aboutsummaryrefslogtreecommitdiff
path: root/gdb/values.c
blob: 14ecccbd38454a59389212335a1ee357557fc2de (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
/* Low level packing and unpacking of values for GDB, the GNU Debugger.
   Copyright 1986, 1987, 1989, 1991 Free Software Foundation, Inc.

This file is part of GDB.

This program 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 of the License, or
(at your option) any later version.

This program 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 this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  */

#include "defs.h"
#include <string.h>
#include "symtab.h"
#include "gdbtypes.h"
#include "value.h"
#include "gdbcore.h"
#include "frame.h"
#include "command.h"
#include "gdbcmd.h"
#include "target.h"
#include "demangle.h"

/* Local function prototypes. */

static value
value_headof PARAMS ((value, struct type *, struct type *));

static void
show_values PARAMS ((char *, int));

static void
show_convenience PARAMS ((char *, int));

/* The value-history records all the values printed
   by print commands during this session.  Each chunk
   records 60 consecutive values.  The first chunk on
   the chain records the most recent values.
   The total number of values is in value_history_count.  */

#define VALUE_HISTORY_CHUNK 60

struct value_history_chunk
{
  struct value_history_chunk *next;
  value values[VALUE_HISTORY_CHUNK];
};

/* Chain of chunks now in use.  */

static struct value_history_chunk *value_history_chain;

static int value_history_count;	/* Abs number of last entry stored */

/* List of all value objects currently allocated
   (except for those released by calls to release_value)
   This is so they can be freed after each command.  */

static value all_values;

/* Allocate a  value  that has the correct length for type TYPE.  */

value
allocate_value (type)
     struct type *type;
{
  register value val;

  check_stub_type (type);

  val = (value) xmalloc (sizeof (struct value) + TYPE_LENGTH (type));
  VALUE_NEXT (val) = all_values;
  all_values = val;
  VALUE_TYPE (val) = type;
  VALUE_LVAL (val) = not_lval;
  VALUE_ADDRESS (val) = 0;
  VALUE_FRAME (val) = 0;
  VALUE_OFFSET (val) = 0;
  VALUE_BITPOS (val) = 0;
  VALUE_BITSIZE (val) = 0;
  VALUE_REPEATED (val) = 0;
  VALUE_REPETITIONS (val) = 0;
  VALUE_REGNO (val) = -1;
  VALUE_LAZY (val) = 0;
  VALUE_OPTIMIZED_OUT (val) = 0;
  return val;
}

/* Allocate a  value  that has the correct length
   for COUNT repetitions type TYPE.  */

value
allocate_repeat_value (type, count)
     struct type *type;
     int count;
{
  register value val;

  val = (value) xmalloc (sizeof (struct value) + TYPE_LENGTH (type) * count);
  VALUE_NEXT (val) = all_values;
  all_values = val;
  VALUE_TYPE (val) = type;
  VALUE_LVAL (val) = not_lval;
  VALUE_ADDRESS (val) = 0;
  VALUE_FRAME (val) = 0;
  VALUE_OFFSET (val) = 0;
  VALUE_BITPOS (val) = 0;
  VALUE_BITSIZE (val) = 0;
  VALUE_REPEATED (val) = 1;
  VALUE_REPETITIONS (val) = count;
  VALUE_REGNO (val) = -1;
  VALUE_LAZY (val) = 0;
  VALUE_OPTIMIZED_OUT (val) = 0;
  return val;
}

/* Return a mark in the value chain.  All values allocated after the
   mark is obtained (except for those released) are subject to being freed
   if a subsequent value_free_to_mark is passed the mark.  */
value
value_mark ()
{
  return all_values;
}

/* Free all values allocated since MARK was obtained by value_mark
   (except for those released).  */
void
value_free_to_mark (mark)
     value mark;
{
  value val, next;

  for (val = all_values; val && val != mark; val = next)
    {
      next = VALUE_NEXT (val);
      value_free (val);
    }
  all_values = val;
}

/* Free all the values that have been allocated (except for those released).
   Called after each command, successful or not.  */

void
free_all_values ()
{
  register value val, next;

  for (val = all_values; val; val = next)
    {
      next = VALUE_NEXT (val);
      value_free (val);
    }

  all_values = 0;
}

/* Remove VAL from the chain all_values
   so it will not be freed automatically.  */

void
release_value (val)
     register value val;
{
  register value v;

  if (all_values == val)
    {
      all_values = val->next;
      return;
    }

  for (v = all_values; v; v = v->next)
    {
      if (v->next == val)
	{
	  v->next = val->next;
	  break;
	}
    }
}

/* Return a copy of the value ARG.
   It contains the same contents, for same memory address,
   but it's a different block of storage.  */

value
value_copy (arg)
     value arg;
{
  register value val;
  register struct type *type = VALUE_TYPE (arg);
  if (VALUE_REPEATED (arg))
    val = allocate_repeat_value (type, VALUE_REPETITIONS (arg));
  else
    val = allocate_value (type);
  VALUE_LVAL (val) = VALUE_LVAL (arg);
  VALUE_ADDRESS (val) = VALUE_ADDRESS (arg);
  VALUE_OFFSET (val) = VALUE_OFFSET (arg);
  VALUE_BITPOS (val) = VALUE_BITPOS (arg);
  VALUE_BITSIZE (val) = VALUE_BITSIZE (arg);
  VALUE_REGNO (val) = VALUE_REGNO (arg);
  VALUE_LAZY (val) = VALUE_LAZY (arg);
  if (!VALUE_LAZY (val))
    {
      memcpy (VALUE_CONTENTS_RAW (val), VALUE_CONTENTS_RAW (arg),
	      TYPE_LENGTH (VALUE_TYPE (arg))
	      * (VALUE_REPEATED (arg) ? VALUE_REPETITIONS (arg) : 1));
    }
  return val;
}

/* Access to the value history.  */

/* Record a new value in the value history.
   Returns the absolute history index of the entry.
   Result of -1 indicates the value was not saved; otherwise it is the
   value history index of this new item.  */

int
record_latest_value (val)
     value val;
{
  int i;

