_op != O_illegal
		 && expressionP->X_op != O_absent)
	  {
	    expressionP->X_add_symbol = make_expr_symbol (expressionP);
	    if (c == '-')
	      expressionP->X_op = O_uminus;
	    else if (c == '~' || c == '"')
	      expressionP->X_op = O_bit_not;
	    else
	      expressionP->X_op = O_logical_not;
	    expressionP->X_add_number = 0;
	  }
	else
	  as_warn ("Unary operator %c ignored because bad operand follows",
		   c);
      }
      break;

    case '$':
      /* $ is the program counter when in MRI mode, or when DOLLAR_DOT
         is defined.  */
#ifndef DOLLAR_DOT
      if (! flag_m68k_mri)
	goto de_fault;
#endif
      if (flag_m68k_mri && hex_p (*input_line_pointer))
	{
	  /* In MRI mode, $ is also used as the prefix for a
             hexadecimal constant.  */
	  integer_constant (16, expressionP);
	  break;
	}

      if (is_part_of_name (*input_line_pointer))
	goto isname;

      current_location (expressionP);
      break;

    case '.':
      if (!is_part_of_name (*input_line_pointer))
	{
	  current_location (expressionP);
	  break;
	}
      else if ((strncasecmp (input_line_pointer, "startof.", 8) == 0
		&& ! is_part_of_name (input_line_pointer[8]))
	       || (strncasecmp (input_line_pointer, "sizeof.", 7) == 0
		   && ! is_part_of_name (input_line_pointer[7])))
	{
	  int start;

	  start = (input_line_pointer[1] == 't'
		   || input_line_pointer[1] == 'T');
	  input_line_pointer += start ? 8 : 7;
	  SKIP_WHITESPACE ();
	  if (*input_line_pointer != '(')
	    as_bad ("syntax error in .startof. or .sizeof.");
	  else
	    {
	      char *buf;

	      ++input_line_pointer;
	      SKIP_WHITESPACE ();
	      name = input_line_pointer;
	      c = get_symbol_end ();

	      buf = (char *) xmalloc (strlen (name) + 10);
	      if (start)
		sprintf (buf, ".startof.%s", name);
	      else
		sprintf (buf, ".sizeof.%s", name);
	      symbolP = symbol_make (buf);
	      free (buf);

	      expressionP->X_op = O_symbol;
	      expressionP->X_add_symbol = symbolP;
	      expressionP->X_add_number = 0;

	      *input_line_pointer = c;
	      SKIP_WHITESPACE ();
	      if (*input_line_pointer != ')')
		as_bad ("syntax error in .startof. or .sizeof.");
	      else
		++input_line_pointer;
	    }
	  break;
	}
      else
	{
	  goto isname;
	}
    case ',':
    case '\n':
    case '\0':
    eol:
      /* can't imagine any other kind of operand */
      expressionP->X_op = O_absent;
      input_line_pointer--;
      break;

    case '%':
      if (! flag_m68k_mri)
	goto de_fault;
      integer_constant (2, expressionP);
      break;

    case '@':
      if (! flag_m68k_mri)
	goto de_fault;
      integer_constant (8, expressionP);
      break;

    case ':':
      if (! flag_m68k_mri)
	goto de_fault;

      /* In MRI mode, this is a floating point constant represented
         using hexadecimal digits.  */

      ++input_line_pointer;
      integer_constant (16, expressionP);
      break;

    case '*':
      if (! flag_m68k_mri || is_part_of_name (*input_line_pointer))
	goto de_fault;

      current_location (expressionP);
      break;

    default:
    de_fault:
      if (is_end_of_line[(unsigned char) c])
	goto eol;
      if (is_name_beginner (c))	/* here if did not begin with a digit */
	{
	  /*
	   * Identifier begins here.
	   * This is kludged for speed, so code is repeated.
	   */
	isname:
	  name = --input_line_pointer;
	  c = get_symbol_end ();

#ifdef md_parse_name
	  /* This is a hook for the backend to parse certain names
             specially in certain contexts.  If a name always has a
             specific value, it can often be handled by simply
             entering it in the symbol table.  */
	  if (md_parse_name (name, expressionP))
	    {
	      *input_line_pointer = c;
	      break;
	    }
#endif

#ifdef TC_I960
	  /* The MRI i960 assembler permits
	         lda sizeof code,g13
	     FIXME: This should use md_parse_name.  */
	  if (flag_mri
	      && (strcasecmp (name, "sizeof") == 0
		  || strcasecmp (name, "startof") == 0))
	    {
	      int start;
	      char *buf;

	      start = (name[1] == 't'
		       || name[1] == 'T');

