aboutsummaryrefslogtreecommitdiff
path: root/gdb/mn10200-tdep.c
blob: 808f7e4e3a549c1d3e29e6c2b1b2005b79a0f63f (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
/* Target-dependent code for the Matsushita MN10200 for GDB, the GNU debugger.
   Copyright 1997, 1998, 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 "inferior.h"
#include "target.h"
#include "value.h"
#include "bfd.h"
#include "gdb_string.h"
#include "gdbcore.h"
#include "symfile.h"
#include "regcache.h"


/* Should call_function allocate stack space for a struct return?  */
int
mn10200_use_struct_convention (int gcc_p, struct type *type)
{
  return (TYPE_NFIELDS (type) > 1 || TYPE_LENGTH (type) > 8);
}
/* *INDENT-OFF* */
/* The main purpose of this file is dealing with prologues to extract
   information about stack frames and saved registers.

   For reference here's how prologues look on the mn10200:

     With frame pointer:
	mov fp,a0
	mov sp,fp
	add <size>,sp
	Register saves for d2, d3, a1, a2 as needed.  Saves start
	at fp - <size> + <outgoing_args_size> and work towards higher
	addresses.  Note that the saves are actually done off the stack
	pointer in the prologue!  This makes for smaller code and easier
	prologue scanning as the displacement fields will unlikely
        be more than 8 bits!

     Without frame pointer:
        add <size>,sp
	Register saves for d2, d3, a1, a2 as needed.  Saves start
	at sp + <outgoing_args_size> and work towards higher addresses.

     Out of line prologue:
	add <local size>,sp  -- optional
	jsr __prologue
	add <outgoing_size>,sp -- optional

   The stack pointer remains constant throughout the life of most
   functions.  As a result the compiler will usually omit the
   frame pointer, so we must handle frame pointerless functions.  */

/* Analyze the prologue to determine where registers are saved,
   the end of the prologue, etc etc.  Return the end of the prologue
   scanned.

   We store into FI (if non-null) several tidbits of information:

    * stack_size -- size of this stack frame.  Note that if we stop in
    certain parts of the prologue/epilogue we may claim the size of the
    current frame is zero.  This happens when the current frame has
    not been allocated yet or has already been deallocated.

    * fsr -- Addresses of registers saved in the stack by this frame.

    * status -- A (relatively) generic status indicator.  It's a bitmask
    with the following bits: 

      MY_FRAME_IN_SP: The base of the current frame is actually in
      the stack pointer.  This can happen for frame pointerless
      functions, or cases where we're stopped in the prologue/epilogue
      itself.  For these cases mn10200_analyze_prologue will need up
      update fi->frame before returning or analyzing the register
      save instructions.

      MY_FRAME_IN_FP: The base of the current frame is in the
      frame pointer register ($a2).

      CALLER_A2_IN_A0: $a2 from the caller's frame is temporarily
      in $a0.  This can happen if we're stopped in the prologue.

      NO_MORE_FRAMES: Set this if the current frame is "start" or
      if the first instruction looks like mov <imm>,sp.  This tells
      frame chain to not bother trying to unwind past this frame.  */
/* *INDENT-ON* */




#define MY_FRAME_IN_SP 0x1
#define MY_FRAME_IN_FP 0x2
#define CALLER_A2_IN_A0 0x4
#define NO_MORE_FRAMES 0x8

static CORE_ADDR
mn10200_analyze_prologue (struct frame_info *fi, CORE_ADDR pc)
{
  CORE_ADDR func_addr, func_end, addr, stop;
  CORE_ADDR stack_size = 0;
  unsigned char buf[4];
  int status;
  char *name;
  int out_of_line_prologue = 0;

  /* Use the PC in the frame if it's provided to look up the
     start of this function.  */
  pc = (fi ? get_frame_pc (fi) : pc);

  /* Find the start of this function.  */
  status = find_pc_partial_function (pc, &name, &func_addr, &func_end);

  /* Do nothing if we couldn't find the start of this function or if we're
     stopped at the first instruction in the prologue.  */
  if (status == 0)
    return pc;

  /* If we're in start, then give up.  */
  if (strcmp (name, "start") == 0)
    {
      if (fi)
	fi->status = NO_MORE_FRAMES;
      return pc;
    }

