summaryrefslogtreecommitdiff
path: root/gdb/m68k-tdep.c
blob: d9dc17141ee19b57ef889ae35d8557bc72a58707 (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
/* Target dependent code for the Motorola 68000 series.
   Copyright 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1999, 2000, 2001
   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., 59 Temple Place - Suite 330,
   Boston, MA 02111-1307, USA.  */

#include "defs.h"
#include "frame.h"
#include "symtab.h"
#include "gdbcore.h"
#include "value.h"
#include "gdb_string.h"
#include "inferior.h"
#include "regcache.h"


#define P_LINKL_FP	0x480e
#define P_LINKW_FP	0x4e56
#define P_PEA_FP	0x4856
#define P_MOVL_SP_FP	0x2c4f
#define P_MOVL		0x207c
#define P_JSR		0x4eb9
#define P_BSR		0x61ff
#define P_LEAL		0x43fb
#define P_MOVML		0x48ef
#define P_FMOVM		0xf237
#define P_TRAP		0x4e40

/* The only reason this is here is the tm-altos.h reference below.  It
   was moved back here from tm-m68k.h.  FIXME? */

extern CORE_ADDR
altos_skip_prologue (CORE_ADDR pc)
{
  register int op = read_memory_integer (pc, 2);
  if (op == P_LINKW_FP)
    pc += 4;			/* Skip link #word */
  else if (op == P_LINKL_FP)
    pc += 6;			/* Skip link #long */
  /* Not sure why branches are here.  */
  /* From tm-isi.h, tm-altos.h */
  else if (op == 0060000)
    pc += 4;			/* Skip bra #word */
  else if (op == 00600377)
    pc += 6;			/* skip bra #long */
  else if ((op & 0177400) == 0060000)
    pc += 2;			/* skip bra #char */
  return pc;
}

/* The only reason this is here is the tm-isi.h reference below.  It
   was moved back here from tm-m68k.h.  FIXME? */

extern CORE_ADDR
isi_skip_prologue (CORE_ADDR pc)
{
  register int op = read_memory_integer (pc, 2);
  if (op == P_LINKW_FP)
    pc += 4;			/* Skip link #word */
  else if (op == P_LINKL_FP)
    pc += 6;			/* Skip link #long */
  /* Not sure why branches are here.  */
  /* From tm-isi.h, tm-altos.h */
  else if (op == 0060000)
    pc += 4;			/* Skip bra #word */
  else if (op == 00600377)
    pc += 6;			/* skip bra #long */
  else if ((op & 0177400) == 0060000)
    pc += 2;			/* skip bra #char */
  return pc;
}

int
delta68_in_sigtramp (CORE_ADDR pc, char *name)
{
  if (name != NULL)
    return strcmp (name, "_sigcode") == 0;
  else
    return 0;
}

CORE_ADDR
delta68_frame_args_address (struct frame_info *frame_info)
{
  /* we assume here that the only frameless functions are the system calls
     or other functions who do not put anything on the stack. */
  if (frame_info->signal_handler_caller)
    return frame_info->frame + 12;
  else if (frameless_look_for_prologue (frame_info))
    {
    /* Check for an interrupted system call */
    if (frame_info->next && frame_info->next->signal_handler_caller)
      return frame_info->next->frame + 16;
    else
      return frame_info->frame + 4;
    }
  else
    return frame_info->frame;
}

CORE_ADDR
delta68_frame_saved_pc (struct frame_info *frame_info)
{
  return read_memory_integer (delta68_frame_args_address (frame_info) + 4, 4);
}