	      *input_line_pointer = c;
	      SKIP_WHITESPACE ();

	      name = input_line_pointer;
	      c = get_symbol_end ();

	      buf = (char *) xmalloc (strlen (name) + 10);
	      if (start)
		sprintf (buf, ".startof.%s", name);
	      else
		sprintf (buf, ".sizeof.%s", name);
	      symbolP = symbol_make (buf);
	      free (buf);

	      expressionP->X_op = O_symbol;
	      expressionP->X_add_symbol = symbolP;
	      expressionP->X_add_number = 0;

	      *input_line_pointer = c;
	      SKIP_WHITESPACE ();

	      break;
	    }	      
#endif

	  symbolP = symbol_find_or_make (name);

	  /* If we have an absolute symbol or a reg, then we know its
	     value now.  */
	  segment = S_GET_SEGMENT (symbolP);
	  if (segment == absolute_section)
	    {
	      expressionP->X_op = O_constant;
	      expressionP->X_add_number = S_GET_VALUE (symbolP);
	    }
	  else if (segment == reg_section)
	    {
	      expressionP->X_op = O_register;
	      expressionP->X_add_number = S_GET_VALUE (symbolP);
	    }
	  else
	    {
	      expressionP->X_op = O_symbol;
	      expressionP->X_add_symbol = symbolP;
	      expressionP->X_add_number = 0;
	    }
	  *input_line_pointer = c;
	}
      else
	{
	  /* Let the target try to parse it.  Success is indicated by changing
	     the X_op field to something other than O_absent and pointing
	     input_line_pointer passed the expression.  If it can't parse the
	     expression, X_op and input_line_pointer should be unchanged.  */
	  expressionP->X_op = O_absent;
	  --input_line_pointer;
	  md_operand (expressionP);
	  if (expressionP->X_op == O_absent)
	    {
	      ++input_line_pointer;
	      as_bad ("Bad expression");
	      expressionP->X_op = O_constant;
	      expressionP->X_add_number = 0;
	    }
	}
      break;
    }

  /*
   * It is more 'efficient' to clean up the expressionS when they are created.
   * Doing it here saves lines of code.
   */
  clean_up_expression (expressionP);
  SKIP_WHITESPACE ();		/*->1st char after operand. */
  know (*input_line_pointer != ' ');

  /* The PA port needs this information.  */
  if (expressionP->X_add_symbol)
    expressionP->X_add_symbol->sy_used = 1;

  switch (expressionP->X_op)
    {
    default:
      return absolute_section;
    case O_symbol:
      return S_GET_SEGMENT (expressionP->X_add_symbol);
    case O_register:
      return reg_section;
    }
}				/* operand() */

/* Internal. Simplify a struct expression for use by expr() */

/*
 * In:	address of a expressionS.
 *	The X_op field of the expressionS may only take certain values.
 *	Elsewise we waste time special-case testing. Sigh. Ditto SEG_ABSENT.
 * Out:	expressionS may have been modified:
 *	'foo-foo' symbol references cancelled to 0,
 *		which changes X_op from O_subtract to O_constant.
 *	Unused fields zeroed to help expr().
 */

static void
clean_up_expression (expressionP)
     expressionS *expressionP;
{
  switch (expressionP->X_op)
    {
    case O_illegal:
    case O_absent:
      expressionP->X_add_number = 0;
      /* Fall through.  */
    case O_big:
    case O_constant:
    case O_register:
      expressionP->X_add_symbol = NULL;
      /* Fall through.  */
    case O_symbol:
    case O_uminus:
    case O_bit_not:
      expressionP->X_op_symbol = NULL;
      break;
    case O_subtract:
      if (expressionP->X_op_symbol == expressionP->X_add_symbol
	  || ((expressionP->X_op_symbol->sy_frag
	       == expressionP->X_add_symbol->sy_frag)
	      && SEG_NORMAL (S_GET_SEGMENT (expressionP->X_add_symbol))
	      && (S_GET_VALUE (expressionP->X_op_symbol)
		  == S_GET_VALUE (expressionP->X_add_symbol))))
	{
	  addressT diff = (S_GET_VALUE (expressionP->X_add_symbol)
			   - S_GET_VALUE (expressionP->X_op_symbol));

	  expressionP->X_op = O_constant;
	  expressionP->X_add_symbol = NULL;
	  expressionP->X_op_symbol = NULL;
	  expressionP->X_add_number += diff;
	}
      break;
    default:
      break;
    }
}