  /* Check error now if about to store an invalid float.  We return -1
     to the caller, but allow them to continue, e.g. to print it as "Nan". */
  if (TYPE_CODE (VALUE_TYPE (val)) == TYPE_CODE_FLT)
    {
      unpack_double (VALUE_TYPE (val), VALUE_CONTENTS (val), &i);
      if (i) return -1;		/* Indicate value not saved in history */
    }

  /* Here we treat value_history_count as origin-zero
     and applying to the value being stored now.  */

  i = value_history_count % VALUE_HISTORY_CHUNK;
  if (i == 0)
    {
      register struct value_history_chunk *new
	= (struct value_history_chunk *)
	  xmalloc (sizeof (struct value_history_chunk));
      memset (new->values, 0, sizeof new->values);
      new->next = value_history_chain;
      value_history_chain = new;
    }

  value_history_chain->values[i] = val;
  release_value (val);

  /* Now we regard value_history_count as origin-one
     and applying to the value just stored.  */

  return ++value_history_count;
}

/* Return a copy of the value in the history with sequence number NUM.  */

value
access_value_history (num)
     int num;
{
  register struct value_history_chunk *chunk;
  register int i;
  register int absnum = num;

  if (absnum <= 0)
    absnum += value_history_count;

  if (absnum <= 0)
    {
      if (num == 0)
	error ("The history is empty.");
      else if (num == 1)
	error ("There is only one value in the history.");
      else
	error ("History does not go back to $$%d.", -num);
    }
  if (absnum > value_history_count)
    error ("History has not yet reached $%d.", absnum);

  absnum--;

  /* Now absnum is always absolute and origin zero.  */

  chunk = value_history_chain;
  for (i = (value_history_count - 1) / VALUE_HISTORY_CHUNK - absnum / VALUE_HISTORY_CHUNK;
       i > 0; i--)
    chunk = chunk->next;

  return value_copy (chunk->values[absnum % VALUE_HISTORY_CHUNK]);
}

/* Clear the value history entirely.
   Must be done when new symbol tables are loaded,
   because the type pointers become invalid.  */

void
clear_value_history ()
{
  register struct value_history_chunk *next;
  register int i;
  register value val;

  while (value_history_chain)
    {
      for (i = 0; i < VALUE_HISTORY_CHUNK; i++)
	if (val = value_history_chain->values[i])
	  free ((PTR)val);
      next = value_history_chain->next;
      free ((PTR)value_history_chain);
      value_history_chain = next;
    }
  value_history_count = 0;
}

static void
show_values (num_exp, from_tty)
     char *num_exp;
     int from_tty;
{
  register int i;
  register value val;
  static int num = 1;

  if (num_exp)
    {
      if (num_exp[0] == '+' && num_exp[1] == '\0')
	/* "info history +" should print from the stored position.  */
	;
      else
	/* "info history <exp>" should print around value number <exp>.  */
	num = parse_and_eval_address (num_exp) - 5;
    }
  else
    {
      /* "info history" means print the last 10 values.  */
      num = value_history_count - 9;
    }

  if (num <= 0)
    num = 1;

  for (i = num; i < num + 10 && i <= value_history_count; i++)
    {
      val = access_value_history (i);
      printf_filtered ("$%d = ", i);
      value_print (val, stdout, 0, Val_pretty_default);
      printf_filtered ("\n");
    }

  /* The next "info history +" should start after what we just printed.  */
  num += 10;

  /* Hitting just return after this command should do the same thing as
     "info history +".  If num_exp is null, this is unnecessary, since
     "info history +" is not useful after "info history".  */
  if (from_tty && num_exp)
    {
      num_exp[0] = '+';
      num_exp[1] = '\0';
    }
}

/* Internal variables.  These are variables within the debugger
   that hold values assigned by debugger commands.
   The user refers to them with a '$' prefix
   that does not appear in the variable names stored internally.  */

static struct internalvar *internalvars;

/* Look up an internal variable with name NAME.  NAME should not
   normally include a dollar sign.

   If the specified internal variable does not exist,
   one is created, with a void value.  */

struct internalvar *
lookup_internalvar (name)
     char *name;
{
  register struct internalvar *var;

  for (var = internalvars; var; var = var->next)
    if (!strcmp (var->name, name))
      return var;

  var = (struct internalvar *) xmalloc (sizeof (struct internalvar));
  var->name = concat (name, NULL);
  var->value = allocate_value (builtin_type_void);
  release_value (var->value);
  var->next = internalvars;
  internalvars = var;
  return var;
}

value
value_of_internalvar (var)
     struct internalvar *var;
{
  register value val;

#ifdef IS_TRAPPED_INTERNALVAR
  if (IS_TRAPPED_INTERNALVAR (var->name))
    return VALUE_OF_TRAPPED_INTERNALVAR (var);
#endif 

  val = value_copy (var->value);
  if (VALUE_LAZY (val))
    value_fetch_lazy (val);
  VALUE_LVAL (val) = lval_internalvar;
  VALUE_INTERNALVAR (val) = var;
  return val;
}

void
set_internalvar_component (var, offset, bitpos, bitsize, newval)
     struct internalvar *var;
     int offset, bitpos, bitsize;
     value newval;
{
  register char *addr = VALUE_CONTENTS (var->value) + offset;

#ifdef IS_TRAPPED_INTERNALVAR
  if (IS_TRAPPED_INTERNALVAR (var->name))
    SET_TRAPPED_INTERNALVAR (var, newval, bitpos, bitsize, offset);
#endif

  if (bitsize)
    modify_field (addr, (int) value_as_long (newval),
		  bitpos, bitsize);
  else
    memcpy (addr, VALUE_CONTENTS (newval), TYPE_LENGTH (VALUE_TYPE (newval)));
}

void
set_internalvar (var, val)
     struct internalvar *var;
     value val;
{
#ifdef IS_TRAPPED_INTERNALVAR
  if (IS_TRAPPED_INTERNALVAR (var->name))
    SET_TRAPPED_INTERNALVAR (var, val, 0, 0, 0);
#endif

  free ((PTR)var->value);
  var->value = value_copy (val);
  /* Force the value to be fetched from the target now, to avoid problems
     later when this internalvar is referenced and the target is gone or
     has changed.  */
  if (VALUE_LAZY (var->value))
    value_fetch_lazy (var->value);
  release_value (var->value);
}

char *
internalvar_name (var)
     struct internalvar *var;
{
  return var->name;
}

