aboutsummaryrefslogtreecommitdiff
path: root/gdb/avr-tdep.c
blob: 3d8711f494e9c709dd9596b94014248759443a1d (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
/* Target-dependent code for Atmel AVR, for GDB.
   Copyright 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003
   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.  */

/* Contributed by Theodore A. Roth, troth@verinet.com */

/* Portions of this file were taken from the original gdb-4.18 patch developed
   by Denis Chertykov, denisc@overta.ru */

#include "defs.h"
#include "gdbcmd.h"
#include "gdbcore.h"
#include "inferior.h"
#include "symfile.h"
#include "arch-utils.h"
#include "regcache.h"
#include "gdb_string.h"

/* AVR Background:

   (AVR micros are pure Harvard Architecture processors.)

   The AVR family of microcontrollers have three distinctly different memory
   spaces: flash, sram and eeprom. The flash is 16 bits wide and is used for
   the most part to store program instructions. The sram is 8 bits wide and is
   used for the stack and the heap. Some devices lack sram and some can have
   an additional external sram added on as a peripheral.

   The eeprom is 8 bits wide and is used to store data when the device is
   powered down. Eeprom is not directly accessible, it can only be accessed
   via io-registers using a special algorithm. Accessing eeprom via gdb's
   remote serial protocol ('m' or 'M' packets) looks difficult to do and is
   not included at this time.

   [The eeprom could be read manually via ``x/b <eaddr + AVR_EMEM_START>'' or
   written using ``set {unsigned char}<eaddr + AVR_EMEM_START>''.  For this to
   work, the remote target must be able to handle eeprom accesses and perform
   the address translation.]

   All three memory spaces have physical addresses beginning at 0x0. In
   addition, the flash is addressed by gcc/binutils/gdb with respect to 8 bit
   bytes instead of the 16 bit wide words used by the real device for the
   Program Counter.

   In order for remote targets to work correctly, extra bits must be added to
   addresses before they are send to the target or received from the target
   via the remote serial protocol. The extra bits are the MSBs and are used to
   decode which memory space the address is referring to. */

#undef XMALLOC
#define XMALLOC(TYPE) ((TYPE*) xmalloc (sizeof (TYPE)))

#undef EXTRACT_INSN
#define EXTRACT_INSN(addr) extract_unsigned_integer(addr,2)

/* Constants: prefixed with AVR_ to avoid name space clashes */

enum
{
  AVR_REG_W = 24,
  AVR_REG_X = 26,
  AVR_REG_Y = 28,
  AVR_FP_REGNUM = 28,
  AVR_REG_Z = 30,

  AVR_SREG_REGNUM = 32,
  AVR_SP_REGNUM = 33,
  AVR_PC_REGNUM = 34,

  AVR_NUM_REGS = 32 + 1 /*SREG*/ + 1 /*SP*/ + 1 /*PC*/,
  AVR_NUM_REG_BYTES = 32 + 1 /*SREG*/ + 2 /*SP*/ + 4 /*PC*/,

  AVR_PC_REG_INDEX = 35,	/* index into array of registers */

  AVR_MAX_PROLOGUE_SIZE = 56,	/* bytes */

  /* Count of pushed registers. From r2 to r17 (inclusively), r28, r29 */
  AVR_MAX_PUSHES = 18,

  /* Number of the last pushed register. r17 for current avr-gcc */
  AVR_LAST_PUSHED_REGNUM = 17,

  /* FIXME: TRoth/2002-01-??: Can we shift all these memory masks left 8
     bits? Do these have to match the bfd vma values?. It sure would make
     things easier in the future if they didn't need to match.

     Note: I chose these values so as to be consistent with bfd vma
     addresses.

     TRoth/2002-04-08: There is already a conflict with very large programs
     in the mega128. The mega128 has 128K instruction bytes (64K words),
     thus the Most Significant Bit is 0x10000 which gets masked off my
     AVR_MEM_MASK.

     The problem manifests itself when trying to set a breakpoint in a
     function which resides in the upper half of the instruction space and
     thus requires a 17-bit address.

     For now, I've just removed the EEPROM mask and changed AVR_MEM_MASK
     from 0x00ff0000 to 0x00f00000. Eeprom is not accessible from gdb yet,
     but could be for some remote targets by just adding the correct offset
     to the address and letting the remote target handle the low-level
     details of actually accessing the eeprom. */

  AVR_IMEM_START = 0x00000000,	/* INSN memory */
  AVR_SMEM_START = 0x00800000,	/* SRAM memory */
#if 1
  /* No eeprom mask defined */
  AVR_MEM_MASK = 0x00f00000,	/* mask to determine memory space */
#else
  AVR_EMEM_START = 0x00810000,	/* EEPROM memory */
  AVR_MEM_MASK = 0x00ff0000,	/* mask to determine memory space */
#endif
};

/* Any function with a frame looks like this
   .......    <-SP POINTS HERE
   LOCALS1    <-FP POINTS HERE
   LOCALS0
   SAVED FP
   SAVED R3
   SAVED R2
   RET PC
   FIRST ARG
   SECOND ARG */

struct frame_extra_info
{
  CORE_ADDR return_pc;
  CORE_ADDR args_pointer;
  int locals_size;
  int framereg;
  int framesize;
  int is_main;
};

struct gdbarch_tdep
{
  /* FIXME: TRoth: is there anything to put here? */
  int foo;
};

/* Lookup the name of a register given it's number. */

static const char *
avr_register_name (int regnum)
{
  static char *register_names[] = {
    "r0", "r1", "r2", "r3", "r4", "r5", "r6", "r7",
    "r8", "r9", "r10", "r11", "r12", "r13", "r14", "r15",
    "r16", "r17", "r18", "r19", "r20", "r21", "r22", "r23",
    "r24", "r25", "r26", "r27", "r28", "r29", "r30", "r31",
    "SREG", "SP", "PC"
  };
  if (regnum < 0)
    return NULL;
  if (regnum >= (sizeof (register_names) / sizeof (*register_names)))
    return NULL;
  return register_names[regnum];
}