/* Return number of args passed to a frame.
   Can return -1, meaning no way to tell.  */

int
isi_frame_num_args (struct frame_info *fi)
{
  int val;
  CORE_ADDR pc = FRAME_SAVED_PC (fi);
  int insn = 0177777 & read_memory_integer (pc, 2);
  val = 0;
  if (insn == 0047757 || insn == 0157374)	/* lea W(sp),sp or addaw #W,sp */
    val = read_memory_integer (pc + 2, 2);
  else if ((insn & 0170777) == 0050217	/* addql #N, sp */
	   || (insn & 0170777) == 0050117)	/* addqw */
    {
      val = (insn >> 9) & 7;
      if (val == 0)
	val = 8;
    }
  else if (insn == 0157774)	/* addal #WW, sp */
    val = read_memory_integer (pc + 2, 4);
  val >>= 2;
  return val;
}

int
delta68_frame_num_args (struct frame_info *fi)
{
  int val;
  CORE_ADDR pc = FRAME_SAVED_PC (fi);
  int insn = 0177777 & read_memory_integer (pc, 2);
  val = 0;
  if (insn == 0047757 || insn == 0157374)	/* lea W(sp),sp or addaw #W,sp */
    val = read_memory_integer (pc + 2, 2);
  else if ((insn & 0170777) == 0050217	/* addql #N, sp */
	   || (insn & 0170777) == 0050117)	/* addqw */
    {
      val = (insn >> 9) & 7;
      if (val == 0)
	val = 8;
    }
  else if (insn == 0157774)	/* addal #WW, sp */
    val = read_memory_integer (pc + 2, 4);
  val >>= 2;
  return val;
}

int
news_frame_num_args (struct frame_info *fi)
{
  int val;
  CORE_ADDR pc = FRAME_SAVED_PC (fi);
  int insn = 0177777 & read_memory_integer (pc, 2);
  val = 0;
  if (insn == 0047757 || insn == 0157374)	/* lea W(sp),sp or addaw #W,sp */
    val = read_memory_integer (pc + 2, 2);
  else if ((insn & 0170777) == 0050217	/* addql #N, sp */
	   || (insn & 0170777) == 0050117)	/* addqw */
    {
      val = (insn >> 9) & 7;
      if (val == 0)
	val = 8;
    }
  else if (insn == 0157774)	/* addal #WW, sp */
    val = read_memory_integer (pc + 2, 4);
  val >>= 2;
  return val;
}

/* Push an empty stack frame, to record the current PC, etc.  */

void
m68k_push_dummy_frame (void)
{
  register CORE_ADDR sp = read_register (SP_REGNUM);
  register int regnum;
  char raw_buffer[12];

  sp = push_word (sp, read_register (PC_REGNUM));
  sp = push_word (sp, read_register (FP_REGNUM));
  write_register (FP_REGNUM, sp);

  /* Always save the floating-point registers, whether they exist on
     this target or not.  */
  for (regnum = FP0_REGNUM + 7; regnum >= FP0_REGNUM; regnum--)
    {
      read_register_bytes (REGISTER_BYTE (regnum), raw_buffer, 12);
      sp = push_bytes (sp, raw_buffer, 12);
    }

  for (regnum = FP_REGNUM - 1; regnum >= 0; regnum--)
    {
      sp = push_word (sp, read_register (regnum));
    }
  sp = push_word (sp, read_register (PS_REGNUM));
  write_register (SP_REGNUM, sp);
}

/* Discard from the stack the innermost frame,
   restoring all saved registers.  */

void
m68k_pop_frame (void)
{
  register struct frame_info *frame = get_current_frame ();
  register CORE_ADDR fp;
  register int regnum;
  struct frame_saved_regs fsr;
  char raw_buffer[12];

  fp = FRAME_FP (frame);
  get_frame_saved_regs (frame, &fsr);
  for (regnum = FP0_REGNUM + 7; regnum >= FP0_REGNUM; regnum--)
    {
      if (fsr.regs[regnum])
	{
	  read_memory (fsr.regs[regnum], raw_buffer, 12);
	  write_register_bytes (REGISTER_BYTE (regnum), raw_buffer, 12);
	}
    }
  for (regnum = FP_REGNUM - 1; regnum >= 0; regnum--)
    {
      if (fsr.regs[regnum])
	{
	  write_register (regnum, read_memory_integer (fsr.regs[regnum], 4));
	}
    }
  if (fsr.regs[PS_REGNUM])
    {
      write_register (PS_REGNUM, read_memory_integer (fsr.regs[PS_REGNUM], 4));
    }
  write_register (FP_REGNUM, read_memory_integer (fp, 4));
  write_register (PC_REGNUM, read_memory_integer (fp + 4, 4));
  write_register (SP_REGNUM, fp + 8);
  flush_cached_frames ();
}