/* Free all internalvars.  Done when new symtabs are loaded,
   because that makes the values invalid.  */

void
clear_internalvars ()
{
  register struct internalvar *var;

  while (internalvars)
    {
      var = internalvars;
      internalvars = var->next;
      free ((PTR)var->name);
      free ((PTR)var->value);
      free ((PTR)var);
    }
}

static void
show_convenience (ignore, from_tty)
     char *ignore;
     int from_tty;
{
  register struct internalvar *var;
  int varseen = 0;

  for (var = internalvars; var; var = var->next)
    {
#ifdef IS_TRAPPED_INTERNALVAR
      if (IS_TRAPPED_INTERNALVAR (var->name))
	continue;
#endif
      if (!varseen)
	{
	  varseen = 1;
	}
      printf_filtered ("$%s = ", var->name);
      value_print (var->value, stdout, 0, Val_pretty_default);
      printf_filtered ("\n");
    }
  if (!varseen)
    printf ("No debugger convenience variables now defined.\n\
Convenience variables have names starting with \"$\";\n\
use \"set\" as in \"set $foo = 5\" to define them.\n");
}

/* Extract a value as a C number (either long or double).
   Knows how to convert fixed values to double, or
   floating values to long.
   Does not deallocate the value.  */

LONGEST
value_as_long (val)
     register value val;
{
  /* This coerces arrays and functions, which is necessary (e.g.
     in disassemble_command).  It also dereferences references, which
     I suspect is the most logical thing to do.  */
  if (TYPE_CODE (VALUE_TYPE (val)) != TYPE_CODE_ENUM)
    COERCE_ARRAY (val);
  return unpack_long (VALUE_TYPE (val), VALUE_CONTENTS (val));
}

double
value_as_double (val)
     register value val;
{
  double foo;
  int inv;
  
  foo = unpack_double (VALUE_TYPE (val), VALUE_CONTENTS (val), &inv);
  if (inv)
    error ("Invalid floating value found in program.");
  return foo;
}
/* Extract a value as a C pointer.
   Does not deallocate the value.  */
CORE_ADDR
value_as_pointer (val)
     value val;
{
  /* Assume a CORE_ADDR can fit in a LONGEST (for now).  Not sure
     whether we want this to be true eventually.  */
  return ADDR_BITS_REMOVE(value_as_long (val));
}

/* Unpack raw data (copied from debugee, target byte order) at VALADDR
   as a long, or as a double, assuming the raw data is described
   by type TYPE.  Knows how to convert different sizes of values
   and can convert between fixed and floating point.  We don't assume
   any alignment for the raw data.  Return value is in host byte order.

   If you want functions and arrays to be coerced to pointers, and
   references to be dereferenced, call value_as_long() instead.

   C++: It is assumed that the front-end has taken care of
   all matters concerning pointers to members.  A pointer
   to member which reaches here is considered to be equivalent
   to an INT (or some size).  After all, it is only an offset.  */

/* FIXME:  This should be rewritten as a switch statement for speed and
   ease of comprehension.  */

LONGEST
unpack_long (type, valaddr)
     struct type *type;
     char *valaddr;
{
  register enum type_code code = TYPE_CODE (type);
  register int len = TYPE_LENGTH (type);
  register int nosign = TYPE_UNSIGNED (type);

  if (code == TYPE_CODE_ENUM || code == TYPE_CODE_BOOL)
    code = TYPE_CODE_INT;
  if (code == TYPE_CODE_FLT)
    {
      if (len == sizeof (float))
	{
	  float retval;
	  memcpy (&retval, valaddr, sizeof (retval));
	  SWAP_TARGET_AND_HOST (&retval, sizeof (retval));
	  return retval;
	}

      if (len == sizeof (double))
	{
	  double retval;
	  memcpy (&retval, valaddr, sizeof (retval));
	  SWAP_TARGET_AND_HOST (&retval, sizeof (retval));
	  return retval;
	}
      else
	{
	  error ("Unexpected type of floating point number.");
	}
    }
  else if (code == TYPE_CODE_INT && nosign)
    {
      if (len == sizeof (char))
	{
	  unsigned char retval = * (unsigned char *) valaddr;
	  /* SWAP_TARGET_AND_HOST (&retval, sizeof (unsigned char)); */
	  return retval;
	}

      if (len == sizeof (short))
	{
	  unsigned short retval;
	  memcpy (&retval, valaddr, sizeof (retval));
	  SWAP_TARGET_AND_HOST (&retval, sizeof (retval));
	  return retval;
	}

      if (len == sizeof (int))
	{
	  unsigned int retval;
	  memcpy (&retval, valaddr, sizeof (retval));
	  SWAP_TARGET_AND_HOST (&retval, sizeof (retval));
	  return retval;
	}

      if (len == sizeof (long))
	{
	  unsigned long retval;
	  memcpy (&retval, valaddr, sizeof (retval));
	  SWAP_TARGET_AND_HOST (&retval, sizeof (retval));
	  return retval;
	}
#ifdef LONG_LONG
      if (len == sizeof (long long))
	{
	  unsigned long long retval;
	  memcpy (&retval, valaddr, sizeof (retval));
	  SWAP_TARGET_AND_HOST (&retval, sizeof (retval));
	  return retval;
	}
#endif
      else
	{
	  error ("That operation is not possible on an integer of that size.");
	}
    }
  else if (code == TYPE_CODE_INT)
    {
      if (len == sizeof (char))
	{
	  SIGNED char retval;	/* plain chars might be unsigned on host */
	  memcpy (&retval, valaddr, sizeof (retval));
	  SWAP_TARGET_AND_HOST (&retval, sizeof (retval));
	  return retval;
	}

      if (len == sizeof (short))
	{
	  short retval;
	  memcpy (&retval, valaddr, sizeof (retval));
	  SWAP_TARGET_AND_HOST (&retval, sizeof (retval));
	  return retval;
	}

      if (len == sizeof (int))
	{
	  int retval;
	  memcpy (&retval, valaddr, sizeof (retval));
	  SWAP_TARGET_AND_HOST (&retval, sizeof (retval));
	  return retval;
	}

      if (len == sizeof (long))
	{
	  long retval;
	  memcpy (&retval, valaddr, sizeof (retval));
	  SWAP_TARGET_AND_HOST (&retval, sizeof (retval));
	  return retval;
	}

