summaryrefslogtreecommitdiff
path: root/gdb/m68k-tdep.c
blob: 082cb84ff80aa0e8142662f2e2f156c713592dbf (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
/* Target-dependent code for the Motorola 68000 series.

   Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1999, 2000, 2001,
   2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011
   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 3 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, see <http://www.gnu.org/licenses/>.  */

#include "defs.h"
#include "dwarf2-frame.h"
#include "frame.h"
#include "frame-base.h"
#include "frame-unwind.h"
#include "gdbtypes.h"
#include "symtab.h"
#include "gdbcore.h"
#include "value.h"
#include "gdb_string.h"
#include "gdb_assert.h"
#include "inferior.h"
#include "regcache.h"
#include "arch-utils.h"
#include "osabi.h"
#include "dis-asm.h"
#include "target-descriptions.h"

#include "m68k-tdep.h"


#define P_LINKL_FP	0x480e
#define P_LINKW_FP	0x4e56
#define P_PEA_FP	0x4856
#define P_MOVEAL_SP_FP	0x2c4f
#define P_ADDAW_SP	0xdefc
#define P_ADDAL_SP	0xdffc
#define P_SUBQW_SP	0x514f
#define P_SUBQL_SP	0x518f
#define P_LEA_SP_SP	0x4fef
#define P_LEA_PC_A5	0x4bfb0170
#define P_FMOVEMX_SP	0xf227
#define P_MOVEL_SP	0x2f00
#define P_MOVEML_SP	0x48e7

/* Offset from SP to first arg on stack at first instruction of a function.  */
#define SP_ARG0 (1 * 4)

#if !defined (BPT_VECTOR)
#define BPT_VECTOR 0xf
#endif

static const gdb_byte *
m68k_local_breakpoint_from_pc (struct gdbarch *gdbarch,
			       CORE_ADDR *pcptr, int *lenptr)
{
  static gdb_byte break_insn[] = {0x4e, (0x40 | BPT_VECTOR)};
  *lenptr = sizeof (break_insn);
  return break_insn;
}


/* Construct types for ISA-specific registers.  */
static struct type *
m68k_ps_type (struct gdbarch *gdbarch)
{
  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);

  if (!tdep->m68k_ps_type)
    {
      struct type *type;

      type = arch_flags_type (gdbarch, "builtin_type_m68k_ps", 4);
      append_flags_type_flag (type, 0, "C");
      append_flags_type_flag (type, 1, "V");
      append_flags_type_flag (type, 2, "Z");
      append_flags_type_flag (type, 3, "N");
      append_flags_type_flag (type, 4, "X");
      append_flags_type_flag (type, 8, "I0");
      append_flags_type_flag (type, 9, "I1");
      append_flags_type_flag (type, 10, "I2");
      append_flags_type_flag (type, 12, "M");
      append_flags_type_flag (type, 13, "S");
      append_flags_type_flag (type, 14, "T0");
      append_flags_type_flag (type, 15, "T1");

      tdep->m68k_ps_type = type;
    }

  return tdep->m68k_ps_type;
}

static struct type *
m68881_ext_type (struct gdbarch *gdbarch)
{
  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);

  if (!tdep->m68881_ext_type)
    tdep->m68881_ext_type
      = arch_float_type (gdbarch, -1, "builtin_type_m68881_ext",
			 floatformats_m68881_ext);

  return tdep->m68881_ext_type;
}

/* Return the GDB type object for the "standard" data type of data in
   register N.  This should be int for D0-D7, SR, FPCONTROL and
   FPSTATUS, long double for FP0-FP7, and void pointer for all others
   (A0-A7, PC, FPIADDR).  Note, for registers which contain
   addresses return pointer to void, not pointer to char, because we
   don't want to attempt to print the string after printing the
   address.  */

static struct type *
m68k_register_type (struct gdbarch *gdbarch, int regnum)
{
  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);

  if (tdep->fpregs_present)
    {
      if (regnum >= gdbarch_fp0_regnum (gdbarch)
	  && regnum <= gdbarch_fp0_regnum (gdbarch) + 7)
	{
	  if (tdep->flavour == m68k_coldfire_flavour)
	    return builtin_type (gdbarch)->builtin_double;
	  else
	    return m68881_ext_type (gdbarch);
	}

      if (regnum == M68K_FPI_REGNUM)
	return builtin_type (gdbarch)->builtin_func_ptr;

      if (regnum == M68K_FPC_REGNUM || regnum == M68K_FPS_REGNUM)
	return builtin_type (gdbarch)->builtin_int32;
    }
  else
    {
      if (regnum >= M68K_FP0_REGNUM && regnum <= M68K_FPI_REGNUM)
	return builtin_type (gdbarch)->builtin_int0;
    }

  if (regnum == gdbarch_pc_regnum (gdbarch))
    return builtin_type (gdbarch)->builtin_func_ptr;

  if (regnum >= M68K_A0_REGNUM && regnum <= M68K_A0_REGNUM + 7)
    return builtin_type (gdbarch)->builtin_data_ptr;

  if (regnum == M68K_PS_REGNUM)
    return m68k_ps_type (gdbarch);

  return builtin_type (gdbarch)->builtin_int32;
}

static const char *m68k_register_names[] = {
    "d0", "d1", "d2", "d3", "d4", "d5", "d6", "d7",
    "a0", "a1", "a2", "a3", "a4", "a5", "fp", "sp",
    "ps", "pc",
    "fp0", "fp1", "fp2", "fp3", "fp4", "fp5", "fp6", "fp7",
    "fpcontrol", "fpstatus", "fpiaddr"
  };