/* Index within `registers' of the first byte of the space for
   register REGNUM.  */

static int
avr_register_byte (int regnum)
{
  if (regnum < AVR_PC_REGNUM)
    return regnum;
  else
    return AVR_PC_REG_INDEX;
}

/* Number of bytes of storage in the actual machine representation for
   register REGNUM.  */

static int
avr_register_raw_size (int regnum)
{
  switch (regnum)
    {
    case AVR_PC_REGNUM:
      return 4;
    case AVR_SP_REGNUM:
    case AVR_FP_REGNUM:
      return 2;
    default:
      return 1;
    }
}

/* Number of bytes of storage in the program's representation
   for register N.  */

static int
avr_register_virtual_size (int regnum)
{
  return TYPE_LENGTH (REGISTER_VIRTUAL_TYPE (regnum));
}

/* Return the GDB type object for the "standard" data type
   of data in register N.  */

static struct type *
avr_register_virtual_type (int regnum)
{
  switch (regnum)
    {
    case AVR_PC_REGNUM:
      return builtin_type_unsigned_long;
    case AVR_SP_REGNUM:
      return builtin_type_unsigned_short;
    default:
      return builtin_type_unsigned_char;
    }
}

/* Instruction address checks and convertions. */

static CORE_ADDR
avr_make_iaddr (CORE_ADDR x)
{
  return ((x) | AVR_IMEM_START);
}

static int
avr_iaddr_p (CORE_ADDR x)
{
  return (((x) & AVR_MEM_MASK) == AVR_IMEM_START);
}

/* FIXME: TRoth: Really need to use a larger mask for instructions. Some
   devices are already up to 128KBytes of flash space.

   TRoth/2002-04-8: See comment above where AVR_IMEM_START is defined. */

static CORE_ADDR
avr_convert_iaddr_to_raw (CORE_ADDR x)
{
  return ((x) & 0xffffffff);
}

/* SRAM address checks and convertions. */

static CORE_ADDR
avr_make_saddr (CORE_ADDR x)
{
  return ((x) | AVR_SMEM_START);
}

static int
avr_saddr_p (CORE_ADDR x)
{
  return (((x) & AVR_MEM_MASK) == AVR_SMEM_START);
}

static CORE_ADDR
avr_convert_saddr_to_raw (CORE_ADDR x)
{
  return ((x) & 0xffffffff);
}

/* EEPROM address checks and convertions. I don't know if these will ever
   actually be used, but I've added them just the same. TRoth */

/* TRoth/2002-04-08: Commented out for now to allow fix for problem with large
   programs in the mega128. */

/*  static CORE_ADDR */
/*  avr_make_eaddr (CORE_ADDR x) */
/*  { */
/*    return ((x) | AVR_EMEM_START); */
/*  } */

/*  static int */
/*  avr_eaddr_p (CORE_ADDR x) */
/*  { */
/*    return (((x) & AVR_MEM_MASK) == AVR_EMEM_START); */
/*  } */

/*  static CORE_ADDR */
/*  avr_convert_eaddr_to_raw (CORE_ADDR x) */
/*  { */
/*    return ((x) & 0xffffffff); */
/*  } */

/* Convert from address to pointer and vice-versa. */

static void
avr_address_to_pointer (struct type *type, void *buf, CORE_ADDR addr)
{
  /* Is it a code address?  */
  if (TYPE_CODE (TYPE_TARGET_TYPE (type)) == TYPE_CODE_FUNC
      || TYPE_CODE (TYPE_TARGET_TYPE (type)) == TYPE_CODE_METHOD)
    {
      store_unsigned_integer (buf, TYPE_LENGTH (type),
			      avr_convert_iaddr_to_raw (addr));
    }
  else
    {
      /* Strip off any upper segment bits.  */
      store_unsigned_integer (buf, TYPE_LENGTH (type),
			      avr_convert_saddr_to_raw (addr));
    }
}

static CORE_ADDR
avr_pointer_to_address (struct type *type, const void *buf)
{
  CORE_ADDR addr = extract_address (buf, TYPE_LENGTH (type));

  if (TYPE_CODE_SPACE (TYPE_TARGET_TYPE (type)))
    {
      fprintf_unfiltered (gdb_stderr, "CODE_SPACE ---->> ptr->addr: 0x%lx\n",
			  addr);
      fprintf_unfiltered (gdb_stderr,
			  "+++ If you see this, please send me an email <troth@verinet.com>\n");
    }

  /* Is it a code address?  */
  if (TYPE_CODE (TYPE_TARGET_TYPE (type)) == TYPE_CODE_FUNC
      || TYPE_CODE (TYPE_TARGET_TYPE (type)) == TYPE_CODE_METHOD
      || TYPE_CODE_SPACE (TYPE_TARGET_TYPE (type)))
    return avr_make_iaddr (addr);
  else
    return avr_make_saddr (addr);
}

static CORE_ADDR
avr_read_pc (ptid_t ptid)
{
  ptid_t save_ptid;
  CORE_ADDR pc;
  CORE_ADDR retval;

  save_ptid = inferior_ptid;
  inferior_ptid = ptid;
  pc = (int) read_register (AVR_PC_REGNUM);
  inferior_ptid = save_ptid;
  retval = avr_make_iaddr (pc);
  return retval;
}

static void
avr_write_pc (CORE_ADDR val, ptid_t ptid)
{
  ptid_t save_ptid;

  save_ptid = inferior_ptid;
  inferior_ptid = ptid;
  write_register (AVR_PC_REGNUM, avr_convert_iaddr_to_raw (val));
  inferior_ptid = save_ptid;
}

static CORE_ADDR
avr_read_sp (void)
{
  return (avr_make_saddr (read_register (AVR_SP_REGNUM)));
}

static void
avr_write_sp (CORE_ADDR val)
{
  write_register (AVR_SP_REGNUM, avr_convert_saddr_to_raw (val));
}

static CORE_ADDR
avr_read_fp (void)
{
  return (avr_make_saddr (read_register (AVR_FP_REGNUM)));
}

/* Translate a GDB virtual ADDR/LEN into a format the remote target
   understands.  Returns number of bytes that can be transfered
   starting at TARG_ADDR.  Return ZERO if no bytes can be transfered
   (segmentation fault).