#ifdef LONG_LONG
      if (len == sizeof (long long))
	{
	  long long retval;
	  memcpy (&retval, valaddr, sizeof (retval));
	  SWAP_TARGET_AND_HOST (&retval, sizeof (retval));
	  return retval;
	}
#endif
      else
	{
	  error ("That operation is not possible on an integer of that size.");
	}
    }
  /* Assume a CORE_ADDR can fit in a LONGEST (for now).  Not sure
     whether we want this to be true eventually.  */
  else if (code == TYPE_CODE_PTR
	   || code == TYPE_CODE_REF)
    {
      if (len == sizeof(long))
      {
	unsigned long retval;
	memcpy (&retval, valaddr, sizeof(retval));
	SWAP_TARGET_AND_HOST (&retval, sizeof(retval));
	return retval;
      }
      else if (len == sizeof(short))
      {
	unsigned short retval;
	memcpy (&retval, valaddr, len);
	SWAP_TARGET_AND_HOST (&retval, len);
	return retval;
      }
    }
  else if (code == TYPE_CODE_MEMBER)
    error ("not implemented: member types in unpack_long");
  else if (code == TYPE_CODE_CHAR)
    return *(unsigned char *)valaddr;

  error ("Value not integer or pointer.");
  return 0; 	/* For lint -- never reached */
}

/* Return a double value from the specified type and address.
   INVP points to an int which is set to 0 for valid value,
   1 for invalid value (bad float format).  In either case,
   the returned double is OK to use.  Argument is in target
   format, result is in host format.  */

double
unpack_double (type, valaddr, invp)
     struct type *type;
     char *valaddr;
     int *invp;
{
  register enum type_code code = TYPE_CODE (type);
  register int len = TYPE_LENGTH (type);
  register int nosign = TYPE_UNSIGNED (type);

  *invp = 0;			/* Assume valid.   */
  if (code == TYPE_CODE_FLT)
    {
      if (INVALID_FLOAT (valaddr, len))
	{
	  *invp = 1;
	  return 1.234567891011121314;
	}

      if (len == sizeof (float))
	{
	  float retval;
	  memcpy (&retval, valaddr, sizeof (retval));
	  SWAP_TARGET_AND_HOST (&retval, sizeof (retval));
	  return retval;
	}

      if (len == sizeof (double))
	{
	  double retval;
	  memcpy (&retval, valaddr, sizeof (retval));
	  SWAP_TARGET_AND_HOST (&retval, sizeof (retval));
	  return retval;
	}
      else
	{
	  error ("Unexpected type of floating point number.");
	  return 0; /* Placate lint.  */
	}
    }
  else if (nosign) {
   /* Unsigned -- be sure we compensate for signed LONGEST.  */
#ifdef LONG_LONG
   return (unsigned long long) unpack_long (type, valaddr);
#else
   return (unsigned long     ) unpack_long (type, valaddr);
#endif
  } else {
    /* Signed -- we are OK with unpack_long.  */
    return unpack_long (type, valaddr);
  }
}

/* Unpack raw data (copied from debugee, target byte order) at VALADDR
   as a CORE_ADDR, assuming the raw data is described by type TYPE.
   We don't assume any alignment for the raw data.  Return value is in
   host byte order.

   If you want functions and arrays to be coerced to pointers, and
   references to be dereferenced, call value_as_pointer() instead.

   C++: It is assumed that the front-end has taken care of
   all matters concerning pointers to members.  A pointer
   to member which reaches here is considered to be equivalent
   to an INT (or some size).  After all, it is only an offset.  */

CORE_ADDR
unpack_pointer (type, valaddr)
     struct type *type;
     char *valaddr;
{
#if 0
  /* The user should be able to use an int (e.g. 0x7892) in contexts
     where a pointer is expected.  So this doesn't do enough.  */
  register enum type_code code = TYPE_CODE (type);
  register int len = TYPE_LENGTH (type);

  if (code == TYPE_CODE_PTR
      || code == TYPE_CODE_REF)
    {
      if (len == sizeof (CORE_ADDR))
	{
	  CORE_ADDR retval;
	  memcpy (&retval, valaddr, sizeof (retval));
	  SWAP_TARGET_AND_HOST (&retval, sizeof (retval));
	  return retval;
	}
      error ("Unrecognized pointer size.");
    }
  else if (code == TYPE_CODE_MEMBER)
    error ("not implemented: member types in unpack_pointer");

  error ("Value is not a pointer.");
  return 0; 	/* For lint -- never reached */
#else
  /* Assume a CORE_ADDR can fit in a LONGEST (for now).  Not sure
     whether we want this to be true eventually.  */
  return unpack_long (type, valaddr);
#endif
}

/* Given a value ARG1 (offset by OFFSET bytes)
   of a struct or union type ARG_TYPE,
   extract and return the value of one of its fields.
   FIELDNO says which field.

   For C++, must also be able to return values from static fields */

value
value_primitive_field (arg1, offset, fieldno, arg_type)
     register value arg1;
     int offset;
     register int fieldno;
     register struct type *arg_type;
{
  register value v;
  register struct type *type;

  check_stub_type (arg_type);
  type = TYPE_FIELD_TYPE (arg_type, fieldno);

  /* Handle packed fields */

  offset += TYPE_FIELD_BITPOS (arg_type, fieldno) / 8;
  if (TYPE_FIELD_BITSIZE (arg_type, fieldno))
    {
      v = value_from_longest (type,
			   unpack_field_as_long (arg_type,
						 VALUE_CONTENTS (arg1),
						 fieldno));
      VALUE_BITPOS (v) = TYPE_FIELD_BITPOS (arg_type, fieldno) % 8;
      VALUE_BITSIZE (v) = TYPE_FIELD_BITSIZE (arg_type, fieldno);
    }
  else
    {
      v = allocate_value (type);
      if (VALUE_LAZY (arg1))
	VALUE_LAZY (v) = 1;
      else
	memcpy (VALUE_CONTENTS_RAW (v), VALUE_CONTENTS_RAW (arg1) + offset,
		TYPE_LENGTH (type));
    }
  VALUE_LVAL (v) = VALUE_LVAL (arg1);
  if (VALUE_LVAL (arg1) == lval_internalvar)
    VALUE_LVAL (v) = lval_internalvar_component;
  VALUE_ADDRESS (v) = VALUE_ADDRESS (arg1);
  VALUE_OFFSET (v) = offset + VALUE_OFFSET (arg1);
  return v;
}

/* Given a value ARG1 of a struct or union type,
   extract and return the value of one of its fields.
   FIELDNO says which field.