/* Function: m68k_register_name
   Returns the name of the standard m68k register regnum.  */

static const char *
m68k_register_name (struct gdbarch *gdbarch, int regnum)
{
  if (regnum < 0 || regnum >= ARRAY_SIZE (m68k_register_names))
    internal_error (__FILE__, __LINE__,
		    _("m68k_register_name: illegal register number %d"),
		    regnum);
  else if (regnum >= M68K_FP0_REGNUM && regnum <= M68K_FPI_REGNUM
	   && gdbarch_tdep (gdbarch)->fpregs_present == 0)
    return "";
  else
    return m68k_register_names[regnum];
}

/* Return nonzero if a value of type TYPE stored in register REGNUM
   needs any special handling.  */

static int
m68k_convert_register_p (struct gdbarch *gdbarch,
			 int regnum, struct type *type)
{
  if (!gdbarch_tdep (gdbarch)->fpregs_present)
    return 0;
  return (regnum >= M68K_FP0_REGNUM && regnum <= M68K_FP0_REGNUM + 7
	  && type != register_type (gdbarch, M68K_FP0_REGNUM));
}

/* Read a value of type TYPE from register REGNUM in frame FRAME, and
   return its contents in TO.  */

static void
m68k_register_to_value (struct frame_info *frame, int regnum,
			struct type *type, gdb_byte *to)
{
  gdb_byte from[M68K_MAX_REGISTER_SIZE];
  struct type *fpreg_type = register_type (get_frame_arch (frame),
					   M68K_FP0_REGNUM);

  /* We only support floating-point values.  */
  if (TYPE_CODE (type) != TYPE_CODE_FLT)
    {
      warning (_("Cannot convert floating-point register value "
	       "to non-floating-point type."));
      return;
    }

  /* Convert to TYPE.  */
  get_frame_register (frame, regnum, from);
  convert_typed_floating (from, fpreg_type, to, type);
}

/* Write the contents FROM of a value of type TYPE into register
   REGNUM in frame FRAME.  */

static void
m68k_value_to_register (struct frame_info *frame, int regnum,
			struct type *type, const gdb_byte *from)
{
  gdb_byte to[M68K_MAX_REGISTER_SIZE];
  struct type *fpreg_type = register_type (get_frame_arch (frame),
					   M68K_FP0_REGNUM);

  /* We only support floating-point values.  */
  if (TYPE_CODE (type) != TYPE_CODE_FLT)
    {
      warning (_("Cannot convert non-floating-point type "
	       "to floating-point register value."));
      return;
    }

  /* Convert from TYPE.  */
  convert_typed_floating (from, type, to, fpreg_type);
  put_frame_register (frame, regnum, to);
}


/* There is a fair number of calling conventions that are in somewhat
   wide use.  The 68000/08/10 don't support an FPU, not even as a
   coprocessor.  All function return values are stored in %d0/%d1.
   Structures are returned in a static buffer, a pointer to which is
   returned in %d0.  This means that functions returning a structure
   are not re-entrant.  To avoid this problem some systems use a
   convention where the caller passes a pointer to a buffer in %a1
   where the return values is to be stored.  This convention is the
   default, and is implemented in the function m68k_return_value.

   The 68020/030/040/060 do support an FPU, either as a coprocessor
   (68881/2) or built-in (68040/68060).  That's why System V release 4
   (SVR4) instroduces a new calling convention specified by the SVR4
   psABI.  Integer values are returned in %d0/%d1, pointer return
   values in %a0 and floating values in %fp0.  When calling functions
   returning a structure the caller should pass a pointer to a buffer
   for the return value in %a0.  This convention is implemented in the
   function m68k_svr4_return_value, and by appropriately setting the
   struct_value_regnum member of `struct gdbarch_tdep'.

   GNU/Linux returns values in the same way as SVR4 does, but uses %a1
   for passing the structure return value buffer.

   GCC can also generate code where small structures are returned in
   %d0/%d1 instead of in memory by using -freg-struct-return.  This is
   the default on NetBSD a.out, OpenBSD and GNU/Linux and several
   embedded systems.  This convention is implemented by setting the
   struct_return member of `struct gdbarch_tdep' to reg_struct_return.  */

/* Read a function return value of TYPE from REGCACHE, and copy that
   into VALBUF.  */

static void
m68k_extract_return_value (struct type *type, struct regcache *regcache,
			   gdb_byte *valbuf)
{
  int len = TYPE_LENGTH (type);
  gdb_byte buf[M68K_MAX_REGISTER_SIZE];

  if (len <= 4)
    {
      regcache_raw_read (regcache, M68K_D0_REGNUM, buf);
      memcpy (valbuf, buf + (4 - len), len);
    }
  else if (len <= 8)
    {
      regcache_raw_read (regcache, M68K_D0_REGNUM, buf);
      memcpy (valbuf, buf + (8 - len), len - 4);
      regcache_raw_read (regcache, M68K_D1_REGNUM, valbuf + (len - 4));
    }
  else
    internal_error (__FILE__, __LINE__,
		    _("Cannot extract return value of %d bytes long."), len);
}

static void
m68k_svr4_extract_return_value (struct type *type, struct regcache *regcache,
				gdb_byte *valbuf)
{
  int len = TYPE_LENGTH (type);
  gdb_byte buf[M68K_MAX_REGISTER_SIZE];
  struct gdbarch *gdbarch = get_regcache_arch (regcache);
  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);

  if (tdep->float_return && TYPE_CODE (type) == TYPE_CODE_FLT)
    {
      struct type *fpreg_type = register_type (gdbarch, M68K_FP0_REGNUM);
      regcache_raw_read (regcache, M68K_FP0_REGNUM, buf);
      convert_typed_floating (buf, fpreg_type, valbuf, type);
    }
  else if (TYPE_CODE (type) == TYPE_CODE_PTR && len == 4)
    regcache_raw_read (regcache, M68K_A0_REGNUM, valbuf);
  else
    m68k_extract_return_value (type, regcache, valbuf);
}