/* Expression parser. */

/*
 * We allow an empty expression, and just assume (absolute,0) silently.
 * Unary operators and parenthetical expressions are treated as operands.
 * As usual, Q==quantity==operand, O==operator, X==expression mnemonics.
 *
 * We used to do a aho/ullman shift-reduce parser, but the logic got so
 * warped that I flushed it and wrote a recursive-descent parser instead.
 * Now things are stable, would anybody like to write a fast parser?
 * Most expressions are either register (which does not even reach here)
 * or 1 symbol. Then "symbol+constant" and "symbol-symbol" are common.
 * So I guess it doesn't really matter how inefficient more complex expressions
 * are parsed.
 *
 * After expr(RANK,resultP) input_line_pointer->operator of rank <= RANK.
 * Also, we have consumed any leading or trailing spaces (operand does that)
 * and done all intervening operators.
 *
 * This returns the segment of the result, which will be
 * absolute_section or the segment of a symbol.
 */

#undef __
#define __ O_illegal

static operatorT op_encoding[256] =
{				/* maps ASCII->operators */

  __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __,
  __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __,

  __, O_bit_or_not, __, __, __, O_modulus, O_bit_and, __,
  __, __, O_multiply, O_add, __, O_subtract, __, O_divide,
  __, __, __, __, __, __, __, __,
  __, __, __, __, O_lt, __, O_gt, __,
  __, __, __, __, __, __, __, __,
  __, __, __, __, __, __, __, __,
  __, __, __, __, __, __, __, __,
  __, __, __, __, __, __, O_bit_exclusive_or, __,
  __, __, __, __, __, __, __, __,
  __, __, __, __, __, __, __, __,
  __, __, __, __, __, __, __, __,
  __, __, __, __, O_bit_inclusive_or, __, __, __,

  __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __,
  __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __,
  __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __,
  __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __,
  __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __,
  __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __,
  __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __,
  __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __
};


/*
 *	Rank	Examples
 *	0	operand, (expression)
 *	1	||
 *	2	&&
 *	3	= <> < <= >= >
 *	4	+ -
 *	5	used for * / % in MRI mode
 *	6	& ^ ! |
 *	7	* / % << >>
 *	8	unary - unary ~
 */
static operator_rankT op_rank[] =
{
  0,	/* O_illegal */
  0,	/* O_absent */
  0,	/* O_constant */
  0,	/* O_symbol */
  0,	/* O_symbol_rva */
  0,	/* O_register */
  0,	/* O_bit */
  8,	/* O_uminus */
  8,	/* O_bit_not */
  8,	/* O_logical_not */
  7,	/* O_multiply */
  7,	/* O_divide */
  7,	/* O_modulus */
  7,	/* O_left_shift */
  7,	/* O_right_shift */
  6,	/* O_bit_inclusive_or */
  6,	/* O_bit_or_not */
  6,	/* O_bit_exclusive_or */
  6,	/* O_bit_and */
  4,	/* O_add */
  4,	/* O_subtract */
  3,	/* O_eq */
  3,	/* O_ne */
  3,	/* O_lt */
  3,	/* O_le */
  3,	/* O_ge */
  3,	/* O_gt */
  2,	/* O_logical_and */
  1	/* O_logical_or */
};

/* Initialize the expression parser.  */

void
expr_begin ()
{
  /* In MRI mode for the m68k, multiplication and division have lower
     precedence than the bit wise operators.  */
  if (flag_m68k_mri)
    {
      op_rank[O_multiply] = 5;
      op_rank[O_divide] = 5;
      op_rank[O_modulus] = 5;
      op_encoding['"'] = O_bit_not;
    }

  /* Verify that X_op field is wide enough.  */
  {
    expressionS e;
    e.X_op = O_max;
    assert (e.X_op == O_max);
  }
}

/* Return the encoding for the operator at INPUT_LINE_POINTER.
   Advance INPUT_LINE_POINTER to the last character in the operator
   (i.e., don't change it for a single character operator).  */

static inline operatorT
operator ()
{
  int c;
  operatorT ret;

  c = *input_line_pointer;

  switch (c)
    {
    default:
      return op_encoding[c];

    case '<':
      switch (input_line_pointer[1])
	{
	default:
	  return op_encoding[c];
	case '<':
	  ret = O_left_shift;
	  break;
	case '>':
	  ret = O_ne;
	  break;
	case '=':
	  ret = O_le;
	  break;
	}
      ++input_line_pointer;
      return ret;

    case '=':
      if (input_line_pointer[1] != '=')
	return op_encoding[c];