/* Given an ip value corresponding to the start of a function,
   return the ip of the first instruction after the function 
   prologue.  This is the generic m68k support.  Machines which
   require something different can override the SKIP_PROLOGUE
   macro to point elsewhere.

   Some instructions which typically may appear in a function
   prologue include:

   A link instruction, word form:

   link.w       %a6,&0                  4e56  XXXX

   A link instruction, long form:

   link.l  %fp,&F%1             480e  XXXX  XXXX

   A movm instruction to preserve integer regs:

   movm.l  &M%1,(4,%sp)         48ef  XXXX  XXXX

   A fmovm instruction to preserve float regs:

   fmovm   &FPM%1,(FPO%1,%sp)   f237  XXXX  XXXX  XXXX  XXXX

   Some profiling setup code (FIXME, not recognized yet):

   lea.l   (.L3,%pc),%a1                43fb  XXXX  XXXX  XXXX
   bsr     _mcount                      61ff  XXXX  XXXX

 */

CORE_ADDR
m68k_skip_prologue (CORE_ADDR ip)
{
  register CORE_ADDR limit;
  struct symtab_and_line sal;
  register int op;

  /* Find out if there is a known limit for the extent of the prologue.
     If so, ensure we don't go past it.  If not, assume "infinity". */

  sal = find_pc_line (ip, 0);
  limit = (sal.end) ? sal.end : (CORE_ADDR) ~ 0;

  while (ip < limit)
    {
      op = read_memory_integer (ip, 2);
      op &= 0xFFFF;

      if (op == P_LINKW_FP)
	ip += 4;		/* Skip link.w */
      else if (op == P_PEA_FP)
	ip += 2;		/* Skip pea %fp */
      else if (op == P_MOVL_SP_FP)
	ip += 2;		/* Skip move.l %sp, %fp */
      else if (op == P_LINKL_FP)
	ip += 6;		/* Skip link.l */
      else if (op == P_MOVML)
	ip += 6;		/* Skip movm.l */
      else if (op == P_FMOVM)
	ip += 10;		/* Skip fmovm */
      else
	break;		/* Found unknown code, bail out. */
    }
  return (ip);
}

void
m68k_find_saved_regs (struct frame_info *frame_info,
		      struct frame_saved_regs *saved_regs)
{
  register int regnum;
  register int regmask;
  register CORE_ADDR next_addr;
  register CORE_ADDR pc;

  /* First possible address for a pc in a call dummy for this frame.  */
  CORE_ADDR possible_call_dummy_start =
  (frame_info)->frame - CALL_DUMMY_LENGTH - FP_REGNUM * 4 - 4 - 8 * 12;

  int nextinsn;
  memset (saved_regs, 0, sizeof (*saved_regs));
  if ((frame_info)->pc >= possible_call_dummy_start
      && (frame_info)->pc <= (frame_info)->frame)
    {