/* Write a function return value of TYPE from VALBUF into REGCACHE.  */

static void
m68k_store_return_value (struct type *type, struct regcache *regcache,
			 const gdb_byte *valbuf)
{
  int len = TYPE_LENGTH (type);

  if (len <= 4)
    regcache_raw_write_part (regcache, M68K_D0_REGNUM, 4 - len, len, valbuf);
  else if (len <= 8)
    {
      regcache_raw_write_part (regcache, M68K_D0_REGNUM, 8 - len,
			       len - 4, valbuf);
      regcache_raw_write (regcache, M68K_D1_REGNUM, valbuf + (len - 4));
    }
  else
    internal_error (__FILE__, __LINE__,
		    _("Cannot store return value of %d bytes long."), len);
}

static void
m68k_svr4_store_return_value (struct type *type, struct regcache *regcache,
			      const gdb_byte *valbuf)
{
  int len = TYPE_LENGTH (type);
  struct gdbarch *gdbarch = get_regcache_arch (regcache);
  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);

  if (tdep->float_return && TYPE_CODE (type) == TYPE_CODE_FLT)
    {
      struct type *fpreg_type = register_type (gdbarch, M68K_FP0_REGNUM);
      gdb_byte buf[M68K_MAX_REGISTER_SIZE];
      convert_typed_floating (valbuf, type, buf, fpreg_type);
      regcache_raw_write (regcache, M68K_FP0_REGNUM, buf);
    }
  else if (TYPE_CODE (type) == TYPE_CODE_PTR && len == 4)
    {
      regcache_raw_write (regcache, M68K_A0_REGNUM, valbuf);
      regcache_raw_write (regcache, M68K_D0_REGNUM, valbuf);
    }
  else
    m68k_store_return_value (type, regcache, valbuf);
}

/* Return non-zero if TYPE, which is assumed to be a structure or
   union type, should be returned in registers for architecture
   GDBARCH.  */

static int
m68k_reg_struct_return_p (struct gdbarch *gdbarch, struct type *type)
{
  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
  enum type_code code = TYPE_CODE (type);
  int len = TYPE_LENGTH (type);

  gdb_assert (code == TYPE_CODE_STRUCT || code == TYPE_CODE_UNION);

  if (tdep->struct_return == pcc_struct_return)
    return 0;

  return (len == 1 || len == 2 || len == 4 || len == 8);
}

/* Determine, for architecture GDBARCH, how a return value of TYPE
   should be returned.  If it is supposed to be returned in registers,
   and READBUF is non-zero, read the appropriate value from REGCACHE,
   and copy it into READBUF.  If WRITEBUF is non-zero, write the value
   from WRITEBUF into REGCACHE.  */

static enum return_value_convention
m68k_return_value (struct gdbarch *gdbarch, struct type *func_type,
		   struct type *type, struct regcache *regcache,
		   gdb_byte *readbuf, const gdb_byte *writebuf)
{
  enum type_code code = TYPE_CODE (type);

  /* GCC returns a `long double' in memory too.  */
  if (((code == TYPE_CODE_STRUCT || code == TYPE_CODE_UNION)
       && !m68k_reg_struct_return_p (gdbarch, type))
      || (code == TYPE_CODE_FLT && TYPE_LENGTH (type) == 12))
    {
      /* The default on m68k is to return structures in static memory.
         Consequently a function must return the address where we can
         find the return value.  */

      if (readbuf)
	{
	  ULONGEST addr;

	  regcache_raw_read_unsigned (regcache, M68K_D0_REGNUM, &addr);
	  read_memory (addr, readbuf, TYPE_LENGTH (type));
	}

      return RETURN_VALUE_ABI_RETURNS_ADDRESS;
    }

  if (readbuf)
    m68k_extract_return_value (type, regcache, readbuf);
  if (writebuf)
    m68k_store_return_value (type, regcache, writebuf);

  return RETURN_VALUE_REGISTER_CONVENTION;
}

static enum return_value_convention
m68k_svr4_return_value (struct gdbarch *gdbarch, struct type *func_type,
			struct type *type, struct regcache *regcache,
			gdb_byte *readbuf, const gdb_byte *writebuf)
{
  enum type_code code = TYPE_CODE (type);

  if ((code == TYPE_CODE_STRUCT || code == TYPE_CODE_UNION)
      && !m68k_reg_struct_return_p (gdbarch, type))
    {
      /* The System V ABI says that:

	 "A function returning a structure or union also sets %a0 to
	 the value it finds in %a0.  Thus when the caller receives
	 control again, the address of the returned object resides in
	 register %a0."