      ++input_line_pointer;
      return O_eq;

    case '>':
      switch (input_line_pointer[1])
	{
	default:
	  return op_encoding[c];
	case '>':
	  ret = O_right_shift;
	  break;
	case '=':
	  ret = O_ge;
	  break;
	}
      ++input_line_pointer;
      return ret;

    case '!':
      /* We accept !! as equivalent to ^ for MRI compatibility.  */
      if (input_line_pointer[1] != '!')
	{
	  if (flag_m68k_mri)
	    return O_bit_inclusive_or;
	  return op_encoding[c];
	}
      ++input_line_pointer;
      return O_bit_exclusive_or;

    case '|':
      if (input_line_pointer[1] != '|')
	return op_encoding[c];

      ++input_line_pointer;
      return O_logical_or;

    case '&':
      if (input_line_pointer[1] != '&')
	return op_encoding[c];

      ++input_line_pointer;
      return O_logical_and;
    }

  /*NOTREACHED*/
}

/* Parse an expression.  */

segT
expr (rank, resultP)
     operator_rankT rank;	/* Larger # is higher rank. */
     expressionS *resultP;	/* Deliver result here. */
{
  segT retval;
  expressionS right;
  operatorT op_left;
  operatorT op_right;

  know (rank >= 0);

  retval = operand (resultP);

  know (*input_line_pointer != ' ');	/* Operand() gobbles spaces. */

  op_left = operator ();
  while (op_left != O_illegal && op_rank[(int) op_left] > rank)
    {
      segT rightseg;

      input_line_pointer++;	/*->after 1st character of operator. */

      rightseg = expr (op_rank[(int) op_left], &right);
      if (right.X_op == O_absent)
	{
	  as_warn ("missing operand; zero assumed");
	  right.X_op = O_constant;
	  right.X_add_number = 0;
	  right.X_add_symbol = NULL;
	  right.X_op_symbol = NULL;
	}

      know (*input_line_pointer != ' ');

      if (retval == undefined_section)
	{
	  if (SEG_NORMAL (rightseg))
	    retval = rightseg;
	}
      else if (! SEG_NORMAL (retval))
	retval = rightseg;
      else if (SEG_NORMAL (rightseg)
	       && retval != rightseg
#ifdef DIFF_EXPR_OK
	       && op_left != O_subtract
#endif
	       )
	as_bad ("operation combines symbols in different segments");

      op_right = operator ();

      know (op_right == O_illegal || op_rank[(int) op_right] <= op_rank[(int) op_left]);
      know ((int) op_left >= (int) O_multiply
	    && (int) op_left <= (int) O_logical_or);

      /* input_line_pointer->after right-hand quantity. */
      /* left-hand quantity in resultP */
      /* right-hand quantity in right. */
      /* operator in op_left. */

      if (resultP->X_op == O_big)
	{
	  as_warn ("left operand is a %s; integer 0 assumed",
		   resultP->X_add_number > 0 ? "bignum" : "float");
	  resultP->X_op = O_constant;
	  resultP->X_add_number = 0;
	  resultP->X_add_symbol = NULL;
	  resultP->X_op_symbol = NULL;
	}
      if (right.X_op == O_big)
	{
	  as_warn ("right operand is a %s; integer 0 assumed",
		   right.X_add_number > 0 ? "bignum" : "float");
	  right.X_op = O_constant;
	  right.X_add_number = 0;
	  right.X_add_symbol = NULL;
	  right.X_op_symbol = NULL;
	}

      /* Optimize common cases.  */
      if (op_left == O_add && right.X_op == O_constant)
	{
	  /* X + constant.  */
	  resultP->X_add_number += right.X_add_number;
	}
      /* This case comes up in PIC code.  */
      else if (op_left == O_subtract
	       && right.X_op == O_symbol
	       && resultP->X_op == O_symbol
	       && (right.X_add_symbol->sy_frag
		   == resultP->X_add_symbol->sy_frag)
	       && SEG_NORMAL (S_GET_SEGMENT (right.X_add_symbol)))