  /* At the start of a function our frame is in the stack pointer.  */
  if (fi)
    fi->status = MY_FRAME_IN_SP;

  /* If we're physically on an RTS instruction, then our frame has already
     been deallocated.

     fi->frame is bogus, we need to fix it.  */
  if (fi && get_frame_pc (fi) + 1 == func_end)
    {
      status = target_read_memory (get_frame_pc (fi), buf, 1);
      if (status != 0)
	{
	  if (fi->next == NULL)
	    deprecated_update_frame_base_hack (fi, read_sp ());
	  return get_frame_pc (fi);
	}

      if (buf[0] == 0xfe)
	{
	  if (fi->next == NULL)
	    deprecated_update_frame_base_hack (fi, read_sp ());
	  return get_frame_pc (fi);
	}
    }

  /* Similarly if we're stopped on the first insn of a prologue as our
     frame hasn't been allocated yet.  */
  if (fi && get_frame_pc (fi) == func_addr)
    {
      if (fi->next == NULL)
	deprecated_update_frame_base_hack (fi, read_sp ());
      return get_frame_pc (fi);
    }

  /* Figure out where to stop scanning.  */
  stop = fi ? get_frame_pc (fi) : func_end;

  /* Don't walk off the end of the function.  */
  stop = stop > func_end ? func_end : stop;

  /* Start scanning on the first instruction of this function.  */
  addr = func_addr;

  status = target_read_memory (addr, buf, 2);
  if (status != 0)
    {
      if (fi && fi->next == NULL && fi->status & MY_FRAME_IN_SP)
	deprecated_update_frame_base_hack (fi, read_sp ());
      return addr;
    }

  /* First see if this insn sets the stack pointer; if so, it's something
     we won't understand, so quit now.   */
  if (buf[0] == 0xdf
      || (buf[0] == 0xf4 && buf[1] == 0x77))
    {
      if (fi)
	fi->status = NO_MORE_FRAMES;
      return addr;
    }

  /* Now see if we have a frame pointer.

     Search for mov a2,a0 (0xf278)
     then       mov a3,a2 (0xf27e).  */

  if (buf[0] == 0xf2 && buf[1] == 0x78)
    {
      /* Our caller's $a2 will be found in $a0 now.  Note it for
         our callers.  */
      if (fi)
	fi->status |= CALLER_A2_IN_A0;
      addr += 2;
      if (addr >= stop)
	{
	  /* We still haven't allocated our local stack.  Handle this
	     as if we stopped on the first or last insn of a function.   */
	  if (fi && fi->next == NULL)
	    deprecated_update_frame_base_hack (fi, read_sp ());
	  return addr;
	}

      status = target_read_memory (addr, buf, 2);
      if (status != 0)
	{
	  if (fi && fi->next == NULL)
	    deprecated_update_frame_base_hack (fi, read_sp ());
	  return addr;
	}
      if (buf[0] == 0xf2 && buf[1] == 0x7e)
	{
	  addr += 2;

	  /* Our frame pointer is valid now.  */
	  if (fi)
	    {
	      fi->status |= MY_FRAME_IN_FP;
	      fi->status &= ~MY_FRAME_IN_SP;
	    }
	  if (addr >= stop)
	    return addr;
	}
      else
	{
	  if (fi && fi->next == NULL)
	    deprecated_update_frame_base_hack (fi, read_sp ());
	  return addr;
	}
    }

  /* Next we should allocate the local frame.

     Search for add imm8,a3 (0xd3XX)
     or add imm16,a3 (0xf70bXXXX)
     or add imm24,a3 (0xf467XXXXXX).