	 So the ABI guarantees that we can always find the return
	 value just after the function has returned.  */

      if (readbuf)
	{
	  ULONGEST addr;

	  regcache_raw_read_unsigned (regcache, M68K_A0_REGNUM, &addr);
	  read_memory (addr, readbuf, TYPE_LENGTH (type));
	}

      return RETURN_VALUE_ABI_RETURNS_ADDRESS;
    }

  /* This special case is for structures consisting of a single
     `float' or `double' member.  These structures are returned in
     %fp0.  For these structures, we call ourselves recursively,
     changing TYPE into the type of the first member of the structure.
     Since that should work for all structures that have only one
     member, we don't bother to check the member's type here.  */
  if (code == TYPE_CODE_STRUCT && TYPE_NFIELDS (type) == 1)
    {
      type = check_typedef (TYPE_FIELD_TYPE (type, 0));
      return m68k_svr4_return_value (gdbarch, func_type, type, regcache,
				     readbuf, writebuf);
    }

  if (readbuf)
    m68k_svr4_extract_return_value (type, regcache, readbuf);
  if (writebuf)
    m68k_svr4_store_return_value (type, regcache, writebuf);

  return RETURN_VALUE_REGISTER_CONVENTION;
}


/* Always align the frame to a 4-byte boundary.  This is required on
   coldfire and harmless on the rest.  */

static CORE_ADDR
m68k_frame_align (struct gdbarch *gdbarch, CORE_ADDR sp)
{
  /* Align the stack to four bytes.  */
  return sp & ~3;
}

static CORE_ADDR
m68k_push_dummy_call (struct gdbarch *gdbarch, struct value *function,
		      struct regcache *regcache, CORE_ADDR bp_addr, int nargs,
		      struct value **args, CORE_ADDR sp, int struct_return,
		      CORE_ADDR struct_addr)
{
  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
  gdb_byte buf[4];
  int i;

  /* Push arguments in reverse order.  */
  for (i = nargs - 1; i >= 0; i--)
    {
      struct type *value_type = value_enclosing_type (args[i]);
      int len = TYPE_LENGTH (value_type);
      int container_len = (len + 3) & ~3;
      int offset;

      /* Non-scalars bigger than 4 bytes are left aligned, others are
	 right aligned.  */
      if ((TYPE_CODE (value_type) == TYPE_CODE_STRUCT
	   || TYPE_CODE (value_type) == TYPE_CODE_UNION
	   || TYPE_CODE (value_type) == TYPE_CODE_ARRAY)
	  && len > 4)
	offset = 0;
      else
	offset = container_len - len;
      sp -= container_len;
      write_memory (sp + offset, value_contents_all (args[i]), len);
    }

  /* Store struct value address.  */
  if (struct_return)
    {
      store_unsigned_integer (buf, 4, byte_order, struct_addr);
      regcache_cooked_write (regcache, tdep->struct_value_regnum, buf);
    }

  /* Store return address.  */
  sp -= 4;
  store_unsigned_integer (buf, 4, byte_order, bp_addr);
  write_memory (sp, buf, 4);

  /* Finally, update the stack pointer...  */
  store_unsigned_integer (buf, 4, byte_order, sp);
  regcache_cooked_write (regcache, M68K_SP_REGNUM, buf);

  /* ...and fake a frame pointer.  */
  regcache_cooked_write (regcache, M68K_FP_REGNUM, buf);

  /* DWARF2/GCC uses the stack address *before* the function call as a
     frame's CFA.  */
  return sp + 8;
}

/* Convert a dwarf or dwarf2 regnumber to a GDB regnum.  */

static int
m68k_dwarf_reg_to_regnum (struct gdbarch *gdbarch, int num)
{
  if (num < 8)
    /* d0..7 */
    return (num - 0) + M68K_D0_REGNUM;
  else if (num < 16)
    /* a0..7 */
    return (num - 8) + M68K_A0_REGNUM;
  else if (num < 24 && gdbarch_tdep (gdbarch)->fpregs_present)
    /* fp0..7 */
    return (num - 16) + M68K_FP0_REGNUM;
  else if (num == 25)
    /* pc */
    return M68K_PC_REGNUM;
  else
    return gdbarch_num_regs (gdbarch) + gdbarch_num_pseudo_regs (gdbarch);
}


struct m68k_frame_cache
{
  /* Base address.  */
  CORE_ADDR base;
  CORE_ADDR sp_offset;
  CORE_ADDR pc;

  /* Saved registers.  */
  CORE_ADDR saved_regs[M68K_NUM_REGS];
  CORE_ADDR saved_sp;

  /* Stack space reserved for local variables.  */
  long locals;
};

/* Allocate and initialize a frame cache.  */

static struct m68k_frame_cache *
m68k_alloc_frame_cache (void)
{
  struct m68k_frame_cache *cache;
  int i;

  cache = FRAME_OBSTACK_ZALLOC (struct m68k_frame_cache);

  /* Base address.  */
  cache->base = 0;
  cache->sp_offset = -4;
  cache->pc = 0;

  /* Saved registers.  We initialize these to -1 since zero is a valid
     offset (that's where %fp is supposed to be stored).  */
  for (i = 0; i < M68K_NUM_REGS; i++)
    cache->saved_regs[i] = -1;