   TRoth/2002-04-08: Could this be used to check for dereferencing an invalid
   pointer? */

static void
avr_remote_translate_xfer_address (CORE_ADDR memaddr, int nr_bytes,
				   CORE_ADDR *targ_addr, int *targ_len)
{
  long out_addr;
  long out_len;

  /* FIXME: TRoth: Do nothing for now. Will need to examine memaddr at this
     point and see if the high bit are set with the masks that we want. */

  *targ_addr = memaddr;
  *targ_len = nr_bytes;
}

/* Function pointers obtained from the target are half of what gdb expects so
   multiply by 2. */

static CORE_ADDR
avr_convert_from_func_ptr_addr (CORE_ADDR addr)
{
  return addr * 2;
}

/* avr_scan_prologue is also used as the frame_init_saved_regs().

   Put here the code to store, into fi->saved_regs, the addresses of
   the saved registers of frame described by FRAME_INFO.  This
   includes special registers such as pc and fp saved in special ways
   in the stack frame.  sp is even more special: the address we return
   for it IS the sp for the next frame. */

/* Function: avr_scan_prologue (helper function for avr_init_extra_frame_info)
   This function decodes a AVR function prologue to determine:
     1) the size of the stack frame
     2) which registers are saved on it
     3) the offsets of saved regs
   This information is stored in the "extra_info" field of the frame_info.

   A typical AVR function prologue might look like this:
        push rXX
        push r28
        push r29
        in r28,__SP_L__
        in r29,__SP_H__
        sbiw r28,<LOCALS_SIZE>
        in __tmp_reg__,__SREG__
        cli
        out __SP_L__,r28
        out __SREG__,__tmp_reg__
        out __SP_H__,r29

  A `-mcall-prologues' prologue look like this:
        ldi r26,<LOCALS_SIZE>
        ldi r27,<LOCALS_SIZE>/265
        ldi r30,pm_lo8(.L_foo_body)
        ldi r31,pm_hi8(.L_foo_body)
        rjmp __prologue_saves__+RRR
  .L_foo_body:  */

static void
avr_scan_prologue (struct frame_info *fi)
{
  CORE_ADDR prologue_start;
  CORE_ADDR prologue_end;
  int i;
  unsigned short insn;
  int regno;
  int scan_stage = 0;
  char *name;
  struct minimal_symbol *msymbol;
  int prologue_len;
  unsigned char prologue[AVR_MAX_PROLOGUE_SIZE];
  int vpc = 0;

  get_frame_extra_info (fi)->framereg = AVR_SP_REGNUM;

  if (find_pc_partial_function
      (get_frame_pc (fi), &name, &prologue_start, &prologue_end))
    {
      struct symtab_and_line sal = find_pc_line (prologue_start, 0);

      if (sal.line == 0)	/* no line info, use current PC */
	prologue_end = get_frame_pc (fi);
      else if (sal.end < prologue_end)	/* next line begins after fn end */
	prologue_end = sal.end;	/* (probably means no prologue)  */
    }
  else
    /* We're in the boondocks: allow for */
    /* 19 pushes, an add, and "mv fp,sp" */
    prologue_end = prologue_start + AVR_MAX_PROLOGUE_SIZE;

  prologue_end = min (prologue_end, get_frame_pc (fi));

  /* Search the prologue looking for instructions that set up the
     frame pointer, adjust the stack pointer, and save registers.  */

  get_frame_extra_info (fi)->framesize = 0;
  prologue_len = prologue_end - prologue_start;
  read_memory (prologue_start, prologue, prologue_len);

  /* Scanning main()'s prologue
     ldi r28,lo8(<RAM_ADDR> - <LOCALS_SIZE>)
     ldi r29,hi8(<RAM_ADDR> - <LOCALS_SIZE>)
     out __SP_H__,r29
     out __SP_L__,r28 */

  if (name && strcmp ("main", name) == 0 && prologue_len == 8)
    {
      CORE_ADDR locals;
      unsigned char img[] = {
	0xde, 0xbf,		/* out __SP_H__,r29 */
	0xcd, 0xbf		/* out __SP_L__,r28 */
      };

      get_frame_extra_info (fi)->framereg = AVR_FP_REGNUM;
      insn = EXTRACT_INSN (&prologue[vpc]);
      /* ldi r28,lo8(<RAM_ADDR> - <LOCALS_SIZE>) */
      if ((insn & 0xf0f0) == 0xe0c0)
	{
	  locals = (insn & 0xf) | ((insn & 0x0f00) >> 4);
	  insn = EXTRACT_INSN (&prologue[vpc + 2]);
	  /* ldi r29,hi8(<RAM_ADDR> - <LOCALS_SIZE>) */
	  if ((insn & 0xf0f0) == 0xe0d0)
	    {
	      locals |= ((insn & 0xf) | ((insn & 0x0f00) >> 4)) << 8;
	      if (memcmp (prologue + vpc + 4, img, sizeof (img)) == 0)
		{
		  deprecated_update_frame_base_hack (fi, locals);

		  get_frame_extra_info (fi)->is_main = 1;
		  return;
		}
	    }
	}
    }

  /* Scanning `-mcall-prologues' prologue
     FIXME: mega prologue have a 12 bytes long */

  while (prologue_len <= 12)	/* I'm use while to avoit many goto's */
    {
      int loc_size;
      int body_addr;
      unsigned num_pushes;

      insn = EXTRACT_INSN (&prologue[vpc]);
      /* ldi r26,<LOCALS_SIZE> */
      if ((insn & 0xf0f0) != 0xe0a0)
	break;
      loc_size = (insn & 0xf) | ((insn & 0x0f00) >> 4);

      insn = EXTRACT_INSN (&prologue[vpc + 2]);
      /* ldi r27,<LOCALS_SIZE> / 256 */
      if ((insn & 0xf0f0) != 0xe0b0)
	break;
      loc_size |= ((insn & 0xf) | ((insn & 0x0f00) >> 4)) << 8;

      insn = EXTRACT_INSN (&prologue[vpc + 4]);
      /* ldi r30,pm_lo8(.L_foo_body) */
      if ((insn & 0xf0f0) != 0xe0e0)
	break;
      body_addr = (insn & 0xf) | ((insn & 0x0f00) >> 4);

      insn = EXTRACT_INSN (&prologue[vpc + 6]);
      /* ldi r31,pm_hi8(.L_foo_body) */
      if ((insn & 0xf0f0) != 0xe0f0)
	break;
      body_addr |= ((insn & 0xf) | ((insn & 0x0f00) >> 4)) << 8;

      if (body_addr != (prologue_start + 10) / 2)
	break;

      msymbol = lookup_minimal_symbol ("__prologue_saves__", NULL, NULL);
      if (!msymbol)
	break;