     If none of the above was found, then this prologue has
     no stack, and therefore can't have any register saves,
     so quit now.  */
  status = target_read_memory (addr, buf, 2);
  if (status != 0)
    {
      if (fi && fi->next == NULL && (fi->status & MY_FRAME_IN_SP))
	deprecated_update_frame_base_hack (fi, read_sp ());
      return addr;
    }
  if (buf[0] == 0xd3)
    {
      stack_size = extract_signed_integer (&buf[1], 1);
      if (fi)
	fi->stack_size = stack_size;
      addr += 2;
      if (addr >= stop)
	{
	  if (fi && fi->next == NULL && (fi->status & MY_FRAME_IN_SP))
	    deprecated_update_frame_base_hack (fi, read_sp () - stack_size);
	  return addr;
	}
    }
  else if (buf[0] == 0xf7 && buf[1] == 0x0b)
    {
      status = target_read_memory (addr + 2, buf, 2);
      if (status != 0)
	{
	  if (fi && fi->next == NULL && (fi->status & MY_FRAME_IN_SP))
	    deprecated_update_frame_base_hack (fi, read_sp ());
	  return addr;
	}
      stack_size = extract_signed_integer (buf, 2);
      if (fi)
	fi->stack_size = stack_size;
      addr += 4;
      if (addr >= stop)
	{
	  if (fi && fi->next == NULL && (fi->status & MY_FRAME_IN_SP))
	    deprecated_update_frame_base_hack (fi, read_sp () - stack_size);
	  return addr;
	}
    }
  else if (buf[0] == 0xf4 && buf[1] == 0x67)
    {
      status = target_read_memory (addr + 2, buf, 3);
      if (status != 0)
	{
	  if (fi && fi->next == NULL && (fi->status & MY_FRAME_IN_SP))
	    deprecated_update_frame_base_hack (fi, read_sp ());
	  return addr;
	}
      stack_size = extract_signed_integer (buf, 3);
      if (fi)
	fi->stack_size = stack_size;
      addr += 5;
      if (addr >= stop)
	{
	  if (fi && fi->next == NULL && (fi->status & MY_FRAME_IN_SP))
	    deprecated_update_frame_base_hack (fi, read_sp () - stack_size);
	  return addr;
	}
    }

  /* Now see if we have a call to __prologue for an out of line
     prologue.  */
  status = target_read_memory (addr, buf, 2);
  if (status != 0)
    return addr;

  /* First check for 16bit pc-relative call to __prologue.  */
  if (buf[0] == 0xfd)
    {
      CORE_ADDR temp;
      status = target_read_memory (addr + 1, buf, 2);
      if (status != 0)
	{
	  if (fi && fi->next == NULL && (fi->status & MY_FRAME_IN_SP))
	    deprecated_update_frame_base_hack (fi, read_sp ());
	  return addr;
	}

      /* Get the PC this instruction will branch to.  */
      temp = (extract_signed_integer (buf, 2) + addr + 3) & 0xffffff;

      /* Get the name of the function at the target address.  */
      status = find_pc_partial_function (temp, &name, NULL, NULL);
      if (status == 0)
	{
	  if (fi && fi->next == NULL && (fi->status & MY_FRAME_IN_SP))
	    deprecated_update_frame_base_hack (fi, read_sp ());
	  return addr;
	}

      /* Note if it is an out of line prologue.  */
      out_of_line_prologue = (strcmp (name, "__prologue") == 0);

      /* This sucks up 3 bytes of instruction space.  */
      if (out_of_line_prologue)
	addr += 3;

      if (addr >= stop)
	{
	  if (fi && fi->next == NULL)
	    {
	      fi->stack_size -= 16;
	      deprecated_update_frame_base_hack (fi, read_sp () - fi->stack_size);
	    }
	  return addr;
	}
    }
  /* Now check for the 24bit pc-relative call to __prologue.  */
  else if (buf[0] == 0xf4 && buf[1] == 0xe1)
    {
      CORE_ADDR temp;
      status = target_read_memory (addr + 2, buf, 3);
      if (status != 0)
	{
	  if (fi && fi->next == NULL && (fi->status & MY_FRAME_IN_SP))
	    deprecated_update_frame_base_hack (fi, read_sp ());
	  return addr;
	}

      /* Get the PC this instruction will branch to.  */
      temp = (extract_signed_integer (buf, 3) + addr + 5) & 0xffffff;

      /* Get the name of the function at the target address.  */
      status = find_pc_partial_function (temp, &name, NULL, NULL);
      if (status == 0)
	{
	  if (fi && fi->next == NULL && (fi->status & MY_FRAME_IN_SP))
	    deprecated_update_frame_base_hack (fi, read_sp ());
	  return addr;
	}