  /* Frameless until proven otherwise.  */
  cache->locals = -1;

  return cache;
}

/* Check whether PC points at a code that sets up a new stack frame.
   If so, it updates CACHE and returns the address of the first
   instruction after the sequence that sets removes the "hidden"
   argument from the stack or CURRENT_PC, whichever is smaller.
   Otherwise, return PC.  */

static CORE_ADDR
m68k_analyze_frame_setup (struct gdbarch *gdbarch,
			  CORE_ADDR pc, CORE_ADDR current_pc,
			  struct m68k_frame_cache *cache)
{
  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
  int op;

  if (pc >= current_pc)
    return current_pc;

  op = read_memory_unsigned_integer (pc, 2, byte_order);

  if (op == P_LINKW_FP || op == P_LINKL_FP || op == P_PEA_FP)
    {
      cache->saved_regs[M68K_FP_REGNUM] = 0;
      cache->sp_offset += 4;
      if (op == P_LINKW_FP)
	{
	  /* link.w %fp, #-N */
	  /* link.w %fp, #0; adda.l #-N, %sp */
	  cache->locals = -read_memory_integer (pc + 2, 2, byte_order);

	  if (pc + 4 < current_pc && cache->locals == 0)
	    {
	      op = read_memory_unsigned_integer (pc + 4, 2, byte_order);
	      if (op == P_ADDAL_SP)
		{
		  cache->locals = read_memory_integer (pc + 6, 4, byte_order);
		  return pc + 10;
		}
	    }

	  return pc + 4;
	}
      else if (op == P_LINKL_FP)
	{
	  /* link.l %fp, #-N */
	  cache->locals = -read_memory_integer (pc + 2, 4, byte_order);
	  return pc + 6;
	}
      else
	{
	  /* pea (%fp); movea.l %sp, %fp */
	  cache->locals = 0;

	  if (pc + 2 < current_pc)
	    {
	      op = read_memory_unsigned_integer (pc + 2, 2, byte_order);

	      if (op == P_MOVEAL_SP_FP)
		{
		  /* move.l %sp, %fp */
		  return pc + 4;
		}
	    }

	  return pc + 2;
	}
    }
  else if ((op & 0170777) == P_SUBQW_SP || (op & 0170777) == P_SUBQL_SP)
    {
      /* subq.[wl] #N,%sp */
      /* subq.[wl] #8,%sp; subq.[wl] #N,%sp */
      cache->locals = (op & 07000) == 0 ? 8 : (op & 07000) >> 9;
      if (pc + 2 < current_pc)
	{
	  op = read_memory_unsigned_integer (pc + 2, 2, byte_order);
	  if ((op & 0170777) == P_SUBQW_SP || (op & 0170777) == P_SUBQL_SP)
	    {
	      cache->locals += (op & 07000) == 0 ? 8 : (op & 07000) >> 9;
	      return pc + 4;
	    }
	}
      return pc + 2;
    }
  else if (op == P_ADDAW_SP || op == P_LEA_SP_SP)
    {
      /* adda.w #-N,%sp */
      /* lea (-N,%sp),%sp */
      cache->locals = -read_memory_integer (pc + 2, 2, byte_order);
      return pc + 4;
    }
  else if (op == P_ADDAL_SP)
    {
      /* adda.l #-N,%sp */
      cache->locals = -read_memory_integer (pc + 2, 4, byte_order);
      return pc + 6;
    }

  return pc;
}

/* Check whether PC points at code that saves registers on the stack.
   If so, it updates CACHE and returns the address of the first
   instruction after the register saves or CURRENT_PC, whichever is
   smaller.  Otherwise, return PC.  */

static CORE_ADDR
m68k_analyze_register_saves (struct gdbarch *gdbarch, CORE_ADDR pc,
			     CORE_ADDR current_pc,
			     struct m68k_frame_cache *cache)
{
  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);

  if (cache->locals >= 0)
    {
      CORE_ADDR offset;
      int op;
      int i, mask, regno;

      offset = -4 - cache->locals;
      while (pc < current_pc)
	{
	  op = read_memory_unsigned_integer (pc, 2, byte_order);
	  if (op == P_FMOVEMX_SP
	      && gdbarch_tdep (gdbarch)->fpregs_present)
	    {
	      /* fmovem.x REGS,-(%sp) */
	      op = read_memory_unsigned_integer (pc + 2, 2, byte_order);
	      if ((op & 0xff00) == 0xe000)
		{
		  mask = op & 0xff;
		  for (i = 0; i < 16; i++, mask >>= 1)
		    {
		      if (mask & 1)
			{
			  cache->saved_regs[i + M68K_FP0_REGNUM] = offset;
			  offset -= 12;
			}
		    }
		  pc += 4;
		}
	      else
		break;
	    }
	  else if ((op & 0177760) == P_MOVEL_SP)
	    {
	      /* move.l %R,-(%sp) */
	      regno = op & 017;
	      cache->saved_regs[regno] = offset;
	      offset -= 4;
	      pc += 2;
	    }
	  else if (op == P_MOVEML_SP)
	    {
	      /* movem.l REGS,-(%sp) */
	      mask = read_memory_unsigned_integer (pc + 2, 2, byte_order);
	      for (i = 0; i < 16; i++, mask >>= 1)
		{
		  if (mask & 1)
		    {
		      cache->saved_regs[15 - i] = offset;
		      offset -= 4;
		    }
		}
	      pc += 4;
	    }
	  else
	    break;
	}
    }

  return pc;
}


/* Do a full analysis of the prologue at PC and update CACHE
   accordingly.  Bail out early if CURRENT_PC is reached.  Return the
   address where the analysis stopped.

   We handle all cases that can be generated by gcc.