	{
	  resultP->X_add_number -= right.X_add_number;
	  resultP->X_add_number += (S_GET_VALUE (resultP->X_add_symbol)
				    - S_GET_VALUE (right.X_add_symbol));
	  resultP->X_op = O_constant;
	  resultP->X_add_symbol = 0;
	}
      else if (op_left == O_subtract && right.X_op == O_constant)
	{
	  /* X - constant.  */
	  resultP->X_add_number -= right.X_add_number;
	}
      else if (op_left == O_add && resultP->X_op == O_constant)
	{
	  /* Constant + X.  */
	  resultP->X_op = right.X_op;
	  resultP->X_add_symbol = right.X_add_symbol;
	  resultP->X_op_symbol = right.X_op_symbol;
	  resultP->X_add_number += right.X_add_number;
	  retval = rightseg;
	}
      else if (resultP->X_op == O_constant && right.X_op == O_constant)
	{
	  /* Constant OP constant.  */
	  offsetT v = right.X_add_number;
	  if (v == 0 && (op_left == O_divide || op_left == O_modulus))
	    {
	      as_warn ("division by zero");
	      v = 1;
	    }
	  switch (op_left)
	    {
	    default:			abort ();
	    case O_multiply:		resultP->X_add_number *= v; break;
	    case O_divide:		resultP->X_add_number /= v; break;
	    case O_modulus:		resultP->X_add_number %= v; break;
	    case O_left_shift:		resultP->X_add_number <<= v; break;
	    case O_right_shift:
	      /* We always use unsigned shifts, to avoid relying on
                 characteristics of the compiler used to compile gas.  */
	      resultP->X_add_number =
		(offsetT) ((valueT) resultP->X_add_number >> (valueT) v);
	      break;
	    case O_bit_inclusive_or:	resultP->X_add_number |= v; break;
	    case O_bit_or_not:		resultP->X_add_number |= ~v; break;
	    case O_bit_exclusive_or:	resultP->X_add_number ^= v; break;
	    case O_bit_and:		resultP->X_add_number &= v; break;
	    case O_add:			resultP->X_add_number += v; break;
	    case O_subtract:		resultP->X_add_number -= v; break;
	    case O_eq:
	      resultP->X_add_number =
		resultP->X_add_number == v ? ~ (offsetT) 0 : 0;
	      break;
	    case O_ne:
	      resultP->X_add_number =
		resultP->X_add_number != v ? ~ (offsetT) 0 : 0;
	      break;
	    case O_lt:
	      resultP->X_add_number =
		resultP->X_add_number <  v ? ~ (offsetT) 0 : 0;
	      break;
	    case O_le:
	      resultP->X_add_number =
		resultP->X_add_number <= v ? ~ (offsetT) 0 : 0;
	      break;
	    case O_ge:
	      resultP->X_add_number =
		resultP->X_add_number >= v ? ~ (offsetT) 0 : 0;
	      break;
	    case O_gt:
	      resultP->X_add_number =
		resultP->X_add_number >  v ? ~ (offsetT) 0 : 0;
	      break;
	    case O_logical_and:
	      resultP->X_add_number = resultP->X_add_number && v;
	      break;
	    case O_logical_or:
	      resultP->X_add_number = resultP->X_add_number || v;
	      break;
	    }
	}
      else if (resultP->X_op == O_symbol
	       && right.X_op == O_symbol
	       && (op_left == O_add
		   || op_left == O_subtract
		   || (resultP->X_add_number == 0
		       && right.X_add_number == 0)))
	{
	  /* Symbol OP symbol.  */
	  resultP->X_op = op_left;
	  resultP->X_op_symbol = right.X_add_symbol;
	  if (op_left == O_add)
	    resultP->X_add_number += right.X_add_number;
	  else if (op_left == O_subtract)
	    resultP->X_add_number -= right.X_add_number;
	}
      else
	{
	  /* The general case.  */
	  resultP->X_add_symbol = make_expr_symbol (resultP);
	  resultP->X_op_symbol = make_expr_symbol (&right);
	  resultP->X_op = op_left;
	  resultP->X_add_number = 0;
	  resultP->X_unsigned = 1;
	}

      op_left = op_right;
    }				/* While next operator is >= this rank. */

  /* The PA port needs this information.  */
  if (resultP->X_add_symbol)
    resultP->X_add_symbol->sy_used = 1;

  return resultP->X_op == O_constant ? absolute_section : retval;
}

/*
 *			get_symbol_end()
 *
 * This lives here because it belongs equally in expr.c & read.c.
 * Expr.c is just a branch office read.c anyway, and putting it
 * here lessens the crowd at read.c.
 *
 * Assume input_line_pointer is at start of symbol name.
 * Advance input_line_pointer past symbol name.
 * Turn that character into a '\0', returning its former value.
 * This allows a string compare (RMS wants symbol names to be strings)
 * of the symbol name.
 * There will always be a char following symbol name, because all good
 * lines end in end-of-line.
 */
char
get_symbol_end ()
{
  char c;

  /* We accept \001 in a name in case this is being called with a
     constructed string.  */
  if (is_name_beginner (c = *input_line_pointer++) || c == '\001')
    while (is_part_of_name (c = *input_line_pointer++)
	   || c == '\001')
      ;
  *--input_line_pointer = 0;
  return (c);
}


unsigned int
get_single_number ()
{
  expressionS exp;
  operand (&exp);
  return exp.X_add_number;

}

/* end of expr.c */