      /* Note if it is an out of line prologue.  */
      out_of_line_prologue = (strcmp (name, "__prologue") == 0);

      /* This sucks up 5 bytes of instruction space.  */
      if (out_of_line_prologue)
	addr += 5;

      if (addr >= stop)
	{
	  if (fi && fi->next == NULL && (fi->status & MY_FRAME_IN_SP))
	    {
	      fi->stack_size -= 16;
	      deprecated_update_frame_base_hack (fi, read_sp () - fi->stack_size);
	    }
	  return addr;
	}
    }

  /* Now actually handle the out of line prologue.  */
  if (out_of_line_prologue)
    {
      int outgoing_args_size = 0;

      /* First adjust the stack size for this function.  The out of
         line prologue saves 4 registers (16bytes of data).  */
      if (fi)
	fi->stack_size -= 16;

      /* Update fi->frame if necessary.  */
      if (fi && fi->next == NULL)
	deprecated_update_frame_base_hack (fi, read_sp () - fi->stack_size);

      /* After the out of line prologue, there may be another
         stack adjustment for the outgoing arguments.

         Search for add imm8,a3 (0xd3XX)
         or     add imm16,a3 (0xf70bXXXX)
         or     add imm24,a3 (0xf467XXXXXX).  */

      status = target_read_memory (addr, buf, 2);
      if (status != 0)
	{
	  if (fi)
	    {
	      fi->fsr.regs[2] = fi->frame + fi->stack_size + 4;
	      fi->fsr.regs[3] = fi->frame + fi->stack_size + 8;
	      fi->fsr.regs[5] = fi->frame + fi->stack_size + 12;
	      fi->fsr.regs[6] = fi->frame + fi->stack_size + 16;
	    }
	  return addr;
	}

      if (buf[0] == 0xd3)
	{
	  outgoing_args_size = extract_signed_integer (&buf[1], 1);
	  addr += 2;
	}
      else if (buf[0] == 0xf7 && buf[1] == 0x0b)
	{
	  status = target_read_memory (addr + 2, buf, 2);
	  if (status != 0)
	    {
	      if (fi)
		{
		  fi->fsr.regs[2] = fi->frame + fi->stack_size + 4;
		  fi->fsr.regs[3] = fi->frame + fi->stack_size + 8;
		  fi->fsr.regs[5] = fi->frame + fi->stack_size + 12;
		  fi->fsr.regs[6] = fi->frame + fi->stack_size + 16;
		}
	      return addr;
	    }
	  outgoing_args_size = extract_signed_integer (buf, 2);
	  addr += 4;
	}
      else if (buf[0] == 0xf4 && buf[1] == 0x67)
	{
	  status = target_read_memory (addr + 2, buf, 3);
	  if (status != 0)
	    {
	      if (fi && fi->next == NULL)
		{
		  fi->fsr.regs[2] = fi->frame + fi->stack_size + 4;
		  fi->fsr.regs[3] = fi->frame + fi->stack_size + 8;
		  fi->fsr.regs[5] = fi->frame + fi->stack_size + 12;
		  fi->fsr.regs[6] = fi->frame + fi->stack_size + 16;
		}
	      return addr;
	    }
	  outgoing_args_size = extract_signed_integer (buf, 3);
	  addr += 5;
	}
      else
	outgoing_args_size = 0;

      /* Now that we know the size of the outgoing arguments, fix
         fi->frame again if this is the innermost frame.  */
      if (fi && fi->next == NULL)
	deprecated_update_frame_base_hack (fi, fi->frame - outgoing_args_size);

      /* Note the register save information and update the stack
         size for this frame too.  */
      if (fi)
	{
	  fi->fsr.regs[2] = fi->frame + fi->stack_size + 4;
	  fi->fsr.regs[3] = fi->frame + fi->stack_size + 8;
	  fi->fsr.regs[5] = fi->frame + fi->stack_size + 12;
	  fi->fsr.regs[6] = fi->frame + fi->stack_size + 16;
	  fi->stack_size += outgoing_args_size;
	}
      /* There can be no more prologue insns, so return now.  */
      return addr;
    }

  /* At this point fi->frame needs to be correct.