      /* FIXME: prologue for mega have a JMP instead of RJMP */
      insn = EXTRACT_INSN (&prologue[vpc + 8]);
      /* rjmp __prologue_saves__+RRR */
      if ((insn & 0xf000) != 0xc000)
	break;

      /* Extract PC relative offset from RJMP */
      i = (insn & 0xfff) | (insn & 0x800 ? (-1 ^ 0xfff) : 0);
      /* Convert offset to byte addressable mode */
      i *= 2;
      /* Destination address */
      i += vpc + prologue_start + 10;
      /* Resovle offset (in words) from __prologue_saves__ symbol.
         Which is a pushes count in `-mcall-prologues' mode */
      num_pushes = AVR_MAX_PUSHES - (i - SYMBOL_VALUE_ADDRESS (msymbol)) / 2;

      if (num_pushes > AVR_MAX_PUSHES)
	num_pushes = 0;

      if (num_pushes)
	{
	  int from;
	  get_frame_saved_regs (fi)[AVR_FP_REGNUM + 1] = num_pushes;
	  if (num_pushes >= 2)
	    get_frame_saved_regs (fi)[AVR_FP_REGNUM] = num_pushes - 1;
	  i = 0;
	  for (from = AVR_LAST_PUSHED_REGNUM + 1 - (num_pushes - 2);
	       from <= AVR_LAST_PUSHED_REGNUM; ++from)
	    get_frame_saved_regs (fi)[from] = ++i;
	}
      get_frame_extra_info (fi)->locals_size = loc_size;
      get_frame_extra_info (fi)->framesize = loc_size + num_pushes;
      get_frame_extra_info (fi)->framereg = AVR_FP_REGNUM;
      return;
    }

  /* Scan interrupt or signal function */

  if (prologue_len >= 12)
    {
      unsigned char img[] = {
	0x78, 0x94,		/* sei */
	0x1f, 0x92,		/* push r1 */
	0x0f, 0x92,		/* push r0 */
	0x0f, 0xb6,		/* in r0,0x3f SREG */
	0x0f, 0x92,		/* push r0 */
	0x11, 0x24		/* clr r1 */
      };
      if (memcmp (prologue, img, sizeof (img)) == 0)
	{
	  vpc += sizeof (img);
	  get_frame_saved_regs (fi)[0] = 2;
	  get_frame_saved_regs (fi)[1] = 1;
	  get_frame_extra_info (fi)->framesize += 3;
	}
      else if (memcmp (img + 1, prologue, sizeof (img) - 1) == 0)
	{
	  vpc += sizeof (img) - 1;
	  get_frame_saved_regs (fi)[0] = 2;
	  get_frame_saved_regs (fi)[1] = 1;
	  get_frame_extra_info (fi)->framesize += 3;
	}
    }

  /* First stage of the prologue scanning.
     Scan pushes */

  for (; vpc <= prologue_len; vpc += 2)
    {
      insn = EXTRACT_INSN (&prologue[vpc]);
      if ((insn & 0xfe0f) == 0x920f)	/* push rXX */
	{
	  /* Bits 4-9 contain a mask for registers R0-R32. */
	  regno = (insn & 0x1f0) >> 4;
	  ++get_frame_extra_info (fi)->framesize;
	  get_frame_saved_regs (fi)[regno] = get_frame_extra_info (fi)->framesize;
	  scan_stage = 1;
	}
      else
	break;
    }

  /* Second stage of the prologue scanning.
     Scan:
     in r28,__SP_L__
     in r29,__SP_H__ */

  if (scan_stage == 1 && vpc + 4 <= prologue_len)
    {
      unsigned char img[] = {
	0xcd, 0xb7,		/* in r28,__SP_L__ */
	0xde, 0xb7		/* in r29,__SP_H__ */
      };
      unsigned short insn1;

      if (memcmp (prologue + vpc, img, sizeof (img)) == 0)
	{
	  vpc += 4;
	  get_frame_extra_info (fi)->framereg = AVR_FP_REGNUM;
	  scan_stage = 2;
	}
    }

  /* Third stage of the prologue scanning. (Really two stages)
     Scan for:
     sbiw r28,XX or subi r28,lo8(XX)
     sbci r29,hi8(XX)
     in __tmp_reg__,__SREG__
     cli
     out __SP_L__,r28
     out __SREG__,__tmp_reg__
     out __SP_H__,r29 */

  if (scan_stage == 2 && vpc + 12 <= prologue_len)
    {
      int locals_size = 0;
      unsigned char img[] = {
	0x0f, 0xb6,		/* in r0,0x3f */
	0xf8, 0x94,		/* cli */
	0xcd, 0xbf,		/* out 0x3d,r28 ; SPL */
	0x0f, 0xbe,		/* out 0x3f,r0  ; SREG */
	0xde, 0xbf		/* out 0x3e,r29 ; SPH */
      };
      unsigned char img_sig[] = {
	0xcd, 0xbf,		/* out 0x3d,r28 ; SPL */
	0xde, 0xbf		/* out 0x3e,r29 ; SPH */
      };
      unsigned char img_int[] = {
	0xf8, 0x94,		/* cli */
	0xcd, 0xbf,		/* out 0x3d,r28 ; SPL */
	0x78, 0x94,		/* sei */
	0xde, 0xbf		/* out 0x3e,r29 ; SPH */
      };

      insn = EXTRACT_INSN (&prologue[vpc]);
      vpc += 2;
      if ((insn & 0xff30) == 0x9720)	/* sbiw r28,XXX */
	locals_size = (insn & 0xf) | ((insn & 0xc0) >> 2);
      else if ((insn & 0xf0f0) == 0x50c0)	/* subi r28,lo8(XX) */
	{
	  locals_size = (insn & 0xf) | ((insn & 0xf00) >> 4);
	  insn = EXTRACT_INSN (&prologue[vpc]);
	  vpc += 2;
	  locals_size += ((insn & 0xf) | ((insn & 0xf00) >> 4) << 8);
	}
      else
	return;
      get_frame_extra_info (fi)->locals_size = locals_size;
      get_frame_extra_info (fi)->framesize += locals_size;
    }
}