      /* It is a call dummy.  We could just stop now, since we know
         what the call dummy saves and where.  But this code proceeds
         to parse the "prologue" which is part of the call dummy.
         This is needlessly complex and confusing.  FIXME.  */

      next_addr = (frame_info)->frame;
      pc = possible_call_dummy_start;
    }
  else
    {
      pc = get_pc_function_start ((frame_info)->pc);

      nextinsn = read_memory_integer (pc, 2);
      if (P_PEA_FP == nextinsn
	  && P_MOVL_SP_FP == read_memory_integer (pc + 2, 2))
	{
	  /* pea %fp
	     move.l %sp, %fp */
	  next_addr = frame_info->frame;
	  pc += 4;
	}
      else if (P_LINKL_FP == nextinsn)
	/* link.l %fp */
	/* Find the address above the saved   
	   regs using the amount of storage from the link instruction.  */
	{
	  next_addr = (frame_info)->frame + read_memory_integer (pc + 2, 4);
	  pc += 6;
	}
      else if (P_LINKW_FP == nextinsn)
	/* link.w %fp */
	/* Find the address above the saved   
	   regs using the amount of storage from the link instruction.  */
	{
	  next_addr = (frame_info)->frame + read_memory_integer (pc + 2, 2);
	  pc += 4;
	}
      else
	goto lose;

      /* If have an addal #-n, sp next, adjust next_addr.  */
      if ((0177777 & read_memory_integer (pc, 2)) == 0157774)
	next_addr += read_memory_integer (pc += 2, 4), pc += 4;
    }

  for ( ; ; )
    {
      nextinsn = 0xffff & read_memory_integer (pc, 2);
      regmask = read_memory_integer (pc + 2, 2);
      /* fmovemx to -(sp) */
      if (0xf227 == nextinsn && (regmask & 0xff00) == 0xe000)
	{
	  /* Regmask's low bit is for register fp7, the first pushed */
	  for (regnum = FP0_REGNUM + 8; --regnum >= FP0_REGNUM; regmask >>= 1)
	    if (regmask & 1)
	      saved_regs->regs[regnum] = (next_addr -= 12);
	  pc += 4;
	}
      /* fmovemx to (fp + displacement) */
      else if (0171056 == nextinsn && (regmask & 0xff00) == 0xf000)
	{
	  register CORE_ADDR addr;

	  addr = (frame_info)->frame + read_memory_integer (pc + 4, 2);
	  /* Regmask's low bit is for register fp7, the first pushed */
	  for (regnum = FP0_REGNUM + 8; --regnum >= FP0_REGNUM; regmask >>= 1)
	    if (regmask & 1)
	      {
		saved_regs->regs[regnum] = addr;
		addr += 12;
	      }
	  pc += 6;
	}
      /* moveml to (sp) */
      else if (0044327 == nextinsn)
	{
	  /* Regmask's low bit is for register 0, the first written */
	  for (regnum = 0; regnum < 16; regnum++, regmask >>= 1)
	    if (regmask & 1)
	      {
		saved_regs->regs[regnum] = next_addr;
		next_addr += 4;
	      }
	  pc += 4;
	}
      /* moveml to (fp + displacement) */
      else if (0044356 == nextinsn)
	{
	  register CORE_ADDR addr;

	  addr = (frame_info)->frame + read_memory_integer (pc + 4, 2);
	  /* Regmask's low bit is for register 0, the first written */
	  for (regnum = 0; regnum < 16; regnum++, regmask >>= 1)
	    if (regmask & 1)
	      {
		saved_regs->regs[regnum] = addr;
		addr += 4;
	      }
	  pc += 6;
	}
      /* moveml to -(sp) */
      else if (0044347 == nextinsn)
	{
	  /* Regmask's low bit is for register 15, the first pushed */
	  for (regnum = 16; --regnum >= 0; regmask >>= 1)
	    if (regmask & 1)
	      saved_regs->regs[regnum] = (next_addr -= 4);
	  pc += 4;
	}
      /* movl r,-(sp) */
      else if (0x2f00 == (0xfff0 & nextinsn))
	{
	  regnum = 0xf & nextinsn;
	  saved_regs->regs[regnum] = (next_addr -= 4);
	  pc += 2;
	}
      /* fmovemx to index of sp */
      else if (0xf236 == nextinsn && (regmask & 0xff00) == 0xf000)
	{
	  /* Regmask's low bit is for register fp0, the first written */
	  for (regnum = FP0_REGNUM + 8; --regnum >= FP0_REGNUM; regmask >>= 1)
	    if (regmask & 1)
	      {
		saved_regs->regs[regnum] = next_addr;
		next_addr += 12;
	      }
	  pc += 10;
	}
      /* clrw -(sp); movw ccr,-(sp) */
      else if (0x4267 == nextinsn && 0x42e7 == regmask)
	{
	  saved_regs->regs[PS_REGNUM] = (next_addr -= 4);
	  pc += 4;
	}
      else
	break;
    }
lose:;
  saved_regs->regs[SP_REGNUM] = (frame_info)->frame + 8;
  saved_regs->regs[FP_REGNUM] = (frame_info)->frame;
  saved_regs->regs[PC_REGNUM] = (frame_info)->frame + 4;
#ifdef SIG_SP_FP_OFFSET
  /* Adjust saved SP_REGNUM for fake _sigtramp frames.  */
  if (frame_info->signal_handler_caller && frame_info->next)
    saved_regs->regs[SP_REGNUM] = frame_info->next->frame + SIG_SP_FP_OFFSET;
#endif
}