     If MY_FRAME_IN_SP is set and we're the innermost frame, then we
     need to fix fi->frame so that backtracing, find_frame_saved_regs,
     etc work correctly.  */
  if (fi && fi->next == NULL && (fi->status & MY_FRAME_IN_SP) != 0)
    deprecated_update_frame_base_hack (fi, read_sp () - fi->stack_size);

  /* And last we have the register saves.  These are relatively
     simple because they're physically done off the stack pointer,
     and thus the number of different instructions we need to
     check is greatly reduced because we know the displacements
     will be small.

     Search for movx d2,(X,a3) (0xf55eXX)
     then       movx d3,(X,a3) (0xf55fXX)
     then       mov  a1,(X,a3) (0x5dXX)    No frame pointer case
     then       mov  a2,(X,a3) (0x5eXX)    No frame pointer case
     or  mov  a0,(X,a3) (0x5cXX)           Frame pointer case.  */

  status = target_read_memory (addr, buf, 2);
  if (status != 0)
    return addr;
  if (buf[0] == 0xf5 && buf[1] == 0x5e)
    {
      if (fi)
	{
	  status = target_read_memory (addr + 2, buf, 1);
	  if (status != 0)
	    return addr;
	  fi->fsr.regs[2] = (fi->frame + stack_size
			     + extract_signed_integer (buf, 1));
	}
      addr += 3;
      if (addr >= stop)
	return addr;
      status = target_read_memory (addr, buf, 2);
      if (status != 0)
	return addr;
    }
  if (buf[0] == 0xf5 && buf[1] == 0x5f)
    {
      if (fi)
	{
	  status = target_read_memory (addr + 2, buf, 1);
	  if (status != 0)
	    return addr;
	  fi->fsr.regs[3] = (fi->frame + stack_size
			     + extract_signed_integer (buf, 1));
	}
      addr += 3;
      if (addr >= stop)
	return addr;
      status = target_read_memory (addr, buf, 2);
      if (status != 0)
	return addr;
    }
  if (buf[0] == 0x5d)
    {
      if (fi)
	{
	  status = target_read_memory (addr + 1, buf, 1);
	  if (status != 0)
	    return addr;
	  fi->fsr.regs[5] = (fi->frame + stack_size
			     + extract_signed_integer (buf, 1));
	}
      addr += 2;
      if (addr >= stop)
	return addr;
      status = target_read_memory (addr, buf, 2);
      if (status != 0)
	return addr;
    }
  if (buf[0] == 0x5e || buf[0] == 0x5c)
    {
      if (fi)
	{
	  status = target_read_memory (addr + 1, buf, 1);
	  if (status != 0)
	    return addr;
	  fi->fsr.regs[6] = (fi->frame + stack_size
			     + extract_signed_integer (buf, 1));
	  fi->status &= ~CALLER_A2_IN_A0;
	}
      addr += 2;
      if (addr >= stop)
	return addr;
      return addr;
    }
  return addr;
}

/* Function: frame_chain
   Figure out and return the caller's frame pointer given current
   frame_info struct.

   We don't handle dummy frames yet but we would probably just return the
   stack pointer that was in use at the time the function call was made?  */

CORE_ADDR
mn10200_frame_chain (struct frame_info *fi)
{
  struct frame_info *dummy_frame = deprecated_frame_xmalloc ();
  struct cleanup *old_chain = make_cleanup (xfree, dummy_frame);
  CORE_ADDR ret;

  /* Walk through the prologue to determine the stack size,
     location of saved registers, end of the prologue, etc.  */
  if (fi->status == 0)
    mn10200_analyze_prologue (fi, (CORE_ADDR) 0);

  /* Quit now if mn10200_analyze_prologue set NO_MORE_FRAMES.  */
  if (fi->status & NO_MORE_FRAMES)
    return 0;

  /* Now that we've analyzed our prologue, determine the frame
     pointer for our caller.

     If our caller has a frame pointer, then we need to
     find the entry value of $a2 to our function.

     If CALLER_A2_IN_A0, then the chain is in $a0.

     If fsr.regs[6] is nonzero, then it's at the memory
     location pointed to by fsr.regs[6].

     Else it's still in $a2.

     If our caller does not have a frame pointer, then his
     frame base is fi->frame + -caller's stack size + 4.  */

  /* The easiest way to get that info is to analyze our caller's frame.