/* This function actually figures out the frame address for a given pc and
   sp.  This is tricky  because we sometimes don't use an explicit
   frame pointer, and the previous stack pointer isn't necessarily recorded
   on the stack.  The only reliable way to get this info is to
   examine the prologue.  */

static void
avr_init_extra_frame_info (int fromleaf, struct frame_info *fi)
{
  int reg;

  if (get_next_frame (fi))
    deprecated_update_frame_pc_hack (fi, FRAME_SAVED_PC (get_next_frame (fi)));

  frame_extra_info_zalloc (fi, sizeof (struct frame_extra_info));
  frame_saved_regs_zalloc (fi);

  get_frame_extra_info (fi)->return_pc = 0;
  get_frame_extra_info (fi)->args_pointer = 0;
  get_frame_extra_info (fi)->locals_size = 0;
  get_frame_extra_info (fi)->framereg = 0;
  get_frame_extra_info (fi)->framesize = 0;
  get_frame_extra_info (fi)->is_main = 0;

  avr_scan_prologue (fi);

  if (DEPRECATED_PC_IN_CALL_DUMMY (get_frame_pc (fi), get_frame_base (fi),
				   get_frame_base (fi)))
    {
      /* We need to setup fi->frame here because run_stack_dummy gets it wrong
         by assuming it's always FP.  */
      deprecated_update_frame_base_hack (fi, deprecated_read_register_dummy (get_frame_pc (fi), get_frame_base (fi),
									     AVR_PC_REGNUM));
    }
  else if (!get_next_frame (fi))
    /* this is the innermost frame? */
    deprecated_update_frame_base_hack (fi, read_register (get_frame_extra_info (fi)->framereg));
  else if (get_frame_extra_info (fi)->is_main != 1)
    /* not the innermost frame, not `main' */
    /* If we have an next frame,  the callee saved it. */
    {
      struct frame_info *next_fi = get_next_frame (fi);
      if (get_frame_extra_info (fi)->framereg == AVR_SP_REGNUM)
	deprecated_update_frame_base_hack (fi, (get_frame_base (next_fi)
						+ 2 /* ret addr */
						+ get_frame_extra_info (next_fi)->framesize));
      /* FIXME: I don't analyse va_args functions  */
      else
	{
	  CORE_ADDR fp = 0;
	  CORE_ADDR fp1 = 0;
	  unsigned int fp_low, fp_high;

	  /* Scan all frames */
	  for (; next_fi; next_fi = get_next_frame (next_fi))
	    {
	      /* look for saved AVR_FP_REGNUM */
	      if (get_frame_saved_regs (next_fi)[AVR_FP_REGNUM] && !fp)
		fp = get_frame_saved_regs (next_fi)[AVR_FP_REGNUM];
	      /* look for saved AVR_FP_REGNUM + 1 */
	      if (get_frame_saved_regs (next_fi)[AVR_FP_REGNUM + 1] && !fp1)
		fp1 = get_frame_saved_regs (next_fi)[AVR_FP_REGNUM + 1];
	    }
	  fp_low = (fp ? read_memory_unsigned_integer (avr_make_saddr (fp), 1)
		    : read_register (AVR_FP_REGNUM)) & 0xff;
	  fp_high =
	    (fp1 ? read_memory_unsigned_integer (avr_make_saddr (fp1), 1) :
	     read_register (AVR_FP_REGNUM + 1)) & 0xff;
	  deprecated_update_frame_base_hack (fi, fp_low | (fp_high << 8));
	}
    }

  /* TRoth: Do we want to do this if we are in main? I don't think we should
     since return_pc makes no sense when we are in main. */

  if ((get_frame_pc (fi)) && (get_frame_extra_info (fi)->is_main == 0))
    /* We are not in CALL_DUMMY */
    {
      CORE_ADDR addr;
      int i;

      addr = get_frame_base (fi) + get_frame_extra_info (fi)->framesize + 1;

      /* Return address in stack in different endianness */

      get_frame_extra_info (fi)->return_pc =
	read_memory_unsigned_integer (avr_make_saddr (addr), 1) << 8;
      get_frame_extra_info (fi)->return_pc |=
	read_memory_unsigned_integer (avr_make_saddr (addr + 1), 1);

      /* This return address in words,
         must be converted to the bytes address */
      get_frame_extra_info (fi)->return_pc *= 2;

      /* Resolve a pushed registers addresses */
      for (i = 0; i < NUM_REGS; i++)
	{
	  if (get_frame_saved_regs (fi)[i])
	    get_frame_saved_regs (fi)[i] = addr - get_frame_saved_regs (fi)[i];
	}
    }
}

/* Restore the machine to the state it had before the current frame was
   created.  Usually used either by the "RETURN" command, or by
   call_function_by_hand after the dummy_frame is finished. */

static void
avr_pop_frame (void)
{
  unsigned regnum;
  CORE_ADDR saddr;
  struct frame_info *frame = get_current_frame ();

  if (DEPRECATED_PC_IN_CALL_DUMMY (get_frame_pc (frame),
				   get_frame_base (frame),
				   get_frame_base (frame)))
    {
      generic_pop_dummy_frame ();
    }
  else
    {
      /* TRoth: Why only loop over 8 registers? */

      for (regnum = 0; regnum < 8; regnum++)
	{
	  /* Don't forget AVR_SP_REGNUM in a frame_saved_regs struct is the
	     actual value we want, not the address of the value we want.  */
	  if (get_frame_saved_regs (frame)[regnum] && regnum != AVR_SP_REGNUM)
	    {
	      saddr = avr_make_saddr (get_frame_saved_regs (frame)[regnum]);
	      write_register (regnum,
			      read_memory_unsigned_integer (saddr, 1));
	    }
	  else if (get_frame_saved_regs (frame)[regnum] && regnum == AVR_SP_REGNUM)
	    write_register (regnum, get_frame_base (frame) + 2);
	}