   For allocating a stack frame:

   link.w %a6,#-N
   link.l %a6,#-N
   pea (%fp); move.l %sp,%fp
   link.w %a6,#0; add.l #-N,%sp
   subq.l #N,%sp
   subq.w #N,%sp
   subq.w #8,%sp; subq.w #N-8,%sp
   add.w #-N,%sp
   lea (-N,%sp),%sp
   add.l #-N,%sp

   For saving registers:

   fmovem.x REGS,-(%sp)
   move.l R1,-(%sp)
   move.l R1,-(%sp); move.l R2,-(%sp)
   movem.l REGS,-(%sp)

   For setting up the PIC register:

   lea (%pc,N),%a5

   */

static CORE_ADDR
m68k_analyze_prologue (struct gdbarch *gdbarch, CORE_ADDR pc,
		       CORE_ADDR current_pc, struct m68k_frame_cache *cache)
{
  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
  unsigned int op;

  pc = m68k_analyze_frame_setup (gdbarch, pc, current_pc, cache);
  pc = m68k_analyze_register_saves (gdbarch, pc, current_pc, cache);
  if (pc >= current_pc)
    return current_pc;

  /* Check for GOT setup.  */
  op = read_memory_unsigned_integer (pc, 4, byte_order);
  if (op == P_LEA_PC_A5)
    {
      /* lea (%pc,N),%a5 */
      return pc + 8;
    }

  return pc;
}

/* Return PC of first real instruction.  */

static CORE_ADDR
m68k_skip_prologue (struct gdbarch *gdbarch, CORE_ADDR start_pc)
{
  struct m68k_frame_cache cache;
  CORE_ADDR pc;
  int op;

  cache.locals = -1;
  pc = m68k_analyze_prologue (gdbarch, start_pc, (CORE_ADDR) -1, &cache);
  if (cache.locals < 0)
    return start_pc;
  return pc;
}

static CORE_ADDR
m68k_unwind_pc (struct gdbarch *gdbarch, struct frame_info *next_frame)
{
  gdb_byte buf[8];

  frame_unwind_register (next_frame, gdbarch_pc_regnum (gdbarch), buf);
  return extract_typed_address (buf, builtin_type (gdbarch)->builtin_func_ptr);
}

/* Normal frames.  */

static struct m68k_frame_cache *
m68k_frame_cache (struct frame_info *this_frame, void **this_cache)
{
  struct gdbarch *gdbarch = get_frame_arch (this_frame);
  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
  struct m68k_frame_cache *cache;
  gdb_byte buf[4];
  int i;

  if (*this_cache)
    return *this_cache;

  cache = m68k_alloc_frame_cache ();
  *this_cache = cache;

  /* In principle, for normal frames, %fp holds the frame pointer,
     which holds the base address for the current stack frame.
     However, for functions that don't need it, the frame pointer is
     optional.  For these "frameless" functions the frame pointer is
     actually the frame pointer of the calling frame.  Signal
     trampolines are just a special case of a "frameless" function.
     They (usually) share their frame pointer with the frame that was
     in progress when the signal occurred.  */

  get_frame_register (this_frame, M68K_FP_REGNUM, buf);
  cache->base = extract_unsigned_integer (buf, 4, byte_order);
  if (cache->base == 0)
    return cache;

  /* For normal frames, %pc is stored at 4(%fp).  */
  cache->saved_regs[M68K_PC_REGNUM] = 4;

  cache->pc = get_frame_func (this_frame);
  if (cache->pc != 0)
    m68k_analyze_prologue (get_frame_arch (this_frame), cache->pc,
			   get_frame_pc (this_frame), cache);

  if (cache->locals < 0)
    {
      /* We didn't find a valid frame, which means that CACHE->base
	 currently holds the frame pointer for our calling frame.  If
	 we're at the start of a function, or somewhere half-way its
	 prologue, the function's frame probably hasn't been fully
	 setup yet.  Try to reconstruct the base address for the stack
	 frame by looking at the stack pointer.  For truly "frameless"
	 functions this might work too.  */

      get_frame_register (this_frame, M68K_SP_REGNUM, buf);
      cache->base = extract_unsigned_integer (buf, 4, byte_order)
		    + cache->sp_offset;
    }

  /* Now that we have the base address for the stack frame we can
     calculate the value of %sp in the calling frame.  */
  cache->saved_sp = cache->base + 8;

  /* Adjust all the saved registers such that they contain addresses
     instead of offsets.  */
  for (i = 0; i < M68K_NUM_REGS; i++)
    if (cache->saved_regs[i] != -1)
      cache->saved_regs[i] += cache->base;

  return cache;
}

static void
m68k_frame_this_id (struct frame_info *this_frame, void **this_cache,
		    struct frame_id *this_id)
{
  struct m68k_frame_cache *cache = m68k_frame_cache (this_frame, this_cache);

  /* This marks the outermost frame.  */
  if (cache->base == 0)
    return;

  /* See the end of m68k_push_dummy_call.  */
  *this_id = frame_id_build (cache->base + 8, cache->pc);
}

static struct value *
m68k_frame_prev_register (struct frame_info *this_frame, void **this_cache,
			  int regnum)
{
  struct m68k_frame_cache *cache = m68k_frame_cache (this_frame, this_cache);

  gdb_assert (regnum >= 0);

  if (regnum == M68K_SP_REGNUM && cache->saved_sp)
    return frame_unwind_got_constant (this_frame, regnum, cache->saved_sp);

  if (regnum < M68K_NUM_REGS && cache->saved_regs[regnum] != -1)
    return frame_unwind_got_memory (this_frame, regnum,
				    cache->saved_regs[regnum]);

  return frame_unwind_got_register (this_frame, regnum, regnum);
}

static const struct frame_unwind m68k_frame_unwind =
{
  NORMAL_FRAME,
  m68k_frame_this_id,
  m68k_frame_prev_register,
  NULL,
  default_frame_sniffer
};

static CORE_ADDR
m68k_frame_base_address (struct frame_info *this_frame, void **this_cache)
{
  struct m68k_frame_cache *cache = m68k_frame_cache (this_frame, this_cache);

  return cache->base;
}

static const struct frame_base m68k_frame_base =
{
  &m68k_frame_unwind,
  m68k_frame_base_address,
  m68k_frame_base_address,
  m68k_frame_base_address
};

static struct frame_id
m68k_dummy_id (struct gdbarch *gdbarch, struct frame_info *this_frame)
{
  CORE_ADDR fp;

  fp = get_frame_register_unsigned (this_frame, M68K_FP_REGNUM);