#ifdef USE_PROC_FS		/* Target dependent support for /proc */

#include <sys/procfs.h>

/* Prototypes for supply_gregset etc. */
#include "gregset.h"

/*  The /proc interface divides the target machine's register set up into
   two different sets, the general register set (gregset) and the floating
   point register set (fpregset).  For each set, there is an ioctl to get
   the current register set and another ioctl to set the current values.

   The actual structure passed through the ioctl interface is, of course,
   naturally machine dependent, and is different for each set of registers.
   For the m68k for example, the general register set is typically defined
   by:

   typedef int gregset_t[18];

   #define      R_D0    0
   ...
   #define      R_PS    17

   and the floating point set by:

   typedef      struct fpregset {
   int  f_pcr;
   int  f_psr;
   int  f_fpiaddr;
   int  f_fpregs[8][3];         (8 regs, 96 bits each)
   } fpregset_t;

   These routines provide the packing and unpacking of gregset_t and
   fpregset_t formatted data.

 */

/* Atari SVR4 has R_SR but not R_PS */

#if !defined (R_PS) && defined (R_SR)
#define R_PS R_SR
#endif

/*  Given a pointer to a general register set in /proc format (gregset_t *),
   unpack the register contents and supply them as gdb's idea of the current
   register values. */

void
supply_gregset (gregset_t *gregsetp)
{
  register int regi;
  register greg_t *regp = (greg_t *) gregsetp;

  for (regi = 0; regi < R_PC; regi++)
    {
      supply_register (regi, (char *) (regp + regi));
    }
  supply_register (PS_REGNUM, (char *) (regp + R_PS));
  supply_register (PC_REGNUM, (char *) (regp + R_PC));
}

void
fill_gregset (gregset_t *gregsetp, int regno)
{
  register int regi;
  register greg_t *regp = (greg_t *) gregsetp;

  for (regi = 0; regi < R_PC; regi++)
    {
      if ((regno == -1) || (regno == regi))
	{
	  *(regp + regi) = *(int *) &registers[REGISTER_BYTE (regi)];
	}
    }
  if ((regno == -1) || (regno == PS_REGNUM))
    {
      *(regp + R_PS) = *(int *) &registers[REGISTER_BYTE (PS_REGNUM)];
    }
  if ((regno == -1) || (regno == PC_REGNUM))
    {
      *(regp + R_PC) = *(int *) &registers[REGISTER_BYTE (PC_REGNUM)];
    }
}

#if defined (FP0_REGNUM)