     So we set up a dummy frame and call mn10200_analyze_prologue to
     find stuff for us.  */
  deprecated_update_frame_pc_hack (dummy_frame, FRAME_SAVED_PC (fi));
  deprecated_update_frame_base_hack (dummy_frame, fi->frame);
  memset (dummy_frame->fsr.regs, '\000', sizeof dummy_frame->fsr.regs);
  dummy_frame->status = 0;
  dummy_frame->stack_size = 0;
  mn10200_analyze_prologue (dummy_frame, 0);

  if (dummy_frame->status & MY_FRAME_IN_FP)
    {
      /* Our caller has a frame pointer.  So find the frame in $a2, $a0,
         or in the stack.  */
      if (fi->fsr.regs[6])
	ret = (read_memory_integer (fi->fsr.regs[FP_REGNUM], REGISTER_SIZE)
	       & 0xffffff);
      else if (fi->status & CALLER_A2_IN_A0)
	ret = read_register (4);
      else
	ret = read_register (FP_REGNUM);
    }
  else
    {
      /* Our caller does not have a frame pointer.  So his frame starts
         at the base of our frame (fi->frame) + <his size> + 4 (saved pc).  */
      ret = fi->frame + -dummy_frame->stack_size + 4;
    }
  do_cleanups (old_chain);
  return ret;
}

/* Function: skip_prologue
   Return the address of the first inst past the prologue of the function.  */

CORE_ADDR
mn10200_skip_prologue (CORE_ADDR pc)
{
  /* We used to check the debug symbols, but that can lose if
     we have a null prologue.  */
  return mn10200_analyze_prologue (NULL, pc);
}

/* Function: pop_frame
   This routine gets called when either the user uses the `return'
   command, or the call dummy breakpoint gets hit.  */

void
mn10200_pop_frame (struct frame_info *frame)
{
  int regnum;

  if (DEPRECATED_PC_IN_CALL_DUMMY (get_frame_pc (frame), frame->frame, frame->frame))
    generic_pop_dummy_frame ();
  else
    {
      write_register (PC_REGNUM, FRAME_SAVED_PC (frame));

      /* Restore any saved registers.  */
      for (regnum = 0; regnum < NUM_REGS; regnum++)
	if (frame->fsr.regs[regnum] != 0)
	  {
	    ULONGEST value;

	    value = read_memory_unsigned_integer (frame->fsr.regs[regnum],
						REGISTER_RAW_SIZE (regnum));
	    write_register (regnum, value);
	  }

      /* Actually cut back the stack.  */
      write_register (SP_REGNUM, get_frame_base (frame));

      /* Don't we need to set the PC?!?  XXX FIXME.  */
    }

  /* Throw away any cached frame information.  */
  flush_cached_frames ();
}

/* Function: push_arguments
   Setup arguments for a call to the target.  Arguments go in
   order on the stack.  */

CORE_ADDR
mn10200_push_arguments (int nargs, struct value **args, CORE_ADDR sp,
			unsigned char struct_return, CORE_ADDR struct_addr)
{
  int argnum = 0;
  int len = 0;
  int stack_offset = 0;
  int regsused = struct_return ? 1 : 0;

  /* This should be a nop, but align the stack just in case something
     went wrong.  Stacks are two byte aligned on the mn10200.  */
  sp &= ~1;

  /* Now make space on the stack for the args.

     XXX This doesn't appear to handle pass-by-invisible reference
     arguments.  */
  for (argnum = 0; argnum < nargs; argnum++)
    {
      int arg_length = (TYPE_LENGTH (VALUE_TYPE (args[argnum])) + 1) & ~1;

      /* If we've used all argument registers, then this argument is
         pushed.  */
      if (regsused >= 2 || arg_length > 4)
	{
	  regsused = 2;
	  len += arg_length;
	}
      /* We know we've got some arg register space left.  If this argument
         will fit entirely in regs, then put it there.  */
      else if (arg_length <= 2
	       || TYPE_CODE (VALUE_TYPE (args[argnum])) == TYPE_CODE_PTR)
	{
	  regsused++;
	}
      else if (regsused == 0)
	{
	  regsused = 2;
	}
      else
	{
	  regsused = 2;
	  len += arg_length;
	}
    }