  /* See the end of m68k_push_dummy_call.  */
  return frame_id_build (fp + 8, get_frame_pc (this_frame));
}


/* Figure out where the longjmp will land.  Slurp the args out of the stack.
   We expect the first arg to be a pointer to the jmp_buf structure from which
   we extract the pc (JB_PC) that we will land at.  The pc is copied into PC.
   This routine returns true on success.  */

static int
m68k_get_longjmp_target (struct frame_info *frame, CORE_ADDR *pc)
{
  gdb_byte *buf;
  CORE_ADDR sp, jb_addr;
  struct gdbarch *gdbarch = get_frame_arch (frame);
  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);

  if (tdep->jb_pc < 0)
    {
      internal_error (__FILE__, __LINE__,
		      _("m68k_get_longjmp_target: not implemented"));
      return 0;
    }

  buf = alloca (gdbarch_ptr_bit (gdbarch) / TARGET_CHAR_BIT);
  sp = get_frame_register_unsigned (frame, gdbarch_sp_regnum (gdbarch));

  if (target_read_memory (sp + SP_ARG0,	/* Offset of first arg on stack.  */
			  buf, gdbarch_ptr_bit (gdbarch) / TARGET_CHAR_BIT))
    return 0;

  jb_addr = extract_unsigned_integer (buf, gdbarch_ptr_bit (gdbarch)
					     / TARGET_CHAR_BIT, byte_order);

  if (target_read_memory (jb_addr + tdep->jb_pc * tdep->jb_elt_size, buf,
			  gdbarch_ptr_bit (gdbarch) / TARGET_CHAR_BIT),
			  byte_order)
    return 0;

  *pc = extract_unsigned_integer (buf, gdbarch_ptr_bit (gdbarch)
					 / TARGET_CHAR_BIT, byte_order);
  return 1;
}


/* System V Release 4 (SVR4).  */

void
m68k_svr4_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
{
  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);

  /* SVR4 uses a different calling convention.  */
  set_gdbarch_return_value (gdbarch, m68k_svr4_return_value);

  /* SVR4 uses %a0 instead of %a1.  */
  tdep->struct_value_regnum = M68K_A0_REGNUM;
}


/* Function: m68k_gdbarch_init
   Initializer function for the m68k gdbarch vector.
   Called by gdbarch.  Sets up the gdbarch vector(s) for this target.  */

static struct gdbarch *
m68k_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
{
  struct gdbarch_tdep *tdep = NULL;
  struct gdbarch *gdbarch;
  struct gdbarch_list *best_arch;
  struct tdesc_arch_data *tdesc_data = NULL;
  int i;
  enum m68k_flavour flavour = m68k_no_flavour;
  int has_fp = 1;
  const struct floatformat **long_double_format = floatformats_m68881_ext;

  /* Check any target description for validity.  */
  if (tdesc_has_registers (info.target_desc))
    {
      const struct tdesc_feature *feature;
      int valid_p;

      feature = tdesc_find_feature (info.target_desc,
				    "org.gnu.gdb.m68k.core");
      if (feature != NULL)
	/* Do nothing.  */
	;

      if (feature == NULL)
	{
	  feature = tdesc_find_feature (info.target_desc,
					"org.gnu.gdb.coldfire.core");
	  if (feature != NULL)
	    flavour = m68k_coldfire_flavour;
	}

      if (feature == NULL)
	{
	  feature = tdesc_find_feature (info.target_desc,
					"org.gnu.gdb.fido.core");
	  if (feature != NULL)
	    flavour = m68k_fido_flavour;
	}

      if (feature == NULL)
	return NULL;

      tdesc_data = tdesc_data_alloc ();

      valid_p = 1;
      for (i = 0; i <= M68K_PC_REGNUM; i++)
	valid_p &= tdesc_numbered_register (feature, tdesc_data, i,
					    m68k_register_names[i]);

      if (!valid_p)
	{
	  tdesc_data_cleanup (tdesc_data);
	  return NULL;
	}

      feature = tdesc_find_feature (info.target_desc,
				    "org.gnu.gdb.coldfire.fp");
      if (feature != NULL)
	{
	  valid_p = 1;
	  for (i = M68K_FP0_REGNUM; i <= M68K_FPI_REGNUM; i++)
	    valid_p &= tdesc_numbered_register (feature, tdesc_data, i,
						m68k_register_names[i]);
	  if (!valid_p)
	    {
	      tdesc_data_cleanup (tdesc_data);
	      return NULL;
	    }
	}
      else
	has_fp = 0;
    }

  /* The mechanism for returning floating values from function
     and the type of long double depend on whether we're
     on ColdFire or standard m68k.  */

  if (info.bfd_arch_info && info.bfd_arch_info->mach != 0)
    {
      const bfd_arch_info_type *coldfire_arch = 
	bfd_lookup_arch (bfd_arch_m68k, bfd_mach_mcf_isa_a_nodiv);

      if (coldfire_arch
	  && ((*info.bfd_arch_info->compatible) 
	      (info.bfd_arch_info, coldfire_arch)))
	flavour = m68k_coldfire_flavour;
    }
  