      /* Don't forget the update the PC too!  */
      write_pc (get_frame_extra_info (frame)->return_pc);
    }
  flush_cached_frames ();
}

/* Return the saved PC from this frame. */

static CORE_ADDR
avr_frame_saved_pc (struct frame_info *frame)
{
  if (DEPRECATED_PC_IN_CALL_DUMMY (get_frame_pc (frame),
				   get_frame_base (frame),
				   get_frame_base (frame)))
    return deprecated_read_register_dummy (get_frame_pc (frame),
					   get_frame_base (frame),
					   AVR_PC_REGNUM);
  else
    return get_frame_extra_info (frame)->return_pc;
}

static CORE_ADDR
avr_saved_pc_after_call (struct frame_info *frame)
{
  unsigned char m1, m2;
  unsigned int sp = read_register (AVR_SP_REGNUM);
  m1 = read_memory_unsigned_integer (avr_make_saddr (sp + 1), 1);
  m2 = read_memory_unsigned_integer (avr_make_saddr (sp + 2), 1);
  return (m2 | (m1 << 8)) * 2;
}

/* Returns the return address for a dummy. */

static CORE_ADDR
avr_call_dummy_address (void)
{
  return entry_point_address ();
}

/* Setup the return address for a dummy frame, as called by
   call_function_by_hand.  Only necessary when you are using an empty
   CALL_DUMMY. */

static CORE_ADDR
avr_push_return_address (CORE_ADDR pc, CORE_ADDR sp)
{
  unsigned char buf[2];
  int wordsize = 2;
#if 0
  struct minimal_symbol *msymbol;
  CORE_ADDR mon_brk;
#endif

  buf[0] = 0;
  buf[1] = 0;
  sp -= wordsize;
  write_memory (sp + 1, buf, 2);

#if 0
  /* FIXME: TRoth/2002-02-18: This should probably be removed since it's a
     left-over from Denis' original patch which used avr-mon for the target
     instead of the generic remote target. */
  if ((strcmp (target_shortname, "avr-mon") == 0)
      && (msymbol = lookup_minimal_symbol ("gdb_break", NULL, NULL)))
    {
      mon_brk = SYMBOL_VALUE_ADDRESS (msymbol);
      store_unsigned_integer (buf, wordsize, mon_brk / 2);
      sp -= wordsize;
      write_memory (sp + 1, buf + 1, 1);
      write_memory (sp + 2, buf, 1);
    }
#endif
  return sp;
}

static CORE_ADDR
avr_skip_prologue (CORE_ADDR pc)
{
  CORE_ADDR func_addr, func_end;
  struct symtab_and_line sal;

  /* See what the symbol table says */

  if (find_pc_partial_function (pc, NULL, &func_addr, &func_end))
    {
      sal = find_pc_line (func_addr, 0);

      /* troth/2002-08-05: For some very simple functions, gcc doesn't
         generate a prologue and the sal.end ends up being the 2-byte ``ret''
         instruction at the end of the function, but func_end ends up being
         the address of the first instruction of the _next_ function. By
         adjusting func_end by 2 bytes, we can catch these functions and not
         return sal.end if it is the ``ret'' instruction. */

      if (sal.line != 0 && sal.end < (func_end-2))
	return sal.end;
    }

/* Either we didn't find the start of this function (nothing we can do),
   or there's no line info, or the line after the prologue is after
   the end of the function (there probably isn't a prologue). */

  return pc;
}

static CORE_ADDR
avr_frame_address (struct frame_info *fi)
{
  return avr_make_saddr (get_frame_base (fi));
}

/* Given a GDB frame, determine the address of the calling function's
   frame.  This will be used to create a new GDB frame struct, and
   then INIT_EXTRA_FRAME_INFO and DEPRECATED_INIT_FRAME_PC will be
   called for the new frame.

   For us, the frame address is its stack pointer value, so we look up
   the function prologue to determine the caller's sp value, and return it.  */

static CORE_ADDR
avr_frame_chain (struct frame_info *frame)
{
  if (DEPRECATED_PC_IN_CALL_DUMMY (get_frame_pc (frame),
				   get_frame_base (frame),
				   get_frame_base (frame)))
    {
      /* initialize the return_pc now */
      get_frame_extra_info (frame)->return_pc
	= deprecated_read_register_dummy (get_frame_pc (frame),
					  get_frame_base (frame),
					  AVR_PC_REGNUM);
      return get_frame_base (frame);
    }
  return (get_frame_extra_info (frame)->is_main ? 0
	  : get_frame_base (frame) + get_frame_extra_info (frame)->framesize + 2 /* ret addr */ );
}

/* Store the address of the place in which to copy the structure the
   subroutine will return.  This is called from call_function. 

   We store structs through a pointer passed in the first Argument
   register. */

static void
avr_store_struct_return (CORE_ADDR addr, CORE_ADDR sp)
{
  write_register (0, addr);
}

/* Setup the function arguments for calling a function in the inferior.

   On the AVR architecture, there are 18 registers (R25 to R8) which are
   dedicated for passing function arguments.  Up to the first 18 arguments
   (depending on size) may go into these registers.  The rest go on the stack.

   Arguments that are larger than WORDSIZE bytes will be split between two or
   more registers as available, but will NOT be split between a register and
   the stack.

   An exceptional case exists for struct arguments (and possibly other
   aggregates such as arrays) -- if the size is larger than WORDSIZE bytes but
   not a multiple of WORDSIZE bytes.  In this case the argument is never split
   between the registers and the stack, but instead is copied in its entirety
   onto the stack, AND also copied into as many registers as there is room
   for.  In other words, space in registers permitting, two copies of the same
   argument are passed in.  As far as I can tell, only the one on the stack is
   used, although that may be a function of the level of compiler
   optimization.  I suspect this is a compiler bug.  Arguments of these odd
   sizes are left-justified within the word (as opposed to arguments smaller
   than WORDSIZE bytes, which are right-justified).
 