/*  Given a pointer to a floating point register set in /proc format
   (fpregset_t *), unpack the register contents and supply them as gdb's
   idea of the current floating point register values. */

void
supply_fpregset (fpregset_t *fpregsetp)
{
  register int regi;
  char *from;

  for (regi = FP0_REGNUM; regi < FPC_REGNUM; regi++)
    {
      from = (char *) &(fpregsetp->f_fpregs[regi - FP0_REGNUM][0]);
      supply_register (regi, from);
    }
  supply_register (FPC_REGNUM, (char *) &(fpregsetp->f_pcr));
  supply_register (FPS_REGNUM, (char *) &(fpregsetp->f_psr));
  supply_register (FPI_REGNUM, (char *) &(fpregsetp->f_fpiaddr));
}

/*  Given a pointer to a floating point register set in /proc format
   (fpregset_t *), update the register specified by REGNO from gdb's idea
   of the current floating point register set.  If REGNO is -1, update
   them all. */

void
fill_fpregset (fpregset_t *fpregsetp, int regno)
{
  int regi;
  char *to;
  char *from;

  for (regi = FP0_REGNUM; regi < FPC_REGNUM; regi++)
    {
      if ((regno == -1) || (regno == regi))
	{
	  from = (char *) &registers[REGISTER_BYTE (regi)];
	  to = (char *) &(fpregsetp->f_fpregs[regi - FP0_REGNUM][0]);
	  memcpy (to, from, REGISTER_RAW_SIZE (regi));
	}
    }
  if ((regno == -1) || (regno == FPC_REGNUM))
    {
      fpregsetp->f_pcr = *(int *) &registers[REGISTER_BYTE (FPC_REGNUM)];
    }
  if ((regno == -1) || (regno == FPS_REGNUM))
    {
      fpregsetp->f_psr = *(int *) &registers[REGISTER_BYTE (FPS_REGNUM)];
    }
  if ((regno == -1) || (regno == FPI_REGNUM))
    {
      fpregsetp->f_fpiaddr = *(int *) &registers[REGISTER_BYTE (FPI_REGNUM)];
    }
}

#endif /* defined (FP0_REGNUM) */

#endif /* USE_PROC_FS */

/* 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. */

/* NOTE: cagney/2000-11-08: For this function to be fully multi-arched
   the macro's JB_PC and JB_ELEMENT_SIZE would need to be moved into
   the ``struct gdbarch_tdep'' object and then set on a target ISA/ABI
   dependant basis. */

int
m68k_get_longjmp_target (CORE_ADDR *pc)
{
#if defined (JB_PC) && defined (JB_ELEMENT_SIZE)
  char *buf;
  CORE_ADDR sp, jb_addr;

  buf = alloca (TARGET_PTR_BIT / TARGET_CHAR_BIT);
  sp = read_register (SP_REGNUM);

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

  jb_addr = extract_address (buf, TARGET_PTR_BIT / TARGET_CHAR_BIT);

  if (target_read_memory (jb_addr + JB_PC * JB_ELEMENT_SIZE, buf,
			  TARGET_PTR_BIT / TARGET_CHAR_BIT))
    return 0;

  *pc = extract_address (buf, TARGET_PTR_BIT / TARGET_CHAR_BIT);

  return 1;
#else
  internal_error (__FILE__, __LINE__,
		  "m68k_get_longjmp_target: not implemented");
  return 0;
#endif
}

/* Immediately after a function call, return the saved pc before the frame
   is setup.  For sun3's, we check for the common case of being inside of a
   system call, and if so, we know that Sun pushes the call # on the stack
   prior to doing the trap. */

CORE_ADDR
m68k_saved_pc_after_call (struct frame_info *frame)
{
#ifdef SYSCALL_TRAP
  int op;

  op = read_memory_integer (frame->pc - SYSCALL_TRAP_OFFSET, 2);

  if (op == SYSCALL_TRAP)
    return read_memory_integer (read_register (SP_REGNUM) + 4, 4);
  else
#endif /* SYSCALL_TRAP */
    return read_memory_integer (read_register (SP_REGNUM), 4);
}


void
_initialize_m68k_tdep (void)
{
  tm_print_insn = print_insn_m68k;
}