   For C++, must also be able to return values from static fields */

value
value_field (arg1, fieldno)
     register value arg1;
     register int fieldno;
{
  return value_primitive_field (arg1, 0, fieldno, VALUE_TYPE (arg1));
}

/* Return a non-virtual function as a value.
   F is the list of member functions which contains the desired method.
   J is an index into F which provides the desired method. */

value
value_fn_field (arg1p, f, j, type, offset)
     value *arg1p;
     struct fn_field *f;
     int j;
     struct type *type;
     int offset;
{
  register value v;
  register struct type *ftype = TYPE_FN_FIELD_TYPE (f, j);
  struct symbol *sym;

  sym = lookup_symbol (TYPE_FN_FIELD_PHYSNAME (f, j),
		       0, VAR_NAMESPACE, 0, NULL);
  if (! sym) error ("Internal error: could not find physical method named %s",
		    TYPE_FN_FIELD_PHYSNAME (f, j));
  
  v = allocate_value (ftype);
  VALUE_ADDRESS (v) = BLOCK_START (SYMBOL_BLOCK_VALUE (sym));
  VALUE_TYPE (v) = ftype;

  if (arg1p)
   {
    if (type != VALUE_TYPE (*arg1p))
      *arg1p = value_ind (value_cast (lookup_pointer_type (type),
				      value_addr (*arg1p)));

    /* Move the `this' pointer according to the offset. */
    VALUE_OFFSET (*arg1p) += offset;
    }

  return v;
}

/* Return a virtual function as a value.
   ARG1 is the object which provides the virtual function
   table pointer.  *ARG1P is side-effected in calling this function.
   F is the list of member functions which contains the desired virtual
   function.
   J is an index into F which provides the desired virtual function.

   TYPE is the type in which F is located.  */
value
value_virtual_fn_field (arg1p, f, j, type, offset)
     value *arg1p;
     struct fn_field *f;
     int j;
     struct type *type;
     int offset;
{
  value arg1 = *arg1p;
  /* First, get the virtual function table pointer.  That comes
     with a strange type, so cast it to type `pointer to long' (which
     should serve just fine as a function type).  Then, index into
     the table, and convert final value to appropriate function type.  */
  value entry, vfn, vtbl;
  value vi = value_from_longest (builtin_type_int, 
			      (LONGEST) TYPE_FN_FIELD_VOFFSET (f, j));
  struct type *fcontext = TYPE_FN_FIELD_FCONTEXT (f, j);
  struct type *context;
  if (fcontext == NULL)
   /* We don't have an fcontext (e.g. the program was compiled with
      g++ version 1).  Try to get the vtbl from the TYPE_VPTR_BASETYPE.
      This won't work right for multiple inheritance, but at least we
      should do as well as GDB 3.x did.  */
    fcontext = TYPE_VPTR_BASETYPE (type);
  context = lookup_pointer_type (fcontext);
  /* Now context is a pointer to the basetype containing the vtbl.  */
  if (TYPE_TARGET_TYPE (context) != VALUE_TYPE (arg1))
    arg1 = value_ind (value_cast (context, value_addr (arg1)));

  context = VALUE_TYPE (arg1);
  /* Now context is the basetype containing the vtbl.  */

  /* This type may have been defined before its virtual function table
     was.  If so, fill in the virtual function table entry for the
     type now.  */
  if (TYPE_VPTR_FIELDNO (context) < 0)
    fill_in_vptr_fieldno (context);

  /* The virtual function table is now an array of structures
     which have the form { int16 offset, delta; void *pfn; }.  */
  vtbl = value_ind (value_primitive_field (arg1, 0, 
					   TYPE_VPTR_FIELDNO (context),
					   TYPE_VPTR_BASETYPE (context)));

  /* Index into the virtual function table.  This is hard-coded because
     looking up a field is not cheap, and it may be important to save
     time, e.g. if the user has set a conditional breakpoint calling
     a virtual function.  */
  entry = value_subscript (vtbl, vi);

  /* Move the `this' pointer according to the virtual function table.  */
  VALUE_OFFSET (arg1) += value_as_long (value_field (entry, 0)) + offset;
  if (! VALUE_LAZY (arg1))
    {
      VALUE_LAZY (arg1) = 1;
      value_fetch_lazy (arg1);
    }

  vfn = value_field (entry, 2);
  /* Reinstantiate the function pointer with the correct type.  */
  VALUE_TYPE (vfn) = lookup_pointer_type (TYPE_FN_FIELD_TYPE (f, j));

  *arg1p = arg1;
  return vfn;
}

/* ARG is a pointer to an object we know to be at least
   a DTYPE.  BTYPE is the most derived basetype that has
   already been searched (and need not be searched again).
   After looking at the vtables between BTYPE and DTYPE,
   return the most derived type we find.  The caller must
   be satisfied when the return value == DTYPE.