  /* If there is already a candidate, use it.  */
  for (best_arch = gdbarch_list_lookup_by_info (arches, &info);
       best_arch != NULL;
       best_arch = gdbarch_list_lookup_by_info (best_arch->next, &info))
    {
      if (flavour != gdbarch_tdep (best_arch->gdbarch)->flavour)
	continue;

      if (has_fp != gdbarch_tdep (best_arch->gdbarch)->fpregs_present)
	continue;

      break;
    }

  if (best_arch != NULL)
    {
      if (tdesc_data != NULL)
	tdesc_data_cleanup (tdesc_data);
      return best_arch->gdbarch;
    }

  tdep = xzalloc (sizeof (struct gdbarch_tdep));
  gdbarch = gdbarch_alloc (&info, tdep);
  tdep->fpregs_present = has_fp;
  tdep->flavour = flavour;

  if (flavour == m68k_coldfire_flavour || flavour == m68k_fido_flavour)
    long_double_format = floatformats_ieee_double;
  set_gdbarch_long_double_format (gdbarch, long_double_format);
  set_gdbarch_long_double_bit (gdbarch, long_double_format[0]->totalsize);

  set_gdbarch_skip_prologue (gdbarch, m68k_skip_prologue);
  set_gdbarch_breakpoint_from_pc (gdbarch, m68k_local_breakpoint_from_pc);

  /* Stack grows down.  */
  set_gdbarch_inner_than (gdbarch, core_addr_lessthan);
  set_gdbarch_frame_align (gdbarch, m68k_frame_align);

  set_gdbarch_believe_pcc_promotion (gdbarch, 1);
  if (flavour == m68k_coldfire_flavour || flavour == m68k_fido_flavour)
    set_gdbarch_decr_pc_after_break (gdbarch, 2);

  set_gdbarch_frame_args_skip (gdbarch, 8);
  set_gdbarch_dwarf2_reg_to_regnum (gdbarch, m68k_dwarf_reg_to_regnum);

  set_gdbarch_register_type (gdbarch, m68k_register_type);
  set_gdbarch_register_name (gdbarch, m68k_register_name);
  set_gdbarch_num_regs (gdbarch, M68K_NUM_REGS);
  set_gdbarch_sp_regnum (gdbarch, M68K_SP_REGNUM);
  set_gdbarch_pc_regnum (gdbarch, M68K_PC_REGNUM);
  set_gdbarch_ps_regnum (gdbarch, M68K_PS_REGNUM);
  set_gdbarch_convert_register_p (gdbarch, m68k_convert_register_p);
  set_gdbarch_register_to_value (gdbarch,  m68k_register_to_value);
  set_gdbarch_value_to_register (gdbarch, m68k_value_to_register);

  if (has_fp)
    set_gdbarch_fp0_regnum (gdbarch, M68K_FP0_REGNUM);

  /* Try to figure out if the arch uses floating registers to return
     floating point values from functions.  */
  if (has_fp)
    {
      /* On ColdFire, floating point values are returned in D0.  */
      if (flavour == m68k_coldfire_flavour)
	tdep->float_return = 0;
      else
	tdep->float_return = 1;
    }
  else
    {
      /* No floating registers, so can't use them for returning values.  */
      tdep->float_return = 0;
    }

  /* Function call & return.  */
  set_gdbarch_push_dummy_call (gdbarch, m68k_push_dummy_call);
  set_gdbarch_return_value (gdbarch, m68k_return_value);


  /* Disassembler.  */
  set_gdbarch_print_insn (gdbarch, print_insn_m68k);

#if defined JB_PC && defined JB_ELEMENT_SIZE
  tdep->jb_pc = JB_PC;
  tdep->jb_elt_size = JB_ELEMENT_SIZE;
#else
  tdep->jb_pc = -1;
#endif
  tdep->struct_value_regnum = M68K_A1_REGNUM;
  tdep->struct_return = reg_struct_return;

  /* Frame unwinder.  */
  set_gdbarch_dummy_id (gdbarch, m68k_dummy_id);
  set_gdbarch_unwind_pc (gdbarch, m68k_unwind_pc);

  /* Hook in the DWARF CFI frame unwinder.  */
  dwarf2_append_unwinders (gdbarch);

  frame_base_set_default (gdbarch, &m68k_frame_base);

  /* Hook in ABI-specific overrides, if they have been registered.  */
  gdbarch_init_osabi (info, gdbarch);

  /* Now we have tuned the configuration, set a few final things,
     based on what the OS ABI has told us.  */

  if (tdep->jb_pc >= 0)
    set_gdbarch_get_longjmp_target (gdbarch, m68k_get_longjmp_target);

  frame_unwind_append_unwinder (gdbarch, &m68k_frame_unwind);

  if (tdesc_data)
    tdesc_use_registers (gdbarch, info.target_desc, tdesc_data);

  return gdbarch;
}


static void
m68k_dump_tdep (struct gdbarch *gdbarch, struct ui_file *file)
{
  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);

  if (tdep == NULL)
    return;
}

extern initialize_file_ftype _initialize_m68k_tdep; /* -Wmissing-prototypes */

void
_initialize_m68k_tdep (void)
{
  gdbarch_register (bfd_arch_m68k, m68k_gdbarch_init, m68k_dump_tdep);
}