  /* Allocate stack space.  */
  sp -= len;

  regsused = struct_return ? 1 : 0;
  /* Push all arguments onto the stack. */
  for (argnum = 0; argnum < nargs; argnum++)
    {
      int len;
      char *val;

      /* XXX Check this.  What about UNIONS?  */
      if (TYPE_CODE (VALUE_TYPE (*args)) == TYPE_CODE_STRUCT
	  && TYPE_LENGTH (VALUE_TYPE (*args)) > 8)
	{
	  /* XXX Wrong, we want a pointer to this argument.  */
	  len = TYPE_LENGTH (VALUE_TYPE (*args));
	  val = (char *) VALUE_CONTENTS (*args);
	}
      else
	{
	  len = TYPE_LENGTH (VALUE_TYPE (*args));
	  val = (char *) VALUE_CONTENTS (*args);
	}

      if (regsused < 2
	  && (len <= 2
	      || TYPE_CODE (VALUE_TYPE (*args)) == TYPE_CODE_PTR))
	{
	  write_register (regsused, extract_unsigned_integer (val, 4));
	  regsused++;
	}
      else if (regsused == 0 && len == 4)
	{
	  write_register (regsused, extract_unsigned_integer (val, 2));
	  write_register (regsused + 1, extract_unsigned_integer (val + 2, 2));
	  regsused = 2;
	}
      else
	{
	  regsused = 2;
	  while (len > 0)
	    {
	      write_memory (sp + stack_offset, val, 2);

	      len -= 2;
	      val += 2;
	      stack_offset += 2;
	    }
	}
      args++;
    }

  return sp;
}

/* Function: push_return_address (pc)
   Set up the return address for the inferior function call.
   Needed for targets where we don't actually execute a JSR/BSR instruction */

CORE_ADDR
mn10200_push_return_address (CORE_ADDR pc, CORE_ADDR sp)
{
  unsigned char buf[4];

  store_unsigned_integer (buf, 4, CALL_DUMMY_ADDRESS ());
  write_memory (sp - 4, buf, 4);
  return sp - 4;
}

/* Function: store_struct_return (addr,sp)
   Store the structure value return address for an inferior function
   call.  */

CORE_ADDR
mn10200_store_struct_return (CORE_ADDR addr, CORE_ADDR sp)
{
  /* The structure return address is passed as the first argument.  */
  write_register (0, addr);
  return sp;
}

/* Function: frame_saved_pc 
   Find the caller of this frame.  We do this by seeing if RP_REGNUM
   is saved in the stack anywhere, otherwise we get it from the
   registers.  If the inner frame is a dummy frame, return its PC
   instead of RP, because that's where "caller" of the dummy-frame
   will be found.  */

CORE_ADDR
mn10200_frame_saved_pc (struct frame_info *fi)
{
  /* The saved PC will always be at the base of the current frame.  */
  return (read_memory_integer (fi->frame, REGISTER_SIZE) & 0xffffff);
}

/* Function: init_extra_frame_info
   Setup the frame's frame pointer, pc, and frame addresses for saved
   registers.  Most of the work is done in mn10200_analyze_prologue().

   Note that when we are called for the last frame (currently active frame),
   that get_frame_pc (fi) and fi->frame will already be setup.  However, fi->frame will
   be valid only if this routine uses FP.  For previous frames, fi-frame will
   always be correct.  mn10200_analyze_prologue will fix fi->frame if
   it's not valid.

   We can be called with the PC in the call dummy under two circumstances.
   First, during normal backtracing, second, while figuring out the frame
   pointer just prior to calling the target function (see run_stack_dummy).  */

void
mn10200_init_extra_frame_info (struct frame_info *fi)
{
  if (fi->next)
    deprecated_update_frame_pc_hack (fi, FRAME_SAVED_PC (fi->next));

  memset (fi->fsr.regs, '\000', sizeof fi->fsr.regs);
  fi->status = 0;
  fi->stack_size = 0;

  mn10200_analyze_prologue (fi, 0);
}

void
_initialize_mn10200_tdep (void)
{
  tm_print_insn = print_insn_mn10200;
}