   FIXME-tiemann: should work with dossier entries as well.  */

static value
value_headof (arg, btype, dtype)
     value arg;
     struct type *btype, *dtype;
{
  /* First collect the vtables we must look at for this object.  */
  /* FIXME-tiemann: right now, just look at top-most vtable.  */
  value vtbl, entry, best_entry = 0;
  int i, nelems;
  int offset, best_offset = 0;
  struct symbol *sym;
  CORE_ADDR pc_for_sym;
  char *demangled_name;
  struct minimal_symbol *msymbol;

  btype = TYPE_VPTR_BASETYPE (dtype);
  check_stub_type (btype);
  if (btype != dtype)
    vtbl = value_cast (lookup_pointer_type (btype), arg);
  else
    vtbl = arg;
  vtbl = value_ind (value_field (value_ind (vtbl), TYPE_VPTR_FIELDNO (btype)));

  /* Check that VTBL looks like it points to a virtual function table.  */
  msymbol = lookup_minimal_symbol_by_pc (VALUE_ADDRESS (vtbl));
  if (msymbol == NULL
      || !VTBL_PREFIX_P (demangled_name = msymbol -> name))
    {
      /* If we expected to find a vtable, but did not, let the user
	 know that we aren't happy, but don't throw an error.
	 FIXME: there has to be a better way to do this.  */
      struct type *error_type = (struct type *)xmalloc (sizeof (struct type));
      memcpy (error_type, VALUE_TYPE (arg), sizeof (struct type));
      TYPE_NAME (error_type) = savestring ("suspicious *", sizeof ("suspicious *"));
      VALUE_TYPE (arg) = error_type;
      return arg;
    }

  /* Now search through the virtual function table.  */
  entry = value_ind (vtbl);
  nelems = longest_to_int (value_as_long (value_field (entry, 2)));
  for (i = 1; i <= nelems; i++)
    {
      entry = value_subscript (vtbl, value_from_longest (builtin_type_int, 
						      (LONGEST) i));
      offset = longest_to_int (value_as_long (value_field (entry, 0)));
      /* If we use '<=' we can handle single inheritance
       * where all offsets are zero - just use the first entry found. */
      if (offset <= best_offset)
	{
	  best_offset = offset;
	  best_entry = entry;
	}
    }
  /* Move the pointer according to BEST_ENTRY's offset, and figure
     out what type we should return as the new pointer.  */
  if (best_entry == 0)
    {
      /* An alternative method (which should no longer be necessary).
       * But we leave it in for future use, when we will hopefully
       * have optimizes the vtable to use thunks instead of offsets. */
      /* Use the name of vtable itself to extract a base type. */
      demangled_name += 4;  /* Skip _vt$ prefix. */
    }
  else
    {
      pc_for_sym = value_as_pointer (value_field (best_entry, 2));
      sym = find_pc_function (pc_for_sym);
      demangled_name = cplus_demangle (SYMBOL_NAME (sym), DMGL_ANSI);
      *(strchr (demangled_name, ':')) = '\0';
    }
  sym = lookup_symbol (demangled_name, 0, VAR_NAMESPACE, 0, 0);
  if (sym == 0)
    error ("could not find type declaration for `%s'", SYMBOL_NAME (sym));
  if (best_entry)
    {
      free (demangled_name);
      arg = value_add (value_cast (builtin_type_int, arg),
		       value_field (best_entry, 0));
    }
  VALUE_TYPE (arg) = lookup_pointer_type (SYMBOL_TYPE (sym));
  return arg;
}

/* ARG is a pointer object of type TYPE.  If TYPE has virtual
   function tables, probe ARG's tables (including the vtables
   of its baseclasses) to figure out the most derived type that ARG
   could actually be a pointer to.  */

value
value_from_vtable_info (arg, type)
     value arg;
     struct type *type;
{
  /* Take care of preliminaries.  */
  if (TYPE_VPTR_FIELDNO (type) < 0)
    fill_in_vptr_fieldno (type);
  if (TYPE_VPTR_FIELDNO (type) < 0 || VALUE_REPEATED (arg))
    return 0;

  return value_headof (arg, 0, type);
}

/* Compute the offset of the baseclass which is
   the INDEXth baseclass of class TYPE, for a value ARG,
   wih extra offset of OFFSET.
   The result is the offste of the baseclass value relative
   to (the address of)(ARG) + OFFSET.

   -1 is returned on error. */

int
baseclass_offset (type, index, arg, offset)
     struct type *type;
     int index;
     value arg;
     int offset;
{
  struct type *basetype = TYPE_BASECLASS (type, index);

  if (BASETYPE_VIA_VIRTUAL (type, index))
    {
      /* Must hunt for the pointer to this virtual baseclass.  */
      register int i, len = TYPE_NFIELDS (type);
      register int n_baseclasses = TYPE_N_BASECLASSES (type);
      char *vbase_name, *type_name = type_name_no_tag (basetype);

      vbase_name = (char *)alloca (strlen (type_name) + 8);
      sprintf (vbase_name, "_vb%c%s", CPLUS_MARKER, type_name);
      /* First look for the virtual baseclass pointer
	 in the fields.  */
      for (i = n_baseclasses; i < len; i++)
	{
	  if (! strcmp (vbase_name, TYPE_FIELD_NAME (type, i)))
	    {
	      CORE_ADDR addr
		= unpack_pointer (TYPE_FIELD_TYPE (type, i),
				  VALUE_CONTENTS (arg) + VALUE_OFFSET (arg)
				  + offset
				  + (TYPE_FIELD_BITPOS (type, i) / 8));

	      if (VALUE_LVAL (arg) != lval_memory)
		  return -1;

	      return addr -
		  (LONGEST) (VALUE_ADDRESS (arg) + VALUE_OFFSET (arg) + offset);
	    }
	}
      /* Not in the fields, so try looking through the baseclasses.  */
      for (i = index+1; i < n_baseclasses; i++)
	{
	  int boffset =
	      baseclass_offset (type, i, arg, offset);
	  if (boffset)
	    return boffset;
	}
      /* Not found.  */
      return -1;
    }

  /* Baseclass is easily computed.  */
  return TYPE_BASECLASS_BITPOS (type, index) / 8;
}

/* Compute the address of the baseclass which is
   the INDEXth baseclass of class TYPE.  The TYPE base
   of the object is at VALADDR.