   If the function is to return an aggregate type such as a struct, the caller
   must allocate space into which the callee will copy the return value.  In
   this case, a pointer to the return value location is passed into the callee
   in register R0, which displaces one of the other arguments passed in via
   registers R0 to R2. */

static CORE_ADDR
avr_push_arguments (int nargs, struct value **args, CORE_ADDR sp,
		    int struct_return, CORE_ADDR struct_addr)
{
  int stack_alloc, stack_offset;
  int wordsize;
  int argreg;
  int argnum;
  struct type *type;
  CORE_ADDR regval;
  char *val;
  char valbuf[4];
  int len;

  wordsize = 1;
#if 0
  /* Now make sure there's space on the stack */
  for (argnum = 0, stack_alloc = 0; argnum < nargs; argnum++)
    stack_alloc += TYPE_LENGTH (VALUE_TYPE (args[argnum]));
  sp -= stack_alloc;		/* make room on stack for args */
  /* we may over-allocate a little here, but that won't hurt anything */
#endif
  argreg = 25;
  if (struct_return)		/* "struct return" pointer takes up one argreg */
    {
      write_register (--argreg, struct_addr);
    }

  /* Now load as many as possible of the first arguments into registers, and
     push the rest onto the stack.  There are 3N bytes in three registers
     available.  Loop thru args from first to last.  */

  for (argnum = 0, stack_offset = 0; argnum < nargs; argnum++)
    {
      type = VALUE_TYPE (args[argnum]);
      len = TYPE_LENGTH (type);
      val = (char *) VALUE_CONTENTS (args[argnum]);

      /* NOTE WELL!!!!!  This is not an "else if" clause!!!  That's because
         some *&^%$ things get passed on the stack AND in the registers!  */
      while (len > 0)
	{			/* there's room in registers */
	  len -= wordsize;
	  regval = extract_address (val + len, wordsize);
	  write_register (argreg--, regval);
	}
    }
  return sp;
}

/* Initialize the gdbarch structure for the AVR's. */

static struct gdbarch *
avr_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
{
  /* FIXME: TRoth/2002-02-18: I have no idea if avr_call_dummy_words[] should
     be bigger or not. Initial testing seems to show that `call my_func()`
     works and backtrace from a breakpoint within the call looks correct.
     Admittedly, I haven't tested with more than a very simple program. */
  static LONGEST avr_call_dummy_words[] = { 0 };

  struct gdbarch *gdbarch;
  struct gdbarch_tdep *tdep;

  /* Find a candidate among the list of pre-declared architectures. */
  arches = gdbarch_list_lookup_by_info (arches, &info);
  if (arches != NULL)
    return arches->gdbarch;

  /* None found, create a new architecture from the information provided. */
  tdep = XMALLOC (struct gdbarch_tdep);
  gdbarch = gdbarch_alloc (&info, tdep);

  /* NOTE: cagney/2002-12-06: This can be deleted when this arch is
     ready to unwind the PC first (see frame.c:get_prev_frame()).  */
  set_gdbarch_deprecated_init_frame_pc (gdbarch, init_frame_pc_default);

  /* If we ever need to differentiate the device types, do it here. */
  switch (info.bfd_arch_info->mach)
    {
    case bfd_mach_avr1:
    case bfd_mach_avr2:
    case bfd_mach_avr3:
    case bfd_mach_avr4:
    case bfd_mach_avr5:
      break;
    }

  set_gdbarch_short_bit (gdbarch, 2 * TARGET_CHAR_BIT);
  set_gdbarch_int_bit (gdbarch, 2 * TARGET_CHAR_BIT);
  set_gdbarch_long_bit (gdbarch, 4 * TARGET_CHAR_BIT);
  set_gdbarch_long_long_bit (gdbarch, 8 * TARGET_CHAR_BIT);
  set_gdbarch_ptr_bit (gdbarch, 2 * TARGET_CHAR_BIT);
  set_gdbarch_addr_bit (gdbarch, 32);
  set_gdbarch_bfd_vma_bit (gdbarch, 32);	/* FIXME: TRoth/2002-02-18: Is this needed? */

  set_gdbarch_float_bit (gdbarch, 4 * TARGET_CHAR_BIT);
  set_gdbarch_double_bit (gdbarch, 4 * TARGET_CHAR_BIT);
  set_gdbarch_long_double_bit (gdbarch, 4 * TARGET_CHAR_BIT);

  set_gdbarch_float_format (gdbarch, &floatformat_ieee_single_little);
  set_gdbarch_double_format (gdbarch, &floatformat_ieee_single_little);
  set_gdbarch_long_double_format (gdbarch, &floatformat_ieee_single_little);

  set_gdbarch_read_pc (gdbarch, avr_read_pc);
  set_gdbarch_write_pc (gdbarch, avr_write_pc);
  set_gdbarch_read_fp (gdbarch, avr_read_fp);
  set_gdbarch_read_sp (gdbarch, avr_read_sp);
  set_gdbarch_write_sp (gdbarch, avr_write_sp);

  set_gdbarch_num_regs (gdbarch, AVR_NUM_REGS);

  set_gdbarch_sp_regnum (gdbarch, AVR_SP_REGNUM);
  set_gdbarch_fp_regnum (gdbarch, AVR_FP_REGNUM);
  set_gdbarch_pc_regnum (gdbarch, AVR_PC_REGNUM);

  set_gdbarch_register_name (gdbarch, avr_register_name);
  set_gdbarch_register_size (gdbarch, 1);
  set_gdbarch_register_bytes (gdbarch, AVR_NUM_REG_BYTES);
  set_gdbarch_register_byte (gdbarch, avr_register_byte);
  set_gdbarch_register_raw_size (gdbarch, avr_register_raw_size);
  set_gdbarch_max_register_raw_size (gdbarch, 4);
  set_gdbarch_register_virtual_size (gdbarch, avr_register_virtual_size);
  set_gdbarch_max_register_virtual_size (gdbarch, 4);
  set_gdbarch_register_virtual_type (gdbarch, avr_register_virtual_type);

  set_gdbarch_print_insn (gdbarch, print_insn_avr);

  set_gdbarch_call_dummy_address (gdbarch, avr_call_dummy_address);
  set_gdbarch_call_dummy_start_offset (gdbarch, 0);
  set_gdbarch_call_dummy_breakpoint_offset_p (gdbarch, 1);
  set_gdbarch_call_dummy_breakpoint_offset (gdbarch, 0);
  set_gdbarch_call_dummy_length (gdbarch, 0);
  set_gdbarch_call_dummy_p (gdbarch, 1);
  set_gdbarch_call_dummy_words (gdbarch, avr_call_dummy_words);
  set_gdbarch_call_dummy_stack_adjust_p (gdbarch, 0);
  set_gdbarch_fix_call_dummy (gdbarch, generic_fix_call_dummy);