   If ERRP is non-NULL, set *ERRP to be the errno code of any error,
   or 0 if no error.  In that case the return value is not the address
   of the baseclasss, but the address which could not be read
   successfully.  */

/* FIXME Fix remaining uses of baseclass_addr to use baseclass_offset */

char *
baseclass_addr (type, index, valaddr, valuep, errp)
     struct type *type;
     int index;
     char *valaddr;
     value *valuep;
     int *errp;
{
  struct type *basetype = TYPE_BASECLASS (type, index);

  if (errp)
    *errp = 0;

  if (BASETYPE_VIA_VIRTUAL (type, index))
    {
      /* Must hunt for the pointer to this virtual baseclass.  */
      register int i, len = TYPE_NFIELDS (type);
      register int n_baseclasses = TYPE_N_BASECLASSES (type);
      char *vbase_name, *type_name = type_name_no_tag (basetype);

      vbase_name = (char *)alloca (strlen (type_name) + 8);
      sprintf (vbase_name, "_vb%c%s", CPLUS_MARKER, type_name);
      /* First look for the virtual baseclass pointer
	 in the fields.  */
      for (i = n_baseclasses; i < len; i++)
	{
	  if (! strcmp (vbase_name, TYPE_FIELD_NAME (type, i)))
	    {
	      value val = allocate_value (basetype);
	      CORE_ADDR addr;
	      int status;

	      addr
		= unpack_pointer (TYPE_FIELD_TYPE (type, i),
				  valaddr + (TYPE_FIELD_BITPOS (type, i) / 8));

	      status = target_read_memory (addr,
					   VALUE_CONTENTS_RAW (val),
					   TYPE_LENGTH (basetype));
	      VALUE_LVAL (val) = lval_memory;
	      VALUE_ADDRESS (val) = addr;

	      if (status != 0)
		{
		  if (valuep)
		    *valuep = NULL;
		  release_value (val);
		  value_free (val);
		  if (errp)
		    *errp = status;
		  return (char *)addr;
		}
	      else
		{
		  if (valuep)
		    *valuep = val;
		  return (char *) VALUE_CONTENTS (val);
		}
	    }
	}
      /* Not in the fields, so try looking through the baseclasses.  */
      for (i = index+1; i < n_baseclasses; i++)
	{
	  char *baddr;

	  baddr = baseclass_addr (type, i, valaddr, valuep, errp);
	  if (baddr)
	    return baddr;
	}
      /* Not found.  */
      if (valuep)
	*valuep = 0;
      return 0;
    }

  /* Baseclass is easily computed.  */
  if (valuep)
    *valuep = 0;
  return valaddr + TYPE_BASECLASS_BITPOS (type, index) / 8;
}

/* Unpack a field FIELDNO of the specified TYPE, from the anonymous object at
   VALADDR.

   Extracting bits depends on endianness of the machine.  Compute the
   number of least significant bits to discard.  For big endian machines,
   we compute the total number of bits in the anonymous object, subtract
   off the bit count from the MSB of the object to the MSB of the
   bitfield, then the size of the bitfield, which leaves the LSB discard
   count.  For little endian machines, the discard count is simply the
   number of bits from the LSB of the anonymous object to the LSB of the
   bitfield.

   If the field is signed, we also do sign extension. */

LONGEST
unpack_field_as_long (type, valaddr, fieldno)
     struct type *type;
     char *valaddr;
     int fieldno;
{
  unsigned LONGEST val;
  unsigned LONGEST valmask;
  int bitpos = TYPE_FIELD_BITPOS (type, fieldno);
  int bitsize = TYPE_FIELD_BITSIZE (type, fieldno);
  int lsbcount;

  memcpy (&val, valaddr + bitpos / 8, sizeof (val));
  SWAP_TARGET_AND_HOST (&val, sizeof (val));

  /* Extract bits.  See comment above. */

#if BITS_BIG_ENDIAN
  lsbcount = (sizeof val * 8 - bitpos % 8 - bitsize);
#else
  lsbcount = (bitpos % 8);
#endif
  val >>= lsbcount;

  /* If the field does not entirely fill a LONGEST, then zero the sign bits.
     If the field is signed, and is negative, then sign extend. */

  if ((bitsize > 0) && (bitsize < 8 * sizeof (val)))
    {
      valmask = (((unsigned LONGEST) 1) << bitsize) - 1;
      val &= valmask;
      if (!TYPE_UNSIGNED (TYPE_FIELD_TYPE (type, fieldno)))
	{
	  if (val & (valmask ^ (valmask >> 1)))
	    {
	      val |= ~valmask;
	    }
	}
    }
  return (val);
}

/* Modify the value of a bitfield.  ADDR points to a block of memory in
   target byte order; the bitfield starts in the byte pointed to.  FIELDVAL
   is the desired value of the field, in host byte order.  BITPOS and BITSIZE
   indicate which bits (in target bit order) comprise the bitfield.  */

void
modify_field (addr, fieldval, bitpos, bitsize)
     char *addr;
     int fieldval;
     int bitpos, bitsize;
{
  long oword;

  /* Reject values too big to fit in the field in question,
     otherwise adjoining fields may be corrupted.  */
  if (bitsize < (8 * sizeof (fieldval))
      && 0 != (fieldval & ~((1<<bitsize)-1)))
    error ("Value %d does not fit in %d bits.", fieldval, bitsize);
  
  memcpy (&oword, addr, sizeof oword);
  SWAP_TARGET_AND_HOST (&oword, sizeof oword);		/* To host format */

  /* Shifting for bit field depends on endianness of the target machine.  */
#if BITS_BIG_ENDIAN
  bitpos = sizeof (oword) * 8 - bitpos - bitsize;
#endif

  /* Mask out old value, while avoiding shifts >= longword size */
  if (bitsize < 8 * sizeof (oword))
    oword &= ~(((((unsigned long)1) << bitsize) - 1) << bitpos);
  else
    oword &= ~((-1) << bitpos);
  oword |= fieldval << bitpos;

  SWAP_TARGET_AND_HOST (&oword, sizeof oword);		/* To target format */
  memcpy (addr, &oword, sizeof oword);
}

/* Convert C numbers into newly allocated values */

value
value_from_longest (type, num)
     struct type *type;
     register LONGEST num;
{
  register value val = allocate_value (type);
  register enum type_code code = TYPE_CODE (type);
  register int len = TYPE_LENGTH (type);

  /* FIXME, we assume that pointers have the same form and byte order as
     integers, and that all pointers have the same form.  */
  if (code == TYPE_CODE_INT  || code == TYPE_CODE_ENUM || 
      code == TYPE_CODE_CHAR || code == TYPE_CODE_PTR ||
      code == TYPE_CODE_REF  || code == TYPE_CODE_BOOL)
    {
      if (len == sizeof (char))
	* (char *) VALUE_CONTENTS_RAW (val) = num;
      else if (len == sizeof (short))
	* (short *) VALUE_CONTENTS_RAW (val) = num;
      else if (len == sizeof (int))
	* (int *) VALUE_CONTENTS_RAW (val) = num;
      else if (len == sizeof (long))
	* (long *) VALUE_CONTENTS_RAW (val) = num;
#ifdef LONG_LONG
      else if (len == sizeof (long long))
	* (long long *) VALUE_CONTENTS_RAW (val) = num;
#endif
      else
	error ("Integer type encountered with unexpected data length.");
    }
  else
    error ("Unexpected type encountered for integer constant.");

  /* num was in host byte order.  So now put the value's contents
     into target byte order.  */
  SWAP_TARGET_AND_HOST (VALUE_CONTENTS_RAW (val), len);

  return val;
}

value
value_from_double (type, num)
     struct type *type;
     double num;
{
  register value val = allocate_value (type);
  register enum type_code code = TYPE_CODE (type);
  register int len = TYPE_LENGTH (type);

  if (code == TYPE_CODE_FLT)
    {
      if (len == sizeof (float))
	* (float *) VALUE_CONTENTS_RAW (val) = num;
      else if (len == sizeof (double))
	* (double *) VALUE_CONTENTS_RAW (val) = num;
      else
	error ("Floating type encountered with unexpected data length.");
    }
  else
    error ("Unexpected type encountered for floating constant.");

  /* num was in host byte order.  So now put the value's contents
     into target byte order.  */
  SWAP_TARGET_AND_HOST (VALUE_CONTENTS_RAW (val), len);

  return val;
}

/* Deal with the value that is "about to be returned".  */

/* Return the value that a function returning now
   would be returning to its caller, assuming its type is VALTYPE.
   RETBUF is where we look for what ought to be the contents
   of the registers (in raw form).  This is because it is often
   desirable to restore old values to those registers
   after saving the contents of interest, and then call
   this function using the saved values.
   struct_return is non-zero when the function in question is
   using the structure return conventions on the machine in question;
   0 when it is using the value returning conventions (this often
   means returning pointer to where structure is vs. returning value). */

value
value_being_returned (valtype, retbuf, struct_return)
     register struct type *valtype;
     char retbuf[REGISTER_BYTES];
     int struct_return;
     /*ARGSUSED*/
{
  register value val;
  CORE_ADDR addr;

#if defined (EXTRACT_STRUCT_VALUE_ADDRESS)
  /* If this is not defined, just use EXTRACT_RETURN_VALUE instead.  */
  if (struct_return) {
    addr = EXTRACT_STRUCT_VALUE_ADDRESS (retbuf);
    if (!addr)
      error ("Function return value unknown");
    return value_at (valtype, addr);
  }
#endif

  val = allocate_value (valtype);
  EXTRACT_RETURN_VALUE (valtype, retbuf, VALUE_CONTENTS_RAW (val));

  return val;
}

/* Should we use EXTRACT_STRUCT_VALUE_ADDRESS instead of
   EXTRACT_RETURN_VALUE?  GCC_P is true if compiled with gcc
   and TYPE is the type (which is known to be struct, union or array).

   On most machines, the struct convention is used unless we are
   using gcc and the type is of a special size.  */
#if !defined (USE_STRUCT_CONVENTION)
#define USE_STRUCT_CONVENTION(gcc_p, type)\
  (!((gcc_p) && (TYPE_LENGTH (value_type) == 1                \
		 || TYPE_LENGTH (value_type) == 2             \
	         || TYPE_LENGTH (value_type) == 4             \
		 || TYPE_LENGTH (value_type) == 8             \
		 )                                            \
     ))
#endif

/* Return true if the function specified is using the structure returning
   convention on this machine to return arguments, or 0 if it is using
   the value returning convention.  FUNCTION is the value representing
   the function, FUNCADDR is the address of the function, and VALUE_TYPE
   is the type returned by the function.  GCC_P is nonzero if compiled
   with GCC.  */

int
using_struct_return (function, funcaddr, value_type, gcc_p)
     value function;
     CORE_ADDR funcaddr;
     struct type *value_type;
     int gcc_p;
     /*ARGSUSED*/
{
  register enum type_code code = TYPE_CODE (value_type);

  if (code == TYPE_CODE_ERROR)
    error ("Function return type unknown.");

  if (code == TYPE_CODE_STRUCT ||
      code == TYPE_CODE_UNION ||
      code == TYPE_CODE_ARRAY)
    return USE_STRUCT_CONVENTION (gcc_p, value_type);

  return 0;
}

/* Store VAL so it will be returned if a function returns now.
   Does not verify that VAL's type matches what the current
   function wants to return.  */

void
set_return_value (val)
     value val;
{
  register enum type_code code = TYPE_CODE (VALUE_TYPE (val));
  double dbuf;
  LONGEST lbuf;

  if (code == TYPE_CODE_ERROR)
    error ("Function return type unknown.");

  if (   code == TYPE_CODE_STRUCT
      || code == TYPE_CODE_UNION)	/* FIXME, implement struct return.  */
    error ("GDB does not support specifying a struct or union return value.");

  /* FIXME, this is bogus.  We don't know what the return conventions
     are, or how values should be promoted.... */
  if (code == TYPE_CODE_FLT)
    {
      dbuf = value_as_double (val);

      STORE_RETURN_VALUE (VALUE_TYPE (val), (char *)&dbuf);
    }
  else
    {
      lbuf = value_as_long (val);
      STORE_RETURN_VALUE (VALUE_TYPE (val), (char *)&lbuf);
    }
}

void
_initialize_values ()
{
  add_cmd ("convenience", no_class, show_convenience,
	    "Debugger convenience (\"$foo\") variables.\n\
These variables are created when you assign them values;\n\
thus, \"print $foo=1\" gives \"$foo\" the value 1.  Values may be any type.\n\n\
A few convenience variables are given values automatically:\n\
\"$_\"holds the last address examined with \"x\" or \"info lines\",\n\
\"$__\" holds the contents of the last address examined with \"x\".",
	   &showlist);

  add_cmd ("values", no_class, show_values,
	   "Elements of value history around item number IDX (or last ten).",
	   &showlist);
}