/*    set_gdbarch_believe_pcc_promotion (gdbarch, 1); // TRoth: should this be set? */

  set_gdbarch_address_to_pointer (gdbarch, avr_address_to_pointer);
  set_gdbarch_pointer_to_address (gdbarch, avr_pointer_to_address);
  set_gdbarch_push_arguments (gdbarch, avr_push_arguments);
  set_gdbarch_push_return_address (gdbarch, avr_push_return_address);
  set_gdbarch_pop_frame (gdbarch, avr_pop_frame);

  set_gdbarch_use_struct_convention (gdbarch, generic_use_struct_convention);
  set_gdbarch_store_struct_return (gdbarch, avr_store_struct_return);

  set_gdbarch_frame_init_saved_regs (gdbarch, avr_scan_prologue);
  set_gdbarch_init_extra_frame_info (gdbarch, avr_init_extra_frame_info);
  set_gdbarch_skip_prologue (gdbarch, avr_skip_prologue);
  set_gdbarch_inner_than (gdbarch, core_addr_lessthan);

  set_gdbarch_decr_pc_after_break (gdbarch, 0);

  set_gdbarch_function_start_offset (gdbarch, 0);
  set_gdbarch_remote_translate_xfer_address (gdbarch,
					     avr_remote_translate_xfer_address);
  set_gdbarch_frame_args_skip (gdbarch, 0);
  set_gdbarch_frameless_function_invocation (gdbarch, frameless_look_for_prologue);	/* ??? */
  set_gdbarch_frame_chain (gdbarch, avr_frame_chain);
  set_gdbarch_frame_saved_pc (gdbarch, avr_frame_saved_pc);
  set_gdbarch_frame_args_address (gdbarch, avr_frame_address);
  set_gdbarch_frame_locals_address (gdbarch, avr_frame_address);
  set_gdbarch_saved_pc_after_call (gdbarch, avr_saved_pc_after_call);
  set_gdbarch_frame_num_args (gdbarch, frame_num_args_unknown);

  set_gdbarch_convert_from_func_ptr_addr (gdbarch,
					  avr_convert_from_func_ptr_addr);

  return gdbarch;
}

/* Send a query request to the avr remote target asking for values of the io
   registers. If args parameter is not NULL, then the user has requested info
   on a specific io register [This still needs implemented and is ignored for
   now]. The query string should be one of these forms:

   "Ravr.io_reg" -> reply is "NN" number of io registers

   "Ravr.io_reg:addr,len" where addr is first register and len is number of
   registers to be read. The reply should be "<NAME>,VV;" for each io register
   where, <NAME> is a string, and VV is the hex value of the register.

   All io registers are 8-bit. */

static void
avr_io_reg_read_command (char *args, int from_tty)
{
  int bufsiz = 0;
  char buf[400];
  char query[400];
  char *p;
  unsigned int nreg = 0;
  unsigned int val;
  int i, j, k, step;

/*    fprintf_unfiltered (gdb_stderr, "DEBUG: avr_io_reg_read_command (\"%s\", %d)\n", */
/*             args, from_tty); */

  if (!current_target.to_query)
    {
      fprintf_unfiltered (gdb_stderr,
			  "ERR: info io_registers NOT supported by current target\n");
      return;
    }

  /* Just get the maximum buffer size. */
  target_query ((int) 'R', 0, 0, &bufsiz);
  if (bufsiz > sizeof (buf))
    bufsiz = sizeof (buf);

  /* Find out how many io registers the target has. */
  strcpy (query, "avr.io_reg");
  target_query ((int) 'R', query, buf, &bufsiz);

  if (strncmp (buf, "", bufsiz) == 0)
    {
      fprintf_unfiltered (gdb_stderr,
			  "info io_registers NOT supported by target\n");
      return;
    }

  if (sscanf (buf, "%x", &nreg) != 1)
    {
      fprintf_unfiltered (gdb_stderr,
			  "Error fetching number of io registers\n");
      return;
    }

  reinitialize_more_filter ();

  printf_unfiltered ("Target has %u io registers:\n\n", nreg);

  /* only fetch up to 8 registers at a time to keep the buffer small */
  step = 8;

  for (i = 0; i < nreg; i += step)
    {
      j = step - (nreg % step);	/* how many registers this round? */

      snprintf (query, sizeof (query) - 1, "avr.io_reg:%x,%x", i, j);
      target_query ((int) 'R', query, buf, &bufsiz);

      p = buf;
      for (k = i; k < (i + j); k++)
	{
	  if (sscanf (p, "%[^,],%x;", query, &val) == 2)
	    {
	      printf_filtered ("[%02x] %-15s : %02x\n", k, query, val);
	      while ((*p != ';') && (*p != '\0'))
		p++;
	      p++;		/* skip over ';' */
	      if (*p == '\0')
		break;
	    }
	}
    }
}

void
_initialize_avr_tdep (void)
{
  register_gdbarch_init (bfd_arch_avr, avr_gdbarch_init);

  /* Add a new command to allow the user to query the avr remote target for
     the values of the io space registers in a saner way than just using
     `x/NNNb ADDR`. */

  /* FIXME: TRoth/2002-02-18: This should probably be changed to 'info avr
     io_registers' to signify it is not available on other platforms. */

  add_cmd ("io_registers", class_info, avr_io_reg_read_command,
	   "query remote avr target for io space register values", &infolist);
}